Functional deficiencies of components of the MHC class I antigen pathway in human tumors of epithelial origin.
An association between oncogenic transformation and repression of different components of the MHC class I antigen processing machinery (APM) have been described in murine model systems. In order to discover whether a similar correlation exists, human tumor cell lines of distinct histology with altered ras protein were analyzed for the expression of APM components utilizing RT-PCR and Western blot analyses. A heterogeneous expression pattern of MHC class I antigens, TAP peptide transporter, proteasome subunits, proteasome activator PA28 and the chaperones calnexin, calreticulin as well as tapasin was displayed by these tumor cell lines. Single or combined deficiencies in the expression and/or function of TAP, LMP2, LMP10 and tapasin were demonstrated in 11 of 12 cell lines studied, whereas the expression of calnexin, calreticulin, beta2-microglobulin, LMP7 and PA28alpha was unaltered or only weakly decreased. The impaired expression of TAP, LMP subunits and tapasin was not associated with altered ras, but resulted in reduced MHC class I surface expression. In particular, a significant allele- and locus-specific downregulation of the HLA-A and HLA-B haplotypes was found. IFN-gamma treatment corrected the TAP, LMP and tapasin deficiencies and enhanced the constitutive PA28alpha, LMP7, calnexin and calreticulin expression which was accompanied with increased levels of MHC class I antigens. Thus, dysregulation rather than structural alterations of different APM components might be one mechanism of colon carcinoma, small cell lung carcinoma and pancreatic carcinoma cell lines to evade immune recognition.
Delp
K
K
The Johannes Gutenberg-University, IIIrd Department of Internal Medicine, Mainz, Germany.
Momburg
F
F
Hilmes
C
C
Huber
C
C
Seliger
B
B
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects / Q000235:genetics; D001483:Base Sequence; D003546:Cysteine Endopeptidases; D017931:DNA Primers / Q000235:genetics; D015870:Gene Expression; D011905:Genes, ras; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D051379:Mice; D009097:Multienzyme Complexes; D009154:Mutation; D009375:Neoplasms, Glandular and Epithelial / Q000235:genetics / Q000276:immunology*; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins; D014407:Tumor Cells, Cultured
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters; D017931:DNA Primers; D015395:Histocompatibility Antigens Class I; D009097:Multienzyme Complexes; D011506:Proteins; D011994:Recombinant Proteins; C073119:TAP1 protein, human; C486171:Tap1 protein, mouse; C489516:Tap2 protein, mouse; C071313:LMP-2 protein; C071692:TAP2 protein, human; D007371:Interferon-gamma; D003546:Cysteine Endopeptidases; C077436:LMP7 protein; D046988:Proteasome Endopeptidase Complex