Metallothionein expression in carcinoma of the gallbladder.

Metallothioneins (MT) are sulphur-rich, low molecular-weight, intracellular metal-binding proteins with a possible role in carcinogenesis of some human tumours. Metallothionein expression in gallbladder cancer has not been studied previously. Immunohistochemical expression of metallothionein was studied in 42 gallbladders (27 cases of carcinoma of the gallbladder, eight chronic cholecystitis and seven cases of normal gallbladder). Metallothionein expression was significantly higher in cases with carcinoma of the gallbladder (70.37%) as compared to chronic cholecystitis (25%) and normal gallbladders (0%). There was a trend suggestive of increasing MT expression with increasing histological dedifferentiation of carcinoma of the gallbladder. The increased expression of MT in cases of carcinoma of the gallbladder may represent an increased exposure to heavy metals, which are known carcinogens, and may have a role in gallbladder carcinogenesis. Metallothionein over-expression in carcinoma of the gallbladder may be relevant to the poor prognosis and chemoresistance seen in these cases.