Possible regulation of the immune modulator tetraspanin CD81 by alpha-synuclein in melanoma

We probed the mechanism by which the Parkinsons disease-associated protein -synuclein (-syn)/SNCA promotes the pathogenesis and progression of melanoma. We found that the human melanoma cell line SK-MEL-28 in which SNCA is knocked out (SNCA-KO) has low levels of tetraspanin CD81, which is a cell-surface protein that promotes invasion, migration, and immune suppression. Analyzing data from the Cancer Genome Atlas, we show that SNCA and CD81 mRNA levels are positively correlated in melanoma; melanoma survival is inversely related to the levels of SNCA and CD81; and SNCA/CD81 are inversely related to the expression of key cytokine genes (IL12A, IL12B, IFN, IFNG, PRF1 and GZMB) for immune activation and immune cell-mediated killing of melanoma cells. We propose that high levels of -syn and CD81 in melanoma and in immune cells drive invasion and migration and in parallel cause an immunosuppressive microenvironment; these contributing factors lead to aggressive melanomas. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=163 SRC="FIGDIR/small/593218v2_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@17513d4org.highwire.dtl.DTLVardef@168d161org.highwire.dtl.DTLVardef@8a4970org.highwire.dtl.DTLVardef@db7409_HPS_FORMAT_FIGEXP M_FIG C_FIG