Abstract 194: MicroRNA-1 induces apoptosis by targeting prothymosin alpha in nasopharyngeal carcinoma cells

Abstract

Abstract MiR-1 (microRNA-1) can be used as a positive control and for optimizing transfection conditions in microRNA experiments (e.g., Ambion Pre-miR miRNA Starter Kit, QIAGEN Syn-hsa-miR-1 miScript miRNA mimic positive control). We noticed that transfection of nasopharyngeal carcinoma cells with miR-1 reveals a typical apoptotic process when observed by time-lapse microscopy. Annexin V and TUNEL staining and caspase assay confirm that miR-1 induces nasopharyngeal carcinoma cell apoptosis. MiR-1 transfection of HeLa, Cal-27, KYSE30 and NPC-TW06 cell lines which express low levels of endogenous miR-1 also induces apoptosis. However, miR-1 transfection of cell lines such as SW620, HepG2, HEK-293T, SAS and PC-13 which express high levels of endogenous miR-1 does not induce apoptosis. To determine miR-1 target genes that are involved in apoptosis, we analyzed microRNA and pathway databases, and cDNA expression microarrays from miR-1 transfected cells. Using qRT-PCR analysis and luciferase reporter vector assays, we found that miR-1 directly targets PTMA (prothymosin alpha). We used PTMA siRNA to down regulate PTMA mRNA levels and observed whether PTMA siRNA could induce apoptosis. Knocking down PTMA expression alone did not induce apoptosis but could accelerate apoptotic progression in cells treated with apoptosis inducers. We also found that transfection of miR-1 could up regulated some pro-apoptotic proteins (HTRA, SMAC, p53, TNF-R1, TNF-R2, TRAILR-1, TNF-alpha, TNF-beta). They are not miR-1 directly target genes but involve in miR-1 inducing apoptosis. We conclude that miR-1 can induced apoptosis in low levels of endogenous miR-1 cell lines. This is a novel model of microRNA-induced cell apoptosis. The apoptotic inducers including actinomycin D, camptothecin and etoposide are also the chemotherapeutic drugs in clinical cancer therapy and PTMA siRNA can accelerate apoptotic progression in cells treated with those apoptosis inducers. Therefore PTMA siRNA may have potential applications as an adjuvant in cancer chemotherapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 194. doi:1538-7445.AM2012-194