RÉSUMÉ
Objective To study the effect of Numb gene on cell cycle and proliferation in human renal carcinoma cells and its related mechanism. Methods Renal carcinoma cells Caki-1 were taken as research objects, and the Numb-ORF plasmid transfected cells, negative control group and blank control group were set respectively. The expression levels of Numb and cyclin D1 were detected by real-time PCR and Western blot. The cell cycle was analyzed respectively by flow cytometry. Cell proliferation was assessed by comparing with absorbance at 490 nm using a micro-plate reader. Results Compared to the negative control group (5.05±0.45) and blank control group (5.13±0.31), the △Ct value of Numb in the Numb-ORF group (1.92±0.39) was significantly lower. The protein levels in the Numb-ORF group, the negative control group and the blank control group were 6.67±0.83, 3.08±0.47, 2.85±0.36, respectively (P = 0.00). Meanwhile, the △Ct value of cyclin D1 in the Numb-ORF group (6.20±0.87) was higher than that in the negative control group (4.35±0.51) and the blank control group (4.56±0.31) (P = 0.02), and the protein level in the Numb-ORF group (5.85±0.72) was lower than that in the negative control group (10.04±0.83) and the blank control group (11.88±1.26) (P = 0.00). The ratio of G0/G1 cells in the Numb-ORF group was (54.29±4.15) %, the negative control group was (38.69±2.60) % and the blank control group was (41.28±1.29) % (P = 0.00). In proliferation assay, compared with the negative control group (0.93±0.10) and the blank control group (1.02±0.06), the A value at 24 h in the Numb-ORF group (0.67±0.07) was significantly reduced (P = 0.00). Conclusion Numb gene could increase the cell percentage in G0/G1 phase and inhibit proliferation of renal carcinoma cells via down-regulating the expression of cyclin D1.