Biomedical subjects

E Tahara

Publications and source records attributed to E Tahara.

At least 109 records · Page 6Linked to original sources

PubMed1997

Detection of telomerase activity in exfoliated cancer cells in colonic luminal washings and its related clinical implications.

Telomerase is a ribonucleoprotein capable of replacing telomeric DNA sequences that are lost at each cell division. Under normal circumstances, it is active in rapidly dividing embryonic cells and in stem cell populations but not in terminally differentiated somatic cells. Much attention has recently focused on the hypothesis that activity of this enzyme is necessary for cells to become immortal. This predicts that telomerase activity should be detectable in malignant cells and tissues but not in their normal counterparts, which slowly senesce and die. In accordance with this notion, telomerase activity has been reported in a wide range of malignancies, including those of the gastrointestinal tract, breast and lung. In the present study, we used a polymerase chain reaction (PCR)-based assay for telomerase activity, designated the "telomeric repeat amplification protocol (TRAP)', to examine initially 35 colonic carcinomas, their corresponding normal tissues and 12 inflammatory bowel disease (IBD) lesions. We detected strong enzyme activity in 32 (92%) of the 35 colon carcinomas while there was no activity in 30 (86%) of 35 matched normal colonic tissue specimens and only very weak activity in the remainder. Four of seven specimens of ulcerative colitis and two of five Crohn's disease lesions were negative, and the rest were only weakly positive. These results led us to examine whether telomerase could be detected in carcinoma cells exfoliated into the colonic lumen. We assayed lysates of exfoliated cells in luminal washings from colectomy specimens of 15 patients with colon carcinoma and nine with IBD. Telomerase activity was detected in washings from 9 (60%) of the 15 colon carcinoma cases but not in any from cases with IBD, suggesting that it can be a good marker for the detection of colon carcinoma, possibly even in non-invasively obtained samples.

Aged↗

PubMed1997

Growth inhibition of cultured human gastric cancer cells by 9-cis-retinoic acid with induction of cdk inhibitor Waf1/Cip1/Sdi1/p21 protein.

The effect of 9-cis-retinoic acid (9-cis-RA) on the growth of eight gastric cancer cell lines was related to their transcription levels of mRNAs for retinoid receptors. Northern blot analysis showed that seven (TMK-1, MKN-1, -28, -45, -74, HSC-39, KATO-III) out of eight gastric cancer cell lines synthesized mRNAs for retinoic acid receptors (RARs) and retinoid X receptor-alpha (RXR-alpha). MKN-7 cells did not transcribe either RARs or RXR-alpha at the mRNA level although they appeared to have no alterations at the gene level. The growth of all of the cell lines except for MKN-7 cells was inhibited by 1 x 10(-6) M 9-cis-RA. Cell cycle distribution analysis revealed that G0-G1 arrest was not induced by exposure to 9-cis-RA in the sensitive TMK-1 and KATO-III cells or the resistant MKN-7 cells. Interestingly, 9-cis-RA temporarily increased the amount of the cyclin dependent kinase (cdk) inhibitor, Waf1/Cip1/Sdi1/p21 protein, and also reduced the amount of cdk-7, epidermal growth factor receptor (EGFR) and cyclin D1 proteins, followed by reduction in phosphorylation of the product of the retinoblastoma tumor suppressor gene (Rb) in the sensitive TMK-1 cells, but not in the resistant MKN-7 cells. These results suggest that 9-cis-RA has a cytostatic effect on gastric cancer cells that synthesize the receptor molecules through cell cycle regulatory machinery.

Adenocarcinoma↗

PubMed1997

Overexpression of cyclin-dependent kinase-activating CDC25B phosphatase in human gastric carcinomas.

