LAUSR

Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer with limited therapeutic options and a dismal long-term survival. The upregulation of KIF11, a motor protein that regulates cell mitosis, has been associated with the aggressive proliferation of pancreatic cancer cells. A molecular strategy to counteract the hyperactivity of KIF11 may represent a potential means to treat PDAC. We previously identified MG53, a member of the tripartite motif family protein (TRIM72), as an important component of tissue repair, and revealed its potential application in regenerative medicine. So far, most published studies have focused on the cytosolic and vesicle-trafficking function of MG53, little is known on the nuclear action of MG53 in pancreatic tumor suppression. In the present study, our confocal imaging revealed frequent appearance of MG53 in the nucleus of human pancreatic cancer cells, and subcellular fractionation assay showed that a majority of MG53 protein was present in the nuclear fraction. Decreased MG53 and increased KIF11 protein expression were observed in both pancreatic cancer cell lines (PANC-1 and mPanc96) and PDAC tissue from surgically resected tumors. Overexpressing MG53 inhibited colony formation and proliferation of PANC-1 cells with significant reduction of KIF11 expression. Furthermore, we demonstrated that MG53-mediated control of KIF11 expression occurs at the gene transcription level. Chromatin immunoprecipitation demonstrated an interaction between MG53 and the promoter of KIF11 in PANC-1 cells. Using a luciferase cell reporter driven by the KIF11 promoter, we found that overexpressing MG53 led to downregulation of the KIF11 transcription activity, and induced cell cycle arrest at the G2/M phase. We also conducted syngeneic orthotopic transplantation of a mouse pancreatic cancer cell line, KPC cells derived from pancreatic tumor in KRasG12D/Trp53-/-/Pdx-1-Cre (KPC) mice, into the pancreas of wild type (WT) and mg53-/- (MG53-KO) mice, which showed aggressive pancreatic tumor growth in MG53-KO mice compared with WT mice after 3-week of transplantation. Western blots revealed that a considerable amount of MG53 protein was found in the pancreatic tumors derived from KPCs in WT mice vs. those in MG53-KO mice, indicating the accumulation of circulating MG53 during tumor growth. Overall, these findings demonstrated that MG53 functions as a tumor suppressor to inhibit cancer cell proliferation and the tumor growth through transcriptional down-regulating the expression of KIF11 in pancreatic cancer, and provided a new therapeutic target for the treatment of patients with PDAC. Citation Format: Xiao-Liang Wang, Xiangfei He, Zobeida Cruz-Monserrate, Allen Tsung, Jianjie Ma, Chuanxi Cai. MG53 suppresses the tumor growth via transcriptional inhibiting the expression of KIF11 in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1729.