title: RUNX3 is involved in caspase-3-dependent apoptosis induced by a combination of 5-aza-CdR and TSA in leukaemia cell lines.
abstract: OBJECTIVE
  Epigenetic therapy has had a significant impact on the management of haematologic malignancies. The aim of this study was to assess whether 5-aza-CdR and TSA inhibit the growth of leukaemia cells and induce caspase-3-dependent apoptosis by upregulating RUNX3 expression.
  
  
  METHODS
  K562 and Reh cells were treated with 5-aza-CdR, TSA or both compounds. RT-PCR and Western blot analyses were used to examine the expression of RUNX3 at the mRNA and protein levels, respectively. Immunofluorescence microscopy was used to detect the cellular location of RUNX3. Additionally, after K562 cells were transfected with RUNX3, apoptosis and proliferation were studied using Annexin V staining and MTT assays.
  
  
  RESULTS
  The expression of RUNX3 in leukaemia cell lines was markedly less than that in the controls. Demethylating drug 5-aza-CdR could induce RUNX3 expression, but the combination of TSA and 5-aza-CdR had a greater effect than did treatment with a single compound. The combination of 5-aza-CdR and TSA induced the translocation of RUNX3 from the cytoplasm into the nucleus. TSA enhanced apoptosis induced by 5-aza-CdR, and Annexin V and Hoechst 33258 staining showed that the combination induced apoptosis but not necrosis. Furthermore, apoptosis was dependent on the caspase-3 pathway. RUNX3 overexpression in K562 cells led to growth inhibition and apoptosis and potentiated the effects of 5-aza-CdR induction.
  
  
  CONCLUSIONS
  RUNX3 plays an important role in leukaemia cellular functions, and the induction of RUNX3-mediated effects may contribute to the therapeutic value of combination TSA and 5-aza-CdR treatment.
authors.affiliation: Department of Hematology, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510630, China.
authors.forename: Feng-Xian
authors.initials: FX
authors.lastname: Zhai
authors.forename: Xiang-Fu
authors.initials: XF
authors.lastname: Liu
authors.forename: Rui-Fang
authors.initials: RF
authors.lastname: Fan
authors.forename: Zi-Jie
authors.initials: ZJ
authors.lastname: Long
authors.forename: Zhi-Gang
authors.initials: ZG
authors.lastname: Fang
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.forename: Yong-Jiang
authors.initials: YJ
authors.lastname: Zheng
authors.forename: Dong-Jun
authors.initials: DJ
authors.lastname: Lin
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001374:Azacitidine / Q000008:administration & dosage; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D050677:Core Binding Factor Alpha 3 Subunit / Q000378:metabolism*; D018899:CpG Islands; D005455:Fluorescent Antibody Technique; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D006877:Hydroxamic Acids / Q000008:administration & dosage; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
chemical_list: D050677:Core Binding Factor Alpha 3 Subunit; D006877:Hydroxamic Acids; C493729:Runx3 protein, human; C012589:trichostatin A; D053148:Caspase 3; D001374:Azacitidine