Reduced phosphorylated ATM expression is associated with poor prognosis and gemcitabine resistance in pancreatic cancer

Background & Aims: Loss of ataxia-telangiectasia mutated, occurring in patients with multiple primary malignancies, including pancreatic cancer, is associated with poor prognosis. This study investigated the detailed molecular mechanism through which ataxia-telangiectasia mutated expression affects the prognosis of pancreatic-cancer patients Methods: Ataxia-telangiectasia mutated and phosphorylated ataxia-telangiectasia mutated levels in pancreatic-cancer patients who underwent surgical resection were analyzed using immunohistochemistry staining. RNA sequencing was performed on ataxia-telangiectasia mutated-knockdown pancreatic-cancer cells to elucidate the mechanism underlying the involvement of ataxia-telangiectasia mutated in pancreatic cancer. Results: Immunohistochemical analysis showed that 15.3% and 27.8% of clinical samples had low levels of ataxia-telangiectasia mutated and phosphorylated ataxia-telangiectasia mutated, respectively. Low phosphorylated ataxia-telangiectasia mutated expression substantially reduced overall and disease-free survival in pancreatic-cancer patients. Loss of ataxia-telangiectasia mutated promoted MET and NTN1 over-expression via hypoxia-inducible factor-1α, thereby enhancing pancreatic-cancer cell proliferation and migration. Conclusions: These results demonstrate that the loss of ataxia-telangiectasia mutated activates downstream proto-oncogenes, inhibits apoptosis, and promotes tumor growth; moreover, loss of phosphorylated ataxia-telangiectasia mutated leads to poor prognosis in pancreatic-cancer patients. Thus, ataxia-telangiectasia mutated may serve as a potential molecular marker to monitor patient prognosis and as a potential target for pancreatic cancer therapy RNA expression profile of ATM-knockdown MIA-PaCa2 and SUIT-2 cells. Total RNA was extracted from the ATM-knockdown MIA-PaCa2 and SUIT-2 cells.