CDC25 phosphatases activate cyclin-dependent kinases by removing inhibitory phosphate groups on the molecules and positively regulate the cell cycle progression. The expression of CDC25A, B and C was examined in gastric carcinoma cell lines and gastric carcinoma tissues by northern blotting and immunohistochemistry. The gastric carcinoma cell lines expressed CDC25A, B and C mRNA at various levels. The expression levels of CDC25B were generally higher than those of CDC25A and C. Of the 40 gastric carcinomas, 70% of the tumors expressed CDC25B mRNA at higher levels than the corresponding normal mucosas, while 38% overexpressed CDC25A mRNA. The CDC25C expression was at very low or undetectable levels. No obvious correlation was detected between the expression of CDC25B and p53 gene mutations. Immunohistochemically, CDC25-positive tumor cells were detected in 43 (78%) of 55 gastric carcinoma cases, of which 27 (49%) were strongly positive. Strong expression of CDC25B protein was associated with advanced stage and deep invasion. Furthermore, the incidence of strong expression was significantly higher in carcinomas with nodal metastasis than in those without metastasis. These findings suggest that overexpression of CDC25B may favor development and progression and may be an indicator of malignant behavior of gastric carcinomas.

Adenocarcinoma↗

PubMed1997

Expression of interleukin-6 and its effect on the cell growth of gastric carcinoma cell lines.

The expression and the effect of IL-6 were examined in human gastric carcinoma cell lines to determine whether IL-6 serves as a growth stimulator. The expression of IL-6 mRNA was detected in three (TMK-1, MKN-1, MKN-7) of 8 gastric carcinoma cell lines. All three cell lines secreted IL-6 into the culture fluid, in large amounts in the cases of MKN-1 and MKN-7 cells. Scatchard plot analysis of IL-6 binding revealed that MKN-1 and MKN-7 cells had both high- and low-affinity receptors. Cell growth of MKN-1 and MKN-7 cells was stimulated by IL-6, while anti-IL-6 antibody inhibited growth. The expression of IL-1 alpha mRNA by these three cell lines was induced by IL-6. IL-1 alpha increased the expression of mRNA for IL-6 by TMK-1 cells. These findings indicate that IL-6 induced by IL-1 alpha is an autocrine growth factor for some gastric carcinomas.

Adenocarcinoma↗

PubMed1997

Expression of human telomerase RNA is an early event of stomach carcinogenesis.

Expression of human telomerase RNA (hTR) and telomerase activity in gastric cancer and corresponding non-cancerous mucosa were studied. Telomerase activity was detected in 23 (88%) of 26 carcinoma tissues. Although all tumor specimens and non-cancerous mucosa expressed various levels of hTR, 21 (81%) of 26 cases expressed hTR at a higher level in the tumor than that in the corresponding mucosa. All 8 gastric carcinoma cell lines also expressed hTR at high levels. Nine (35%) of 26 non-cancerous mucosa showed telomerase activity and all of them contained intestinal metaplasia. The incidence of telomerase-positive mucosa in grade 2 intestinal metaplasia was significantly higher than that in grade 0 or grade 1 intestinal metaplasia, whereas hTR overexpression was found in grade 0 or grade 1 intestinal metaplasia as well as grade 2 intestinal metaplasia. The degree of Helicobacter pylori infection increased in parallel with the level of hTR expression and telomerase positivity. These results overall suggest that Helicobacter pylori infection may be a strong trigger for hTR overexpression in intestinal metaplasia, and this may lead to telomerase reactivation.

Adult↗

PubMed1997

Reduced expression of cyclin-dependent kinase inhibitor p27Kip1 is associated with advanced stage and invasiveness of gastric carcinomas.

Reduced expression of a cyclin-dependent kinase inhibitor p27Kip1 has recently been shown to predict poor survival of patients with breast and colorectal cancers. We studied the expression of p27Kip1 in gastric carcinomas by northern blotting, western blotting and immunohistochemistry to determine whether lack of p27 has implications for aggressiveness of gastric cancer. Reduced expression of p27 was detected in 40% of the gastric carcinomas at the mRNA level, while it was detected in 57% at the protein level. No gross alterations of the p27 gene were observed in any of the cases examined by Southern blot analysis. Immunohistochemical studies revealed that the expression of p27 was well preserved in most of the gastric adenomas, whereas it was so in only 26% of the gastric carcinomas. Fifty-six percent of the carcinomas showed almost no p27-positive cells. Decrease of p27-positive cells significantly correlated with advanced stage, depth of tumor invasion and lymph node metastasis. The expression of p27 showed an inverse correlation with the expression of cyclin E. These findings suggest that reduction of p27Kip1 protein may reflect the progression of gastric carcinomas and may be an indicator of high-grade malignancy.

Adenocarcinoma↗

PubMed1997

Expression of p21WAF1/CIP1 in colorectal adenomas and adenocarcinomas and its correlation with p53 protein expression.

