Lenalidomide is an immunomodulatory drug and possesses anti-angiogenic and immunomodulatory activities against multiple myeloma. The present study assessed the in vitro effect of lenalidomide combined with cisplatin on MDA-MB-231, a triple-negative breast cancer (TNBC) cell line and explored the underlying molecular mechanism of this combination. Cell viability, apoptosis and the protein expression of phosphorylated (p) and total extracellular signal-regulated kinase (ERK), B-cell lymphoma-2 (Bcl-2), caspase-3, cleaved poly-adenosine diphosphate-ribose polymerase (cPARP), vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were measured in MDA-MB-231 cells treated with different concentrations of lenalidomide, cisplatin and their combination using different biochemical assays. Lenalidomide demonstrated no significant effect on the cell viability of MDA-MB-231 cells, even at high concentrations, whereas lenalidomide in combination with cisplatin, significantly reduced cisplatin IC50 from 7.8 to 3.0 µM in MDA-MB-231 cells. In addition, lenalidomide and cisplatin in combination significantly induced cell apoptosis by 1.6- and 1.38-fold, respectively compared with lenalidomide and cisplatin alone (P<0.05). The expression levels of VEGF, bFGF and Bcl-2 proteins were significantly reduced (P<0.01), whereas caspase-3 and cleaved PARP expression were significantly increased in MDA-MB-231 cells treated with the combination compared to those treated with single agents (P<0.01). Lenalidomide treatment alone significantly reduced the p-ERK level compared with the control (P<0.05) and cisplatin treatment alone significantly increased it (P<0.01), however treatment with them in combination significantly reduced the p-ERK level in MDA-MB-231 cells compared with cisplatin treatment alone (P<0.05). In conclusion, the present study provides the basis for using lenalidomide in combination with cisplatin in TNBC therapy.
Keywords: apoptosis; cisplatin; lenalidomide; triple-negative breast cancer.