池田 純一郎

Recently, we encountered a biopsy of epithelioid rabdomyosarcoma with lymph node metastasis. A computed tomography (CT) scan showed number of swollen lymph nodes in the left neck and a huge abdominal mass occupying the right kidney. In the lymph node biopsy, tumor cells showed diffuse sheet-like growth reminiscent of carcinoma and melanoma cells with extensive distribution of coagulation necrosis. Tumor cells had abundant amphophilic cytoplasm and clear large nuclei. Most tumor cells showed severe cytologic atypia manifested in prominent nucleoli and pleomorphic nuclei. Tumor cells were focally positive for desmin. Most tumor cells showed expressons for vimentin, BAF47 (INI-1), and myogenin. On reverse transcriptase polymerase chain reaction (RT-PCR) analysis, tumor cells lacked Myo D1 and PAX3/7-FKHR transcripts and showed myogenin transcripts. On cytogenetic (karyotypic) analysis, tumor cells showed highly complex karyotypes. The patient received various regimens of chemotherapy, but 6 months after the biopsy she died with progression of the tumor. Since consent was not obtained, an autopsy was not performed.

The activity of the mechanistic target of rapamycin (mTOR) is elevated in various types of human cancers, implicating a role in tumor progression. However, the molecular mechanisms underlying mTOR upregulation remain unclear. In this study, we found that the expression of mLST8, a required subunit of both mTOR complex 1 (mTORC1) and complex 2 (mTORC2), was upregulated in several human colon and prostate cancer cell lines and tissues. Knockdown of mLST8 significantly suppressed mTORC1 and mTORC2 complex formation, and it also inhibited tumor growth and invasiveness in human colon carcinoma (HCT116) and prostate cancer (LNCaP) cells. Overexpression of mLST8 induced anchor-age-independent cell growth in normal epithelial cells (HaCaT), although mLST8 knockdown had no effect on normal cell growth. mLST8 knockdown reduced mTORC2-mediated phosphorylation of AKT in both cancer and normal cells, whereas it potently inhibited mTORC1-mediated phosphorylation of 4E-BP1 specifically in cancer cells. These results suggest that mLST8 plays distinct roles in normal and cancer cells, depending upon its expression level, and that mLST8 upregulation may contribute to tumor progression by constitutively activating both the mTORC1 and mTORC2 pathways.

Cancer-initiating cells (CICs) are a limited number of cells that are essential for maintenance, recurrence, and metastasis of tumors. Aldehyde dehydrogenase 1 (ALDH1) has been recognized as a marker of CICs. We previously reported that ALDH1-high cases of uterine endometrioid adenocarcinoma showed poor prognosis, and that ALDH1 high population was more tumorigenic, invasive, and resistant to apoptosis than ALDH1 low population. Histamine plays a critical role in cancer cell proliferation, migration, and invasion. Here, we examined the effect of histamine on ALDH1 expression in endometrioid adenocarcinoma cell line. The addition of histamine increased ALDH1 high population, which was consistent with the result that histamine enhanced the invasive ability and the resistance to anticancer drug. Among 4 types of histamine receptors, histamine H1 and H2 receptor (H1R and H2R) were expressed in endometrioid adenocarcinoma cell line. The addition of H1R agonist but not H2R agonist increased ALDH1. The antagonist H1R but not H2R inhibited the effect of histamine on ALDH1 expression. These results indicated that histamine increased the expression of ALDH1 via H1R but not H2R. These findings may provide the evidence for exploring a new strategy to suppress CICs by inhibiting ALDH1 expression with histamine.

Medical applications of nonequilibrium atmospheric pressure plasma (NEAPP) have been reported in cancer therapy. Cells with tumorigenic potential are limited to a small population, called cancer-initiating cells (CICs), which are usually expressing aldehyde dehydrogenase (ALDH) in a high level. CICs are believed to cause recurrence or metastasis due to their resistance to apoptosis. Here, we examined the effect of NEAPP on CICs using human uterine endometrioid adenocarcinoma cells and poorly differentiated human gastric carcinoma cells. When treated with NEAPP, ALDH-high cells fell into apoptosis in a comparable level to ALDH-low cells. These results suggested that NEAPP treatment was effective not only on non-CICs but also on CICs. NEAPP might become a new therapeutic approach to CICs.

Cancer cells with tumorigenic potential are limited to a small population known as cancer-initiating cells (CICs). To date, CICs have not been identified in non-Hodgkin's lymphomas. Here, we investigated a candidate of CICs of an indolent non-Hodgkin's lymphoma, Waldenstrom macroglobulinemia (WM), using WM cell line MWCL-1. WM tumor expresses both B-cell and plasma cell markers, CD20 and CD138. When stained with anti-CD20 and anti-CD138 antibodies, MWCL-1 cells were classified into three subpopulations: CD20(-) CD138(-), CD20(+) CD138(-), and CD20(+) CD138(-). When cultured, CD20(-) CD138(-) cells yielded all three subpopulations, but CD20(+) cells did not yield CD20(-) CD138(-) cells. Higher reactive oxygen species (ROS) expelling and in vitro colony formation activities were detected in CD20(-) CD138(-) cells than in CD20(+) CD138(-) and CD20(+) CD138(+) cells. When cultured in the absence of serum or with anti-cancer drug, CD20(-) CD138(-) cells were resistant to apoptosis. In contrast, CD20(+) CD138(+) cells were vulnerable to apoptosis in the same condition. In fact, the immunohistochemical analysis with clinical samples revealed that tumor cells in apoptosis were CD138-positive. The production of all three subpopulations, the efficient ROS expelling and in vitro colony-forming activities, and the resistance to apoptosis suggested that the CD20(-) CD138(-) cell might be a candidate of CICs in WM.

