ABSTRACT
Background:Gemcitabine is the main drug for chemotherapy of advanced pancreatic cancer,however,the prognosis of pancreatic cancer patients has not been changed obviously because of the high innate and acquired resistance of cancer cells to gemcitabine. Aims:To investigate the correlation of DNA repair and expression of human APE1 / Ref-1(apurinic/apyrimidinic endonuclease 1 / redox factor-1),the key enzyme in base excision repair pathway,with the resistance of pancreatic cancer to gemcitabine. Methods:A gemcitabine-resistant human pancreatic cancer cell line SW1990-0. 5 with a resistance index of 9. 32 and its parental cell line SW1990 were treated with gemcitabine. DNA injury was assessed by comet assay. Expressions of APE1 / Ref-1 mRNA and protein were determined by real-time PCR and Western blotting, respectively. Results:In comet assay,after treated with gemcitabine for 24 hours,OTM value of SW1990-0. 5 and SW1990 cells were 0. 32 ± 0. 13 and 26. 96 ± 6. 83,respectively. Expression level of APE1 / Ref-1 mRNA in SW1990-0. 5 cells was 2. 48 ± 0. 49;and expression levels of APE1 / Ref-1 protein in SW1990-0. 5 and SW1990 cells were 1. 57 ± 0. 08 and 0. 84 ± 0. 06,respectively. Statistically significant differences were existed in all these parameters between SW1990-0. 5 and SW1990 cells(P all < 0. 05). Conclusions:DNA repair might be correlated with the resistance of pancreatic cancer to gemcitabine,and up-regulation of APE1 / Ref-1 might contribute to this resistance by its function on DNA repair.
ABSTRACT
Background:Gemcitabine is the first-line drug for chemotherapy of pancreatic cancer. However,owing to the inherent and acquired resistance,gemcitabine does not change obviously the prognosis of patients with pancreatic cancer. Exploration of the mechanism of acquired resistance to gemcitabine is of great clinical importance. Aims:To establish a gemcitabine-resistant human pancreatic cancer cell subclone and to explore preliminarily the resistance mechanism. Methods:Human pancreatic cancer cell line SW1990 was stimulated continuously with 0. 5 μmol/ L gemcitabine in vitro to establish the gemcitabine-resistant subclone SW1990-0. 5. The resistance index of SW1990-0. 5 cells was counted by CCK-8 assay. Proliferation and invasion of SW1990 and SW1990-0. 5 cells were detected by cell doubling time assay and scratch wound healing assay in vitro;cell cycle and cell apoptosis were detected by flow cytometry;expressions of multidrug-resistance related genes(MDR-1,MRP-1,and BRCP)and gemcitabine metabolic enzyme related genes(dCK,RRM1, and RRM2)were determined by real-time PCR. Results:The resistance index of SW1990-0. 5 cells was 9. 32. Compared with the parental SW1990 cells,the proliferation capacity but not the invasion capacity of SW1990-0. 5 cells in vitro was reduced. When treated with gemcitabine,the cell cycle of SW1990-0. 5 cells was similar to that of parental cells,whereas the cell apoptosis was significantly inhibited;expressions of MRP-1,BRCP and dCK mRNA were down-regulated,while expressions of MDR-1,RRM1 and RRM2 mRNA did not change. Conclusions:A stable gemcitabine-resistant human pancreatic cancer cell subclone SW1990-0. 5 was successfully established. Inhibition of cell apoptosis and down-regulation of dCK expression might contribute to the acquired resistance to gemcitabine of pancreatic cancer.