摘要
Objective:We aimed to investigate the radiosensitizing efficacy of the poly-ADP-ribose polymerase(PARP)inhibitor,olaparib,and the Bloom syndrome protein(BLM)helicase inhibitor,ML216,in non-small cell lung cancer(NSCLC)cells.Methods:Radiosensitization of NSCLC cells was assessed by colony formation and tumor growth assays.Mechanistically,the effects of ML216,olaparib,and radiation on cell and tumor proliferation,DNA damage,cell cycle,apoptosis,homologous recombination(HR)repair,and non-homologous end joining(NHEJ)repair activity were determined.Results:Both olaparib and ML216 enhanced the radiosensitivities of olaparib-sensitive H460 and H1299 cells,which was seen as decreased surviving fractions and Rad51 foci,increased total DNA damage,andγH2AX and 53BP1 foci(P<0.05).The expressions of HR repair proteins were remarkably decreased in olaparib-treated H460 and H1299 cells after irradiation(P<0.05),while olaparib combined with ML216 exerted a synergistic radiosensitization effect on olaparib-resistant A549 cells.In addition to increases of double strand break(DSB)damage and decreases of Rad51 foci,olaparib combined with ML216 also increased pDNA-PKcs(S2056)foci,abrogated G2 cell cycle arrest,and induced apoptosis in A549 lung cancer after irradiation in vitro and in vivo(P<0.05).Moreover,Western blot showed that olaparib combined with ML216 and irradiation inhibited HR repair,promoted NHEJ repair,and inactivated cell cycle checkpoint signals both in vitro and in vivo(P<0.05).Conclusions:Taken together,these results showed the efficacy of PARP and BLM helicase inhibitors for radiosensitizing NSCLC cells,and supported the model that BLM inhibition sensitizes cells to PARP inhibitor-mediated radiosensitization,as well as providing the basis for the potential clinical development of this combination for tumors intrinsically resistant to PARP inhibitors and radiotherapy.
基金
supported by grants from the National Natural Science Foundation of China(Grant Nos.31670859,81772243,81803172,81803167,31800703,and 31900889)
the CAMS Innovation Fund for Medical Science(Grant No.2017-I2M-1-016)
the China Postdoctoral Science Foundation(Grant No.2018M630106)
the Natural Science Foundation of Tianjin(Grant Nos.18JCYBJC26800,18JCQNJC12300,and 17JCYBJC42700)
the Fundamental Research Funds for the Central Universities(Grant No.10023201601602)
the Non-profit Central Research Institute Fund of the Chinese Academy of Medical Sciences(Grant Nos.2017-1001-08 and 2018RC310020)
the Key R&D Program of Shandong Province(Grant No.2019GSF107056).
