Activation of platelet-activating factor receptor and pleiotropic effects on tyrosine phospho-EGFR/Src/FAK/paxillin in ovarian cancer.
Among the proinflammatory mediators, platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphorylcholine) is a major primary and secondary messenger involved in intracellular and extracellular communication. Evidence suggests that PAF plays a significant role in oncogenic transformation, tumor growth, angiogenesis, and metastasis. However, PAF, with its receptor (PAFR) and their downstream signaling targets, has not been thoroughly studied in cancer. Here, we characterized the PAFR expression pattern in 4 normal human ovarian surface epithelial (HOSE) cell lines, 13 ovarian cancer cell lines, paraffin blocks (n = 84), and tissue microarrays (n = 230) from patients with ovarian cancer. Overexpression of PAFR was found in most nonmucinous types of ovarian cancer but not in HOSE and mucinous cancer cells. Correspondingly, PAF significantly induced cell proliferation and invasion only in PAFR-positive cells (i.e., OVCA429 and OVCA432), but not in PAFR-negative ovarian cells (HOSE and mucinous RMUG-L). The dependency of cell proliferation and invasion on PAFR was further confirmed using PAFR-specific small interfering RNA gene silencing probes, antibodies against PAFR and PAFR antagonist, ginkgolide B. Using quantitative multiplex phospho-antibody array technology, we found that tyrosine phosphorylation of EGFR/Src/FAK/paxillin was coordinately activated by PAF treatment, which was correlated with the activation of phosphatidylinositol 3-kinase and cyclin D1 as markers for cell proliferation, as well as matrix metalloproteinase 2 and 9 for invasion. Specific tyrosine Src inhibitor (PP2) reversibly blocked PAF-activated cancer cell proliferation and invasion. We suggest that PAFR is an essential upstream target of Src and other signal pathways to control the PAF-mediated cancer progression.
Aponte
Margarita
M
Laboratory of Gynecologic Oncology and Epidemiology, Department of Obstetrics and Gynecology and Reproductive Biology, Brigham and Women's Hospital, Dana-Farber Cancer Center, Harvard Medical School, Boston, Massachusetts 02115, USA.
Jiang
Wei
W
Lakkis
Montaha
M
Li
Ming-Jiang
MJ
Edwards
Dale
D
Albitar
Lina
L
Vitonis
Allison
A
Mok
Samuel C
SC
Cramer
Daniel W
DW
Ye
Bin
B
D045744:Cell Line, Tumor; D018450:Disease Progression; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008954:Models, Biological; D009361:Neoplasm Invasiveness; D010051:Ovarian Neoplasms / Q000378:metabolism*; D051419:Paxillin / Q000378:metabolism*; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D015398:Signal Transduction; D014443:Tyrosine / Q000737:chemistry*; D019061:src-Family Kinases / Q000378:metabolism*
D051419:Paxillin; D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; D014443:Tyrosine; D066246:ErbB Receptors; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019061:src-Family Kinases