Inhibition of non-homologous end joining repair impairs pancreatic cancer growth and enhances radiation response.
Pancreatic ductal adenocarcinoma (PDAC) is amongst the deadliest of human cancers, due to its late diagnosis as well as its intense resistance to currently available therapeutics. To identify mechanisms as to why PDAC are refractory to DNA damaging cytoxic chemotherapy and radiation, we performed a global interrogation of the DNA damage response of PDAC. We find that PDAC cells generally harbor high levels of spontaneous DNA damage. Inhibition of Non-Homologous End Joining (NHEJ) repair either pharmacologically or by RNAi resulted in a further accumulation of DNA damage, inhibition of growth, and ultimately apoptosis even in the absence of exogenous DNA damaging agents. In response to radiation, PDAC cells rely on the NHEJ pathway to rapidly repair DNA double strand breaks. Mechanistically, when NHEJ is inhibited there is a compensatory increase in Homologous Recombination (HR). Despite this upregulation of HR, DNA damage persists and cells are significantly more sensitive to radiation. Together, these findings support the incorporation of NHEJ inhibition into PDAC therapeutic approaches, either alone, or in combination with DNA damaging therapies such as radiation.
Division of Genomic Stability and DNA Repair, Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA.
Ying-Hua
YH
Li
Xiaoxu
X
Wang
Yunfeng
Y
Pan
Dong-Hyun
DH
Lee
Dipanjan
D
Chowdhury
Alec C
AC
Kimmelman
D021441:Carcinoma, Pancreatic Ductal / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects; D004249:DNA Damage; D059766:DNA End-Joining Repair / Q000187:drug effects; D051747:DNA-Activated Protein Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D009025:Morpholines / Q000494:pharmacology; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000378:metabolism; D011836:Radiation Tolerance / Q000235:genetics*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology; D011995:Recombination, Genetic
C479235:2-(morpholin-4-yl)benzo(h)chromen-4-one; D002867:Chromones; D009025:Morpholines; D011838:Radiation-Sensitizing Agents; D051747:DNA-Activated Protein Kinase