DISTRIBUTION OF TENASCIN, CELLULAR FIBRONECTINS AND INTEGRINS IN THE NORMAL, HYPERPLASTIC AND NEOPLASTIC BREAST

We present immunolocalization data on tenascin (Ten), and extradomains A and B (EDA-, EDB-) and oncofetal (Onc-) isoforms of cellular fibron ectin (cFn), and alpha1-6 and alpha(v) and beta1-4 integrin subunits o n cryosections of normal human breast, the spectrum of fibrocystic dis ease (FCD), and benign and malignant breast neoplasms. Fetal breast du cts were surrounded by broad Ten bands; adult breast ducts and acini w ere encompassed by thin continuous rims. In FCD, Ten was detectable an d was clearly enhanced around hyperplastic ducts. Fibroadenomas showed uneven Ten periductal reactions while in all carcinomas, the stroma s howed extensive and strong reactions that were most intense at the tum ors' invasive edge. EDA-cFn's distribution was similar to Ten's but th e staining was stronger while EDB- and Onc-cFn were virtually restrict ed to fetal breasts and carcinomas. In the normal adult breast, alpha1 ,2,3 and alpha6, and B1 and beta4 integrins were detected in myoepithe lial cells; weaker staining was also noted in the basolateral aspect o f luminal cells; this profile was retained - and at times enhanced - i n FCD, fibroadenomas and in situ carcinomas in which myoepithelial ele ments were present. In carcinomas, particularly in those of high grade , integrins tended to be reduced. However, mucinous carcinomas showed enhanced expression and the emergence of alpha5, integrin that was not in the normal repertory; also a subset of infiltrating lobular carcin omas showed prominent alpha1 and alpha6 and beta1 and - rarely - beta4 staining distributed in delicate cytoplasmic processes (kinetopodia). These data indicate that the complex cell-matrix and cell-cell intera ctions of the normal breast are slightly altered in hyperplastic proce sses and benign neoplasms whereas profound chances occur in carcinomas . The latter display enhanced Ten and EDA- and Onc-cFn expression in p articular, while most integrins appear decreased. Notably, mucinous an d some lobular carcinomas display enhancement of certain integrins. Th e conspicuous localization of integrins in kinetopodia may be signific ant in relation to the invasive behavior of lobular carcinomas.