坂本 洋右

Circulating tumor cells (CTCs) and/or their relating molecules are promising determinants during the course of cancer treatment, especially for post-therapeutic monitoring. We recently reported the clinical relevance of detecting circulating tumor-associated mutant mitochondrial DNAs (mut-mtDNAs) at three different regions including the displacement loop, 12S-rRNA and 16S-rRNA in oral squamous cell carcinomas (OSCCs). In the present study, to further investigate if the other mut-mtDNAs have novel efficiency for detecting potential tumoral micrometastasis, mut-mtDNAs on the ND2 and ND3 regions of the genome in 240 clinical samples from patients with OSCC were assessed in vitro and in vivo by quantitative real-time PCR combined with high-resolution melting curve analysis. Furthermore, the clinical relevance was evaluated by the area under the receiver operating characteristic curve (AUC) analysis. Three discrete sequence variations were identified in OSCC derived cell lines at the regions of ND2 (T:A to C:G at position 5108) and ND3 (A:T to G:C at position 10397 and C:G to T:A at position 10400), whereas no mutation was observed in normal control human normal oral keratinocytes. In OSCC patients examined, the presence of mut-mtDNAs in serum during the postoperative period accurately predicted poor prognoses (ND2 AUC, 0.761; ND3 AUC, 0.704). The data presented here provide a novel approach for detecting the circulating mut-mtDNAs that are promising molecular markers for evaluating tumoral micrometastasis in OSCCs.

Persephin (PSPN) is a neurotrophic factor of the glial cell line-derived neurotrophic factor (GDNF) family that promotes survival of multiple populations of neurons. Little is known about the relevance of PSPN in human malignancy including oral squamous cell carcinoma (OSCC). This study was undertaken to evaluate PSPN mRNA and protein expression by analyzing cellular proliferation and the cell cycle in PSPN knockdown cells in vitro. PSPN mRNA and protein were significantly (P < 0.05) up-regulated in OSCC-derived cells compared with human normal oral keratinocytes (n = 7). Cellular proliferation decreased significantly (P < 0.05) in PSPN knockdown cells with reduced receptor tyrosine kinase (RTK) signaling, and cell-cycle arrest at the G1 phase resulted from up-regulation of the cyclin-dependent kinase inhibitors (p21(Cip1) , p27(Kip1) , p15(INK4B) , and p16(INK4A) ). Furthermore, the PSPN protein expression in 101 primary OSCCs was significantly (P < 0.05) higher than in normal counterparts. Among the clinical variables analyzed, overexpression of PSPN also was related closely (P < 0.05) to tumoral size. Our results suggested that PSPN is a possible key regulator of OSCC progression via PSPN-RET-mitogen-activated protein kinase activation and that PSPN overexpression may have diagnostic potential for OSCC.

BACKGROUND: Adenosine A2b receptor (ADORA2B) encodes an adenosine receptor that is a member of the G protein-coupled receptor superfamily. This integral membrane protein stimulates adenylate cyclase activity in the presence of adenosine. Little is known about the relevance of ADORA2B to human malignancy including oral squamous cell carcinoma (OSCC). We aimed to characterize the expression state and function of ADORA2B in OSCC. METHODS: The ADORA2B expression levels in nine OSCC-derived cells were analyzed by quantitative reverse transcriptase-polymerase chain reaction and immunoblotting analyses. Using an ADORA2B knockdown model, we assessed cellular proliferation and expression of hypoxia-inducible factor1α (HIF-1α). We examined the adenosine receptor expression profile under both normoxic and hypoxic conditions in the OSCC-derived cells. In addition to in vitro data, the clinical correlation between the ADORA2B expression levels in primary OSCCs (n = 100 patients) and the clinicopathological status by immunohistochemistry (IHC) also was evaluated. RESULTS: ADORA2B mRNA and protein were up-regulated significantly (p < 0.05) in seven OSCC-derived cells compared with human normal oral keratinocytes. Suppression of ADORA2B expression with shRNA significantly (p < 0.05) inhibited cellular proliferation compared with the control cells. HIF-1α also was down-regulated in ADORA2B knockdown OSCC cells. During hypoxia, ADORA2B expression was induced significantly (p < 0.05) in the mRNA and protein after 24 hours of incubation in OSCC-derived cells. IHC showed that ADORA2B expression in primary OSCCs was significantly (p < 0.05) greater than in the normal oral counterparts and that ADORA2B-positive OSCCs were correlated closely (p < 0.05) with tumoral size. CONCLUSION: Our results suggested that ADORA2B controls cellular proliferation via HIF-1α activation, indicating that ADORA2B may be a key regulator of tumoral progression in OSCCs.

