The Role of TIMPs in Cell Growth, Tumor Progression and Metastasis

主要活动/具体目标。我们正在进行的研究工作的主要目标是深入了解TIMP家族成员，特别是TIMP-2成员的基质金属蛋白酶非依赖性活动。为了达到我们的目标，我们确定了以下特定目标：1)检测TIMPs在改变癌细胞体外生长和侵袭潜能中的作用；2)研究TIMPs在体内对原发和转移肿瘤生长的影响；3)研究TIMPs对免疫调节细胞(髓系抑制细胞)向原发肿瘤和转移瘤的募集的影响4)更好地了解细胞间TIMP的摄取和作用。在先前对肿瘤细胞强制表达TIMP-2的实验中，我们观察到了对原发肿瘤生长的抑制。伴随着肿瘤生长抑制的是肿瘤微血管密度计数(CD31或CD34)(衡量抗血管生成效果的指标)的统计显著下降，以及肿瘤细胞凋亡的增加(也可能是由于抑制血管生成)。有些出乎意料的是，我们还观察到在表达TIMP-2的肿瘤中粘着斑激酶(FAK)的减少，以及在表达TIMP-2和ALA TIMP-2的肿瘤细胞中FAK磷酸化(Y397)的显著降低。我们的观察发现，FAK和/或AKT(Protein Kinase B，PKB)在TIMP-2和ALA TIMP-2肿瘤组织中的磷酸化水平降低，主要是因为：1)FAK位于AKT信号的上游，两者都参与调节细胞的迁移；2)TIMP-2和ALA TIMP-2的表达减少了肿瘤细胞的体外迁移。我们先前报道了内皮细胞中FAK的磷酸化减少，在那里它参与了eNOS的活性控制。我实验室的一个主要关注点是检查外源性TIMP-2在小鼠肿瘤模型中的作用。我们正在研究TIMP-2对肿瘤生长和转移的影响，目的是更好地了解可能影响这些过程的机制。这些最新发现表明，TIMP-2对肿瘤和宿主细胞具有多种作用，这些作用结合在一起产生了强大的抗肿瘤活性，可以用于临床。

Major Activities/Specific Objectives. The principal goal of our ongoing research effort is to develop an in depth mechanistic understanding of the MMP-independent activities of members of the TIMP family, in particular TIMP-2. We have identified the following specific objectives to obtain our goals: 1) examine the role of TIMPs in altering the growth and invasive potential of cancer cells in vitro; 2) study to effects of TIMPs on primary and metastatic tumor growth in vivo; 3) study the influence of TIMPs on recruitment of immune-modulatory cells (myeloid-derived suppressor cells (MDSC)) to the primary tumor and metastatic niche4) develop a better understanding of the uptake and role of intercellular TIMP. In prior experiments with forced expression of TIMP-2 in tumor cells we have observed suppression of primary tumor growth. The suppression of tumor growth was accompanied by a statistically significant decrease in tumor microvascular density count (CD 31+ or CD34+), a measure of antiangiogenic effects, as well as by increased tumor cell apoptosis (also possibly due to inhibition of angiogenesis). Somewhat unexpectedly, we also observed a decrease in focal adhesion kinase (FAK) in TIMP-2 expressing tumors and a significant decrease in FAK phosphorylation (Y397) in both TIMP-2 and Ala+TIMP-2 expressing tumor cells. Our observation that both FAK and/or AKT (Protein Kinase B, PKB) phosphorylation is reduced in TIMP-2 and Ala+TIMP-2 tumor tissues is significant in that: 1) FAK is upstream of AKT signaling, and both are involved in regulation of cell migration; 2) TIMP-2 and Ala+TIMP-2 expression reduced tumor cell migration in vitro. We previously reported decreased FAK phosphorylation in endothelial cells where it is involved in control of eNOS activity. A major focus in my lab has been to examine the effects of exogenous TIMP-2 in murine tumor models. We are studying the effects on tumor growth and metastasis with the aim of developing a better understanding of the mechanisms that may affect these processes.These recent findings suggest that TIMP-2 has a variety of effects on both tumor and host cells that combine to produce a potent anti-tumor activity that could be exploited clinically.