Baiyao Wang1, Xiaoting Huang1, Huiping Liang1, Hongli Yang2, Zhaoze Guo3, Meiling Ai1, Jian Zhang1, Muhammad Khan1, Yunhong Tian1, Quanquan Sun4, Zixu Mao5, Ronghui Zheng1, Yawei Yuan6. 1. Department of Radiation Oncology, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou, Guangdong Province, People's Republic of China. 2. Department of Radiation Oncology, Shenzhen People's Hospital, Shenzhen, Guangdong Province, People's Republic of China. 3. Breast Center, Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, People's Republic of China. 4. Department of Radiation Oncology, Zhejiang Cancer Hospital, Hangzhou, Zhejiang Province, People's Republic of China. 5. Department of Pharmacology and Chemical Biology, School of Medicine, Emory University, Atlanta, Georgia. 6. Department of Radiation Oncology, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou, Guangdong Province, People's Republic of China. Electronic address: yuanyawei@gzhmu.edu.cn.
Abstract
PURPOSE: Polo-like kinase 1 (PLK1) is a protein kinase that is overexpressed in breast cancer and may represent an attractive target for breast cancer treatment. However, few studies have investigated the relationship between PLK1 and radiosensitivity in breast cancer. Here, we attempted to explore whether PLK1 inhibition could sensitize breast cancer cells to radiation. METHODS AND MATERIALS: Breast cancer cells were treated with PLK1 small interference RNA or the PLK1-inhibitor, GSK461364. Cell proliferation was assessed using a colony formation assay. Cell cycle analyses were performed by flow cytometry. DNA damage, autophagy, and reactive oxygen species induced by ionizing radiation were detected by immunofluorescence, Western blot, and flow cytometry, respectively. Microtubule-associated protein 1 light chain 3 alpha (LC3) puncta were detected using an immunofluorescence assay. A clonogenic survival assay was used to determine the effect of PLK1 inhibition on cell radiosensitivity. A xenograft mouse model of breast cancer cells was used to investigate the potential synergistic effects of PLK1 inhibition and irradiation in vivo. Finally, the expression of PLK1 and LC3 in the breast cancer tissues was evaluated by immunohistochemistry. RESULTS: PLK1 inhibition significantly suppressed the proliferation and increased the radiosensitivity of breast cancer cells. Pharmacologic inhibition of PLK1 by the selective inhibitor, GSK461364, enhanced the radiosensitivity of breast cancer cells in vivo (n = 4, P = .002). Mechanistically, PLK1 inhibition led to the downregulation of radiation-induced reactive oxygen species and autophagy, thereby increasing the radiosensitivity of breast cancer cells. Additionally, we detected a positive correlation between the expression of PLK1 and LC3 in human breast cancer samples (n = 102, R = 0.486, P = .005). CONCLUSIONS: Our findings indicate that PLK1 inhibition enhances the radiosensitivity of breast cancer cells in a manner associated with the suppression of radiation-induced autophagy. The inhibition of PLK1 represents a promising strategy for radiosensitizing breast cancer.
PURPOSE:Polo-like kinase 1 (PLK1) is a protein kinase that is overexpressed in breast cancer and may represent an attractive target for breast cancer treatment. However, few studies have investigated the relationship between PLK1 and radiosensitivity in breast cancer. Here, we attempted to explore whether PLK1 inhibition could sensitize breast cancer cells to radiation. METHODS AND MATERIALS: Breast cancer cells were treated with PLK1 small interference RNA or the PLK1-inhibitor, GSK461364. Cell proliferation was assessed using a colony formation assay. Cell cycle analyses were performed by flow cytometry. DNA damage, autophagy, and reactive oxygen species induced by ionizing radiation were detected by immunofluorescence, Western blot, and flow cytometry, respectively. Microtubule-associated protein 1 light chain 3 alpha (LC3) puncta were detected using an immunofluorescence assay. A clonogenic survival assay was used to determine the effect of PLK1 inhibition on cell radiosensitivity. A xenograft mouse model of breast cancer cells was used to investigate the potential synergistic effects of PLK1 inhibition and irradiation in vivo. Finally, the expression of PLK1 and LC3 in the breast cancer tissues was evaluated by immunohistochemistry. RESULTS:PLK1 inhibition significantly suppressed the proliferation and increased the radiosensitivity of breast cancer cells. Pharmacologic inhibition of PLK1 by the selective inhibitor, GSK461364, enhanced the radiosensitivity of breast cancer cells in vivo (n = 4, P = .002). Mechanistically, PLK1 inhibition led to the downregulation of radiation-induced reactive oxygen species and autophagy, thereby increasing the radiosensitivity of breast cancer cells. Additionally, we detected a positive correlation between the expression of PLK1 and LC3 in humanbreast cancer samples (n = 102, R = 0.486, P = .005). CONCLUSIONS: Our findings indicate that PLK1 inhibition enhances the radiosensitivity of breast cancer cells in a manner associated with the suppression of radiation-induced autophagy. The inhibition of PLK1 represents a promising strategy for radiosensitizing breast cancer.
Authors: Yiguan Qian; Yang Li; Ke Chen; Ning Liu; Xi Hong; Di Wu; Zheng Xu; Liuhua Zhou; Luwei Xu; Ruipeng Jia; Yu-Zheng Ge Journal: J Inflamm Res Date: 2022-02-16