孕激素-VEGF-C信号通路在子宫内膜癌淋巴结转移中的作用与分子机制

Lymph node metastasis represents a major route for the spreading of endometrial carcinoma (EC). Lymph node positivity is an important prognostic factor for patients' five- and ten-year disease-free survival. Despite significant efforts to improve the treatment and diagnosis, statistical data indicate that deaths caused by EC are rising steadily. Surgical treatment of endometrial carcinoma by hysterectomy is effective for low grade lesions that are limited to the uterus. However, lymph node spread and distant metastasis often lead to relapse and a deteriorated patient survival. The molecular mechanisms leading to the lymph node metastasis of endometrial cancer are not fully understood. Progesterone deficiency and loss of progesterone receptor (PR) have long been known as critical etiological factors for the progression of EC, however, their role(s) in endometrial cancer lymph node metastasis has not been examined. We have been investigating the connection between VEGF-C expression and metastasis, and our preliminary data pointed to the negative regulation of VEGF-C by progesterone-PR pathway. In this study, we propose: First, to determine if VEGF-C and/or lymphangiogenes is involved in endometrial cancer metastasis to the regional lymph nodes using both clinical specimen and mouse uterine orthotopic animal model. Secondly, to investigate the mechanism underlying the regulation of VEGF-C by progesterone-PR using promoter reporter assay system. This study is based on solid preliminary data, and the in vitro as well as in vivo experimental systems that have been readily established in our pilot study. The study is expected to provide crucial information that will leads to better understanding of the molecular mechanism(s) responsible for the VEGF-C-induced lymphangiogenesis and lymph node metastasis under the progesterone deficiency or loss of PR expression. The new findings will be also useful for the development of novel therapeutic modalities against lymph node-positive endometrial cancers that often present as advanced, progestin-resistant cases. The proposal carries significant novelty, and the strong clinical implications are considered an advantage of this project.

淋巴结转移是子宫内膜癌（EC）的主要扩散途径，严重影响患者预后。目前，EC淋巴结转移的分子机制尚不清楚。孕激素受体（PR）表达缺失的EC常具有淋巴结转移，复发率高和预后差的特点。血管内皮细胞生长因子C（VEGF-C）与淋巴结转移有关。我们观察到孕激素可抑制VEGF-C的表达。作如下假说：因为孕激素抑制VEGF-C的表达，那么孕激素不足或PR丢失可导致VEGF-C的表达去抑制进而导致VEGF-C表达上调，VEGF-C的过表达引起新生淋巴血管生成或引起肿瘤细胞侵袭淋巴血管的侵袭性增加，因而促进了肿瘤细胞的淋巴结转移。本课题拟利用临床标本和动物模型确定VEGF-C是否参与了EC的淋巴转移。同时利用体外荧光酶报告基因系统研究孕激素／PR对VEGF-C 抑制的分子机制。这对于理解孕激素不足或受体缺失情况下VEGF-C的高表达及EC淋巴转移至关重要，也将有希望成为治疗晚期淋巴结阳性EC的新的药物靶点。

淋巴结转移是子宫内膜癌（EC）的主要扩散途径，严重影响患者预后。孕激素受体（PR）表达缺失的子宫内膜癌患者常具有淋巴结转移，复发率高和预后差的特点。 因而研究子宫内膜癌淋巴结转移的分子通路及机理，对提高患者生存率具有重要作用。本课题以孕激素-VEGF-C轴为中心研究对象，采用人肿瘤组织、原位小鼠子宫内膜癌模型及体外基因启动子活性调控模型，旨在研究VEGF-C在EC的淋巴结转移过程中的作用，以及孕激素／孕激素受体对VEGF－C基因表达的调控机制。证实孕激素不足或受体缺失情况下VEGF-C的高表达与EC淋巴转移至关重要，也有助于寻找治疗晚期淋巴结阳性EC的新靶点。课题组首先研究了有关人VEGF-C的表达水平及其与EC淋巴结转移的相关性。在人EC组织TMA芯片中用免疫组织化学方法确定 VEGF-C 蛋白表达水平及淋巴血管密度（LVD）和淋巴血管浸润（LVI）状况。相关性分析显示VEGF-C表达水平和LVD/LVI水平呈正相关性。同时，在体内小鼠原位内膜癌模型上，进一步验证VEGF-C降低而引起的肿瘤淋巴结转移率下降。证实了EC中VEGF-C过量表达参与了肿瘤淋巴血管新生及EC癌细胞的淋巴结转移。此外，利用体外荧光酶报告基因系统研究孕激素／PR对VEGF-C调控的分子机制，实验证明孕激素及受体系统对于VEGF-C的抑制作用。本课题对于理解孕激素不足或受体缺失情况下VEGF-C的高表达及EC淋巴转移至关重要，不仅提供了一个解释孕激素抗肿瘤效应的可能机制，也为特异性阻断EC的淋巴结转移提供新的治疗靶点。这是首次发现孕激素-VEGF-C 轴在EC淋巴转移中的作用机制，虽尚处于初期阶段，也为后期相关工作奠定了坚实的基础。课题组全面完成了本基金项目计划书中预期目标，发表研究论文4篇，申请专利3项。