Transporter (TAP)- and proteasome-independent presentation of a melanoma-associated tyrosinase epitope.

Abstract

The melanosomal protein tyrosinase is considered as a target of specific immunotherapy against melanoma. Two tyrosinase-derived peptides are presented in association with HLA-A2.1 [Wölfel et al., Eur. J. Immunol., 24, 759-764 (1994)]. Peptide 1-9 (MLLAVLYCL) is generated from the putative signal sequence. The internal peptide 369-377 is posttranslationally converted at residue 371, and its presentation is dependent on functional TAP transporters and proteasomes [Mosse et al., J. exp. Med.187, 37-48 (1998)]. Herein, we report on the processing and transport requirements for the signal sequence-derived peptide 1-9 that were studied in parallel to those for peptide 369-377. After infection of TAP-deficient (T2) and TAP-positive (T1) cells with a Modified Vaccinia Ankara construct carrying the human tyrosinase gene (MVA-hTyr), we found that recognition by CTL against peptide 1-9 did not require TAP function as opposed to recognition by CTL against peptide 369-377. When target cells with intact processing and transport functions were infected with MVA-hTyr, lysis by CTL against peptide 1-9 was not impaired by lactacystin, a specific inhibitor for the proteasome, whereas lysis by CTL against peptide 369-377 was completely abrogated. Taken together, peptide 1-9 derived from the signal sequence of tyrosinase is presented in a TAP-independent fashion and does not require proteasomes for processing. Cellular immune responses against this hydrophobic peptide can be monitored with lymphokine spot assays as documented in the case of a patient with metastatic melanoma, in whom we observed a preferential T-cell response against tyrosinase peptide 1-9 subsequent to chemoimmunotherapy. Independence of cytosolic processing and transport pathways and potentially enhanced expression levels make signal sequence-derived peptides and their carrier proteins important candidates for specific immunotherapy.

• Authors: C Wölfel, I Drexler, A Van Pel, T Thres, N Leister, W Herr, G Sutter, C Huber, T Wölfel
• Journal: International journal of cancer (Int J Cancer) Vol. 88 Issue 3 Pg. 432-8 (Nov 01 2000) ISSN: 0020-7136 [Print] United States
• PMID: 11054673 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• ATP Binding Cassette Transporter, Subfamily B, Member 2
• ATP-Binding Cassette Transporters
• Epitopes
• HLA-A2 Antigen
• Multienzyme Complexes
• Protein Sorting Signals
• TAP1 protein, human
• Monophenol Monooxygenase
• Cysteine Endopeptidases
• Proteasome Endopeptidase Complex

Topics

• ATP Binding Cassette Transporter, Subfamily B, Member 2
• ATP-Binding Cassette Transporters (physiology)
• Antigen Presentation
• Cysteine Endopeptidases (physiology)
• Epitopes
• HLA-A2 Antigen (physiology)
• Humans
• Melanoma (immunology)
• Monophenol Monooxygenase (immunology)
• Multienzyme Complexes (physiology)
• Proteasome Endopeptidase Complex
• Protein Sorting Signals
• T-Lymphocytes, Cytotoxic (immunology)
• Tumor Cells, Cultured