TLR2/6 agonists and IFNgamma induce CXCL10 from melanoma

Clinical approaches to treat advanced melanoma include immune therapies, whose benefits depend on tumor-reactive T-cells to infiltrate metastases. However, most tumors lack significant immune infiltration prior to therapy, and some immune therapies are hindered by a persistent lack of immune cell infiltration. CXCL10 has been implicated as a critical chemokine supporting T-cell migration into tumors; thus agents that induce CXCL10 in tumors may improve patient responses to systemic immune therapy. We find that melanoma cells treated with TLR2/6 agonists (MALP-2 or FSL-1) and interferon-gamma (IFNgamma) upregulate CXCL10 production, when compared to IFNgamma treatment alone or no treatment. Gene profiling of melanoma cells lines treated with TLR2/6 agonists and IFNgamma demonstrate that a selective profile of genes are induced which may be favorable for promoting immune cell infiltration of tumors. TLR2 and TLR6 are widely expressed on human melanoma cells, and treatment of melanoma cells with TLR2/6 agonists and IFNgamma does not hinder melanoma cell apoptosis or promote proliferation. Furthermore, melanoma cells from surgically resected patient tumors upregulate CXCL10 production after treatment with TLR2/6 agonists and IFNgamma when compared to treatment with either agent alone. Collectively, these data identify TLR2/6 agonists and IFNgamma as a novel target for promoting CXCL10 production directly from melanoma cells.

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