Researchers at the Institute of Systems Biology (ISB) and the University of California at Riverside have said they have developed a novel technique that enables new insights into cancer biology by enabling researchers to show how fatty acids are absorbed by individual cells.
The team published its study (“Single cell profiling of fatty acid uptake with surface immobilized dendrimers“In the Journal of the American Chemical Society.
Fatty acids, along with glucose and amino acids, are an important source of energy for cell growth and proliferation, and abnormal fatty acid metabolism is often observed in cancer. The laboratories of Wei Wei, PhD, assistant professor at ISB, and Min Xue, PhD, assistant professor at UC Riverside, have collaborated to develop a range of chemical probes and analytical approaches to quantify cellular glucose uptake, lactate production and amino acid uptake, and other cancer-related metabolites .
In contrast to glucose and amino acids, however, the mechanisms underlying the uptake of fatty acids by cells are less well known and difficult to identify. The technical aids for measuring fatty acid uptake at the individual cell level are extremely limited.
“We present a chemical approach to profile the fatty acid uptake in individual cells. We use azide-modified analogs to probe fatty acid influx and surface-immobilized dendrimers with dibenzocyclooctine (DBCO) groups for detection. A competition between the fatty acid probes and BHQ2 azide quencher molecules generates concentration-dependent fluorescence signals, ”the researchers write.
“By integrating this method into a microfluidic-based multiplex protein analysis platform, we have elucidated the relationships between fatty acid influx, oncogenic signaling activities and cell proliferation in individual glioblastoma cells. We found that p70S6K and 4EBP1 correlated differently with fatty acid intake. We have confirmed that the joint targeting of p70S6K and fatty acid metabolism synergistically inhibits cell proliferation.
“Our work provided the first example for the investigation of fatty acid metabolism in the context of protein signaling during single cell dissolution and provided new insights into cancer biology.”
“This work is the first example of the profiling of fatty acid uptake in connection with abnormal protein signals in cancer cells during single cell dissolution and represents an important advance in the single cell metabolism assay,” said Wei Wei, co-author.
To profile fatty acid uptake, the researchers chose a surrogate molecule that was structurally similar to natural fatty acids. This similarity led the cells to accept these surrogates like the native ones. The scientists then report that they used a unique dendrimer molecule to accurately quantify these surrogates from individual cells.
When applying this new single-cell tool to a brain cancer model, the researchers found that fatty acid uptake is regulated differently by two downstream effectors of the Mammalian Target of Rapamycin (mTOR), a critical regulator of cell proliferation and protein synthesis. The results showed a compensatory activation of the fatty acid metabolism with oncogenic inhibition or weakening of the glucose metabolism in these brain tumor cells and uncovered a novel combination therapy that targets this bioenergetic flexibility in order to synergistically block tumor growth.
“This novel tool opens up new ways to study how fatty acid metabolism affects biological systems. It also inspired us to develop more metabolic probes for single cell analysis, ”noted Min Xue, co-author of the article.