Isoliquiritigenin(ISL), a calchone flavonoid, has cancer-preventing properties and is often used in Chinese medicine. In the present study, the authors use ISL to determine its effect on cell proliferation and cell cycle progression in primary cultured human uterine leiomyoma cells. Cell viability and cell proliferation assays were conducted. Flow cytometry, annexin V apoptosis assay, and DNA fragmentation assay were performed to determine the effect of ISL on cell cycle and apoptosis. The expression of cell cycle regulatory-related proteins was evaluated by Western blot. The cell viability and proliferation of uterine leiomyoma cells were significantly reduced by ISL treatment in a dose-dependent manner. Flow cytometry results showed that ISL induced subG1 and G2/M arrest. DNA fragmentation assay and annexin V apoptosis assays revealed apoptosis induction. ISL-induced growth inhibition in uterine leiomyoma cells was associated with increased p21(Cip1/) Waf1 expression in a p53-dependent manner. Activation of caspase-3 and downregulation of Bcl-2, cdk 2/4, and E2F, with a concomitant increase in dephosphorylation of Rb and poly-ADP-ribose polymerase cleavage, were observed. This study demonstrates that ISL inhibits cell proliferation by initiating apoptosis in human uterine leiomyoma cells coupled with increased cell cycle arrest. These results indicate that ISL could prove to be a promising chemopreventive and therapeutic agent against human uterine leiomyoma.

Selenophosphate synthetase catalyzes the synthesis of selenophosphate which is a selenium donor for Sec biosynthesis. In Drosophila melanogaster, there are two types of selenophosphate synthetases designated dSPS1 and dSPS2, where dSPS2 is a selenoprotein. The mechanism of gene expression of dSPS2 as well as other selenoproteins in Drosophila has not been elucidated. Herein, we report an essential regulator system that regulates the transcription of the dSPS2 gene (dsps2). Through deletion/substitution mutagenesis, the downstream DNA replication-related element (DRE) located at +71 has been identified as an essential element for dsps2 promoter activity. Furthermore, double-stranded RNA interference (dsRNAi) experiments were performed to ablate transcription factors such as TBP, TRF1, TRF2 and DREF in Schneider cells. The dsRNAi experiments showed that dsps2 promoter activities in DREF- and TRF2-depleted cells were significantly decreased by 90% and 50%, respectively. However, the depletion of TBP or TRF1 did not affect the expression level of dsps2 even though there is a putative TATA box at -20. These results strongly suggest that the DRE/DREF system controls the basal level of transcription of dsps2 by interacting with TRF2.