Jpn J Cancer Res
· 2002 Jun · PMID 12079508
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Although some benign breast lesions such as multiple intraductal papilloma have been pointed out as a risk factor for breast cancer, there is little documentation about trends in the incidence of benign tumors of the bre...Although some benign breast lesions such as multiple intraductal papilloma have been pointed out as a risk factor for breast cancer, there is little documentation about trends in the incidence of benign tumors of the breast in Japanese women. The author conducted an epidemiological study using data abstracted from the Hiroshima Tumor Tissue Registry file, which includes cases of malignant and benign neoplasms in Hiroshima prefecture between 1973 and 1995. A total of 17064 cases of female breast tumor were registered in the file between 1973 and 1995. The registration rate for fibroadenoma of the female breast was 19.5 among females and peaked during the 5-year period 1983 - 1987, while the fibroadenoma registration rate in Hiroshima gradually decreased between 1988 and 1995. The registration rate for intraductal papilloma has risen substantially in Hiroshima, with about a 5-fold increase among females between 1973 and 1995. The mean proportion of fibroadenoma cases accompanied by malignant tumors of the breast was 1.85%, and there was no significant change in the mean proportion between 1973 and 1995 (P = 0.17). On the other hand, the mean proportion of intraductal papilloma cases accompanied by malignant tumors of the breast gradually rose with about a 14-fold increase among females between 1973 and 1995. The significance of intraductal papilloma as a risk factor for breast cancer may have increased.
Fukuhara H, Kuramochi M, Fukami T
… +10 more, Kasahara K, Furuhata M, Nobukuni T, Maruyama T, Isogai K, Sekiya T, Shuin T, Kitamura T, Reeves RH, Murakami Y
Jpn J Cancer Res
· 2002 Jun · PMID 12079507
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We recently identified TSLC1, a tumor suppressor gene in human lung cancer. Gene silencing by promoter methylation has been observed frequently in adenocarcinoma of the lung, liver, and pancreas. Here, we demonstrate tha...We recently identified TSLC1, a tumor suppressor gene in human lung cancer. Gene silencing by promoter methylation has been observed frequently in adenocarcinoma of the lung, liver, and pancreas. Here, we demonstrate that TSLC1 expression is also absent or markedly reduced in 3 of 4 prostate cancer cell lines. Promoter sequences of TSLC1 were heavily methylated in PPC-1 cells that lacked TSLC1 expression, supporting the idea that promoter methylation is strongly correlated with complete loss of gene expression. Promoter sequences of TSLC1 were also methylated significantly in 7 of 22 (32%) primary prostate cancers. Hypermethylation of the promoter occurred not only in advanced tumors, but also in relatively early-stage tumors. Restoration of TSLC1 expression substantially suppressed tumor formation of PPC-1 cells in nude mice. These findings indicate that alteration of TSLC1 is involved in prostate cancer.
Ugai H, Watanabe S, Suzuki E
… +3 more, Tsutsui-Nakata H, Yokoyama KK, Murata T
Jpn J Cancer Res
· 2002 May · PMID 12036457
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Recombinant viral vectors have been developed for use as therapeutic agents and for the introduction of exogenous genes into living cells. However, little is known about the viability and stability of such recombinant vi...Recombinant viral vectors have been developed for use as therapeutic agents and for the introduction of exogenous genes into living cells. However, little is known about the viability and stability of such recombinant viruses during storage, transport and delivery under various conditions. We describe here an analysis of the stability of an adenoviral vector in crude solutions of cell lysates during freezing and thawing and during storage at various temperatures in the presence and in the absence of glycerol. For example, the titer of adenoviruses in crude lysates of infected cells was reduced only ten-fold or three-fold after two hundred rounds of freezing and thawing or after incubation at 28 degrees C for 14 days, respectively. Our observations indicate that recombinant adenoviral vector was more stable than expected both during freezing and thawing and during storage at low temperatures. Our results confirm the importance of appropriate conditions for the delivery and transport of recombinant adenoviral vectors.
