title: Caveolin-1 regulates VEGF-stimulated angiogenic activities in prostate cancer and endothelial cells.
abstract: Caveolin-1 (cav-1) is a multifunctional protein and major component of caveolae membranes serving important functions related to signal transduction, endocytosis, transcytosis, and molecular transport. We previously showed that cav-1 is overexpressed and secreted by metastatic prostate cancer cells. We now report that cav-1 gene transduction (Adcav-1) or recombinant cav-1 (rcav-1) protein treatment of cav-1-negative prostate cancer cell line LP-LNCaP or cav-1(-/-) endothelial cells potentiated VEGF-stimulated angiogenic signaling. Downregulation of cav-1 in prostate cancer cell line PC-3 or human umbilical vein endothelial cells (HUVECs) through cav-1 siRNA significantly reduced basal and VEGF-stimulated phosphorylation of VEGFR2 (Y951), PLCgamma1 (Y783) and/or Akt (S473 & T308) relative to those in control siRNA treated cells. Additionally rcav-1 stimulation of cav-1 siRNA treated HUVECs restored this signaling pathway. Confocal microscopy and immunoprecipitation analysis revealed association and colocalization of VEGFR2 and PLCgamma1 with cav-1 following VEGF stimulation in HUVECs. Interestingly, treatment of HUVECs with cav-1 scaffolding domain (CSD) caused significant reduction in the VEGF-stimulated phosphorylation of VEGFR2, PLCgamma1 and Akt suggesting that CSD inhibits cav-1-mediated angiogenic signaling. VEGF stimulation of HUVECs significantly increased tubule length and cell migration, but this stimulatory effect was significantly reduced by cav-1 siRNA and/or CSD treatment. The present study demonstrates that cav-1 regulates VEGF-stimulated VEGFR2 autophosphorylation and activation of downstream angiogenic signaling, possibly through compartmentalization of specific signaling molecules. Our results provide mechanistic insight into the role of cav-1 in prostate cancer and suggest the use of CSD as a therapeutic tool to suppress angiogenic signaling in prostate cancer.
authors.affiliation: Department of Genitourinary Medical Oncology Research, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA.
authors.forename: Salahaldin A
authors.initials: SA
authors.lastname: Tahir
authors.forename: Sanghee
authors.initials: S
authors.lastname: Park
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Thompson
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism; D015153:Blotting, Western; D051242:Caveolin 1 / Q000037:antagonists & inhibitors / Q000502:physiology*; D002448:Cell Adhesion; D002465:Cell Movement; D049109:Cell Proliferation; D004730:Endothelium, Vascular / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic; D051966:Phospholipase C gamma / Q000378:metabolism; D010766:Phosphorylation; D011471:Prostatic Neoplasms / Q000098:blood supply* / Q000235:genetics / Q000473:pathology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D015398:Signal Transduction; D014471:Umbilical Veins / Q000166:cytology / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D014945:Wound Healing
chemical_list: D051242:Caveolin 1; D034741:RNA, Small Interfering; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2; D051057:Proto-Oncogene Proteins c-akt; D051966:Phospholipase C gamma