title: The targeted inhibition of mitochondrial Hsp90 overcomes the apoptosis resistance conferred by Bcl-2 in Hep3B cells via necroptosis.
abstract: Previous studies have reported that a Gamitrinib variant containing triphenylphosphonium (G-TPP) binds to mitochondrial Hsp90 and rapidly inhibits its activity, thus inducing the apoptotic pathway in the cells. Accordingly, G-TPP shows a potential as a promising drug for the treatment of cancer. A cell can die from different types of cell death such as apoptosis, necrosis, necroptosis, and autophagic cell death. In this study, we further investigated the mechanisms and modes of cell death in the G-TPP-treated Hep3B and U937 cell lines. We discovered that G-TPP kills the U937 cells through the apoptotic pathway and the overexpression of Bcl-2 significantly inhibits U937 cell death to G-TPP. We further discovered that G-TPP kills the Hep3B cells by activating necroptosis in combination with the partial activation of caspase-dependent apoptosis. Importantly, G-TPP overcomes the apoptosis resistance conferred by Bcl-2 in Hep3B cells via necroptosis. We also observed that G-TPP induces compensatory autophagy in the Hep3B cell line. We further found that whereas there is a Bcl-2-Beclin 1 interaction in response to G-TPP, silencing the beclin 1 gene failed to block LC3-II accumulation in the Hep3B cells, indicating that G-TPP triggers Beclin 1-independent protective autophagy in Hep3B cells. Taken together, these data reveal that G-TPP induces cell death through a combination of death pathways, including necroptosis and apoptosis, and overcomes the apoptosis resistance conferred by Bcl-2 in Hep3B cells via necroptosis. These findings are important for the therapeutic exploitation of necroptosis as an alternative cell death program to bypass the resistance to apoptosis.
authors.affiliation: Department of Anatomy and Cell Biology, Dong-A University College of Medicine and Mitochondria Hub Regulation Center, Busan, 602-714, South Korea.
authors.forename: Chunlan
authors.initials: C
authors.lastname: Yan
authors.forename: Joon Seok
authors.initials: JS
authors.lastname: Oh
authors.forename: Seung Hee
authors.initials: SH
authors.lastname: Yoo
authors.forename: Jee Suk
authors.initials: JS
authors.lastname: Lee
authors.forename: Young Geol
authors.initials: YG
authors.lastname: Yoon
authors.forename: Yoo Jin
authors.initials: YJ
authors.lastname: Oh
authors.forename: Min Seok
authors.initials: MS
authors.lastname: Jang
authors.forename: Sang Yeob
authors.initials: SY
authors.lastname: Lee
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.forename: Sang Hwa
authors.initials: SH
authors.lastname: Lee
authors.forename: Hye Young
authors.initials: HY
authors.lastname: Kim
authors.forename: Young Hyun
authors.initials: YH
authors.lastname: Yoo
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems / Q000379:methods; D006146:Guanidines / Q000008:administration & dosage* / Q000737:chemistry; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D006801:Humans; D047029:Lactams, Macrocyclic / Q000008:administration & dosage* / Q000737:chemistry; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009336:Necrosis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D020298:U937 Cells
chemical_list: D006146:Guanidines; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D019253:Proto-Oncogene Proteins c-bcl-2; C557898:gamitrinib-G4