Connective tissue growth factor expression in pediatric myofibroblastic tumors

Human connective tissue growth factor (CTGF) is a secreted cysteine-rich peptide and a member of the peptide family that includes serum-induced immediate gene products such as a v-src-induced peptide and a putative proto-oncogene, c-src. CTGF is secreted by endothelial cells, fibroblasts, smooth muscle cells, and myofibroblasts. Its expression is increased in various human and animal fibrotic diseases. We hypothesized that tumors with significant fibrous and vascular components would exhibit increased expression of CTGF. We examined the expression of CTGF mRNA by in situ hybridization in 12 pediatric tumors and tumor-like conditions, including angiofibroma, malignant fibrous histiocytoma, infantile myofibromatosis, and malignant hemangiopericytoma. All the tumors showed moderate to intense CTGF expression in tumor cells and/or endothelial cells of the associated vasculature. Angiofibromas expressed CTGF only in factor VIII-positive endothelial cells and vascular smooth muscle cells. In contrast, infantile myofibromatosis, malignant hemangiopericytomas, and fibrous histiocytomas expressed CTGF in both endothelial cells and in vimentin-positive tumor cells, particularly those around the blood vessels. CTGF mRNA was not detected in the inflammatory cells observed in many of the tumors. The presence of CTGF in the endothelial cells and tumor cells around blood vessels raises the possibility that CTGF is involved in the pathogenesis of these myofibroblastic tumors.