Published papers

Tissue factor (TF) is a transmembrane glycoprotein that plays roles in the blood coagulation and intracellular signaling pathways, and has also been suggested to modulate the biological behavior of cancer cells. In order to examine the clinicopathologic significance of TF expression in pancreatic ductal adenocarcinoma, TF expression was determined by immunohistochemistry using a newly raised anti-TF monoclonal antibody in 113 patients who had undergone surgical resection of pancreatic ductal adenocarcinoma. According to the incidence of tumor cell immunopositivity, patients were divided into "negative TF (0%), "weak TF (<25%), or "high TF (25% or more) groups, which accounted for 11.6% (n = 13), 44.2% (n = 50), and 44.2% (n = 50) of the total, respectively. Increased TF expression was correlated with the extent of the primary tumor (P = 0.0043), lymph node metastasis (P = 0,0043), lymphatic distant metastasis (P 0.0039), advanced tumor-node-metastasis stage (P = 0.0002),and high tumor grade (P 0,0164). Multivariate analysis using the Cox proportional hazards model showed that high TF expression was an independent negative predictor for survival (hazard ratio, 2.014; P = 0.0076). Moreover, patients with TF-negative tumors had a significantly better prognosis even if lymph node metastasis was present (P < 0.0001). We also showed that TF knockdown by RNA interference suppressed the invasiveness of a pancreatic adenocarcinoma cell line in vitro. These results indicate that TF expression may contribute to the aggressiveness of pancreatic ductal adenocarcinoma by stimulating tumor invasiveness, and that evaluation of the primary tumor for TF expression may identify patients with a poor prognosis.

The E-cadherin-mediated cell adhesion system is frequently inactivated by multiple mechanisms and is involved in tumor progression in many types of cancer. Recently we have reported a novel cell membrane glycoprotein, dysadherin, which has an anti-cell-cell adhesion function and downregulates E-cadherin. Expressions of dysadherin and E-cadherin were investigated immunohistochemically in 91 patients with squamous cell carcinoma of the tongue to determine the correlation between the 2 molecules and their associations with the clinicopathologic features of the tumors and with patient survival. Dysadherin was expressed at the cell membranes of many cancer cells. Twenty-five percent of the tumors showed dysadherin immunopositivity in more than 50% of the cancer cells. Sixty-nine percent of the tumors showed reduced E-cadherin immunopositivity. There was an inverse correlation between dysadherin expression and E-cadherin expression (P = 0.0001). Increased dysadherin expression was significantly correlated with an infiltrative type of growth pattern (P = 0.001), high tumor-node-metastasis (TNM) stage (P= 0.024), and poor patient survival (P = 0.003). After adjusting for growth pattern, TNM stage, and other clinicopathologic features, increased dysadherin expression and reduced E-cadherin expression were both significant predictors of poor survival (P = 0.0006). Increased dysadherin expression is a significant indicator of poor prognosis in patients with squamous cell carcinoma of the tongue.

While metastasis to the pancreas is uncommon, it may occur from renal cell carcinomas (RCCs). We here present a case of pancreatic metastasis from RCC extending into the main pancreatic duct (MPD) in a 66-year-old Japanese man. The patient had a history of RCC treated with a radical nephrectomy 17 years previously and was found to have a mass similar to2 cm in diameter in the body of the pancreas on radiological images. The patient was suspected of having pancreatic metastasis from RCC and underwent a distal pancreatectomy with splenectomy. Histologically, the tumor consisted of cells arranged in trabecular and alveolar structures with clear or eosinophilic granular cytoplasm, compatible with a metastatic RCC. The pancreatic tumor extended into the MPD with the stream of pancreatic juice. This condition is similar to RCC extension into the renal vein and the inferior vena cava. In conclusion, although extension into the MPD may be rare, such a growth pattern may be characteristic of metastases from RCCs.

Serous cystic neoplasm (SCN) of the pancreas is a benign epithelial neoplasm, except in extremely rare malignant cases. Development of SCN in tissues other than the pancreas has been never reported. Here we present the first reported case of SCN in an intrapancreatic accessory spleen (IPAS). A 54-year-old female patient with von Hippel-Lindau (VHL) syndrome was found to have pancreatic tail mass. Pathologically the 25-mm solid mass was an IPAS showing proliferation of clear cuboidal tumor cells without atypia, forming numerous small cysts. The tumor cells were rich in cytoplasmic glycogen and distributed in the splenic tissue almost diffusely. Immunohistochemically, tumor cells were positive for cytokeratins, MUC6, and neuron-specific enolase, and negative for neuroendocrine markers. From these findings, we diagnosed the lesion as SCN in IPAS. This tumor is suggested to develop as a VHL-associated SCN from coexisting pancreatic tissue in IPAS rather than as a metastatic tumor.

