Certain types of biochemical processes can impair the immune system’s ability to recognize and kill cancer cells. Purdue University’s W. Andy Tao and his associates have developed a new way to study these processes. They demonstrated the validity of their method in experiments involving leukemia and rare liver cancer cell lines.<\/p>\n
Tao and 10 co-authors published the details of their new method Aug. 1 in the Journal of the American Chemical Society. Their work provides a system for tracking and identifying the various types of proteins and an unheralded but widely secreted class of bioparticles called extracellular vesicles (EVs) that can compromise immunotherapy<\/a>.<\/p>\n EVs deliver a wide variety of cargo from one cell to another, including ribonucleic acid (RNA), a biomolecule that plays key roles in cellular and viral processes like protein formation. The new method relies on both RNA-binding proteins and EVs, which biomedical researchers have linked to many types of cancer under abnormal conditions.<\/p>\n “RNA-binding proteins are important since proteins typically do major work for the function of cells,” said Tao, professor of biochemistry and a member of the Purdue Institute for Cancer Research. In recent years, new roles for RNA have been discovered, a trend that is driving many efforts to develop RNA-based tools, profile RNA-binding proteins and determine their functions.<\/p>\n The new method helps identify what kind of RNA-interacting proteins carried by EVs affect immune cells. Tao has an interest in EVs derived from tumors, which deliver RNAs that can influence immune responses while interacting with RNA-binding proteins in recipient cells.\u00a0<\/p>\n “However, systematic profiling of these interactions remains limited largely due to the low-throughput nature of current methods,” Tao and his co-authors reported. The strategies now available for profiling RNA-binding proteins on a large scale were not designed to selectively detect proteins derived from EVs that interact with RNA in recipient cells.\u00a0<\/p>\n The new method addresses that issue. The method labels the RNA with a synthetic organic molecule that responds to ultraviolet light. Exposure to UV light cross-links (chemically connects) any nearby proteins.\u00a0<\/p>\n
<\/p>\n Through the EVs, these labeled RNAs will be delivered into the immune cells. Then we use UV to crosslink the proteins in the recipient cell.”\u00a0<\/p>\n
W. Andy Tao,\u00a0professor of biochemistry,\u00a0Purdue University<\/p>\n
\n<\/p><\/blockquote>\n Isotopically labeling the proteins that come from the recipient cells helps scientists to tell them apart from those contained in the original cells.<\/p>\n Data science requires high-throughput experiments, Tao noted. But along with high throughput comes the need to ensure a low false-discovery rate. “Otherwise, garbage in, garbage out,” he said. “For this high-throughput profiling experiment, we would like to make sure we have a low false-discovery rate. That’s the part we try to control by involving these two labeling steps.”<\/p>\n Tao’s team validated the method’s effectiveness in experiments tracking the interactions between EV RNA-binding proteins and Jurkat T cells<\/a>, a cell line that researchers widely use to study leukemia. Additional tests similarly verified the method’s ability to identify large numbers of EV RNA-binding proteins in immune cell lines infected with human intrahepatic cholangiocarcinoma. These cells, derived from a rare type of liver cancer, carry a mutation<\/a> of biomedical interest because they resist immunotherapy, he said.<\/p>\n Immunotherapy relies on the immune system to recognize and kill cancer cells. Checkpoint proteins play a key role in this process, but their ability to recognize cancer cells can become compromised. EVs carry checkpoint proteins into immune cells, just as they do with RNA-binding proteins. Research in Tao’s lab and elsewhere continues to explore what role EVs may play in similarly compromising immune cells.<\/p>\n “The role of the EV is certainly being recognized more and more,” Tao said.<\/p>\n This research is a part of Purdue’s presidential One Health initiative that involves research at the intersection of human, animal and plant health and well-being.<\/p>\n This project was partially supported by the National Science Foundation and the National Institutes of Health.<\/p>\n Source:<\/p>\n Journal reference:<\/p>\n
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