Differential distribution of tenascin in the normal, hyperplastic, and neoplastic breast

We studied by immunohistochemistry the distribution of tenascin with the monoclonal antibody 100EB2, and compared it with that of laminin in breast tissue samples from fetal, adult resting, lactating, and aging parenchyma, variants of fibrocystic disease, fibroadenomas, cystosarcoma phylloides, and ductal and lobular carcinomas. Monoclonal antibodies were applied to cryosections by the avidin-biotin-complex method; selected samples were studied by double immunofluorescence, and by Western blot analysis. In adult resting and aging breasts, tenascin immunoreactivity was noted in the periductal and periacinar stromal regions as thin irregular bands; in the lactating breast, broader periductal bands were observed. In these samples, laminin immunoreactivity was a single continuous line around ducts, acini, and vessels. In fetal breasts, tenascin appeared as thick periductal bands, whereas laminin remained as a delicate single line. In FCD, tenascin increased around ducts showing hyperplasia, papillomas and apocrine metaplasia, whereas laminin retained its delicate linear pattern. Similar patterns were seen in fibroadenomas and cystosarcoma phylloides with variable tenascin reactivity in the stroma beyond the ducts. Tenascin immunoreactivity was markedly increased around ducts containing in situ carcinoma appearing as broad bands, whereas that of laminin showed a linear, frequently discontinuous appearance. Prominent stromal tenascin immunoreactivity was seen in infiltrating ductal and lobular carcinomas, whereas laminin was virtually absent save for scattered lines. The abundance of tenascin in the carcinomatous stroma contrasted with its scarcity in the non-neoplastic stromal regions. By Western blotting, both chains of tenascin with molecular weights 250,000 and 180,000 were shown in ductal and lobular carcinomas as well as in normal breast. Tenascin immunoreactivity was noted in the periepithelial stromal regions of adult resting and aging breast ducts and acini. The amount of tenascin was moderately enhanced in certain physiologic conditions (fetal growth, gestation), as well as hyperplasias, dysplasias (fibrocystic disease) and benign tumors, whereas it was markedly enhanced in intraductal and infiltrating carcinomas. During fetal mammary development, adult physiologic and pathologic hyperplasias, and in carcinomas, the increasing tenascin reactivity contrasted with the stable or decreasing laminin reactivity.