Up-regulation of P-glycoprotein is involved in the increased paclitaxel resistance in human esophageal cancer radioresistant cells

Abstract Objective. Development of drug and radiation resistance is one of the major causes of cancer treatment failure with chemoradiotherapy. Whether radiotherapy affects drugs resistance in esophageal cancer cells remain to be determined. The purpose of the study was to investigate the change of drug-sensitivity and P-glycoprotein (P-gp) expression in ionization radiation-induced human esophageal cancer radioresistant cells. Materials and methods. Radioresistant cells were established by means of continuous fractionated gamma-ray irradiation on human esophageal squamous cancer cell line EC9706. The radiosensitivity and drug-sensitivity between established radioresistant cells and parental cells were detected by a colony-forming assay and 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay, respectively. The expressions of multidrug resistance type 1 gene (MDR1) mRNA and protein for P-gp were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot met...