ENDOGLIN (CD105) EXPRESSION IN NONNEOPLASTIC AND NEOPLASTIC HUMAN TISSUES AND HUMAN CANCER CELL-LINES

Endoglin is an integral membrane glycoprotein that binds TGF-beta(1,3) with high affinity and is thought to play an important role in modula ting the interaction of TGF-beta with its cell surface receptors. In t his study a recently characterized monoclonal antibody (29-G8) recogni zing endoglin was used to examine expression in a variety of human tis sues and human cancer cell lines. Formalin-fixed, paraffin-embedded se ctions were examined by light microscopy and cell lines were analyzed by now cytometry. Immunostaining was noted in a variety of non-neoplas tic epithelia from different organs; most of the neoplastic tissues su rveyed also demonstrated prominent immunoreactivity for 29-G8. Flow cy tometric analysis of the cell lines revealed strong 29-G8 immunoreacti vity in almost all lines examined. Our results suggest that endoglin e xpression is much more ubiquitous than was previously thought and that endoglin may play a role in modulating TGF-beta binding activity in a variety of normal and neoplastic human tissues.