EXPRESSION OF TIE2 TEK IN BREAST-TUMOR VASCULATURE PROVIDES A NEW MARKER FOR EVALUATION OF TUMOR ANGIOGENESIS/

Endothelial receptor tyrosine kinases may play important roles in path ological vascular growth, particularly in tumours. In this study, immu nohistochemistry was used to evaluate the expression of a novel endoth elial receptor tyrosine kinase, Tie2/Tek, in the endothelium of vascul ar 'hotspots' in normal breast tissue (n = 10), benign breast lesions (n = 10) and in breast tumours (n = 123). Tie2 expression was detected in the endothelium of all breast tissues examined. However, the stron gest expression of ?Tie-2 was seen in vascular 'hot spots' within the inflammatory infiltrate at the periphery of invasive tumours. Moreover , the proportion of Tie2-positive vessels (Tie2 counts/CD31 counts) wa s significantly higher in breast tumours than the proportion of Tie2-p ositive vessels in either normal breast tissue or benign breast lesion s (P = 0.004 and 0.0001 respectively). These data are consistent with a role for Tie2 in tumour angiogenesis and demonstrate the potential u se of Tie2 expression as a novel marker of the tumour vasculature.