Combination of Salermide and Cholera Toxin B Induce Apoptosis in MCF‑7 but Not in MRC‑5 Cell Lines

Background: Sirtuin1 is an enzyme that deacetylates histones and several non‑histone proteins including P53 during the stress. P300 is a member of the histone acetyl transferase family and enzyme that acetylates histones. Hereby, this study describes the potency combination of Salermide as a Sirtuin1 inhibitor and cholera toxin B (CTB) as a P300 activator to induce apoptosis Michigan Cancer Foundation‑7 (MCF‑7) and MRC‑5. Methods: Cells were cultured and treated with a combination of Salermide and CTB respectively at concentrations of 80.56 and 85.43 μmol/L based on inhibitory concentration 50 indexes at different times. The percentage of apoptotic cells were measured by flow cytometry. Real‑time polymerase chain reaction was performed to estimate the messenger ribonucleic acid expression of Sirtuin1 and P300 in cells. Enzyme linked immunosorbent assay and Bradford protein techniques were used to detect the endogenous levels of total and acetylated P53 protein generated in both cell lines. Results: Our findings indicated that the combination of two drugs could effectively induced apoptosis in MCF‑7 significantly higher than MRC‑5. We showed that expression of Sirtuin1 and P300 was dramatically down‑regulated with increasing time by the combination of Salermide and CTB treatment in MCF‑7, but not MRC‑5. The acetylated and total P53 protein levels were increased more in MCF‑7 than MRC‑5 with incubated combination of drugs at different times. Combination of CTB and Salermide in 72 h through decreasing expression of Sirtuin1 and P300 genes induced acetylation of P53 protein and consequently showed the most apoptosis in MCF‑7 cells, but it could be well‑tolerated in MRC‑5. Conclusion: Therefore, combination of drugs could be used as an anticancer agent.