微环境组织力学信号调控YAP与HIF-1α促进肝癌细胞形成血管生成拟态的机制

The mechanical factors of tumor microenvironment can promote the progress of tumor. Vasculogenic mimicry (VM) plays an important role in the progress of the tumor.YAP proteins are receptors stimulated by mechanical signals of matrix stiffness, stretch, and cell density. Our preliminary experiments suggest that there is a positive correlation with the expression of YAP and VM in HCC tissues. And HCC cells on stiff matrix can have the ability of forming VM and have stronger abilities of invasion. However, little is known about the influence of matrix stiffness on HCC progression. We hypothesized that microenvironment mechanical forces activates YAP, which can translocate into nuclear and bind HIF-1α to promote its expression and transcription, and activated HIF-1α together with YAP to induce HCC cells to form VM. Thus extracellular mechanical signaling and intracellular biochemical signaling regulate VM formation. In order to prove this hypothesis, we will use HCC cell lines and mouse model, by means of qPCR, western blot, immunofluorescence, lentiviral transfection and RNA interference, and so on, to expore mutual interplay of YAP and HIF-1α, and to confirm mechanisms of VM formation induced by their interaction. This study will lay the foundation for revealing HCC progression and provide new perspectives from mechanical stress.

肿瘤微环境组织力学因素可以促进肿瘤的进展，血管生成拟态（VM）在肿瘤进展中起到了重要作用。YAP是基质硬度、拉伸和细胞密度的力学信号的感受器。我们的预实验提示YAP在肝癌（HCC）中的表达与VM有相关性，硬基质下HCC细胞形成VM与侵袭的能力更强。迄今基质硬度影响HCC进展的机制仍知之甚少。我们假设组织微环境的力学因素激活了YAP，YAP入核与HIF-1α结合并促进其表达与转录，HIF-1α激活后与YAP共同诱导HCC细胞形成VM，这样细胞外与细胞内的信号协同调控VM的形成。为了验证这一假说，我们将通过HCC细胞系和小鼠模型，采用qPCR、蛋白印迹、免疫荧光、慢病毒转染、RNA干扰等手段，从分子、细胞、组织以及动物整体水平等多方面探讨YAP与HIF-1α的相互作用，明确二者促进VM形成的机制。本研究将从力学的新视点为揭示HCC进展奠定基础，从而为临床治疗提供新思路。

YAP1是癌细胞中机械应激反应的基因之一。然而，肝细胞癌（HCC）的发病、进展机制是复杂的，YAP1在肝细胞癌中尚未完全确定。在我们的研究中，YAP1在HCC中的过度表达可以作为严重纤维化的HCC患者预后较差和生存率较低的指标。我们发现YAP1在肝癌组织中的表达与纤维化严重程度呈正相关。血管生成拟态（VM）和严重纤维化是HCC患者的独立预后指标。在这里，我们发现YAP1促进了HCC细胞的迁移、侵袭、VM和肿瘤生长。我们证明了YAP1过度表达和刚性基质可以促进VM形成和VE-cadherin在HCC细胞中的表达。进一步的机制研究表明，HIF-1α的稳定性和活性取决于肝癌细胞中YAP1的蛋白水平。总之，YAP1通过在机械应力下通过直接或者维持HIF-1α的活性来上调VE-cadherin，从而调节VM的形成。靶向沉默YAP1可能通过降低其在抗血管生成拟态中的作用而成为潜在的HCC治疗靶点。