title: Daily rhythm variations of the clock gene PER1 and cancer-related genes during various stages of carcinogenesis in a golden hamster model of buccal mucosa carcinoma.
abstract: BACKGROUND
  Recent studies have demonstrated that the clock gene PER1 regulates various tumor-related genes. Abnormal expressions and circadian rhythm alterations of PER1 are closely related to carcinogenesis. However, the dynamic circadian variations of PER1 and tumor-related genes at different stages of carcinogenesis remain unknown. This study was conducted to investigate the daily rhythm variation of PER1 and expression of tumor-related genes VEGF, KI67, C-MYC, and P53 in different stages of carcinogenesis.
  
  
  METHODS
  Dimethylbenzanthracene was used to establish a golden hamster model of buccal mucosa carcinogenesis. Hamsters with normal buccal mucosa, precancerous lesion, and cancerous lesion were sacrificed at six different time points during a 24-hour period of a day. Pathological examination was conducted using routine hematoxylin and eosin staining. PER1, VEGF, KI67, C-MYC, and P53 mRNAs were detected by real-time reverse transcriptase polymerase chain reaction, and a cosinor analysis was applied to analyze the daily rhythm.
  
  
  RESULTS
  PER1, VEGF, C-MYC, and P53 mRNA exhibited daily rhythmic expression in three carcinogenesis stages, and KI67 mRNA exhibited daily rhythmic expression in the normal and precancerous stages. The daily rhythmic expression of KI67 was not observed in cancerous stages. The mesor and amplitude of PER1 and P53 mRNA expression decreased upon the development of cancer (P<0.05), whereas the mesor and amplitude of VEGF, KI67, and C-MYC mRNA increased upon the development of cancer (P<0.05). Compared with the normal tissues, the acrophases of PER1, VEGF, and C-MYC mRNA occurred earlier, whereas the acrophases of P53 and KI67 mRNA lagged remarkably in the precancerous lesions. In the cancer stage, the acrophases of VEGF and C-MYC mRNA occurred earlier and later, respectively, compared with the normal stage.
  
  
  CONCLUSIONS
  Variations in the daily rhythm characteristics of the clock gene PER1 and tumor-related genes VEGF, KI67, C-MYC, and P53 correlate with the development of cancer. Additional studies might provide new insights and methods to explore carcinogenic mechanisms and cancer treatment.
authors.affiliation: Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China.
authors.forename: Hua
authors.initials: H
authors.lastname: Ye
authors.affiliation: Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China.
authors.forename: Kai
authors.initials: K
authors.lastname: Yang
authors.affiliation: Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China.
authors.forename: Xue-Mei
authors.initials: XM
authors.lastname: Tan
authors.affiliation: Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China.
authors.forename: Xiao-Juan
authors.initials: XJ
authors.lastname: Fu
authors.affiliation: Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China.
authors.forename: Han-Xue
authors.initials: HX
authors.lastname: Li
keywords: PER1; carcinogenesis; circadian rhythm; clock gene; tumor