title: Abnormal expression of PER1 circadian-clock gene in oral squamous cell carcinoma.
abstract: BACKGROUND
  The PER1 circadian-clock gene plays an important role in the regulation of many normal physiological rhythms in vivo. It has been revealed recently that abnormal expression of PER1 correlates closely with the occurrence and development of many cancers. However, the expression and significance of PER1 in oral squamous cell carcinoma (OSCC) remains unknown. The purpose of the present study was to investigate the direct links between aberrant PER1 expression and clinicopathological features of OSCC.
  
  
  METHODS
  PER1 expression in cancerous and adjacent noncancerous tissues from 41 patients with OSCC was detected by immunohistochemical staining and real-time reverse transcriptase polymerase chain reaction, and correlations were sought with clinicopathological features in patients.
  
  
  RESULTS
  Expression of PER1 mRNA and protein in OSCC was significantly reduced compared with that in adjacent noncancerous tissue (P < 0.05). Expression of PER1 protein in oral phase III-IV SCC specimens was significantly lower than that in phase I-II specimens (P < 0.05), and stage T(1)-T(2) patients expressed significantly higher levels of PER1 protein than T(3)-T(4) patients (P < 0.05). Expression of PER1 in patients without lymph node metastasis was significantly higher than that in those with lymph node metastasis (P < 0.05). PER1 protein expression showed no significant correlation with patient gender and age, or with degree of tumor cell differentiation (P > 0.05).
  
  
  CONCLUSIONS
  Changes in PER1 expression may play an important role in the development, invasion, and metastasis of OSCC, and may also provide novel ideas and methods for investigation of the occurrence, development, and targeted treatment OSCC.
authors.affiliation: Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Chen
authors.forename: Kai
authors.initials: K
authors.lastname: Yang
authors.forename: Ning-Bo
authors.initials: NB
authors.lastname: Zhao
authors.forename: Dan
authors.initials: D
authors.lastname: Zhao
authors.forename: Dan
authors.initials: D
authors.lastname: Chen
authors.forename: Chun-Rong
authors.initials: CR
authors.lastname: Zhao
authors.forename: Hong
authors.initials: H
authors.lastname: Tang