Helicobacter pylori-induced gastric cancer is orchestrated by MRCK beta-mediated Siah2 phosphorylation

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Dixit , P , Kokate , S B , Poirah , I , Chakraborty , D , Smoot , D T , Ashktorab , H , Rout , N , Singh , S P & Bhattacharyya , A 2021 , ' Helicobacter pylori-induced gastric cancer is orchestrated by MRCK beta-mediated Siah2 phosphorylation ' , Journal of Biomedical Science , vol. 28 , no. 1 , 12 . https://doi.org/10.1186/s12929-021-00710-0

Title: Helicobacter pylori-induced gastric cancer is orchestrated by MRCK beta-mediated Siah2 phosphorylation
Author: Dixit, Pragyesh; Kokate, Shrikant B.; Poirah, Indrajit; Chakraborty, Debashish; Smoot, Duane T.; Ashktorab, Hassan; Rout, Niranjan; Singh, Shivaram P.; Bhattacharyya, Asima
Contributor organization: Institute of Biotechnology
Date: 2021-02-03
Language: eng
Number of pages: 17
Belongs to series: Journal of Biomedical Science
ISSN: 1021-7770
DOI: https://doi.org/10.1186/s12929-021-00710-0
URI: http://hdl.handle.net/10138/333525
Abstract: Background Helicobacter pylori-mediated gastric carcinogenesis is initiated by a plethora of signaling events in the infected gastric epithelial cells (GECs). The E3 ubiquitin ligase seven in absentia homolog 2 (Siah2) is induced in GECs in response to H. pylori infection. Posttranslational modifications of Siah2 orchestrate its function as well as stability. The aim of this study was to evaluate Siah2 phosphorylation status under the influence of H. pylori infection and its impact in gastric cancer progression. Methods H. pylori-infected various GECs, gastric tissues from H. pylori-infected GC patients and H. felis-infected C57BL/6 mice were evaluated for Siah2 phosphorylation by western blotting or immunofluorescence microscopy. Coimmunoprecipitation assay followed by mass spectrometry were performed to identify the kinases interacting with Siah2. Phosphorylation sites of Siah2 were identified by using various plasmid constructs generated by site-directed mutagenesis. Proteasome inhibitor MG132 was used to investigate proteasome degradation events. The importance of Siah2 phosphorylation on tumorigenicity of infected cells were detected by using phosphorylation-null mutant and wild type Siah2 stably-transfected cells followed by clonogenicity assay, cell proliferation assay, anchorage-independent growth and transwell invasion assay. Results Siah2 was phosphorylated in H. pylori-infected GECs as well as in metastatic GC tissues at residues serine(6) (Ser(6)) and threonine(279) (Thr(279)). Phosphorylation of Siah2 was mediated by MRCK beta, a Ser/Thr protein kinase. MRCK beta was consistently expressed in uninfected GECs and noncancer gastric tissues but its level decreased in infected GECs as well as in metastatic tissues which had enhanced Siah2 expression. Infected murine gastric tissues showed similar results. MRCK beta could phosphorylate Siah2 but itself got ubiquitinated from this interaction leading to the proteasomal degradation of MRCK beta and use of proteasomal inhibitor MG132 could rescue MRCK beta from Siah2-mediated degradation. Ser(6) and Thr(279) phosphorylated-Siah2 was more stable and tumorigenic than its non-phosphorylated counterpart as revealed by the proliferation, invasion, migration abilities and anchorage-independent growth of stable-transfected cells. Conclusions Increased level of Ser(6) and Thr(279)-phosphorylated-Siah2 and downregulated MRCK beta were prominent histological characteristics of Helicobacter-infected gastric epithelium and metastatic human GC. MRCK beta-dependent Siah2 phosphorylation stabilized Siah2 which promoted anchorage-independent survival and proliferative potential of GECs. Phospho-null mutants of Siah2 (S6A and T279A) showed abated tumorigenicity.
Subject: Cdc42BPB
E3 ubiquitin ligase
Gastric cancer
Helicobacter pylori
pathogen interaction
3111 Biomedicine
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion

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