B. Bier et al., IMMUNOHISTOCHEMICAL DEMONSTRATION OF METALLOTHIONEIN IN NORMAL HUMAN BREAST-TISSUE AND BENIGN AND MALIGNANT BREAST-LESIONS, Breast cancer research and treatment, 30(3), 1994, pp. 213-221
Metallothioneins (MTs) are a set of low molecular weight proteins with
a high binding affinity to metal ions. MT over-expression has been re
cently demonstrated in invasive ductal carcinoma of the breast with po
or clinical prognosis. In the present study, MTs have been immunohisto
chemically investigated in normal human breast tissue and a variety of
benign, pre-invasive, and malignant breast lesions. Tn normal breast
tissue, MTs were present in myoepithelial cells whereas the vast major
ity of luminal cells were MT negative. In lesions without increased ca
ncer risk (adenosis and scleradenosis), MT was only immunolocalized in
myoepithelial cells. In papillomas, MT was also found exclusively in
myoepithelial cells. In most cases of epitheliosis, both the luminal a
nd myoepithelial cells expressed MT. Atypical lobular hyperplasia,lobu
lar carcinoma in situ, and 13/15 invasive lobular carcinomas showed no
MT over-expression. The two invasive lobular carcinomas with MT over-
expression were classified as pleomorphic lobular carcinomas with apoc
rine differentiation. In contrast to lobular cancerization, 12/24 duct
al in situ carcinomas and 9/20 invasive ductal carcinomas showed MT ov
er-expression. In situ components found within invasive ductal carcino
mas usually reflected the MT status of their invasive counterpart. It
is concluded from our immunohistochemical results that breast carcinom
a cases with MT overexpression arise from lesions which also show MT o
verexpression. Thus MT expression in carcinomas may be regarded as a g
enuine feature of the tumour cells and seems not to be related to endo
genous or exogenous factors known to induce MT synthesis.