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E Tahara

Publications and source records attributed to E Tahara.

At least 91 records · Page 5Linked to original sources
PubMed1998

Expression of telomerase catalytic component, telomerase reverse transcriptase, in human gastric carcinomas.

Telomerase activity is believed to be crucial for cellular immortality, which is considered to participate in the development of a majority of human cancers. Human telomerase reverse transcriptase (TERT) has recently been identified as a catalytic subunit of telomerase. We examined the expression of TERT and other telomerase components such as human telomerase RNA component (hTR, encoded by TERC) and human telomerase-associated protein (TEP1) by reverse transcription-polymerase chain reaction in human gastric carcinomas and non-neoplastic mucosa, in addition to measuring the telomerase activity. Of 20 gastric carcinomas examined, 18 (90%) and 18 (90%) showed increased expression of TERT and higher telomerase activity in comparison with corresponding non-neoplastic mucosa, respectively. Increased expression of hTR/TERC was also observed in 15 (75%) of the gastric carcinomas. Immunohistochemically, strong expression of TERT protein was detected in the nuclei of the tumor cells of all carcinoma tissues, while the expression of TERT in non-neoplastic mucosal cells as well as stromal elements (except lymphocytes) was weak or negative. These findings suggest that increased TERT expression associated with telomerase activity may serve as a novel marker for the diagnosis of stomach cancer.

Aged↗
PubMed1998

In situ mRNA hybridization technique for analysis of human telomerase RNA in gastric precancerous and cancerous lesions.

Telomerase, the ribonucleoprotein enzyme that elongates telomerase, is repressed in normal somatic cells but is reactivated during tumor progression. The purpose of this study was to investigate the localization of human telomerase RNA (hTR) expression in human gastric precancerous and cancerous lesions by using in situ mRNA hybridization (ISH) with avidin-biotin staining. We also examined telomerase activity in these lesions by using hybridization protection assay connected with a telomeric repeat amplification protocol (TRAP/HPA). Analyzed tissue samples were as follows; 132 cases of chronic atrophic gastritis without intestinal metaplasia, 115 incomplete-type intestinal metaplasias, 40 complete-type intestinal metaplasias, 23 hyperplastic polyps, 23 tubular adenomas and 26 adenocarcinomas. In ISH analysis, high levels of hTR expression were observed preferentially in the nuclei at the single-cell level. hTR-expressing cells in carcinomas and adenomas were significantly more frequent than those of the other lesions (P < 0.001). The expression pattern of hTR in carcinoma and adenoma tissues was heterogeneous and similar intratumor heterogeneity was detected in Ki-67 immunoreactivity. Infiltrating lymphocytes in tissue also exhibited high levels of hTR expression. In TRAP/HPA analysis, carcinomas had significantly more frequent positivity for telomerase activity and a higher level of telomerase activity than the other lesions (P < 0.05). However, the amount of telomerase activity did not parallel the expression level of hTR. Our data suggest that hTR expression increases in the early stages of stomach carcinogenesis and that sufficient synthesis of hTR is a prerequisite for telomerase reactivation in tumorigenesis.

Humans↗
PubMed1998

Expression of vascular endothelial growth factor in human gastric carcinomas.

Vascular endothelial growth factor (VEGF), also known as vascular permeability factor, is a secreted protein which may play a pivotal role in tumor-associated microvascular angiogenesis and hyperpermeability. The expression of mRNA for VEGF was examined in eight gastric carcinoma cell lines and 30 gastric carcinoma tissues as well as corresponding normal mucosa. All the cell lines expressed VEGF mRNA at various levels that correlated well with the amounts of VEGF secreted into the condition medium. The expression of VEGF mRNA by TMK-1 cells was increased by the treatment of epidermal growth factor (EGF) or interleukin-1alpha (IL-1alpha), whereas it was decreased by the treatment of interferon-beta (IFN-beta). In gastric carcinoma tissues, the level of VEGF mRNA in primary tumors was higher than that in the corresponding normal mucosas in six (46%) of 13 well-differentiated adenocarcinomas and in two (12%) of 17 poorly differentiated adenocarcinomas, respectively. Vessel counts in well-differentiated adenocarcinomas had a tendency to be higher than those in poorly differentiated adenocarcinomas. In well-differentiated adenocarcinomas, the levels of VEGF mRNA expression tended to be higher in carcinomas of advanced stage than in early stage carcinomas. Both in situ mRNA hybridization and immunohistochemistry demonstrated the presence of VEGF expression within the tumor cells. These results suggest that VEGF may confer angiogenesis and progression of human gastric carcinomas, especially of the well-differentiated type.

