title: [Reversal of adriamycin resistance by digoxin in human breast cancer cell line MCF-7/adriamycin and its mechanism].
abstract: The aim of this study was to investigate the effects of digoxin on the chemoresistance of human breast cancer cell line MCF-7/adriamycin (ADR) and its underlying mechanism. MCF-7 and MCF-7/ADR cells were designated as control and ADR groups, respectively. MCF-7/ADR cells in ADR + digoxin group received 48 h of digoxin (10 nmol/L) treatment; MCF-7/ADR cells transfected with pLKO.1-shHIF-1α and pLKO.1-shcontrol plasmids were named shHIF-1α and shcontrol groups, respectively. CCK-8 assay was employed to detect the cytotoxic effect of ADR on MCF-7/ADR cells, and IC50 value and resistance index were calculated according to CCK-8. RT-PCR was used to measure the mRNA levels of hypoxia inducible factor-1α (HIF-1α) and multidrug resistance-1 (MDR1). Western blot was used to analyze the protein levels of HIF-1α and MDR1. Flow cytometry was used to determine the apoptosis. The result showed that the resistance index of MCF-7/ADR cells was 115.6, and it was reduced to 47.2 under the action of digoxin (P < 0.05). In comparison with control group, ADR groups showed increased protein and mRNA levels of HIF-1α and MDR1 (P < 0.05). Digoxin reduced the protein levels of HIF-1α and MDR1, as well as the mRNA level of MDR1, but did not affect the mRNA level of HIF-1α. After HIF-1α gene was silenced, the protein levels of HIF-1α and MDR1 were down-regulated (P < 0.05), and the pro-apoptotic effect of ADR on MCF-7/ADR cells was enhanced. Although it was also observed that digoxin promoted cell apoptosis in both shcontrol and shHIF-1α groups, the difference between the two groups was not significant. In conclusion, the results suggest that digoxin may partially reverse the ADR resistance in human breast cancer cell line MCF-7/ADR by means of down-regulating the expression levels of HIF-1α and MDR1 and promoting apoptosis via HIF-1α-independent pathway.
authors.affiliation: Laboratory of Molecular Biology, Luohe Medical College, Luohe 462002, China.
authors.forename: Bai-He
authors.initials: BH
authors.lastname: Li
authors.affiliation: Laboratory of Molecular Biology, Luohe Medical College, Luohe 462002, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Laboratory of Molecular Biology, Luohe Medical College, Luohe 462002, China.
authors.forename: Ran-Ran
authors.initials: RR
authors.lastname: Shi
authors.affiliation: Laboratory of Molecular Biology, Luohe Medical College, Luohe 462002, China. wr0395@sina.com.
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Wang
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000378:metabolism; D017209:Apoptosis; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D004077:Digoxin / Q000494:pharmacology*; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D061986:MCF-7 Cells / Q000187:drug effects; D012333:RNA, Messenger; D014162:Transfection
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D004077:Digoxin; D004317:Doxorubicin