Organoid modeling of pre-metastatic niche formation in the liver by primary colorectal tumor secreted factors

点击翻译按钮获取中文摘要

Metastatic disease remains the primary cause of cancer-related deaths. In colorectal cancer (CRC), the liver is the primary site of metastases; and, the majority of patients diagnosed with CRC die as a result of their hepatic metastases. This provides a powerful motivation to study the mechanisms behind the complicated metastatic cascade, hopefully leading to novel approaches for intervention. However, studying the biological mechanisms that contribute to metastatic disease has been difficult. One such target for research that has arisen recently is the pre-metastatic niche (PMN), which forms distant from the primary tumor, but creates favorable environments for metastasizing cells to take hold. Studying the PMN is challenging, as in animal models it is nearly impossible to predict when changes might happen in the PMN, and after identification of metastases, it is too late. A clinically-relevant in vitro model in which metastasis and the changes to tissues leading up to metastasis can be observed and manipulated would be an invaluable resource for probing these mechanisms and for identifying ways to circumvent them. Our team has now published several papers describing our bioengineered in vitro metastasis-on-a-chip (MOC) platform that is comprised of microfluidic devices and 3D extracellular matrix (ECM) hydrogel-based tumor and tissue organoids. Our objective is to use these tools to identity and pinpoint early changes to the liver PMN that occur because of primary tumor-secreted mediators and assess their contributions to CRC metastasis. We will accomplish this by employing 3D liver, CRC, and bone marrow hematopoietic progenitor cell (BM-HPC) organoids, contained in a microfluidic platform to quantify liver remodeling and BM- HPC recruitment, and in turn, how this remodeling influences the likelihood and kinetics of in vitro metastasis. We hypothesize that within our novel bioengineered in vitro platform, secreted mediators from tumor cell line organoids and patient-derived tumor organoids (PTOs) of varying grade will induce a corresponding spectrum of ECM remodeling, architectural dysregulation, and BM-HPC recruitment, which when heightened, corresponds with increased metastasis. In Aim 1, we will subject primary human liver and BM-HPC organoids to CRC conditioned media, measure hepatic stromal (stellate) and immune (Kupffer) cell activation, and quantify ECM remodeling in terms of composition, architecture, and mechanical properties. As part of this aim, we will dissect out the relative contributions of stellate cells, Kupffer cells, and BM-HPCs to these changes. In Aim 2, our MOC device will include tumor organoids in addition both the liver and BM-HPC organoids and we will assess PMN formation in this dynamic multi-tissue platform. Metastasis from the tumor to liver organoid will be measured. This will enable us to link changes of the PMN to metastatic events. Ultimately, these studies will provide opportunities to identify tumor cell secreted mediators and distinct features of the PMN that could potentially serve as future targets of the early metastatic process prior to becoming incurable as well as biomarkers for prediction of metastasis in patients.