title: PER1 and CLOCK: potential circulating biomarkers for head and neck squamous cell carcinoma.
abstract: 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.
  
  
  CONCLUSIONS
  CCGs were also altered in PB leukocytes of patients with HNSCC and PER1 and CLOCK are potential circulating prognostic markers for HNSCC.
authors.affiliation: Division of Laryngology, Department of Otolaryngology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan; Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan.
authors.forename: Cheng-Ming
authors.initials: CM
authors.lastname: Hsu
authors.forename: Pai-Mei
authors.initials: PM
authors.lastname: Lin
authors.forename: Chi-Chih
authors.initials: CC
authors.lastname: Lai
authors.forename: Hsin-Ching
authors.initials: HC
authors.lastname: Lin
authors.forename: Sheng-Fung
authors.initials: SF
authors.lastname: Lin
authors.forename: Ming-Yu
authors.initials: MY
authors.lastname: Yang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D056926:CLOCK Proteins / Q000097:blood* / Q000235:genetics; D002294:Carcinoma, Squamous Cell / Q000097:blood*; D016022:Case-Control Studies; D015536:Down-Regulation; D005260:Female; D006258:Head and Neck Neoplasms / Q000097:blood*; D006801:Humans; D007150:Immunohistochemistry; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D056950:Period Circadian Proteins / Q000097:blood* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D012372:ROC Curve; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D014408:Biomarkers, Tumor; C539022:PER1 protein, human; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D056926:CLOCK Proteins; C538943:CLOCK protein, human
keywords: CLOCK; PER1; circadian clock genes; head and neck squamous cell carcinoma; peripheral blood leukocytes