Abstract 2471: Direct down-regulation of eEF1A2 by Tumor suppressor p16INK4a inhibits cancer cell growth

Abstract

Abstract The tumor suppressor protein p16INK4a is a member of the INK4 family of cyclin-dependent kinase (Cdk) inhibitors, which are involved in the regulation of the eukaryotic cell cycle. However, the mechanisms underlying the anti-proliferative effects of p16INK4a have not been fully elucidated. Using yeast two-hybrid screening, we identified the eukaryotic elongation factor (eEF)1A2 as a novel interacting partner of p16INK4a. eEF1A2 is thought to function as an oncogene in cancers. The p16INK4a protein interacted with all but the D2 (250-327 aa) domain of eEF1A2. Computational docking study predicted that D24/D131 residues of p16INK4a interacted with eEF1A2 and it was confirmed by pull-down assay with mutant p16INK4a (D24A/D131E). Ectopic expression of p16INK4a decreased the expression of eEF1A2 and inhibited cancer cell growth. Furthermore, suppression of protein synthesis by expression of p16INK4a ex vivo was verified by luciferase reporter activity. Microinjection of p16INK4a mRNA into the cytoplasm of Xenopus embryos suppressed the luciferase mRNA translation, whereas the combination of p16INK4a and morpholino-eEF1A2 resulted in a further reduction in translational activity. We conclude that the interaction of p16INK4a with eEF1A2, and subsequent downregulation of the expression and function of eEF1A2 is a novel mechanism explaining the anti-proliferative effects of p16INK4a. Citation Format: Mee-Hyun Lee, Bu Young Choi, Yong-Yeon Cho, Myoung Ok Kim, Sung-Hyun Kim, Cheol-Jung Lee, Ji Hong Song, Ann M. Bode, Zigang Dong, Yong-Joon Surh. Direct down-regulation of eEF1A2 by Tumor suppressor p16INK4a inhibits cancer cell growth. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2471. doi:10.1158/1538-7445.AM2014-2471