Novel Probes to Target Ras Cancers
Abstract
Our Idea Award proposal concerns the human Ras proteins that are involved in a high percentage of all human cancers. These include pancreatic, colorectal, liver, bladder, and brain cancers, which all are listed as important topic areas to be addressed by the Peer Reviewed Cancer Research Program applications. There are four closely related human Ras proteins, called HRas, Kras4a, Kras4b, and NRas. We will focus on the KRas4b proteins, which are mutated in 80%-90% of all human colorectal and pancreatic cancers, but we expect that our research also will be relevant to the other Ras proteins. Ordinarily, Ras proteins must be delivered to the plasma membranes of cells and be activated in order to transmit their growth signals in cells. When the Ras proteins are mutated, they are constantly activated, and their growth signals cause cells to become cancerous. Although the Ras proteins would seem good targets for anticancer drugs, previous efforts to inhibit the actions of the Ras proteins have encountered problems. A major problem has been that it has proven very difficult to block Ras protein activation sites, and a second problem is that efforts to keep Ras proteins from getting to cell membranes have been unsuccessful. A new approach for stopping Ras proteins from propagating their cancer signals is to stop them from associating each other, or with other cellular proteins. Previous efforts to do this have involved very cumbersome and convoluted methods. Instead, our idea is to use nanobodies to bind and obstruct parts of the Ras proteins that are essential for communicating with other proteins in their signaling pathways. What are nanobodies? They are molecules derived from sharks or members of camel family that are very similar to antibodies, except that they are very small, and are very good at binding to a variety of protein shapes. They also can work inside cells, where Ras proteins are located, and are cheap and convenient to use. Most importantly, millions of different nanobodies directed against the Ras proteins can be generated simply by immunizing a few alpacas with purified Ras protein. Given the remarkable characteristics of nanobodies, our plan is to use purified KRas4b proteins to immunize alpacas and to prepare libraries of millions of nanobodies that recognize different parts of the KRas4b protein, using blood samples that are obtained without jeopardizing the health of the animals. From these millions of nanobodies, we will use two approaches to pick the ones that are most likely block Ras protein functions. One approach is simply to screen for nanobodies that bind most tightly, either to the major part of the Ras protein, or to the part of Ras that binds to membranes. A second approach is to directly analyze the abilities of nanobodies to prevent KRas4b from propagating its cancer signals. To do this, we have devised a novel method for identifying nanobodies that prevent cancer cells from growing. How can the nanobodies we find help in the treatment of cancer? One immediate application will be for the detection of Ras proteins in patients. Although there are ways to examine messenger RNAs that are used by cells to synthesize Ras proteins, the ability to detect the proteins themselves, and potentially differences in the shapes of the proteins, will be useful in diagnosing and distinguishing subtle differences in cancer types that are important in deciding on the best therapies for specific patients. On a longer time frame, nanobodies that obstruct Ras proteins from transmitting their cancer signals will be used to find new drugs that obstruct the Ras proteins in similar ways. It is also possible that using gene therapy approaches, the nanobodies themselves may be useful in stopping harmful Ras signaling pathways. Our proposed research project is directly relevant to the health of active duty Service members and Veterans, because studies have shown that United States military Veterans are at hig
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 10, 2021
- Source ID
- W81XWH2010458
Entities
People
- Eric Barklis
Organizations
- Oregon Health & Science University
- United States Army