Inhibition of ATR potentiates the cytotoxic effect of gemcitabine on pancreatic cancer cells through enhancement of DNA damage and abrogation of ribonucleotide reductase induction by gemcitabine.

Abstract

Pancreatic cancer is a highly malignant disease with a dismal prognosis. Gemcitabine (GEM)-based chemotherapy is the first-line treatment for patients with advanced disease, although its efficacy is very limited, mainly due to drug resistance. Ataxia telangiectasia and Rad3-related (ATR) plays a critical role in the DNA damage response (DDR) which has been implicated in GEM resistance. Thus, targeting ATR represents a promising approach to enhance GEM antitumor activity. In the present study, we tested the antitumor activity of AZ20, a novel ATR-selective inhibitor, alone or combined with GEM in 5 pancreatic cancer cell lines. AZ20 treatment of the pancreatic cancer cell lines resulted in growth inhibition, with IC50 values ranging from 0.84 to 2.4 µM, but limited cell death. As expected, treatment of pancreatic cancer cell lines with AZ20 caused decreased phosphorylation of CHK1 (S-345). However, this was accompanied by DNA damage and S and G2/M cell cycle arrest, independent of TP53 gene mutational status. Importantly, combination of AZ20 with GEM resulted in synergistic inhibition of cell growth and cooperative induction of cell death in the pancreatic cancer cell lines. AZ20 significantly increased GEM-induced DNA damage and almost completely abrogated GEM-induced expression of the M2 subunit of ribonucleotide reductase. These findings suggest that inhibition of ATR is a promising strategy to enhance the antitumor activity of GEM for treating pancreatic cancer.

• Authors: Shuang Liu, Yubin Ge, Tingting Wang, Holly Edwards, Qihang Ren, Yiqun Jiang, Chengshi Quan, Guan Wang
• Journal: Oncology reports (Oncol Rep) Vol. 37 Issue 6 Pg. 3377-3386 (Jun 2017) ISSN: 1791-2431 [Electronic] Greece
• PMID: 28440428 (Publication Type: Journal Article)

Chemical References

• 4-(4-(3-methylmorpholin-4-yl)-6-(1-(methylsulfonyl)cyclopropyl)pyrimidin-2-yl)-1H-indole
• Morpholines
• Pyrimidines
• TP53 protein, human
• Tumor Suppressor Protein p53
• Deoxycytidine
• Ribonucleotide Reductases
• ATR protein, human
• Ataxia Telangiectasia Mutated Proteins
• CHEK1 protein, human
• Checkpoint Kinase 1
• Gemcitabine

Topics

• Apoptosis (drug effects)
• Ataxia Telangiectasia Mutated Proteins (antagonists & inhibitors, genetics)
• Cell Cycle (drug effects)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Checkpoint Kinase 1 (genetics)
• DNA Damage (drug effects)
• Deoxycytidine (administration & dosage, analogs & derivatives)
• Drug Resistance, Neoplasm (genetics)
• Gene Expression Regulation, Neoplastic (drug effects)
• Humans
• Morpholines (administration & dosage)
• Pancreatic Neoplasms (drug therapy, genetics, pathology)
• Pyrimidines (administration & dosage)
• Ribonucleotide Reductases (genetics)
• Tumor Suppressor Protein p53 (genetics)
• Gemcitabine