Enhancement of Human Melanoma Antigen Expression by IFN-β

Abstract

Although many immunotherapeutic investigations have focused on improving the effector limb of the antitumor response, few studies have addressed preventing the loss of tumor-associated Ag (TAA) expression, associated with immune escape by tumors. We found that TAA loss from human melanomas usually results from reversible gene down-regulation, rather than gene deletion or mutation. Previously, we showed that inhibitors of MAPK-signaling pathways up-regulate TAA expression in melanoma cell lines. We have now identified IFN-β as an additional stimulus to TAA expression, including Melan-A/MART-1, gp100, and MAGE-A1. IFN-β (but neither IFN-α nor IFN-γ) augmented both protein and mRNA expression of melanocytic TAA in 15 melanoma lines (irrespective of initial Ag-expression levels). Treatment of low Ag melanoma lines with IFN-β increased expression of melanocyte-lineage Ags, inducing susceptibility to lysis by specific CTLs. Treatment with IFN-β also enhances expression of class I HLA molecules, thereby inducing both nominal TAA and the presenting HLA molecule. Data from fluorescent cellular reporter systems demonstrated that IFN-β triggers promoter activation, resulting in augmentation of Ag expression. In addition to enhancing TAA expression in melanomas, IFN-β also stimulated expression of the melanocytic Ag gp100 in cells of other neural crest-derived tumor lines (gliomas) and certain unrelated tumors. Because IFN-β is already approved for human clinical use in other contexts, it may prove useful as a cotreatment for augmenting tumor Ag expression during immunotherapy.

Type-I-interferons in infection and cancer: Unanticipated dynamics with therapeutic implications

“…More recently, these discoveries were characterized by Dunn et al, who showed that IFN-b simultaneously augments TAAs (e.g., Melan-A/MART-1, gp100 and MAGE-A1) and HLA-class-I thus increasing the likelihood of improved immune recognition and cytotoxic killing of tumor targets, respectively. 64 The EMT is a process by which epithelial cells lose their polarization and cell-cell contacts and undergo remarkable morphologic changes switching from an epithelial cobblestone phenotype to an elongated fibroblastic phenotype. 65 The EMT provides for the evolution of cancer cells to the metastatic phenotype and contributes to their invasiveness, stemness and drug resistance.…”

A Screening Assay to Identify Agents That Enhance T-Cell Recognition of Human Melanomas

“…Previous experience has suggested that a 3 day treatment period would be suitable for evaluation of antigen-enhancing effects of either small molecules or protein mediators, [25][26][27] and this time frame was also validated with the IL-2 assay coculture assay. 27 We chose to use a concentration of 10 mM for library screening.…”

“…26 Since the transduced TCR used in the responding J-TCR-M1 cells is restricted by HLA-A2, the tumor cells were of necessity HLA-A2+ . We evaluated several candidate melanoma cell lines for the ability to stimulate the J-TCR-M1 cell line.…”

“…Also, previous experience has shown that promoter enhancement is indeed a common feature of known antigen upregulators, from small molecules to proteins. [25][26][27] The seven hits (excluding PMA) from the primary screen were evaluated over a dose range as shown in Figure 7. Again, the hits separated into three groups based on these results.…”

“…18,19 Such changes leave the relevant coding sequences intact and are, in principle, reversible. We, and others, have identified small molecules (such as MEK and B-raf inhibitors 25 ) and cytokines (such as interferon-beta [IFN-beta] 26 )…”