The expression of p53-inducible cyclin-dependent kinase inhibitor, p21WAF1/CIP1 in non-neoplastic mucosa, adenoma and adenocarcinoma of the colorectum was examined by immunohistochemistry and western blotting and its relation with the expression of p53 protein was analyzed. Non-neoplastic epithelial cells at the surface area showing no proliferative activity expressed p21WAF1/CIP1. The expression of p21WAF1/CIP1 was immunohistochemically detected in 55% (206/377) of the adenomas and 66% (190/289) of the adenocarcinomas, respectively. The incidence of strongly positive cases was significantly higher in the adenocarcinomas (27%) than in the adenomas (18%) (P < 0.05). The incidence of cases with strong p21WAF1/CIP1 expression was higher in stages 0, 1 and 2 carcinomas than in stages 3 and 4 carcinomas (P < 0.05). A decrease in the incidence of cases with strong expression was detected in carcinomas invading deeper than muscularis propria. The incidence of strongly positive cases was significantly lower in carcinomas with lymph node metastasis than those without metastasis (P < 0.05). The expression of p21 as well as p53 detected by western blotting was compatible with the results of immunohistochemistry in most cases examined. However, there was no significant correlation between the expression of p21WAF1/CIP1 and the abnormal accumulation of p53. These findings overall suggest that: (i) the physiological expression of p21WAF1/CIP1 may be associated with cellular senescence of colorectal mucosa; (ii) reduced expression of p21WAF1/CIP1 may participate in the progression of colorectal carcinoma; and (iii) p53-independent pathway may be considerably involved in the induction of p21WAF1/CIP1.

Adenocarcinoma↗

PubMed1997

Altered microsatellites in incomplete-type intestinal metaplasia adjacent to primary gastric cancers.

AIM: To investigate the presence of genetic instability in precancerous lesions of the stomach. METHODS: Fifteen cases of sporadic gastric cancers with a background of intestinal metaplasia were studied by microsatellite assay at nine loci. Altered metaplastic mucosa was microdissected, reconstructed topographically, and examined immunohistochemically with an anti-p53 antibody, comparing its positive area with foci of microsatellite instability in each individual. RESULTS: Alterations at one or more loci were observed in seven of 15 cancers (46.7%) and four of 15 intestinal metaplasias (26.7%). Two cases of replication error positive phenotype had no microsatellite alterations in their metaplastic mucosa. All the microsatellite alterations in the metaplastic mucosa were restricted to incomplete-type intestinal metaplasia around the respective cancers. Moreover, in one case, an identical pattern of microsatellite alteration was detected in the cancer tissue and in the adjacent metaplastic mucosa, suggesting the sequential development of gastric cancer from intestinal metaplasia. Frequent alteration was found at the locus D1S191 (1q), indicating that this locus might be altered early in the development of intestinal-type gastric cancer. No significant association between microsatellite instability and p53 immunoreactivity was observed in the cases examined. CONCLUSION: These results indicate that microsatellite instability may be an early event in stomach carcinogenesis, especially in intestinal-type cancers.

Adenocarcinoma↗

PubMed1997

Growth inhibitory effect of interferon-beta is associated with the induction of cyclin-dependent kinase inhibitor p27Kip1 in a human gastric carcinoma cell line.

The effect of IFN-beta on cell growth and the mechanism of growth modulation was examined in human gastric carcinoma cell lines. IFN-beta inhibited the cell growth of TMK-1 cells, whereas it did not affect the growth of the other three cell lines (MKN-7, -28, and -45). The number of apoptotic cells in IFN-beta-treated TMK-1 cells was 2-fold the number of those in control TMK-1 cells, whereas the induction of apoptosis was not observed in IFN-beta-treated MKN-28 cells. IFN-beta enhanced the expression of cyclin-dependent kinase inhibitor p27Kip1 at mRNA and protein levels. The increased p27Kip1 bound preferentially to CDK6. The phosphorylation level of retinoblastoma protein in TMK-1 cells was reduced by IFN-beta treatment. IFN-beta did not affect the expression of cell cycle regulators in MKN-28 cells. These results suggest that the induction of p27Kip1 by IFN-beta might confer inhibition of cell growth, leading to subsequent apoptosis in TMK-1 cells.

