Resveratrol as a Dual MAPK/STAT3 Inhibitor in Glioblastoma: Mutation-Dependent Therapeutic Efficacy

Background: Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor with limited treatment options. Tumors harboring the BRAF^V600E mutation exhibit aggressive behavior and present therapeutic challenges. Although dabrafenib/trametinib (D+T) target the BRAF/MAPK pathway and show efficacy in BRAF^V600E mutant melanoma, their effectiveness against GBM remains unclear. RES demonstrates anti-GBM activity through the inhibition of multiple signaling pathways. This study evaluated the therapeutic potential of RES either in monotherapy or in combination with D+T in GBM cells with and without the BRAF^V600E mutation. Methods: BRAF^V600E mutational status was confirmed in LN428 and U251 GBM cell lines using Sanger Sequencing. Cell proliferation and viability was assessed by CCK-8, EdU assay and Calcein AM/PI staining, cell morphology by H&E staining, cell migration by Transwell assay, and Apoptosis by TUNEL assay. The protein expressions of BRAF, PERK, and pSTAT3 were analyzed by Western blot, immunocytochemistry (ICC), and immunofluorescence (IF) following treatment with RES, D+T, or their combination. Statistical significance was determined using one-way ANOVA followed by Dunnett's post hoc test with p < 0.05. Results: Sanger Sequencing confirmed the presence of the BRAF^V600E mutation in the LN428 cells and its absence in the U251 cells. In the BRAF^V600E mutant LN428 cells, neither RES, D+T, nor their combination inhibited cell proliferation or migration, nor did they induce Apoptosis. In contrast, RES monotherapy significantly suppressed proliferation, reduced migration, and induced Apoptosis in the wild-type U251 cells, while D+T showed minimal inhibitory effects in both cell lines. Western blotting, ICC, and IF analyses revealed that RES significantly downregulated both PERK and pSTAT3 expression in the U251 cells but failed to produce similar effects in the LN428 cells. Notably, D+T treatment induced marked upregulation of pSTAT3 in both cell lines, which was effectively reversed by RES treatment in the U251 cells but not in the LN428 cells. Conclusions: RES selectively suppressed the MAPK and STAT3 signaling pathway in the BRAF wild-type U251 cells, while demonstrating no significant inhibitory effects in the BRAF mutant LN428 cells. This differential response indicates that mutational background governs MAPK/STAT3 pathway regulation, positioning RES as a promising dual-pathway inhibitor in mutation-stratified GBM therapeutics.