Ando M, Ando Y, Sekido Y
… +3 more, Ando M, Shimokata K, Hasegawa Y
Jpn J Cancer Res
· 2002 May · PMID 12036456
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Irinotecan often causes unpredictably severe, occasionally fatal, toxicity involving leukopenia or diarrhea. It is converted by carboxyesterase to an active metabolite, SN-38, which is further conjugated and detoxified t...Irinotecan often causes unpredictably severe, occasionally fatal, toxicity involving leukopenia or diarrhea. It is converted by carboxyesterase to an active metabolite, SN-38, which is further conjugated and detoxified to SN-38-glucuronide by UDP-glucuronosyltransferase (UGT). We genotyped the UGT1A7 gene by direct sequencing analysis and polymerase chain reaction-restriction fragment length polymorphism in 118 cancer patients and 108 healthy subjects. All the patients had received irinotecan-containing chemotherapy and were evaluated to see whether the variant UGT1A7 genotype would increase the likelihood of severe toxicity of irinotecan consisting of grade 4 leukopenia and/or grade 3 or more diarrhea. Among the 26 patients with severe toxicity, the allele frequencies were 61.5% for UGT1A7 (*)1, 15.4% for UGT1A7 (*)2, and 23.1% for UGT1A7 (*)3. On the other hand, the frequencies were 63.6% for UGT1A7 (*)1, 15.8% for UGT1A7 (*)2, and 20.7% for UGT1A7 (*)3 among the 92 patients without severe toxicity. None of the 118 patients had UGT1A7 (*)4. Neither univariate analysis (odds ratio, 1.13; 95% confidential interval, 0.46 - 2.75) nor multivariate logistic regression analysis (odds ratio, 0.74; 95% confidential interval, 0.26 - 2.07) found any significant association between carrying at least one of the variant alleles and the occurrence of severe toxicity. The distribution of UGT1A7 genotypes in 108 healthy subjects was not significantly different from that in the patients (P = 0.99 and 0.86 for those with and without severe toxicity, respectively), but significantly less than that in Caucasians reported previously (P < 0.001). The results suggested that determination of UGT1A7 genotypes would not be useful for predicting severe toxicity of irinotecan.
Inoue H, Takemura H, Kawai Y
… +3 more, Yoshida A, Ueda T, Miyashita T
Jpn J Cancer Res
· 2002 May · PMID 12036455
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Glucocorticoids remain among the most important drugs in the treatment of acute lymphoblastic leukemia (ALL). Although the mechanisms of glucocorticoid resistance have been studied in some T-cell leukemic cell lines, les...Glucocorticoids remain among the most important drugs in the treatment of acute lymphoblastic leukemia (ALL). Although the mechanisms of glucocorticoid resistance have been studied in some T-cell leukemic cell lines, less work has been done with B-cell lines. We established a dexamethasone (DEX)-resistant human pre-B lineage leukemia cell line (697/DEX) and investigated the mechanism of resistance. 697/DEX was over 430-fold more resistant to DEX compared with the parental cells (697/Neo). Overexpression of Bcl-2 protein was not observed in 697/DEX, different from the mechanism of resistance in Bcl-2-virus-infected cells (697/Bcl-2). Although the expression of p-glycoprotein (Pgp) in 697/DEX was positive, its functional activity was not detected. The numbers of glucocorticoid receptors (GR) in 697/DEX and 697/Bcl-2 were significantly lower than those in 697/Neo. In addition, 697/DEX and 697/Bcl-2 had higher levels of glutathione (GSH) than 697/Neo. In the presence of L-buthionine-(S, R)-sulfoximine (BSO), an inhibitor of GSH synthesis, both 697/DEX and 697/Bcl-2 recovered their sensitivity to DEX. Interestingly, cell death by the depletion of GSH did not involve caspase-3/7 activation in 697/Bcl-2 and 697/DEX, different from 697/Neo, suggesting a death mechanism through caspase-independent programmed cell death or necrosis. In conclusion, DEX-resistance in 697/DEX was related not only to a GR decrease, but also to an increase in intracellular GSH level in the DEX-resistant B-cell leukemia cell line. Circumvention of DEX-resistance with BSO may offer an approach to overcoming resistance to chemotherapy in B-cell lineage ALL.