Loss of ABO blood group antigen expression has been reported in transitional cell carcinoma ( TCC) of the bladder. Synthesis of the ABO blood group antigen was genetically determined by allelic variants of the ABO gene assigned on 9q34.1. We analyzed loss of heterozygosity ( LOH) and promoter hypermethylation of the ABO gene in TCC and compared them with alterations of A antigen expression in TCC, dysplasia and normal urothelium. A total of 81 samples of TCC of the bladder obtained from transurethral resection ( TUR) ( n = 44) and radical cystectomy ( n = 37) were examined. Expression of the A antigen was evaluated by immunohistochemical staining ( IHC) using anti-A antigen monoclonal antibody. LOH of the ABO gene locus was examined by blunt-end single-strand DNA conformational polymorphism ( SSCP) analysis using flouresence-based auto sequencer. Promoter hypermethylation of the ABO gene were examined by bisulfite PCR-SSCP ( BiPS) analysis and/or methylation-specific PCR ( MSP). Loss of A allele and/or hypermethylation were significantly associated with abnormal expression of the A antigen in cases undergoing TUR ( P = 0.02) and radical cystectomy ( P = 0.0005). For the analysis of the concomitant dysplasia in 23 cases with TCC of the bladder, the expression of the A antigen was maintained, regardless of the A allelic loss or methylation status in the tumor. In conclusion, A allelic loss and hypermethylation in the promoter region of the ABO gene showed significant correlation with reduction of A antigen expression in TCC, while the expression of the A antigen is maintained in concomitant dysplasia or normal urothelium, suggesting that loss of the ABO gene and/or its promoter hypermethylation is a specific marker for TCC.

Alteration of DNA methylation is one of the most consistent epigenctic changes in human cancers. DNA methyltransferase (DNMT) 1 is a major enzyme that determines genomic methylation patterns. In order to understand the significance of mutations of the DNMT1 gene during human carcinogenesis, we performed polymerase chain reaction-single strand conformation polymorphism analysis using 46 oligonucleotide primer sets for all 40 coding exons and the 5-flanking region (450 bp) of the DNMT1 gene in 29 colorectal cancers, 32 stomach cancers, 40 hepatocellular carcinomas (HCCs) and a corresponding sample of non-cancerous tissue from each case. Mutations in coding exons of the DNMT1 gene were detected in two (7%) of the colorectal cancers: they consisted of one-base deletion resulting in deletion of the whole catalytic domain and a point mutation resulting in a single amino acid substitution. No stomach cancers or HCCs showed mutations in the coding exons of the DNMT1 gene. No mutation in the 5'-flanking region of the DNMT1 gene was detected in any of the colorectal and stomach cancers or HCCs. These data suggest that mutational inactivation of the DNMT1 gene that potentially causes a genome-wide alteration of DNA methylation status may be a rare event during human carcinogenesis. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

We analysed gene-expression profiles in 15 surgical specimens of conventional, papillary, and chromophobe renal cell carcinomas (RCCs) using high-density oligonucleotide arrays. From about 12 000 genes targeted by the array, 67 were upregulated specifically in each histological type of RCC. The oncogene KIT was one of the genes whose expression was upregulated specifically in chromophobe RCCs. Immunohistochemical analysis demonstrated the KIT gene product on the cell membrane of chromophobe RCC in all cases, although it was not detected in conventional RCCs or non-neoplastic kidneys except for weak staining in the cytoplasm of renal tubules. These results suggest that each histological subtype of RCC has a unique gene-expression profile, and in particular indicates for the first time that KIT could be a useful marker for chromophobe RCC. As overexpression of KIT might be involved in tumor growth, KIT could be a new therapeutic target in this special type of RCC.

