Phosphatidylinositol 3-kinase mediates angiogenesis and vascular permeability associated with ovarian carcinoma.
OBJECTIVE
To assess the role of phosphatidylinositol-3 kinase (PI3K) inhibition in vascular permeability, angiogenesis, and vascular remodeling in tumor vessels and peritoneal lining in an athymic mouse model of i.p. human ovarian carcinoma.


METHODS
Mice were inoculated i.p. with cells from the human ovarian cancer cell line, OVCAR-3. Fourteen days after inoculation, mice were treated with or without the PI3K inhibitor LY294002, 3 days weekly for 4 weeks. At the end of the experiment, some mice were anesthetized and injected via the tail vein with FITC-labeled lycopersicon lectin and perfused through the aorta before sacrifice. The peritoneal wall and tumor from all mice were removed and embedded in 10% agarose. Tumor sections were visualized by fluorescence microscopy.


RESULTS
Ascites in the LY294002-treated group (0.69 +/- 0.27 mL) was reduced by 72.4% compared with the control group (2.5 +/- 1.2 mL). Tumor burden in the LY294002-treated group (0.62 +/- 0.32 g) was reduced by 47.3% compared with the control group (1.18 +/- 0.41 g). LY294002 inhibited peritoneal and tumor vascularization resulting in numerous leaky, irregular, tortuous vessels in scant, straight, relatively impermeable vessels.


CONCLUSIONS
The data indicate that LY294002 inhibits ascites formation in our mouse model of human ovarian cancer by inhibiting tumor and peritoneal neovascularization as well as vascular permeability. The data also show that LY294002 directly inhibits vascular endothelial growth factor (VEGF) protein expression and release from ovarian carcinoma and suggest that LY294002 blocks the VEGF signaling pathway involved in angiogenesis and vascular permeability.
Hu
Limin
L
Center for Reproductive Sciences, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, CA 94103-05556, USA. jaffer@obgyn.ucsf.edu
Hofmann
Judith
J
Jaffe
Robert B
RB
D000818:Animals; D001201:Ascites / Q000378:metabolism; D002199:Capillary Permeability; D045744:Cell Line, Tumor; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008819:Mice, Nude; D008856:Microscopy, Fluorescence; D009025:Morpholines / Q000494:pharmacology; D009389:Neovascularization, Pathologic; D010051:Ovarian Neoplasms / Q000098:blood supply* / Q000473:pathology / Q000517:prevention & control; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis; D023041:Xenograft Model Antitumor Assays / Q000379:methods
D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D042461:Vascular Endothelial Growth Factor A; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one