The role of the integrin family of adhesion molecules in the development of tumors metastatic to the orbit.

Tumors metastatic to the orbit frequently originate from certain primary tumors such as breast, lung, prostate, and melanoma. The site-specific nature of orbital metastases, as well as that of other metastatic lesions, cannot be the result of random seeding. We present evidence from a review of the literature demonstrating that tumor cells express adhesion molecules of the integrin family, and that these receptors play a pivotal role in the development of a metastatic colony. We investigated orbital metastatic lesions from prostate carcinoma, malignant melanoma, and lobular breast carcinoma to determine the level of integrin expression by immunohistochemistry. Several integrin subunits (alpha2, alpha4, beta3) were found to have increased expression in the metastasis when compared to normal prostate tissue and normal melanocytes. The increased expression of these integrins may be responsible for the tendency of these tumors to metastasize to the orbit, as well as for the tendency of prostate tumors to metastasize to bone. The results from the staining of the breast metastasis were inconclusive.