| dc.description.abstract | Vemurafenib (PLX4032) is a small molecule inhibitor of the mutant form of BRAF gene (BRAFV600E) for the treatment of melanoma. The resistance of BRAF inhibitor produced the secondary tumors in patients. Until now, the mechanisms of BRAFV600E inhibitor-induced secondary tumor development is not fully defined. It has been reported that most of the second tumors have 21%-60% RAS mutations, which enhances the BRAF-CRAF heterodimer formation to activate the MEK/ERK pathway. However, we hypothesize that the intercellular communication especially factors released from melanoma treated with BRAFV600E inhibitors may contribute to the
formation of secondary tumors which are originated from normal keratinocytes and epidermal cells. In this study, we utilized the conditioned medium (CM) collected from melanoma cells treated with BRAFV600E inhibitor, PLX4032, or PLX8394, a novel BRAFV600E inhibitor, to investigate our hypothesis. The migrative, and tumorigenic abilities of epidermal cells cultured with CM were detected by wound healing, and soft
agar assays. The results showed that normal keratinocytes and epithelial cells cultured with CM from melanoma cells treated with PLX4032 would enhance their migration,
and anchorage-independent growth as compared to the control group significantly. Since extracellular vehicles (EVs) as the important mediators that may act as cell-tocell communication in the tumor microenvironment, we investigated whether the EVs released from melanoma can affect tumorigenesis of keratinocytes or epithelial cells. Therefore, we isolated EVs from the conditioned medium, and confirmed the structure and characterization by Western blotting and TEM image. Taken together, our results
suggest that melanoma cells may release EVs to promote tumorigenesis in keratinocytes or the normal epithelial cells.
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