[Immuno histochemical study of endothelin-1 in breast cancer]

Endothelin-1 (ET-1) content was measured in tissue sections from 42 human breast cancer from grade 1 to grade III and from 8 normal breast tissue by immunohistochemistry and image analysis methods. The ET-1 was stained as brownish grains localized in the cytoplasm of tumor cells and normal breast epithelial cells. However, both the proportion of ET-1 positive cells and ET-1 cellular content were significantly higher in cancer cells than in normal breast epithelium. Moreover, the ET-1 content in the tumor cells was inversely correlated with the degree of tumor cell differentiation. It is suggested that ET-1 is synthesized by human breast cancer and its over expression may induce an abnormal proliferation of breast tissue and result in malignant growth.