Inhibition of Growth and Metastasis of Ovarian Carcinoma by Administering a Drug Capable of Interfering with Vascular Endothelial Growth Factor Activity

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Abstract
The present study investigates the relationship between in vivo growth/metastasis of tumor cells and their capacity to produce the vascular endothelial growth factor (VEGF), as well as the regulation of tumor growth/metastasis using an angiogenesis‐inhibitory drug. Two cloned tumor cell lines designated OV‐LM and OV‐HM were isolated from a murine ovarian carcinoma OV2944. OV‐LM and OV‐HM cells grew in cultures at comparable rates. However, when transplanted s.c. into syngeneic mice, OV‐HM exhibited a faster growth rate and a much higher incidence of metastasis to lymph nodes and lung. Histologically, intense neovascularization was detected in sections of OV‐HM but not of OV‐LM tumor. OV‐HM and OV‐LM tumor cells obtained from in vitro cultures expressed high and low levels of VEGF mRNA, respectively. A difference in VEGF mRNA expression was much more clearly observed between RNAs prepared from fresh OV‐HM and OV‐LM tumor masses: RNA from OV‐HM contained larger amounts of VEGF mRNA, whereas RNA from OV‐LM exhibited only marginal levels of VEGF mRNA. An angiogenesis‐inhibitory drug, FR118487 inhibited the VEGF‐mediated in vitro growth of endothelial cells but did not affect the expression in vitro of VEGF mRNA by OV‐HM tumor cells. Intraperitoneal injections of FR118487 into mice bearing OV‐HM tumors resulted in: (i) a subsequent growth inhibition of primary tumors; (ii) a marked decrease in neovascularization inside tumor masses expressing comparable levels of VEGF mRNA to those detected in control OV‐HM masses; and (iii) almost complete inhibition of metastasis to lymph nodes and lung. These results indicate that growth/metastasis of tumor cells correlates with their VEGF‐producing capacity and that an angiogenesis inhibitor, FR118487, inhibits tumor growth and metastasis through mechanism(s) including the suppression of VEGF function in vivo.