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| Sensitizing effect and Mechanism of metformin on radiotherapy of lung carcinoma A549 cells |
| JIANG Chao1, ZHANG Pengcheng2, Wang Xiaowei1, GAO Yong1 |
1. Department of Oncology, Huai'an First People's Hospital, Nanjing Medical University, Huai'an 223300 China;
2. Department of Radiation Oncology, Tianjin Medical University General Hospital |
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Abstract Objective To explore the possibility that metformin enhance radiosensitivity and its potential mechanism in lung cancer A549 cells.Methods CCK8 assay was conducted to determine the IC50 value of metformin in A549 cell. The radiosensitizing effect of metformin in A549 cell on survival curve after radiation were detected by cell colony assay. Flow cytometry with Annexin V-PI staining was used to assess the apoptosis and cell cycle arrest. The expression of DNA damage proteinγ-H2AX and DNA repair protein, such as DNA-PK, Ku80, Ku70, were detected by Western Blot analysis.Results We found that metformin at 5mM concerntration enhanced the radiosensitivity of A549 cell. Cell colony assay showed that the cell survival fraction (SF) was 1.39 after radiation combined with 5 mM metformin for 24 hours, and the SF value was 0.1 in radiation alone group. Flow cytometry showed that the ratio of G2/M phase after 6Gy combined with 5mM metformin group was 8%, the early apoptotic rate was 34.9%, but its ratio of 6Gy was 26%, the early apoptotic rate was 10.6%. Western blot showed that metformin significantly down-regulated the expression of DNA repair protein such as DNA-PK, Ku70 and Ku80 and up-regulated the expression of DNA damage repair γ-H2AX protein after 6Gy combined with 5 mM metformin for 24 hours (P<0.01).Conclusion In vitro, we found that the mechanism about radiosensitivity of metformin was to reduce G2 checkpoint and inhibit DNA damage repair.
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Received: 26 July 2017
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[1] Jemal A, Siegel R, Xu J, Ward E. Cancer statistics, 2010[J].CA Cancer J Clin, 2010, 60(5):277-300.
[2] Timmerman R, Paulus R, Galvin J, et al. Stereotactic body radiation therapy for inoperable early stage lung cancer[J].JAMA, 2010,303(11):1070-1076.
[3] Wan G, Yu X, Chen P, et al. Metformin therapy associated with survival benefit in lung cancer patients with diabetes[J].Oncotarget, 2016, 7(23):35437-35445.
[4] Suwei D, Liang Z, Zhimin L, et al. NLK functions to maintain proliferation and stemness of NSCLC and is a target of metformin[J].J Hematol Oncol, 2015, 8:120.
[5] Coyle C, Cafferty FH, Vale C, et al. Metformin as an adjuvant treatment for cancer:a systematic review and meta-analysis[J].Ann Oncol, 2016, 27(12):2184-2195.
[6] Lin ZZ, Chou CH, Cheng AL, et al. Radiosensitization by combining an aurora kinase inhibitor with radiotherapy in hepatocellular carcinoma through cell cycle interruption[J].Int J Cancer, 2014,135(2):492-501.
[7] Grosse J, Warnke e, Wehland M, et al. Mechanisms of apoptosis in irradiated and sunitinib-treated follicular thyroid cancer cells[J].Apoptosis,2014,19(3):480-490.
[8] Li H, Chen X, Yu Y, et al. Metformin inhibits the growth of nasopharyngeal carcinoma cells and sensitizes the cells to radiation via inhibition of the DNA damage repair pathway[J].Oncol Rep,2014,32(6):2596-2604.
[9] H. Dixon, CJ. Norbury. Therapeutic exploitation of checkpoint defects in cancer cells lacking p53 function[J].Cell Cycle, 2002, 1(6):362-368.
[10] Zhang X, Huang Q, Wang X, et al. Bufalin enhances radiosensitivity of glioblastoma by suppressing mitochondrial function and DNA damage repair[J].Biomed Pharmacother,2017,94:627-635.
[11] Lee Y, Li HK, Masaoka A, et al. The purine scaffold Hsp90 inhibitor PU-H71 sensitizes cancer cells to heavy ion radiation by inhibiting DNA repair by homologous recombination and non-homologous end joining[J].Radiother Oncol, 2016, 121(1):162-168.
[12] Someya M, Hasegawa T, Hori M, et al. Local tumor control and DNA-PK activity of peripheral blood lymphocytes in prostate cancer patients receiving radiotherapy[J].J Radiat Res,2017,58(2):225-231. |
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