INCREASED EXPRESSION OF HUMAN HISTOCOMPATIBILITY LEUKOCYTE ANTIGEN-G IN COLORECTAL-CANCER CELLS

Human histocompatibility leukocyte antigen (HLA)-G is a nonclassical m ajor histocompatibility complex class I molecule. HLA-G is known to pr ovide tolerance from recognition by natural killer cells. We studied H LA-G expression in 39 human colorectal cancers and 23 extra-neoplastic colon tissue samples by RT-PCR. The expression of HLA-G mRNA was sign ificantly more frequent in colorectal cancer (34 of 39 cases) than in the extraneoplastic tissue (10 of 23 specimens; chi(2) test, p=0.0003) . HLA-G expression was also confirmed on the cancer cells immunohistoc hemically. These results suggested that HLA-G on colorectal cancer cel ls may be correlated with escape from immunological surveillance durin g colon cancer development.