Expression of VLA-2, VLA-3, and alpha(v) integrin receptors in uveal melanoma: association with microvascular architecture of the tumour and prognostic value

Background-The interaction of the integrin receptors with their ligands (co llagen, laminin, fibronectin, and others) has a crucial role during the reo rganisation of the extracellular matrix and the metastatic process. The pre sence of particular vascular patterns in uveal melanoma is associated with the development of metastases. There is some evidence that interactions bet ween the tumour cells and the extracellular matrix are responsible for the shape of these patterns. Methods-The expression of VLA-2, VLA-3, and alpha(V) integrin receptors was examined by immunohistochemistry on paraffin embedded tumour specimens fro m 92 uveal melanomas (iris melanomas excluded). Possible correlations betwe en these results and the tumour vascular patterns, the histological feature s of the tumours as well as the clinical outcome of the patients, were inve stigated. Results-The expression of VLA-2 in tumours was associated with the presence of vascular networks (p = 0.05). Tumours with less than 25% VLA-3 positive cells infiltrated the sclera more frequently than those with more than 25% VLA-3 cell positivity (p = 0.05). Tumours expressing less than 50% alpha(V ) positive cells were associated with the mixed or epithelioid cell type (p = 0.05) and, with less statistical precision, with the presence of extraoc ular growth (p = 0.07). The univariate logistic regression analysis showed that the risk of developing metastases within the first 5 years after diagn osis did not depend on the expression of the integrin receptors investigate d. Conclusion-The potential biological importance of the associations between integrin expression and the histopathological features of the tumours found in the present study remains to be elucidated in future experiments. The i mmunohistochemical detection of VLA-2, VLA-3, and alpha(V) integrins had no prognostic value in our preliminary report.