Chromatin remodeling gene AT-rich interactive domain-containing protein 1A suppresses gastric cancer cell proliferation by targeting PIK3CA and PDK1

Qian Zhang,Jie Wang,Feng Liu,Xiao-Qing Wang,Shu-Jian Cui,Peng-Yuan Yang,Hai-Bo Yan,Li Feng,Ying-Hua Jiang

doi:10.18632/oncotarget.10060

Qian Zhang, Jie Wang + Show 7 more

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https://doi.org/10.18632/oncotarget.10060

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Journal: Oncotarget	Publication Date: Jun 15, 2016
Citations: 40	License type: cc-by

Affiliation: Fudan University, Yangzhou University

Abstract

The tumor suppressor gene AT-rich interactive domain-containing protein 1A (ARID1A) was frequently mutated in cancers. The modulation mechanism of ARID1A for PI3K/AKT signaling in gastric cancer (GC) remains elusive. Here, we found that depletion of endogenous ARID1A enhanced the in vitro proliferation, colony formation, cellular growth, nutrient uptake and in vivo xenograft tumor growth of GC cells. PI3K/AKT activation by ARID1A-silencing was profiled using a phospho-protein antibody array. The phosphorylation of PDK1, AKT, GSK3β and 70S6K, and the protein and mRNA expressions of PI3K and PDK1, were upregulated by ARID1A-silencing. Chromatin immunoprecipitation and luciferase reporter assay revealed that ARID1A-involved SWI/SNF complex inhibited PIK3CA and PDK1 transcription by direct binding to their promoters. Serial deletion mutation analyses revealed that the ARID1A central region containing the HIC1-binding domain, but not the ARID DNA-binding domain and the C-terminal domain, was essential for the inhibition of GC cell growth, PI3K/AKT pathway phosphorylation and its transcriptional modulation activity of PIK3CA and PDK1. The proliferation, cellular growth and glucose consumption of ARID1A-deficient GC cells were efficiently prohibited by allosteric inhibitors mk2206 and LY294002, which targeting AKT and PI3K, respectively. Both inhibitors also downregulated the phosphorylation of PI3K/AKT pathway in ARID1A-deficient GC cells. Such cells were sensitized to the treatment of LY294002, and AT7867, another inhibitor of AKT and p70S6K. The administration of LY294002 alone inhibited the in vivo growth of ARID1A- deficient GC cells in mouse xenograft model. Our study provides a novel insight into the modulatory function and mechanism of ARID1A in PI3K/AKT signaling in GC.

Highlights

Gastric cancer (GC) is the fourth and sixth most common cancer in men and women, respectively
The average cell sizes (Figure 1I and 1J, Supplementary Figure 3A and 3B) and the glucose consumptions (Figure 1K and 1L, Supplementary Figure 3C and 3D) of gastric cancer (GC) cells and Hela cells were increased significantly after AT-rich interactive domain-containing protein 1A (ARID1A) knockdown, suggesting that ARID1A depletion speeded up nutrients consumption and cellular growth
ARID1A-C1 overexpression downregulated the transcriptional activity of PDK-1-p1 promoter (Figure 3C) in AGS and SGC-7901 cells (Figure 4K). These results suggested that the region from amino acid 1202 to 1531 of ARID1A, which contains the HIC1binding domain, was essential for the regulation of PI3K/ AKT signaling in GC cells

Summary

Introduction

Gastric cancer (GC) is the fourth and sixth most common cancer in men and women, respectively. ARID1A encodes BRG1-associated factor 250 a (BAF250a), a noncatalytic subunit of the SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatinremodeling complex [18]. These mutations were prevalent for frameshifts or nonsense mutations, which will lead to mRNA decay, protein miss-folding or domain dysfunction. Loss of ARID1A expression is frequent in a variety of cancers, especially in gynecologic cancers [19, 20]. ARID1A/ BAF250a was absent in 51% of primary GCs and was significantly associated with poor prognosis [5, 21]. Kim MS et al argued that loss of ARID1A expression was not common in GC [23].

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