Al-Bahlani Shadia M, Al-Bulushi Khadija H, Al-Alawi Zaina M, Al-Abri Nadia Y, Al-Hadidi Zuweina R, Al-Rawahi Shaikha S
Department of Allied Health Sciences, College of Medicine and Health Sciences, Sultan Qaboos University, Al Khoud, Sultanate of Oman.
Department of Pathology, College of Medicine and Health Sciences, Sultan Qaboos University, Al Khoud, Sultanate of Oman.
Clin Breast Cancer. 2017 Jun;17(3):e103-e112. doi: 10.1016/j.clbc.2016.12.001. Epub 2016 Dec 24.
Breast cancer is the most common cancer in women worldwide. Triple-negative breast cancer (TNBC) is an aggressive type that can be treated using platinum-based chemotherapy such as cisplatin (cis-diamminedichloroplatinum II). Although the calpain protein is essential in many cellular processes, including apoptosis, cell signaling, and proliferation, its role in cisplatin-induced apoptosis in TNBC cells is not fully understood. The present study assessed calpain 1-dependent, cisplatin-induced apoptosis in TNBC cells.
MDA-MB231 cells were treated with different concentrations of cisplatin (0, 20, and 40 μM). The cisplatin deposit and its effect on endoplasmic reticulum and, subsequently, calcium release were detected using transmission electron microscopy and Von Koss staining, respectively. Calpain 1 messenger RNA, protein content, and apoptosis was measured using reverse transcriptase-polymerase chain reaction, Western blotting, and Hoechst stain, respectively. In addition, calpain modulation, by either activation or inhibition, and its effect on cisplatin-induced apoptosis were assessed.
Our results showed that cisplatin induced endoplasmic reticulum stress, indicated by an increase in calcium staining and protein expression of glucose-regulated protein 78 and calmodulin, followed by cleavage of α-fodrin and caspase-12 and, eventually, apoptosis. Cyclopiazonic acid showed a similar effect and enhanced the sensitivity of these cells to cisplatin treatment. In contrast, calpain 1 inhibition by both specific small interfering RNA and exogenous inhibitor (calpeptin) attenuated cisplatin-induced apoptosis in these cells.
Altogether, these findings suggest, for the first time, that calpain 1 activation by endoplasmic reticulum plays an essential role in sensitizing TNBC cells to cisplatin-induced apoptosis. This finding will allow exploration of new insights for the treatment of TNBC by overcoming its resistance to apoptosis.
乳腺癌是全球女性中最常见的癌症。三阴性乳腺癌（TNBC）是一种侵袭性类型，可用顺铂（顺二氯二氨合铂II）等铂类化疗药物治疗。尽管钙蛋白酶在许多细胞过程中至关重要，包括细胞凋亡、细胞信号传导和增殖，但其在TNBC细胞中顺铂诱导的细胞凋亡中的作用尚未完全明确。本研究评估了钙蛋白酶1依赖性顺铂诱导的TNBC细胞凋亡。
用不同浓度的顺铂（0、20和40μM）处理MDA-MB231细胞。分别使用透射电子显微镜和冯·科萨染色检测顺铂沉积及其对内质网的影响以及随后的钙释放。分别使用逆转录聚合酶链反应、蛋白质印迹法和Hoechst染色测量钙蛋白酶1信使核糖核酸、蛋白质含量和细胞凋亡。此外，评估了通过激活或抑制对钙蛋白酶的调节及其对顺铂诱导的细胞凋亡的影响。
我们的结果表明，顺铂诱导内质网应激，表现为钙染色增加以及葡萄糖调节蛋白78和钙调蛋白的蛋白质表达增加，随后α-血影蛋白和半胱天冬酶-12裂解，最终导致细胞凋亡。环匹阿尼酸显示出类似的效果，并增强了这些细胞对顺铂治疗的敏感性。相反，特异性小干扰RNA和外源性抑制剂（钙肽素）对钙蛋白酶1的抑制减弱了这些细胞中顺铂诱导的细胞凋亡。
总之，这些发现首次表明内质网对钙蛋白酶1的激活在使TNBC细胞对顺铂诱导的细胞凋亡敏感化方面起着至关重要的作用。这一发现将为克服TNBC对细胞凋亡的抗性探索新的治疗思路。
