Ouyang Hui, Zhou Enxiang, Wang Huan
Department of Breast and Thyroid Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China,
Onco Targets Ther. 2019 Feb 11;12:1147-1159. doi: 10.2147/OTT.S193787. eCollection 2019.
Mst1-Hippo pathway and mitochondrial fragmentation participate in the progression of several types of cancers. However, their roles in breast cancer requires investigation. The aim of our study is to determine whether Mst1 overexpression regulates the viability of breast cancer cells via modulating mitochondrial fragmentation.
TUNEL staining, MTT assay and Western blotting were used to detect cancer cell death. Adenovirus-loaded Mst1 was transfected into cells to overexpress Mst1. Mitochondrial fragmentation was observed via immunofluorescence staining and Western blotting. Pathway blocker was used to detect whether Mst1 modulated cell death and mitochondrial fragmentation via JNK signaling pathway.
Our data showed that Mst1 overexpression promoted breast cancer cell death in a manner dependent on mitochondrial apoptosis. Mitochondrial oxidative stress, energy metabolism disorder, mitochondrial cyt- liberation and mitochondrial apoptosis activation were observed after Mst1 overexpression. Furthermore, we demonstrated that Mst1 overexpression activated mitochondrial stress via triggering Drp1-related mitochondrial fragmentation, and that inhibition of Drp1-related mitochondrial fragmentation abrogated the proapoptotic effect of Mst1 overexpression on breast cancer cells. To this end, we found that Mst1 modulated Drp1 expression via the JNK signaling pathway, and that blockade of the JNK pathway attenuated mitochondrial stress and repressed apoptosis in Mst1-overexpressed cells.
Altogether, our results identified a tumor suppressive role for Mst1 overexpression in breast cancer via activation of the JNK-Drp1 axis and subsequent initiation of fatal mitochondrial fragmentation. Given these findings, strategies to enhance Mst1 activity and elevate the JNK-Drp1-mitochondrial fragmentation cascade have clinical benefits for patients with breast cancer.
Mst1-Hippo通路和线粒体碎片化参与多种癌症的进展。然而，它们在乳腺癌中的作用尚需研究。本研究的目的是确定Mst1过表达是否通过调节线粒体碎片化来调控乳腺癌细胞的活力。
采用TUNEL染色、MTT法和蛋白质免疫印迹法检测癌细胞死亡情况。将携带腺病毒的Mst1转染至细胞中以过表达Mst1。通过免疫荧光染色和蛋白质免疫印迹法观察线粒体碎片化情况。使用通路阻断剂检测Mst1是否通过JNK信号通路调节细胞死亡和线粒体碎片化。
我们的数据表明，Mst1过表达以依赖线粒体凋亡的方式促进乳腺癌细胞死亡。Mst1过表达后观察到线粒体氧化应激、能量代谢紊乱、线粒体细胞色素释放和线粒体凋亡激活。此外，我们证明Mst1过表达通过触发与Drp1相关的线粒体碎片化激活线粒体应激，并且抑制与Drp1相关的线粒体碎片化可消除Mst1过表达对乳腺癌细胞的促凋亡作用。为此，我们发现Mst1通过JNK信号通路调节Drp1表达，并且阻断JNK通路可减轻线粒体应激并抑制Mst1过表达细胞中的凋亡。
总之，我们的结果确定了Mst1过表达在乳腺癌中的肿瘤抑制作用，其通过激活JNK-Drp1轴并随后引发致命的线粒体碎片化来实现。鉴于这些发现，增强Mst1活性并提升JNK-Drp1-线粒体碎片化级联反应的策略对乳腺癌患者具有临床益处。
