TRANSFECTION OF TAP-1 GENE RESTORES HLA CLASS-I EXPRESSION IN HUMAN SMALL-CELL LUNG-CARCINOMA

HLA class 1 antigens of the human major histocompatibility complex (MH C) play an important role in immune response. Consistent with their ro le in immune surveillance, these antigens are expressed on most cell t ypes. However, a marked deficiency or lack of expression of these anti gens has been observed in a variety of human neoplasms. We have shown that a number of class 1-deficient human tumor cell lines, including s mall cell lung carcinoma, lacked products of MHC-encoded TAP1 and LMP2 genes. Since a direct evidence for the role of these genes in class 1 expression in tumor cells is not available, in the present study we t ransfected class 1-deficient human small-cell lung carcinoma cells wit h cDNAs corresponding to TAP1 gene and to LMP2 gene, Following transfe ction, tumor cells expressed products of the respective transfected ge ne. Cell-surface expression of class 1 molecules was, however, observe d in cells transfected with TAP1, but not in tumor cells transfected w ith LMP2 gene. Our results provide conclusive evidence for a role of T AP1 gene in class 1 expression and suggest that transfection of TAP ge nes may be useful to upregulate class 1 expression in tumor cells. Thi s strategy for restoration of class 1 expression by transfection of TA P genes is relevant for tumor rejection and/or abrogation of metastase s formation. (C) 1998 Wiley-Liss, Inc.