MiR-375 activates p21 and suppresses telomerase activity by coordinately regulating HPV E6/E7, E6AP, CIP2A, and 14-3-3?.
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ABSTRACT: While microRNAs (miRNAs) are extensively studied in post-transcriptional regulation of gene expressions in many biological processes, cellular miRNA-mediated regulation of viral genes remains unclear. In particular, the interplay between human papillomavirus (HPV) genes and miRNAs and how these interactions contribute to HPV-associated cancers remain elusive.Transient transfection of miR-375-mimic was used to compensate the loss-of-function of miR-375 in HPV-positive cancer. Regulation of oncogenic molecules and their downstream molecules via miR-375 in HPV-positive cancer was investigated using qRT-PCR, western blot, dual luciferase assay, indirect immunofluorescence analysis. All experiments were conducted at least three times to achieve statistical significance determined by Student t-test.In this study, we demonstrated how miR-375 negatively regulates HPV16 and 18 transcripts. We also found a cellular protein, E6-associated protein (E6AP), directly regulated by miR-375. miR-375-mediated repression of HPV transcripts and E6AP elevated major tumor suppressors p53, p21, and retinoblastoma protein 1 (RB). Cooperative regulation of miR-375 targets along with the increase of tumor suppressors led to ~60% reduction of telomerase reverse transcriptase (TERT) transcription followed by ~35% decrease of telomerase activity. Furthermore, miR-375-mediated regulation of 14-3-3? contributes to decrease telomerase activity by altering nuclear translocation of TERT.Taken together, miR-375-mediated suppression of multiple oncogenic components in HPV-associated carcinogenesis generates a cumulative biological response to rescue key tumor suppressors and diminish telomerase activity, which results in cell cycle arrest and cell proliferation inhibition.
SUBMITTER: Jung HM
PROVIDER: S-EPMC4021670 | biostudies-other | 2014 Apr
REPOSITORIES: biostudies-other
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