Following are public and technical abstracts for the Stroma and Clear Cell project funded by the Department of Defense Kidney Cancer Research Program (KCRP) for 2017.
Principal Investigator: Leif Oxburgh
Institution: Maine Medical Center
Funding Mechanism: Idea Development Award — Established Investigator
Award Amount: $553,824
Public Abstract
Clear cell renal cell carcinoma (ccRCC) is our 10th most common cancer. Surgical removal of the tumor is the primary treatment for the majority of patients and is curative in over 50% of cases. However, therapeutic options are limited for the large number of patients whose cancer recurs. Chemo- and radiotherapies are ineffective, and the current focus is on inhibitors of specific pathways. In other forms of cancer, the communication between cancer cells and surrounding support tissue known as stroma determines the behavior of cancer cells and their responsiveness to therapies. Because faithful laboratory models of ccRCC are lacking, it has not been possible to critically evaluate the role of the stroma in this type of cancer. We propose to use novel technologies to accurately mimic the tumor environment and to implant laboratory-generated tumors in the cortex of the mouse kidney, the location where human ccRCCs are found. Our goal is to generate faithful, patient-specific replicas of ccRCC with which we can determine the role of stromal cells in promoting aggressiveness of the tumor. In addition to providing an understanding of the role of tumor stroma in determining ccRCC aggressiveness, our work will provide patient-specific tumor models using which drugs can be tested to understand which are most effective. This personalized medicine approach is based on building models using tumor cells derived from surgically removed patient tumors. We also propose to extend this personalized medicine approach to the use of reprogrammed pluripotent stem cells from cancer patients. The proof-of-principle experiment included in our project involves generating the cell of origin for ccRCC from induced pluripotent stem cells with a mutation in a common ccRCC disease gene, VHL. Using this model, we will be able to study early behaviors of these mutant cells in the formation of cancer, which will yield important insights into the origins of ccRCC that may be applicable to disease prevention. This state-of-the-art approach to disease modeling for ccRCC takes advantage of recent years’ progress in understanding how to generate new kidney tissue.
Technical Abstract
Background: Clear cell renal cell carcinoma (ccRCC) is the 10th most common cancer. Surgical removal of the tumor is the primary treatment for the majority of patients and is curative in over 50% of cases. However, therapeutic options are limited for the large number of patients whose cancer recurs. Chemo- and radiotherapies are ineffective, and the current focus is on inhibitors of specific pathways. Broadly, these are targeted to angiogenesis (e.g., Bevacizumab, Sunitinib) or to metabolism (e.g., Temsirolimus). It is anticipated that these drugs target pathways in tumor cells, cancer-associated fibroblasts, endothelial cells, and inflammatory cells. In most cancers, each of these populations plays an important role in determining pathogenesis; in ccRCC the cancer cell – vasculature communication has been the focus of particular attention because of the highly angiogenic nature of the tumor. However, little is known regarding the role of tumor-associated fibroblasts.
Areas of Emphasis: This proposal addresses Microenvironment and Targeted Therapies.
Objective: To study the poorly explored but potentially clinically important influence of tumor fibroblasts on ccRCC aggressiveness we propose to develop an assay system in which tumors will be generated in a controlled manner using primary patient-derived fibroblasts, primary tumor cells, and extracellular matrix (ECM) scaffolding that closely mimics that of the tumor of origin.
Specific Aims
Aim 1: Develop synthetic ccRCC tumors using prototype cell lines
1A. Incorporate tumor-specific ECM into the synthetic tumor scaffold
1B. Adjust biomaterial stiffness to generate a scaffold with high physical fidelity
Aim 2: Determine how ccRCC aggressiveness is influenced by stromal recruitment
2A. Define the influence of fibroblast investment on tumor aggressiveness in vivo
2B. Understand if fibroblasts participate in transformation of VHL-mutant epithelial cells
Study Design: We can efficiently generate ccRCC tumor models using porous 3D silk scaffolds with and without fibroblast incorporation, and these synthetic tumors are morphologically similar to patient tumors. Silk scaffolds allow for a controllable 3D structural support for cell growth and cell-cell interactions that is easily modified to mimic the native biophysical and biochemical environment. We have developed conditions for the growth of kidney tissue in the cortex of the kidney where we see vigorous vascularization by the host. We propose to develop an orthotopic tumor-modeling system with the highest possible fidelity by recreating multiple parameters of the tumor of origin such as cellular composition, stiffness of the substrate, and ECM composition. Our project will generate high-fidelity patient-specific 3D tumor models in which patient-derived stromal cells and cancer cells are scaffolded on ECM matched to the tumor of origin.
Innovation: This technological platform will provide a high-fidelity assay system in which we can stringently evaluate the influence of cancer-associated fibroblasts on tumor aggressiveness, and it will also provide a platform for a precision-medicine approach to determining drug susceptibility for individual patients.