H1, a novel derivative of tetrandrine reverse P-glycoprotein-mediated multidrug resistance by inhibiting transport function and expression of P-glycoprotein.
OBJECTIVE
H1 is a novel derivative of tetrandrine (Tet). Here we investigate the ability of H1 to reverse P-glycoprotein (Pgp)-mediated multidrug resistance (MDR) and its mechanisms.


METHODS
KBv200, MCF-7/adr and their parental sensitive cell lines KB, MCF-7 were used for reversal study. The intracellular accumulation and efflux studies with Pgp substrates of doxorubicin and rhodamine 123 were determined by flow cytometry. The expression of Pgp was investigated by Western blot and RT-PCR analysis. ATPase activity of Pgp was performed by Pgp-Glo(™) assay systems. The ubiquitination level of Pgp was determined by immunoprecipitation analysis. The effect of ERK1/2 on Pgp expression in KBv200 cells were investigated by RNA interference.


RESULTS
H1 significantly potentiated the sensitivity of Pgp substrates in KBv200 and MCF-7/adr cells, but not in parental cells KB and MCF-7. H1 inhibited Pgp expression in KBv200 cells in a dose-dependent manner, but had no effect on MDR1 expression. Further studies showed that H1 prompted the degradation of Pgp and decreased Pgp protein half-life by enhancing the ubiquitination of Pgp, which may be related to downregulated MEK-ERK signal pathway. We also found H1 inhibited ATPase activity of Pgp in a dose-dependent manner.


CONCLUSIONS
H1 is an effectively and potential agent in reversing Pgp-mediated MDR by inhibiting the transport function and expression of Pgp.
Wei
Ning
N
Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, 1 Xian Nong Tan Street, 100050 Beijing, China.
Sun
Hua
H
Wang
Fengpeng
F
Liu
Gengtao
G
D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis*; D000903:Antibiotics, Antineoplastic / Q000378:metabolism; D044182:Benzylisoquinolines / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000378:metabolism; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D021381:Protein Transport; D034622:RNA Interference; D020112:Rhodamine 123 / Q000378:metabolism; D015398:Signal Transduction
C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D044182:Benzylisoquinolines; D005456:Fluorescent Dyes; C558842:H1 (tetrandrine derivative); D020112:Rhodamine 123; C009438:tetrandrine; D004317:Doxorubicin; C482128:MAP2K2 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human