ENHANCED EXPRESSION OF METALLOTHIONEIN IN HUMAN NON-SMALL-CELL LUNG CARCINOMAS FOLLOWING CHEMOTHERAPY

Metallothioneins (MTs) are induced by various stimuli and probably con fer drug resistance in tumor cells in vitro. To investigate whether MT expression in lung cancer is induced by chemotherapy, ninety-seven su rgical specimens from patients who had or not received chemotherapy co ntaining cisplatin, were stained immunohistochemically for MT. In untr eated tumors, 23% (15/64) of all tumors and 27% (15/56) of non-small-c ell carcinoma (NSCLC) stained positive, while all eight small-cell car cinoma (SCLC) were negative. In treated tumors, 52% (17/33) of all tum ors, 80% (12/15) of NSCLC and 28% (5/18) of SCLC stained positive. The proportion of positively-stained rumors was significantly higher in t reated NSCLC compared with untreated NSCLC (P = 0.0005) and treated SC LC (P<0.005). Our results indicate that MT expression ina eases follow ing chemotherapy and that such expression may confer drug resistance i n lung cancer, especially NSCLC.