title: [siRNA silences mdr1 gene expression and reverses apoptosis resistance of K562/ADM cells line].
abstract: OBJECTIVE
  To explore the effect of small interfering RNA(siRNA) on silence of mdr1 gene and reversal of apoptosis resistance in multidrug-resistant (MDR) human leukemia K562/ADM cell.
  
  
  METHODS
  Human MDR leukemia cell line K562/ADM was used as the target cells. Two siRNAs (mdr1 siRNA-1 and mdr1 siRNA-2) targeted mdr1 gene were chemically synthesized and transfected into K562/ADM cells with liposome. Expression of mdr1 mRNA was determined by real-time PCR, P-glycoprotein (P-gp) expression and caspase-3 activity were measured with flow cytometry (FCM), and the cell apoptosis was observed by optical and electronic microscopy for morphology and Annexin V/PI staining.
  
  
  RESULTS
  The mdr1 siRNA-1 and mdr1 siRNA-2 could markedly down-regulate the expression of mdr1 gene in K562/ADM cells, the expression of mdr1 mRNA decreased by 91.2% and 82.0% , and the P-gp by 74.1% and 84.4%, respectively. The caspase-3 activity was markedly enhanced, and the active caspase-3 in K562/ADM cells increased by about 40% compared to liposome alone and non-silencing controls. the sensitivity of K562/ADM cells to adriamycin-induced apoptosis was significantly augmented, the apoptotic rate of the cells treated with siRNA plus adriamycin increased by about 60% compared to adriamycin alone.
  
  
  CONCLUSIONS
  siRNAs silence the expression of mdr1/P-gp to overcome the P-gp-mediated apoptosis resistance in drug-resistant K562/ADM cells.
authors.affiliation: Laboratory Center for Medical Science, Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Lanzhou University, Lanzhou 730000, China.
authors.forename: Hu-lai
authors.initials: HL
authors.lastname: Wei
authors.forename: Li-ping
authors.initials: LP
authors.lastname: Gao
authors.forename: Tao
authors.initials: T
authors.lastname: Jing
authors.forename: Huai-shun
authors.initials: HS
authors.lastname: Zhao
authors.forename: Juan
authors.initials: J
authors.lastname: Yi
authors.forename: Jin
authors.initials: J
authors.lastname: Sun
authors.forename: Jian
authors.initials: J
authors.lastname: Han
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D018432:Drug Resistance, Multiple / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D006801:Humans; D020014:K562 Cells; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics*; D014162:Transfection
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D053148:Caspase 3