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Loss of mismatch repair activity in simian virus 40 large T antigen–immortalized BPH-1 human prostatic epithelial cell line

Authors

  • Che-Chung Yeh,

    1. Department of Urology, Veterans Affairs Medical Center and University of California, San Francisco, California
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  • Celeste Lee,

    1. Department of Urology, Veterans Affairs Medical Center and University of California, San Francisco, California
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  • Mei-Chuan Huang,

    1. Department of Pediatrics, University of California, San Francisco, California
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  • Rajvir Dahiya

    Corresponding author
    1. Department of Urology, Veterans Affairs Medical Center and University of California, San Francisco, California
    • Professor and Director of Urology Research Center (112F), University of California at San Francisco and San Francisco VA Medical Center, 4150 Clement Street, San Francisco, CA 94121.
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Abstract

Simian virus 40 large T antigen (SVLTAg) has been used to immortalize cells; however, the mechanism leading to immortalization is still unclear. We hypothesize that DNA mismatch repair (MMR) activity is important during SVLTAg-induced immortalization. To test this hypothesis, we used the SVLTAg-immortalized cell line BPH-1 derived from human benign prostate epithelial cells to analyze MMR activity and the expression of MMR genes (hMLH1, hPMS1, hPMS2, hMSH2, hMSH3, and hMSH6). The results demonstrated that BPH-1 cells were deficient in repairing G:T, A:C, and G:G mispairs in bacteriophage M13mp2. Reverse-transcription polymerase chain reaction experiments indicated MMR genes (hMSH3, hMSH6, and hPMS1) were expressed at a low level in BPH-1 cells. In contrast, all six MMR genes were expressed in human benign prostate hyperplasia tissues. Downregulation of hMSH3, hMSH6, and hPMS1 genes is not a result of the hypermethylation mechanism because demethylation with 5-aza-2′-deoxycytidine did not restore expression of these genes. Although the hMLH1 gene is expressed in BPH-1 cells, western blotting and exon analyses demonstrated that hMLH1 was mutated and/or deleted in BPH-1 cells. © 2001 Wiley-Liss, Inc.

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