Targeting Resistance in Colorectal Cancer with a Novel Lineage-Tracking Technology
Abstract
This proposal addresses the Topic Area of Colorectal Cancer. Colorectal cancer is the third most common cancer diagnosed in the United States for both men and women, and the second and third most common cause of cancer-related deaths in men and women, respectively. Here, we also target the Military Relevance Focus Area: "Gaps in cancer prognosis, treatment and/or survivorship" that impact the health of military Service members, Veterans, and their beneficiaries. We propose to develop a new platform for the early identification of chemoresistant cell subpopulations within a patient tumor in order to better match treatments with an individual patient. Recurrence of chemoresistant tumors is the most common cause of cancer mortality. Cancer survivorship care involves managing chronic and intermittent cancer to avoid chemoresistance. Approximately 8% of cancer survivors in the Department of Veterans Affairs system have been diagnosed with colorectal cancer. Efforts towards personalized treatment are complicated by several factors, including the high degree of intratumoral heterogeneity in patient tumors. This means even within an individual patient, different tumor cells respond differently to treatment. Some cells are effectively killed by the therapy and other cells escape. Subpopulations of surviving cells may use different strategies to escape killing by the treatment. Thus, the tumor population will consist of cells with many different gene and protein expression states. These also lead to functional variation in growth rate, metabolism, and sensitivity/resistance to treatments. To improve therapeutic strategies in cancer, new tools are required to measure the contributions of heterogeneous cell populations. Our new tool could potentially reduce delays in identifying the most effective treatment option for an individual patient. DNA barcoding is one way to monitor heterogeneous cell populations. In this approach, each cell in a population is tagged with a unique, heritable DNA sequence. The barcode is copied along with the cell’s genome each time the cell divides and is passed on to all descendants of that cell. Lineage abundance is tracked over time by DNA sequencing. Changes in clonal dynamics after perturbations, such as treatment with a pharmacological agent, can reveal variation in lineage survival or proliferation rate. However, current methods for barcoding are limited because they lyse the sample and do not allow any additional studies with the same lineages, for example, to test alternative treatments or probe the molecular pathways responsible for resistance. Here, we set out to develop a new platform technology, Barcode Assisted Ancestral Specific Expression (BAASE), to combine lineage tracing by barcoding with isolation of lineages of interest. With this new tool, we propose to expose patient-derived colorectal tumor cells to standard first-line treatments and identify lineages that escape treatment. We will then activate a lineage-specific fluorescent marker and isolate the resistant lineages from the initial tumor population. The gene expression state of these resistant lineages will be assessed by RNA Seq and cell sensitivity to other compounds will be measured. Our team includes Dr. Gail Eckhardt, director of the Livestrong Cancer Institute at Dell Medical School, and Dr. Carla Van Den Berg, professor and co-director (with Dr. Eckhardt) of the Developmental Therapeutics Laboratory at the Livestrong Cancer Institute. Dr. Eckhardt has facilitated the collection and transfer of the biospecimen bank that will be a key resource in this proposal. Dr. Van Den Berg oversees the maintenance, culture, and use of these samples. All collaborators are locally based in Austin at the Dell Medical School of The University of Texas at Austin. By developing this novel tool for the assessment of resistant subpopulations in individual colorectal tumors, we will be able to contribute new strateg
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 29, 2018
- Source ID
- W81XWH1810420
Entities
People
- Amy Brock
Organizations
- United States Army
- University of Texas at Austin