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  • Title: Effects of DNA methylation inhibitor on down-regulation of ribonuclease inhibitor expression in cancer cell lines.
    Author: Chen JX, Fu PF, Wang T, Cui XY.
    Journal: Ai Zheng; 2004 Nov; 23(11):1249-56. PubMed ID: 15522168.
    Abstract:
    BACKGROUND & OBJECTIVE: Human ribonuclease inhibitor (RI) could effectively block angiogenin-induced angiogenesis, and inhibit growth of transplant solid tumors in animals. However, its exact molecular mechanism of antitumor has not been totally ascertained. Many tumor suppressor genes occur loss of expression by aberrant methylation in promoter region. Demethylation, treated with methylation inhibitor 5-aza-2'-deoxycytidine (5-Aza-CdR),can restore the gene expression. To further explore functions of RI, and investigate relationship between RI and tumorigenesis, the study was designed to explore effects of 5-Aza-CdR on expression of RI in cancer cell lines. METHODS: Human breast cancer cell line MCF-7, human gastric cancer cell line BGC-823, human prostate cancer cell line DU-145, and human colon cancer cell line HT-29 were treated with 5-Aza-CdR. Expression of RI was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot, immunofluorescence, and immunocytochemistry. RESULTS: Expression of RI significantly elevated by 5-Aza-CdR at both mRNA and protein level in MCF-7, BGC-823, and DU-145 cells (P< 0.01). Compared with control cells, mRNA levels of RI in MCF-7, BGC-823, and DU-145 cells treated with 5-Aza-CdR were increased by percentages of 37.2%, 46.0%, and 32.4%, respectively; protein levels of RI were increased by percentages of 26.4%, 20.9%, and 24.4%, respectively; but no obvious change observed in HT-29 cells. CONCLUSION: RI gene may be involved in tumorigenesis of gastric, prostate, and breast cancer.
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