Objective: Human leukocyte antigen-G (HLA-G) is a nonclassical major histocompatibility complex (MHC) molecule with highly limited tissue distribution that has been proposed to protect tumor cells from natural killer cell lysis. To delineate the potential role of HLA-G in ovarian cancer, we investigated expression patterns of this molecule in human ovarian cancer cell lines and tissues.
Methods: HLA-G expression was determined both at RNA level by reverse transcriptase-polymerase chain reaction (RT-PCR) and protein level by Western blotting and immunohistochemistry using monoclonal antibody against denatured heavy chain of HLA-G, MEM-G1, in 13 ovarian cancer patient tissues and 6 ovarian cancer cell lines (OVCAR-3, SKOV-3, ES-2, PA-1, TOV-112D, TOV-21G).
Results: We found mRNA transcripts of different HLA-G isoforms in five of 6 ovarian cancer cell lines (OVCAR-3, SKOV-3, ES-2, TOV-112D, TOV-21G). HLA-G protein was also detected in 5 cell lines that exhibited expression of HLA-G mRNA transcripts. Immunohistochemical analysis of human ovarian cancers revealed expression of HLA-G in eight of 13 tissue samples.
Conclusion: Our results provide additional clues as to how a tumor can be selected in vitro and in vivo to escape from cytotoxic anti-tumor responses. We suggest that the aberrant expression of HLA-G may contribute to immune escape in human ovarian cancer.
|