Triptorelin Reverses Cisplatin Resistance In Human Ovarian Carcinoma Cell Line (OVCAR-3) Via EGFR Signal Pathway

Introduction At present,chemotherapy is one of the primary modalities for the treatment of ovarian carcinoma.The cisplatin is one of the most effective anticancer drugs.However, the acquired resistance to cisplatin is one of the most significant reasons for relapsing and recurrence of the ovarian cancer.Various studies demonstrated that the epidermal growth factor receptor-mediated signal transduction in human ovarian cancers plays an important role in celluar reproduction and development of acquired resistance to drugs.About 70%-100%of ovarian cells overexpress receptors for EGF.The ovarian cells with expression of EGFR have more ability of metastasis,invasion,insensitivity to chemotherapy or radiotherapy,poor prognosis,high recurrence rate and short life span.Other studies have shown that antiproliferative effet of GnRH and its analogs(GnRHa) in ovarian cancer cells may probably mediated by down-regulation expression of EGFR.The antiproliferative effects of GnRHa and the resistance to cisplatin in ovarian cancer cells are both mediated by the EGFR signal pathway,so we presume that GnRHa(Triptorelin) canreverse acquired resistance to cisplatin.The purpose of our study is to explore the potentiation effect of Triptorelin for chemotherapy.Objective To show down-regulation of expression of EGFR of Triptorelin contributes to reversion effects in OVCAR-3/DDP cells,which are resistant to cisplatin.MethodsPartâ… Generation and maintenance of resistant subclone:1,The cisplatin-resistant subclone(OVCAR-3/DDP) was established by maintaining the cells with stepwise increases in the concentration of cisplatin;2,The changes of cellular morphology were observed by phase-contrast microscope;3,IC₅₀(50%inhibiting concentration) and RI(resistance index) were detected by MTT assay;4,The cell cycle and the cell apoptosis were detected by flow cytometry.Partâ…¡Explore the potentiation effect of triptorelin forchemotherapy:1,Experiment groups:we divided five groups asâ… cisplatin,â…¡Triptorelin,â…¢combination(cisplatin and Triptorelin),â…£non-drug,â…¤parental cells all based on concentrations of C_max of both drugs.â… -â…£groups use OVCAR-3/DDP cells andâ…¤group uses OVCAR-3 cells.2, The doubling time(Td),RI and RR were detected by MTT assay;3,After treated with cisplatin,Triptorelin,and combination of cisplatin and Triptorelin in different concentration respectively,the proliferation and EGFR expression of cells of every group were detected by MTT assay and flow cytometry.ResultsPartâ… Establishment of OVCAR-3/DDP 1,The resistant cell lines were named OVCAR-3/DDP.Even when OVCAR-3/DDP cells were grown in the absence of cisplatin for further 2 months,their resistant properties were sustained;2,Cellular morphology. compared with parental cells,OVCAR-3/DDP cells were larger in volume and intercellular space;3,OVCAR-3/DDP cells were 13.42-fold more resistant to cisplatin than the parent cisplatin sensitive OVCAR-3 cells;IC₅₀ values were 6.22 and 83.48μM for OVCAR-3 and OVCAR-3/DDP cells,respectively;4,A clear G₀/G₁ phase block in OVCAR-3/DDP cells was shown.Partâ…¡1,Direct antiproliferative effects of Triptorelin:the reversal reaction(RR) induced by the combination was 3.91;2,Effects of Triptorelin on EGFR: overexpression of EGFR is in both OVCAR-3/DDP and OVCAR-3 cells.Fluorescence intensity of EGFR of OVCAR-3/DDP cells was down-regulated obviously by the combination(cisplatin and Triptorelin).Conlusions:1,Cisplatin-resistant cell subline OVCAR-3/DDP was an essentially experimental model in vitro for the study on reversion effects of cisplatin resistance;2,Triptorelin probably resensitizes resistant ovarian cancer cells to cisplatin in vitro by modulating the expression of EGFR.