Modulatory Effect of Sodium Butyrate on the Anticancer Activity of Abemaciclib in MDA-MB-231 Human Breast Cancer Cells

Triple negative breast cancer is the most aggressive subtype of breast cancer, and its treatment is limited. The effect of abemaciclib and /or sodium butyrate on MDA-MB-231 triple negative breast cancer cells was investigated. The IC50 for the growth inhibitory effects of abemaciclib, sodium butyrate, and their combination were 14.55 μM, 7.08 mM, and 3.743 mM, respectively. The combination showed a synergistic interaction with a decrease in IC50 to 2.55 μM abemaciclib and 3.74 mM butyrate. Three replicates of four groups of cancer cells were treated for 48 hr with the IC50 of abemaciclib, butyrate or their high or low dose combinations. A fifth group was treated with complete medium and served as the control. Cell migration, protein expression levels of cyclin D1, E2F2 transcription factor, phosphorylated AKT, nuclear factor kappa B (NF-κB), cyclin dependent kinase-2 (CDK2), retinoblastoma (Rb), p16INK4a, p53 and mRNA levels of CDK2, p16INK4a and p53 were assessed in all treated groups. Combination treatment with abemaciclib and butyrate showed a significant attenuation of cell metastasis. The combination treatment was associated with a decrease in E2F2, CDK2, and NF-κB protein levels together with attenuation in AKT phosphorylation level. The combination also showed an elevation in Rb, and p16INK4a, together with a reversal of DNA hypo-methylated state. Although abemaciclib monotherapy failed to alter cyclin D1 or p53 levels, the combination significantly reduced cyclin D1 level together with an increase in P53 level. In conclusion, combining butyrate with abemaciclib augmented its antiproliferative and antimetastatic effects and induced apoptotic activity