Jpn J Cancer Res
· 2002 May · PMID 12036454
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The oncogenenic transmembrane tyrosine kinase receptor HER-2/neu is a promising target for treatment of HER-2-overexpressing cancers. The humanized anti-HER-2/neu antibody Trastuzumab is under clinical evaluation in comb...The oncogenenic transmembrane tyrosine kinase receptor HER-2/neu is a promising target for treatment of HER-2-overexpressing cancers. The humanized anti-HER-2/neu antibody Trastuzumab is under clinical evaluation in combination with chemotherapy against breast cancer. The combination of Trastuzumab and cisplatin is expected to be active against HER-2 / neu-expressing tumors. We examined the mechanisms of this combination effect against human solid tumor cells in the presence of human peripheral blood mononuclear cells (PBMCs) using an in vitro MTT assay. The growth-inhibitory effects of cisplatin (CDDP) on the tumor cells were not significantly affected by Trastuzumab in the absence of effector cells. CDDP alone at a dose of less than 12.5 mM did not affect the viability of PBMCs, as determined by MTT assay, suggesting that PBMCs could exert antibody-dependent cell-mediated cytotoxicity (ADCC) at this CDDP concentration. The combination of Trastuzumab and CDDP showed higher cytotoxic effects against the tumor cells in the presence of PBMCs. The CDDP concentration required to inhibit tumor cell growth by 50% was reduced to approximately 20% by Trastuzumab in the presence of PBMCs at an effector/target ratio of 10. It may be important to select combined chemotherapeutic agents which do not diminish the ADCC activity of Trastuzumab via PBMCs. Both the expression of HER-2 / neu and the ADCC activity may be important determinants of the therapeutic benefit of the Trastuzumab/CDDP combination.
Jpn J Cancer Res
· 2002 May · PMID 12036453
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Alkylating agents or platinum analogues initiate several excision repair mechanisms, which involve incision of the DNA strand, excision of the damaged nucleotide, gap filling by DNA resynthesis, and rejoining by ligation...Alkylating agents or platinum analogues initiate several excision repair mechanisms, which involve incision of the DNA strand, excision of the damaged nucleotide, gap filling by DNA resynthesis, and rejoining by ligation. The previous study described that nucleotide excision repair permitted incorporation of fludarabine nucleoside (F-ara-A) into the repair patch, thereby inhibiting the DNA resynthesis. In the present study, to clarify the repair kinetics in view of the inhibition by F-ara-A, normal lymphocytes were stimulated to undergo nucleotide excision repair by ultraviolet C (UV) irradiation in the presence or absence of F-ara-A. The repair kinetics were determined as DNA single strand breaks resulting from the incision and the rejoining using the alkaline single cell gel electrophoresis (comet) assay. DNA resynthesis was evaluated in terms of the uptake of tritiated thymidine into DNA. The lymphocytes initiated the incision step maximally at 1 h, and completed the rejoining process within 4 h after UV exposure. UV also initiated thymidine uptake, which increased time-dependently and reached a plateau at 4 h. A 2-h pre-incubation with F-ara-A inhibited the repair in a concentration-dependent manner, with the maximal inhibition by 5 mM. This inhibitory effect was demonstrated by the reduction of the thymidine uptake and by the inhibition of the rejoining. A DNA polymerase inhibitor, aphidicolin, and a ribonucleotide reductase inhibitor, hydroxyurea, were not so inhibitory to the repair process as F-ara-A at equimolar concentrations. The present findings suggest that inhibition of nucleotide excision repair may represent a novel therapeutic strategy against cancer, especially in the context of resistant cells with an increased repair capacity.
Serrano MJ, Sánchez-Rovira P, Algarra I
… +3 more, Jaén A, Lozano A, Gaforio JJ
Jpn J Cancer Res
· 2002 May · PMID 12036452
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Combination chemotherapy with gemcitabine (Gem), doxorubicin (Dox), and paclitaxel (Pac) (GAT) has been considered attractive as first-line treatment in metastatic breast cancer. We compared the potential of various sche...Combination chemotherapy with gemcitabine (Gem), doxorubicin (Dox), and paclitaxel (Pac) (GAT) has been considered attractive as first-line treatment in metastatic breast cancer. We compared the potential of various schedules of GAT to induce apoptosis on MDA-MB-231, MCF7, and T47D human breast cancer cell lines. The extent of apoptotic induction was analyzed by flow cytometry with 7-aminoactinomycin D (7AAD) staining. Differences between various schedules in terms of apoptotic induction were statistically significant (P < 0.05). The most effective apoptotic induction regimen was achieved by the sequence: Dox for 16 h followed by Pac + Gem. Schedules employing a 16-h interval between drug administrations induced higher levels of apoptosis in human breast cancer cell lines compared with schedules using a 4-h interval. The therapeutic efficacy of the experimental results shown in this paper has been clinically corroborated in a phase II trial in metastatic breast cancer patients.