Cancers consist of heterogeneous populations. Recently, it has been demonstrated that cells with tumorigenic potential are limited to a small population, called cancer-initiating cells (CICs). Aldehyde dehydrogenase 1 (ALDH1) is one of the markers of CICs. We previously reported that ALDH1-high cases of uterine endometrioid adenocarcinoma showed poor prognosis, and ALDH1-high population of endometrioid adenocarcinoma cell line was more tumorigenic, resistant to anti-cancer drugs, and invasive than ALDH1-low population. Here, the regulatory signaling for ALDH1 was examined. The inhibition of TGF-beta signaling increased ALDH1-high population. Among TGF-beta family members, Nodal expression and ALDH1 expression levels were mutually exclusive. Immunohistochemical analysis on clinical samples revealed Nodal-high tumor cells to be ALDH-low and vise versa, suggesting that Nodal may inhibit ALDH1 expression via stimulating TGF-beta signaling in uterine endometrioid adenocarcinoma. In fact, the addition of Nodal to endometrioid adenocarcinoma cell line reduced ALDH1-high population. Although ALDH1 mRNA level was not affected, the amount of ALDH1 protein appeared to be reduce by Nodal through ubiquitine-proteasome pathway. The regulation of TGF-beta signaling might be a novel therapeutic target of CICs in endometrioid adenocarcinoma. (C) 2013 Elsevier Inc. All rights reserved.

mTOR complex 2 (mTORC2) signaling is upregulated in multiple types of human cancer, but the molecular mechanisms underlying its activation and regulation remain elusive. Here, we show that microRNA-mediated upregulation of Rictor, an mTORC2-specific component, contributes to tumor progression. Rictor is upregulated via the repression of the miR-424/503 cluster in human prostate and colon cancer cell lines that harbor c-Src upregulation and in Src-transformed cells. The tumorigenicity and invasive activity of these cells were suppressed by re-expression of miR-424/503. Rictor upregulation promotes formation of mTORC2 and induces activation of mTORC2, resulting in promotion of tumor growth and invasion. Furthermore, downregulation of miR-424/503 is associated with Rictor upregulation in colon cancer tissues. These findings suggest that the miR-424/503-Rictor pathway plays a crucial role in tumor progression.

Cancer-initiating cells (CICs) are a limited number of cells with tumorigenic activity. Few studies have been performed on CICs in malignant lymphoma. We recently demonstrated that a small number of FoxO3a-expressing cells possessed CIC-like potential in Hodgkin's lymphoma (HL) cell lines. In the present study, FoxO3a expression was examined immunohistochemically in 137 patients with malignant lymphoma. Among patients with HL, FoxO3a-positive tumor cells were detected in 11 of 11 with nodular sclerosis classical HL, 8 of 15 with mixed cellularity classical HL, 0 of 1 with lymphocyte-rich classical HL, and 2 of 3 with nodular lymphocyte-predominant HL Only limited numbers of patients with non-HL expressed FoxO3a: 4 of 66 with diffuse large B-cell lymphoma, 1 of 20 with follicular lymphoma, and 1 of 5 with peripheral T-cell lymphoma, not otherwise specified. No FoxO3a expression was detected in patients with mantle cell lymphoma (n=3), extranodal marginal zone B-cell lymphoma (n=3), mediastinal large B-cell lymphoma (n=1), NK/T cell lymphoma (n=5), anaplastic large cell lymphoma (n=2), or T-lymphoblastic lymphoma/leukemia (n=2). These results suggest that FoxO3a is expressed mostly in patients with HL, but not in patients with non-HL Fox03a expression was limited to a small number of Hodgkin cells in a quiescent state. FoxO3a may be a CIC marker of HL, but not of non-HL (C) 2013 Elsevier GmbH. All rights reserved.

Due to accelerated energy consumption, enhanced function of mitochondria in tumour cells compared to normal cells is prerequisite for tumour development. Leucine-rich pentatricopeptide repeat motif-containing protein (LRPPRC) regulates the expression of all mitochondrial DNA-encoded mRNAs, thus plays an important role in the mitochondrial function. LRPPRC is abundantly expressed in the side population of lung adenocarcinoma cell lines, where cancer stem cells are enriched. However, the role of LRPPRC in tumour development remained to be clarified in detail. Here, the expression of LRPPRC was examined in various types of tumours, such as lung adenocarcinoma, oesophageal squamous cell carcinoma, stomach, colon, mammary and endometrial adenocarcinoma, and lymphoma. Immunohistochemistry revealed that all kinds of examined tumours abundantly expressed LRPPRC. In contrast, surrounding non-neoplastic cells hardly expressed LRPPRC. The knocked-down expression of LRPPRC in lung adenocarcinoma cells did not affect amount of side population and activity of aldehyde dehydrogenase 1, known to be highly expressed in cancer stem cells of the lung. However, the knocked-down expression of LRPPRC reduced the abilities for anti-apoptosis, invasion and in vitro colony formation in lung adenocarcinoma, as well as Hodgkin lymphoma cells. Double staining of LRPPRC with active caspase-3 in clinical samples of lung adenocarcinoma revealed that apoptotic cells were hardly observed in LRPPRC-expressing tumours. These findings indicate that LRPPRC played an important role in tumourigenesis through the resistance to apoptosis and high invasive activity. (C) 2012 Elsevier Ltd. All rights reserved.

Tumor cells with tumorigenic potential might be limited to a small population of cells, called cancer-initiating cells (CICs). CICs efficiently form colonies in vitro, yield both CIC and non-CIC populations, maintain reactive oxygen species (ROS) at low levels, show high aldehyde dehydrogenase (ALDH) activity, and are mostly in a quiescent state of the cell cycle. CICs of Hodgkin lymphoma (HL) are small in size, with low levels of ROS. The relationship between ROS level and ALDH activity in CICs was examined in HL cell lines. ROS-low and ALDH-high populations formed colonies in semi-solid cultures more efficiently than ROS-high and ALDH-low populations. ALDH-high populations yielded both ALDH-low and -high populations, whereas ALDH-low populations rarely yielded an ALDH-high population. The number of cells in a quiescent state was significantly greater in ROS-low than in ROS-high cells, whereas that of ALDH-high and ALDH-low cells was comparable to each other. These findings show that ALDH-high and ROS-low cells share CIC-like potential, but they differ in their cell cycle status, suggesting that CICs are comprised of cells with heterogeneous characteristics. Laboratory Investigation (2012) 92, 606-614; doi:10.1038/labinvest.2012.4; published online 20 February 2012

The tyrosine kinase c-Src is upregulated in various human cancers; however, the molecular mechanisms underlying c-Src-mediated tumor progression remain unclear. Here we show that downregulation of microRNA (miR)-542-3p is tightly associated with tumor progression via c-Src-related oncogenic pathways. In c-Src-transformed fibroblasts and human cancer cells that overexpress c-Src, miR-542-3p is substantially downregulated, and the ectopic expression of miR-542-3p suppresses tumor growth. We identified the integrin-linked kinase (ILK) as a conserved target of miR-542-3p. ILK upregulation promotes cell adhesion and invasion by activating the integrin-focal adhesion kinase (FAK)/c-Src pathway, and can also contribute to tumor growth via the AKT and glycogen synthase kinase 3 beta pathways. MiR-542-3p expression is downregulated by the activation of c-Src-related signaling molecules, including epidermal growth factor receptor, K-Ras and Ras/Raf/mitogen-activated protein kinase/extracellular signal-regulated kinase. In human colon cancer tissues, downregulation of miR-542-3p is significantly correlated with the upregulation of c-Src and ILK. Our results suggest that the novel c-Src-miR-542-3p-ILK-FAK circuit plays a crucial role in controlling tumor progression. Oncogene (2012) 31, 1623-1635; doi:10.1038/onc.2011.367; published online 22 August 2011

