The integrin VLA‐2 as a collagen receptor and VLA‐5 as a fibronectin receptor were detected immunohistochemically in normal, benign tumor and carcinoma tissues of the breast. Both proteins were also detected by Western‐blot analysis in some carcinoma cases. Epithelial and myoepitheiial cells of both normal breast and benign tumor were in all cases immunoreactive for VLA‐2 in the plasma membrane. Carcinoma cells in the invasive component were not immunoreactive for VLA‐2 in 31 (46%) of 67 cases. Carcinoma cells in the intraductal components were negative for VLA‐2 in only 4 (11%) of 36 cases, while 20 cases (56%) showed weak expression and 12 cases (33%) showed strong expression. Metastatic carcinoma cells in the lymph nodes of 6 cases showed no immunoreactivity except in one case, whereas, again with the exception of one case, the carcinoma cells in the primary tumors did show VLA‐2 expression. With regard to VLA‐5, there was no difference in its expression in the invasive components and the intraductal components. These findings suggest that the loss of VLA‐2 plays a role in the invasion and metastasis of breast carcinoma.
A case of myxoma of the breast is reported. The patient, a 19 year old Japanese woman, showed a lump in the left breast which had enlarged gradually over 3 years. A tumor measuring 5 × 5 × 4.5 cm was located mainly in the mammary parenchyma, but partially involved the overlying subcutaneous tissue. Histologically the tumor was multinodular and each nodule consisted of an abundant myxoid substance with a few spindle or stellate mesenchymal cells. The presence of hyaluronic acid was observed in the myxoid area, and a few constituent cells showed Immunoreactivitiesfor S‐100 protein and α1‐antichymotrypsin. Electron microscopic studies revealed that some constituent cells looked like undifferentiated mesenchymal cells, while others showed a differentiation similar to fibroblast or histiocyte. These findings suggest that the constituent cells might derive from totlpotential primitive mesenchymal cells.
The integrin VLA‐6 as a laminin receptor and laminin as a ligand for laminin receptor were detected immunohisto‐chemically in normal, benign tumor and carcinoma tissues of the breast. Epithelial cells of both normal breast and benign tumor were in almost all cases strongly immuno‐reactive for VLA‐6 in the plasma membrane. Carcinoma cells in 34 of 70 cases (49%) with an invasive component were not immunoreactive for VLA‐6, and no carcinoma ceils showed strong positivity. Although carcinoma cells in only four of 51 cases (8%) with intraductal components were negative for VLA‐6, 37 cases (72%) showed weak expression of VLA‐6 and 10 cases (20%) showed strong expression of VLA‐6. A concordant expression of VLA‐6 on carcinoma cells and laminin around carcinoma cell nests with an invasive component was observed, and VLA‐6 expression in carcinoma cells was correlated to tubular formation in carcinoma cell nests as an indicator of differentiation. These findings suggest that loss of VLA‐6 plays a role in the invasion of breast carcinoma, and that VLA‐6 laminin receptor and laminin may contribute to tubular differentiation of breast carcinoma cells.
Epithelial hyperplasia in the duct, ductule or lobule of the breast is a very common lesion and has been considered to carry a risk of subsequent invasive carcinoma. However, it is not known whether epithelial hyperplasia can transform into carcinoma or whether malignant change occurs de novo. We analyzed the incidence of epithelial hyperplasia of the breast by making a comparison between cases of breast carcinoma and control autopsy specimens, and studied differences in the membrane antigens of the constituent cells using immunohistochemical staining of blood group antigens. It was found that the frequency of epithelial hyperplasia was higher in the cases of breast carcinoma. The lesions showed loss of A, B and H antigens at high frequency, and the proportion of lesions showing loss of these antigens became higher as the atypia of the lesion increased. On the other hand, expression of Lea antigen was observed more frequently in atypical epithelial hyperplasia or in situ carcinoma than in ordinary epithelial hyperplasia. These findings suggest possible transformation from epithelial hyperplasia to carcinoma, and indicate that atypical epithelial hyperplasia may be precancerous in nature. Acta Pathol Jpn 42: 193–200, 1992.
Laminin, type IV collagen and fibronectin were examined immunohistochemically in the invasive component of breast carcinomas. Laminin was expressed around the invasive carcinoma cell nests in 38 (54%) of 71 cases. Immunoreactivity for type IV collagen was observed around the invasive carcinoma cell nests or the stroma apart from carcinoma cells in 44 (80%) of 55 cases. Fibronectin was strongly expressed in the stroma only in 75 (99%) of 76 cases.The expression of laminin significantly correlated with tubular formation in the invasive carcinoma cell nests and showed a tendency to be correlative to estrogen receptor (ER) and progesterone receptor (PgR) of carcinoma tissue, but no correlation among laminin expression, histological type, the age of patients, tumor size and lymph node metastasis was noted. Type IV collagen and fibronectin did not correlate to any clinicopathological factors such as histological type, grade of differentiation, the age of patients, tumor size, lymph node metastasis, ER and PgR status. No concordant expression of these extracellular matrices was seen.
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