白澤 浩

Neuroblastomas present a wide variety of clinical and biological behaviors, which are reflected by the heterogeneous expressions of protooncogenes related to the neuronal differentiation and amplification of the N-myc gene. High expression of trk A and Ha-ras in neuroblastomas has been shown to be associated with an excellent patient outcome. We have previously reported that neuron-specific src mRNA was increased in chemically differentiated neuroblastoma cell lines and in clinically observed neuroblastomas without N-myc amplification, In the present study, to clarify both the value of neuronal c-srcN2 expression as a prognostic indicator and the significance of the coexpression of these photooncogenes, we examined the expression of 3 alternatively spliced src, trk A and Ha-res in neuroblastoma tissues from 60 patients by competitive RNA-polymerase chain reaction (PCR). The restates indicate that protooncogene expression in neuroblastomas correlated with a favorable outcome for c-srcN2 and trk A. N-myc gene was amplified exclusively in tumors with low levels of trk A. Low expression of c-srcN2 and trk A might thus characterize different aggressive phenotypes due to different signal transduction pathways of neural differentiation in neuroblastoma. The combined analyses for c-srcN2 and trk A expression by RNA-BCR should provide information about the biological phenotype of a neuroblastoma within a short period of time after obtaining tumor material. (C) 1998 Wiley-Liss, Inc.

The polymorphism of p53 gene at codon 72 consisting of either arginine (Arg)- or proline (Pro)-encoded allele is suggested to be associated with the susceptibility of tobacco-related lung cancer. In this study we examined the polymorphism of 224 non-small cell lung cancer (NSCLC) patients and that of 303 control persons with a polymerase chain reaction method and found that Pro-allele carriers were significantly more frequent in those patients who smoked and were affected at a younger age (<65) (P<0.05). We also investigated whether the mutational alterations of this gene could be influenced by the genotype. The overall mutation rate of 114 NSCLC patients examined with a single-strand conformation polymorphism method was 31%, which agreed with previous reports. However, the mutation rate was significantly increased in those patients who smoked and were affected at a younger age (<65) (P<0.05). Although the Pro-allele carriers among the smoker patients showed higher mutation rate than the Arg/Arg homozygotes, the difference between the genotypes had marginal significance (0.1<P<0.05) and was statistically insignificant, if the study was confined to younger patients. Thus, the present data cannot confirm a possible association of the p53 polymorphism with its mutation rate regarding smoking-related lung cancer.

Nineteen cutaneous and mucocutaneous papillomas, as well as 29 oral and 25 non-oral squamous cell carcinomas of dogs were analyzed immunohistologically for the presence of papillomavirus (PV)-antigens. Canine oral papillomavirus (COPV)-DNA was detected in formalin-fixed, paraffin-embedded tissues by polymerase chain reaction (PCR) and non-radioactive in situ hybridization (ISH). Furthermore, the expression of the tumor suppressor protein p53 was investigated. PV-antigens were detectable in more than 50% of the oral and cutaneous papillomas, while no PV-antigens could be demonstrated in venereal papillomas. One squamous cell carcinoma was PV-antigen positive, Only two cutaneous papillomas of the head showed a strong p53-specific immunostaining, while overexpressed p53 was detectable in approximately 35% of all squamous cell carcinomas. It was possible to amplify fragments of the E6, E7 and L1 gene by polymerase chain reaction (PCR) from five of eight oral and from five of eight cutaneous papillomas as well as from three oral squamous cell carcinomas. Nine of 10 papillomas showed a strong nucleus-associated hybridization signal typical for COPV-DNA. In three squamous cell carcinomas COPV-DNA was located in nests of the epithelial tumor cells surrounding 'horn pearls' or disseminated in the carcinoma tissue. These observations support the view that COPV may also induce non-oral papillomas in the dog and confirm the opinion that a progression of viral papillomas into carcinomas in dogs may occur. (C) 1998 Elsevier Science B.V.