DNA hypomethylation on pericentromeric satellite regions is an early and frequent event associated with heterochromatin instability during human hepatocarcinogenesis. A DNA methyltransferase, DNMT3b, is required for methylation on pericentromeric satellite regions during mouse development. To clarify the molecular mechanism underlying DNA hypomethylation on pericentromeric satellite regions during human hepatocarcinogenesis, we examined mutations of the DNMT3b gene and mRNA expression levels of splice variants of DNMT3b in noncancerous liver tissues showing chronic hepatitis and cirrhosis, which are considered to be precancerous conditions, and in hepatocellular carcinomas (HCCs). Mutation of the DNMT3b gene was not found in HCCs. Overexpression of DNMT3b4, a splice variant of DNMT3b lacking conserved methyltransferase motifs IX and X, significantly correlated with DNA hypomethylation on pericentromeric satellite regions in precancerous conditions and HCCs (P = 0.0001). In particular, the ratio of expression of DNMT3b4 to that of DNMT3b3, which is the major splice variant in normal liver tissues and retains conserved methyltransferase motifs I, IV, VI, IX, and X, showed significant correlation with DNA hypomethylation (P = 0.009). Transfection of human epithelial 293 cells with DNMT3b4 cDNA induced DNA demethylation on satellite 2 in pericentromeric heterochromatin DNA. These results suggest that overexpression of DNMT3b4, which may lack DNA methyltransferase activity and compete with DNMT3b3 for targeting to pericentromeric satellite regions, results in DNA hypomethylation on these regions, even in precancerous stages, and plays a critical role in human hepatocarcinogenesis by inducing chromosomal instability.

Objective: We attempted to identify tumor-related genes whose expression is affected by DNA methylation and that participate in the determination of the biological characteristics of human cancers. Methods and materials: We used the differential display method in ten 5-azacytidine-treated human cancer cell lines. Time-dependent induction of mRNA expression of Wip1. TROP2, B4-2 protein, BRCA-2 region transcription unit CG005, cofilin, ROCK, CD44, and interferon-inducible protein 6-16 was observed during 5-azacytidine treatment. We then evaluated the mRNA expression of these genes in 26 stomach and 32 colorectal cancers and 44 hepatocellular carcinomas (HCCs) and in the corresponding non-cancerous tissues. Results Significantly reduced rn RNA expression of Wip1, B4-2, and cofilin in stomach cancers, of Wip1, B4-2, BRCA-2 region transcription unit CG005, cofilin, and ROCK in colorectal cancers, and of TROP2, B4-2, and BRCA-2 region transcription unit CG005 in HCCs, was observed in comparison with the corresponding non-cancerous tissues, whereas overexpression of TROP2 was detected in colorectal cancers. Reduced expression of Wip1 and BRCA-2 region transcription unit CG005 was significantly correlated with poorer differentiation of HCCs, and mRNA expression of these genes was significantly reduced in HCCs associated with portal vein involvement compared with HCCs without such involvement. Expression of TROP2 mRNA was significantly higher in chronically diseased liver from HCC patients compared with histologically normal liver, but was reduced in progressed HCCs. Reduced expression of B4-2 protein was observed in association with hepatitis B virus infection of HCC patients. Conclusions: These data suggest that DNA methylation may play a role in human multistage carcinogenesis through direct or indirect regulation of multiple tumor-related genes.

Aberrant DNA methylation has been shown to play an important role during multistage carcinogenesis in various human organs. The aim of the present study was to evaluate the significance of DNA methyltransferase 1 (DNMT1) protein expression during pancreatic carcinogenesis. Immunohistochemical analysis of DNMT1 in 48 peripheral pancreatic duct epithelia showing no remarkable histological findings without an inflammatory background (DE), 54 peripheral pancreatic duct epithelia with an inflammatory background (DEI), 188 pancreatic intraepithelial neoplasias (PanIN), and 220 areas of invasive ductal carcinoma from surgical specimens resected from 100 patients, was carried out. The average incidence of DNMT1 immunoreactivity increased progressively from DE to DEI (P = 0.003), from DE and DEI to PanIN (P < 0.0001), among PanIN with different grades of dysplasia (from PanIN I to PanIN II, P = 0.0012), from PanIN to invasive ductal carcinomas (P < 0.0001) and among invasive ductal carcinomas with different grades of histological differentiation (from well or moderately to poorly differentiated adenocarcinomas, P < 0.0001). High-level DNMT1 protein expression in invasive ductal carcinomas was correlated significantly with an advanced t category (P=0.0224) and an advanced stage (P=0.0294). Moreover, patients with invasive ductal carcinomas showing high-level DNMT1 protein expression had a poorer outcome (P = 0.0469). These data suggest that increased DNMT1 protein expression participates in multistage pancreatic carcinogenesis from the precancerous stage to malignant progression of ductal carcinomas and may be a biological predictor of poor prognosis.

