Forced COX-2 expression induces PGE2 and invasion in immortalized urothelial cells

Objectives: Cyclooxygenase 2 (COX-2) is aberrantly expressed in multiple tumor types including bladder cancer is associated with enhanced growth, resistance to apoptosis, invasion, and angiogenesis. To evaluate the mechanisms through which COX-2 expression alters normal urothelium, we transfected the SV-40 immortalized human urothelial cell line SV-HUC with COX-2. Methods: SV-HUC cells were stably transfected with a plasmid containing COX-2 Under a CMV promoter. Following isolation (of monoclonal transfectants, COX-2 expression was determined by Western and Northern analyses. Prostaglandin E-2 (PGE(2)) in the culture supernatant was measured by ELISA. Cell growth was measured by crystal violet assay. Cellular invasion through Matrigel and anchorage-independent growth in 0.4% agarose were assessed. Tumorigenicity was evaluated by subcutaneous injection of cells in nude mice with and without Matrigel. Results: Four of 12 clones stably overexpressing COX-2 at high levels relative to vector-transfected control cells were chosen for further study. Cell growth rates of these 4 clones were higher than vector control cells. PGE(2) production was elevated in 3 of these 4 clones, and PGE(2) levels correlated significantly with invasion through Matrigel. COX-2-transfected cells did not form colonies in soft agarose or tumors in nude mice. Conclusions: Forced COX-2 expression in SV-HUC immortalized urothelial cells contributes to increased PGE(2) production and increased invasion through Matrigel. However, it is insufficient to induce malignant transformation. (c) 2008 Elsevier Inc. All rights reserved.