Environmental factors impact cell physiology and can also influence drug efficacy, but existing model systems used to study human cells have limitations for understanding these contributions. Our lab has broad interests in addressing this fundamental challenge in the context of human blood cancers and normal cellular components of the immune system.
- Tool Development
Previously, our lab developed a new cell culture medium (human plasma-like medium; HPLM) that contains over 60 polar metabolites and salt ions at concentrations that represent average values reported for normal human plasma (Cantor et al., Cell, 2017). By examining human blood cancer cell lines in HPLM versus standard media, we demonstrated that HPLM has widespread effects on cell metabolism and could also be used to reveal new insights into metabolic regulation and drug efficacy. Recent work led by our collaborators further revealed that HPLM could enhance the relative activation of donor-derived human T cells as well (Leney-Greene et al., iScience, 2020).
Drawing from concepts in reactor design typically associated with chemical engineering, we have also optimized mammalian cell bioreactors to operate as chemostats, which permit cell growth under constant conditions (i.e. steady state). By integrating chemostats with dedicated software, cultures can be tightly controlled for various physicochemical parameters, cell density, and metabolite availability. One key advantage of steady state culture is that phenotypes induced by single perturbations can be studied while holding all other conditions constant, thus minimizing unintended secondary effects.
- Research Areas
By integrating our tools with methods in metabolomics, we are interested in asking how both medium composition and oxygen tension affect the nutrient preferences and metabolic liabilities of different human blood cancer lines. We also hope to understand the context-dependent roles of extracellular metabolites in supporting the growth of these cell types as well.
Forward genetic screens have started to define the genetic dependencies of proliferating human cells and how these vary with genotype or cell lineage. However, there has been little investigation into how the nutrient composition of culture media affects which genes are essential in human cells, and most such screens have been performed in traditional media with little relevance to human blood. By performing CRISPR screens of human cancer lines cultured in HPLM versus traditional media, we identified hundreds of medium-dependent fitness genes that span several cellular processes and vary with cell-intrinsic diversity, as well as with the specific combination of basal and serum components that comprise typical culture media. By pursuing follow-up of hits from our screen results, we hope to uncover new gene-nutrient interactions that offer unique insights into the context-dependent roles of cellular proteins, and further, that suggest new strategies for treating human cancers.
The use of cultured cells remains essential across all efforts in drug discovery and development. Unfortunately, however, over 90% of anti-cancer drugs that survive preclinical testing ultimately fail to gain approval, a major issue often attributed to the limited capacity of culture models to recapitulate conditions in the body. Our group has initiated unbiased compound screens of blood cancer lines in HPLM versus traditional media, and seek to identify and understand new metabolite-drug interactions that underlie conditional cell sensitivity to certain small molecule drugs.
Human T cells undergo dynamic metabolic changes that directly affect their activation, growth, and cell-specific functions. These alterations are particularly relevant in the context of anti-tumor immunity, as T cells traffic to distinct areas of the body and must maintain their functionality in the face of challenging metabolic environments. Since the adoptive transfer of modified immune cells is a promising approach for cancer immunotherapy, there is a growing interest to understand how environmental factors influence T cell metabolism and functional efficacy. However, while existing in vitro and in vivo models have been valuable for identifying metabolic pathways that affect immune cell function, each has limitations for addressing this challenge. By again leveraging tools that we have developed, our group hopes to gain new insights into understanding the influence of environmental factors on various aspects of human T cell physiology.