Abstract: Objective This study aims to explore the molecular mechanism by which YAF2 up-regulates cyclin D1 expression in tumor cells as well as the effect of YAF2-cyclin D1 regulatory loop on tumor cell proliferation. Methods Overexpression and knockdown experiments combined with Western blot and real-time quantitative PCR were used to detect the expressions of YAF2 and cyclin D1; Dual luciferase reporter assay was performed to investigate the effect of YAF2 on cyclin D1 promoter activity; Flow cytometry analysis was carried out to elucidate the effect of YAF2 on cell cycle progression through targeting cyclin D1; Colony formation assay was employed to determine cell proliferation under different YAF2 and cyclin D1 expression levels. Results YAF2 upregulates the expression of cyclin D1 at both the mRNA (P<0.05) and protein levels; YAF2 activates the promoter activity of cyclin D1 (P<0.05); YAF2 silencing increases the proportion of cells in G0/G1 phase (P<0.0001) and reduces the proportion of cells in S phase by regulating cyclin D1 (P<0.002); YAF2 facilitates the cell colony formation via targeting cyclin D1 (P<0.05). Conclusions In tumor cells, YAF2 promotes the expression of cyclin D1, and enhances cell cycle progression and cell proliferation.

Key words: Keyword: YAF2, Cyclin D1, Tumor cell proliferation