title: Retinoic acid receptor-β gene reexpression and biological activity in SHI-1 cells after combined treatment with 5-aza-2'-deoxycytidine and all-trans retinoic acid.
abstract: BACKGROUND
  This study was conducted to determine the antineoplastic activities of 5-aza-2'-deoxycytidine (decitabine; DAC) and all-trans retinoic acid (ATRA), administered either alone or in combination, on in vitro cultured SHI-1 cells as well as their effects on the expression of the tumor suppressor gene p16(INK4a) (p16) and the retinoic acid receptor (RAR)-β.
  
  
  METHODS
  Cell growth inhibition, differentiation and apoptosis were determined in SHI-1 cells treated with DAC and/or ATRA, and the combination index of the two compounds was calculated. Methylation of the p16 and RAR-β genes in SHI-1 cells was detected by methylation-specific polymerase chain reaction (PCR). Real-time quantitative reverse transcriptase PCR was used to detect mRNA expression of the p16 and RAR-β genes, and Western blot analysis was performed for protein expression.
  
  
  RESULTS
  The drug combination had a synergistic effect on growth inhibition, differentiation and apoptosis of SHI-1 cells, and the effects of DAC and ATRA were dependent on time. DAC, either alone or in combination with ATRA, induced demethylation of the genes p16 and RAR-β, whereas ATRA alone had no effect on methylation. The RAR-β gene was reexpressed following DAC-ATRA combination treatment, and both agents had no effect on p16 expression.
  
  
  CONCLUSIONS
  The results revealed that DAC used in combination with ATRA has significant clinical potential in the treatment of acute monocytic leukemia.
authors.affiliation: Department of Hematology, The First People's Hospital of Changzhou, Third Affiliated Hospital of Suzhou University, Changzhou, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Xiang
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.forename: Jiang
authors.initials: J
authors.lastname: Wei
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Qiu
authors.forename: Jiannong
authors.initials: J
authors.lastname: Cen
authors.forename: Shaoyan
authors.initials: S
authors.lastname: Hu
authors.forename: Xiaobao
authors.initials: X
authors.lastname: Xie
authors.forename: Zixing
authors.initials: Z
authors.lastname: Chen
authors.forename: Weiying
authors.initials: W
authors.lastname: Gu
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001374:Azacitidine / Q000819:agonists / Q000031:analogs & derivatives / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects*; D045744:Cell Line, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism; D000077209:Decitabine; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D007948:Leukemia, Monocytic, Acute / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D018168:Receptors, Retinoic Acid / Q000096:biosynthesis*; D014212:Tretinoin / Q000819:agonists / Q000494:pharmacology
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; D018168:Receptors, Retinoic Acid; C082925:retinoic acid receptor beta; D014212:Tretinoin; D000077209:Decitabine; D001374:Azacitidine