sc-236 and Esophageal-Neoplasms

To investigate the mechanisms responsible for epidermal growth factor (EGF)-induced proliferation of human esophageal squamous cell carcinoma cells.. (3)H-thymidine incorporation assay was used to assess the proliferation of HKESC-1 cells exposed to EGF stimulation. Enzyme immunoassay was used to measure PGE(2) release from HKESC-1 cells, and the protein levels of cyclooxygenase 1 (COX-1), COX-2, EP1 and EP2 in EGF-stimulated cells were determined by Western blotting.. EGF upregulated COX-2 protein expression but produced no obvious effect on COX-1 protein expression in HKESC-1 cells. As a consequence of increased COX-2, EGF further enhanced cellular PGE(2) release. EGF stimulation also resulted in increased protein expression of EP2, a subtype of PGE(2) receptors. Both the non-selective COX inhibitor indomethacin and the selective COX-2 inhibitor SC-236 completely abolished EGF-induced PGE(2) release, and suppressed the mitogenic effect of EGF.. EGF stimulates the proliferation of HKESC-1 cells by increasing COX-2 protein expression and PGE(2) release. Upregulated EP2 protein expression may further amplify the mitogenic action of PGE(2).

Topics: Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Proliferation; Cyclooxygenase 2; Dinoprostone; Epidermal Growth Factor; Esophageal Neoplasms; Humans; Pyrazoles; Receptors, Prostaglandin E, EP2 Subtype; Sulfonamides; Up-Regulation

Doxorubicin is a chemotherapeutic drug widely used for the treatment of advanced esophageal squamous cell carcinoma. However, its efficacy is usually limited by the development of multidrug resistance (MDR), which has been linked to the up-regulation of P-glycoprotein (P-gp) in cancer cells. Conventional nonsteroidal anti-inflammatory drugs and cyclooxygenase 2 (COX-2)-selective inhibitors have been demonstrated to overcome MDR in some cancer cells. Here we sought to elucidate the effect of COX inhibitors on doxorubicin-induced cytotoxicity in relation to P-gp function in human esophageal squamous cell carcinoma cells. Among the five tested COX inhibitors [indomethacin, 4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]-benzenesulfonamide (SC236), 5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluorom-ethylpyrazole (SC560), nimesulide, and N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide (NS398)], all of which substantially suppressed prostaglandin E(2) (PGE(2)) production to a similar extent, only the nonselective COX inhibitor indomethacin and the COX-2-selective inhibitor SC236 enhanced cytotoxic effects of doxorubicin on HKESC-1 and HKESC-2 cells. Moreover, these effects could not be reversed by the addition of PGE(2). Knockdown of COX-2 by small interference RNA also failed to mimic the enhancing effects of indomethacin or SC236, implicating that their action is COX- and PGE(2)-independent. To this end, we observed that indomethacin and SC236 directly functioned as noncompetitive inhibitors of P-gp, which were manifested as a reduction of P-gp ATPase activity. Collectively, these findings suggest that the direct inhibitory effects of indomethacin and SC236 on P-gp may contribute to their ability to increase the intracellular retention of doxorubicin and thus enhance its cytotoxicity. The combination of indomethacin or SC236 with doxorubicin may have significant potential clinical application, especially in the circumvention of P-gp-mediated MDR in cancer cells.

Topics: Adenosine Triphosphatases; Anti-Inflammatory Agents, Non-Steroidal; Antibiotics, Antineoplastic; ATP Binding Cassette Transporter, Subfamily B, Member 1; Carcinoma, Squamous Cell; Cell Line, Tumor; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase Inhibitors; Dinoprostone; Down-Regulation; Doxorubicin; Drug Resistance, Neoplasm; Drug Synergism; Esophageal Neoplasms; Gene Knockdown Techniques; Humans; Indomethacin; NF-kappa B; Pyrazoles; RNA, Small Interfering; Sulfonamides