Elongator protein 3 (ELP3), the catalytic subunit of the elongator complex of RNA polymerase II, is involved in various functions, including transcriptional elongation, chromatin modification and cytoskeletal regulation. In this study, ELP3 expression was immunohistochemically examined in normal uterus tissue and uterine endometrioid adenocarcinoma tissue. ELP3 was abundantly expressed in both the proliferative and secretory phases of the endometrial cycle. However, ELP3 expression levels varied among cases of endometrioid adenocarcinoma. In patients with endometrioid adenocarcinoma, a low ELP3 expression was correlated to a high T-factor (p=0.036), tumor stage (p=0.001), lymph node metastasis (p<0.001), resistance to chemotherapy (p=0.045), recurrence (p=0.004) and poor prognosis (p=0.003). Univariate and multivariate analyses revealed that a low ELP3 expression was an independent factor for poor prognosis. In conclusion, this is the first study to examine the clinical implications of ELP3 expression in cancer.

To evaluate roles of tumor-associated macrophages (TAMs) for prognosis of classical Hodgkin lymphoma (CHL). Expression of markers for TAMs, CD68, HLA-DR, CD163, HLA-DR/CD68 (M1), and CD163/CD68 (M2) was immunohistochemically examined in 82 cases with CHL. Positively stained cells were counted and correlation of number of TAMs and patients' survival time was analyzed. Number of CD163+ cells and M2 cells was significantly correlated with shorter overall survival (P < 0.05), while it was marginally significant for CD68+ cells (P = 0.0827). HLA-DR + cells and M1 cells showed no significant correlation with overall survival. When confined to mixed cellularity subtype, number of M1 cells was correlated with favorable prognosis (P < 0.05), while M2 did not (P = 0.7). Older age and male sex were unfavorable factors for prognosis. At multivariate analysis, number of CD163+ cells, M2+ cells, and age were independent factors for poor overall survival (P = 0.03, 0.02, and 0.01, respectively). CD163+ cells and M2 cells might work to be tumor promotive in CHL. M1 cells might be tumor suppressive in mixed cellularity type.

High activity of aldehyde dehydrogenase (ALDH) is characteristic of normal and cancerous stem cells. Recently, high ALDH expression was shown to be associated with poor prognosis in uterine endometrial adenocarcinoma. The population with high ALDH activity (ALDH-hi) was more invasive, anti-apoptotic, and tumorigenic than that with low activity (ALDH-lo). Here, the transcriptional regulation of ALDH1A1 gene, which is responsible for ALDH activity, was examined in endometrial adenocarcinoma. The promoter region of ALDH1A1 contained CCAAT and octamer binding motifs, and their mutation diminished promoter activity. Among CCAAT-recognizing transcription factors, nuclear factor YA (NFYA) was involved in ALDH1A1 transcription. Two alternatively spliced isoforms of NFYA (NFYA-long and NFYA-short) have been reported. The sorted ALDH-hi population of endometrial adenocarcinoma preferentially expressed NFYA-short, whereas ALDH-lo dominantly expressed NFYA-long. NFYA-short possessed higher transactivation ability than did NFYA-long. In addition, an additive effect of NFYA with Oct-1, which recognizes octamer binding motif, was observed in ALDH1A1 transactivation. These results indicate that the alternatively spliced isoforms of NFYA, in cooperation with Oct-1, play an important role in ALDH1A1 expression in endometrial adenocarcinoma.

The tyrosine kinase c-Src is upregulated in various human cancers, but the molecular mechanisms underlying c-Src-mediated tumor growth remain unclear. Here we examined the involvement of microRNAs in the c-Src-mediated tumor growth. Microarray profiling revealed that c-Src activation downregulates a limited set of microRNAs, including miR-99a, which targets oncogenic mammalian target of rapamycin (mTOR) and fibroblast growth factor receptor 3 (FGFR3). Re-expression of miR-99a suppressed tumor growth of c-Src-transformed cells, and this effect was restored by the overexpression of mTOR. The downregulation of miR-99a was also observed in epidermal growth factor-and Ras-transformed cells, and it was suppressed by inhibiting the mitogen-activated protein kinase (MAPK) pathway. Furthermore, miR-99a downregulation is associated with mTOR/FGFR3 upregulation in various human lung cancer cells/tissues. The tumorigenicity of these cells was suppressed by the introduction of miR-99a. These findings suggest that the miR-99a-mTOR/FGFR3 pathway is crucial for controlling tumor growth in a wide range of human cancers that harbor upregulation of the Src-related oncogenic pathways. Oncogene (2011) 30, 3489-3501; doi:10.1038/onc.2011.63; published online 7 March 2011

Aldehyde dehydrogenase (ALDH) 1 is expressed in various stem/progenitor cells, including cancer-initiating cells (CICs). In the present study, ALDH1 expression was immunohistochemically examined in diffuse large B-cell lymphoma (DLBCL). Unexpectedly, ALDH I expression was occasionally detected in stromal cells, but not in lymphoma cells. Positively stained cells were CD68(+) cells with voluminous cytoplasm and fascin(+) cells with reticular morphology, designated as macrophages and dendritic cells (DCs), respectively. The presence of ALDH1(+) macrophages was not correlated with stage, response to therapies and prognosis. However, cases with ALDH1(+) DCs were mostly nodal, which showed a poorer response to therapies and a worse overall survival rate than cases without ALDH1(+) DCs. The presence of ALDH1(+) DCs appears to be involved in the malignant potential of DLBCL in lymph node.

