Resveratrol Reduces the Hypoxia-Induced Resistance to Doxorubicin in Breast Cancer Cells

Abstract

Summary Resveratrol (3,4′,5-trihydroxy-trans-stilbene) is known to enhance the cytotoxicity of the anticancer drug doxorubicin. On the other hand, breast cancer MCF-7 cells acquire resistance to doxorubicin under hypoxic conditions. In this study, we investigated the effect of resveratrol on hypoxia-induced resistance to doxorubicin in MCF-7 cells. Resveratrol and its derivative 3,5-dihydroxy-4′-methoxy-trans-stilbene, but not 3,5-dimethoxy-4′-hydroxy-trans-stilbene, cancelled hypoxia-induced resistance to doxorubicin at a concentration of 10 mm. Carbonyl reductase 1 (CBR1) catalyzes the conversion of doxorubicin to its metabolite doxorubicinol, which is much less effective than doxorubicin. Hypoxia increased the expression of CBR1 at both mRNA and protein levels, and knockdown of CBR1 inhibited hypoxia-induced resistance to doxorubicin in MCF-7 cells. Knockdown of hypoxiainducible factor (HIF)-1a repressed the hypoxia-induced expression of CBR1. Resveratrol repressed the expression of HIF-1a protein, but not HIF-1a mRNA, and decreased hypoxiaactivated HIF-1 activity. Resveratrol repressed the hypoxia-induced expression of CBR1 at both mRNA and protein levels. Likewise, 3,5-dihydroxy-4′-methoxy-trans-stilbene decreased the hypoxia-induced expression of CBR1 protein, but not 3,5-dimethoxy-4′-hydroxy-transstilbene. Furthermore, resveratrol decreased the expression of HIF-1a protein even in the presence of the proteasome inhibitor MG132 in hypoxia. Theses results indicate that in MCF-7 cells, HIF-1a-increased CBR1 expression plays an important role in hypoxia-induced resistance to doxorubicin and that resveratrol and 3,5-dihydroxy-4′-methoxy-trans-stilbene decrease CBR1 expression by decreasing HIF-1a protein expression, perhaps through a proteasome-independent pathway, and consequently repress hypoxia-induced resistance to doxorubicin.

The modulation of carbonyl reductase 1 by polyphenols

“…Although, there is no direct evidence for increased CBR1 expression from the ingestion of polyphenols (with the exception of stilbenes (Mitani et al, 2014)), their induction effect on CBR1 is highly probable. From this point of view, induction of CBR1 by polyphenols could represent the way of improving chemoprotection.…”

“…Recently, the ability of stilbenes with 3,5-dihydroxy groups to decrease CBR1 expression in MCF-7 cells by decreasing HIF-1a protein expression was reported (Mitani et al, 2014). Many flavonoids have also been reported to suppress HIF-1a expression and hence down-regulate hypoxia-inducible genes, however, the connection between the effect of flavonoids on HIF-1a and CBR1 has never been assessed directly.…”

Up-Regulation of Carbonyl Reductase 1 Renders Development of Doxorubicin Resistance in Human Gastrointestinal Cancers

“…As mentioned above, some researches argued that transcriptional activation of CBR1 is regulated through a transcription factor hypoxia-inducible factor-1α. 18,19,29) Further accumulation of precise information about the factors responsible for the transcriptional regulation of CBR1 and sequence of the promotor region is therefore required to explain the clear discrepancy.…”

“…In addition, it was found that CBR1 is highly induced during the development of DOX resistance through formation of ROS, as well as previously reported hypoxia. 18,19) Based on results of our previous promotor gene analysis 30) and the marked induction during the treatment of LoVo cells with the Nrf2 activator SFN (Fig. 4A), we assume that up-regulation of CBR1 is mainly mediated due to activation of Nrf2/Kelch-like ECH-associated protein-1 (Keap1) signaling pathway.…”

“…9,16) To our knowledge, there are only three reports that propose the contribution of CBR1 to the mechanism underlying DOX resistance of breast cancer cells and hepatocellular carcinomas. [17][18][19] In this study, we monitored the expression of CBR1 in seven gastrointestinal cells, of which MKN45, LoVo and DLD1 cells with intrinsically different levels of CBR1 expression were chosen in order to establish the DOX-resistant variants. Since reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analyses revealed the up-regulation of CBR1 in the established DOX-resistant phenotypes of MKN45 and LoVo cells, the pathophysiological role of the enzyme in the DOX resistance was investigated by analyzing effects of its transient overexpression and specific inhibition on cytotoxicity of DOX.…”