Abstract 3475: Inhibitory effects of ZFP36L1 and ZFP36L2 on the cell proliferation in human colorectal cancer cells

Abstract

Abstract ZFP36 family members include ZFP36 (also named TTP and TIS11), ZFP36L1 (also called BRF1, ERF1 or TIS11B) and ZFP36L2 (also called BRF2, ERF2 and TIS11D), which belong to the CCCH-type zinc finger protein with 2 tandem zinc finger region (TZF). These ZFP36 family proteins can function as RNA-binding protein through binding to AU-rich elements (AREs) in the 3’ untranslated region (3’ UTR) of mRNA, which promote the mRNA degradation or translation repression. Previously, ZFP36 has been found to inhibit cell proliferation through p53-dependent manner. In this study, we’d like to investigate whether ZFP36L1and ZFP36L2 have anti-proliferative activity as same as ZFP36 work. Tetracycline-inducible (Tet-On) system was used to induce the overexpression of ZFP36L1 or ZFP36L2 proteins in T-REx-293 cells by doxycycline (Dox) treatment. While ZFP36L1 or ZFP36L2 was overexpressed, we found that cell proliferation was dramatically inhibited, but didn’t cause cell death significantly. The importance of TZF was confirmed by using TZF mutants, and found that cell proliferation was deprived in HEK-293 cells with overexpression of ZFP36L1 mutant (C135/173R). Using western blot analysis, it was revealed that expression level of p53 protein was increased after the overexpression of ZFP36L1 or ZFP36L2 protein. Whereas, the levels of cell cycle-related proteins including cyclin B1, cyclin D1, cyclin A2 and p21 were decrease. Next, three human colorectal cancer cells HCT116 p53+/+, HCT116 p53-/- and SW620 (mutated p53) cells were used and ZFP36L1 or ZFP36L2 gene was transduced into these three cells by lentivirus. Overexpression of ZFP36L1 or ZFP36L2 also inhibited the cyclin D1 protein expression and cell proliferation in these three cells, however, increased the p53 and p21 protein expression in HCT116 p53+/+ cells, and decreased the c-Myc expression only in SW620 cells. On the other hand, knockdown of ZFP36L1 or ZFP36L2 increased cell proliferation, and mutation in TZF of ZFP36L1 (C135/173R) or ZFP36L2 (C174/212R) lost their anti-proliferative abilities in these three cells. Taken together, the results suggest that ZFP36L1 and ZFP36L2 play a negative role in cell proliferation of human colorectal cancer cells, and the underlying mechanisms might be mediated through downregulation of cyclin D1 and p53-independent pathway. Citation Format: Fat-Moon Suk, Ya-Ting Chen, Yu-Chih Liang. Inhibitory effects of ZFP36L1 and ZFP36L2 on the cell proliferation in human colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3475. doi:10.1158/1538-7445.AM2017-3475