title: [Mechanism of synergistic anti-tumor effect of PH II -7 with doxorubicin on multi-drug resistant HL-60/ADR cells].
abstract: OBJECTIVE
  To study the synergistic mechanism between PH II -7 and doxorubicin against multi-drug resistant HL-60/ADR cells and its parent HL-60 cells.
  
  
  METHODS
  The anti-tumor activity of doxorubicin alone and combined with PH II -7 were measured by MTT assay. RNA was extracted from the cells treated with PH II -7 for different times or doses then the expression of MRP gene was measured by RT-PCR. Confocal laser scanning microscopy and FACS were used to detect the intracellular cumulation of doxorubicin in PH II -7 treated HL-60 and HL-60/ADR cells.
  
  
  RESULTS
  PH II -7 has anti-tumor effect with IC50 of (0.83 +/- 0.08) micromol/L and (1.74 +/- 0.56) micromol/L for HL-60 and HL-60/ADR, respectively. It could potentiate the anti-tumor effect of doxorubicin with CDI of 0.7 and 0.43 for HL-60 and HL-60/ADR, respectively. PH II -7 and doxorubicin act synergistically in inhibiting the proliferation of HL-60 and HL-60/ADR cells and down-regulating the expression of MRP gene in a dose and time dependent manner. PH II -7 restored the intracellular cumulation of doxorubicin in HL-60/ADR cells to 55% of that in HL-60 cells.
  
  
  CONCLUSIONS
  PH II -7 can significantly hasten the cytotoxicity of doxorubicin to HL-60 and HL-60/ADR cells through down-regulating the expression of MRP. The synergistic effect was more obvious in HL-60/ADR cells.
authors.affiliation: State Key Laboratory of Experiment Hematology, Institute of Hematology and Blood Diseases Hospital, CAMS & PUMC, Tianjin 300020, China.
authors.forename: Yan-Jun
authors.initials: YJ
authors.lastname: Zhang
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.forename: Xiao-Feng
authors.initials: XF
authors.lastname: Shao
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Fan
authors.forename: Yuan-Fu
authors.initials: YF
authors.lastname: Xu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.forename: Ye
authors.initials: Y
authors.lastname: Su
authors.forename: Dong-Sheng
authors.initials: DS
authors.lastname: Xiong
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology*; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004357:Drug Synergism; D018922:HL-60 Cells; D006801:Humans
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004317:Doxorubicin