Adenocarcinoma↗

PubMed1997

Action of thrombopoietin at the megakaryocyte progenitor level is critical for the subsequent proplatelet production.

Formation of proplatelets from megakaryocytes is believed to be the first step of platelet production in vitro. In this study, we evaluated the effects of recombinant human thrombopoietin (hTPO) on the development of proplatelets from a GpIIb/IIIa+ population of rat bone marrow cells highly enriched for late megakaryocyte progenitors (GpIIb/IIIa+ CFU-MK) that we recently found to be a primary target population of TPO. Quantitative measurement of hTPO-induced proplatelet formation was performed in liquid cultures. Proplatelet formation from megakaryocytes derived from GpIIb/IIIa+ CFU-MK in the presence of hTPO began on day 4 of culture and peaked the following day. On day 5 of culture, lower concentrations of hTPO expanded the number of megakaryocytes, increased the number of proplatelets and the percentage of proplatelet-developing megakaryocytes. Increasing hTPO concentrations resulted in a modest decrease in proplatelet development. We next used hTPO to derive immature or mature megakaryocytes from GpIIb/IIIa+ CFU-MK. These populations of cultured megakaryocytes spontaneously formed proplatelets when recultured in the absence of exogenous hTPO. The addition of hTPO at higher concentrations modestly augmented proplatelet production from immature megakaryocytes derived from 2-day liquid cultures. However, either murine interleukin-6 (IL-6) or human IL-11, but not rat IL-3, was more potent than hTPO in augmenting proplatelet formation from immature megakaryocytes. Each of these four cytokines had an inhibitory effect on proplatelet formation from more differentiated megakaryocytes derived from 3-day liquid cultures. These results indicate that TPO enhances proplatelet production primarily by stimulating CFU-MK to increase the number of proplatelet-forming megakaryocytes and that its action is clearly different from those of other cytokines that also stimulate megakaryocytopoiesis.

Animals↗

PubMed1997

Telomerase activity in premalignant and malignant lesions of human oral mucosa.

Recent studies have demonstrated a strong association between carcinogenesis and re-activation of telomerase in various human tumors. In the present study, we have analyzed the telomerase activity in 105 oral mucosal samples, including normal mucosa and premalignant and malignant lesions, by using the telomeric repeat amplification protocol assay. The telomerase activity was detected in normal oral squamous epithelium and in 75% of the oral leukoplakias and oral carcinomas. Although the telomerase activity was observed in normal and hyperplastic squamous epithelium, it showed some relationship with certain clinico-pathological factors in malignant lesions. Telomerase activity was found to have a relationship with the grade of tumor differentiation. Of 34 well-differentiated squamous cell carcinomas, only 10 (30%) exhibited high telomerase activity, whereas in moderately or poorly differentiated squamous cell carcinomas, all seven (100%) tumors displayed high activity. In addition, the level of telomerase activity had an inverse correlation with the treatment response in the early-stage tumors, and the activity differed significantly between the tumors in the following intraoral sites: nonkeratinizing mucosa (buccal mucosa, alveolus, and floor of mouth) and tongue. This preliminary result shows that telomerase activity is present in normal oral squamous epithelium, as it is in normal hematopoietic cells and in carcinomas, and that telomerase activity has a relationship with degree of tumor differentiation and treatment response. Thus, assessing the telomerase activity may be a useful prognostic marker in oral squamous cell carcinomas.

Biomarkers, Tumor↗

PubMed1997

[Stomach cancer].

Explore the source record for details and available documents.

Adenocarcinoma↗

PubMed1997

Identification of concurrent germ-line mutations in hMSH2 and/or hMLH1 in Japanese hereditary nonpolyposis colorectal cancer kindreds.

