2016, 40(2): 85-90. doi: 10.3760/cma.j.issn.1673-4114.2016.02.001
Objective Lung cancer cells associated with radioresistance are likely to give rise to local recurrence and distant metastatic relapse, but little is known about its underlying mechanisms. In the present paper, the effects of the HPV16 E6 and HPV16 E7 oncoprotein on the radiosensitivity of lung cancer cell lines were investigated. Methods The HPV16 E6 or HPV16 E7 oncoprotein was expressed by a transient transfection with pcDNA3-HPV16 E6 or pcDNA3-HPV16 E7 expression vector. Human lung cancer H2179 cells and mouse lung cancer Lewis cells were exposed to a γ-ray radiation source, cellular survival was evaluated by using a colony formation assay. The expression of HPV16 oncoproteins E6/E7, extracellular signal-regulated kinases 1/2(ERK1/2) and AKT signaling was determined by Western blot assay. VEGF secretion was determined by ELISA. Results Both HPV16 oncoproteins E6 and E7 significantly decreased radiosensitivity of H2179 cells, associated with a promotion of the ERK1/2 and AKT phosphorylation. A decrease of reactive oxygen species(ROS) and an increase of VEGF levels were observed in the cells expressing the HPV16 oncoproteins E6 and E7. Furthermore, a similar reduction of radiosensitivity mediated by the HPV16 oncoproteins E6 and E7 was also observed in a mouse lung cancer Lewis cells. Conclusion The findings indicate that the HPV16 oncoproteins E6 and E7 negatively affects susceptibility of lung cancer cells to radiotherapy via regulation of the ERK1/2 and Akt signaling pathway and VEGF expression.
2016, 40(5): 323-328. doi: 10.3760/cma.j.issn.1673-4114.2016.05.001
Objective To identify a novel retinoblastoma protein(RB)-associated protein(RBAP 96) and to explore the impact of RBAP96 on radiosensitivity of human breast cancer cells. Methods An in vivo and in vitro association of RBAP96 with RB was determined by immunoprecipitation-Western blotting and GST pull-down assay. Protein expression was measured by Western blot assay. Cellular survival was evaluated by using a colony formation assay. Results In both in vitro and in vivo assays, we found that the RBAP96 and RB interaction required a 513LXCXE517 motif on the RBAP96 protein and an intact A/B binding pocket of RB. RBAP96 enhances RB-mediated transcriptional repression. Finally, enforced expression of RBAP96 caused an elevated radiosensitivity of human breast cancer cells bearing wtRB, but did not affect radiosensitivity of breast cancer cells bearing mutant RB. Expression of a full-length RBAP96 with an 513LXCXE517 inactivating mutation(LXCXE→RXRXH) failed to result in any radiosensitivity alteration. Conclusion This study for the first time characterizes a novel RB-interacting protein RBAP96 and demonstrates that enforced expression of RBAP96 causes an increase of RBAP96-mediated transcription activation and radiosensitivity via a RB-interacting dependent manner.
2016, 40(2): 91-99. doi: 10.3760/cma.j.issn.1673-4114.2016.02.002
Objective A nucleosomal protein, HMGB1, can be secreted by activated immune cells or passively released by dying cells, thereby amplifying rigorous inflammatory responses. In this study we aimed to test the possibility that radiation similarly induces cytoplasmic HMGB1 translocation and release. Methods Human skin fibroblast (GM0639) and bronchial epithelial (16HBE) cells and rats were exposed to X-ray radiation, and HMGB1 translocation and release were then assessed by immunocytochemistry and immunoassay, respectively. Results At a wide dose range(4.0-12.0 Gy), X-ray radiation induced a dramatic cytoplasmic HMGB1 translocation, and triggered a time- and dose-dependent HMGB1 release both in vitro and in vivo. The radiation-mediated HMGB1 release was also associated with noticeable chromosomal DNA damage and loss of cell viability. Conclusions Radiation induces HMGB1 cytoplasmic translocation and extracellular release through active secretion and passive leakage processes.
2017, 41(3): 193-198. doi: 10.3760/cma.j.issn.1673-4114.2017.03.007
2018, 42(4): 340-345, 351. doi: 10.3760/cma.j.issn.1673-4114.2018.04.010
2019, 43(1): 61-67. doi: 10.3760/cma.j.issn.1673-4114.2019.01.011
2017, 41(5): 340-346. doi: 10.3760/cma.j.issn.1673-4114.2017.05.007
2017, 41(3): 214-219. doi: 10.3760/cma.j.issn.1673-4114.2017.03.011
2018, 42(2): 121-128. doi: 10.3760/cma.j.issn.1673-4114.2018.02.005
2018, 42(3): 248-256. doi: 10.3760/cma.j.issn.1673-4114.2018.03.010