Inhibition of GSK3B Bypass Drug Resistance of p53-Null Colon Carcinomas by Enabling Necroptosis in Response to Chemotherapy

Abstract

Purpose: Evasion from chemotherapy-induced apoptosis due to p53 loss strongly contributes to drug resistance. Identification of specific targets for the treatment of drug-resistant p53-null tumors would therefore increase the effectiveness of cancer therapy.Experimental Design: By using a kinase-directed short hairpin RNA library and HCT116p53KO drugresistant colon carcinoma cells, glycogen synthase kinase 3 beta (GSK3B) was identified as a target whose silencing bypasses drug resistance due to loss of p53. p53-null colon cancer cell lines with different sets of mutations were used to validate the role of GSK3B in sustaining resistance and to characterize cell death mechanisms triggered by chemotherapy when GSK3B is silenced. In vivo xenograft studies were conducted to confirm resensitization of drug-resistant cells to chemotherapy upon GSK3 inhibition. Colon cancer samples from a cohort of 50 chemotherapy-treated stage II patients were analyzed for active GSK3B expression.Results: Downregulation of GSK3B in various drug-resistant p53-null colon cancer cell lines abolished cell viability and colony growth after drug addition without affecting cell proliferation or cell cycle in untreated cells. Cell death of 5-fluorouracil (5FU)-treated p53-null GSK3B-silenced colon carcinoma cells occurred via PARP1-dependent and AIF-mediated but RIP1-independent necroptosis. In vivo studies showed that drug-resistant xenograft tumor mass was significantly reduced only when 5FU was given after GSK3B inhibition. Tissue microarray analysis of colon carcinoma samples from 5FU-treated patients revealed that GSK3B is significantly more activated in drug-resistant versus responsive patients.Conclusions: Targeting GSK3B, in combination with chemotherapy, may represent a novel strategy for the treatment of chemotherapy-resistant tumors.

Inhibition of Aurora Kinase A Induces Necroptosis in Pancreatic Carcinoma

“…Unlike most kinases, GSK3β is constitutively active by dephosphorylation and high levels of GSK3β activity promote cell death 39 . Our findings indicate a potential link between AURKA, GSK3β, and Wnt/β-catenin pathways in the regulation of necroptosis 28, 41, 42 .…”

MicroRNA-520g Confers Drug Resistance by Regulating p21 Expression in Colorectal Cancer

“…1D, miR-520g expression was high in FET cells with mutated p53 (35) and low in HCT116 and RKO cells with WT p53 (35,36). p53 has been implicated to contribute to 5-FU-and other chemotherapeutic drug-induced apoptosis, which involves the DNA damage response (18,37). We therefore hypothesized that p53 suppresses miR-520g expression in colon cancer cells.…”

Tumor-Related Molecular Mechanisms of Oxaliplatin Resistance

“…Although there is a lack of literature about it, in a recent work from Grassilli and colleagues, it was demonstrated that glycogen synthase 3 b (GSK3B), a serine-threonine kinase belonging to the glycogen synthase kinase subfamily that is involved in energy metabolism, neuronal cell development, and body pattern formation, was activated in almost 50% of colon carcinomas and in two thirds of drug-resistant ones. Genetic silencing of GSK3B in p53-null cells treated with oxaliplatin induced cell death by caspase-independent necroptotic death (78). It is noteworthy that oxaliplatin effectiveness has been associated with the production of ROS, which in turn is a contributor to the execution of necrosis (76).…”