November 15, 2016
Nanopolymer-modified protein array can pinpoint hard-to-find cancer biomarker
WEST LAFAYETTE, Ind. – A Purdue University biochemist has developed a novel method for detecting certain types of proteins that serve as indicators for cancer and other diseases.
Glycoproteins are formed when sugars attach to and modify a protein. In some cases, a combination of glycoproteins present in a sample of blood or urine could be an indicator of disease or cancer.
But those glycoproteins can be elusive. There has been no antibody to differentiate between them and regular proteins. And the complex and bulky sugar groups can make it difficult for even standard protein-detection antibodies to find their targets.
W. Andy Tao, a Purdue professor of biochemistry, has developed a novel protein array, a high throughput platform to analyze multiple proteins in parallel, for separating glycoproteins from unmodified proteins. Tao also demonstrated its effectiveness for identifying glycoproteins associated with bladder cancer. The findings were published Monday (Nov. 14) in the Journal of the American Chemical Society.
Tao developed a nano-sized polymer, called polyGPA, that attaches to the sugar groups of glycoproteins and brings them to the surface of the protein array. The nanopolymer also repositions the glycoprotein so that the antibodies used to detect unmodified proteins can better reach their targets.
“There are many sugar types and combinations. Sugar modification can be a very important indication of disease state,” Tao said. “A panel of proteins modified by sugars may be an indication of a particular disease.”
Tao said tests showed his method is 17 times to 25 times more likely to identify proteins that might have otherwise been missed in regular testing procedures. He was also able to identify glycoproteins associated with bladder cancer in a urine sample.
“It is possible to use our platform to identify these sugar-modified proteins as a biomarker for bladder cancer,” Tao said.
Tao will work to commercialize his nanopolymer-modified protein array through his company, Tymora Analytical Operations, which operates in the Purdue University Research Park. The company makes the pIMAGO nanopolymer, which can be used to determine whether cancer drugs have been effective against biochemical processes that can lead to cancer cell formation, and polyMAC, a nanopolymer that helps scientists retrieve and study proteins that are undergoing processes related to cancer cell formation.
The study is available to journal subscribers and on-campus readers at http://pubs.acs.org/doi/abs/10.1021/jacs.6b10239
The National Institutes of Health, the National Science Foundation and the Purdue University Center for Cancer Research funded Tao’s work.
Writer: Brian Wallheimer, 765-532-0233, brian.wallheimer@gmail.com
Contact: Natalie van Hoose, 765-496-2050, nvanhoos@purdue.edu
Source: W. Andy Tao, 765-494-9605, taow@purdue.edu
ABSTRACT
Three-dimensionally Functionalized Reverse Phase Glycoprotein Array for Cancer Biomarker Discovery and Validation
Li Pan1, Hillary Andaluz Aguilar2, Linna Wang3, Anton Iliuk3,4, and W. Andy Tao1,2,3,4,5
1 Department of Medicinal Chemistry & Molecular Pharmacology
2 Department of Chemistry
3 Department of Biochemistry, Purdue University, West Lafayette, IN
4 Tymora Analytical Operations, West Lafayette, IN
5 Center for Cancer Research, Purdue University, West Lafayette, IN
Glycoproteins have vast structural diversity which plays an important role in many biological processes and have great potential as disease biomarkers. Here we report a novel functionalized reverse phase protein array (RPPA), termed polymer-based reverse phase GlycoProtein Array (polyGPA), to specifically capture and profile glycoproteomes, and validate glycoproteins. Nitrocellulose membrane functionalized with globular hydroxyaminodendrimers was used to covalently capture pre-oxidized glycans on glycoproteins from complex protein samples such as biofluids. The captured glycoproteins were subsequently detected using the same validated antibodies as in RPPA. We demonstrated the outstanding specificity, sensitivity, and quantitative capabilities of polyGPA by capturing and detecting purified as well as endogenous alpha-1-acid glycoprotein (AGP) in human plasma. We further applied quantitative N-glycoproteomics and the strategy to validate a panel of glycoproteins identified as potential biomarkers for bladder cancer by analyzing urine glycoproteins from bladder cancer patients or matched healthy individuals.
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Darrin Pack, dpack@purdue.edu
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