Abstract 3205: Identification of senescence-inducing microRNAs in normal human epithelial cells

Abstract

Abstract MicroRNAs (miRNAs) are novel epigenetic regulators of eukaryotic gene expression and play key roles in many cellular processes. However, the contribution of miRNAs to replicative senescence remains largely unexplored. To understand the role of miRNA in replicative senescence of normal human epithelial cells, we examined the expression profiles of 847 miRNAs in non-senescent (young) and senescent (old) normal human oral keratinocytes (NHOKs). We identified 126 senescence-associated miRNAs (SA-miRs) whose expression was altered greater than 2-fold with senescence. Among SA-miRs, 117 miRNAs (93%) were up-regulated and 9 miRNAs (7%) were down-regulated in senescent NHOKs compared to non-senescent NHOKs. miR-137 and miR-668 were consistently up-regulated with senescence of three independent NHOK cultures and with ionizing irradiation, a premature senescence inducer of NHOKs. Overexpression of miR-137 and miR-668 significantly increased senescence-associated β-galactosidase (SA β-gal) activity and senescence markers, p16INK4A and p53 in non-senescing NHOKs, indicating that they are senescence-inducing miRNAs. Furthermore, we found that these senescence-inducing miRNAs were frequently downregulated in human head and neck squamous cell carcinoma cell lines. Since senescence is considered as a tumor suppressor mechanism, the newly identified senescence-inducing miRNAs need to be considered for therapeutic application for cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3205.