Objectives: The presence of B-cell clones in 76 cases with peripheral T-cell lymphoma (PTCL) and precursor T-lymphoblastic lymphoma (T-LBL) and its correlation with Epstein-Barr virus (EBV) was studied. Methods: DNA was extracted from paraffin sections and/or fresh-frozen samples and then used for clonality analysis using a modified BIOMED-2 polymerase chain reaction (PCR)-based method. Results: T- and B-cell clones were detected in 59 (77.6%) and 14 (18.4%) of 76 patients, respectively: 90% and 30% of cases with PTCL, not otherwise specified, 76.4% and 17.6% of cases with angioimmunoblastic T-cell lymphoma, 77% and 7.6% of cases with adult T-cell lymphoma, 50% and 0% of cases with anaplastic large T-cell lymphoma, 62.5% and 12.5% of cases with T-LBL, and 50% and 0% of cases with intestinal T-cell lymphoma, respectively. Histological and immunohistochemical analyses revealed the presence of large B cells in lesional tissues, which were occasionally monoclonal. The presence of B-cell clones was highly associated with EBV positivity, as revealed by in situ hybridization. In two cases that were evaluated by serial histological and molecular examination, EBV-positive cells persisted in one and disappeared in the other. Conclusions: These findings suggest a role for EBV in the evolution of B-cell clones in T-cell lymphomas.

Aldehyde dehydrogenase 1 (ALDH1) is expressed in stem/progenitor cells, including cancer-initiating cells (CIC) of various organs. In the present study, ALDH1 expression was immunohistochemically examined in uterine endometrioid adenocarcinoma. The ALDH1 was expressed in a small portion of tumor cells, and these ALDH1-expressing cells were less mature than ALDH1-non-expressing cells. The ALDH1-expressing (ALDH1-hi) cells were more tumorigenic, resistant to anti-cancer agents and more invasive than ALDH1-lo cells. Culture of the sorted ALDH1-hi cells yielded both ALDH1-hi and ALDH1-lo cells, whereas ALDH1-lo cells yielded ALDH-lo cells alone. Clinically, a high-level of ALDH1 expression in tumor cells was correlated with T category, lymphatic invasion, recurrence and prognosis of patients. Patients with high ALDH1 expression showed poorer prognoses than those with low expression (P = 0.015 for disease-free survival [DFS] and P = 0.010 for overall survival [OS]), and high ALDH1 expression was an independent factor for poor prognosis. Aldehyde dehydrogenase 1 is a candidate for CIC marker for uterine endometrioid adenocarcinoma. (Cancer Sci 2011; 102: 903-908)

According to previous reports, the frequency of Epstein Barr virus (EBV) positivity in diffuse large B-cell lymphoma is higher in East Asia (approximately 9%) than in Western countries. The presence of the EBV genome was examined in diffuse large B-cell lymphoma patients registered with the Osaka Lymphoma Study Group (OLSG) in Osaka, Japan, situated in East Asia. The EBV-positive rate was examined with in situ hybridization (ISH) in 484 immunocompetent diffuse large B-cell lymphoma patients registered with OLSG. The male-to-female ratio was 1.29, with ages ranging from 16 to 95 (median, 68) years. ISH with EBV-encoded small RNAs (EBER) probes revealed positive signals in the nuclei of tumor cells: the frequency of positively stained cells among all tumor cells was almost none in 458 cases, 5-10% in 5, 10-20% in 5, 20-50% in 11, and >50% in 5. When the frequency was >20% or >50%, the EBV-positive rate in the present series (3.3% or 1.0%) was rather similar to that reported in Western cases. Careful evaluation of patient backgrounds, including age distribution, type of lymphomas, exclusion of immunocompromised patients, and establishment of definite criteria for EBV positivity (>20%, >50%, or almost all tumor cells) are essential in comparing geographical differences. J. Med. Vim,. 83:317-321, 2011. (C) 2010 Wiley-Liss, Inc.

Tumor cells with tumorigenic potential are limited to a small cell population known as cancer stem cells (CSCs) CSCs yield both CSCs and non CSCs whereas non CSCs do not yield CSCs CSCs have not been identified m any malignant lymphomas Hodgkin lymphoma (HL) is a mostly B cell neoplasm that can be diagnosed by the presence of multinucleated (Reed Sternberg RS) cells admixed with Hodgkin cells with distinct nucleoli and various inflammatory cells Here the tumorigenic potential of cells with a single nucleus (S) and cells with multiple nuclei (M) which may be equivalent to Hodgkin and RS cells respectively was examined in HL cell lines L1236 and L428 Cultures of single S cells yielded both S and M cells whereas M cell cultures yielded only M cells When either cultured in methylcellulose or inoculated into NOD/SCID mice the colony number and tumor size were both larger in S than in M cells Concentrations of intracellular reactive oxygen species (ROS) were at low levels in a portion of S cells that abundantly expressed FoxO3a a transcription factor that regulates ROS degrading enzymes In clinical samples of HL FoxO3a was expressed in mononuclear Hodgkin cells but not in multinucleated RS cells These findings suggest that smaller cells or Hodgkin cells that show low ROS concentrations and high FoxO3a expression levels might be candidates for HL CSCs (Am J Pathol 2010 177 3081-3084 DOI 10 2353/ajpath 2010 100089)

CDCP1, a transmembrane protein with intracellular tyrosine residues which are phosphorylated upon activation, is supposed to be engaged in proliferative activities and resistance to apoptosis of cancer cells. High level of CDCP1 expression proved to be a poor prognosticator for lung adenocarcinoma. Here, expression level of CDCP1 was immunohistochemically examined in 110 cases (median age of 54.7 years) of endometrioid adenocarcinoma, and its clinical implications were evaluated. Tumor stage was stage I in 71 cases (64.5%). II in 5 (4.5%), III in 28 (25.5%), and IV in 6 (5.5%). Staining intensity of tumor cells was divided into two categories; tumor cells with no to weak and moderate to strong membrane staining. The intensity of CDCP1 expression in each case was defined by the staining of major population of cells as follows; cases with tumor cells showing no to weak and moderate to high membrane staining were categorized as CDCP1-low and CDCP1-high, respectively. Eighty-seven of 110 cases were categorized as CDCP1-high. and the remaining as CDCP1-low. Significant positive correlation was observed between low CDCP1 expression and stage (p=0.0091), relapse rate (p=0.0017), and poor prognosis (p=0.0009). Multivariate analysis revealed that low CDCP1 and advanced stage were independent poor prognostic factors for both OS and DES. As compared to cancer cells, normal endometrium continuously expressed CDCP1. These suggested that the attitude of CDCP1 in cancers of lung and endometrium was different. Different role of CDCP1 by tissues and cancers is discussed.

