title: Silibinin, a natural flavonoid, induces autophagy via ROS-dependent mitochondrial dysfunction and loss of ATP involving BNIP3 in human MCF7 breast cancer cells.
abstract: Silibinin, derived from the milk thistle plant (Silybum marianum), has anticancer and chemopreventive properties. Silibinin has been reported to inhibit the growth of various types of cancer cells. However, the mechanisms by which silibinin exerts an anticancer effect are poorly defined. The present study aimed to investigate whether silibinin-induced cell death might be attributed to autophagy and the underlying mechanisms in human MCF7 breast cancer cells. Our results showed that silibinin-induced cell death was greatly abrogated by two specific autophagy inhibitors, 3-methyladenine (3-MA) and bafilomycin-A1 (Baf-A1). In addition, silibinin triggered the conversion of light chain 3 (LC3)-I to LC3-II, promoted the upregulation of Atg12-Atg5 formation, increased Beclin-1 expression, and decreased the Bcl-2 level. Moreover, we noted elevated reactive oxygen species (ROS) generation, concomitant with the dissipation of mitochondrial transmembrane potential (ΔΨm) and a drastic decline in ATP levels following silibinin treatment, which were effectively prevented by the antioxidants, N-acetylcysteine and ascorbic acid. Silibinin stimulated the expression of Bcl-2 adenovirus E1B 19-kDa-interacting protein 3 (BNIP3), a pro-death Bcl-2 family member, and silencing of BNIP3 greatly inhibited silibinin-induced cell death, decreased ROS production, and sustained ΔΨm and ATP levels. Taken together, these findings revealed that silibinin induced autophagic cell death through ROS-dependent mitochondrial dysfunction and ATP depletion involving BNIP3 in MCF7 cells.
authors.affiliation: Department of Clinical Laboratory, Tongde Hospital of Zhejiang Province, Hangzhou, Zhejiang 310012, P.R. China.
authors.forename: Kai
authors.initials: K
authors.lastname: Jiang
authors.affiliation: Department of Clinical Laboratory, Tongde Hospital of Zhejiang Province, Hangzhou, Zhejiang 310012, P.R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Clinical Laboratory, Tongde Hospital of Zhejiang Province, Hangzhou, Zhejiang 310012, P.R. China.
authors.forename: Xin
authors.initials: X
authors.lastname: Jin
authors.affiliation: Department of Ophthalmology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, P.R. China.
authors.forename: Zhaoyang
authors.initials: Z
authors.lastname: Wang
authors.affiliation: School of Electronics and Information Engineering, Tongji University, Shanghai 201804, P.R. China.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Ji
authors.affiliation: Department of Clinical Laboratory, Tongde Hospital of Zhejiang Province, Hangzhou, Zhejiang 310012, P.R. China.
authors.forename: Guanmin
authors.initials: G
authors.lastname: Meng
mesh_terms: D000255:Adenosine Triphosphate / Q000235:genetics; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis / Q000235:genetics; D001343:Autophagy / Q000187:drug effects; D000071186:Beclin-1; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D005260:Female; D005419:Flavonoids / Q000008:administration & dosage*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D061986:MCF-7 Cells; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D008928:Mitochondria / Q000235:genetics / Q000473:pathology; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D000077385:Silybin; D012838:Silymarin / Q000008:administration & dosage*
chemical_list: D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; C090121:BNIP3 protein, human; D000071186:Beclin-1; D005419:Flavonoids; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D017382:Reactive Oxygen Species; D012838:Silymarin; D000077385:Silybin; D000255:Adenosine Triphosphate