Colorectal cancer is a devastating disease, ranking as the third most commonly diagnosed US cancer and second leading cause of cancer death. There have been only incremental advancements in the treatment of metastatic colorectal cancer so an urgent unmet medical need exists to design and develop new drugs. The central challenge has been to validate novel drug targets and to generate new therapies that disrupt these molecular targets. While protein kinases are among the most popular molecular cancer targets, the 22 oncogenic human protein tyrosine phosphatases that are implicated in cancer have not received suitable attention and none have therapeutically attractive inhibitors. Phosphatases clearly have a non-redundant role in cancer as well as participate in adaptive responses to oncogenes and therapies. Validating a protein tyrosine phosphatase as a molecular target for colorectal cancer and helping to develop small molecules as leads for the treatment of colorectal cancer would have an enormous impact. There is growing evidence that Protein Tyrosine Phosphatase 4A3 (PTP4A3;a/k/a PRL-3) is involved in cancer progression and metastasis. Further target validation and information about small molecule inhibitor interactions are needed. This innovative proposal brings together an experienced multidisciplinary team that will use x-ray crystallography to understand small molecule inhibitor interactions and exploit a recently generated animal model and cells to address these challenges. If successful, this proposal will generate new reagents and information that will enhance our understanding of the role of PTP4A3 in cancer biology and facilitate the design and development of an entirely new class of anticancer agents. In this interdisciplinary approach, we propose two innovative and complementary Specific Aims.
Specific Aim 1 : Determining the interactions of small molecule ligands with PTP4A3.
Specific Aim 2 : Define the functional role of PTP4A3.

Public Health Relevance

This Exploratory/Developmental R21 Grant fulfills the goals outline in the FOA for PAR-13-146. (R21) funding opportunity because it would support the development of tools that should lead to an entirely new approach for the treatment of cancer. The proposal will validate as a molecular target an attractive but poorly understood phosphatase that is linked to colorectal and other forms of cancer. It will also provide critical information required for the design of new drugs targeting this protein.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Exploratory/Developmental Grants (R21)
Project #
Application #
Study Section
Special Emphasis Panel (ZCA1-RPRB-O (O1))
Program Officer
Misra, Raj N
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Virginia
Schools of Medicine
United States
Zip Code
Lazo, John S; Sharlow, Elizabeth R (2016) Drugging Undruggable Molecular Cancer Targets. Annu Rev Pharmacol Toxicol 56:23-40
Salamoun, Joseph M; McQueeney, Kelley E; Patil, Kalyani et al. (2016) Photooxygenation of an amino-thienopyridone yields a more potent PTP4A3 inhibitor. Org Biomol Chem 14:6398-402