Podoplanin, a mucin-type transmembrane glycoprotein, is thought to be one of the cancer stem cell markers for squamous-cell carcinoma of the vulva. The objectives of the present study were to examine the role of podoplanin in esophageal squamous-cell carcinoma (ESCC). Expression of podoplanin was examined immunohistochemically in 61 cases of ESCC that had not been treated with chemotherapy or radiotherapy before surgery. Because cancer stem-cell quantities have been reported to increase with chemotherapy and radiotherapy, cases in patients who did not receive such prior therapies were included in this study. Cases with > 10% tumor cells showing signals for podoplanin were categorized as podoplanin high, and the others were classified as podoplanin low. The effects of podoplanin on the behavior of cancer cells were evaluated in ESCC cell lines in which podoplanin expression was knocked down. To examine whether podoplanin could be used as a cancer stem cell marker for ESCC, podoplanin-positive and podoplanin-negative fractions were sorted separately from the ESCC cell line and cultured. Podoplanin-positive ESCC cells yielded both podoplanin-positive and podoplanin-negative cells, whereas few cells were obtained from podoplanin-negative ESCC cells. When podoplanin expression was knocked down, ESCC cell lines became vulnerable to anticancer drugs and showed defective invasion and tumorigenic activities. Nineteen (31.1%) of 61 cases were categorized as podoplanin high. Podoplanin-high cases were correlated with T category, stage of disease, lymphatic and vascular invasion, recurrence, and prognosis of patients. Podoplanin-low cases showed better overall and disease-free survival. There is a role for podoplanin in tumorigenesis and malignant progression in ESCC.

Diffuse large B-cell lymphoma (DLBCL) involving spinal epidural space (SEDLBCL) is relatively rare, constituting 1 8% of DLBCLs in Osaka, Japan The aim of this study was to analyze SEDLBCL cases for their clinical and histopathologic findings, including an association with Epstein-Barr virus (EBV) and immunohistochemical characteristics We analyzed the clinicopathologic findings of 27 SEDLBCL cases. They consisted of 16 males and 11 females, their age ranging from 37-86 years (median 64 years). Eight patients had stage I disease, 3 had stage II, 5 had stage Ill, and 11 had stage IV Based on the staining pattern for anti-CD 10, bcl-6, and MUM-1, the cases were categorized into 17 cases of the germinal center B-cell (GCB) type and nine of the non-GCB type There was a 4%-positive rate for EBV in the tumor cells When compared to nodal DLBCL, the frequency of patients with a high performance status (PS) is higher in SEDLBCL. Compared to the DLBCL of the central nervous system (CNS). the frequency of cases with high stage, 2 or more extranodal lesions, high international prognostic index (IPI), and GCB-type is higher in SEDLBCL There were no significant differences in the histologic features between SEDLBCL and nodal/CNS DLBCL. Univariate analysis revealed that advanced stage was an unfavorable factor for overall survival (P=0.060). SEDLBCL is different from nodal and CNS DLBCL, but an association with EBV is unlikely in every group (C) 2010 Elsevier GmbH All rights reserved

A 69-year-old man underwent right hemicolectomy for colon cancer in the transverse colon in 2005. Two years after surgery, he was admitted with abdominal pain. Colonoscopy revealed a submucosal tumor of approximately 4 cm in size at the ileocolonic anastomosis site. In the biopsied samples from the anastomosis site, there was diffuse proliferation of large lymphoid cells, which were immunohistochemically positive for CD3 and CD4, but negative for CD8 and CD20. Clonality analysis of T-cell receptor-beta gene rearrangement revealed a single band, indicating monoclonal proliferation of the T-lymphocytes. Epstein-Barr virus in situ hybridization did not reveal any positive signals in any of the tumor cells. Anti-human T-lymphotropic virus-I was negative. Based on these findings, the recurrent tumor was diagnosed as peripheral T-cell lymphoma-unspecified (PTCL-u). (C) 2009 Elsevier GmbH. All rights reserved.

Cancer stem cells are a limited population of tumor cells that are thought to reconstitute whole tumors. The Hoechst dye exclusion assay revealed that tumors are composed of both a main population and a side population of cells, which are rich in cancer stem cells. NR0B1 is an orphan nuclear receptor that is expressed to a greater extent in the side population, as compared with the main population, of a lung adenocarcinoma cell fine. In this study, we investigated the role of NR0B1 in lung adenocarcinoma cells. Reduction of NR0B1expression levels in lung adenocarcinoma cell lines resulted in vulnerability to anticancer drugs and decreased abilities for invasion, in vitro colony formation, and tumorigenicity in non-obese diabetic/severe compromised immunodeficient mice. When 193 cases of lung adenocarcinoma. were immunohistochemically examined, higher levels of NR0B1 expression correlated with higher rates of lymph node metastasis and recurrence. Multivariate analysis revealed high NR0B1 expression levels, stage of the disease, and size of tumor to be independent unfavorable prognostic factors for overall and disease-free survival rates. In clinical samples, NR0B1 expression levels inversely correlated to the proportion of methylated CpG sequences around the transcription initiation site of the NR0B1 gene, suggesting the epigenetic control of NR0B1 transcription in lung adenocarcinoma. In conclusion, NR0B1 might play a role in the malignant potential of lung adenocarcinoma. (Am J Pathol 2009, 175:1235-1245; DOI: 10.2353/ajpath.2009.090010)

The aim of this study was to clarify whether diffuse large B-cell lymphoma (DLBCL) with a high number of epithelioid histiocytes (DLBCL-EH) could have distinctive clinicopathological characteristics. Clinicopathological findings in 22 cases with DLBCL-EH and, as a control, 96 cases with ordinary type of DLBCL were analyzed. There were ten men and 12 women with ages ranging from 38 to 91 (median, 64) years. The primary site was lymph node in 16 cases, extranodal organs in three, and unknown in three. Stage of disease was I in five cases, II in three, III in nine, and IV in five. Histologically, there was a diffuse proliferation of large lymphoid cells admixed with numerous clusters of epithelioid histiocytes sprinkling throughout the lesions. Immunohistochemically, the large lymphoid cells were CD20(+), CD15(-), and CD3(-) and positive for CD10, bcl-6, and MUM1 in nine (41%), eight (36%), and 12 (55%) of 22 cases, respectively. Epstein-Barr virus positive rate was higher in DLBCL-EH (23.8%) than that in ordinary DLBCL (4.5%; P < 0.05). Clonality analysis revealed monoclonal bands in all of the examined 20 cases with DLBCL-EH. Multivariate analysis revealed the prominent epithelioid reaction to be an independent factor for favorable prognosis. These findings suggest that DLBCL-EH could be a specific morphological variant of DLBCL associated with a better prognosis.

