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Inhibition of cell growth and telomerase activity of breast cancer cells in vitro by retinoic acids 总被引:6,自引:0,他引:6
Choi SH Kang HK Im EO Kim YJ Bae YT Choi YH Lee KH Chung HY Chang HK Kim ND 《International journal of oncology》2000,17(5):971-976
The effects of retinoic acid (RA) and its analogs, all-trans RA, 9-cis RA and 13-cis RA, were investigated in human breast cancer MCF-7 cells and immortalized breast epithelial cell line MCF-10A. RA inhibited the telomerase activity of MCF-7 cells in a wide range of concentrations. RA at 10 microM also inhibited the growth of MCF-7 cells in a time-dependent manner. However, no significant growth inhibition was found between untreated control and RA-treated MCF-10A cells. Moreover, a marked inhibition of telomerase activity by RA was detected early in MCF-7 cells (after 24 h of RA treatment), which was preceded by a reduction of hTERT mRNA expression (after 12 h of RA treatment). However, MCF-10A cells showed a reduction of telomerase activity and down-regulation of hTERT after 4 days of RA treatment. Simultaneous changes in hTERT mRNA expression and telomerase activity were found for MCF-10A cells. The expressions of hTR and hTEP1 telomerase component genes were not changed after RA treatment. These results indicate that the anti-breast cancer activity of RA could be mediated by its ability to down-regulate the expression of hTERT telomerase gene. 相似文献
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EGCG down-regulates telomerase in human breast carcinoma MCF-7 cells, leading to suppression of cell viability and induction of apoptosis 总被引:10,自引:0,他引:10
Mittal A Pate MS Wylie RC Tollefsbol TO Katiyar SK 《International journal of oncology》2004,24(3):703-710
Telomerase is elevated in >90% of breast carcinomas and therefore has received much attention as a target for breast cancer therapy and cancer diagnostic research. Dietary components that are capable of inhibiting the growth of cancer cells without affecting the growth of normal cells are receiving considerable attention in developing novel cancer-preventive approaches. Studies have shown that (-)-epigallocatechin-3-gallate (EGCG) from green tea imparts a growth inhibitory effect on cancer cells. Here, we show that treatment of EGCG dose-dependently inhibited (20-100%) the reproductive or colony forming potential, and also decreased cell viability at different time points studied ( approximately 80% inhibition) in human breast carcinoma MCF-7 cells but had no adverse effect on the growth of normal mammary cells. Treatment of EGCG for 48 and 72 h markedly increased the percentage of apoptotic cells (32-51%) in MCF-7 cells compared to that of non-EGCG treated cells (8-14%). In order to identify the possible mechanism of decreased cell viability and induction of apoptosis in breast carcinoma cells by EGCG, we found that treatment of MCF-7 cells with EGCG dose-dependently inhibited telomerase activity (40-55%), and also inhibited the mRNA expression (40-55%) of hTERT, a catalytic subunit of telomerase. Additional studies demonstrated that EGCG also inhibited the protein expression of hTERT, which indicated that inhibition of telomerase was associated with down-regulation of hTERT. Together, our results indicate that EGCG down-regulates telomerase in human breast carcinoma MCF-7 cells, leading to the suppression of cell viability and induction of apoptosis, thus providing the molecular basis for the development of EGCG as a novel chemopreventive and pharmacologically safe agent against breast cancer. 相似文献
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Ribozyme cleavage of telomerase mRNA sensitizes breast epithelial cells to inhibitors of topoisomerase 总被引:17,自引:0,他引:17
Ludwig A Saretzki G Holm PS Tiemann F Lorenz M Emrich T Harley CB von Zglinicki T 《Cancer research》2001,61(7):3053-3061