Adenocarcinoma↗
PubMed1998

Reduced expression of the CD44 variant exons in oral squamous cell carcinoma and its relationship to metastasis.

In the present study, we examined the expression of CD44 variant exons in human oral squamous cell carcinoma (OSCC). Of ten cell lines from OSCCs, two (KB and H357), as well as the HeLa cell line, failed to express CD44 variant exons. In surgical specimens, all normal mucosa expressed CD44v9 (both mRNA and protein). Of 40 primary OSCCs, 19 (47.5%) showed downregulation of CD44v9, which correlated with tumor cell differentiation, primary metastasis to lymph nodes and secondary metastasis to lymph nodes. The results suggest that the downregulation of CD44v9 may play a role in lymphatic metastasis of OSCC and changes in its expression may be a useful diagnostic tool to determine the metastatic potential of OSCC to lymph nodes. Moreover, three cell lines that failed to express CD44 variant exons might become a useful experimental model to study the role of variant exons in the progression of OSCC.

Blotting, Western↗
PubMed1998

Mutation of the transforming growth factor-beta type II receptor gene is a rare event in human sporadic gastric carcinomas.

Mutations of the transforming growth factor-beta type II receptor (TGF-beta RII) gene have been detected in several human cancers. However, mutation analysis of coding sequences of TGF-beta RII in gastric carcinomas has not yet been fully elucidated. We performed PCR-SSCP analysis and direct DNA sequencing of the entire coding region of TGF- RII in 38 human sporadic gastric cancers and 8 gastric cancer cell lines. Mutations of the TGF-beta RII were detected in two tumors and three cell lines. Two tumors had one base deletion in the polyadenine tract in exon 3, the cystein-rich extracellular domain. Three cell lines had a silent mutation in the kinase domain located in exon 4. Polymorphisms were detected in introns 2 and 3. An a/g polymorphism was observed at the seventh base in intron 2 and an a/t polymorphism was observed at the fourth to last base in intron 3. There were no mutations in exons 1, 2, 5, 6 and 7. These results indicate that the polyadenine tract in the TGF-beta RII is a mutational hot spot in human gastric cancer. However, these results also suggest that mutations of the gene are rare events in human sporadic gastric cancer.

DNA Primers↗
PubMed1998

Frequent microsatellite instability and loss of heterozygosity in the region including BRCA1 (17q21) in young patients with gastric cancer.

It is known that nearly 5% of gastric carcinomas arise under the age of 40. To elucidate genetic alterations in these patients, we performed studies using microsatellite assay in 27 gastric cancers under 35 years of age, composed of 5 well and 22 poorly differentiated adenocarcinomas. We detected replication errors (RERs) in 18 (67%) of 27 tumors, but no germline mutation in DNA mismatch repair genes (hMLH1 and hMSH2), except fory 3 somatic mutations in the hMLH1 gene. Loss of heterozygosity (LOH) at D17S855, located on chromosome 17q21 (BRCA1), was detected in 8 (40%) of 20 informative cases. In 12 (44%) of 27 cases, LOH on chromosome 17q12-21 including the BRCA1 was found in several neighboring markers in this region, while no mutation was found in the BRCA1 gene. Four (40%) of 10 scirrhous type gastric cancers exhibited wide allelic deletions on chromosome 17q12-21. These results overall suggest that young gastric cancer patients display highly frequent micro-satellite instability that might be due to defect of DNA repair system rather than hMLH1 and hMSH2. In addition, chromosome 17q12-21 including BRCA1 locus may contain a candidate for tumor suppressor gene, particularly in scirrhous type gastric cancers arising in young patients.

Adult↗
PubMed1998

Expression of CD44 containing variant exon 9 (CD44v9) in gastric adenomas and adenocarcinomas: relation to the proliferation and progression.

