title: Silencing of myeloid cell leukemia-1 by small interfering RNA improves chemosensitivity to etoposide in u-937 leukemic cells.
abstract: A key issue in the treatment of acute myeloid leukemia (AML) is the development of drug resistance to chemotherapeutic agents. Overexpression of myeloid cell leukemia-1 (Mcl-1), an anti-apoptotic protein, is associated with tumor progression and drug resistance in leukemia and several cancers. The purpose of this study was to investigate the effect of specific Mcl-1 small interference RNA (siRNA) on the proliferation and chemosensitivity of U-937 AML cell to etoposide. The siRNA transfection was conducted using Lipofectamine 2000. Quantitative real-time RT-PCR (qRT-PCR) and Western blot analysis were employed to measure the expression levels of mRNA and protein, respectively. To evaluate tumor cell growth after siRNA transfection, Trypan blue exclusion assay was conducted. The cytotoxic effects of siRNA and etoposide were determined using MTT assay on their own and in combination. DNA-histone ELISA and annexin-V/FITC assays were performed to study the apoptosis. Mcl-1 siRNA transfection significantly blocked the expression of Mcl-1 mRNA and protein in a time-dependent manner, leading to a strong growth inhibition and enhanced apoptosis (P less than 0.05). Furthermore, pretreatment with Mcl-1 siRNA, synergistically enhanced the cytotoxic and apoptotic effects of etoposide (P less than 0.05). Our results demonstrated that Mcl-1 plays a fundamental role in the survival and resistance of U-937 cells to etoposide. Therefore, Mcl-1 can be considered an attractive target in gene therapy of AML patients and siRNA-mediated silencing of this gene may be a novel strategy in AML treatment.
authors.affiliation: Department of Human Anatomy, Faculty of Medicine and Health sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.
authors.forename: M
authors.initials: M
authors.lastname: Jafarlou
authors.affiliation: Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: B
authors.initials: B
authors.lastname: Baradaran
authors.affiliation: Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: D
authors.initials: D
authors.lastname: Shanehbandi
authors.affiliation: Institute of Biosciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.
authors.forename: T A
authors.initials: TA
authors.lastname: Saedi
authors.affiliation: Department of Surgery, Imam Reza Hospital, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: V
authors.initials: V
authors.lastname: Jafarlou
authors.affiliation: Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: P
authors.initials: P
authors.lastname: Karimi
authors.affiliation: Department of Human Anatomy, Faculty of Medicine and Health sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.
authors.forename: F
authors.initials: F
authors.lastname: Othman
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D004347:Drug Interactions; D004357:Drug Synergism; D005047:Etoposide / Q000494:pharmacology*; D005434:Flow Cytometry; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects*; D006801:Humans; D020128:Inhibitory Concentration 50; D007938:Leukemia / Q000235:genetics* / Q000473:pathology; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism*; D014162:Transfection; D020298:U937 Cells
chemical_list: C579095:MCL1 protein, human; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D005047:Etoposide