Angiogenesis and vascular architecture in pheochromocytomas: distinctive traits in malignant tumors.
Angiogenesis is a critical step in tumor growth and metastatic invasion. We here report the study of the vascular status of 10 benign and 9 malignant pheochromocytomas. We examined the vascular architecture after immunostaining endothelial cells (CD34) and vascular smooth muscle cells (alpha-actin) and identified a vascular pattern characteristic of malignant lesions. To define a gene expression profile indicative of the invasive phenotype, we studied by in situ hybridization the expression of genes encoding several pro- and anti-angiogenic factors [hypoxia-inducible factor (HIF-1 alpha), EPAS1, vascular endothelial growth factor (VEGF), VEGF receptors, angiopoietins and their receptor Tie2, five genes of the endothelin system, and thrombospondin 1]. A semiquantitative evaluation of the labeling revealed an induction of genes encoding EPAS1, VEGF, VEGFR-1, VEGFR-2, endothelin receptor, type B (ETB) and endothelin receptor, type A (ETA) in malignant pheochromocytomas as compared to benign tumors. These differences were observed in tumor cells, in endothelial cells, or in both. Quantification by real-time reverse-transcriptase polymerase chain reaction showed an increase of EPAS1, VEGF, and ETB transcripts of 4.5-, 3.5-, and 10-fold, respectively, in malignant versus benign tumors. Furthermore, we observed a strong correlation between the expression of EPAS1 and VEGF in tumoral tissue and between EPAS1 and ETB in endothelial cells. Altogether, our observations show that analysis of angiogenesis provides promising new criteria for the diagnosis of malignant pheochromocytomas.
D000199:Actins / Q000032:analysis; D000310:Adrenal Gland Neoplasms / Q000098:blood supply* / Q000473:pathology / Q000601:surgery; D000328:Adult; D000368:Aged; D018952:Antigens, CD34 / Q000032:analysis; D001483:Base Sequence; D015415:Biomarkers / Q000032:analysis; D017931:DNA Primers; D016228:Endothelial Growth Factors / Q000235:genetics; D004730:Endothelium, Vascular / Q000473:pathology; D005260:Female; D005819:Genetic Markers; D006133:Growth Substances / Q000235:genetics; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D008207:Lymphatic Metastasis / Q000235:genetics / Q000473:pathology; D008222:Lymphokines / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000473:pathology; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000473:pathology*; D010673:Pheochromocytoma / Q000098:blood supply* / Q000235:genetics / Q000473:pathology / Q000556:secondary; D040262:Receptors, Vascular Endothelial Growth Factor / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D000199:Actins; D018952:Antigens, CD34; D015415:Biomarkers; D017931:DNA Primers; D016228:Endothelial Growth Factors; D005819:Genetic Markers; D006133:Growth Substances; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D040262:Receptors, Vascular Endothelial Growth Factor