The expression of CD44 splice variant containing exon 14 (variant exon 9: CD44v9) was examined immunohistochemically in non-neoplastic mucosa, adenoma and adenocarcinoma of the stomach and analyzed the relation with the expression of Ki-67 antigen and p53 protein. In non-neoplastic gastric mucosa, basolateral membrane of the epithelial cells in the pyloric glands showed the expression of CD44v9. The epithelial cells in the intestinal metaplastic mucosa of the stomach sometimes expressed CD44v9. In the neoplastic lesions, the expression of CD44v9 was detected in 20% (34/170) of the adenomas and 28% (132/478) of the adenocarcinomas, respectively. The incidence of CD44v9 expression did not differ among histological type of gastric carcinoma. Twelve per cent of the adenocarcinomas showed strong expression of CD44v9, whereas non of the adenomas did. The incidence of CD44v9 expression was significantly higher in carcinomas invading into muscularis propria or the cases of stages 3 and 4 in comparison with that in carcinomas limited to submucosa or the stages 1 and 2 cases (p<0.05). The incidence of positive cases was higher in carcinomas with lymph node metastasis than those without metastasis (p<0.05). The expression of CD44v9 was significantly correlated with the expression of Ki-67 (p<0.05). It was also correlated with the expression of p53 protein in the tumor cells (p<0.01). These findings overall suggest that the expression of CD44v9 may be associated with the development as well as progression of the gastric carcinomas.

Adenocarcinoma↗
PubMed1998

Expression of interleukin-8 correlates with vascularity in human gastric carcinomas.

Interleukin (IL)-8 is a multifunctional cytokine that can stimulate the division of endothelial cells. We examined the expression of IL-8 mRNA using Northern blot analysis and in situ mRNA hybridization (ISH) and protein production using enzyme-linked immunosorbent assay and immunohistochemistry in 8 human gastric carcinoma cell lines and 39 gastric carcinomas and corresponding normal mucosa (34 surgical specimens and 5 biopsy specimens). Of the 8 human gastric carcinoma cell lines, 6 expressed 1.8-kb IL-8 mRNA and secreted various levels of IL-8 protein. The expression of IL-8 by TMK-1 cells was induced by exposure to IL-1 alpha, epidermal growth factor, and transforming growth factor-alpha, shown previously to be autocrine growth stimulators for human gastric carcinoma cells. In tumor tissues, most of the tumors (28 of 34 surgical specimens and 4 of 5 biopsy specimens) expressed IL-8 at higher levels than the corresponding normal mucosa. ISH and immunohistochemical analyses revealed that IL-8 mRNA and protein were localized in the cytoplasm of tumor cells. The number of blood vessels in the gastric carcinomas was determined by using antibodies against CD34. The level of IL-8 mRNA in the neoplasms strongly correlated with vascularization (Spearman correlation, r = 0.812; P = 0.001). The data suggest that IL-8 produced by tumor cells may regulate neovascularization and, hence, the growth and spread of human gastric carcinoma.

Adult↗
PubMed1998

[Molecular diagnosis of gastrointestinal cancers].

Common and distinct genetic alterations are involved in the multistep mechanism of gastrointestinal carcinogenesis. Inactivation of the p53 and APC genes, activation of teleomerase and anomalous CD44 expression are common events that serve as a genetic marker for differential diagnosis of cancer. Amplification of cyclin D1 gene is preferentially found in esophageal cancer, whereas cyclin E gene amplification is frequently associated with both gastric and colorectal cancers. Multiple genetic alterations differ depending on the two histological types of gastric cancer. These genetic alterations can be applied in the multistep mechanism of the development and progression of gastrointestinal cancers. By application of these observations in clinical practice, we can facilitate and improve the differential diagnosis on cancer, obtain information on the grade of malignancy, determine patient prognosis, and identify patients at high risk for developing multiple cancers.

Adenomatous Polyposis Coli Protein↗
PubMed1998

[Application of antisense human telomerase RNA toward cancer therapy].

We overviewed recent results of anti-tumor effects and inhibition of telomerase activity in tumor cells through antisense human telomerase RNA(hTR). By introducing antisense hTR expression construct into tumor cells, reduction of telomeric DNAs and crisis or cellular senescence occurred in several human cancer cell lines. Antisense oligonucleotides to hTR synthesized with peptide nucleic acids and phosphorothioate deoxyribonucleic acids(PS) also inhibited telomerase activity in vitro. Furthermore, PS antisense hTR had significant effect to decrease tumor size and a number of metastatic nodules in a xenograft human cancer-nude mouse model. Taken together, the telomerase inhibitors targeting to hTR are expected to be novel anti-tumor agents.

Animals↗
PubMed1998

[Analysis of expression of human telomerase RNA in gastric precancerous and cancerous lesions by using in situ mRNA hybridization].

