Pg. Natali et al., EXPRESSION OF FIBRONECTIN, FIBRONECTIN ISOFORMS AND INTEGRIN RECEPTORS IN MELANOCYTIC LESIONS, British Journal of Cancer, 71(6), 1995, pp. 1243-1247
In vitro studies have demonstrated that fibronectin (FN) can deliver a
mitogenic signal to quiescent human melanoma cells and that the alpha
(5)/beta(1)-integrin receptor mediates this stimulus. In view of this
finding we have analysed the in vivo expression of FN, and of ED-A and
ED-B FN isoforms, in benign and malignant lesions of melanocyte origi
n. In the same specimens the expression of fibronectin integrin recept
ors was evaluated. The results demonstrate that, while detection of FN
does not correlate with transformation and tumour progression, the ex
pression of the two isoforms is associated with transformation and tha
t only the ED-A variant is found in metastases. Integrin phenotpping d
isclosed that alpha(3)/beta(1) expression is associated with tumour pr
ogression, alpha(v)/beta(3) is a marker of transformation, alpha(4) is
rarely expressed and alpha(5) is expressed by about 50% and 30% of th
e primary and metastatic lesions respectively. Taken together, the res
ults of this study demonstrate that transformation and tumour progress
ion of the melanocyte lineage are associated with modulation of expres
sion of FN isoforms and FN integrin receptors. Furthermore, the expres
sion of alpha(5)-integrin in a considerable percentage of primary and
metastatic lesions indicates that FN may deliver a proliferative stimu
lus to melanoma cells in vivo.