The Multidrug Resistance Characteristic Induced By Taxol In Hypopharyngeal Carcinoma FaDu And The Mechanism

Hypopharyngeal carcinoma is one of the most highly malignant tumor in head and neck squamous cell carcinoma, Due to the hidden location, most patients have been found in advanced, the5year survival rate was only30%-50%. The tradition surgical methods can not preserve the larynx organ, leading to the survival quality of the patients decreased. The chemotherapy with the purpose of organ retention does not improve survival rate, The5year survival rate remain40％～60％. In recent years, people advocate operation combined with radiotherapy and chemotherapy to improve patient survival rate and life quality. The commonly used chemotherapy drugs in clinical including cisplatin (DDP),5-fluorouracil (5-FU), doxorubicin (Dox), and vincristine (VCR). With the application of these chemotherapy agents, the drug resistance produced by the tumor cells thereby reducing the treatment effect. As a new generation drugs of chemotherapy, taxol has been widely used in advanced or recurrent hypopharyngeal carcinoma and achieved the prominent effect. Studies show that the clinical trial efficacy than other traditional chemotherapy drugs. Even so, the drug resistance of tumor cells to Taxol remains the biggest obstacle for chemotherapy. To further investigate the mechanism of drug resistance in hypopharyngeal cancer, a multidrug resistant cell line to Taxol (FaDu/T) was established by exposing normal hypopharyngeal carcinoma FaDu cells to escalating concentration of Taxol in stepwise. The various expression of MDR relative protein ABCB1, ABCG2in FaDu and FaDu/T was compaired investigated. Meanwhile we detected the effect of JNK signal transduction pathways in the expression of ABCB1, ABCG2to further reveal the mechanism of MDR and the regulation of ABCB1, ABCG2in hypopharyngeal cancer. These findings may provide theoretical support for the reverse of MDR in clinical Objective In this study, we aimed to detect the increased MDR characteristic of FaDu/T than FaDu and then investigate the expression of MDR relative protein ABCB1and ABCG2to reveal the reason of MDR in FaDu/T cell lines. Meanwhile we investigated the function of JNK Signal transduction pathways in the regulation of the various expression of ABCB1, ABCG2in these two kinds of cell lines, and all these can prove theory support for the reverse of hypopharyngeal cancer.Methods Human FaDu cells were exposed in stepwise escalating concentration of Taxol until the resistant cell line FaDu/T was formed. The multidrug resistance sensitivities of FaDu and FaDu/T to5-FU, DDP, DOX, VCR were investigated by Methyl-Thiazolyl-Tetrazolium (MTT) assay; Reverse Transcription Polymerase Chain ReActin (RT-PCR), Western blot and Laser confocal microscope were conducted to detect mRNA and protein levels of the multidrug resistance genes ABCB1, ABCG2. The relative proteins levels of JNK Signal transduction pathways were detect through Western blot.Results1. The drug resistance cell line of FaDu/T was build up succeed which can growth normally in the medium containing Taxol.2. The mutidrug resistance of FaDu/T cells toDDP,5-FU, DOX and VCR were all increased than FaDu cells.3. Compared with FaDu cells, the multidrug resistance gene ABCB1was increased significantly at gene and protein levels in FaDu/T cells but the expression of ABCG2was reversely.4. The JNK Signal transduction pathways was inactivation in FaDu or FaDu/T cell lines and which can be reactivated by Taxol and the activator of MAPK signal transduction pathways Anisomycin respectively。5. When the Anisomycin was induced in FaDu/T cells, the expression of ABCB1was up-regulated, the ABCG2changed reversely. But they would be no prominate variation if FaDu/T cells were pretreatment with the JNK inhibitor SP600125, thus the JNK Signal transduction pathways play an important role in the regulation of ABCB1and ABCG2.Conclusions The overexpression of ABCB1is the critical reason of MDR in FaDu/T cell lines. JNK signal transduction pathways could regulate the various expression of ABCB1and ABCG2in FaDu/T cell line. Different MDR relative protein alternate expression in different kinds of tumor cells maybe the main reason of the chemotherapy failure.