GFP-REPORTER CONSTRUCTS FOR TUMOR ANTIGEN REGULATION

The goals of this Phase I project are to develop stable melanoma cell lines containing a reporter gene linked to the Melan-NMART-1 promoter for use in high throughput drug screening. We propose to develop these cell lines to identify drugs that up-regulate Melan-A/MART-1 expression. Loss of tumor antigens represents an unmet obstacle to immune-based therapies (including vaccines). Since T cell recognition relies on both the expression of tumor antigen target and concomitant presentation of antigen peptides by HLA molecules, loss of either nominal antigen or the presenting HLA molecule will prevent T cell-recognition of such tumor variants. We recently discovered a novel mechanism for the reversible down-regulation of the melanoma tumor associated antigen, Melan-A/MART-1. Such down-modulation, which we call "antigen silencing," exemplifies one route by which a tumor can escape immune destruction in the presence of tumor specific cytotoxic T-cells. We propose to identify novel drugs that up-regulate Melan-A/MART-1 antigen expression using reporter cell lines in high throughput screens. Such novel drugs will induce the maintenance and/or up-regulation of tumor antigen expression necessary to achieve efficacy in cellular immune-based tumor therapies.