ATAD2 suppression enhances the combinatorial effect of gemcitabine and radiation in pancreatic cancer cells

Abstract

Amalgamation of target-based approach along with chemo and/or radiotherapy could be an effective strategy to combat pancreatic cancer (PC). ATAD2 (ATPase family AAA domain containing 2) is a potential oncoprotein and a poor prognostic factor in PC. ATAD2 inhibition sensitizes pancreatic cancer cells (PCCs) to gemcitabine (GEM). ATAD2 silencing also enhances radio-sensitivity in lung cancer cells. We therefore hypothesise that ATAD2 suppression along with application of GEM and radiation could show additive/synergistic response in reducing PC progression. At first, immunofluorescence and western blot analysis are carried out to investigate ATAD2 expression upon irradiation in PCCs (BxPC3, and PANC1). Colony forming assay is performed to analyse the radio-sensitization effect of ATAD2 suppressed PCCs in absence and presence of GEM. To evaluate the consequences of irradiation, expression of markers for DNA damage and repair as well as apoptosis and autophagy are also assessed. Results indicate that ATAD2 is elevated in irradiated PCCs. Silencing ATAD2 sensitizes PCCs to radiation. Survival fraction analysis of PCCs shows that combination treatment of GEM and radiation (with minimal doses) is more effective when ATAD2 is suppressed. Further, when GEM-radiation combination is applied to ATAD2 silenced PCCs, expression of DNA damage marker like γH2AX is induced, whereas DNA damage repair proteins (pChk1, and pChk2) are downregulated. Moreover, ATAD2 suppressed PCCs are more susceptible to apoptosis and autophagy in presence of radiation and GEM. Collectively, these findings support our hypothesis and demonstrate that targeting ATAD2 enhances efficacy of GEM-radiation treatment in PCCs.