Lack of specificity of endoglin expression for tumor blood vessels

Enrica Balza, Patrizia Castellani, Andries Zijlstra, Dario Neri, Luciano Zardi, Annalisa Siri

Research output: Contribution to journalArticlepeer-review


A monoclonal antibody (MAb; A11) has been raised following mouse immunization with cultured human microvascular endothelial cells. The MAb showed a strong positivity within tumor vessels in glioblastoma and breast carcinoma samples, and the distribution was consistent with antigen association with vascular endothelial cells. A purification procedure of the antigen was developed starting from DG-RSV-LT-2, an immortalized human endothelial cell line. Molecular mass, N-terminal sequence of the purified antigen and localization on endothelial cell surface allowed identification with human endoglin (CD105). Flow cytometry analysis of a group of normal and transformed cell lines showed that, besides endothelial cells and myelocytic leukemia cells already shown to be positive, fetal fibroblasts, choriocarcinoma, fibrosarcoma and rhabdomyosarcoma cell lines were also positive for this antigen. Immunohistochemic analysis of several normal adult tissues revealed a more extensive presence of the antigen in normal vessels compared to that described with previously characterized antibodies. In fact, even though the staining was weaker than in tumor tissues, all tissues were found to be positive, at least in microvessels, except for normal breast. Moreover, in some tissues (glands and reproductive tract) a positive reaction was observed in the stroma. Since endoglin has been proposed as a possible target for antiangiogenic therapy in tumor patients and our data demonstrate a sizable amount of endoglin in normal vessels and stroma, its clinical use should be carefully reevaluated.

Original languageEnglish
Pages (from-to)579-585
Number of pages7
JournalInternational Journal of Cancer
Issue number4
Publication statusPublished - Nov 15 2001


  • Endoglin
  • Normal vessels
  • Stroma
  • Tumor vessels

ASJC Scopus subject areas

  • Cancer Research
  • Oncology


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