Cellular activities of Serine-Arginine Protein Kinase inhibitors in cutaneous and ocular melanoma cells

Abstract

Melanoma is a tumor resulting from the malignant transformation of melanocytes in various organ, include skin and eye. This cancer is a serious health problem in countries with high sun or UV exposure. Due to a generally late detection, high invasive and metastatic properties, and the lack of effective treatments in melanoma. That reason lead to melanoma has very poor prognostic and high mortality rate. Aberrant alternative splicing lead to the expression of aberrant mRNA transcripts has been associated in the progression of various cancers. Serine/Arginine-riched Splicing Factors (SRSFs) are responsible for an alternative splicing and their functions are regulated by phosphorylation via Serine-Arginine Protein Kinases (SRPKs) that have been reported an overexpression in melanoma cells. In this study, the effects of SRPK1/2-specific inhibitor SRPIN340 and SRPK1-specific inhibitor SPHINX31 (SRPKi) were demonstrated. The phosphorylation profile in A375 cutaneous and 92-1 ocular melanoma cells in comparison with HaCat keratinocyte, were investigated by Western blot. The result found that most of phosphorylation profile more highly expressed in A375 and 92-1 than HaCat. Then, cell viability in A375 in comparison with 92-1, were determined by MTT viability assays. The result showed that the effect of SRPKi on viability of melanoma cells were presented as dose- and time-dependent manners. Next, the molecular effects of SRPKi treatment on melanoma cells were determined, using Western blot. Suppression of phosphorylated forms (pSRSFs) was observed. Then, SRSFs translocation were confirmed by Immunocytofluorescent (ICF) and show that SRSFs presented in cytoplasmic greater than nucleus. Proliferation ability of melanoma cells was examined by clonogenic assay, the results showed that both SRPIN340 and SPHINX31 reduced the size of cancer cell colonies. Particularly, in 92-1 cell showed more sensitive to SRPIN340 than A375 cell. Furthermore, both SRPIN340 and SPHINX31 could reduce AKT phosphorylation through dysfunction of SRPKs. The findings from this study should serve as the basis information for targeting SRPKs as an alternative therapeutic strategy and its downstream pathways.

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