microRNA-128在肺癌发生过程中对VEGF家族因子及其受体的调控作用和相关机制的实验研究

The formations of new blood vessels and lymphatic vessels mediated by the vascular endothelial growth factor（VEGF） family and their receptors (VEGFRs) are crucial for tumour cells to remove metabolic waste and provide oxygen and nutrients, a critical process that allows tumour cells to enter a state of uncontrolled proliferation, invision and metastasis.Studies indicated that the expressions of a lot of growth factors and their receptors mediated angiogenesis and lymphangiogenesis were regulated by the key factor- - microRNA.Recently, What should be pay more attention is the new advancement in the functional research of vascular endothelial growth factor-C,a member of the VEGF family. Our previus studies had shown for the first time that tumour cell proliferation, invasion and lymphatic metastasis involve VEGF-C-mediated autocrine stimulation mechanisms on the regulation of the expression of other factors of VEGF family and their receptors, and that VEGF-C may act in multiple ways to promote tumour progression. Simutanously, our studies showed for the first time that microRNA-128 showed significantly lower expression in human non-small cell lung cancer than nomal human fetal lung fibroblast cell line, and suggested that microRNA-128 could decrese expression of VEGF-C through direct 3′UTR interactions. Those results have not been reported worldwide. This study was desigend on the basis of our previous works. Regarding non-small cell lung cancer(NSCLC) as the research subject, and combining the analysis numbers of clinical specimens, we would like to adopt many experimental technologies, such as immunological technique, pathology tecnique, molecular biology and transgenic mice, to investigate the role and mechanism of microRNA-128 on the occuring and developing of NSCLC.The study will not only put forward a new concept and new mechanism on the occuring and developing of NSCLC,but also provide new scientific foundation and new approach for cancer therapeutics which take microRNA-128 as the potential therapeutic targets designed to target pathological angiogenic and lymphangiogenic signalings.

VEGF家族因子及其受体介导的血管、淋巴管新生是肿瘤细胞获得氧和养分的关键步骤，更是肿瘤细胞无限增殖、侵袭和转移的始作俑者。研究显示，介导血管和淋巴管生成的许多生长因子的表达受控于更关键的因素-microRNA。值得关注的是，2011年VEGF家族中VEGF-C的研究取得了新进展，其中我们前期研究首次报道了VEGF-C除参与淋巴管、血管生成外，还影响VEGF家族其他因子及受体的表达，是肿瘤增殖、侵袭和转移的关键因子。同时，我们首次发现miR-128在肺癌细胞中表达异常，而且与VEGF-C的表达存在靶向关系，这一结果国内外未见报道。本课题以前期工作为基础，以肺癌为研究对象，结合临床标本，采用免疫学、分子生物学技术和转基因小鼠等手段，探讨miR-128对肺癌的致病作用及相关机制。新机制和概念的提出，不仅丰富了肺癌发生机制的理论内容，而且为临床将miR-128作为肿瘤治疗的靶点提供新的科学依据。

近期的研究显示，microRNAs是重要的的基因调控因素，参与许多的生物学过程，可作为肿瘤的抑制因子或者促进因子。因此，microRNAs的表达水平可作为肿瘤检测和预后评估的重要生物标记物。本项研究，证实了miR-128在肺癌细胞株和非小细胞肺癌组织中表达下调，并且与非小细胞肺癌的分化程度、病理分期和淋巴结转移相关。异常的miR-128高表达可明显抑制肺癌细胞株的体外增殖、克隆形成、迁移和侵袭能力，并且诱使细胞发生G1期细胞阻滞和凋亡发生。更重要的是，miR-128的高表达促使了肿瘤细胞VEGF-C的表达下调和VEGF-C 3'UTR荧光素酶活性降低，导致了调控肿瘤血管和淋巴管生成的VEGF家族因子VEGF-A, VEGFR2和VEGFR3的表达下调，使得ERK, AKT和p38信号通路的磷酸化活性降低，进而阻断了上述信号通路。而且，本研究的裸鼠移植瘤治疗实验证实，体内恢复miR-128的高表达，可抑制肿瘤的体内生长及血管和淋巴管的生成。因此，本研究证实miR-128在非小细胞肺癌的发生中起着重要作用，至少可以通过靶向调控VEGF-C表达来同事控制肿瘤的血管和淋巴管生成及相关信号通路，体内恢复miR-128的高表达有望成为非小细胞肺癌治疗的治疗策略。