Inappropriate production of collagen and prolyl hydroxylase by human breast cancer cells in vivo.

Thirty-two scirrhous cancers of breast have been examined to determine the origin of the collagen stroma in these tumours. Employing two immunohistochemical techniques it has been shown that the malignant epithelial cells in 30 of these tumours contain not only collagen but also prolyl hydroxylase, a key enzyme in collagen biosynthesis. Neither this enzyme nor collagen was detectable in the spindle cells in the stroma of these tumours. Neither the epithelium in normal breast, that in fibrocystic disease and in fibroadenomata, nor the malignant epithelium in two medullary cancers of breast contained either collagen or prolyl hydroxylase. These results strongly suggest that the malignant epithelium of scirrhous breast cancers produces its own collagen stroma and that the scirrhous reaction in these tumours is not a host response to tumour invasion. The production of collagen and prolyl hydroxylase by breast cancer cells (of the scirrhous type) therefore represents another example of inappropriate protein production by a human tumour.