Inflammatory abnormalities have been implicated in the pathogenesis of various human diseases, including cancer. Interleukin-1 receptor antagonist (IL1RN) is a potent anti-inflammatory molecule that modulates the biological activity of the proinflammatory cytokine, interleukin-1. The aim of this study was to examine the expression of IL1RN in oral squamous cell carcinomas (OSCCs), and to determine its clinical significance. Expression levels of IL1RN in matched normal and tumor specimens from 39 OSCCs were evaluated using real-time quantitative polymerase chain reaction methods, and immunohistochemical analysis. Protein expression of IL1RN was also examined in 18 oral premalignant lesions (OPLs). Expression of IL1RN mRNA was significantly downregulated in OSCCs compared with normal tissues. Decreased expression of IL1RN protein was also observed in OPLs and OSCCs. The IL1RN expression level was lower in the OPL cases with severe dysplasia compared to those with mild/moderate dysplasia. Significantly downregulated IL1RN expression was observed in all OSCC lesion sites examined when compared with the matched normal tissues. However, the decreased level of IL1RN expression did not correspond with tumor progression. Noteworthy, IL1RN expression was higher in the advanced OSCC cases (T3/T4) compared to early cases (T1/T2). Among OSCC samples, relatively higher IL1RN expression was associated with active tumor development in the OSCCs occurring in the buccal mucosa, oral floor, fauces and gingiva, but not the tongue. These data suggest that IL1RN may exhibit opposing characteristics in oral malignancies depending on the stage of cancer development, suppressing early carcinogenic events, yet promoting tumor development in some lesion sites. Thus, IL1RN could represent a reliable biomarker for the early diagnosis of OSCCs. Furthermore, IL1RN may possess unknown and complex functions in the developed OSCC.

We reported previously that decorin (DCN) is significantly up-regulated in chemoresistant cancer cell lines. DCN is a small leucine-rich proteoglycan that exists and functions in stromal and epithelial cells. Accumulating evidence suggests that DCN affects the biology of several types of cancer by directly/indirectly targeting the signaling molecules involved in cell growth, survival, metastasis, and angiogenesis, however, the molecular mechanisms of DCN in chemoresistance and its clinical relevance are still unknown. Here we assumed that DCN silencing cells increase chemosusceptibility to S-1, consisted of tegafur, prodrug of 5-fluorouracil. We first established DCN knockdown transfectants derived from oral cancer cells for following experiments including chemosusceptibility assay to S-1. In addition to the in vitro data, DCN knockdown zenografting tumors in nude mice demonstrate decreasing cell proliferation and increasing apoptosis with dephosphorylation of AKT after S-1 chemotherapy. We also investigated whether DCN expression predicts the clinical responses of neoadjuvant chemotherapy (NAC) using S-1 (S-1 NAC) for oral cancer patients. Immunohistochemistry data in the preoperative biopsy samples was analyzed to determine the cut-off point for status of DCN expression by receiver operating curve analysis. Interestingly, low DCN expression was observed in five (83%) of six cases with complete responses to S-1 NAC, and in one (10%) case of 10 cases with stable/progressive disease, indicating that S-1 chemosensitivity is dramatically effective in oral cancer patients with low DCN expression compared with high DCN expression. Our findings suggest that DCN is a key regulator for chemoresistant mechanisms, and is a predictive immunomarker of the response to S-1 NAC and patient prognosis.

Myofibroma is a benign tumor characterized by the proliferation of spindle cells originating from myofibroblasts. This tumor, common in infants, rarely occurs in the oral cavity of adults. Owing to its clinical and pathological characteristics, myofibroma has often been misdiagnosed, leading to inappropriate treatment choices. We report here a rare case of a myofibroma occurring in the maxillary bone of a 57-year-old woman. A rapidly growing mass was observed in the anterior maxilla. Imaging examinations revealed a radiolucent, tumor-like solitary lesion. Nuclear medicine scans revealed hyperintense accumulations at the anterior maxilla. Myofibroma was strongly suggested and no malignant finding was observed on biopsy. Since the lesion was solitary, it was excised completely by surgery. The histopathological findings indicated that the lesion mainly comprised bundles of spindle cells with a central hemangiopericytoma-like vascular pattern. Immunohistochemical staining showed the lesion to be positive for vimentin, α-smooth muscle actin and S-100 and negative for desmin. Thus, a definitive diagnosis of myofibroma was made. No recurrence was observed at the 2-year postoperative follow-up. The present case suggests that pathological examination including immunohistochemical analysis is essential for definitive diagnosis and for avoiding misdiagnosis and the consequent unnecessary therapies.

