Effect of clock gene PER1 knockdown on clock gene networks in human oral squamous cell carcinoma

Abstract

This study investigated the effect of clock gene PER1 on the expression levels of other clock genes in clock gene networks in oral squamous cell carcinoma cells. We used RNA interference mediated by short hairpin RNAs (shRNAs) to effectively knock down PER1 in SCC15 human oral squamous cell carcinoma cells. Flow cytometry was used to detect the degree of proliferation and apoptosis of the cells after PER1 knockdown, and quantitative real-time PCR was used to detect the mRNA expression levels of the clock genes CLOCK, BMAL1, PER1, PER2, PER3, DEC1, DEC2, CRY1, CRY2, TIM, CKIE, RORA, NPAS2, and REV-ERBA. The proliferation index of SCC15 cells increased significantly while the apoptotic index decreased significantly after PER1 knockdown (P<0.05). The mRNA expression levels of PER1, PER2, DEC1, DEC2, CRY1, CRY2, and NPAS2 markedly decreased (P<0.05) while those of PER3, TIM, RORA, and REV-ERBA markedly increased (P<0.05). By contrast, no obvious changes were observed in the mRNA expression levels of CLOCK, BMAL1, and CKIE (P>0.05). The clock gene PER1 can regulate the expression levels of other clock genes in the clock gene networks; these genes include PER2, DEC1, DEC2, CRY1, CRY2, NPAS2, PER3, TIM, RORA, and REV-ERBA. PER1 gene thus plays an important role in the regulation of clock gene networks. .