title: Caspase-3 feedback loop enhances Bid-induced AIF/endoG and Bak activation in Bax and p53-independent manner.
abstract: Chemoresistance in cancer has previously been attributed to gene mutations or deficiencies. Bax or p53 deficiency can lead to resistance to cancer drugs. We aimed to find an agent to overcome chemoresistance induced by Bax or p53 deficiency. Here, we used immunoblot, flow-cytometry analysis, gene interference, etc. to show that genistein, a major component of isoflavone that is known to have anti-tumor activities in a variety of models, induces Bax/p53-independent cell death in HCT116 Bax knockout (KO), HCT116 p53 KO, DU145 Bax KO, or DU145 p53 KO cells that express wild-type (WT) Bak. Bak knockdown (KD) only partially attenuated genistein-induced apoptosis. Further results indicated that the release of AIF and endoG also contributes to genistein-induced cell death, which is independent of Bak activation. Conversely, AIF and endoG knockdown had little effect on Bak activation. Knockdown of either AIF or endoG alone could not efficiently inhibit apoptosis in cells treated with genistein, whereas an AIF, endoG, and Bak triple knockdown almost completely attenuated apoptosis. Next, we found that the Akt-Bid pathway mediates Bak-induced caspase-dependent and AIF- and endoG-induced caspase-independent cell death. Moreover, downstream caspase-3 could enhance the release of AIF and endoG as well as Bak activation via a positive feedback loop. Taken together, our data elaborate the detailed mechanisms of genistein in Bax/p53-independent apoptosis and indicate that caspase-3-enhanced Bid activation initiates the cell death pathway. Our results also suggest that genistein may be an effective agent for overcoming chemoresistance in cancers with dysfunctional Bax and p53.
authors.affiliation: Department of Abdominal Oncology, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, 17# People's South Road, Chengdu, Chengdu 610041, PR China.
authors.forename: W
authors.initials: W
authors.lastname: Guo
authors.affiliation: Departmant of Oncology, Guizhou People's Hospital, Guizhou 550002, PR China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Departmant of Oncology, The Fourth People's Hospital of Sichuan province, Chengdu 610041, PR China.
authors.forename: Z
authors.initials: Z
authors.lastname: Ling
authors.affiliation: Department of Abdominal Oncology, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, 17# People's South Road, Chengdu, Chengdu 610041, PR China.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Abdominal Oncology, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, 17# People's South Road, Chengdu, Chengdu 610041, PR China.
authors.forename: X
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Department of Abdominal Oncology, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, 17# People's South Road, Chengdu, Chengdu 610041, PR China.
authors.forename: Z
authors.initials: Z
authors.lastname: Yuan
authors.affiliation: Department of Abdominal Oncology, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, 17# People's South Road, Chengdu, Chengdu 610041, PR China.
authors.forename: C
authors.initials: C
authors.lastname: Nie
authors.affiliation: Department of Abdominal Oncology, State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, 17# People's South Road, Chengdu, Chengdu 610041, PR China.
authors.forename: Y
authors.initials: Y
authors.lastname: Wei
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D051033:Apoptosis Inducing Factor / Q000378:metabolism*; D051023:BH3 Interacting Domain Death Agonist Protein / Q000502:physiology*; D053148:Caspase 3 / Q000502:physiology*; D045744:Cell Line, Tumor; D004706:Endodeoxyribonucleases / Q000502:physiology*; D025461:Feedback, Physiological; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
chemical_list: C494829:AIFM1 protein, human; D051033:Apoptosis Inducing Factor; C494772:BAK1 protein, human; C494826:BAX protein, human; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D019833:Genistein; D051057:Proto-Oncogene Proteins c-akt; D004706:Endodeoxyribonucleases; C052391:endonuclease G; C505407:CASP3 protein, human; D053148:Caspase 3