We evaluated the significance of aberrant DNA methyltransferase I (DNMT1) protein expression during gastric carcinogenesis. The protein expression of DNMT1, Muc2, human gastric mucin, E-cadherin, and proliferating cell nuclear antigen was examined immunohistochemically in gastric cancers and corresponding noncancerous mucosae from 134 patients. The DNA methylation status of the CpG islands of the p16, human MutL homologue I (hMLH1), E-cadherin, and thrombospondin-1 (THBS-1) genes and the methylated in tumor (MINT)-1, -2, -12, and -31 clones was examined by methylation-specific polymerase chain reaction and combined bisulfite restriction enzyme analysis. Epstein-Barr virus (EBV) infection was detected by in situ hybridization. Nuclear immunoreactivity for DNMT1 was not detected in any of the noncancerous epithelia, except in proliferative zones (positive internal control), but was found in 97 (72%) of the gastric cancers. DNMT1 overexpression correlated significantly with poorer tumor differentiation (P < 0.001), but not with the phenotype (gastric type versus intestinal type) of the cancer cells. it also correlated significantly with DNA hypermethylation of the CpG islands of the hMLH1 (P = 0.024) and THBS-1 genes (P = 0.043), and with the CpG island methylator phenotype in the gastric cancers (P = 0.007). Reduced E-cadherin expression correlated significantly with poorer tumor differentiation (P = 0.002), DNA hypermethylation of the E-cadherin gene (P < 0.001) and DNMT1 overexpression (P = 0.014). DNMT1 overexpression was also associated with EBV infection (a potential etiological factor in gastric carcinogenesis) but not with the proliferative activity of the cancer cells as indicated by the proliferating cell nuclear antigen-labeling index. These results suggest that DNMT1 overexpression may not be just a secondary effect of increased cancer cell proliferative activity, but may be associated with EBV infection and other etiological factors during gastric carcinogenesis. Furthermore, DNMT1 may play a significant role in the development of poorly differentiated gastric cancers by inducing frequent DNA hypermethylation of multiple CpG islands.

Laminin 5 plays an important role in cell migration during tumor invasion and tissue remodeling. However, previous studies have not clarified whether laminin 5 beta3 chain is coexpressed with laminin 5 gamma 2 chain in cancer cells. The present immunohistochemical study investigated the distribution of the laminin 5 beta3 and gamma 2 chains in 20 cases of squamous cell carcinoma of the tongue and 17 cases of colorectal carcinoma. Laminin 5 beta3 and gamma 2 chains were expressed in the cytoplasm of tumor cells. Tumor cells at the cancer-stromal interface and at the invasive front frequently showed immunopositivity for laminin 5 beta3 and gamma 2 chains in both squamous cell carcinoma of the tongue and colorectal carcinoma. Furthermore, strong expressions of these two proteins were observed in cancer cells invading in a scattered manner. Laminin 5 beta3 expression correlated significantly with laminin 5 gamma 2 expression in 20 cases of squamous cell carcinoma of the tongue (P=0.0002) and 17 cases of colorectal carcinoma (P<0.0001). These results suggest that in squamous cell carcinoma of the tongue and colorectal carcinoma, laminin 5 gamma 2 chain and beta3 chain are both important in the invasiveness of cancer cells.

Alteration of DNA methylation is one of the most consistent epigenetic changes in human cancers. DNA methyltransferase (DNMT) 1 is a major enzyme involved in establishing genomic methylation patterns. Most of the studies concerning DNMT1 expression in human cancers have been performed only at the mRNA level. To directly examine DNMT1 protein expression levels during human hepatocarcinogenesis, 16 histologically normal liver tissues, 51 noncancerous liver tissues exhibiting chronic hepatitis or cirrhosis, which are considered to be precancerous conditions, and 53 hepatocellular carcinomas (HCCs) were subjected to immunohistochemic examination. If more than 20% of the cells exhibited nuclear DNMT1 staining, the tissue sample was considered to be DNMT1-positive. DNMT1 immunoreactivity was observed in 23 (43%) of the HCCs, but in none (0%) of the histologically normal liver or noncancerous liver tissues exhibiting chronic hepatitis or cirrhosis. The incidence of increased DNMT1 protein expression in HCCs correlated significantly with poor tumor differentiation (p = 0.0006) and portal vein involvement (p = 0.0002). Moreover, the recurrence-free (p = 0.0001) and overall (p < 0.0001) survival rates of patients with HCCs exhibiting increased DNMT1 protein expression were significantly lower than those of patients with HCCs that did not exhibit increased expression. Increased DNMT1 protein expression may play a critical role in the malignant progression of HCCs and be a biologic predictor of both HCC recurrence and a poor prognosis in HCC patients. (C) 2003 Wiley-Liss, Inc.