Fig. 6: TRF2 overexpression rescued ActD and serum starvation-induced HCC cell-cycle arrest.

a MMC7721 cells were transfected with TRF2 for 48 h, the cells were then treated with ActD for 10 h, and subjected to flow cytometry cell-cycle analysis. S- and G2-phase arrest was induced following ActD treatment, and the overexpression of TRF2 could partly rescue the cell-cycle arrest. The histogram is the statistics cell cycle. b SMMC7721 cells were transfected with TRF2 for 48 h and were treated with DMEM (0.1% FBS) for 24 h and flow cytometry cell-cycle analysis was performed. c, d HepG2 cells were used for cell-cycle analysis and was performed as described in a and b. The histogram is the statistics of the cell cycle. All values are presented as mean ± SD of at least three independent experiments; **p < 0.01. e A proposed working model to explain how NOLC1 functions in the nucleolar accumulation of TRF2 and the effects of TRF2 on rRNA synthesis and cell-cycle regulation. Under normal conditions, the levels of TRF2 in the nucleolus and at telomeres are strictly balanced. When NOLC1 expression increases, TRF2 accumulates in the nucleolus and promotes rRNA synthesis, which promotes cell-cycle progression