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[Reversal of adriamycin resistance by digoxin in human breast cancer cell line MCF-7/adriamycin and its mechanism.] [Article in Chinese]

LI Bai-He, YUAN Lei, SHI Ran-Ran, WANG Jian-Guo^*

Laboratory of Molecular Biology, Luohe Medical College, Luohe 462002, China

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.

Key words: digoxin; MCF-7/ADR; hypoxia inducible factor-1α; multidrug resistance gene 1; apoptosis

Received: 2015-05-25　　Accepted: 2015-07-30

Corresponding author: 王建国　　E-mail: wr0395@sina.com

Citing This Article：

LI Bai-He, YUAN Lei, SHI Ran-Ran, WANG Jian-Guo. [Reversal of adriamycin resistance by digoxin in human breast cancer cell line MCF-7/adriamycin and its mechanism.] [Article in Chinese]. Acta Physiol Sin 2015; 67 (6): 611-617 (in Chinese with English abstract).