Tumor cells frequently show a lack of surface class-I major histocompatibility complex (MHC) antigen expression. These molecules are key recognition structures for immune rejection of tumor cells and their absence at the surface of tumor cells could favor the progression of tumors. We have analyzed the transcriptional mechanisms that could lead to suppression of MHC-class-I expression in human tumor cell K562. The expression of MHC-class-I genes is highly controlled by regulatory factors interacting with an enhancer sequence upstream of MHC-class-I genes. In this report we show that DNA binding activity of 2 regulatory factors, KBF1 and NF-κB, known to be essential for constitutive expression of MHC-class-I genes, is deficient in nuclear extracts from K562 cells. Induction of class-I gene expression at the surface of tumor cells by interferon-γ (IFN-γ) and tumor necrosis factor α (TNF-α) shows that TNF-α can act in synergy with IFN-γ to induce DNA binding of both factors NF-κB and KBF1 to the class-I gene enhancer and that this induction of transcriptional factors is correlated with enhancement of MHC-class-I mRNA transcription and cell-surface antigen expression.
|Number of pages||8|
|Journal||International Journal of Cancer|
|Issue number||SUPPL. 6|
|Publication status||Published - 1991|
ASJC Scopus subject areas
- Cancer Research