Ohara M, Kawashima Y, Katoh O
… +1 more, Watanabe H
Jpn J Cancer Res
· 2002 May · PMID 12036451
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Although a number of studies have been carried out to examine the biological effects of radiation and ultraviolet radiation (UV), little is known concerning the effects of visible light. In the present study, exposure of...Although a number of studies have been carried out to examine the biological effects of radiation and ultraviolet radiation (UV), little is known concerning the effects of visible light. In the present study, exposure of B16 melanoma cells to blue light (wavelength 470 nm, irradiance 5.7 mW / cm(2)) from a light-emitting diode (LED) inhibited cell growth in proportion to the period of exposure, with no increase observed in the number of dead cells. The number of B16 melanoma colonies that formed after exposure to blue light for 20 min was only slightly less than that in non-exposed controls, but the colony size as assessed by the area covered by colonies and cell counts per colony were markedly decreased. The percentages of G0 / G1 and G2 / M phase cells were markedly increased, with a reduction in S phase cells as determined by flow cytometry after exposure to blue light. Furthermore, analysis of the incorporation of 5-bromo-2'-deoxyuridine (BrdU) into DNA also showed a reduction in the percentage of S phase cells after exposure. These results indicate that blue light exerts cytostatic effects, but not a cytocidal action, on B16 melanoma cells.
Shigemasa K, Katoh O, Shiroyama Y
… +4 more, Mihara S, Mukai K, Nagai N, Ohama K
Jpn J Cancer Res
· 2002 May · PMID 12036450
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To investigate the potential role of the BCL-2 gene family (BAX, BCL-2, MCL-1, and BCL-XL) in ovarian cancer development and progression, mRNA expression levels of these genes were measured using semi-quantitative PCR in...To investigate the potential role of the BCL-2 gene family (BAX, BCL-2, MCL-1, and BCL-XL) in ovarian cancer development and progression, mRNA expression levels of these genes were measured using semi-quantitative PCR in epithelial ovarian tumor tissues and normal ovaries. The immunohistochemical expression of MCL-1 in ovarian tumors was also examined. The expression levels of BAX and MCL-1 mRNA were significantly higher in ovarian cancers and in adenomas than in normal ovaries (P < 0.05). In contrast, the BCL-2 mRNA expression level in ovarian cancers was significantly lower than in ovarian adenomas and in normal ovaries (P < 0.05). Expression of BCL-XL mRNA was no different between normal ovaries and ovarian tumors. Log-rank testing showed that low BAX mRNA expression and high MCL-1 mRNA expression significantly correlate with poor survival for patients with stage III ovarian carcinomas (BAX, P = 0.05; MCL-1, P = 0.02). Immunohistochemical analysis showed that diffuse-positive expression of MCL-1 protein in mucinous carcinomas was significantly higher than in mucinous low malignant potential (LMP) tumors (P = 0.03). In ovarian cancer cases, diffuse-positive expression of MCL-1 protein significantly correlates with advanced clinical stage, high histologic grade, and poor survival (stage, P < 0.01; grade, P = 0.01; survival, P = 0.01). These results suggest that increased MCL-1 expression may play an important role in replacing the functions of increased BAX and decreased BCL-2 in ovarian carcinoma cells, thereby promoting cell survival, and resulting in a poor prognosis for patients with ovarian cancer.
Osanai M, Chiba H, Kojima T
… +5 more, Fujibe M, Kuwahara K, Kimura H, Satoh M, Sawada N
Jpn J Cancer Res
· 2002 May · PMID 12036449
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Endothelial Fas ligand (FasL) contributes to the "immune privilege" of tissues such as testis and eye, in which apoptosis is induced in infiltrating Fas-positive activated T cells and results in the inhibition of leukocy...Endothelial Fas ligand (FasL) contributes to the "immune privilege" of tissues such as testis and eye, in which apoptosis is induced in infiltrating Fas-positive activated T cells and results in the inhibition of leukocyte extravasation. In this study, we examined the role of endothelial FasL in controlling cancer cell transmigration using rat lung endothelial (RLE) cell line bearing a doxycycline-inducible hepatocyte nuclear factor (HNF)-4alpha expression system. We showed that a detectable level of FasL was expressed in RLE cells and that this expression was markedly up-regulated and well correlated to the degree of HNF-4alpha expression in a time-dependent manner. When various cancer cells were overlaid on an RLE monolayer sheet, we examined the ability of endothelial FasL to induce massive apoptosis in Fas-expressing cancer cells and found a causal link to inhibition of the transmigration. Finally, we showed that FasL was expressed in capillaries of the rat brain by immunohistochemical staining, suggesting that FasL serves its functions not only in vitro, but also in vivo. These results raise the possibility that HNF-4alpha is involved in regulating cancer cell transmigration by modulating the Fas-FasL system.
