GILT Expression in Human Melanoma Cells Enhances Generation of Antigenic Peptides for HLA Class II-Mediated Immune Recognition

Jessica D Hathaway-Schrader,Duncan Norton,Azizul Haque,Katherine Hastings,Jennifer R Bethard,Janice S Blum,Bently P Doonan,Shaun Tompkins Fritz

doi:10.3390/ijms23031066

Abstract

Melanoma is an aggressive skin cancer that has become increasingly prevalent in western populations. Current treatments such as surgery, chemotherapy, and high-dose radiation have had limited success, often failing to treat late stage, metastatic melanoma. Alternative strategies such as immunotherapies have been successful in treating a small percentage of patients with metastatic disease, although these treatments to date have not been proven to enhance overall survival. Several melanoma antigens (Ags) proposed as targets for immunotherapeutics include tyrosinase, NY-ESO-1, gp-100, and Mart-1, all of which contain both human leukocyte antigen (HLA) class I and class II-restricted epitopes necessary for immune recognition. We have previously shown that an enzyme, gamma-IFN-inducible lysosomal thiol-reductase (GILT), is abundantly expressed in professional Ag presenting cells (APCs), but absent or expressed at greatly reduced levels in many human melanomas. In the current study, we report that increased GILT expression generates a greater pool of antigenic peptides in melanoma cells for enhanced CD4+ T cell recognition. Our results suggest that the induction of GILT in human melanoma cells could aid in the development of a novel whole-cell vaccine for the enhancement of immune recognition of metastatic melanoma.

Highlights

Melanoma is one of the most rapidly growing cancers plaguing western populations [1,2,3]
While melanoma cells that express human leukocyte antigen (HLA) class II molecules typically express measurable levels of invariant chain (Ii) and HLA-DM, the detection of gamma-IFN-inducible lysosomal thiol-reductase (GILT) within these tumor lines varies, with some tumors expressing little to no GILT enzyme [15,50]
To examine mechanistically the impact of GILT expression on the HLA class II pathway and Ag presentation in melanomas, two melanoma lines with low to no detectable GILT protein were transduced with a plasmid to promote sustained human GILT expression, or a control empty vector [50]

Summary

Introduction

Melanoma is one of the most rapidly growing cancers plaguing western populations [1,2,3]. Treatments of early stage melanoma include surgery, radiation, and chemotherapy, which are generally effective at eradicating the disease; but in the case of late stage metastatic melanoma, there is no curative option [4,5,6]. To fill this gap in viable treatment options, immunotherapy has been tried in multiple forms over the past decade. A recent study showed that the downregulation of GILT by lentiviral-mediated silencing inhibited cell growth, colony formation, and migration. Our current study looks to dissect novel antigen (Ag) processing reactions in melanoma that could be exploited for loaded dendritic cell and melanoma whole-cell vaccine strategies

Methods

Results

Conclusion