Saleem Muhammad Zubair, Alshwmi Mohammed, Zhang He, Din Syed Riaz Ud, Nisar Muhammad Azhar, Khan Muhammad, Alam Shahid, Alam Gulzar, Jin Lingling, Ma Tonghui
College of Basic Medical Sciences, Dalian Medical University, Dalian, China.
Department of Clinical Laboratory, The First Affiliated Hospital of Dalian Medical University, Dalian Medical University, Dalian, China.
Front Pharmacol. 2020 Sep 4;11:01055. doi: 10.3389/fphar.2020.01055. eCollection 2020.
Breast cancer is the most heterogenous cancer type among women across the world. Despite concerted efforts, breast cancer management is still unsatisfactory. Interplay between apoptosis and autophagy is an imperative factor in categorizing therapeutics for cancer treatment. Proscillaridin A (PSD-A), a well-known cardiac glycoside used for cardiac arrest and arrythmias, has been unveiled in many cancer types but the underlying mechanism for apoptosis and autophagy in breast cancer is not fully understood. In our study, PSD-A restricted cell growth, inhibited STAT3 activation and induced apoptosis and autophagy in breast cancer cells ROS generation and Ca oscillation. Pretreatment of NAC and BAPTA-AM restored PSD-A induced cellular events in breast cancer cells. PSD-A induced apoptosis DNA fragmentation, caspase-cascade activation, PARP cleavage, mitochondrial dysfunction, Bax/Bcl-2 proteins modulation and ER chaperone GRP78 inhibition along with decreased phosphorylation of ERK1/2. Inhibition of STAT3 activation was found to be associated with decreased phosphorylation of SRC. Moreover, PSD-A induced events of autophagy i.e. conversion of LC3-I to LC3-II, and Atg3 expression JNK activation and decreased mTOR and AKT phosphorylation. In this study, pretreatment of SP600125, a JNK inhibitor, reduced autophagy and enhanced STAT3 inhibition and apoptosis. Additionally, SB203580, a commercial p38 inhibitor, stimulated STAT3 activation and improved autophagic events rate in breast cancer cells, displaying the role of the MAPK signaling pathway in interplay between apoptosis and autophagy. Our data suggest that the rate of apoptotic cell death is improved by blocking JNK-induced autophagy in PSD-A treated MCF-7 and MDA-MB-231 breast cancer cells.
乳腺癌是全球女性中异质性最强的癌症类型。尽管各方共同努力，但乳腺癌的治疗效果仍不尽人意。细胞凋亡与自噬之间的相互作用是癌症治疗药物分类的一个重要因素。海葱苷A（PSD-A）是一种用于治疗心脏骤停和心律失常的著名强心苷，已在多种癌症类型中被发现，但其在乳腺癌中诱导细胞凋亡和自噬的潜在机制尚未完全明确。在我们的研究中，PSD-A可抑制乳腺癌细胞的生长，抑制信号转导和转录激活因子3（STAT3）的激活，并诱导细胞凋亡和自噬，同时伴有活性氧（ROS）生成和钙振荡。用N-乙酰半胱氨酸（NAC）和1,2-双（2-氨基苯氧基）乙烷-N,N,N',N'-四乙酸四乙酰甲酯（BAPTA-AM）预处理可恢复PSD-A诱导的乳腺癌细胞中的细胞事件。PSD-A诱导细胞凋亡，表现为DNA片段化、半胱天冬酶级联激活、聚（ADP-核糖）聚合酶（PARP）裂解、线粒体功能障碍、Bax/Bcl-2蛋白调节以及内质网伴侣葡萄糖调节蛋白78（GRP78）抑制，同时细胞外信号调节激酶1/2（ERK1/2）的磷酸化水平降低。发现抑制STAT3激活与Src磷酸化水平降低有关。此外，PSD-A诱导自噬事件，即微管相关蛋白1轻链3（LC3）-I向LC3-II的转化以及自噬相关蛋白3（Atg3）的表达，同时伴有应激活化蛋白激酶（JNK）激活以及雷帕霉素靶蛋白（mTOR）和蛋白激酶B（AKT）磷酸化水平降低。在本研究中，用JNK抑制剂SP600125预处理可减少自噬，并增强对STAT3的抑制作用和细胞凋亡。此外，商业p38抑制剂SB203580可刺激STAT3激活，并提高乳腺癌细胞中的自噬事件发生率，显示出丝裂原活化蛋白激酶（MAPK）信号通路在细胞凋亡与自噬相互作用中的作用。我们的数据表明，在PSD-A处理的MCF-7和MDA-MB-231乳腺癌细胞中，通过阻断JNK诱导的自噬可提高细胞凋亡率。
