Glycogen Synthase Kinase-3 Inhibition Sensitizes Pancreatic Cancer Cells to Chemotherapy by Abrogating the TopBP1/ATR-Mediated DNA Damage Response

• Published in: Clinical cancer research 2019-11, Vol.25 (21), p.6452-6462
• Main Authors: Ding, Li, Madamsetty, Vijay S, Kiers, Spencer, Alekhina, Olga, Ugolkov, Andrey, Dube, John, Zhang, Yu, Zhang, Jin-San, Wang, Enfeng, Dutta, Shamit K, Schmitt, Daniel M, Giles, Francis J, Kozikowski, Alan P, Mazar, Andrew P, Mukhopadhyay, Debabrata, Billadeau, Daniel D
• Format: Article
• Language: English
• Subjects: Adenocarcinoma - drug therapy; Adenocarcinoma - genetics; Adenocarcinoma - pathology; Animals; Apoptosis - drug effects; Ataxia Telangiectasia Mutated Proteins - genetics; Carcinoma, Pancreatic Ductal - drug therapy; Carcinoma, Pancreatic Ductal - genetics; Carcinoma, Pancreatic Ductal - pathology; Carrier Proteins - genetics; Cell Line, Tumor; Cell Proliferation - drug effects; Checkpoint Kinase 1; Deoxycytidine - analogs & derivatives; Deoxycytidine - pharmacology; DNA Damage - drug effects; DNA-Binding Proteins - genetics; Flow Cytometry; Gene Expression Regulation, Neoplastic - drug effects; Glycogen Synthase Kinase 3 beta - antagonists & inhibitors; Glycogen Synthase Kinase 3 beta - genetics; Humans; Indoles - pharmacology; Maleimides - pharmacology; Mice; Nuclear Proteins - genetics; Phosphorylation - drug effects; Protein Kinase Inhibitors - pharmacology; Signal Transduction - drug effects
• ISSN: 1078-0432; 1557-3265
• DOI: 10.1158/1078-0432.ccr-19-0799

Pancreatic ductal adenocarcinoma (PDAC) is a predominantly fatal common malignancy with inadequate treatment options. Glycogen synthase kinase 3β (GSK-3β) is an emerging target in human malignancies including PDAC. Pancreatic cancer cell lines and patient-derived xenografts were treated with a novel GSK-3 inhibitor 9-ING-41 alone or in combination with chemotherapy. Activation of the DNA damage response pathway and S-phase arrest induced by gemcitabine were assessed in pancreatic tumor cells with pharmacologic inhibition or siRNA depletion of GSK-3 kinases by immunoblotting, flow cytometry, and immunofluorescence. 9-ING-41 treatment significantly increased pancreatic tumor cell killing when combined with chemotherapy. Inhibition of GSK-3 by 9-ING-41 prevented gemcitabine-induced S-phase arrest suggesting an impact on the ATR-mediated DNA damage response. Both 9-ING-41 and siRNA depletion of GSK-3 kinases impaired the activation of ATR leading to the phosphorylation and activation of Chk1. Mechanistically, depletion or knockdown of GSK-3 kinases resulted in the degradation of the ATR-interacting protein TopBP1, thus limiting the activation of ATR in response to single-strand DNA damage. These data identify a previously unknown role for GSK-3 kinases in the regulation of the TopBP1/ATR/Chk1 DNA damage response pathway. The data also support the inclusion of patients with PDAC in clinical studies of 9-ING-41 alone and in combination with gemcitabine.