Department of Orthopedic Surgery, Nihon University School of Medicine, Tokyo 173-8610, Japan.
Plasma ChemiBio Laboratory, Nasushiobara, Tochigi 329-2813, Japan.
Int J Oncol. 2017 Jul;51(1):193-203. doi: 10.3892/ijo.2017.4020. Epub 2017 May 25.
Ca2+ has emerged as a new target for cancer treatment since tumor-specific traits in Ca2+ dynamics contributes to tumorigenesis, malignant phenotypes, drug resistance, and survival in different tumor types. However, Ca2+ has a dual (pro-death and pro-survival) function in tumor cells depending on the experimental conditions. Therefore, it is necessary to minimize the onset of the pro-survival Ca2+ signals caused by the therapy. For this purpose, a better understanding of pro-survival Ca2+ pathways in cancer cells is critical. Here we report that Ca2+ protects malignant melanoma (MM) and osteosarcoma (OS) cells from tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) cytotoxicity. Simultaneous measurements using the site-specific Ca2+ probes showed that acute TRAIL treatment rapidly and dose-dependently increased the cytosolic Ca2+ concentration ([Ca2+]cyt) and mitochondrial Ca2+ concentration ([Ca2+]mit) Pharmacological analyses revealed that the [Ca2+]mit remodeling was under control of mitochondrial Ca2+ uniporter (MCU), mitochondrial permeability transition pore (MPTP), and a Ca2+ transport pathway sensitive to capsazepine and AMG9810. Ca2+ chelators and the MCU inhibitor ruthenium 360, an MPTP opener atractyloside, capsazepine, and AMG9810 all decreased [Ca2+]mit and sensitized these tumor cells to TRAIL cytotoxicity. The Ca2+ modulation enhanced both apoptotic and non-apoptotic cell death. Although the [Ca2+]mit reduction potentiated TRAIL-induced caspase-3/7 activation and cell membrane damage within 24 h, this potentiation of cell death became pronounced at 72 h, and not blocked by caspase inhibition. Our findings suggest that in MM and OS cells mitochondrial Ca2+ removal can promote apoptosis and non-apoptotic cell death induction by TRAIL. Therefore, mitochondrial Ca2+ removal can be exploited to overcome the resistance of these cancers to TRAIL.
钙离子已成为癌症治疗的新靶点，因为肿瘤特异性钙离子动力学特征有助于不同肿瘤类型的肿瘤发生、恶性表型、耐药性和存活。然而，钙离子在肿瘤细胞中具有双重（促死亡和促存活）功能，这取决于实验条件。因此，有必要最大限度地减少治疗引起的促存活钙离子信号的发生。为此，更好地了解肿瘤细胞中的促存活钙离子途径至关重要。在这里，我们报告钙离子可保护恶性黑色素瘤 (MM) 和骨肉瘤 (OS) 细胞免受肿瘤坏死因子 (TNF) 相关凋亡诱导配体 (TRAIL) 的细胞毒性。使用特异性钙离子探针的同时测量表明，急性 TRAIL 处理可快速且剂量依赖性地增加细胞质钙离子浓度 ([Ca2+]cyt) 和线粒体钙离子浓度 ([Ca2+]mit)。药理分析表明，[Ca2+]mit 重塑受线粒体钙离子单向转运体 (MCU)、线粒体通透性转换孔 (MPTP) 和一种对辣椒素和 AMG9810 敏感的钙离子转运途径的控制。钙离子螯合剂和 MCU 抑制剂钌 360、MPTP 开放剂长春碱、辣椒素和 AMG9810 均降低了 [Ca2+]mit，并使这些肿瘤细胞对 TRAIL 细胞毒性敏感。钙离子调节增强了凋亡和非凋亡细胞死亡。尽管 [Ca2+]mit 的减少增强了 TRAIL 诱导的 caspase-3/7 激活和细胞膜损伤在 24 小时内，但这种细胞死亡的增强在 72 小时时变得明显，并且不受 caspase 抑制的阻断。我们的研究结果表明，在 MM 和 OS 细胞中，线粒体钙离子去除可通过 TRAIL 促进细胞凋亡和非凋亡细胞死亡的诱导。因此，线粒体钙离子去除可用于克服这些癌症对 TRAIL 的耐药性。
