title: Reversal effect of ouabain on multidrug resistance in esophageal carcinoma EC109/CDDP cells by inhibiting the translocation of Wnt/β-catenin into the nucleus.
abstract: The incidence of esophageal carcinoma is increasing throughout the world. A major obstacle to its treatment is acquired multidrug resistance (MDR) which results in the failure of chemotherapy and patient relapse. Here, we identified that ouabain is capable of reversing MDR to cisplatin (CDDP) in EC109/CDDP cells and explore the possible mechanisms of action. The parental and the MDR cell lines were both sensitive to ouabain with 50 % inhibitory concentration (IC50) values of 258.11 and 710.63 nM, respectively. Cisplatin cytotoxicity increased in the EC109/CDDP cells by the addition of ouabain which helps promote CDDP-induced apoptosis. Ouabain at 20 nM effectively reduced the IC50of CDDP in EC109/CDDP cells from 36.54 to 3.39 μM. This represents a 10.78-fold increase in sensitization to CDDP. We also found that ouabain was capable of down regulating the expression of P-glycoprotein (P-gp) and Bcl-2 in a dose- and time-dependent manner. Finally, the results indicated that ouabain suppressed Wnt luciferase report (TOPFlash) activity obviously in EC109/CDDP and depressed the translocation of β-catenin into the nucleus. Moreover, ouabain showed reversal effect of MDR to CDDP in nude mouse xenograft model, and reduced the protein level of β-catenin (Y333) in tumor tissue of CDDP plus ouabain group. All data proved that ouabain has a potent β-catenin-dependent anti-MDR effect.
authors.affiliation: Department of Radiotherapy and Oncology, The Second Affiliated Hospital of Soochow University, San Xiang Road No. 1055, Suzhou, Jiangsu, 215004, China.|Institute of Radiotherapy and Oncology, Soochow University, San Xiang Road No. 1055, Suzhou, Jiangsu, 215004, China.|Suzhou Key Laboratory for Radiation Oncology, San Xiang Road No. 1055, Suzhou, Jiangsu, 215004, China.|Department of Oncology, Affiliated Haian Hospital of Nantong University, Zhongba Middle Road, No. 17, Haian Town, Haian County, Nantong, Jiangsu, 226601, China.
authors.forename: Yucheng
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Laboratory Animal Center of Nantong University, Qi Xiu Road No.19, Nantong, Jiangsu, 210061, China.
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Radiotherapy and Oncology, The Second Affiliated Hospital of Soochow University, San Xiang Road No. 1055, Suzhou, Jiangsu, 215004, China. proftianye@126.com.|Institute of Radiotherapy and Oncology, Soochow University, San Xiang Road No. 1055, Suzhou, Jiangsu, 215004, China. proftianye@126.com.|Suzhou Key Laboratory for Radiation Oncology, San Xiang Road No. 1055, Suzhou, Jiangsu, 215004, China. proftianye@126.com.
authors.forename: Ye
authors.initials: Y
authors.lastname: Tian
keywords: Esophageal carcinoma; Multidrug resistance; Ouabain; Wnt/β-catenin