We described the localization of human telomerase RNA (hTR) expression in human gastric precancerous and cancerous lesions by using in situ mRNA hybridization. Diffusely high hTR expression was found in all carcinoma and adenoma tissues. Partially high hTR expression was seen in 75% hyperplastic polyps, 47% complete-type intestinal metaplasia and 21% incomplete-type intestinal metaplasia. All chronic gastritis without intestinal metaplasia possessed normal levels of hTR expression. The expression of hTR was heterogeneous and infiltrating lymphoid cells also expressed high levels of hTR expression. Taken together, overexpression of hTR due to stem cell hyperplasia is an early event of carcinogenesis of the stomach.

Adenoma↗
PubMed1998

nm23 expression in carcinoma of the uterine cervix.

To evaluate the significance of nm23 protein expression in cervical carcinoma, 83 patients with stage IB disease, treated primarily with surgery were studied immunohistochemically. Of the cases 57 were squamous carcinoma, 9 were adenocarcinoma, 14 were adenosquamous carcinoma and 3 were small-cell carcinoma. nm23 expression was positive in 63% of the cases. Although positive expression was more common in squamous and adenosquamous type tumors, negative expression was dominant in adenocarcinoma (P<0.05). When nm23 expression was compared with the clinicopathologic risk factors, there was no correlation of expression with the grade, deep invasion of the stroma, parametrial involvement and lymph node metastasis. But expression was inversely correlated with the number of metastatic lymph nodes (P<0.05). Although 3 or more lymph node metastases is a very poor prognostic sign, nm23 expression was not correlated either with recurrence or survival. Expression was negative in 77% of metastatic lymph nodes and in all of the recurrences. The predominance of negative expression in metastatic lymph nodes (P<0.05) and recurrences seems to be related to the aggressive behavior of the negative clone in the heterogeneous primary tumor.

Adult↗
PubMed1998

Abnormal expression of cripto and p53 protein in endometrial carcinoma and its precursor lesions.

Many oncogenes and tumor suppressor genes are involved in multistep carcinogenesis. Cripto is an epidermal growth factor (EGF) related gene which shares homology with EGF and TGFalpha. The aim of this study was to evaluate the role of abnormal p53 and cripto oncogene expression in endometrial carcinogenesis and progression using a hyperplasia carcinoma sequence model. Ninety-six primary endometrial adenocarcinomas and 30 hyperplastic tissues of which 7 were atypical (AH), were immunohistochemically examined for the presence of cripto and abnormal p53 protein. Immunopositivity was compared in hyperplastic and carcinoma tissues and analysed for conventional clinicopathological prognostic variables such as grade, depth of myometrial invasion, lymphovascular invasion, lymph node metastases and clinical stage. Cripto immunoreactivity was strong in most cases of AH, and endometrial carcinomas revealed 71% overall and 41% strong positivity, while hyperplasias without atypia were weakly stained. There was no correlation between cripto expression and clinicopathological prognosticators. Abnormal p53 was not observed in hyperplasias but AH and carcinomas expressed 14% and 25% overall positivity, respectively. There was a statistically significant correlation between the stage of the disease and abnormal p53 accumulation. Our results suggest that both cripto and p53 may play a role in endometrial carcinogenesis while abnormal p53 expression is an important parameter for disease progression.

Carcinoma↗
PubMed1998

Significance of vessel count and vascular endothelial growth factor in human esophageal carcinomas.

The purpose of this study was to determine the angiogenic profile of human esophageal carcinomas. The expression of vascular endothelial growth factor (VEGF) was examined in 6 esophageal carcinoma cell lines and 119 human esophageal carcinoma tissues by Northern blot analysis and immunohistochemistry, respectively. Immunohistochemistry using antibodies against CD34 (endothelial cell specific) was carried out on archival specimens, and microvessels were quantitated by counting vessels in a x200 field in the most vascular area of the tumor. All of the cell lines constitutively expressed VEGF mRNA at various levels. A total of 71 of 119 (59.7%) tumors showed intense VEGF immunoreactivity in the cytoplasm of cancer cells. Vessel count was significantly higher in the VEGF-positive tumors than it was in the VEGF-negative tumors. VEGF expression correlated with the depth of tumor invasion, tumor stage, venous invasion, and lymphatic invasion. The survival rate of patients with high vessel density in the tumor was significantly worse than that of patients with low vessel density in the tumor. There was a tendency for poorer prognosis in the group with VEGF-positive tumors compared with that of the group with VEGF-negative tumors. Overall, these results suggest that VEGF is associated with tumor progression by stimulating angiogenesis in human esophageal carcinoma.

Blotting, Northern↗
PubMed1998

[New molecular prognostic markers in gastric carcinoma].

