昼夜节律通路DEC2/NPAS2/VEGFC调控胃癌淋巴转移的机制

Disruption of circadian rhythms in humans is related to increased cancer risk. The complex network of communication between the circadian clock and tumorigenesis is only beginning to be unraveled. DEC2 is the first sleep-related gene discovered by scientists. A mutation in DEC2 is associated with a human short sleep phenotype. Also, DEC2 is closely related to lymph node metastasis of gastric cancer, but its mechanism is not clear. In our previous studies, we found a series of genes differentially expressed between HGC27-NC cells and HGC27-DEC2 overexpression cells by microarray detection. Both circadian gene NPAS2 and lymphatic metastasis related molecule VEGFC was decreased in HGC27-DEC2 overexpression cells. These results were also verified in tumor cells. More importantly, overexpression of DEC2 inhibited proliferation and tube formation of HLECs. Therefore, we propose that DEC2 is essential for inhibiting lymph node metastasis in gastric cancer, through regulating NPAS2 and VEGFC expression. We will use Luciferase reporter gene systems and chromatin immunoprecipitation assay to clarify the possible mechanism by which DEC2 regulates NPAS2 and VEGFC; we will analyze the correlation between DEC2, NPAS2 and VEGFC in clinical tumor samples, gastric cancer cell lines and animal models, revealing the significance how circadian pathway DEC2/ NPAS2 /VEGFC acts in lymph node metastasis of gastric cancer. We hope that some of our studies may help us understand the new regulation mechanism of DEC2/ NPAS2/VEGFC pathway, and have significant clinical implications in gastric cancer

昼夜节律紊乱与肿瘤发生发展直接相关。昼夜节律核心基因DEC2是科学界发现的首个调节睡眠的基因，DEC2突变被证实可以显著缩短睡眠时间。我们前期发现节律基因DEC2与胃癌淋巴转移密切相关，但其在调控转移过程中作用的分子靶点尚不明确。芯片筛选发现，DEC2过表达后，另一节律基因NPAS2和淋巴转移关键分子VEGFC表达下调；生物信息学分析显示NPAS2启动子区存在DEC2的结合位点，VEGFC启动子区存在NPAS2结合位点；细胞实验证实三者表达具有相关性。我们提出“昼夜节律核心通路DEC2/NPAS2/VEGFC调控胃癌淋巴转移”的假说，拟通过构建过表达及干扰慢病毒载体，结合荧光素酶报告基因检测、ChIP等技术，在临床肿瘤样本、胃癌细胞系及动物模型上，探索昼夜节律通路DEC2/NPAS2/VEGFC在胃癌淋巴转移中的作用及调控机制，为相关靶点应用于临床转化医学奠定理论基础。

昼夜节律紊乱与肿瘤发生发展直接相关。昼夜节律核心基因DEC2是科学界发现的首个调节睡眠的基因，DEC2突变被证实可以显著缩短睡眠时间。本项目研究发现，DEC2能通过NPAS2抑制HLECs的增殖和小管形成能力；昼夜节律紊乱的裸鼠荷瘤后，DEC2、NPAS2、VEGFC不同时间点的表达具有昼夜节律性；肿瘤组织中DEC2、NPAS2、VEGFC三者表达具有相关性。肿瘤休眠细胞的长期存在是肿瘤复发、转移和化疗耐药的一个重要原因，导致肿瘤难以根治。我们研究还发现昼夜节律基因DEC2能明显抑制肺癌细胞增殖能力，使细胞发育停滞于G0/G1期而进入休眠状态，另外，DEC2促进肺癌细胞侵袭迁移，但克隆形成能力下降；转录组测序分析发现：过表达DEC2后，肿瘤休眠关键调控分子NR2F1存在差异表达。干扰DEC2表达后，P62表达明显下调，LC3II表达增加，自噬激活。这些数据提示DEC2可能通过自噬在肺癌细胞转移性休眠中发挥重要作用。.在本研究中，我们还通过生物信息学分析、临床病理研究、建立细胞及小鼠肺腺癌实验模型，发现FKBP4促进了肺腺癌的恶性进展，为肺腺癌的临床辅助诊断及靶向治疗提供新思路。