COX-2 overexpression increases motility and invasion of breast cancer cells.
Cyclooxygenase-2 (COX-2), an inducible enzyme involved in prostaglandin (including PGE(2)) biosynthesis, is overexpressed in several epithelial malignancies including breast cancer. We tested the hypothesis that COX-2 overexpression in breast cancer cells results in increased cell motility and invasion. COX-2 overproducing cells were generated by stable transfection of several human breast cancer cells with pSG5-COX2 vector. We confirmed the overexpression of COX-2 protein by western blotting, and by measuring PGE(2) in the medium with an immunoassay. We measured cell motility by counting the number of cells crossing an 8-micron pore size PET membrane, and cell invasion by counting the number of cells invading through a Matrigel-coated membrane that simulates basement membrane. COX-2 transfected MDA-231 cells produced 30-43-fold more PGE2 as compared to parental cells. COX-2 overexpression increased cell migration approximately 2.2-fold and cell invasion through Matrigel approximately 5.1-fold. Addition of 50 microM NS-398, a COX-2 inhibitor, inhibited Matrigel invasion of MDA-231 cells by 54% as compared to solvent confirming the role of COX-2 in cell invasion. It is known that an increase in cell migration and invasion can be brought about by cytoskeletal alterations and basement membrane degradation due to increased expression of pro-urokinase plasminogen activator (pro-uPA). To investigate the mechanism of our observed increase in cell invasion by COX-2, we found by western blotting that the level of pro-uPA was significantly higher (approximately 5-fold) in COX-2 transfected MDA-231 cells than untransfected MDA-231 cells. Similar to our observations in cell culture, we found evidence that increased COX-2 activity correlates with uPA in a mouse model of breast cancer metastasis to bone. In this study, we conclude that COX-2 overexpression in human breast cancer cells enhances cell motility and invasiveness thus suggesting a mechanism of COX-2 mediated metastasis.
Singh
Balraj
B
Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA.
Berry
Jacob A
JA
Shoher
Angela
A
Ramakrishnan
Vijay
V
Lucci
Anthony
A
D000818:Animals; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology*; D002465:Cell Movement; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000096:biosynthesis; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D007118:Immunoassay; D008565:Membrane Proteins; D051379:Mice; D009361:Neoplasm Invasiveness; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured
D008565:Membrane Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone