title: Overexpression of BRCA1 attenuates the sensitivity of PC9 cells to gefitinib.
abstract: Gefitinib is an orally active antitumor agent which inhibits uncontrolled cell proliferation by interrupting epidermal growth factor receptor (EGFR) signaling pathways. Various in vitro and in vivo studies have revealed that the upregulated expression of breast cancer susceptibility gene 1 (BRCA1) is associated with chemoresistance and reduced survival following chemotherapies. In this study, a gefitinib-highly-sensitive cell line, PC-9, was used to investigate the effect of BRCA1 expression on the sensitivity of PC-9 cells to gefitinib. PC-9 cells were stably transfected with BRCA-1 (HA-tagged). Transfected and untransfected PC-9 cells were treated with gefitinib, phosphorylated γH2AX was examined by western blot to determine the DNA damages. Following the treatment of gefitinib, the inhibition of proliferation of the PC-9 cells, PC-9-pcDNA3.1 cells, and BRCA1-transfected PC-9 cells were determined. Also, a comet assay was performed to determine the DNA damage caused by gefitinib. The treatment of gefitinib for 6 hr, 12 h, and 24 hr significantly increased the cellular expression of phosphorylated γH2AX. With the treatment of gefitinib, the inhibition of proliferation of BRCA-1 overexpressed PC-9 cells was significantly lower than that of the non-transfected PC-9 cells, indicating the overexpression of BRCA1 plays a role in attenuating the sensitivity of PC-9 cells to gefitinib. The comet assay revealed that BRCA1 transfected cells showed a shorter comet tail, indicating the overexpression of BRCA1 attenuated the DNA damages caused by gefitinib. The overexpression of BRCA1 reduced the DNA damages, and enhanced DNA repair mechanisms. Also, gefitinib-mediated inhibition of cell proliferation is attenuated by the expression of BRCA1.
authors.affiliation: Department of Head and Neck/Thoracic Medical Oncology, The First People's Hospital of Foshan Foshan 528000, Guangdong, P. R. China.
authors.forename: Weineng
authors.initials: W
authors.lastname: Feng
authors.affiliation: Department of Head and Neck/Thoracic Medical Oncology, The First People's Hospital of Foshan Foshan 528000, Guangdong, P. R. China.
authors.forename: Yanming
authors.initials: Y
authors.lastname: Deng
authors.affiliation: Institute of Oncology, The First People's Hospital of Foshan Foshan 528000, Guangdong, P. R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Head and Neck/Thoracic Medical Oncology, The First People's Hospital of Foshan Foshan 528000, Guangdong, P. R. China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Head and Neck/Thoracic Medical Oncology, The First People's Hospital of Foshan Foshan 528000, Guangdong, P. R. China.
authors.forename: Jianmao
authors.initials: J
authors.lastname: Liang
authors.affiliation: Department of Head and Neck/Thoracic Medical Oncology, The First People's Hospital of Foshan Foshan 528000, Guangdong, P. R. China.
authors.forename: Haibing
authors.initials: H
authors.lastname: Xian
authors.affiliation: Department of Head and Neck/Thoracic Medical Oncology, The First People's Hospital of Foshan Foshan 528000, Guangdong, P. R. China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Yang
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D019313:BRCA1 Protein / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D000077156:Gefitinib; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011799:Quinazolines / Q000494:pharmacology* / Q000627:therapeutic use; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D011799:Quinazolines; D000077156:Gefitinib
keywords: BRCA1; cell proliferation; gefitinib