Using High-Precision Signaling Activity Imaging to Personalize Ras Pathway Inhibition Strategies in Neurofibromatosis
Abstract
To build a healthy, functioning body, individual cells need to communicate effectively during development. One of the major routes of communication is the Ras biochemical pathway, which allows cells to receive messages from neighboring cells and then turn on the appropriate genes at the right time. Neurofibromatosis type 1 (NF1) results when a key off-switch for the Ras pathway, the NF1 protein, is disabled by a mutation. Because the NF1 protein normally acts as an off-switch for Ras, such mutations result in an overactive Ras pathway, which then fails to transmit the proper signals. These NF1 mutations are highly similar to mutations found in some cancers, which also affect the same communication network. However, unlike cancer, NF1 patients carry these mutations in all or most of the cells in their body, and thus all the mutated cells cannot be removed like a tumor -- they must be treated systematically. Recently, new hope for treating NF1 has come from data that drugs originally created to treat cancer may have highly beneficial effects in NF1 patients, if used at the correct dose. These drugs limit the flow of signals through the Ras pathway, helping to normalize the overactive signaling caused by the NF1 mutations. Treatment with the right combination of these drugs could suppress developmental defects and prevent or slow tumor formation. However, extreme caution is needed; these are powerful drugs that can be harmful at the high doses used to treat cancers. Therefore, what is now needed is a way to precisely tune the amount, timing, and types of drug used to restore normal signaling in NF patients. Our lab has developed a unique tool that allows us to determine, with unprecedented precision, exactly how cellular messages pass through the Ras pathway, and also to test which drugs are most effective at restoring the correct signals. This tool is a real-time imaging platform that can read out the activity of the Ras pathway in living cells. Up until now, researchers have studied Ras with methods that destroy the cells under study each time they are measured, requiring a large number of samples and severely limiting the amount of data that can be collected. Our method allows thousands of cells to be measured intact and simultaneously under many different conditions, providing over 10,000 times more data with the same amount of time and effort as the older methods. This work has already revealed a highly surprising new fact about the Ras pathway: Unlike a standard biochemical pathway, it is activated in digital pulses that appear to be essential for transmitting information. We have also observed that different inhibitors of the Ras pathway affect these digital messages in very different ways. Thus, this technology opens an entirely new window on the intricate details of Ras-based communication. In this study, we will use our imaging technology to compare cells carrying normal and NF1 mutations. We will determine for the first time precisely how the messages carried by Ras differ between healthy and disease-affected individuals: Does the defect lie in a signal that is too strong, which needs to be turned down? Or does the signal affect how long the signal stays on, requiring a therapy to help it turn off sooner? We will answer these questions, and, importantly, test how each of the available Ras-pathway drugs affects these signals, allowing us to identify the drugs that best restore the normal signal. The answers to these questions may be different for each individual NF patient, or for each cell type within a patient, so we will compare multiple types of cells and cells from multiple patients. Within the next 3 years, this project will provide the information needed to choose the Ras pathway drugs that are most effective at the cellular level, and this information can be used to help guide clinical trials that are now being planned and initiated. Because Ras pathway inhibitors are likely to b
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 31, 2017
- Source ID
- W81XWH1610085
Entities
People
- John G Albeck
Organizations
- United States Army
- University of California, Davis