PER1 and CLOCK: Potential circulating biomarkers for head and neck squamous cell carcinoma

Background Circadian clock regulates daily rhythms in various physiologic processes and deregulated circadian clock are linked to cancers. We have previously demonstrated the association between altered circadian clock genes (CCGs) and head and neck squamous cell carcinoma (HNSCC). The purpose of this study was to investigate whether the CCGs were also altered in peripheral blood (PB) of patients with HNSCC. Methods The 9 CCGs expression profiles of PB leukocytes from 94 patients with HNSCC and 56 healthy individuals were investigated using real‐time quantitative reverse transcriptase‐polymerase chain reaction (qRT‐PCR) and immunocytochemistry. Results All the 9 CCGs were significantly downregulated in the PB of preoperative patients (p < .0001). Recovery of PER1 and CLOCK expression was observed in postoperative patients with good prognosis but not in patients that died within 1 year after surgery. Conclusion CCGs were also altered in PB leukocytes of patients with HNSCC and PER1 and CLOCK are potential circulating prognostic markers for HNSCC. © 2013 Wiley Periodicals, Inc. Head Neck 36: 1018–1026, 2014