We analyzed microsatellite instability, alterations of the polyadenine tract in TGF-beta RII (transforming growth factor beta type II receptor gene), and mutations of hMSH2 and hMLH1 in 32 patients with familial colorectal cancer (29 kindreds) fulfilling the clinical criteria for hereditary nonpolyposis colorectal cancer (HNPCC), defined at the 34th Annual Meeting of Japanese Society for Cancer of the Colon and Rectum (Tokushima, Japan, 1991), including five kindreds fulfilling the Amsterdam criteria. Eighteen of 32 (56%) cases were replication error positive (RER+) at two or more microsatellite loci analyzed. The clinicopathological characteristics of RER+ cases corresponded well with those reported previously. Eleven of 18 RER+ cases showed RER+ at most of the microsatellite loci examined. Among these 11 cases (10 kindreds), 3 kindreds fulfilled the Amsterdam criteria and 7 kindreds did not. For these 10 kindreds, germ-line mutations in hMSH2 and hMLH1 were detected for 6 kindreds by PCR-SSCP analysis and direct sequencing. Only two of these six fulfilled the Amsterdam criteria; more than one germ-line mutation was detected in hMSH2 and/or hMLH1. Specifically, two point mutations of hMSH2 were detected in two kindreds, one point mutation of both hMSH2 and hMLH1 was detected in one kindred, two point mutations of hMSH2 and one point mutation of hMLH1 were detected in one kindred, and two point mutations of hMLH1 and one point mutation of hMSH2 were detected in one kindred. In addition, 19 of 26 (74%) cancer lesions of these 11 cases with the RER phenotype showed alterations of the polyadenine tract in TGF-beta RII. From our data, although seven kindreds did not fulfill the Amsterdam criteria, we considered them as HNPCC. Therefore, we suggest that the "Japanese criteria" have the advantage of being able to detect more HNPCC kindreds from borderline HNPCC kindreds.

Adaptor Proteins, Signal Transducing↗

PubMed1997

[An overview of research on p53 tumor suppressor gene].

The concept of tumor suppressor gene introduced in the last decade has provided an enormous understanding of the mechanism of human carcinogenesis with the intensive study of p53 during the 1990's. The product of p53 tumor suppressor gene is a transcription factor which recognizes and binds to a specific DNA consensus sequence existing in the promoter region of p53 responsive genes. The main physiological functions of p53 are (1) cell cycle regulation mainly at the G1 check point, (2) induction of apoptosis, and (3) stabilization of genome. As each of them are indispensable gatekeeping devices of the cell for the suppression of malignant transformation, the alteration of p53 gene, which is found more than half of human malignancies, may play a central role in multistep carcinogenesis.

Apoptosis↗

PubMed1997

[Telomere and telomerase associated genes].

Telomerase is a ribonucleoprotein, telomere specific reverse transcriptase, which contains some protein components and telomerase RNA components. Human telomerase RNA and some telomerase components have been identified but not completely. More recently, human telomerase catarytic subunits have been cloned, which are called hTRT or hEST2. The expression of hTRT in human cultured cells is well correlated with telomerase activity and immortality. Moreover, the expression of hTRT in cancer tissues is higher than that of normal tissues. These results suggested that hTRT and telomerase activity may be a powerful additional tool for cancer diagnosis.

DNA-Binding Proteins↗

PubMed1996

Telomerase activity in human breast cancer and benign breast lesions: diagnostic applications in clinical specimens, including fine needle aspirates.

We analysed telomerase activity in normal, benign and malignant breast tissues and in fine needle aspirates by a PCR-based assay. The tissue samples we used in this assay consisted of 20 cryostat sections, 10 microns thick, from each breast biopsy. This method was used to obtain effective extraction from small samples and to confirm the histological identity of the specimen by microscopical examination of serial sections. Fifty-two of 71 breast carcinomas were positive for telomerase activity, and the intensity of this was strong in most cases, whereas all 6 samples of normal breast tissue and 17 of fibrocystic disease were negative and only 1 of 15 fibroadenomas was positive. Invasive ductal carcinomas were more frequently positive than invasive lobular carcinomas. There was no correlation of telomerase activity with tumour size or the occurrence of lymph node metastasis. Evaluation of our assay system showed that a signal of telomerase activity was detectable in extracts from single cryostat sections (< 1 mm2) of a cancer specimen and from as few as 4 cells of a human breast cancer cell line. On the basis of the above data, we applied this assay to fine needle aspirates of breast lesions. Ten of 15 aspirates which had been cytopathologically diagnosed as cancer were strongly positive, while 26 of 29 benign aspirates were totally negative and the remaining 3 showed only borderline activity. In 3 cases, the telomerase result could have helped establish a diagnosis when the cytological observations were inconclusive. Our results indicate that this sensitive assay could become a useful new modality for supplementing microscopic cytopathology in the detection of cancer cells in small tissue biopsies and fine needle aspirates.

