Inhibition of triple-negative breast cancer proliferation and motility by reactivating p53 and inhibiting overactivated Akt

Mutations of p53 tumor suppressors occur more frequently in cancers at advanced stages or in more malignant cancer subtypes such as triple-negative breast cancer. Thus, restoration of p53 tumor suppressor function constitutes a valuable cancer therapeutic strategy. In the present study, it was revealed that a specific inhibitor of histone deacetylase 6, ACY-1215, caused increased acetylation of p53 in breast cancer cells with mutated p53, which was accompanied by increased expression of p21. These results suggested that ACY-1215 may lead to enhanced transcriptional activity of p53. It was also determined that ACY-1215 treatment resulted in G1 cell cycle arrest and apoptosis in these cancer cells. Furthermore, ACY-1215 displayed a synergistic effect with specific inhibitors of ATM, an activator of Akt, in inducing cancer cell apoptosis and inhibiting their motility. More importantly, it was observed that combination of ACY-1215 and ATM inhibitors exhibited markedly more potent antitumor activity than the individual compound in xenograft mouse models of breast cancer with mutant p53. Collectively, our results demonstrated that ACY-1215 is a novel chemotherapeutic agent that could restore mutant p53 function in cancer cells with strong antitumor activity, either alone or in combination with inhibitors of the ATM protein kinase.