Characterization of gamma-glutamyltranspeptidase in murine cervical cancer by biochemical and immunological techniques.

Immunodiffusion, immunofluorescence, and flow cytometric techniques were used to characterize the expression of murine gamma-glutamyltranspeptidase (gamma GT) on normal and cervical cancer tissue. In immunodiffusion tests, the rabbit antiserum produced against highly purified murine kidney gamma GT formed two lines against normal kidney and one line with pancreas which fused with the major line of kidney. gamma GT purified by similar techniques from a murine cervical tumor produced a single line of identity with the kidney preparation, indicating that the gamma GT of the tumor was immunologically identical with normal enzyme. Both kidney and tumor gamma GT were labile to heating at 56 degrees, and neither enzyme was protected by dithiothreitol. Polyacrylamide gel electrophoresis indicated three components from the tumor material and four from the normal kidney. Both tissue sites expressed several isozymes which appeared to be antigenically identical. Biochemical methods indicated there was at least 50-fold more gamma GT in kidney than in tumor cells. In contrast, the level of membrane-associated gamma GT determined by flow cytometry was similar in the two cell types. Two-parameter flow cytometric analysis with DNA and antibody defined the presence of two proliferating gamma GT-positive tumor cell populations in the cervical tumor. Thus, although tumor and normal gamma GT are antigenically identical, the antisera can be combined with DNA and other markers to better describe tumor heterogeneity and progression.