University of New Mexico Cancer Center researchers Larry Sklar and Bruce Edwards recently unveiled a powerful new method for discovering molecules that target the regulation of cancer cell life and death. Their high-tech screening approach, detailed in a scientific paper published in the July issue of Nature Protocols, offers cancer researchers at UNM and around the world a potent tool for identifying and characterizing molecules that show promise as the basis for targeted anti-cancer drugs.
"With this new method, we can very rapidly identify which molecules from a host of likely suspects actually have an impact on key proteins that drive the growth of certain cancers," Sklar said. "While the content of this finding is significant, so is the larger context – the use of flow cytometry technology to quickly and cost-effectively detect interactions between biological targets and chemical probes that could prove medically useful. The protocol we've just published is broadly applicable to other types of interactions and illnesses."
Bcl-2 proteins and cell death
In their Nature Protocols paper, Sklar, Edwards and co-authors describe a fast, accurate method for screening a library of small molecules against six proteins in the Bcl-2 family, a group of related proteins that help regulate cell life and death. Identifying those molecules that bind to and inhibit the activity of these proteins in vitro is the first step toward developing a drug that could eventually be used for targeted treatment of certain cancers. Next steps include prioritizing the compounds that work best and validating their efficacy in laboratory and animal experiments.
The six Bcl-2 proteins used as targets in the research play a key role in blocking the signals involved in programmed cell death, or "apoptosis," one of the fundamental mechanisms used by the body to maintain the proper balance between cell growth and death. Like high-stakes tightrope walkers, all living organisms must strike this balance. In healthy human beings, an estimated 10 billion cells die every day to offset the new cells produced by the body's stem cell populations. But with cancer and other diseases, this crucial balance is interrupted. For certain cancers, uncontrolled cell growth is the culprit; for others – including melanoma, breast, prostate and lung cancers – a lack of appropriate cell death appears to drive the disease.
Many cancer cells have been found to have increased expression of one of the six Bcl-2 proteins used by Sklar and Edwards as screening targets; these cancers seem to grow and persist by harnessing anti-apoptotic proteins to "override" the machinery of cell death. Overexpression of such "pro-survival" proteins can also, paradoxically, arise in tumor cells during cancer therapy, allowing them to resist treatment. Finding ways to target – and turn off – selected Bcl-2 proteins is thus a promising line of attack against certain cancers.
UNM Center for Molecular Discovery
The new methodology demonstrates the power of the patented flow cytometry technology it leverages – technology invented in New Mexico by Sklar, Edwards and collaborators at the UNM Center for Molecular Discovery, which Sklar leads. Created in 2005 and funded by $24.5 million to-date from the National Institutes of Health, the UNM Center for Molecular Discovery is one of only nine centers in the nation devoted to identifying, characterizing and prioritizing small molecules – also known as chemical "probes" – that have important uses in biomedical research. Their work has important applications to many areas of disease research, including drug repurposing and the development of personalized treatment approaches.
"The UNM Center for Molecular Discovery is truly a world leader in technology for drug discovery," said Cheryl Willman, director and CEO, UNM Cancer Center. "The work of Drs. Sklar and Edwards and their teams is accelerating progress in designing better treatments for cancer and other diseases, and having an enormously beneficial impact on New Mexico's innovation economy in the process."
The technology that fuels the UNM Center for Molecular Discovery and enabled the Nature Protocols research is a patented device and process called HyperCyt, developed by Sklar and Edwards. It is designed to work with existing high-throughput flow cytometry, a method of analyzing cells and small molecules by suspending them in a stream of fluid and passing them by an electronic detection apparatus. Flow cytometry can make numerous and simultaneous sensitive measurements in a given sample at a rate of tens of thousands of particles per second, allowing researchers to rapidly collect enormous amounts of useful data about the physical and chemical properties of cells or the effects of chemical and biological agents on cell function.
The new HyperCyt technology is designed to automate the simultaneous analysis of multiple populations of particles using sophisticated sampling techniques. This form of flow cytometry is 30 times faster than conventional approaches, accelerating the process of drug discovery and the real-time analysis of molecular interactions and cell response. In the few years since its development, HyperCyt has been applied to identification of possible therapeutic targets on cancer cells, analysis of host-pathogen interactions in various diseases, and molecular discovery that aids in drug repurposing. The technology has given rise to additional patents for new methodologies and molecular discoveries.