The Circadian Variations Of Clock Gene Per1, Per2 And Cancer Related Genes In Buccal Mucosa Carcinoma Of Golden Hamster At Different Stages Of Carcinogenesis

Objectives:To investigate the circadian variation rules of clock gene Per1, Per2 and clock-controlled genes VEGF, Ki67, c-Myc and P53 in different stages of carcinogenesis in buccal mucosa carcinoma and its relationship with the development of buccal mucosa carcinoma.Methods:90 Syrian golden hamsters were housed under 12-hour light/12-hour dark cycles, and the dimethylbenzanthracene (DMBA) was used to establish the model of buccal mucosa carcinoma by smearing the golden hamster buccal mucosa. Before the time DMBA was painted and in 6 weeks and 14 weeks respectively, the hamsters were sacrificed at 6 time points during a period of 24 hours, including 4 (HALO),8 HALO,12 HALO,16 HALO, and 24 HALO, and the normal buccal mucosa, precancerous lesions and cancer tissue were obtained simultaneously. 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, Per2, VEGF, Ki67, c-Myc and P53, and a cosine analysis method was applied to determine the circadian rhythm variation of Per1, Per2, VEGF, Ki67,c-Myc and P53 mRNA expression, which were characterized by median, amplitude and acrophase.Results:The expression of Perl, Per2, VEGF, P53 and c-Myc mRNA in 3 different stages appeared circadian rhythms (P<0.05), the Ki67 mRNA was expressed with circadian rhythm just in normal and precancerous lesions stage (P<0.05), while in cancer tissues the circadian rhythm was disorder (P>0.05).The MESOR of Perl, Per2 and P53 mRNA were significant down regulated with the development of cancer (P<0.05), whereas the MESOR of VEGF、c-Myc and Ki67 mRNA were up regulated (P< 0.05). The amplitude of Perl, P53 mRNA was significantly decreased with the development of cancer (P<0.05), and compared with the normal group, the amplitude of Per2,VEGF, Ki67 and c-Myc mRNA were significantly increased in precancerous lesions and cancer tissue (P <0.05), however, there had no significant difference between precancerous lesions and cancer tissue (P>0.05). In precancerous stage, the acrophase of Perl, Per2, VEGF and c-Myc mRNA were9.66h,2.94 h, 3.72h and 3.86 h earlier than that in normal group, respectively, whereas that of Ki67 and P53 mRNA were 18.28 h and 3.4 h delayed. Compared with the normal group, the acrophase of VEGF and c-Myc mRNA were 8.89h earlier and 16.15h lagged in cancerous stage, respectively, yet there had no significant difference in the acrophase of Per1, Per2 and P53 mRNA.Conclusion:The circadian rhythm characteristics of clock gene Per1, Per2 and clock-controlled genes VEGF, Ki67, c-Myc and P53 mRNA expression have changed obviously with the occurrence and development of carcinoma, further study might provide new ideas and methods for investigation the mechanism of the occurrence and development of cancer and the individualized treatment of carcinoma based on recovering circadian rhythm.