title: [Circadian rhythm variation of the clock genes Per1 and cell cycle related genes in different stages of carcinogenesis of buccal mucosa in animal model].
abstract: OBJECTIVE
  To investigate the expression and circadian rhythm variation of biological clock gene Per1 and cell cycle genes p53, CyclinD1, cyclin-dependent kinases (CDK1), CyclinB1 in different stages of carcinogenesis in buccal mucosa and its relationship with the development of buccal mucosa carcinoma.
  
  
  METHODS
  Ninety golden hamsters were housed under 12 hours light-12 hours dark cycles, and the model of buccal squamous cell carcinoma was established by using the dimethylbenzanthracene (DMBA) to smear the golden hamster buccal mucosa. Before the DMBA was used and after DMBA was used 6 weeks and 14 weeks respectively, the golden hamsters were sacrificed at 6 different time points (5 rats per time point) within 24 hour, including 4, 8, 12, 16, 20 and 24 hour after lights onset (HALO), and the normal buccal mucosa, precancerous lesions and cancer tissue were obtained, respectively. HE stained sections were prepared to observe the canceration of each tissue. Real time RT-PCR was used to detect the mRNA expression of Per1, p53, CyclinD1, CDK1 and CyclinB1, and a cosine analysis method was applied to determine the circadian rhythm variation of Per1, p53, CyclinD1, CDK1 and CyclinB1 mRNA expression, which were characterized by median, amplitude and acrophase.
  
  
  RESULTS
  The expression of Per1, p53, CDK1 and CyclinD1 mRNA in 6 different time points within 24 hours in the tissues of three different stages of carcinogenesis had circadian rhythm, respectively. However, the CyclinB1 mRNA was expressed with circadian rhythm just in normal and cancer tissue (P < 0.05), while in precancerous lesions the circadian rhythm was in disorder (P > 0.05). As the development of carcinoma, the median of Per1 and p53 mRNA expression were significantly decreased (P < 0.05), yet the median of CDK1, CyclinB1 and CyclinD1 mRNA expression were significantly increased (P < 0.05). The amplitude of Per1, p53 and CyclinD1 mRNA expression was significantly decreased as the development of carcinoma (P < 0.05), however the amplitude of CDK1 mRNA expression was significantly increased (P < 0.05). In addition, there was no significant difference in the amplitude of CyclinB1 mRNA expression. The time that the peak expression value of Per1 and CDK1 mRNA appeared (Acrophase) in precancerous lesions was remarkably earlier than that in normal tissues, but the acrophase of p53 and CyclinD1 mRNA expression was remarkably delayed. Moreover, the acrophase of CDK1 and CyclinB1 mRNA expression in cancer tissues was obviously earlier than that in normal tissues, yet there was no significant variation in acrophase of Per1, p53, CyclinD1 mRNA expression between normal tissues and cancer tissues.
  
  
  CONCLUSIONS
  The circadian rhythm of clock gene Per1 and cell cycle genes p53, CyclinD1, CDK1, CyclinB1 expression remarkably varied with the occurrence and development of carcinoma. Further research into the interaction between circadian and cell cycle of two cycle activity and relationship with the carcinogenesis may providenew ideas and methods of individual treatment and the mechanism of carcinogenesis.
authors.affiliation: Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Tan
authors.affiliation: Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, 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 400016, China; Email: cqfyyk@aliyun.com.
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 400016, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Chen
authors.affiliation: Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Tang
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D016203:CDC2 Protein Kinase / Q000235:genetics*; D063646:Carcinogenesis; D002273:Carcinogens; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D002453:Cell Cycle; D002940:Circadian Rhythm / Q000235:genetics*; D006224:Cricetinae; D056744:Cyclin B1 / Q000235:genetics*; D004195:Disease Models, Animal; D015972:Gene Expression Regulation, Neoplastic; D019940:Genes, bcl-1; D016158:Genes, p53; D008647:Mesocricetus; D009061:Mouth Mucosa; D009062:Mouth Neoplasms / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D056950:Period Circadian Proteins / Q000235:genetics*; D011230:Precancerous Conditions / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D002273:Carcinogens; D056744:Cyclin B1; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D015127:9,10-Dimethyl-1,2-benzanthracene; D016203:CDC2 Protein Kinase