Bio-histochemical aspects of integrins (α2β1, α6β1) in invasive mammary carcinomas: An immunohistochemical study

Immunohistochemical expression of integrins was examined in 39 human invasive mammary carcinomas, of which 34.2% and 43.6% expressed integrins α2β1 and α6β1, respectively. Immuno-electron microscopy clearly demonstrated that the integrins were in the cell membrane of the carcinoma cells. Similar expression of integrin α2β1 or α6β1 in both the intraductal component and invasive portion of the same tumor was seen in 76.9% and 85.7% of cases, respectively. This suggested that invasive carcinoma cells retained their integrin expression after invasion through the basement membrane. Reciprocal expression of integrins α2β1 and α6β1 was seen in 20 cases. Expression of α2β1 was seen significantly less frequently in scirrhous carcinoma than in the more differentiated papillotubular or solid tubular carcinoma (Chi-squared test, P < 0.05). Intraductal components of carcinoma were present more frequently in cases expressing integrin α2β1 than in those that were negative. This suggests the potential usefulness of integrins as clinical parameters in the surgical treatment of mammary carcinomas, since recent trials of conservative treatment for mammary carcinoma have focused on the intraductal spread of the tumor cells.