RT Journal Article
SR Electronic
T1 Combined inhibition of Wee1 and PARP1/2 for radiosensitization in pancreatic cancer
JF Clinical Cancer Research
JO Clin Cancer Res
FD American Association for Cancer Research
DO 10.1158/1078-0432.CCR-14-1038
A1 Karnak, David
A1 Engelke, Carl
A1 Parsels, Leslie A
A1 Kausar, Tasneem
A1 Wei, Dongping
A1 Robertson, Jordan
A1 Marsh, Katherine
A1 Davis, Mary
A1 Zhao, Lili L.
A1 Maybaum, Jonathan
A1 Lawrence, Theodore S
A1 Morgan, Meredith A.
YR 2014
UL http://clincancerres.aacrjournals.org/content/early/2014/08/12/1078-0432.CCR-14-1038.abstract
AB Purpose: While the addition of radiation to chemotherapy improves survival in patients with locally advanced pancreatic cancer, more effective therapies are urgently needed. Thus, we investigated the radiosensitizing efficacy of the novel drug combination of Wee1 and PARP1/2 [poly (ADP-ribose) polymerase 1/2] inhibitors (AZD1775 and olaparib, respectively) in pancreatic cancer. Experimental Design: Radiosensitization of AsPC-1 or MiaPaCa-2 human pancreatic cancer cells was assessed by clonogenic survival and tumor growth assays. Mechanistically, the effects of AZD1775, olaparib, and radiation on cell cycle, DNA damage (γH2AX) and HRR (homologous recombination repair) were determined. Results: Treatment of AsPC-1 and MiaPaCa-2 cells with either AZD1775 or olaparib caused modest radiosensitization while treatment with the combination significantly increased radiosensitization. Radiosensitization by the combination of AZD1775 and olaparib was associated with G2 checkpoint abrogation and persistent DNA damage. In addition, AZD1775 inhibited HRR activity and prevented radiation-induced Rad51 focus formation. Finally, in vivo, in MiaPaCa-2-derived xenografts, olaparib did not radiosensitize, while AZD1775 produced moderate, yet significant, radiosensitization (P<0.05). Importantly, the combination of AZD1775 and olaparib produced highly significant radiosensitization (P<0.0001) evidenced by a 13-day delay in tumor volume doubling (vs radiation alone) and complete eradication of 20% of tumors. Conclusions: Taken together, these results demonstrate the efficacy of combined inhibition of Wee1 and PARP inhibitors for radiosensitizing pancreatic cancers and support the model that Wee1 inhibition sensitizes cells to PARP inhibitor-mediated radiosensitization through inhibition of HRR and abrogation of the G2 checkpoint, ultimately resulting in unrepaired, lethal DNA damage and radiosensitization.