Autoradiography↗

PubMed1996

Microsatellite instability in precancerous lesions and adenocarcinomas of the stomach.

BACKGROUND: It is generally known that replication errors (RERs) at microsatellite loci detected in human malignancies reflect a genetic instability that is caused by abnormalities of DNA mismatch repair system and underlie human carcinogenesis. The authors analyzed RERs in precancerous lesions and adenocarcinomas of the stomach to learn when genetic instability occurs in stomach carcinogenesis. In addition, the authors examined genetic instability occurs in stomach carcinogenesis. In addition, the authors examined genetic alterations of the p53 and adenomatous polyposis coli (APC) genes to investigate the correlation between genetic instability and genetic alterations in these tumor suppressor genes. METHODS: The authors examined microsatellite assay at 9 microsatellite loci in 24 sporadic gastric cancers, 12 gastric adenomas, and 9 intestinal metaplasia mucosae of the stomach from patients with gastric cancers using fresh frozen or formalin fixed and paraffin embedded samples paired with normal mucosae. They also screened loss of heterozygosity (LOH) of the p53 and APC genes by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. RESULTS: In total, the RER(+) phenotypes were observed in 8 of 24 (33%) gastric cancers, 5 of 12 (42%) gastric adenomas, and 3 of 9 (33%) intestinal metaplasia mucosae of the stomach. Histology, RERs were detected in 3 of 9 (33%) well differentiated adenocarcinomas, 2 of 11 (18%) poorly differentiated adenocarcinomas, and 3 of 4 (75%) scirrhous type gastric cancers respectively. Several cases showed RERs at many microsatellite loci simultaneously. Some RER(+) phenotypes had genetic alterations of the p53 or APC genes detected by LOH using PCR-RFLP analysis. However, no significant correlation was found between RER(+) phenotypes and LOH in these genes. CONCLUSIONS: The frequency of RERs in detected gastric cancers were almost the same when compared with previously reported data. Interestingly, RERs were detected in greater than 30% of precancerous lesions, suggesting that genetic instability is an early somatic event of multistep stomach carcinogenesis. It also suggests that the adenoma-carcinoma sequence does exist in stomach carcinogenesis, especially in well differentiated adenocarcinomas. Moreover, alterations in the p53 and APC genes detected by PCR-RFLP analysis did not correlate with RER(+) phenotypes.

Adenocarcinoma↗

PubMed1996

Evaluation of CD44 transcription variants in human digestive tract carcinomas and normal tissues.

We generated DNA probes for CD44 variable region exons 11 (v6) to 14 (v9) and also for intronic sequences and examined the expression of aberrant CD44 transcripts in digestive tract carcinomas, colorectal adenomas and intestinal metaplasia of the stomach. The study used the reverse transcription-polymerase chain reaction/Southern blot technique. Among the probes generated, the CD44 intron 9 probe was the best for distinguishing cancer tissue from normal tissue in adenocarcinomas of the colorectum or stomach. All the colorectal adenocarcinomas revealed overexpression of CD44 variants containing the intron 9 sequence compared with the corresponding normal colorectal mucosa. The overexpression of such abnormal CD44 variants was observed from an early stage in colorectal cancer and did not correlate with nodal or distant metastatic status. In intestinal metaplasia of the stomach, aberrant CD44 transcripts with characteristic 2 or 3 peaks containing intron 9 were observed. On the other hand, in oral and esophageal squamous cell carcinomas and corresponding normal squamous epithelia, overexpression of CD44 variants with variable exons and retained intron 9 sequence was frequently observed in both cancer tissue and corresponding normal mucosa. Examination of the expression of CD44 variants in a screening panel of normal tissues from the whole body revealed that overexpression of transcripts containing exon 11 and 14 as well as of the intron 9 sequence was constantly observed in tissues with squamous epithelia like skin, oral mucosa, esophagus and uterine cervix. Expression of these variants was also found in urinary bladder, respiratory tract, pancreas and salivary glands. Our results overall indicate that detecting the overexpression of abnormal CD44 transcripts, especially ones containing the intron 9 sequence, could be a powerful indicator for the presence of adenocarcinomas in the digestive tract. However, it is not applicable for the diagnosis of malignancies originating from squamous epithelia.

Adenoma↗