Kageyama S, Yoshiki T, Isono T
… +4 more, Tanaka T, Kim CJ, Yuasa T, Okada Y
Jpn J Cancer Res
· 2002 May · PMID 12036448
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Uroplakins (UPs) Ia, Ib, II, and III are tissue-specific and differentiation-dependent transmembrane proteins of the urothelium. We assessed the usefulness of human UP Ia as a histological marker by examining its express...Uroplakins (UPs) Ia, Ib, II, and III are tissue-specific and differentiation-dependent transmembrane proteins of the urothelium. We assessed the usefulness of human UP Ia as a histological marker by examining its expression in urinary bladder transitional cell carcinoma (TCC). A polyclonal antibody against human UP Ia was raised using a synthesized polypeptide. We applied our antibody to various organ tissues, including urothelium, and observed no crossreactivity. Analysis by RT-PCR of normal urothelium, TCC and other organ tissues indicated that the human UP Ia gene expression is highly specialized to urothelium, and is conserved in TCC. Using immunohistochemistry, we investigated the expression of UP Ia in TCC from patients who had undergone radical cystectomy and from autopsy cases. Positive staining (10% or more positive cancer cells) was noted in primary lesions from 61 of 63 (96.8%) cystectomy patients. Depending on pathological grade, high expression (50% or more positive cancer cells) was observed in 17 of 18 (94.4%) moderately- to well-differentiated TCC and in 36 of 45 (80.0%) poorly differentiated TCC. With regard to tumor invasion, high expression was noted in 20 of 22 (90.9%) superficial and 33 of 41 (80.5%) muscle-invasive TCC. Cause-specific survival rates were 68.6% and 75.0% in high- and low-expression patients, respectively (log-rank test, P = 0.855, mean follow-up; 65.0 months). In metastases, positive reactions were observed in 13 of 18 (72.2%) lesions. UP Ia may represent a specific histological marker judging from the stable expression, although its value as a prognostic factor remains undetermined.
Zheng K, Nagai Y, Kishimoto T
… +6 more, Yamazawa K, Tate S, Nemori R, Hirai Y, Sekiya S, Ishikura H
Jpn J Cancer Res
· 2002 May · PMID 12036447
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Collagen matrix degradation by malignant tumor cells plays an essential role in the process of tumor invasion and metastasis. The purpose of this study was to detect in situ gelatinase activity in endometrioid adenocarci...Collagen matrix degradation by malignant tumor cells plays an essential role in the process of tumor invasion and metastasis. The purpose of this study was to detect in situ gelatinase activity in endometrioid adenocarcinomas of the uterine corpus. In order to carry out quantitative evaluation, autoexposure time (AET) on gelatin-coated film (film in situ zymography: FIZ) was measured. The gelatinase activity was located primarily within cancers and was prominently suppressed by the addition of a chelating agent to the film. This suggests that matrix metalloproteinases (MMPs) play an important role in the gelatinase activity. The gelatinase activity in the normal endometrium is almost negligible, despite positive immunoreactivity for MMP-2 and -9. Tumor tissues that had invaded more than half of the myometrium showed significantly higher activity than those that had invaded less than half. There was no significant difference in gelatinase activity among tumor stages, grades, vessel invasion or immunoreactivity for MMPs, with the exception that stage 2b cancers showed higher activity than stage 1a. The study suggested that the level of MMP-mediated gelatinolysis is an important factor for myometrial invasion in uterine endometrioid adenocarcinoma. Thus, a quantitative assessment of active gelatinolysis using FIZ and AET should be a useful tool in evaluating in situ matriolytic activity in local myometrial invasion by uterine endometrioid adenocarcinoma.
