LOS ANGELES - A team of scientists at the Keck School of Medicine of USC is looking to some deep sea dwellers to create a better way to develop cancer-fighting therapies. Harnessing the power of the enzymes that give these marine animals the ability to glow, the team created a test that makes it easy for researchers to see whether a therapy is having its intended effect -- killing cancer cells. The results of their study were published in Scientific Reports on Jan. 9, 2018.
"One of the most promising areas in cancer research is immunotherapy, including chimeric antigen receptor-T (CAR-T) cells. It is also one of the most difficult because the methods for testing immunotherapies are not ideal," says corresponding author Preet M. Chaudhary, MD, PhD, professor of medicine at the Keck School, chief of the division of hematology and center for blood diseases, and director for bone marrow transplant at USC Norris Comprehensive Cancer Center. "Radioactive chromium release assay is the gold standard for testing whether an immunotherapy kills cancer cells. This method is expensive, complicated and requires special disposal practices. Other available methods also suffer from limitations and don't allow scientists to rapidly screen immunotherapeutic agents to find the best candidates."
The team set out to develop a simple, precise and inexpensive test based on marine animal luciferases, the enzymes responsible for bioluminescence. A group of small crustaceans and deep sea shrimp were selected for their bright bioluminescence, and their luciferases became the basis of the test, called the Matador assay. Engineered to get trapped inside cells, the luciferases leak out of cells when they die, causing a visible glow. The level of luminescence can then be measured with a luminometer.
To test the Matador assay's effectiveness at measuring cell death, several different types of cancer cells, including chronic myelogenous leukemia, acute myelogenous leukemia, Burkitt's lymphoma and solid tumors, were treated with a variety of immunotherapies, including CAR-T cells, bispecific T-cell engagers and monoclonal antibodies. Results showed that the assay was so sensitive that it could detect the death of a single cell, a level of sensitivity far exceeding existing assays. Chaudhary's lab has since developed more than 75 cancer cell lines expressing the marine luciferases and used them successfully in the Matador assay to develop next-generation CAR-T cells.
The assay is fast, inexpensive and can be performed in a 384-well plate format, saving time and reagents.
"In our hands, the Matador assay can detect cell death in as little as 30 minutes, which can ultimately translate to more expedient treatments for patients getting cellular immunotherapies such as CAR-T cells," Chaudhary says.
The Matador assay has many potential applications in biomedical research and cellular therapy manufacturing, he explains.
"It could potentially play a role in screening other types of anticancer agents or even measuring environmental toxins."
About the Keck School of Medicine of USC
Founded in 1885, the Keck School of Medicine of USC is among the nation's leaders in innovative patient care, scientific discovery, education and community service. It is part of Keck Medicine of USC, the University of Southern California's medical enterprise, one of only two university-owned academic medical centers in the Los Angeles area. This includes Keck Medical Center of USC, composed of Keck Hospital of USC and USC Norris Cancer Hospital. The two world-class, USC-owned hospitals are staffed by more than 500 physicians who are faculty at the Keck School. The school has more than 1,750 full-time faculty members and voluntary faculty of more than 2,400 physicians. These faculty direct the education of approximately 800 medical students and 1,000 students pursuing graduate and postgraduate degrees. The school trains more than 900 resident physicians in more than 50 specialty or subspecialty programs and is the largest educator of physicians practicing in Southern California. Together, the school's faculty and residents serve more than 1.5 million patients each year at Keck Hospital of USC and USC Norris Cancer Hospital, as well as USC-affiliated hospitals, Children's Hospital Los Angeles and Los Angeles County + USC Medical Center. Keck School faculty also conduct research and teach at several research centers and institutes, including the Eli and Edythe Broad Center for Stem Cell Research and Regenerative Medicine at USC, USC Cardiovascular Thoracic Institute, USC Institute of Urology, USC Mark and Mary Stevens Neuroimaging and Informatics Institute, USC Norris Comprehensive Cancer Center, USC Roski Eye Institute and Zilkha Neurogenetic Institute.
In 2017, U.S. News & World Report ranked the Keck School among the top 35 medical schools in the country.
For more information, go to keck.usc.edu.
Hittu Matta, PhD, assistant professor of research medicine, Ramakrishnan Gopalakrishnan, PhD, research associate, and Sunju Choi, PhD, research associate, also contributed to this study.
This study was supported by the National Institutes of Health under award number R01DE025804. Approximately 5 percent of the project's funding was federally funded. Ninety-five percent of the project's funding was not federally funded. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.