Heat shock protein 105 (HSP105) is overexpressed in various tumors and is known to protect cells from cytotoxic stimuli. The prognostic significance of HSP105 expression in cancer has not been fully evaluated. Here, HSP105 expression in lung adenocarcinoma was immunohistochemically examined in 116 patients: 68 males and 48 females with ages ranging from 38-81 (median 63) years. Tumor stage was I in 64, II in 16 and III in 36 patients. In non-cancerous tissues, HSP105 was expressed in the ciliated cells of bronchi. Tumor cells were constantly positive for HSP105, with varying intensities. The HSP105 score in each case was determined based on the staining intensity of the tumor cells occupying the widest area of cancerous tissue as follows: cases with tumor cells showing an intensity weaker than, comparable to and stronger than the bronchial epithelium were assigned a score of 1, 2 and 3, and numbered 84, 19 and 13 cases, respectively. HSP105 score was significantly correlated with the rate of recurrence and the stage of the disease. Univariate analysis showed that lymph node metastasis, disease stage and HSP105 score were unfavorable prognostic factors. Multivariate analysis revealed that lymph node metastasis and HSP105 score were independent prognostic factors for overall and disease-free Survival. HSP105 expression is useful for the prediction of prognosis in patients with lung adenocarcinoma.

CUB domain containing protein (CDCP1), a transmembrane protein with intracellular tyrosine residues which are phosphorylated upon activation, is supposed to be engaged in proliferative activities and resistance to apoptosis of cancer cells. Expression level of CDCP1 was examined in lung adenocarcinoma, and its clinical implications were evaluated. CDCP1 expression was immunohistochemically examined in lung adenocarcinoma from 200 patients. Staining intensity of cancer cells was categorized as low and high in cases with tumor cells showing no or weak and strong membrane staining, respectively. MIB-1 labeling index was also examined. There were 113 males and 87 females with median age of 63 years. Stage of disease was stage I in 144 cases (72.0%), II in 19 (9.5%), and III in 37 (18.5%). Sixty of 200 cases (30.0%) were categorized as CDCP1-high, and the remaining as CDCP1-low. Significant positive correlation was observed between CDCP1-high expression and relapse rate (P < 0.0001), poor prognosis (P < 0.0001), MIB-1 labeling index (P < 0.0001), and occurrence of lymph node metastasis (P = 0.0086). There was a statistically significant difference in disease-free survival (DFS) (P < 0.0001) and overall survival (OS) rates (P < 0.0001) between patients with CDCP1-high and CDCP1-low tumors. Univariate analysis showed that lymph node status, tumor stage, and CDCP1 expression were significant factors for both OS and DFS. Multivariate analysis revealed that only CDCP1 expression was an independent prognostic factor for both OS and DFS. CDCP1 expression level is a useful marker for prediction of patients with lung adenocarcinoma (Cancer Sci 2009; 100: 429-433).

ABCG2 is a transporter preferentially expressed in a primitive subpopulation of cells and recently reported as a surviving factor for trophoblasts. To date, manner of ABCG2 expression in lymphoid tissues is not known. Immunohistochemically, strong ABCG2 expression was found in a small proportion of plasma cells mainly located in the interfollicular space of lymphoid tissues. The number of ABCG2-high plasma cells increased in interleukin-6- (IL-6) rich lesions, such as Castleman's disease of plasma cell type. Plasma cells are subjected to endoplasmic reticulum (ER) stress when excess proteins are synthesized, and IL-6 stimulates protein synthesis. Therefore, the effect of IL-6 and ER stress on ABCG2 expression in plasma cells was examined. The expression level of ABCG2 increased by treatment with either IL-6 or ER stress inducers, and further increased with both. The promoter analysis revealed that the effect of IL-6 and ER stress inducers was mediated through the site overlapping XBP-1 and HIF-1 binding sequences. Knocked-down of ABCG2 by siRNA or ABCG2 inhibitor reduced plasma cell viability under ER stress. These suggest that ABCG2 is a surviving factor for plasma cells. To our knowledge, this is the first study reporting the effect of ER stress on ABCG2 expression.

Background Because recognizable lesions are often absent, selection of biopsy sites for diagnosis of intravascular large B-cell lymphoma (IVL) is frequently problematic. Case A 59-year-old woman was admitted with fever and general fatigue. Combined physical and roerztgenographic examinations revealed neither lymphadenopathy, hepatosplenomegaly nor Mass lesions in other organs. Serum lactate dehydrogenase level was 1,412 IU/L. There were no genital symptoms, but uterine cytologic examination revealed large cells distributed in a noncohesive pattern. These cells had a large, irregularly shaped nucleus in which several nucleoli were discernible and showed positive immunoreactivity for leukocyte common antigen. Three months after admission, neurologic symptoms appeared, and magnetic resonance imaging revealed multiple nodular lesions in, the brain. Biopsy specimens from the brain lesion showed the proliferation of large lymphoid cells filling the lumina of small vessels and Virchow-Robin's space. Immunohistochemistry revealed that the tumor cells were positive for CD20 and CD79a but negative for CD3, indicative of IVL. Conclusion Uterine cytologic and/or histologic examinations could be the choice for diagnosis of IVL, even when genital symptoms are absent. (Acta Cytol 2009;53:198-200)

Heat shock protein 105 (HSP105) is overexpressed in various tumors and is known to protect cells from cytotoxic stimuli. The prognostic significance of HSP105 expression in cancer has not been fully evaluated. Here, HSP105 expression in lung adenocarcinoma was immunohistochemically examined in 116 patients: 68 males and 48 females with ages ranging from 38-81 (median 63) years. Tumor stage was I in 64, II in 16 and III in 36 patients. In non-cancerous tissues, HSP105 was expressed in the ciliated cells of bronchi. Tumor cells were constantly positive for HSP105, with varying intensities. The HSP105 score in each case was determined based on the staining intensity of the tumor cells occupying the widest area of cancerous tissue as follows: cases with tumor cells showing an intensity weaker than, comparable to and stronger than the bronchial epithelium were assigned a score of 1, 2 and 3, and numbered 84, 19 and 13 cases, respectively. HSP105 score was significantly correlated with the rate of recurrence and the stage of the disease. Univariate analysis showed that lymph node metastasis, disease stage and HSP105 score were unfavorable prognostic factors. Multivariate analysis revealed that lymph node metastasis and HSP105 score were independent prognostic factors for overall and disease-free survival. HSP105 expression is useful for the prediction of prognosis in patients with lung adenocarcinoma.

