Effect of PTEN knockout on dabrafenib-trametinib treatment in A375 melanoma cells - replicate 2

Approximately 50% of melanomas harbor an activating BRAFV600E mutation. Standard of care involves a combination of inhibitors targeting mutant BRAF and MEK1/2, the substrate for BRAF in the MAPK pathway. PTEN loss of function mutations occur in 40% of BRAFV600E melanomas, resulting in increased PI3K/AKT activity that enhances resistance to BRAF/MEK combination inhibitor therapy. To compare the response of PTEN null to PTEN wild type cells in an isogenic background, CRISPR was used to knock out PTEN in the A375 melanoma cell line that harbors a BRAFV600E mutation. Kinome profiling was performed using the parental line and two PTEN KO clones (5 and 11), treated with DMSO, or treated with 100nM dabrafenib and 10nM trametinib for 1 day or for 7 days. PTEN KO cells showed dramatically increased binding of HER3 and AKT3 compared to wild type. The activation of the SOX10-FOXD3-HER3-AKT axis in PTEN KO cells could be targeted with the ERBB/HER inhibitor neratinib.