Wu Ming-Wei, Xian Li-Jian, Li Xiao-Mei, Pasquale Innominato, Francis Lévi
INSERM E 0354 Chronothérape utique des cancers, Hôpital Paul Brousse and Université Paris XI, 94807 Villejuif Cedex, France.
Ai Zheng. 2004 Mar;23(3):235-42.
BACKGROUND & OBJECTIVE: Anti-cancer effect of 5-Fluorouracil (5-FU) is mediated mainly by inhibition of the thymidylate synthase (TS), while dihydropyrimidine dehydrogenase (DPD) is an initial and a rate-limiting catabolic enzyme of 5-FU. In this study, the mRNA expression profiles of TS, DPD, p53 and c-myc were investigated in mouse liver.
A total of 24 male B6D2F1 mice were involved in this study. All the mice were synchronized with an alternation of 12 h of light (L) and 12 h of darkness (D) (LD12:12) for 4 weeks. Body temperature and rest-activity were monitored with an intra-peritoneal sensor. All the mice were sacrificed at 3, 7, 11, 15, 19, 23 HALO (hours after light onset) respectively and liver samples were obtained and immediately frozen in liquid nitrogen. Total RNA was extracted from the frozen liver samples and one-step real-time quantitive RT-PCR was performed using LightCycler - RNA Amplification Kit SYBR Green I system.
Both body temperature and rest-activity displayed similarly rhythmic patterns with peak times located in darkness, while the trough time was located in the light span. DPD showed a circadian expression in mRNA level with a peak at about 16 HALO (P=0.0012). TS showed a trend for a circadian rhythm, with a peak during light (P=0.079). Neither c-myc nor p53 displayed significant circadian rhythm.
The 24-h patterns in DPD and TS expression were approximately 12 h out of phase, supporting a coordinated regulation of both transcriptional pathways relevant for 5-FU chronopharmacology.
5-氟尿嘧啶（5-FU）的抗癌作用主要通过抑制胸苷酸合成酶（TS）来介导，而二氢嘧啶脱氢酶（DPD）是5-FU的初始且限速分解代谢酶。本研究对小鼠肝脏中TS、DPD、p53和c-myc的mRNA表达谱进行了研究。
本研究共纳入24只雄性B6D2F1小鼠。所有小鼠均在12小时光照（L）和12小时黑暗（D）（LD12:12）交替条件下同步饲养4周。通过腹腔传感器监测体温和静息-活动情况。分别在光照开始后3、7、11、15、19、23小时（HALO）处死所有小鼠，获取肝脏样本并立即液氮冷冻。从冷冻的肝脏样本中提取总RNA，使用LightCycler - RNA扩增试剂盒SYBR Green I系统进行一步实时定量RT-PCR。
体温和静息-活动均呈现相似的节律模式，峰值时间位于黑暗期，谷值时间位于光照期。DPD在mRNA水平呈现昼夜节律表达，约在16 HALO时达到峰值（P = 0.0012）。TS呈现昼夜节律趋势，在光照期间达到峰值（P = 0.079）。c-myc和p53均未显示出明显的昼夜节律。
DPD和TS表达的24小时模式相差约12小时，支持了与5-FU时辰药理学相关的两种转录途径的协调调节。
