Identification of transformation-related antigen by monoclonal antibody on Swiss 3T3 cells induced by transfection with murine cultured colon 36 tumor DNA.

The cell surface antigen associated with the transformed state of cells that could grow in an anchorage-independent manner was analyzed by use of techniques of DNA transfection and hybridomas secreting the monoclonal antibody (MoAb). Spleen cells of C57BL/6 mice immunized with a highly tumorigenic, chemically induced murine cultured colon 36 tumor (C-C36) of BALB/c origin were hybridized with NS-1, a hypoxanthine phosphoribosyltransferase-deficient myeloma line of BALB/c mice. Screening of hybridomas revealed an antibody that reacted with C-C36 and transformed Swiss 3T3 cells growing in soft agar after transfection of 3T3 cells with C-C36 DNA. The hybridomas that did not react with nontransformed 3T3 and the less tumorigenic BALB/c hemangioendothelioma line D10 were then selected. An MoAb was designated "#71295." This MoAb immunoprecipitated the antigen that consisted of 65,000- and 14,000-molecular-weight components with soluble C-C36 membrane antigens. It also reacted with 2 other chemically induced syngeneic colon tumor lines, cultured colon 26 tumor line and cultured colon 51 tumor line, and with fibrosarcoma Meth A. However, #71295 was not found in NS-1, D14, and BALB/c normal thymus, liver, colon, and kidney tissues. In addition, this MoAb could not inhibit the anchorage-independent growth of C-C36 and transformed 3T3 cells. These results suggest that although the molecule defined by #71295 might not be associated with the anchorage independence of cell growth, it could be a newly expressed determinant on the cell surface that is related to the events of cell transformation.