Moreover, patients with locally advanced HNSCC showed significantly greater downregulation of Per1, Per2 and Per3 mRNA expression levels as compared to patients with early-stage cancer (<i>p</i> < .05).
Perturbation of Per1 expression by MYC constitutes a plausible alternative explanation for the deregulated expression of clock genes observed in many types of cancer.
However, it is still unclear whether the lower expression of PER1 in cancer can influence the expression of other clock genes in the clock gene network.
Analysis of the relations between clinicopathological features and expression of the eight circadian genes in cancer tissue showed that high expression of the Bmal1 gene and low expression of the Per1 gene correlated with liver metastasis.