一种新型铂（PT）配合物通过改变氧化还原平衡和调节 MAPK 通路诱导结直肠癌细胞死亡。
A novel coordination complex of platinum (PT) induces cell death in colorectal cancer by altering redox balance and modulating MAPK pathway.
机构信息
Colorectal Research Chair, Department of Surgery, King Saud University College of Medicine, PO Box 7805 (37), Riyadh, 11472, Saudi Arabia.
College of Medicine Research Center, King Saud University College of Medicine, Riyadh, 11472, Saudi Arabia.
出版信息
BMC Cancer. 2020 Jul 23;20(1):685. doi: 10.1186/s12885-020-07165-w.
BACKGROUND
Colorectal cancer (CRC) is a heterogeneous tumor having various genetic alterations. The current treatment options had limited impact on disease free survival due to therapeutic resistance. Novel anticancer agents are needed to treat CRC specifically metastatic colorectal cancer. A novel coordination complex of platinum, (salicylaldiminato)Pt(II) complex with dimethylpropylene linkage (PT) exhibited potential anti-cancer activity. In this study, we explored the molecular mechanism of PT-induced cell death in colorectal cancer.
METHODS
Colony formation was evaluated using the clonogenic assay. Apoptosis, cell cycle analysis, reactive oxygen species, mitochondrial membrane potential and caspase-3/- 7 were assessed by flow cytometry. Glutathione level was detected by colorimetric assay. PT-induced alteration in pro-apoptotic/ anti-apoptotic proteins and other signaling pathways were investigated using western blotting. P38 downregulation was performed using siRNA.
RESULTS
In the present study, we explored the molecular mechanism of PT-mediated inhibition of cell proliferation in colorectal cancer cells. PT significantly inhibited the colony formation in human colorectal cancer cell lines (HT-29, SW480 and SW620) by inducing apoptosis and necrosis. This platinum complex was shown to significantly increase the reactive oxygen species (ROS) generation, depletion of glutathione and reduced mitochondrial membrane potential in colorectal cancer cells. Exposure to PT resulted in the downregulation of anti-apoptotic proteins (Bcl2, BclxL, XIAP) and alteration in Cyclins expression. Furthermore, PT increased cytochrome c release into cytosol and enhanced PARP cleavage leading to activation of intrinsic apoptotic pathway. Moreover, pre-treatment with ROS scavenger N-acetylcysteine (NAC) attenuated apoptosis suggesting that PT-induced apoptosis was driven by oxidative stress. Additionally, we show that PT-induced apoptosis was mediated by activating p38 MAPK and inhibiting AKT pathways. This was demonstrated by using chemical inhibitor and siRNA against p38 kinase which blocked the cytochrome c release and apoptosis in colorectal cancer cells.
CONCLUSION
Collectively, our data demonstrates that the platinum complex (PT) exerts its anti-proliferative effect on CRC by ROS-mediated apoptosis and activating p38 MAPK pathway. Thus, our findings reveal a novel mechanism of action for PT on colorectal cancer cells and may have therapeutic implication.
背景
结直肠癌（CRC）是一种具有多种遗传改变的异质性肿瘤。由于治疗耐药性，目前的治疗选择对无病生存的影响有限。需要新型抗癌药物来专门治疗结直肠癌，特别是转移性结直肠癌。一种新型铂配合物，（水杨醛亚胺）Pt（II）配合物与二甲基丙烯基连接（PT），表现出潜在的抗癌活性。在这项研究中，我们探讨了 PT 诱导结直肠癌细胞死亡的分子机制。
方法
使用集落形成实验评估集落形成。通过流式细胞术评估细胞凋亡、细胞周期分析、活性氧（ROS）、线粒体膜电位和 caspase-3/-7。通过比色法检测谷胱甘肽水平。使用 Western blot 研究 PT 诱导的促凋亡/抗凋亡蛋白和其他信号通路的改变。使用 siRNA 下调 p38。
结果
在本研究中，我们探讨了 PT 介导的抑制结直肠癌细胞增殖的分子机制。PT 通过诱导细胞凋亡和坏死，显著抑制人结直肠癌细胞系（HT-29、SW480 和 SW620）的集落形成。该铂配合物可显著增加结直肠癌细胞中的活性氧（ROS）生成、谷胱甘肽耗竭和线粒体膜电位降低。暴露于 PT 导致抗凋亡蛋白（Bcl2、BclxL、XIAP）下调和细胞周期蛋白表达改变。此外，PT 增加细胞色素 c 向细胞质中的释放，并增强 PARP 切割，导致内在凋亡途径的激活。此外，用 ROS 清除剂 N-乙酰半胱氨酸（NAC）预处理可减轻凋亡，表明 PT 诱导的凋亡是由氧化应激驱动的。此外，我们表明 PT 诱导的凋亡是通过激活 p38 MAPK 和抑制 AKT 途径介导的。这是通过使用化学抑制剂和针对 p38 激酶的 siRNA 来实现的，该抑制剂阻断了结直肠癌细胞中的细胞色素 c 释放和凋亡。
结论
总之，我们的数据表明，铂配合物（PT）通过 ROS 介导的凋亡和激活 p38 MAPK 途径发挥其对 CRC 的抗增殖作用。因此，我们的发现揭示了 PT 对结直肠癌细胞的新作用机制，并可能具有治疗意义。
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