B-AP15 inhibited colon cancer cell proliferation by decreasing CDK6, Cyclin A, Cyclin E, c-Myc, and VEGF gene expression

This study evaluated the screening of novel possible target proteins of B-AP15 (NSC687852) in silico. Through in vitro investigation, the anticancer activity of B-AP15 was examined with respect to gene expression and cell proliferation of SW620 cells (colon cancer cells). Twenty proteins associated with colon cancer were selected to screen possible target proteins of B-AP15 using molecular docking. The binding position of B-AP15 and the top five candidate proteins were investigated using the Discovery Studio 2021 software program. Cytotoxicity, colonization ability, and cell inhibition were evaluated in SW620 cells for 24, 48, and 72 h via MTT assay, colony formation assay, and trypan blue assay. The gene expression was estimated using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) at 48 h. B-AP15 showed higher binding to E2F8 (- 10.88 kcal/mol), Ras (- 10.86 kcal/mol), GSK3B (- 10.77 kcal/mol), CDK6 (- 10.75 kcal/mol), and Raf (- 10.12 kcal/mol) than to USP14 (- 7.83 kcal/mol) as a target protein of B-AP15. Interestingly, Ras, GSK3B, and CDK6 shared the binding position between B-AP15 and known inhibitors. The IC50 values of B-AP15 against SW620 cells for 24, 48, and 72 h were 0.89 +/- 0.0019 mu M, 1.38 +/- 0.16 mu M, and 1.77 +/- 0.0016 mu M, respectively. B-AP15 reduced cell viability and the size and number of colonies and increased cell inhibition in a time- and dose-dependent manner. CDK6, Cyclin A, and VEGF expression were inhibited at B-AP15 concentrations of 0.89 and 1.78 mu M after treatment for 48 h. Cyclin E and cMyc expression were suppressed only at 1.78 mu M. These results suggest that B-AP15 possesses cytotoxicity, reducing the size and number of colonies and increasing cell inhibition via suppression of CDK6, Cyclin A, Cyclin E c-Myc, and VEGF.