In this study, we examine the mechanism by which Wnt5A regulates the expression of these tumor-associated antigens and the implications of this regulation for melanoma therapy. == Materials and Methods == == Data Analysis of the Mannheim data set == The Mannheim data is available from NCBIs gene expression omnibus (www.ncbi.nlm.nih.gov/geo), under GEO Series accession #GSE4845. PKC inhibitors did not lower MART-1 levels. CTL activation studies demonstrated that increases in Wnt5A correspond to decreased CTL activation and vice versa, suggesting that targeting Wnt5A before immunotherapy may lead to the enhancement of current targeted immunotherapy for patients with metastatic melanoma. Keywords:Melanoma, immune surveillance, Wnt5A, STAT3, MART-1, GP100 == Introduction == Effective therapy for metastatic melanoma continues to elude us. Experimental therapies include manipulating tumor-infiltrating T lymphocytes to boost immune recognition of melanoma cells via specific antigens, as well as enhancing the antigenicity of tumor cells themselves (14). Melanomaassociated antigens include MART-1, TYRP-1 (gp75) or gp100 (SILV), the transcription of which is governed by the transcription factors SOX10, PAX3 and MITF. A recent study demonstrated that melanomas could be separated into three dominant cohorts based on their MITF status, motility and proliferation (5). Of these samples (known as the Mannheim data set), Cohort Treosulfan A consisted of highly proliferative melanoma cells with low metastatic potential and high MITF Treosulfan expression and Cohort C of weakly proliferative cells with high metastatic potential and low MITF expression. Another key discriminator between these cohorts was the gene hCIT529I10 Wnt5A, which was more highly expressed in the metastatic samples. We have previously implicated the gene Wnt5A in melanoma progression (68). Wnt5A is a non-canonical Wnt protein that signals via Ca2+/PKC (9). This gene was downregulated in melanomas that had better outcome, and its overexpression correlated with more aggressive disease (7). Interestingly, in the initial study by Bittner et al, the gene Melan-A/MART-1 (Melanoma Antigen Recognized by T cells-1) was second only to Wnt5A in its ability to distinguish less aggressive tumors from more aggressive ones and was inversely correlated with Wnt5A expression. Wnt5A overexpression or knockdown using siRNA in melanoma cells identified several genes that were suppressed by Wnt5A overexpression, including metastasis suppressors such as Kiss-1 (8). Further analysis of this data set has also highlighted the inverse relationship between Wnt5A and various tumor-associated antigens of melanocytic lineage, including TYRP-1, DCT, gp100, and MART-1. The implication of these data is that the overexpression of Wnt5A correlates with the downregulation of potent melanocytic antigens such as MART-1, and may actually regulate their expression in melanoma. In this study, we examine the mechanism by which Wnt5A regulates the expression of these tumor-associated antigens and the implications Treosulfan of this regulation Treosulfan for melanoma therapy. == Materials and Methods == == Data Analysis of the Mannheim data set == The Mannheim data is available from NCBIs gene expression omnibus (www.ncbi.nlm.nih.gov/geo), under GEO Series accession #GSE4845. This data set was generated from microarray analysis of 45 primary cultures of melanoma biopsies, using Affymetrix HG-U133 microarray chips. A Students two-tailed T-test(assuming equal variance) was used to determine statistical significance of variation of the specific genes among the cohorts. == Cell Lines == UACC-1273EV, UACC1273-4-3 and UACC1273-4-7, as well the cell lines UACC647, M93-047, and UACC903 have been previously described (8). T2 is a lymphoblastoid cell line deficient in TAP function, whose HLA class I proteins can be easily loaded with exogenous peptides (10) and was grown in RPMI, as were B16 melanoma cells. The melanoma cell line Mel526 (also grown in RPMI) was a generous gift from Drs. Steven A. Rosenberg and John Wunderlich, (Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD) and expresses high levels of MART-1. All media was supplemented with 10% fetal bovine serum, 100 units/ml penicillin/streptomycin, and 2mM L-glutamine (all from GIBCO/BRL, Grand Island, NY). Human T lymphocytes were cultured in RPMI with 10% human AB serum (Sigma, St. Louis, MO), 0.05M mercaptoethanol, 0.1mM non-essential amino acids, 0.1mM sodium pyruvate, 10mM HEPES (all from Invitrogen, Grand Island, NY) and 300 IU/ml IL-2 (Hoffmann-LaRoche). Murine splenocytes, collected from 8 week old Pmel-1 TCR Tg mice, were stimulated as described below and cultured in the same media as human T lymphocytes with the exception that human AB serum was replaced with 10% FCS. All T-cell cultures were supplemented with 100 units/ml penicillin/streptomycin and 2mM L-glutamine (Invitrogen). == Peptides and reagents == MART-1 peptide 2735 (AAGIGILTV) (11,12) was synthesized at the University of Maryland Biopolymer Laboratory. Rhodamine-tagged Wnt5A siRNA was designed as previously described (8) and purchased from Qiagen, Valencia, CA. Lipofectamine Plus was from Invitrogen, recombinant murine Wnt5A was from R and D Biosystems, Minneapolis, MN. G6983 (a specific inhibitor of PKC , , , , and , but not ) and the STAT3 inhibitor peptide were purchased.