Abstract 3345: MAZ is a downstream target of CCN1 and promotes aggressive behavior of pancreatic cancer cells via CRAF-ERK signaling pathway

Abstract

Abstract MAZ (Myc-associated zinc-finger protein) is a transcription factor with dual roles in transcription initiation and termination. Deregulation of MAZ expression has been shown to associate with the progression of pancreatic ductal adenocarcinoma cancer (PDAC). However, underlying mechanisms of action of MAZ in PDAC progression are largely unknown. Here we present evidence that MAZ mRNA expression and protein level were increased in human PDAC cell lines, tissue samples, subcutaneous tumor xenograft model in a nude mouse, and spontaneous cancer in the genetically engineered PDAC mouse model. We found that MAZ is predominantly expressed in pancreatic cancer stem cells. Functional analysis demonstrates that the depletion of MAZ in PDAC cells results in inhibition of invasive phenotypes such as phenotypic shift, migration, invasion, and the sphere-forming ability of PDAC cells. Mechanistically, we found no direct effect of MAZ on the expression of K-Ras mutants, but evidently MAZ increases the activity of CRAF-ERK-signaling, which is a downstream signaling target of K-Ras. Activation of CRAF-ERK-signaling by MAZ is mediated via p21-activated protein kinases (PAK) and protein kinase B (AKT/PKB) signaling cascades and promotes invasive phenotypes of PDAC cells. Moreover, a matricellular oncoprotein CCN1 regulates MAZ expression in PDAC cells. Thereby, we proposed that CCN1-induced expression of MAZ promotes invasive phenotypes of PDAC cells is not through direct K-Ras activation as presently thought but instead through the activation of CRAF-ERK signals. Collectively, these studies highlight key players that could help in clinical management, prognosis, and therapeutic strategies. This project is funded by VA Merit Award grants (SB & SKB). Citation Format: Gargi Maity, Inamul Haque, Arnab Ghosh, Gopal Dhar, Vijayalaxmi Gupta, Sandipto Sarkar, Imaan Azeem, Douglas McGregor, Abhishek Choudhary, Donald R Campbell, Sushanta K. Banerjee, Snigdha Banerjee. MAZ is a downstream target of CCN1 and promotes aggressive behavior of pancreatic cancer cells via CRAF-ERK signaling pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3345.