Seko A, Nagata K, Yonezawa S
… +1 more, Yamashita K
Jpn J Cancer Res
· 2002 May · PMID 12036446
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Expression levels of sulfomucin in human colonic adenocarcinomas are lower than those in normal colonic mucosa; this should be in part caused by down-regulation of expression of sulfotransferases, but it remains unclear...Expression levels of sulfomucin in human colonic adenocarcinomas are lower than those in normal colonic mucosa; this should be in part caused by down-regulation of expression of sulfotransferases, but it remains unclear which Gal 3-O-sulfotransferase (Gal3ST) is responsible for the biosynthesis of sulfomucin. In this study, we first examined the substrate specificities of four Gal3STs cloned so far, and found that Galbeta1 3GlcNAcbeta1 3Galbeta1 4Glc (LNT) can be utilized only by Gal3ST-2 as an acceptor substrate. The substrate specificity of Gal3ST-2 is closely similar to those of Gal3ST activities present in human normal mucosa and adenocarcinomas, suggesting that Gal3ST-2 is the dominant Gal3ST in colon and colonic cancer. Secondly, using LNT as a substrate, we comparatively analyzed levels of Gal3ST-2 activities in non-mucinous adenocarcinoma, mucinous adenocarcinomas, and the adjacent normal mucosa. We found that levels of Gal3ST-2 activities in non-mucinous adenocarcinoma are significantly lower than those in the adjacent normal mucosa, while those in mucinous adenocarcinomas are not significantly different from those in the adjacent normal mucosa. Moreover, we showed by a competitive RT-PCR method that expression levels of transcript for Gal3ST-2 in non-mucinous adenocarcinoma are lower than those in normal mucosa. These results suggest that Gal3ST-2 is one of the enzymes responsible for biosynthesis of sulfomucin, and that expression levels of Gal3ST-2 are down-regulated in non-mucinous adenocarcinoma.
Okochi E, Ichimura S, Sugimura T
… +1 more, Ushijima T
Jpn J Cancer Res
· 2002 May · PMID 12036445
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Single nucleotide instability (SNI), an increase in spontaneous point mutation rates (MRs) without involvement of microsatellite instability, is present in rat mammary carcinoma cell lines and human breast cancer cell li...Single nucleotide instability (SNI), an increase in spontaneous point mutation rates (MRs) without involvement of microsatellite instability, is present in rat mammary carcinoma cell lines and human breast cancer cell lines. A:T to C:G transversions, which are generally rare, were frequently observed in two rat mammary carcinoma cell lines and in their primary carcinomas, and were considered to be related to the molecular mechanism of SNI. In this study, two known molecular mechanisms that cause increases of A:T to C:G transversions, inactivation of the MutT mammalian homologue (Mth1) gene and overexpression of the DNA polymerase k (Pol k) gene, were analyzed in two rat mammary carcinoma cell lines and 11 rat primary carcinomas. PCR-SSCP analysis revealed no mutations in the entire Mth1 coding region. Quantitative real-time RT-PCR analysis showed that Mth1 mRNA expression was slightly, but significantly, increased in the primary carcinomas (P = 0.001 using GAPDH for normalization, and P = 0.002 using histone H4, t-test), contrary to our expectation, and was decreased to 1 / 2 in the cell lines. The expression of Pol k, which is known to be error-prone with frequent A:T to C:G transversions, was rather decreased in the cell lines and primary carcinomas. Inactivation of Mth1 and overexpression of Pol k were unlikely to have caused SNI in the two rat mammary carcinoma cell lines with a high frequency of A:T to C:G transversions, and searching for other unknown molecular mechanisms is important.
Shimazui T, Ami Y, Miyanaga N
… +3 more, Ideyama Y, Nakahara T, Akaza H
Jpn J Cancer Res
· 2002 May · PMID 12036444
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Multiple occurrence or recurrence after transurethral resection is an important characteristic of superficial bladder tumors. To study bladder carcinogenesis, we focused on detection of telomerase activation, which was i...Multiple occurrence or recurrence after transurethral resection is an important characteristic of superficial bladder tumors. To study bladder carcinogenesis, we focused on detection of telomerase activation, which was investigated in several human cancers, including bladder tumors. We experimentally examined the telomerase activity during bladder carcinogenesis, especially in precancerous lesions, induced by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in rats. Male Wistar rats were given 0.05% BBN in water from the age of 8 weeks to 24 weeks. Subgroups were euthanized at 4, 8, 10, 12, 18, and 24 weeks after BBN administration. Using the stretch PCR method, telomerase activity was semiquantified in exfoliated bladder epithelial cells. In addition, telomere length in each subgroup was measured by southern hybridization for the terminal restriction fragment using a (TTAGGG)(4) probe. Statistical analyses were performed using analysis of variance and Fisher's PLSD test. Epithelial cells of normal bladder in the control groups and those of diffuse hyperplasia, which was a reversible change at 4 weeks, expressed no telomerase activity. In contrast, telomerase activity significantly increased in the stage after nodular hyperplasia, an irreversible change at 8 weeks, then elevated with carcinogenesis. However, telomere length was still preserved by the 12th week, and was shortened at 18 and 24 weeks. These results suggest that telomerase activation is probably induced independent of telomere shortening during bladder carcinogenesis in the rat, and might be a biological tumor marker of irreversible preneoplastic lesions, which evolve into bladder tumors in the rat.
