title: [Reversal of multidrug resistance in leukemic cell line K562/AO2 by chlordelazine in vitro].
abstract: OBJECTIVE
  Some recent studies revealed that phenthiazine might be able to reverse tumor cell drug-resistance. Chlorderazin belongs to the phenthiazine compounds. The study aimed to investigate the reversing effect and mechanism of chlorderazin on multidrug resistance of leukemic cell line K562/AO2.
  
  
  METHODS
  (1) The cytotoxicities of chlorderazin were assayed with the tetrazolium dye, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. (2) The reverse effect of chlorderazin on K562/AO2 cells was analyzed with MTT method. The multidrug resistance reversal index (RI) was equal to the ratio of control group IC(50)/test group half inhibition concentration IC(50). (3) The intracellular daunorubicin (DNR) concentrations were measured by the flow cytometry. (4) Mdr1 mRNA expression was detected by reverse transcription-polymerase chain reaction (RT-PCR). The ratio of mdr-1/beta-actin density was calculated.
  
  
  RESULTS
  (1) Chlorderazin 3 micro g/ml showed little toxicity to K562/AO2 cells and the suppression rate was less than 5%, so the concentration of 3 micro g/ml chlorderazin was selected as the experiment concentration. (2) The cytotoxicities of DNR to K562/AO2 were enhanced by 3 micro g/ml of chlorderazin (P < 0.05) and RI was 1.901. (3) Chlorderazin of 3 micro g/ml could increase the intracellular DNR accumulation significantly (P < 0.05), and the fluorescence staining by the flow cytometry was higher (250.95 +/- 18.96) than the control group (112.75 +/- 15.78) and shift right in K562/AO2 cells treated with chlorderazin, and the difference was significant (P < 0.05). (4) Chlorderazin has no significant influence to the expression level of mdr-1 mRNA. Both test group and control group showed a clear mdr-1 mRNA band located at the position of 157 kb. The ratios of mdr-1/beta-actin density were 0.414 +/- 0.012 in the test group and 0.447 +/- 0.027 in the control group, respectively, and the difference was not significant (P > 0.05).
  
  
  CONCLUSIONS
  Chlorderazin could reverse the multidrug resistance by increasing the intracellular DNR accumulation in K562/AO2 cells. The effects had no correlation to the mdr-1 gene. Further study is needed.
authors.affiliation: Department of Pediatrics, Shandong Provincial Hospital, Jinan 250021, China.
authors.forename: Li-jun
authors.initials: LJ
authors.lastname: Chen
authors.forename: Shao-hua
authors.initials: SH
authors.lastname: Shen
authors.forename: Hong-mei
authors.initials: HM
authors.lastname: Wang
authors.forename: Xin
authors.initials: X
authors.lastname: Ye
authors.forename: Sha-yi
authors.initials: SY
authors.lastname: Jiang
authors.forename: Fei
authors.initials: F
authors.lastname: Gao
authors.forename: Gui-mei
authors.initials: GM
authors.lastname: Li
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics; D000932:Antiemetics / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002746:Chlorpromazine / Q000494:pharmacology*; D018432:Drug Resistance, Multiple / Q000187:drug effects* / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D005434:Flow Cytometry; D006801:Humans; D020014:K562 Cells; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000932:Antiemetics; D012333:RNA, Messenger; D002746:Chlorpromazine