Wei Zhao1,2, Hongbo Hu1,3, Qiyan Mo1, Ying Guan1, Ye Li1, Youqing Du1, Ling Li1. 1. Department of Radiation Oncology, Affiliated Tumor Hospital of Guangxi Medical University Nanning, Guangxi Autonomous Region, China. 2. Guangxi Colleges and Universities Key Laboratory of Biological Molecular Medicine Research Nanning, Guangxi Autonomous Region, China. 3. Department of Oncology, The People's Hospital of Chongzuo City Longxiashan Road, Chongzuo, Guangxi Autonomous Region, China.
Abstract
OBJECTIVE: To study the function and mechanism of combined PARP-1 and BRCA genes in regulating the radiosensitivity of breast cancer cells by poly ADP-ribose polymerase-1 (PARP-1) inhibitor 3-amion benzamide (3-AB) onBRCA mutant and non-mutant breast cancer cells. METHODS: Four groups of BRCA mutant cells MDA-MB-436 and BRCA non-mutant cells MDA-MB-231 were divided respectively into control (CTRL), ionizing radiation alone (IR), 3-AB alone (3-AB), and ionizing radiation combined with 3-AB (IR+3-AB) groups. The γ-H2AX foci were detected by immunofluorescence assay to show the DNA double-strand damage. The clonogenic cell survival assay was applied to evaluate the radiosensitivity of breast cancer cells, and flow cytometry was used to assess the percentage of apoptosis cells. RESULTS: The apoptosis rate of MDA-MB-436 cells was significantly increased compared with MDA-MB-231 cells treated with irradiation, and 3-AB could further enhance the effect. Similarly, the result of γ-H2AX foci detection showed that DNA double-stranded damage of the MDA-MB-436 cells was significantly greater than that of MDA-MB-231 cells (t = 4.57, P < 0.05), and the DNA damage of MDA-MB-436 cells in IR+3-AB group was the most remarkable. The difference was significant (t = 3.26, P < 0.05). In the same group, compared with MDA-MB-231 cells, MDA-MB-436 cells had the significantly greater apoptosis rate (t = 2.96, P < 0.05). The apoptosis rate of MDA-MB-436 cells in the IR+3-AB group showed by flow cytometry was highest (t = 3.81, P < 0.05). CONCLUSIONS: Compared with non-BRCA mutant MDA-MB-231 cells, the BRCA mutant breast cancer MDA-MB-436 cells could incur significantly greater DNA damage, and therefore the radiosensetivity of MDA-MB-436 cells is higher than that of MDA-MB-231 cells. The inhibitor of PARP-1, which can block the repair of single-strand damage caused by radiation, can further enhance the level of apoptosis and radiosensitivity of BRCA-mutant cells. IJCEP
OBJECTIVE: To study the function and mechanism of combined PARP-1 and BRCA genes in regulating the radiosensitivity of breast cancer cells by poly ADP-ribose polymerase-1 (PARP-1) inhibitor 3-amion benzamide (3-AB) onBRCA mutant and non-mutant breast cancer cells. METHODS: Four groups of BRCA mutant cells MDA-MB-436 and BRCA non-mutant cells MDA-MB-231 were divided respectively into control (CTRL), ionizing radiation alone (IR), 3-AB alone (3-AB), and ionizing radiation combined with 3-AB (IR+3-AB) groups. The γ-H2AX foci were detected by immunofluorescence assay to show the DNA double-strand damage. The clonogenic cell survival assay was applied to evaluate the radiosensitivity of breast cancer cells, and flow cytometry was used to assess the percentage of apoptosis cells. RESULTS: The apoptosis rate of MDA-MB-436 cells was significantly increased compared with MDA-MB-231 cells treated with irradiation, and 3-AB could further enhance the effect. Similarly, the result of γ-H2AX foci detection showed that DNA double-stranded damage of the MDA-MB-436 cells was significantly greater than that of MDA-MB-231 cells (t = 4.57, P < 0.05), and the DNA damage of MDA-MB-436 cells in IR+3-AB group was the most remarkable. The difference was significant (t = 3.26, P < 0.05). In the same group, compared with MDA-MB-231 cells, MDA-MB-436 cells had the significantly greater apoptosis rate (t = 2.96, P < 0.05). The apoptosis rate of MDA-MB-436 cells in the IR+3-AB group showed by flow cytometry was highest (t = 3.81, P < 0.05). CONCLUSIONS: Compared with non-BRCA mutant MDA-MB-231 cells, the BRCA mutant breast cancerMDA-MB-436 cells could incur significantly greater DNA damage, and therefore the radiosensetivity of MDA-MB-436 cells is higher than that of MDA-MB-231 cells. The inhibitor of PARP-1, which can block the repair of single-strand damage caused by radiation, can further enhance the level of apoptosis and radiosensitivity of BRCA-mutant cells. IJCEP