| Summary: | 碩士 === 高雄醫學大學 === 生物化學研究所碩士班 === 95 === Cisplatin is one of the most effective anticancer drugs used for treatment of solid tumors, including ovarian, small cell lung and bladder cancers. During the cisplatin treatment of urothelial cancer, some patients will become to be cisplatin resistance, and then it will influence the outcome of treatment. Therefore, it is an important topic how to characterize the cisplatin-resistant mechanism in human urothelial carcinoma (UC) cells. In this study, we discovered that CEBPD (CCAAT/enhancer binding protein delta), a member of the transcription regulator protein, C/EBP, was higher expressed in cisplatin-resistant cells than in As2O3, paclitaxel and gemcitabine-resistant cells. Then we established the CEBPD transfectant subclones, N-vector and N-CEBPD by stable transfection. In MTT assay,
the IC50 value of N-CEBPD in response to cisplatin was 2.9-fold than NTUB1 (P<0.001). It indicated two cell lines were significant different in cisplatin resistance. Our results showed the lower P53 protein level in N-CEBPD than N-vector when cells were treated with 10 μM 24hr, and P53-p-ser15, p-ERK were inactivated. The expression of these proteins
were similar with NTUB1/P(14) in basal level or in cisplatin-treatment. We also found higher protein level of superoxide dismutase (SOD) in N-CEBPD than in N-vector and N-CEBPD-ΔDBD. Based on the DAPI staining and flowcytometry assays, N-CEBPD had less DNA fragmentation and sub-G1
fraction than in control cells when cells were treated with 20 μM 24hr. Therfore, in overexpressed CEBPD cells, they can increase cisplatin resistance through deactivated p-ERK and P53-p-ser15 when cells are treated with cisplatin. We also find that the transcriptional activity of CEBPD is very important in cisplatin-resistance. Briefly, cisplatin-resistant mechanism is associated with the CEBPD expression in UC.
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