Advanced neuroblastoma and malignant liver tumor are representative childhood cancers for which combined chemotherapy including cisplatin and doxorubicin is routinely performed. The prognosis of patients with tumors which develop multiple drug resistance (MDR) is unfavorable. To elucidate the role of multidrug resistance-associated protein (MRP) and canalicular multispecific organic anion transporter (cMOAT) in the clinical behavior of the tumors, we examined 42 neuroblastomas and 10 malignant liver tumors for the expressions of MRP and cMOAT by quantitative RNA-polymerase chain reaction (PCR). The amplification and expression of N-myc oncogene in the neuroblastomas were also investigated. We found a close association between MRP and N-myc expression in each neurobtastoma sample but no significant relationship between MRP expression and the patients' outcome. The forced expression of N-myc failed to enhance the expression of MRP in N-myc transfected neuroblastoma cell lines. cMOAT was rarely expressed in the neuroblastomas, but was frequently expressed in the malignant liver tumors. The expression of MRP and cMOAT in the childhood liver tumors was more common and higher, especially in advanced cases with a poor outcome, than that observed in normal liver or in 9 hepatocellular carcinomas from adult patients. The enhanced expression of these genes might be characteristic of childhood malignant liver tumors and related to their clinical chemoresistance.

Neuroblastomas present a wide variety of clinical and biological behaviors, which are reflected by the heterogeneous expressions of protooncogenes related to the neuronal differentiation and amplification of the N-myc gene. High expression of trk A and Ha-ras in neuroblastomas has been shown to be associated with an excellent patient outcome. We have previously reported that neuron-specific src mRNA was increased in chemically differentiated neuroblastoma cell lines and in clinically observed neuroblastomas without N-myc amplification. In the present study, to clarify both the value of neuronal c-srcN2 expression as a prognostic indicator and the significance of the coexpression of these protooncogenes, we examined the expression of 3 alternatively spliced src, trk A and Ha-ras in neuroblastoma tissues from 60 patients by competitive RNA-polymerase chain reaction (PCR). The results indicate that protooncogene expression in neuroblastomas correlated with a favorable outcome for c-srcN2 and trk A. N-myc gene was amplified exclusively in tumors with low levels of trk A. Low expression of c-srcN2 and trk A might thus characterize different aggressive phenotypes due to different signal transduction pathways of neural differentiation in neuroblastoma. The combined analyses for c-srcN2 and trk A expression by RNA- PCR should provide information about the biological phenotype of a neuroblastoma within a short period of time after obtaining tumor material.

Although human papillomavirus type 16 (HPV16) E6 protein has a transcription-modulatory activity for a wide variety of viral promoters, a cellular target for this activity of E6 has not Set been identified, In this study, using differential hybridization, we identified a mouse fibronectin (FN) gene as a putative cellular target whose expression is up-regulated by E6. Chloramphenicol acetyltransferase (CAT) assays with mouse and rat FN promoter-CAT fusion constructs indicated that HPV16 E6 transactivates the FN promoters in a p53-independent manner, Deletion and site-specific mutation analyses revealed that transactivation by HPV16 E6 depends upon a cyclic AMP response element (CRE) located at -160 relative to the start site of transcription. Gel retardation assays demonstrated that nuclear extracts from the HPV16 E6-expressing cells, compared to those from parental 10T1/2 cells, have increased binding activity to the CRE, Antibodies against c-Jun and ATF-2 disrupted this binding activity. These data indicate that HPV16 E6 transcriptionally modulates FN gene expression via the CRE by inducing the binding of the protein complexes, probably including c-Jun and ATF-2, to the CRE.

This report demonstrates that normal human fibroblasts can be immortalized by the introduction of HPV-M E6-E7 genes. We designed zinc-inducible expression plasmids with HPV-16 E6, E7 or both. Each plasmid was introduced into normal human fibroblasts (TIG-3 cells) using lipofection methods. Only transfectants with the HPV-16 E6-E7 zinc-inducible expression plasmid, which were cultured in medium supplemented with 100 mu M ZnSO4, overcame crisis and could be cultured over 200 population doubling levels (PDLs), These cell lines showed the reactivation of telomerase after crisis, and morphological alterations were also observed.

