Expression of glutathione S-transferase isoenzymes in human small cell lung cancer cell lines.

Abstract

A glutathione S-transferase (GST) isoenzyme having common antigenicity to rat placental form (GST-P) and human placental form (GST-pi) has recently been suggested may be a marker of carcinogenesis. In the present study we have investigated the expression of this isoenzyme in three small cell lung cancer cell lines in order to determine whether or not this isoenzyme can be used as a general marker of carcinogenesis. GST activity towards 1-chloro-2,4-dinitrobenzene in two of the cell lines (NES and NOC-361) was moderately higher than that in normal human lung, but this activity was markedly suppressed in one of the cell lines (NCI-H69). Quantitation of the GST isoenzymes in the tumors grown in nude mice by injecting these cell lines also revealed a moderate increase of GST-pi-type isoenzyme in NES and NOC-361 and its suppression in NCI-H69. Immunocytochemical localization studies with these tumors using antibodies raised against GST-pi also indicated a drastic decrease of GST-pi-type isoenzyme in NCI-H69 and this finding was confirmed by Western blot studies. These results suggest that GST-pi, or the isoenzyme(s) having similar immunological nature to GST-pi, cannot be used as the general markers of neoplastic states.