Identifying Circulating Tumor Cells that Become Dormant Disseminated Tumor Cells

原发肿瘤脱落的播散性肿瘤细胞可能在远处组织中潜伏很长时间。 在它们被激活以形成转移之前的一段时间。最近我们小组的工作表明， (I)造血干细胞(HSC)的植入和(Ii)前列腺癌(PCA)转移到 骨髓依赖于许多相同的分子。事实上，我们最近已经证明了 转移性前列腺癌直接与HSC争夺利基市场。我们还开发了技术 以及允许使用抗人白细胞抗原(HL A)从骨髓中分离人DTCs的模型。 假设：诱导HSC休眠的分子也可诱导转移性PCa细胞休眠 可用于识别DTC。 建议的目标如下： (1)识别循环肿瘤细胞(CTCs)和成功的DTCs之间的差异。 假设：休眠DTC具有不同于CTC和分离型DTC的特征。 我们将确定受体的表达水平，已知的受体调节归巢、倒伏和生长，以及 将从我们的小鼠异种移植模型中获得的CTCs和DTC上的基因表达谱。然后, 这些分析将用来自PCa患者的CTCs和DTC重复进行。 (2)确定进入休眠状态的DTC的特定亚型。 次级假说：处于休眠状态的DCs最终有能力形成肿瘤。 首先，我们将通过在休眠的DTCs中植入 免疫受损的小鼠。接下来，我们将确定致瘤表型，同时确定这些 细胞还具有集落形成能力和耐化疗能力。最后，我们将确定我们是否可以 用Gas6(见项目2)或IL-6(见项目3)操纵这些细胞的休眠状态。 (3)确定DCs休眠的分子机制。 次级假设：与膜联蛋白2(AnxaZ)的结合是DCs休眠的关键 我们已经证明，成骨细胞表达的Anxa2是一种关键分子，对于 PCA，这表明PCA通过Anxa2/Anxa2r轴获得来自生态位的信号。因此， 我们将确定阻断PCA上的Anxa2r是否可以防止进入休眠状态。此外，我们还观察到 当PCA与Anxa2结合时，PCA上Gas6受体Ax1的表达增强。因此， 我们将确定参与Anxa2对Ax1诱导作用的信号通路。 这些发现将直接支持项目2，该项目将确定骨内膜HSC生态位如何调节 肿瘤休眠，以及项目3，重点是什么导致休眠细胞的激活。

Disseminated tumor cells (DTCs) shed from a primary tumor may lie dormant in distant tissues for long periods of time before they can be activated to form metastases. Recently work in our group has shown that (i) the engraftment of hematopoietic stem cells (HSC) and (ii) prostate cancer (PCa) metastasis to the marrow are dependent on many of the same molecules. In fact, we have recently demonstrated that metastatic PCa directly competes with HSC for occupancy of the niche. We have also developed technology and models that permits isolation of human DTCs from marrow using anti-human leukocyte antigens (HLA). Hypothesis: Molecules that induce HSC dormancy also induce dormancy of metastatic PCa cells and can be used to identify DTCs. The following aims are proposed: (1) Identify the differences between circulating tumor cells (CTCs) and successful DTCs. Sub Hypothesis: Dormant DTCs have different profiles from CTCs and dividing DTCs. We will determine the expression levels of receptors, known to regulate homing, lodging and growth, and gene expression profiling on CTCs and DTCs that will be obtained from our murine xenograft model. Then, these analyses will be repeated with CTCs and DTCs obtained from PCa patients. (2) Identify the specific subtype of DTCs that become dormant. Sub hypotheses: DTCs that become dormant have the capability to eventually form tumors. First, we will determine the frequency of tumorigenic cells in the dormant DTCs by implanting into immunocompromized mice. Next, we will determine the tumorogenic phenotype while determining if these cells also have the colony-forming ability and chemo-resistant ability. Finally, we will determine if we can manipulate dormant state of these cells with GAS6 (See Project 2) or IL-6 (See Project 3). (3) Determine the molecular mechanism that is critical for DTCs to become dormant. Sub hypotheses: The binding to annexin 2 (AnxaZ) is critical for DTCs to become dormant We have demonstrated that Anxa2 expressed by osteoblasts is a crucial molecule for the niche selection of PCa, This suggests that PCa obtain the signals from the niche through the Anxa2/Anxa2r axis. Therefore, we will determine if blocking Anxa2r on PCa prevents becoming dormant. In addition, we have observed that when PCa bind to Anxa2, the expression of Axl, the receptors for GAS6, is enhanced on the PCa. Thus, we will determine signaling pathway that is involved in the effects of Anxa2 on Axl induction. These findings will directly lend support to Project 2 which will determine how endosteal HSC niche regulates tumor dormancy, and Project 3 which focuses on what leads to activation of the dormant cells.