Serine/Arginine Protein Kinase Inhibitors Potentiate Melanoma Cell Death and Metastatic Inhibition Through Apoptotic Protein Triggering and Vimentin Dysregulation.

Purpose: Melanoma arises from the malignant transformation of melanocytes, a serious health problem in high UV-exposure countries. Ineffective treatments and metastasis have led to poor prognosis and high mortality among melanoma patients. Several underlying mechanisms are suspected. The splicing-error in many genes has been frequently reported in melanoma, therefore, targeting splicing regulator Serine/Arginine protein kinases (SRPKs) is promising. Methods: SRPKs expression in the TCGA dataset was analyzed by GEPIA. A375 and MNT-1 were comparatively treated by SRPK inhibitors, SRPIN340 and SPHINX31. Effects on viability and growth were measured by MTT and hanging drop assay. Apoptotic death was examined by flow cytometry and western blotting. Invasive ability was determined by transwell assay. Invasive-associated genes, proteins, and enzymes were tracked by RT-PCR, western blotting, immunofluorescence, and gelatin zymography. Results: SRPIN340 exhibited higher inhibitory effects on the viability and growth of melanoma cells than SPHINX31. Apoptotic induction was found with downregulated Bcl-2 and upregulated cytochrome c, especially in A375 cells. For metastatic inhibition in A375, lower numbers of invaded cells were counted. Downregulated vimentin mRNA and transcription factors-snail, as well as altered vimentin protein expression and localization were marked. Remarkably, the activities of MMP2 and MMP9 were suppressed. Conclusion: SRPK inhibitors potentially suppressed melanoma cell survivability and metastasis through the triggering of apoptotic proteins and dysregulating vimentin. These collected data serve as a basis for utilizing new alternative therapeutic strategies by targeting splicing regulator SRPK, for melanoma treatment.