Erschienen in:
01.08.2010 | Original Article
Distinct molecular mechanisms leading to deficient expression of ER-resident aminopeptidases in melanoma
verfasst von:
Esther Kamphausen, Christiane Kellert, Tarish Abbas, Nadja Akkad, Stefan Tenzer, Graham Pawelec, Hansjoerg Schild, Peter van Endert, Barbara Seliger
Erschienen in:
Cancer Immunology, Immunotherapy
|
Ausgabe 8/2010
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Abstract
Immune surveillance of tumour cells by CD8+ cytotoxic T cells plays a key role in the establishment and control of an anti-tumour response. This process requires the generation of antigenic peptides, which are largely produced by the proteasome in combination with other proteases located in either the cytoplasm and/or the endoplasmic reticulum (ER). The ER-resident aminopeptidases ERAP1 and ERAP2 trim or even destroy HLA class I-binding peptides thereby shaping the peptide repertoire presented for T cell recognition. So far there exists limited information about the expression pattern of ERAP1 and/or ERAP2 in human tumours of distinct histotypes. Therefore, the expression profiles and modes of regulation of both aminopeptidases were determined in a large series of melanoma cell lines. A heterogeneous expression ranging from high to reduced or even total loss of ERAP1 and/or ERAP2 mRNA and/or protein expression was detected, which often could be induced/upregulated by interferon-γ treatment. The observed altered ERAP1 and/or ERAP2 expression and activity levels were either mediated by sequence alterations affecting the promoter or enzymatic activities, leading to either transcriptional and/or post-transcriptional downregulation mechanisms or limited or excessive processing activities, which both might have an impact on the antigenic peptide repertoire presented on HLA class I molecules.