title: Inhibiting PI3K/Akt pathway increases DNA damage of cervical carcinoma HeLa cells by drug radiosensitization.
abstract: This study examined the role of PI3K/Akt pathway in radiosensitization of DNA damage of cervical carcinoma cells. The 50% inhibition concentration (IC50) of cisplatin and docetaxel in HeLa cells was detected by Mono-nuclear cell direct cytotoxicity assay (MTT) in vitro. HeLa cells were treated by cisplatin/docetaxel of 10 percent of IC20 alone or combined with LY294002 for 24 h, and then radiated by different doses of X-ray. The cell survival ratio was obtained by means of clone formation. One-hit multi-target model was fitted to the cell survival curve to calculate dose quasithreshold (Dq), mean lethal dose (D0), 2Gy survival fraction (SF2) and sensitization enhancement ratio (SER). The pAkt and total Akt expression was detected by Western blotting and DNA damage by neutro-comet electrophoresis. The HeLa cells were randomly divided into 7 groups in terms of different treatments: Control; radiation treatment (RT) group; LY294002+RT group; cisplatin+RT group; docetaxel+RT group; LY294002+cisplatin+RT group; LY294002+docetaxel+RT group. The apoptosis ratio of each group was measured by flow cytometry. The results showed that docetaxel and cisplatin significantly enhanced the phosphorylation of Akt in radiation-treated HeLa cells. The Dq, D0 and SF2 in LY294002-contained groups were lower than those in docetaxel or cisplatin+RT group. The SER in the LY294002+docetaxel+RT group was 1.35 times that of the docetaxel+RT group, and that in the LY294002+cisplatin+RT group 1.26 times that of the cisplatin+RT group. The Comet electrophoresis showed that tail distance in the LY294002+cisplatin+RT group or LY294002+docetaxel+ RT group was longer than in the cisplatin+RT group or docetaxel+RT group. The apoptosis ratio in the LY294002+cisplatin+RT group or LY294002+docetaxel +RT group was higher than in the cisplatin+RT group or docetaxel+RT group. It was concluded that inhibiting PI3K/Akt pathway can increase the effect of docetaxel and cisplatin on the radiosensitivity of HeLa cells and DNA damage resulted from radiation.
authors.affiliation: Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China. xiashu1900@126.com
authors.forename: Shu
authors.initials: S
authors.lastname: Xia
authors.forename: Shiying
authors.initials: S
authors.lastname: Yu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Fu
authors.forename: Fei
authors.initials: F
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.forename: Xiugen
authors.initials: X
authors.lastname: Fu
authors.forename: Yin
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D017209:Apoptosis; D002945:Cisplatin / Q000494:pharmacology; D004249:DNA Damage; D000077143:Docetaxel; D006367:HeLa Cells; D006801:Humans; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D015398:Signal Transduction; D043823:Taxoids / Q000494:pharmacology
chemical_list: D011838:Radiation-Sensitizing Agents; D043823:Taxoids; D000077143:Docetaxel; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D002945:Cisplatin