Biological clock gene PER1 regulates circadian rhythms of BAX, BCL2 and PCNA expression in oral squamous carcinoma cells

Abstract

Objective To explore the regulative role of biological clock gene PER1 in the circadian rhythms of proliferation, apoptosis and expression of intracellular BAX, BCL2 and PCNA in oral squamous carcinoma cells (OSCC). Methods The SCC15 cells stably overexpressing PER1 gene (OE-PER1-SCC15) and negative control SCC15 cells (NC-SCC15) infected with lentiviral virus without PER1 sequence were established. The TSCCA cells with stable PER1 knockdown (RNAi-PER1-TSCCA) and the negative control TSCCA cells (Scramble-TSCCA) of scramble plasmid lentivirus infection without PER1 fragment were also constructed. The cell proliferation index, apoptosis index and the expression of intracellular PER1, BAX, BCL2 and PCNA at 6 different time points within 24 h were detected in each group by flow cytometry, RT-qPCR and Western blotting, respectively. The data were subjected to ANOVA and cosine analysis, and the mesor, amplitude and acrophase were used as indicators to analyze the circadian rhythm characteristics of each gene expression. Results In OE-PER1-SCC15 and NC-SCC15 cells, the cell proliferation index, apoptosis index, and the mRNA and protein levels of PER1, BAX, BCL2 and PCNA showed circadian rhythms (P < 0.05). As compared with the NC-SCC15 cells, the OE-PER1-SCC15 cells had significantly increased mesors of apoptosis index and mRNA and protein levels of PER1 and BAX, while decreased mesors of proliferation index and mRNA and protein levels of BCL2 and PCNA (P < 0.05). The amplitudes of apoptosis index and BAX mRNA level were remarkably elevated, while those of BCL2 and PCNA mRNA levels were reduced in OE-PER1-SCC15 cells (P < 0.05). In addition, the acrophases of apoptosis index, and PER1 and BAX mRNA and protein levels were notably advanced, which were delayed in proliferation index, mRNA and protein levels of BCL2 and PCNA. When compared with the Scramble-TSCCA cells, the circadian rhythm of BAX protein expression was disturbed in the RNAi-PER1-TSCCA cells, but the cell proliferation index, apoptosis index and the mRNA and protein levels of PER1, BCL2 and PCNA, as well as mRNA level of BAX presented circadian rhythms (P < 0.05), whose characteristics were opposite to those of OE-PER1-SCC15 cells. Conclusion The changes in PER1 expression lead to the alteration in both its own circadian rhythm characteristics, and the circadian rhythm characteristics of proliferation, apoptosis, and BAX, BCL2, and PCNA expression in OSCC cells.

Keywords

• per1
• circadian rhythm
• oral squamous cell carcinoma cell proliferation
• cell apoptosis