title: Silencing HO-1 sensitizes SKM-1 cells to apoptosis induced by low concentration 5-azacytidine through enhancing p16 demethylation.
abstract: Heme oxygenase-1 was reported previously as a resistance target on acute myelocytic leukemia (AML). We found that HO-1 was resistant to 5-azacytidine (AZA) treatment of myelodysplastic syndrome (MDS), and explored further the relative mechanisms. Patient bone marrow mononuclear cells (n=48) diagnosed as different levels of MDS were collected. Cell growth was evaluated by MTT assay; cell cycle and apoptosis were detected by flow cytometry; mRNA expression was assessed by real-time PCR, protein expression was analyzed through western blotting. Methylation was assessed by MSP. The survival time, and weight of mice were recorded. HO-1 overexpression was observed in SKM-1 cells after AZA treatment comparing to other cell lines. The HO-1 expression in MDS patients with high-risk was higher than in low-risk patients. After HO-1 was silenced by lentivirus-mediated siRNA, the proliferation of SKM-1 cells was effectively inhibited by low concentration AZA, and the cell cycle was arrested in the G0/G1 phase. Upregulation of p16 and changing of p16-relative cell cycle protein was observed after silencing HO-1 in AZA treated SKM-1 cells. In addition, DNMT1 was downregulated following the decrease of HO-1 expression. In vivo, silencing HO-1 inhibited SKM-1 cell growth induced by AZA in a NOD/SCID mouse model. Silencing HO-1 sensitized SKM-1 cells toward AZA, which may be attributed to the influence of HO-1 on AZA-induced p16 demethylation. HO-1 may be one of the targets that enhance the therapeutic effects of AZA on MDS malignant transformation inspiring new treatment methods for high-risk and very high-risk MDS patients in clinical practice.
authors.affiliation: Department of Hematology, Affiliated Hospital of Guiyang Medical University, Guiyang 550004, P.R. China.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Hematology, Affiliated Hospital of Guiyang Medical University, Guiyang 550004, P.R. China.
authors.forename: Dan
authors.initials: D
authors.lastname: Ma
authors.affiliation: Department of Hematology, Affiliated Hospital of Guiyang Medical University, Guiyang 550004, P.R. China.
authors.forename: Jishi
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Pharmacy, Affiliated Baiyun Hospital of Guiyang Medical University, Guiyang 550014, P.R. China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Fang
authors.affiliation: Department of Hematology, Affiliated Hospital of Guiyang Medical University, Guiyang 550004, P.R. China.
authors.forename: Rui
authors.initials: R
authors.lastname: Gao
authors.affiliation: Department of Hematology, Affiliated Hospital of Guiyang Medical University, Guiyang 550004, P.R. China.
authors.forename: Weibing
authors.initials: W
authors.lastname: Wu
authors.affiliation: School of Pharmacy, Guiyang Medical University, Guiyang 550004, P.R. China.
authors.forename: Tangsheng
authors.initials: T
authors.lastname: Lu
authors.affiliation: School of Pharmacy, Guiyang Medical University, Guiyang 550004, P.R. China.
authors.forename: Lu
authors.initials: L
authors.lastname: Cao
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D001374:Azacitidine / Q000008:administration & dosage / Q000494:pharmacology*; D002478:Cells, Cultured; D019175:DNA Methylation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000235:genetics; D005260:Female; D020868:Gene Silencing / Q000502:physiology; D019942:Genes, p16 / Q000187:drug effects; D057809:HEK293 Cells; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000235:genetics*; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008875:Middle Aged; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000494:pharmacology*; D020298:U937 Cells; D023041:Xenograft Model Antitumor Assays
chemical_list: D034741:RNA, Small Interfering; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1; D001374:Azacitidine