Gemcitabine and ATR inhibitors synergize to kill PDAC cells by blocking DNA damage response

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Gemcitabine (GEM) is a primary chemotherapy for pancreatic cancer but often encounters chemoresistance.
• Clinical trials explore GEM combined with targeted drugs, yet mechanistic evidence is often lacking.
• Pancreatic ductal adenocarcinoma (PDAC) remains a challenging malignancy with limited treatment options.

Purpose of the Study:

• To identify effective drug combinations with Gemcitabine for pancreatic cancer treatment.
• To investigate the synergistic effects of clinical inhibitors with GEM in PDAC cell lines.
• To elucidate the molecular mechanisms underlying drug synergy in pancreatic cancer.

Main Methods:

• Phenotypic screening of 13 human PDAC cell lines against GEM combined with 146 clinical inhibitors.
• Dose-dependent phosphoproteome profiling of four ATR inhibitors after GEM-induced DNA damage.
• Analysis of DNA damage response pathway, including CHEK1 phosphorylation.

Main Results:

• Significant synergy was observed between GEM and the ATR kinase inhibitor Elimusertib across most PDAC cell lines.
• ATR inhibition strongly blocked the DNA damage response pathway, evidenced by reduced phosphorylation of CHEK1 (pS468).
• This molecular blockade explains the synergistic effect of combining GEM with ATR inhibitors.

Conclusions:

• The combination of Gemcitabine and ATR inhibition presents a strong therapeutic rationale for treating PDAC patients.
• This study provides a robust dataset for further research into effective pancreatic cancer drug combinations.
• Targeting the DNA damage response pathway with ATR inhibitors offers a promising strategy to overcome GEM resistance.