Linked Life Data

9216736

Source:http://linkedlifedata.com/resource/pubmed/id/9216736

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
1997-8-1
pubmed:abstractText
The transporter associated with antigen processing (TAP) complex is a heterodimeric transmembrane pump consisting of the TAP-1 and TAP-2 subunits; these subunits translocate peptides from the cytoplasm into the lumen of the endoplasmic reticulum, where they bind nascent major histocompatibility complex (MHC) class I molecules. Loss or reduced expression of the TAP genes results in the synthesis of unstable peptide free MHC class I molecules that are only weakly expressed on the cell surface. In a number of human tumor cell lines, downregulation of MHC class I expression has been found to be associated with reduced or absent TAP expression. To investigate whether alterations in MHC class I expression occur during transformation and subsequent progression and whether MHC class I suppression is caused by impaired TAP function, we analyzed the protein expression of MHC class I heavy and light chain and TAP-1 in three renal cell carcinoma (RCC) cell lines and short-term cultures from corresponding normal kidney tissue. In one case a cell line established from a metastatic lesion was also available. Compared with normal epithelial cells, suppression of TAP-1 and MHC class I molecules was detected in all three primary RCC cells and was even more pronounced in the metastatic cell line. In contrast to normal epithelial cells, MHC class I membrane expression of two RCC lines was enhanced by culture in the presence of MHC class I binding peptides or at low temperature (26 degrees C) instead of 37 degrees C. Unstable MHC class I surface expression is caused by dissociation of the MHC class I heavy and light chain molecules as a result of functional defects in the antigen processing machinery, e.g., impaired peptide transport. Attempts to counteract the reduced immunogenicity by transferring the TAP genes into these cells demonstrated that TAP-1-modified RCC cells expressed higher levels of MHC class I molecules. These data indicate that downregulation and instability of MHC class I surface expression in RCC cells is at least partially caused by deficient loading with endogenous peptides and can be restored by TAP gene transfer.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0301-472X
pubmed:author
pubmed:issnType
Print
pubmed:volume
25
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
608-14
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Expression and function of the peptide transporters in escape variants of human renal cell carcinomas.
pubmed:affiliation
Johannes Gutenberg-Universität, Abteilung für Hämatologie/Onkologie, Mainz, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't