Abstract LB-031: the Significant Role of 14-3-3 Sigma Including Signal Transduction, Cell Cycle Regulation, and Malignant Transformation in Human Gastric Cancer

Abstract Background: 14-3-3 protein family have many diverse functions in cellular responses including cell cycle regulation, apoptosis and malignant transformation in a broad range of organisms. 14-3-3 sigma induces G2 arrest enabling the repair of damaged DNA. Especially 14-3-3 sigma is frequently lost in tumor cells and surrounding tissues, indicate that becomes lost at an early stage in invasive cancer. The purpose of this study is to identify the role of HGF upregulated 14-3-3 sigma associated with cancer cell proliferation and invasion in gastric cancer and to identify the role of 14-3-3 sigma level in vivo by analysis 14-3-3 serum level in gastric cancer patients who underwent gastrectomy. Methods: In our study we used cell culture, Northern blotting, cDNA microarray analysis, western blotting, RT-PCR, Zymography, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, 14-3-3 sigma knock-down with short hairpin RNA (shRNA), electrophoresis mobility-shift assay, chromatin immunoprecipitation assay, Standard two chamber invasion assay. And we conducted the 14-3-3 sigma ELISA (enzyme-linked immunosorbent assay) of 37 blood samples of patients, who underwent gastrectomy for gastric cancer. Results: First, we confirmed that the expression level of 14-3-3 sigma was up-regulated by HGF(hepatocyte growth factor) in gastric cancer cell. To identify associated pathway of HGF-induced 14-3-3 sigma about MMP-1 (matrix metalloproteinase-1) expression, the cells were treated with MEK (Mitogen-activated protein kinase kinase) inhibitor(PD098059) and then analyzed by Western blotting. The HGF-mediated MMP-1 protein level was decreased with PD098059. The role for 14-3-3 sigma associated with MMP-1 was determined by knock down cell of 14-3-3 sigma. 14-3-3 sigma-sh RNA cells showed a decreased level of MMP-1, pERK and pp38. HGF-mediated cell proliferation and in vitro invasion was decreased in 14-3-3 sigma knock down cell. We also identified that 14-3-3 sigma serum level was statistically significant decreased after gastrectomy in gastric cancer patients with stage 2 or 3. (p value < 0.05) Conclusions: Our results support the hypothesis that 14-3-3 sigma plays an important role in the cell proliferation in gastric cancer, and knock down this domain, it can be preventing to gastric cancer progression. And 14-3-3 sigma serum level is associated with status of treatment locally advanced gastric cancer. Citation Format: Jiyoon Jung, Kyunghee Lee, sungae Koh, sangwoon Kim. The significant role of 14-3-3 sigma including signal transduction, cell cycle regulation, and malignant transformation in human gastric cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-031.