LncRNA-HOTAIR介导酸性微环境下胰腺癌细胞侵袭转移的机制研究

Pancreatic cancer(PC) is the most aggressive solid tumor with <5% survival after 5 years. Recent studies suggest that interaction between tumor and its microenvironment act as a dynamic process promoting tumor growth, metastasis and invasion, but the mechanism has not been identified. Pancreatic cancer is characterized by an acidic microenvironment. Our previous results showed that acidic microenvironment enhanced metastasis and invasion of pancreatic cancer cells, while the lncRNA-HOTAIR (long non-coding RNA HOTAIR) was up-regulated. Given that previous reports demonstrated HOTAIR expression in patients has been correlated with enhanced cancer metastasis and has linked to invasiveness and EMT of cancer cells, as well as evidence from our lab demonstrated HOTAIR was over-expressed in pancreatic cancer and related to more aggressive tumor stage, we hypothesize that HOTAIR may be up-regulated in acidic stress and then facilitated the EMT process of pancreatic cancer, leading progression of pancreatic cancer. In this study, we detect the gradient of pH value in pancreatic cancer and normal pancreas and explore the expression of HOTAIR-EMT pathway according to the pH value. Further, microenvironment pH value and HOTAIR-EMT pathway will be regulated to observe the metastasis and invasion of pancreatic cancer cells in vitro or in vivo. Starting from the regulatory role of the tumor microenvironment on metastasis and invasion of pancreatic cancer, our present research will, from the perspective of lncRNAs adaptive response to tumor microenvironment stress, focus on the signal transmission among the acidic microenvironment, lncRNAs and pancreatic cancer cells and explore the molecular mechanism by which acidic microenvironment promotes metastasis and invasion of pancreatic cancer. It will provide novel targets and strategies for research on prevention and treatment of pancreatic cancer.

胰腺癌细胞发生侵袭转移是导致死亡的主要原因。胰腺癌酸性微环境与侵袭转移密切相关，其机制尚未明确。课题组研究发现胰腺癌细胞在酸性条件下发生上皮间质转化（EMT）且侵袭能力增强，同时长链非编码RNA-HOTAIR（lncRNA-HOTAIR）表达上调。文献证实lncRNAs在肿瘤侵袭转移中发挥重要作用。前期研究证实HOTAIR在胰腺癌组织中高表达并能调控胰腺癌细胞EMT。由此推测， HOTAIR可能介导酸性微环境下胰腺癌细胞的EMT，从而促进侵袭转移。本研究拟检测胰腺癌组织及不同酸度培养下胰腺癌细胞HOTAIR-EMT信号通路的表达；调控体内及体外胰腺癌细胞微环境酸度及上述信号通路，观察胰腺癌细胞侵袭转移能力的变化。本研究以胰腺癌酸性微环境与胰腺癌细胞之间的相互作用为切入点，深入探讨了酸性微环境下lncRNAs调控胰腺癌细胞发生侵袭转移的分子机制，为胰腺癌的防治提供新靶点和新策略。

胰腺癌细胞发生增殖侵袭转移是胰腺癌发生发展并导致死亡的主要原因。胰腺癌微环境以及胰腺癌微环境中的基质细胞与胰腺癌细胞上述恶性生物学行为密切相关，然而机制尚未明确。本项目通过体外模拟胰腺癌微环境特点，通过体外体内实验探讨了上述三者间的信息传递方式，进一步阐明了胰腺癌细胞恶性生物学行为转化的分子机制：（1）前期研究证实HOTAIR在胰腺癌组织中高表达并能调控胰腺癌细胞EMT，本项目进一步检测了胰腺癌组织及不同酸度培养下胰腺癌细胞HOTAIR-EMT信号通路的表达变化；调控胰腺癌细胞微环境酸度及上述信号通路，观察胰腺癌细胞侵袭转移的变化，阐明了HOTAIR可能介导酸性微环境下胰腺癌细胞的EMT，从而促进侵袭转移。（2）本项目证实PKM2（丙酮酸激酶M2）在胰腺癌乏血管区域低表达并通过体外模拟胰腺癌低糖微环境发现低糖可以诱导PKM2表达及活性的下降；调控PKM2的表达发现下调PKM2可以通过上调AMPKα1促进低糖环境下胰腺癌细胞的自噬，从而有助于胰腺癌细胞的增殖及存活。（3）本项目证实胰腺癌组织中MIIP（迁移侵袭抑制蛋白）低表达并且过表达MIIP可以抑制胰腺细胞的侵袭转移以及裸鼠成瘤；体外通过模拟胰腺癌低氧微环境发现MIIP在低氧环境中表达下调；通过miR芯片发现低氧环境下胰腺癌细胞高表达miR-646，并且miR-646可通过结合MIIP CDS区抑制MIIP转录；项目进一步证实了低氧微环境下miR-646通过介导MIIP与HIF-1α间的相互作用促进胰腺癌侵袭转移。（4）本项目证实了酸性微环境促进HUVEC细胞发生内皮间质转化，从而增加了内皮通透性促进胰腺癌细胞的转移；通过miR芯片及基因调控，发现MiRNA-548可能通过介导酸性微环境诱导的HUVEC细胞EndMT来调控上述过程。综上所述，本研究以胰腺癌肿瘤微环境、胰腺癌微环境中的基质细胞以及胰腺癌细胞之间的相互作用为切入点，深入探讨了胰腺癌肿瘤微环境调控胰腺癌细胞增殖侵袭转移的分子机制，为胰腺癌的防治提供新靶点和新策略。