Telomerase activity is necessary and sufficient for immortality in many cells and hence represents a prime target for antitumor strategies. Here, we show that a hammerhead ribozyme cleaves human telomerase (hTERT) mRNA in vitro. Stable transfection in clones of the human breast tumor line MCF-7 and the immortal breast cell line HBL-100 results in expression of the ribozyme, diminishes the abundance of hTERT mRNA, and inhibits telomerase activity. This led to shortened telomeres, inhibition of net growth, and induction of apoptosis. In HBL-100 mass cultures infected with a ribozyme-expressing adenovirus diminution of hTERT mRNA, attenuation of telomerase activity, inhibition of net growth, and induction of apoptosis was found as well. Attenuation of telomerase activity increased the sensitivity of HBL-100 and MCF-7 clones specifically to inhibitors of topoisomerase. Likewise, expression of exogenous telomerase in originally telomerase-negative human fibroblasts decreased their sensitivity to topoisomerase poisons but not to a number of other cytotoxic drugs. The data validate a ribozyme approach for telomerase inhibition therapy in cancer and suggest that it might be combined advantageously with topoisomerase-directed chemotherapy. 相似文献
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Differential sensitivity of human mammary epithelial and breast carcinoma cell lines to curcumin 总被引:22,自引:0,他引:22
Curcumin has anti-inflammatory, antiproliferative, and antitumor effects. To understand the chemopreventive mechanism of curcumin against human malignancies, the cellular and molecular changes induced by this agent in human mammary epithelial (MCF-10A) and breast carcinoma (MCF- 7/TH) cell lines were investigated. The human multidrug- resistant breast cancer cell line was 3.5 fold more sensitive to curcumin than the mammary epithelial cell line. Even though both cell lines accumulated a similar amount of curcumin, a significantly higher percentage of apoptotic cells was induced in breast cancer cells compared to a very low percentage of apoptosis in mammary epithelial cells. Incubation of breast cancer cells with 20 and 40 microM curcumin for 24 h induced G2 block and sub-G0/G1 cell population, respectively. Curcumin treatment caused a reduction in the expression of Ki67, PCNA, and p53 mRNAs in breast cancer cells. The human mammary epithelial cell line showed a down-regulation of p21 mRNA and an up-regulation of Bax mRNA expression with curcumin treatment. The results suggest that apoptosis is involved in the curcumin-induced inhibition of tumor cell growth, and genes associated with cell proliferation and apoptosis may be playing a role in the chemopreventive action of curcumin. 相似文献
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The Bmi-1 oncogene induces telomerase activity and immortalizes human mammary epithelial cells 总被引:41,自引:0,他引:41
Dimri GP Martinez JL Jacobs JJ Keblusek P Itahana K Van Lohuizen M Campisi J Wazer DE Band V 《Cancer research》2002,62(16):4736-4745
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Melkoumian ZK Martirosyan AR Strobl JS 《International journal of cancer. Journal international du cancer》2002,102(1):60-69
Quinidine regulates growth and differentiation in human breast tumor cells, but the immortalized mammary epithelial MCF-10A cell line is insensitive to quinidine. We found that a morphologically similar differentiation response was evoked by quinidine and c-myc antisense oligonucleotides in MCF-7 cells and this prompted us to investigate the actions of quinidine on c-myc gene expression. Myc protein levels were suppressed in human breast tumor cell lines, but not in MCF-10A cells, an observation that supports the hypothesis that suppression of c-myc gene expression is involved in the preferential growth and differentiation response of breast tumor cells to quinidine. Quinidine reduced c-myc mRNA levels in MCF-7 cells. Acute induction of c-myc mRNA by estradiol, as well as the c-myc response to sub-cultivation in fresh serum and H-ras driven elevations in c-myc mRNA were depressed by 50-60% in the presence of quinidine. Quinidine decreased c-myc promoter activity in MCF-7 cells in a transient reporter gene assay and a 168 bp region of human c-myc promoter (-100 to +68 with respect to the P1 promoter) was sufficient to confer responsiveness to quinidine. Quinidine is a potential lead compound for developing pharmacological agents to regulate Myc. In addition, the study of quinidine-regulated events is a promising approach to unravel differentiation control pathways that become disrupted in breast cancer. 相似文献
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Estrogen activates telomerase 总被引:36,自引:0,他引:36
Kyo S Takakura M Kanaya T Zhuo W Fujimoto K Nishio Y Orimo A Inoue M 《Cancer research》1999,59(23):5917-5921
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Downregulation of telomerase reverse transcriptase mRNA expression by wild type p53 in human tumor cells 总被引:33,自引:0,他引:33
Xu D Wang Q Gruber A Björkholm M Chen Z Zaid A Selivanova G Peterson C Wiman KG Pisa P 《Oncogene》2000,19(45):5123-5133