Modification of histocompatibility antigen expression in cells expressing activated oncogenes: implications for tumour development.
The down-regulation of major histocompatibility complex (MHC) antigen expression which occurs in tumours may be an important element in tumour progression - the increasing malignancy of tumours - which is so much a feature of cancer - if it allowed the avoidance of T-cell immunity. Obviously, this downregulation could be due to a wide variety of mechanisms. An interesting possibility is that some oncogenes may directly influence MHC gene expression, perhaps at several different levels. The way in which oncogenes work-through signal transduction and transcription controls-suggests how this could happen. Three examples of oncogenes for which there is evidence that there expression modulates MHC gene expression are adenovirus EIA, myc and ras.