Regulation of sphingosine kinases and sphingosine-1-phosphate receptors expression in melanoma cells resistant to vemurafenib

PEREZ CELIA; MONS J; CAMPOS, LE; FALCON C; FERNANDEZ JM; GUERRERO ME; ZOPPINO F; ALVAREZ SE

Virtual

Congreso; SAIC 2021; 2021

Over the last years, the incidence of melanoma, the deadliest form of skin cancer, has risen faster than any other cancer type. Considering that half of the patient?s exhibit the BRAFV600E mutation, therapies with BRAF and MEK inhibitors (BRAFi/MEKi) showed an impressive success rate. Unfortunately, treatments are marginally effective since tumors quickly become resistant. In that regard, accumulating evidence supports that sphingosine-1-phosphate (S1P) is linked to multiple mechanisms leading to cancer progression and resistance. Thus, the aim of this study was to evaluate how vemurafenib (BRAFi) resistance affects the expression of sphingosine kinases (SphK) and S1P receptors (S1PR) in melanoma. To this end, we generated vemurafenib-resistant melanoma cells by continuous exposure of parental sensitive cells to increasing concentrations (0,01µM ? 1µM) of the drug for 3 months. Previously, we showed that vemurafenib-resistant Lu1205 melanoma cell (Lu1205R) exhibit higher IC50 and pERK levels than their sensitive parents (Lu1205S). Here, we extended those studies to A375 melanoma cells. Certainly, A375R cells also showed increased resistance and pERK, but not pAKT levels. Expression of SphK and S1PR in both cells lines was evaluated by RT-qPCR. Surprisingly, the modulation of SphK1, S1PR1 and S1PR3 expression differ in Lu1205R and A375R cells. In addition, a bioinformatic analysis was performed using the public Gene Expression Omnibus (GEO) database (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE24862). This study showed a differential gene expression pattern in other cell lines, including A375, supporting the concept that melanoma heterogeneity may trigger different mechanisms of resistance to BRAFi therapy. In summary, although our results indicate that S1P signaling may have a role in vemurafenib resistance, further studies will be necessary to elucidate its importance.