Many molecular events have been reported as prognostic factors in gastric cancer. Amplifications of K-sam and c-met genes are often associated with poorly differentiated adenocarcinoma, while ERBB2 genes are amplified in well--differentiated adenocarcinomas of the stomach. Alterations of tumor suppressor regulators confer progression of gastric cancer. On the other hand, multi autocrine loops of growth factors/receptors in gastric cancer cells play a key role in the progression and metastasis of cancer cells. The overexpression of K-sam gene, occurs in 31.9% of gastric cancers, and the prognosis of patients with overexpression of K-sam gene is poorer than those without it. Multivariate analysis reveals that the overexpression of K-sam gene is an important factor for prognosis, lymphnode metastasis and the depth of tumor invasion of gastric carcinomas.

Female↗
PubMed1997

Telomerase activity in bladder carcinoma and its implication for noninvasive diagnosis by detection of exfoliated cancer cells in urine.

BACKGROUND: Telomerase is an enzyme that can reconstitute the ends (telomeres) of chromosomes after cell division and thus circumvent the cumulative damage that occurs in normal adult somatic cells during successive mitotic cycles. Recently, it has been proposed that this enzyme should, therefore, be detectable in immortal malignant cells but not in their normal counterparts, which stop dividing and senesce. Accordingly, telomerase activity has been reported in many types of malignant tumors, including those of the gastrointestinal tract, breast, and lung but little information was available regarding its status in bladder carcinoma or in exfoliated cancer cells. METHODS: In the current study, telomerase activity was examined by a polymerase chain reaction-based assay designated TRAP (telomeric repeat amplification protocol) in tissue samples from 56 bladder carcinomas, 17 nonneoplastic bladder lesions, and 2 dysplastic lesions of the urinary tract. The feasibility of identifying cancer patients by the detection of telomerase activity in exfoliated cancer cells in the urine was also investigated. Such activity was assayed in centrifuged urine cell pellets from 26 bladder carcinoma patients and from 83 patients with no evidence of malignant disease. RESULTS: Evidence of telomerase was detected in solid tissue specimens from 48 of the 56 bladder carcinomas (86%) regardless of tumor stage or differentiation, whereas it was not found in any normal bladder tissue specimen. However, it was present in the dysplastic bladder lesions as well as in nearly all Stage I well differentiated carcinomas, suggesting that its activation occurs for the early stages of carcinogenesis and could perhaps be a useful marker for the detection of early primary or recurrent bladder tumors. Telomerase activity was detected with various signal intensities in urine specimens from 16 of the 26 patients with bladder carcinoma (62% sensitivity), whereas only 3 of 83 nonmalignant urine samples showed any activity (96.4% specificity); this was very weak. CONCLUSIONS: These results suggest that telomerase could be a good diagnostic marker for the early noninvasive identification of patients with bladder carcinoma by facilitating the detection of exfoliated immortal cancer cells in their urine.

Aged↗
PubMed1997

Immunohistochemical studies on EGF family growth factors in normal and ulcerated human gastric mucosa.

Expression of members of the epidermal growth factor family, including epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), amphiregulin (AR), and Cripto, as well as their putative receptor, epidermal growth factor receptor (EGFR), was studied immunohistochemically in human gastric mucosa to evaluate their possible roles in cell proliferation of normal and regenerative gastric mucosa. We also examined the correlation betwen cell proliferation and EGFR by double immunohistochemical staining for proliferating cell nuclear antigen (PCNA) and EGFR. In normal gastric mucosa, TGF-alpha, Cripto, and AR immunoreactivities were observed in the surface epithelial and parietal cells of gastric fundic glands, respectively. EGF immunoreactivity was not observed in any of normal mucosa examined. EGFR immunoreactivity was detected on foveolar cells in proliferative zones and in parietal cells. Double immunostaining revealed that EGFR immunoreactivity was distributed much more widely than PCNA immunoreactivity. PCNA positive epithelial cells adjacent to gastric ulcer margin expressed relatively intense EGFR but did not express any of the growth factors examined. On the other hand, relatively intense immunoreactivity of both TGF-alpha and Cripto was detected in PCNA-negative regenerative epithelium located distant from gastric ulcer margin. Relative immunoreactivity of AR in regenerative gastric epithelium associated with ulcer was not different from that in normal gastric mucosa. TGF-alpha, AR, and Cripto are considered to play important roles in normal gastric mucosal proliferation, and TGF-alpha and Cripto may be involved in ulcer healing, possibly via a paracrine mechanism.

Amphiregulin↗