title: Autophagy blockade sensitizes the anticancer activity of CA-4 via JNK-Bcl-2 pathway.
abstract: Combretastatin A-4 (CA-4) has already entered clinical trials of solid tumors over ten years. However, the limited anticancer activity and dose-dependent toxicity restrict its clinical application. Here, we offered convincing evidence that CA-4 induced autophagy in various cancer cells, which was demonstrated by acridine orange staining of intracellular acidic vesicles, the degradation of p62, the conversion of LC3-I to LC3-II and GFP-LC3 punctate fluorescence. Interestingly, CA-4-mediated apoptotic cell death was further potentiated by pretreatment with autophagy inhibitors (3-methyladenine and bafilomycin A1) or small interfering RNAs against the autophagic genes (Atg5 and Beclin 1). The enhanced anticancer activity of CA-4 and 3-MA was further confirmed in the SGC-7901 xenograft tumor model. These findings suggested that CA-4-elicited autophagic response played a protective role that impeded the eventual cell death while autophagy inhibition was expected to improve chemotherapeutic efficacy of CA-4. Meanwhile, CA-4 treatment led to phosphorylation/activation of JNK and JNK-dependent phosphorylation of Bcl-2. Importantly, JNK inhibitor or JNK siRNA inhibited autophagy but promoted CA-4-induced apoptosis, indicating a key requirement of JNK-Bcl-2 pathway in the activation of autophagy by CA-4. We also identified that pretreatment of Bcl-2 inhibitor (ABT-737) could significantly enhance anticancer activity of CA-4 due to inhibition of autophagy. Taken together, our data suggested that the JNK-Bcl-2 pathway was considered as the critical regulator of CA-4-induced protective autophagy and a potential drug target for chemotherapeutic combination.
authors: Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors: Yangling
authors: Y
authors: Li
authors: Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors: Peihua
authors: P
authors: Luo
authors: Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors: Jincheng
authors: J
authors: Wang
authors: Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors: Jiabin
authors: J
authors: Dai
authors: Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors: Xiaochun
authors: X
authors: Yang
authors: Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors: Honghai
authors: H
authors: Wu
authors: Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China. Electronic address: yang924@zju.edu.cn.
authors: Bo
authors: B
authors: Yang
authors: Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China. Electronic address: qiaojunhe@zju.edu.cn.
authors: Qiaojun
authors: Q
authors: He
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects*; D000071187:Autophagy-Related Protein 5; D000071186:Beclin-1; D001713:Biphenyl Compounds / Q000494:pharmacology; D045744:Cell Line, Tumor; D006801:Humans; D020935:MAP Kinase Signaling System; D018942:Macrolides / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D009596:Nitrophenols / Q000494:pharmacology; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D013267:Stilbenes / Q000494:pharmacology*; D013449:Sulfonamides / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
chemical_list: C501332:ABT-737; C502778:ATG5 protein, human; D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D000071187:Autophagy-Related Protein 5; C491997:BECN1 protein, human; D000071186:Beclin-1; D001713:Biphenyl Compounds; D018942:Macrolides; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D009596:Nitrophenols; D010879:Piperazines; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D013267:Stilbenes; D013449:Sulfonamides; C025946:3-methyladenine; C040929:bafilomycin A1; C058728:fosbretabulin; D000225:Adenine
keywords: ABT-737; Autophagy; Bcl-2; CA-4; JNK