The myc proto-oncogene family plays an important role in the control of cellular growth and differentiation. Mxil, one of the Max-associated proteins, has been known to have an antagonistic action on Myc activity. The mxil mRNA increased during growth inhibition and differentiation, and decreased with serum stimulation in mammal cell lines. We have also found an AAAAC polymorphic repeat in the 3' non-coding region of the human mxil cDNAs and a difference between the mxil mRNA half-lives in some different cell lines.

Using a differential hybridization technique, we have identified a mouse cellular gene, high mobility group protein HMG-I(Y), whose expression is up-regulated by the E6 protein of human papillomavirus (HPV) type 16. This gene was overexpressed in Eh-expressing mouse 10T1/2 cells, but not in G418-resistant 10T1/2 cells. The expression of the HMG-I(Y) gene was up-regulated by the transient expression of E6 from a zinc-inducible human metallothionein-IIA gene promoter. Expression was found to be more efficient at a confluent cell density than at a subconfluent cell density. The up-regulation of HMG-I(Y) gene expression by E6, in particular at a confluent cell density, may be part of an altered genetic program in host cells infected with HPV-16.

The mechanism by which the E6 protein of human papillomavirus type 16 (HPV-16) transactivates heterologous virus promoters has not been established. In this study, the involvement of p53-mediated transcriptional repression in transactivation by the HPV-16 E6 protein was examined using several virus promoters. HPV-16 E6 transactivated the TATA box-containing simian virus 40 early promoter and the Rous sarcoma virus long terminal repeat in p53-containing cells but not in p53-deficient cells. In contrast, the adenovirus E2 promoter was transactivated both in p53-containing and p53-deficient cells. These results indicate that the transactivation activity of the HPV-16 E6 protein is mediated by p53-dependent and promoter-specific p53-independent pathways.

Rotaviruses were detected via electron microscopy in fecal specimens collected from school children during an outbreak of diarrhea and from a sporadic case in 1993 in Japan. All of the viruses were found to belong to human group C rotavirus by reverse passive hemagglutination assay (RPHA). These viruses replicated well in a human colon carcinoma (CaCo-2) cell line cultured in the presence of trypsin (4 mu g/ml). This report demonstrates that human group C rotaviruses can be propagated efficiently in a cell line cultured in the presence of trypsin. The infected cells did not show any apparent cytopathic changes. However, virus was detected in the cell cytoplasm by immunofluorescence (IF) staining and in the culture supernatant by RPHA. On the basis of immune electron microscopy (IEM), virus particles collected from infected CaCo-2 cell cultures were confirmed to aggregate specifically with anti-human group C rotavirus antibody. The electrophoretic patterns of RNA segments extracted from viral particles found in the fecal specimens or infected cells were identical to those of human group C rotavirus. These results indicated that human group C rotaviruses were the causal agent of the diarrhea outbreak. (C) 1996 Wiley-Liss, Inc.

Interleukin-6 (IL-6) is a pleiotropic cytokine that is not only a mediator in major immunologic reactions but also a growth factor of keratinocytes. We studied the IL-6 secretion in vitro of 15 human cell lines derived from both squamous cell carcinoma (SCC) and adenocarcinoma of the uterine cervix. Four of the eight well differentiated SCC secreted a large amount (>1500 pg/48 h/10(6) cells) of IL-6 in nude mice. In contrast, poorly differentiated SCC cell lines and all of the 7 adenocarcinoma cell lines secreted a small amount (<500 pg/48 h/10(6) cells of IL-6). The expression of IL-6 mRNA of the cell lines correlated well with their IL-6 secretion potential. However, the expression of IL-6 receptor did not correlate with the IL-6 secretory potential. We also studied the IL-6 secretion of freshly isolated normal squamous epithelium and of dysplastic epithelium. In culture, two normal squamous epithelia secreted a large amount (>2000 pg/48 h/10(6) cells), whereas 8 dysplasia epithelia secreted an extremely small amount (<10 pg/48 h/10(6) cells). About one-third of patients with SCC had a raised serum IL-6 value. IL-6 production may help to differentiate between SCC and adenocarcinoma of the uterine cervix. IL-6 regulation seems to change in the course of SCC carcinogenesis.

