Metallothionein and apoptosis in primary human hepatocellular carcinoma and metastatic adenocarcinoma

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Abstract
Differences in expression of metallothionein (MT) have been reported in various human tumours. MT is mainly expressed in proliferating epithelial tumour cells but in human hepatocellular carcinoma (HCC) there is only a minimal expression of MT. Since MT is a zinc binding protein and certain inducers of MT including zinc play a role in apoptosis, studies were undertaken to compare the expression of MT and the presence of apoptotic cells (APPC) in both primary HCC and metastatic adenocarcinoma. Histological sections of 13 cases of primary HCC and eight cases of metastatic adenocarcinoma were obtained from archival samples. They were stained for MT using a polyclonal antibody which cross-reacts readily with human MT and for APPC by the TUNEL technique. Normal human liver had consistent MT staining with no detectable APPC. The primary HCC showed moderate MT staining with a small number of APPC while metastatic adenocarcinoma showed no MT staining with a large number of APPC. These results suggest a relationship between absence of MT and appearance of APPC in human liver tumours, especially in metastatic adenocarcinomas.