Purpose: Our recent study revealed that CD55-high population in breast cancer cell line was resistant to apoptosis and formed colonies in vitro more efficiently than CD55-low population. The present study was conducted to examine whether CD55-high population in breast cancer cell line possesses higher turnorigenic potential in vivo and presence of CD55-high cells in breast cancer affects clinicopathologic behavior of patients. Experimental Design: CD55-high and CD55-low population was sorted from breast cancer cell line, injected into immunodeficient mice, and the resultant tumor volume was measured. CD55 expression was immunohistochemically examined in clinical samples from 74 cases with breast cancers, and cases with >1% of tumor cells showing high level of CD55 expression were categorized as CD55 high. Results: The xenotransplanted tumor volume derived from CD55-high population was significantly larger than that from CD55-low population. Fifty (67.6%) of 74 cases of breast cancer were CD55-high. A significant correlation was observed between CD55-high character and relapse rate (P < 0.001). Univariate analysis showed that tumor size (P = 0.005) and CD55 expression (P = 0.005) were unfavorable prognostic factors. Multivariate analysis revealed that the tumor size (P = 0.013) and CD55 expression (P = 0.011) were independent prognostic factors. Conclusions: CD55 play an important role in tumorigenesis of breast cancer, and presence of small population of cells with strong CD55 expression would be sufficient to predict poor prognosis of patients.

Aims: Diffuse large B-cell lymphoma (DLBCL) usually proliferates effacing lymph follicles. In occasional cases, tumour cells show an interfollicular pattern of proliferation preserving lymph follicles. The aim was to analyse clinicopathological findings in DLBCL showing an interfollicular pattern of proliferation to determine whether this type of lymphoma is a distinct entity of DLBCL. Methods and results: Clinicopathological findings in 12 cases of DLBCL showing an interfollicular pattern of proliferation [interfollicular group (IF)] were examined and compared with those in 30 cases of DLBCL with ordinary morphology [control group (CG)]. IF showed a significantly lower lactate dehydrogenase level and International Prognostic Index scores than CG (P = 0.023 and P < 0.01, respectively). The frequency of localized disease, clinical stage 1 and 2, in IF was higher than that in CG (P = 0.016). A morphologically polymorphous pattern of proliferation was found in seven of 12 cases (58.3%) in IF, which was higher than that in CG, five (16.7%) of 30 cases (P < 0.01). Clonality analysis with the polymerase chain reaction method revealed that all 11 IF cases examined showed a monoclonal pattern. Immunohistochemically, the majority (11 of 12) of IF cases showed a non-germinal centre B-cell phenotype and the frequency was higher than that in CG (P = 0.021). Conclusion: Diffuse large B-cell lymphoma with an interfollicular pattern of proliferation shows distinct clinical and pathological findings from ordinary DLBCL.

Clinicopathological and immunophenotypical characteristics in 24 patients with diffuse large B-cell lymphoma (DLBCL) under 30 years of age in Osaka, Japan were examined, and the results compared to those of DLBCL patients aged over 40 years in Osaka and of young DLBCL patients in Western countries. The level of LDH and IPI score at initial diagnosis were significantly lower in young than older patients. The sex ratio (M:F) and age range (median) in the young and older groups were 1.18 and 11-30 (24.8) years and 1.59 and 42-87 (62.4) years, respectively. Extranodal presentation was higher in the young group (83.3% versus 60.0%, P < 0.05). Based on immunophenotyping with anti-CD10, bcl-6, and MUM1 antibodies, the cases were categorized as germinal center B-cell (GCB) (CD10+ or CD10-, bcl-6+, MlU1+) or non-GCB phenotype. The frequency of GCB type was significantly lower in the young group than older group (25% vs. 54%, P < 0.05), and much lower than that reported for young patients in Western countries. In situ hybridization revealed one of the young patients to be positive for Epstein-Barr virus (EBV). In the older group, none of 31 cases showed EBV positivity. Three year event-free and overall survival rates of young patients were better than those of the older patients, although not significantly different. DLBCL in the young in Japan is characterized by a much lower frequency of the GCB phenotype compared to that in Western countries.

Granulocyte colony-stimulating factor (G-CSF)-producing malignancies are thought to be rare and associated with advanced disease and poor prognosis. Here, we report on a 77-year-old patient with G-CSF-producing gastric cancer. We observed this patient from the stage prior to the diagnosis of gastric cancer when leukocyte count was normal to the stage of advanced disease associated with remarkable leukocytosis. Immunohistochemical analysis demonstrated G-CSF expression in the advanced-stage, poorly differentiated adenocarcinoma, but not in the early-stage, well-differentiated adenocarcinoma. G-CSF receptor was not detected to be expressed in the advanced-stage tumor. Based on these results it appears that a histological change in the tumor may influence G-CSF production and the concomitant rapid progression in gastric cancer.

Cancer stem cells are supposed to be resistant to apoptosis, but information for this is quite limited. Cancer stem cells are usually isolated as dye-effluxing cells with Hoechst 33342 staining, called side-population (SP) cells. Because Hoechst 33342 dye itself induces apoptosis, the SP cells isolated by such method are not suitable for evaluation of apoptosis. For accurate assessment, SP cells must be isolated without Hoechst 33342. Here, we found that CD55 was highly expressed in SP cells of two mammary gland carcinoma cell lines. Then, the high expression of CD55 was used for isolation of cancer stem cells among mammary carcinoma cell lines as a surrogate character. Cells expressing high level of CD55 (CD55(hi)) were resistant to apoptosis induced by serum depletion as in the case of SP cells. In ceramide-inducing apoptosis, CD55(hi) cells showed high tolerance. Antiapoptotic molecules such as Bcl-2 were abundantly expressed in both SP cells and CD55(hi) cells. These findings indicated that SP cells as revealed to be CD55(hi) cells were tolerant to apoptosis. The high expression of CD55 may be a useful character for SP cells in evaluating their functions. (c) 2007 Elsevier Inc. All rights reserved.

Recent studies have identified vimentin, a type III intermediate filament, among genes differentially expressed in tumours with more invasive features, suggesting an association between vimentin and tumour progression. The aim of this study, was to investigate whether vimentin expression in colon cancer tissue is of clinical relevance. We performed immunostaining in 142 colorectal cancer (CRC) samples and quantified the amount of vimentin expression using computer-assisted image analysis. Vimentin expression in the tumour stroma of CRC was associated with shorter survival. Overall survival in the high vimentin expression group was 71.2% compared with 90.4% in the low-expression group (P = 0.002), whereas disease-free survival for the high-expression group was 62.7% compared with 86.7% for the low-expression group (P = 0.001). Furthermore, the prognostic power of vimentin for disease recurrence was maintained in both stage II and III CRC. Multivariate analysis suggested that vimentin was a better prognostic indicator for disease recurrence (risk ratio 3.5) than the widely used lymph node status (risk ratio 2.2). Vimentin expression in the tumour stroma may reflect a higher malignant potential of the tumour and may be a useful predictive marker for disease recurrence in CRC patients.

