Abstract Objective The aim of this study was to investigate the effect of cinobufotalin on apoptosis in renal cell carcinoma and its possible mechanism of action. Methods The expression levels of Notch1 in renal cancer cells, as well as in adjacent and normal tissues were assessed in 64 patients with renal cellcarcinoma. The 769-P cells were treated with 0, 10, 20 and 40 mg/L cinobufotalin and the proliferation activity and apoptotic rate of the cells were measured. The expression levels of Notch1, Bcl-2, and Pro-caspase 3 were detected by RT-PCR and Western-blot. Results (1) The rates of Notch1 expression in renal cancer cells, adjacent tissues, and normal tissues were 75.0%, 45.3%, and 9.4%, respectively. Notch1 expression had significant effects on tumor, node and metastasis (TNM) staging, Fuhrman grade, and tumor size in patients with renal cell carcinoma (P < 0.05); (2) The inhibition rates of cinobufotalin on 769-P cells were 0%, 6.85%, 11.37%, and 16.33% at 24 h; 0%, 13.57%, 20.14%, and 31.69% at 48 h; 0%, 19.97%, 28.53% and 51.42% at 72 h. At 24 h, the apoptotic rates were 8.2 ± 3.1%, 19.8 ± 5.6%, 33.7 ± 5.0%, and 51.5 ± 6.8%.The effect of cinobufotalin on apoptosis of 769-P cells was dose-dependent; (3) RT-PCR assay showed that protein expression levels for Notch1, Bcl-2, and Pro-caspase 3 were significantly decreased with the increase of drug concentration. Western-blot analysis also showed that Notch1, Bcl-2 and Pro-caspase 3 protein levels showed a significant downward trend with the increase of drug concentration. Conclusion Cinobufotalin inhibits the growth of renal cancer cells and induces apoptosis in renal cell carcinoma, which may be related to the inhibition of Notch1 signal activation.
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