[Inhibitory effects of capsaicin on migration and invasion of breast cancer MDA-MB-231 cells and its mechanism].

The aim of this study was to investigate the effects of capsaicin on migration and invasion of breast cancer MDA-MB-231 cells and its possible mechanism. The MDA-MB-231 cells were incubated in the medium containing different concentrations of capsaicin for 24 h. CCK-8 assay was employed to detect the cell viability. The cell migration and invasion were assessed by wound healing assay and transwell invasion assay, respectively. The protein levels of c-Src, p-c-Src (Tyr416), FAK, p-FAK (Tyr576), Paxillin, p-Paxillin (Tyr118), matrix metalloproteinase 2 (MMP2) and MMP9 in the MDA-MB-231 cells were detected by Western blotting. The mRNA expressions of MMP2 and MMP9 were measured by RT-PCR. The result showed that capsaicin (25 and 50 µmol/L) remarkably reduced the abilities of migration and invasion (P < 0.05), inhibited the phosphorylation of c-Src, FAK and Paxillin (P < 0.05), and down-regulated MMP2 and MMP9 expressions at mRNA and protein levels (P < 0.05) in MDA-MB-231 cells. These effects of capsaicin were all in dose-dependent manners. These results suggest that capsaicin may suppress the migration and invasion of breast cancer MDA-MB-231 cells by inhibiting the phosphorylations of c-Src, FAK and Paxillin, and down-regulating the mRNA and protein levels of MMP2 and MMP9.

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

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.