In human fibrosarcoma cells, antisense suppression of perlecan expression resulted in stimulation of tumor cell growth, both in vitro and in vivo, and increased invasion of ECM. In these cases, lack of perlecan may favor the diffusion of heparinbinding growth factors, leading to enhanced tumor growth.Therefore, the function of perlecan in tumor invasion and metastasis is dependent on the cellular context.Without new blood vessels, tumors cannot expand beyond a few millimeters, the point at which the diffusion of oxygen, nutrients, and the disposal of waste products become limiting. Perlecan may not only affect tumor invasion and metastasis but also support tumor angiogenesis.Perlecan by itself is able to stimulate angiogenesis in a rabbit ear model of in vivo angiogenesis. In human papillary and invasive ductal breast carcinomas, large deposits of perlecan core protein are found in the tumor stroma and blood vessel walls. Similarly, abundant perlecan core protein is detected in the vessel walls and endothelial cells of human Cisapride primary liver tumors. Tumor cells may secrete perlecan to provide a scaffold for blood vessel formation during tumor expansion, and perlecan deposited by tumor cells may further affect tumor growth by binding and modulating the activities of angiogenic growth factors.On the other hand, host cells may synthesize perlecan as a defensive mechanism to limit the diffusion of angiogenic growth factors.Frozen sections of a skin tumor generated by RT tumor cells were stained with rat antimouse perlecan antibody GL. A representative blood vessel is indicated by arrow in each panel.Perlecan deposited around blood vessels was of both tumor and host origin.Downregulation of perlecan in tumor cells inhibits tumor growth and angiogenesis. Perlecandeficient human colon carcinoma cells grow more slowly both in vitro and in vivo compared to the parental cell line.Unlike the parental cell linegenerated tumor xenografts, which reveal extensive invasion of the deep fascia and subcutaneous skeletal muscles with abundant angiogenesis, the perlecandeficient cells generated tumors with sharp boundaries, no infiltration of the deeper soft tissues, and no obvious angiogenesis. Antisense targeting of perlecan in human colon carcinoma and mouse melanoma cells also caused substantial inhibition of tumor growth and angiogenensis. To what Terfenadine extent is the inhibitory effect due to slowed proliferation rather than a lack of angiogenesis?Almost all of these, except integrins, interact with heparin and HS.The VEGF family is composed of six members: VEGFA or VEGF, placenta growth factor. Alternative splicing of the VEGF gene results in five isoforms in human and three isoforms in mice. All VEGF isoforms are covalently linked homodimers.Each monomer contains cysteineknot motif, and two antiparallel monomers are linked together by two intermolecular disulfide bonds formed between C and C. VEGF, a kD glycoprotein, is the predominant isoform.Except for VEGF, all other isoforms bind heparin with high affinity. The expression of the VEGF gene is transcriptionally regulated by hypoxia, which occurs during tumor expansion, and ischemia. In mice, the loss of even a single VEGF allele results in embryonic lethality due to impaired angiogenesis and blood island formation, indicating the irreplaceable function of VEGF in vasculogenesis.In these mice, blood island and blood vessels are absent. due to a failure of endothelial cells to assemble into an organized vascular system.