Objective. Individuals with rheumatoid arthritis (RA) with or without methotrexate (MTX) medication occasionally develop lymphoproliferative disorders (MTX-LPD and non-MTX-LPD, respectively). The hyperimmune state of RA itself or the immunosuppressive state induced by MTX administration might contribute to development of LPD. Our objective was to characterize MTX-LPD in comparison to non-MTX-LPD and sporadic LPD in patients with RA. Methods. We compared MTX-LPD to non-MTX-LPD and sporadic LPD by evaluating 48 cases of MTX-LPD, 28 non-MTX-LPD, and 150 sporadic LPD. Results. Later onset age of LPD and female predominance were evident in patients with RA-LPD compared to sporadic LPD. The interval between the diagnosis of RA and LPD in MTX-LPD (median 132 mo) was significantly shorter than that in non-MTX-LPD (240 mo). The frequency of diffuse large B cell lymphoma (DLBCL) and positive rate of Epstein-Barr virus (EBV) in RA-LPD was significantly higher than in sporadic LPD (57.9% vs 42.7%, 27.6% vs 9.9%, respectively). After withdrawal of MTX, 11 of the MTX-LPD cases showed a spontaneous regression of tumors. The 5-year survival rate in RA-LPD (59.2%) was significantly worse than that in sporadic LPD (74.6%). Conclusion. The majority of cases of RA-LPD show similar clinicopathological characteristics irrespective of MTX medication, except for spontaneous regression of LPD after withdrawal of MTX in MTX-LPD, and a shorter interval between the diagnosis of RA and LPD in MTX-LPD than in non-MTX-LPD. RA-LPD cases showed younger age of onset, female predominance, unfavorable prognosis, and higher frequencies of DLBCL and EBV positivity compared to sporadic LPD.

Mediastinal lymphangiomatosis in a 70-year-old woman was diagnosed on a medical checkup. The tumor was resistant to sclerotherapy with OK432 or bleomycin. The patient continued on a downhill course and died approximately 3 years after the initial diagnosis. Autopsy revealed a large tumor mass occupying the anterior mediastinum and firmly adhered to the pericardium and the pleura. The tumor consisted of two intermingled lesions: dilated vessels lined with D2-40-positive lymphatic endothelium and CD5-positive atypical cell nests with focal keratinization. The former was diagnosed as lymphangiomatosis and the latter as thymic squamous cell carcinoma. Vascular endothelial growth factor (VEGF)-C, a growth factor for lymphatic endothelial cells, was expressed by the carcinoma, and VEGF-C receptor was expressed by the endothelium of lymphangiomatosis. These findings suggested that VEGF-C derived from the thymic carcinoma induced the lymphangiomatosis lesion in a paracrine manner.

CDCP1, a novel stem cell marker, is expressed in hematopoietic cell line K562 but not in Jurkat. When CDCP1 promoter was transfected exogenously, Jurkat showed comparable promoter activity with K562, suggesting that the factor to enhance transcription was present but interfered to function in Jurkat. The reporter assay and si-RNA-mediated knockdown experiment revealed that zfp67, a zinc-finger protein, enhanced CDCP1 transcription. Amount of zfp67 in Jurkat was comparable with K562, but chromatin immunoprecipitation showed that zfp67 bound to CDCP1 promoter in K562 but not in Jurkat. There are CpG sequences around the promoter of CDCP1, which were heavily methylated in Jurkat but not in K562. Addition of demethylating reagent to Jurkat induced CDCP1 expression, and increased the zfp67 binding to CDCP1 promoter. Among normal hematopoietic cells such as CD34(+)CD38(-) cells, lymphocytes and granulocytes, inverse correlation between proportion of methylated CpG sequences and CDCP1 expression level was found. Demethylation of CpG sequences in lymphocytes, in which CpG sequences were heavily methylated, induced CDCP1 expression and its expression level further increased through zfp67 overexpression. The methylation of DNA appeared to regulate the cell-type-specific expression of CDCP1 through the control of interaction between chromatin DNA and transcription factors.

CDCP1 is a novel stem cell marker that is expressed in several types of cancer. The mechanisms by which CDCP1 expression is regulated, and the clinical implications of this marker, have not been clarified. In this report, we examine the epigenetic-regulation of CDCP1 expression in cell lines and clinical samples from patients with-breast cancer. Many CpG sequences were localized around the transcription initiation site of CDCP1. These CpG motifs were found to be poorly methylated in cell lines with high levels of CDCP1 expression and heavily methylated in cell lines with low levels of CDCP1 expression. The in vitro methylation of CpG sites decreased CDCP1 promoter activity, and the addition of a demethylating reagent restored activity. In 25 breast cancer samples, an inverse correlation was noted between the CDCP1 expression level and the proportion of methylated to nonmethylated CpG sites. Tumours with high-level CDCP1 expression showed higher levels of proliferation, as revealed by immunohistochemical detection of the MIB-1 antigen, than tumours with low-level CDCP1 expression. These findings indicate that the expression of CDCP1 is regulated by methylation of its promoter region in tumours. CDCP1 expression may prove to be useful in the further characterization of cancers. Copyright (c) 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Pyothorax-associated lymphoma (PAL) is a unique lymphoma developing in the pleural cavity after long-standing pyothorax. They are diffuse large B-cell lymphomas (DLBCLs), frequently with immunoblastic morphology, and show a strong association with Epstein-Barr virus (EBV) infection. In this study, cDNA microarray analysis was performed in six cases with PAL and 12 with nodal DLBCL. Among 5516 informative genes, 348 displayed more than 2-fold difference (higher or lower) of expression level between PAL and nodal DLBCL (P<0.001). These genes are known to be involved in apoptosis, interferon response, and signal transcluction. One of the most differentially expressed genes, IF127 (interferona-inducible protein 27) was subjected to quantitative RT-PCIR analysis, and increased expression of IF127 was confirmed. Overexpression of IF127 was also found in cell lines derived from PAL, but not in other lymphoid cell lines. This study shows that PAL is a distinctive subtype of DLBCL not only in its clinical presentation, but also in its molecular profile.