Associate Professor Tian Ruijun from the Department of Chemistry at Southern University of Science and Technology (SUSTech), in the collaboration with Dr. Li Pengfei, an assistant professor of the Department of Chemistry, and Dr. Sun Ying, an assistant professor of the department of Biology, made research progress in the field of chemical proteomics research.
The results were published in internationally renowned journal, Proceedings of the National Academy of Sciences (PNAS), entitled “Photoaffinity-engineered protein scaffold for systematically exploring native phosphotyrosine signaling complexes in tumor samples.” This research was mainly completed by Dr. Tian Ruijun’s postdoctoral researcher, Dr. Chu Bizhu, and research assistant He An (co-first author). The Department of Chemistry of SUSTech was the first research unit, with Tian Ruijun, Li Pengfei, and Sun Ying as co-corresponding authors.
Dr. Tian Ruijun is currently the executive board member of CNHUPO, the board member of China Mass Spectrometry Society, the board member of China Chromatography Society and the board member of China Molecular Systems Biology Society. His research interests include bioanalytical chemistry, chemical proteomics, clinical mass spectrometry, and cancer signal transduction studies.
Protein is the most important material composition in the human body. Apart from being the building block of life, there are more than 100,000 protein-protein interactions at any given time. These large numbers of interactions assemble proteins into a wide variety of functional protein complexes that perform and regulate almost all life processes and functions. Through the precise regulation of more than 200 protein post-translational modifications, protein complexes are characterized by temporal and spatial dynamics. For example, tyrosine phosphorylation with very low abundance is recognized and assembled by the Src homology 2 (SH2) domain and is dynamically regulated by tyrosine kinase and phosphatase. It is an important molecular regulatory mechanism for major diseases such as cancer. Many anticancer drugs, such as the most successful targeted cancer drug Gleevac, target these proteins. Proteomic study of tyrosine phosphorylated protein complexes has always been a hot topic in fundamental biology. However, it is difficult to characterize tyrosine phosphorylated protein complexes in vivo in clinical samples, such as tumors, because of the weak binding between proteins and the existence in insoluble cell membranes.
Chemical proteomics is an emerging discipline that combines chemical biology techniques with proteomic analysis techniques to enable in vivo labeling and large-scale analysis of important drug targets and biomarkers. This study developed a chemical proteomics technique to overcome the above challenges and named it as Photo-pTyr-scaffold. The technique seamlessly introduces photoreactive groups and enriched groups for the SH2 domain through chemical probes containing three functional groups, which can achieve covalent bond coupling and affinity enrichment of protein complexes. This significantly improves the ability for enriching and identifying tyrosine phosphorylated protein complexes with dynamic, weak interaction properties in human or animal tissue samples.
Using this chemical proteomics technology, the research group successfully achieved high-selective enrichment and large-scale proteomic analysis of tyrosine phosphorylation proteins and their complexes in human breast cancer tumor samples. Compared with traditional immunohistochemistry, this technology increases the detection sensitivity of the important drug target protein Her2 by about 100 times and is expected to more accurately guide the clinical use of the targeted anticancer drug Herceptin. More importantly, the technology has discovered a potential new drug target PDGFRB for breast cancer patients with negative Her2 expression. Experimental results in animal models of breast cancer indicate that inhibition of this drug target can significantly inhibit breast cancer tumor growth. In summary, this chemical proteomics research strategy is expected to help large-scale discovery of a new generation of cancer drug target proteins and biomarkers.
This research is the third analytical methodology and applied research paper of the Dr. Tian Ruijun’s team following the 2015 PNAS article and the 2018 Analytical Chemistry article for cancer precision medicine. The project was supported by the National Key Research and Development Program Protein Machine Special Subproject, the Natural Science Foundation of China Program, the Guangdong Natural Science Foundation Team Project, and the Shenzhen Science and Technology Commission’s Discipline Layout Project; Shenzhen People’s Hospital provided the relevant clinical samples and analysis.
http://www.pnas.org/content/early/2018/09/05/1805633115
http://www.pnas.org/content/112/13/E1594.long
https://pubs.acs.org/doi/10.1021/acs.analchem.8b00596
Interview:
Q: Chemical proteomics is an interdisciplinary subject that combines chemical biology techniques with proteomic analysis techniques. What do you think is the prospect of this discipline, and what are the advantages of being an interdisciplinary subject?
A: Since many important clinical biomarkers are proteins, and almost all drug targets are proteins, chemical proteomics technology has broad applications in biomedical and precision medical research, and will be helpful for developing innovative drugs. This research provides high-quality proteomics big data support for innovative drug and biomarker discovery. As a highly interdisciplinary subject in chemistry, biology, and proteomics, chemical proteomics can provide analytical selectivity, analytical throughput, and analytical sensitivity over single-disciplinary methodologies.
Q: What kind of impetus will this study have for cancer treatment and prevention in the future?
A: This project has developed Photo-pTyr-scaffold, a chemical proteomics technology with independent intellectual property rights for cancer diagnosis and targeted drug development. The technology is highly versatile and can be used for large-scale quantitative analysis of potential drug target proteins and biomarkers associated with signal transduction in any cancer sample. Taking the precise treatment of breast cancer as an example, Photo-pTyr-scaffold technology can accurately detect the target protein expression level of the first-line targeted antibody drug Herceptin, which has much higher sensitivity than the current clinical gold standard immunohistochemical analysis, which may guide Herceptin’s clinical medication more accurately, and benefit more potential breast cancer patients.
Q: The animal model experiment is mentioned in the article. What are the advantages and disadvantages of lab animals?
A: Innovative anticancer drug development generally involves a preclinical validation phase based on animal models. Compared with the experiments based on model cell lines, animal models can provide the important experimental basis for the drug in vivo and lay the foundation for clinical trials. The disadvantage is often that the animal model used does not fully simulate the actual action of the drug in the human body. Therefore, in this study, we used a mouse model which generates tumor directly in vivo to minimize the drawbacks of animal models.
Q: This research work is mainly done by your research team, Dr. Chu Bizhu, and research assistant He An (co-first author). What are your experiences in guiding students to do scientific research and leading the team?
A: The interdisciplinary research we are engaged in is very challenging. Students need to study experimental techniques in many fields such as chemistry, biology, and medicine. What’s more important is to have strong interest for medical research on cancer, which garners a high level of social responsibility and a desire to explore. Our team members have a high degree of recognition and joint awareness of the above concepts so that this deep interdisciplinary scientific research can be completed in just three years.
