Therapeutic natural compounds Enzastaurin and Palbociclib inhibit MASTL kinase activity preventing breast cancer cell proliferation

Microtubule-associated serine/threonine kinase-like (MASTL) regulates mitotic progression and is an attractive target for the development of new anticancer drugs. In this study, novel inhibitory molecules were screened against MASTL kinase, a protein involved in cell proliferation in breast cancer. Natural source-derived drugs Enzastaurin and Palbociclib were selected to identify their role as MASTL kinase inhibitors. Cytotoxic activity, kinase activity, and other cell-based assays of Enzastaurin and Palbociclib were evaluated on human breast cancer (MCF-7) cells. The potential natural compounds caused cytotoxicity in MCF-7 cells in a dose- and time-dependent manner. Further analysis by Annexin V and PI staining indicated that both drugs are potent inducers of apoptosis. Enzastaurin induced G2/M phase arrest, while Palbociclib caused G1 arrest. MASTL kinase activity was significantly abrogated with both the compounds showing EC50 values of 17.13 mu M and 10.51 mu M, respectively. Taken together, these data strongly suggest that Enzastaurin and Palbociclib possess the ability to inhibit MASTL kinase activity and induce cell death in breast cancer cells, thus exhibiting significant therapeutic potential.