Mendonsa Alisha M, VanSaun Michael N, Ustione Alessandro, Piston David W, Fingleton Barbara M, Gorden David Lee
Department of Cancer Biology, Vanderbilt University, 2220 Pierce Ave S, Nashville, TN, 37232, USA.
Department of Surgery, Vanderbilt University, 801 Oxford House, 1313 21st Ave. S, Nashville, TN, 37212, USA.
Mol Cancer. 2015 Feb 22;14:49. doi: 10.1186/s12943-014-0282-0.
Non alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases in the United States and worldwide. Our studies have previously shown an increase in metastatic burden in steatotic vs. normal livers using a mouse model of diet induced steatosis. In the present study we aim to identify and evaluate the molecular factors responsible for this increase in tumor burden.
We assessed changes in expression of a panel of matrix metalloproteinases (MMPs) using qRT-PCR between normal and steatotic livers and validated them with western blot analysis of protein levels. To evaluate the role of MMP13 on tumor development, we utilized a splenic injection model of liver metastasis in Wildtype and Mmp13 deficient mice, using either parental or stable Mmp13 knockdown cell lines. Further, to evaluate changes in the ability of tumor cells to extravasate we utilized whole organ confocal microscopy to identify individual tumor cells relative to the vasculature. MTT, migration and invasion assays were performed to evaluate the role of tumor derived MMP13 on hallmarks of cancer in vitro.
We found that MMP13 was significantly upregulated in the steatotic liver both in mice as well as human patients with NAFLD. We showed a decrease in metastatic tumor burden in Mmp13-/- mice compared to wildtype mice, explained in part by a reduction in the number of tumor cells extravasating from the hepatic vasculature in the Mmp13-/- mice compared to wildtype mice. Additionally, loss of tumor derived MMP13 through stable knockdown in tumor cell lines lead to decreased migratory and invasive properties in vitro and metastatic burden in vivo.
This study demonstrates that stromal as well as tumor derived MMP13 contribute to tumor cell extravasation and establishment of metastases in the liver microenvironment.
非酒精性脂肪性肝病（NAFLD）是美国乃至全球最常见的肝脏疾病之一。我们之前的研究使用饮食诱导脂肪变性的小鼠模型表明，脂肪变性肝脏与正常肝脏相比，转移负担增加。在本研究中，我们旨在识别和评估导致肿瘤负担增加的分子因素。
我们使用qRT-PCR评估正常肝脏和脂肪变性肝脏之间一组基质金属蛋白酶（MMPs）的表达变化，并用蛋白质水平的western blot分析进行验证。为了评估MMP13在肿瘤发展中的作用，我们在野生型和Mmp13缺陷小鼠中利用肝转移的脾内注射模型，使用亲本或稳定的Mmp13敲低细胞系。此外，为了评估肿瘤细胞外渗能力的变化，我们利用全器官共聚焦显微镜来识别相对于脉管系统的单个肿瘤细胞。进行MTT、迁移和侵袭试验以评估肿瘤来源的MMP13在体外癌症特征中的作用。
我们发现，在小鼠以及患有NAFLD的人类患者中，脂肪变性肝脏中MMP13显著上调。我们发现，与野生型小鼠相比，Mmp13 - / - 小鼠的转移性肿瘤负担降低，部分原因是与野生型小鼠相比，Mmp13 - / - 小鼠从肝脉管系统外渗的肿瘤细胞数量减少。此外，通过在肿瘤细胞系中稳定敲低肿瘤来源的MMP13，导致体外迁移和侵袭特性降低以及体内转移负担降低。
本研究表明，基质以及肿瘤来源的MMP13有助于肿瘤细胞外渗并在肝脏微环境中形成转移灶。