Using a differential hybridization technique, we have identified a mouse cellular gene, high mobility group protein HMG-I(Y), whose expression is up- regulated by the E6 protein of human papillomavirus (HPV) type 16. This gene was overexpressed in E6-expressing mouse 10T1 2 cells, but not in G418- resistant 10T1 2 cells. The expression of the HMG-I(Y) gene was up-regulated by the transient expression of E6 from a zinc-inducible human metallothionein-HA gene promoter. Expression was found to be more efficient at a confluent cell density than at a subconfluent cell density. The up- regulation of HMG-I(Y) gene expression by E6, in particular at a confluent cell density, may be part of an altered genetic program in host cells infected with HPV-16.

Human papillomavirus (HPV) type 6a genomes with a large deletion in their L1 open reading frames (ORF) were found in two of five recurrent cases of laryngeal papilloma. One of these mutant HPVs had a 186 base pair (bp) deletion near the N-terminus end of the L1 ORF, which encodes a major capsid protein. The other had a 454 bp deletion at the C-terminus end of L1 at which is located a nuclear localising signal (NLS). No other large deletion or insertion was found in the remaining regions of all five HPV6a genomes. The laryngeal papillomas which harboured the mutant viruses showed typical hyperplasia and pathological changes as observed in tumours induced by the wild-type virus. The biological significance of the two large deletions in the late region of HPV6a associated with laryngeal papilloma is discussed. (C) 1995 Wiley-Liss, Inc.

The DNA genome of a canine oral papillomavirus (COPV) was completely sequenced and found to consist of 8607 base pairs, which were the longest of all known papillomaviruses (PVs). Its organization was similar to that of other PVs except that it lacked early gene 5 (E5) and possessed a unique long noncoding region (L-NCR) between the end of the early genes and the beginning of the late genes. COPV also possessed a short noncoding region (S-NCR) which contained a putative upper regulatory region (URR), which is commonly found in PVs. The L-NCR did not show any similarity to known PV DNAs nor other DNA sequences in the GenBank database. Nucleotide sequence analysis of COPV showed that it was closely related to human papillomavirus type 1 (HPV 1) and animal PVs associated with cutaneous lesions in rabbit, European elk, deer and cow as we reported previously.

To examine whether human papillomavirus (HPV) DNA is associated with esophageal cancer, frozen and paraffin-embedded neoplasms of the upper aerodigestive tract, including esophageal cancer, were investigated. DNA obtained from frozen specimens and cell lines were analyzed by both polymerase chain reaction (PCR) and Southern blot hybridization. DNA from paraffn-embedded samples were analyzed strictly by PCR. DNA of HPV types 6 and 11 was detected in papillomas of the upper respiratory tract at >50%. However, HPV DNA was infrequently detected in specimens from the upper digestive tract (31 esophageal cancers and 2 esophageal carcinoma-derived cell lines), even by PCR at a sensitivity of 0.1 copy number per cell. These results suggest that the etiologic significance of HPV infection in esophageal cancer is negligible.

The cloning and sequencing of the murine Mxi1 gene encoding Mxi1, one of Max-associated proteins, is described. Murine and human sequences showed 87.9% nucleotide (nt) and 90.3% amino acid (aa) sequence homology, whereas murine and zebra fish sequences showed 67.2% nt and 67.8% aa sequence homology.

The HeLa cell line which is one of the most popular cell lines was shown to be suitable for isolation of types A (H3N2 and B influenza viruses from throat washings of patients. Sixty-nine and 67 out of 147 throat washings taken from patients during the period from January to April, 1994, were positive for influenza A virus in HeLa cells and MDCK cells, respectively. Seven out of 10 throat washings taken between January and March, 1993, were positive for influenza B virus in MDCK. Of these 7, 4 were also positive for HeLa cells.

