Abstract
In the present study, the anti-tumor effects of combination treatment with an siRNA targeting B-Raf proto-oncogene serine/threonine kinase (BRAF)V600E and phosphoinositide 3-kinase (PI3K) signaling pathway inhibitors was investigated in melanoma cell lines harboring BRAFV600E. Human melanoma A375 and WM115 cells were treated with siRNA targeting to BRAF or BRAFV600E, combined with treatment with PI3K signaling pathway inhibitors. CCK-8 and EdU proliferation assays were performed to assess cell viability and proliferation, respectively, following treatment. In addition, flow cytometry analysis was performed to determine cell cycle distribution, and western blot analysis was performed to analyze the activity of the extracellular signal-regulated kinase (ERK) and PI3Ksignaling pathways following treatment. Targeting BRAFV600E using small interfering (si)RNA significantly decreased cell viability and DNA replication in tumor cell lines that harbor oncogenic BRAFV600E. Inhibition of BRAFV600E by siRNA combined with treatment with PI3K or mammalian target of rapamycin signaling pathway inhibitors significantly decreased cell viability and proliferation compared with siRNA or inhibitor treatment alone. Concomitant BRAFV600E and PI3K inhibition led to G1/S phase arrest in melanoma cells. However, melanoma cells in which oncogenic BRAFV600E is not highly expressed (WM115 cells) were not sensitive to BRAFV600E targeted therapy. The PI3K signaling pathway inhibitors were more effective in this cell line. The results from the present study provide an insight into the potential effectiveness of combination therapy and personalized cancer treatments.