BACKGROUND: The relevance of lysophosphatidylcholine acyltransferase1 (LPCAT1), a cytosolic enzyme in the remodeling pathway of phosphatidylcholine metabolism, in oral squamous cell carcinoma (OSCC) is unknown. We investigated LPCAT1 expression and its functional mechanism in OSCCs. METHODS: We analyzed LPCAT1 mRNA and protein expression levels in OSCC-derived cell lines. Immunohistochemistry was performed to identify correlations between LPCAT1 expression levels and primary OSCCs clinicopathological status. We established LPCAT1 knockdown models of the OSCC-derived cell lines (SAS, Ca9-22) for functional analysis and examined the association between LPCAT1 expression and the platelet-activating factor (PAF) concentration and PAF-receptor (PAFR) expression. RESULTS: LPCAT1 mRNA and protein were up-regulated significantly (p<0.05) in OSCC-derived cell lines compared with human normal oral keratinocytes. Immunohistochemistry showed significantly (p<0.05) elevated LPCAT1 expression in primary OSCCs compared with normal counterparts and a strong correlation between LPCAT1-positive OSCCs and tumoral size and regional lymph node metastasis. In LPCAT1 knockdown cells, cellular proliferation and invasiveness decreased significantly (p<0.05); cellular migration was inhibited compared with control cells. Down-regulation of LPCAT1 resulted in a decreased intercellular PAF concentration and PAFR expression. CONCLUSION: LPCAT1 was overexpressed in OSCCs and correlated with cellular invasiveness and migration. LPCAT1 may contribute to tumoral growth and metastasis in oral cancer.

BACKGROUND: Semaphorins (SEMAs) consist of a large family of secreted and membrane-anchored proteins that are important in neuronal pathfinding and axon guidance in selected areas of the developing nervous system. Of them, SEMA7A has been reported to have a chemotactic activity in neurogenesis and to be an immunomodulator; however, little is known about the relevance of SEMA7A in the behaviors of oral squamous cell carcinoma (OSCC). METHODS: We evaluated SEMA7A expression in OSCC-derived cell lines and primary OSCC samples using quantitative reverse transcriptase-polymerase chain reaction, immunoblotting, and semiquantitative immunohistochemistry (sq-IHC). In addition, SEMA7A knockdown cells (shSEMA7A cells) were used for functional experiments, including cellular proliferation, invasiveness, and migration assays. We also analyzed the clinical correlation between SEMA7A status and clinical behaviors in patients with OSCC. RESULTS: SEMA7A mRNA and protein were up-regulated significantly (P<0.05) in OSCC-derived cell lines compared with human normal oral keratinocytes. The shSEMA7A cells showed decreased cellular growth by cell-cycle arrest at the G1 phase, resulting from up-regulation of cyclin-dependent kinase inhibitors (p21Cip1 and p27Kip1) and down-regulation of cyclins (cyclin D1, cyclin E) and cyclin-dependent kinases (CDK2, CDK4, and CDK6); and decreased invasiveness and migration activities by reduced secretion of matrix metalloproteases (MMPs) (MMP-2, proMMP-2, pro-MMP-9), and expression of membrane type 1- MMP (MT1-MMP). We also found inactivation of the extracellular regulated kinase 1/2 and AKT pathways, an upstream molecule of cell-cycle arrest at the G1 phase, and reduced secretion of MMPs in shSEMA7A cells. sq-IHC showed that SEMA7A expression in the primary OSCCs was significantly (P = 0.001) greater than that in normal counterparts and was correlated with primary tumoral size (P = 0.0254) and regional lymph node metastasis (P = 0.0002). CONCLUSION: Our data provide evidence for an essential role of SEMA7A in tumoral growth and metastasis in OSCC and indicated that SEMA7A may play a potential diagnostic/therapeutic target for use in patients with OSCC.

Multiple myeloma is a malignant neoplasm of plasma cells characterized by proliferation of a single clone of abnormal immunoglobulin-secreting plasma cells. Since the amount of hemopoietic bone marrow is decreased in the maxilla, oral manifestations of multiple myeloma are less common in the maxilla than in the mandible. We report the case of 33-year-old Japanese man who presented with a mass in the right maxillary alveolar region. Computed tomography and magnetic resonance images showed a soft tissue mass in the right maxilla eroding the anterior and lateral walls of the maxillary sinus and extending into the buccal space. The biopsy results, imaging, and laboratory investigations led to the diagnosis of multiple myeloma. This case report suggests that oral surgeons and dentists should properly address oral manifestations as first indications of multiple myeloma.

