gms | German Medical Science

Objective: Adiponectin, an adipocyte derived serum protein, positively affects glucose metabolism. Recently, adiponectin receptors (AdipoR) have been identified in heart and skeletal muscle (AdipoR1) and liver (AdipoR2), which might mediate insulin sensitizing effects. Serum adiponectin levels are inversely associated with breast cancer risk, but the molecular mechanisms underlying this association are not known. Thus, the purpose of this study was to investigate the action of adiponectin on breast cancer cells in vitro.

Methods: AdipoR1 and AdipoR2 mRNA expression was analyzed by means of real time RT-PCR in MCF-7, MDA-MB-231 and SKBR breast cancer cells. AdipoR1 antibody was used for western blot assay. MCF-7, MDA-MB-231 and SKBR-3 cells cultured in DMEM supplemented with FCS or serum replacement were treated with different concentrations of adiponectin. Relative numbers of viable cells were assessed by means of the resazurin-based Cell Titer Blue assay, cellular apoptosis was examined by measurement of activated caspases 3 and 7 by means of the luminometric Caspase-Glo assay.

Results: We were able to demonstrate expression of AdipoR1 and AdipoR2 in MCF-7, MDA-MB-231 and SK-BR-3 breast cancer cells on mRNA level. Furthermore, AdipoR1 protein could be detected by means of western blot analysis. Unexpectedly, treatment with higher concentrations of adiponectin resulted in a significantly decreased apoptosis under serum free conditions. In contrast, we were not able to detect a significant effect of adiponectin on proliferation of breast cancer cell lines neither in FCS medium nor in serum free medium.

Conclusion: Treatment with adiponectin is able to modulate apoptosis of human breast cancer cells in vitro. Our detection of AdipoR1 and 2 receptors in these cell lines calls for further studies to elucidate their function in breast cancer.