Øvrebø KK, Svanes K, Aase S
… +2 more, Grong K, Sørbye H
Jpn J Cancer Res
· 2002 May · PMID 12036443
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Duodenogastric reflux is a risk factor for gastric carcinogenesis, but the pathogenesis is not fully understood. We studied the risk of N-methyl-N-nitro-N-nitrosoguanidine (MNNG)-induced carcinogenesis in the antrum of r...Duodenogastric reflux is a risk factor for gastric carcinogenesis, but the pathogenesis is not fully understood. We studied the risk of N-methyl-N-nitro-N-nitrosoguanidine (MNNG)-induced carcinogenesis in the antrum of rats with duodenogastric reflux. Duodenal fluid was directed into the stomach through the pylorus (pyloric reflux group) or through a gastrojejunostomy (jejunal reflux group). After twenty-four weeks, 5-bromo-2-deoxyuridine (BrdU) was injected intravenously and the stomach was exposed to N-(3)H-methyl-N-nitro-N-nitrosoguanidine ((3)H-MNNG). The antral mucosa was examined with immunohistochemistry and autoradiography for identification of proliferating cells (BrdU labelled) and cells at risk of MNNG-induced carcinogenesis ((3)H-MNNG and BrdU-labelled cells). Duodenogastric reflux increased the number of double-labelled cells in the antral mucosa from 4.8 +/- 0.6 per mm in the control group to 11.3 +/- 1.9 in the jejunal reflux group (P < 0.05) and 12.7 +/- 0.9 in the pyloric reflux group (P < 0.05). Mucosal erosions were observed in 15 of 28 animals with pyloric reflux and the number of double-labelled cells in the erosion area (4.3 +/- 0.7) was higher than in the same area of animals without erosion (1.4 +/- 0.5) (P < 0.05). Duodeno-gastric reflux increased the cell proliferation and significantly changed the distance between the surface epithelial lining and the proliferating cells when compared to the controls. These results indicate that duodenogastric reflux increases the penetration of (3)H-MNNG into the antrum mucosa of rats. Increased cell proliferation and erosions increase the number of cells at risk of an initiation process from a penetrating gastric carcinogen.
Ochiai M, Imai H, Sugimura T
… +2 more, Nagao M, Nakagama H
Jpn J Cancer Res
· 2002 May · PMID 12036442
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2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is the most abundant heterocyclic amine contained in cooked meat and fish. Although PhIP has been demonstrated to induce various types of tumors in rats, lymphomas p...2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is the most abundant heterocyclic amine contained in cooked meat and fish. Although PhIP has been demonstrated to induce various types of tumors in rats, lymphomas predominated in mice using the CDF1 strain. To investigate the carcinogenic activity of PhIP on other organs in mice with a different genetic background, PhIP was administered to C57BL / 6N mice. After a 40-week administration of 300 ppm of PhIP in a high-fat diet followed by continuous feeding with a high fat diet, C57BL / 6N mice developed adenomas and adenocarcinomas in the small intestine, the incidences being 52% in males and 68% in females at weeks 95 and 70, respectively. Lymphomas of B-cell origin also developed in both sexes as frequently as in the CDF1 strain, incidences being 48% in males and 32% in females. Although the incidence in PhIP-treated female mice did not differ from that in the control mice, lymphomas developed significantly earlier in the PhIP-treated mice. The present study demonstrated that the intestinal tract is another potential target of PhIP-induced carcinogenesis in mice, and that the carcinogenic activity of PhIP could be affected by the genetic background of the animals.