Sarcomatoid renal cell carcinoma (SRCC) is a rare kidney tumor with rapid growth and a poor prognosis. Here we report a case of metastatic SRCC of the right masseter region with trismus as an initial symptom from SRCC of kidney. Computed tomography imaging presented masses in the right masseter region and right kidney. Positron emission tomography also showed widespread 18F-fluorodeoxyglucose uptake masses in their regions with other organs and lymph nodes. Fine-needle aspiration (FNA) cytology for the right masseter mass showed suspicious findings of glandular cell tumor. We then took a biopsy sample from right kidney and diagnosed the specimen as SRCC histopathologically. Since FNA samples were similar to the SRCC, the right masseter region was predicted to be metastatic tumor from the SRCC of right kidney. Although the patient underwent systemic chemotherapy for SRCC with several anticancer agents, such as sunitinib, gemcitabine, and doxorubicin for SRCC, he died of respiratory failure 10 months after the initial chemotherapy.

The human kallikrein-related peptidase family is comprised of 15 serine protease genes on chromosome 19q13.4. Our previous microarray analyses showed that the gene kallikrein-related peptidase 13 (KLK13) was down-regulated in oral squamous cell carcinoma (OSCC) cell lines. We evaluated the expression status of KLK13 in primary OSCCs and performed functional molecular experiments in OSCC cell lines. In 102 primary tumors studied, KLK13 expression significantly (P < 0.05) decreased compared with matched normal counterparts. Interestingly, KLK13-negative cases correlated significantly (P < 0.05) with regional lymph node metastasis. In vitro, cells overexpressing KLK13 (oeKLK13) had decreased invasiveness and motility and up-regulation of adhesion molecules (E-cadherin, α-catenin, β-catenin, junction plakoglobin, plakophilin4, desmocollin2, desmoglein3, and desmoplakin) compared with control cells. A rescue experiment that transfected oeKLK13 cells with siRNA against KLK13 restored invasiveness and migration activities with down-regulated adhesion molecules. Based on our results, we concluded that KLK13 may play an important role in regulating cellular migration and invasiveness, making the loss of KLK13 a potential biomarker for early detection of lymph node metastasis in OSCCs.

The objective of this study was to elucidate the clinical characteristics of uncommon head and neck malignancies, such as non-squamous cell carcinoma (SCC), in order to improve patient outcomes. A total of 463 head and neck malignancies were retrospectively analyzed, with 43 cases (9.3%) diagnosed as non-SCC. The overall survival rate of patients with adenoid cystic carcinoma was significantly worse compared to that of patients with SCC. The 5-year survival rates were <50% for patients with malignant melanoma, adenocarcinoma, small-cell carcinoma and sarcomas. Distant metastasis to the lung was frequently observed in cases with a poor outcome. Non-SCC malignancies treated without surgery were associated with a worse outcome. Some non-SCC patients had a poor prognosis and distant metastasis was associated with an unsatisfactory outcome. Timely treatment and control of distant metastasis are essential and surgical treatment should be prioritized in non-SCC cases to improve patient outcomes.

No definitive therapy exists to treat human metastatic tumors. We reported previously that down-regulation of Lin-7C is essential for metastasis of human squamous cell carcinomas (hSCCs). In this study, we investigated the chemical restoration of Lin-7C expression and demonstrated its effectiveness for suppressing the metastatic potential in human cancer cells. Ingenuity Pathway Analysis (IPA) identified candidate chemical agents, i.e., apomorphine, caffeine, risperidone, quetiapine, and mirtazapine. Among them, mirtazapine, an antagonist of HTR2C, an upstream molecule of Lin-7C, caused substantial up-regulation of the Lin-7C/β-catenin pathway in a metastatic hSCC cell line and human melanoma-derived cell line in vitro, and up-regulation did not contribute to cellular proliferation. Moreover, the antimetastatic effect of mirtazapine in these metastatic cell lines in vivo also was evident in multiple organs of immunodeficient mice with no marked side effects. The current data offer novel information for further study of antimetastatic activity in association with enhanced Lin-7C/β-catenin pathway activation with mirtazapine.

In the oral and maxillofacial regions, epidermoid cysts usually develop in the floor of the mouth and rarely in other sites. We describe a case of an epidermoid cyst arising in the right maxillary sinus. A 27-year-old man was referred to our department for swelling in the right buccal region. Computed tomography showed a dense soft-tissue mass that extended widely into the maxillary sinus, resulting in thinning of the cortical bone of the exterior wall of the maxillary sinus. The cyst was enucleated via the intraoral approach with the patient under general anesthesia. Histopathologically, the wall was lined with a thin layer of keratinizing squamous epithelium and fibroma connective tissue with no skin appendages. The diagnosis was an epidermoid cyst. There has been no evidence of recurrence during the 3-year follow-up. © 2012 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI.