Immunohistochemical localization of metallothionein in endometrial lesions

Metallothioneins (MTs) are a group of ubiquitous low-molecular-weight prote ins essential for the protection of cells against heavy metal ion toxicity. The immunohistochemical expression of MT was studied by immunohistochemist ry using a monoclonal antibody (E9) against a conserved epitope of I and II isoforms in a series of 89 endometrial carcinomas, 34 cases of hyperplasia , and 32 samples of normal endometrium, In secretory phase endometrium, ext ensive MT expression was detected in most cases (92.4%), In contrast, MT im munoreactivity was confined to small foci in 22.2% of proliferative phase c ases. The MT values in normal endometrium were inversely correlated with oe strogen receptor (ER) content (p<0.0001), progesterone receptor (PgR) conte nt and with PCNA (p<0.0001) and MIB1 (p=0.001) scores. In hyperplastic lesi ons, MT expression was detected only in 3.3% of cases, while in the group o f carcinomas it was observed in 23.1%, A statistically significant differen ce of MT expression was observed between carcinomas and simple hyperplasias (p=0.03). In carcinomas, MT expression was positively correlated with grad e (p=0.0065), MIB1 (p=0.022), and p53 (p=0.006) expression, and inversely w ith PgR (p=0.03). A trend of inverse correlation between MT and ER receptor was also detected (p=0.07), These data suggest that MT expression seems to be under hormonal control in normal endometrium; that it may modify p53 ex pression; and that it could be used as an additional biological marker indi cating aggressive behaviour in endometrial lesions. Copyright (C) 2000 John Wiley & Sons, Ltd.