Human papillomavirus (HPV) type 6a genomes with a large deletion in their L1 open reading frames (ORF) were found in two of five recurrent cases of laryngeal papilloma. One of these mutant HPVs had a 186 base pair (bp) deletion near the N‐terminus end of the L1 ORF, which encodes a major capsid protein. The other had a 454 bp deletion at the C‐terminus end of L1 at which is located a nuclear localising signal (NLS). No other large deletion or insertion was found in the remaining regions of all five HPV6a genomes. The laryngeal papillomas which harboured the mutant viruses showed typical hyperplasia and pathological changes as observed in tumours induced by the wild‐type virus. The biological significance of the two large deletions in the late region of HPV6a associated with laryngeal papilloma is discussed. © Wiley‐Liss, Inc. Copyright © 1995 Wiley‐Liss, Inc., A Wiley Company

Neuron-specific src mRNA, which is expressed in human brain tissue by alternative splicing, is associated with neural differentiation. Neuronal c-srcNI expression may be associated with the ability of neuroblastomas to mature; furthermore, c-srcN2 mRNA is induced in chemically differentiated neuroblastoma cells in vitro. The prognosis of a patient with a neuroblastoma is strongly affected by the ability of the tumor to differentiate in vivo. In order to clarify the relationship between neuronal src mRNA expression and the clinical outcome of a neuroblastoma, we analyzed the expression of src mRNA in neuroblastoma tissues from 28 patients by SI-nuclease-protection assay. N-myc gene amplification was also examined by Southern blot hybridization. The clinical significance of neuronal src mRNA expression and its relevance to N-myc gene amplification was also investigated. A high ratio (more than 10%) of c-srcN2 mRNA expression was observed in all early-stage tumors and in advanced neuroblastomas with a favorable prognosis. In contrast, in advanced neuroblastomas with an aggressive clinical phenotype, c-srcN2 mRNA expression ws found at a low ratio (below 10%). Genome amplification of the N-myc gene and expression of c-srcN2 mRNAs were inversely correlated. When combined with other prognostic markers such as N-myc gene amplification, the expression of c-srcN2 mRNA may be a new biological marker to predict the prognosis of patients with neuroblastomas.

The E6 gene of human papillomavirus type 16 (HPV16) has the potential to encode full-length as well as truncated E6 proteins (E6*I and E6*II) by alternative splicings. Spliced ORF E6*I is considered to facilitate the translation of the neighboring E7 ORF; however, the putative E6*I protein is suspected to be functionless. In this study, the transcription-modulatory functions of full-length E6 and E6*I proteins were examined using cDNAs from a cervical carcinoma cell line. E6*I cDNA was able to trans-activate the autologous P97 promoter and the heterologous adenovirus E2 promoter. Full-length E6 was found to trans-activate the heterologous promoter, but repress transcription from the autologous P97 promoter. The transcription-modulatory functions of full-length E6 and E6*I proteins suggested that transcriptional regulation of HPVs associated with mucosal malignant lesions is complex. (C) 1994 academic Press, Inc.

Previous studies have indicated that the splice patterns of E6-transcripts of human papillomavirus type-16 (HPV-16) are uniform. The splice ratios of E6-transcripts, however, seem to be variable in several HPV-positive cell lines, suggesting that cellular factors may affect the alternative splicing of E6-transcripts. To test this hypothesis, the splice ratios of E6-transcripts in various HPV-16 E6-expressing cell lines derived from CV-1 and 10T1/2 cells were quantitatively evaluated by S1 nuclease protection assays. The splice ratios varied among cell lines derived from the same parental lines, indicating that factors specific to cell-type do not play a major role in alternative splicing. The splice ratios appeared to be low in cell lines which prominently expressed longer than expected E6-transcripts indicating that the structure of the E6-transcript affects its splicing. Analysis of the expression patterns of COS-1 cells which transiently expressed various E6-transcript constructs suggested that structure was a factor in determining alternative splicing.

The frequency of integration with human papillomavirus (HPV) and its genotypes in Japanese penile cancer was examined with relation to p53 gene mutations using polymerase chain reaction amplification. Tissues were obtained from 13 patients (eight from freshly frozen and five from paraffin-embedded samples). HPV DNA was detected in seven out of the 13 (54%), and their genotypes were type 16 in four, type 31 in one and type 33 in two cases. Neither HPV-detected nor -undetected tissues showed mutated alterations in exons 4-9 of p53 genes. The results suggest HPV to be, at least to some extent, involved in the oncogenesis of penile cancer, and that p53 gene mutations may not correlate with the development of penile cancer.