Laboratory of Jeffrey Winkles Ph.D.
Core Facilities used: Flow Cytometry and Histology Cores
Soluble Tumor Necrosis Factor-Like Weak Inducer of Apoptosis Overexpression in HEK293 Cells Promotes Tumor Growth and Angiogenesis in Athymic Nude Mice
David H. Ho, Hong Vu, Sharron A. N. Brown, Patrick J. Donohue, Heather N. Hanscom and Jeffrey A. Winkles
Departments of Surgery and Physiology and the University of Maryland Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland
|Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a member of the tumor necrosis factor superfamily of structurally related cytokines. TWEAK acts on responsive cells via binding to a cell surface receptor named Fn14. Recent studies have demonstrated that TWEAK can stimulate numerous cellular responses including cell proliferation, migration, and proinflammatory molecule production. It has also been reported that TWEAK can stimulate blood vessel formation in the rat cornea angiogenesis assay, but it is presently unknown whether this cytokine could play a role in the pathological angiogenesis associated with human diseases such as cancer, rheumatoid arthritis, and diabetic retinopathy. In the present study we investigated whether TWEAK was expressed in human tumors and whether it could promote tumor growth and angiogenesis in vivo. TWEAK mRNA expression was detected in many tumor types by cDNA array hybridization analysis, and TWEAK protein expression was confirmed in human colon cancer tissue by immunohistochemistry. As an initial approach to address whether TWEAK might act as a tumor angiogenesis factor, we established several human embryonic kidney cell lines that constitutively secrete a soluble TWEAK protein and examined their growth properties in vitro and in vivo. We found that although TWEAK-overexpressing cells do not have a growth advantage in vitro, they form larger and more highly vascularized tumors in athymic mice when compared with control, vector-transfected cells. This result suggests that the TWEAK-Fn14 signaling system may be a potential regulator of human tumorigenesis.|
Effect of TWEAK overexpression on tumor vascularization. A. Photographs of representative tumors harvested from each of the four groups on day 14 are shown. B. Hemoglobin content was measured in tumors harvested from each of the four groups on day 14. The values shown are mean; bars,±SD (n = 4); *P < 0.05 compared with vector control. C. Immunohistochemical staining for the endothelial cell marker CD-31/PECAM-1 was performed on frozen sections prepared from vector-transfected HEK293 cell tumors (top) or TWEAK-overexpressing HEK293 cell line 2 tumors (middle and bottom). Magnification is x10 in the top and middle and x100 in the bottom.