In vitro and in vivo inhibitory effect of three Cox-2 inhibitors and epithelial-to-mesenchymal transition in human bladder cancer cell lines.

BACKGROUND: Although the anti-tumour effect of cyclooxygenase-2 (Cox-2) inhibitors in invasive bladder cancer has been confirmed, its mechanisms of action are unclear. Recently, the concept of an epithelial-to-mesenchymal transition (EMT) promoting carcinoma progression has been suggested, and a key feature of the EMT is the downregulation of E-cadherin. In this study, we investigated the effect of Cox-2 inhibitors on reversal EMT and tumour growth inhibition in bladder cancer cells. METHODS: We used three Cox-2 inhibitors, etodolac, celecoxib and NS-398 and three human bladder cancer cell lines, T24, 5637 and KK47, in this study. T24 xenograft tumour mouse model was used in the in vivo study. RESULTS: Within the clinical drug concentrations, only etodolac showed the in vitro growth inhibition in T24 not in the other cell lines. Etodolac reduced SNAIL mRNA and vimentin cell surface expression, and induced E-cadherin mRNA and E-cadherin cell surface expression, in T24. Etodolac also most strongly inhibited the cell migration of T24 in vitro and showed the highest tumour growth inhibition in T24 tumour in vivo. CONCLUSION: Etodolac at clinical doses exhibited induced in vitro and in vivo anti-tumour effects and reversal effect of EMT in T24. These results suggest that etodolac is a good candidate for an anti-tumour or chemopreventive reagent for high-grade bladder cancer.

E10A, an adenovirus-carrying endostatin gene, dramatically increased the tumor drug concentration of metronomic chemotherapy with low-dose cisplatin in a xenograft mouse model for head and neck squamous-cell carcinoma.

Most cancer chemotherapeutic agents are administered at the maximum-tolerated dose (MTD) in short cycles with treatment breaks. However, MTD-based chemotherapies are often associated with significant toxicity and treatment breaks allow the opportunity for tumor regrowth and acquisition of chemoresistance. To minimize these drawbacks, a metronomic strategy, in which chemotherapeutics are administered at doses significantly below the MTD without treatment breaks, has been suggested by many investigators. The antitumor effect of metronomic chemotherapy may be partially due to inhibition of tumor angiogenesis, and it could be enhanced by a combination therapy, including antiangiogenic agents. In this study, we evaluated the synergistic effect of E10A, an adenovirus carrying the endostatin gene, the most potent inhibitors of tumor angiogenesis, in combination with weekly low-dose cisplatin in a xenograft mouse model for head and neck squamous-cell carcinoma. The E10A induced mRNA and protein expressions of endostatin in H891 cells in vitro. E10A significantly enhanced the in vivo tumor growth inhibitory effect of cisplatin. Immunohistochemical analysis with a TUNEL (terminal deoxynucleotidyl transferase-mediated nick-end labeling) assay and anti-CD31 antibodies revealed that the combination of E10A and cisplatin induced high levels of cell apoptosis and inhibited tumor angiogenesis. Importantly, E10A increased the platinum concentrations in tumors to fivefold higher than that induced by cisplatin alone.