Experimental Program

     The primary goal of the Douglass Lab’s Experimental Program is to better understand the cell-type selectivity of FDA-approved oncology drugs. Our working hypothesis, is that differential killing of immune and cancer cells is primarily due to the differential expression of drug-transporter and metabolism enzymes . Effectively, these enzyme act like “armor” by reducing the amount of drug that can “gets in” to the cell. These enzymes are highly promiscuous and confer a “Multi-Drug Resistance” (MDR) phenotype, which makes the chemical-specificity of this “armor” challenging.

As illustrated in Figure 2, our experimental work employs a combination of live-cell kinetic assays (biochemistry) coupled with quantitative Structure Activity Relationship (qSAR) studies (medicinal chemistry). Our biochemical work focuses on measuring enzymatic parameters (e.g. kcat, Km, IC50) for the most commonly used cancer-therapies. Our medicinal chemistry work combines the results of these assays with chemo-informatics to define the chemical properties that make drugs “armor piercing.” Several critical features of our assay include:

  • Live-Cell Kinetic Measurements:   to directly compare drug-sensitivity to drug-efflux and maximize relevance of kinetic measurements to in vivo conditions (J. Biol. Chem. 2017, 292, 15838)
  • Multiple-Measurement & Single-cell Technologies:  to generate rich data-sets amenable to evaluation of complex kinetic mechanisms (Mol. Pharm. 1999, 56, 791)
  • Mathematical and Statistical Modeling to facilitate data-processing and fitting to multi-parameter kinetic models (Science, 2005, 308, 523)

Figure 2. Methods like flow cytometry allow investigators to measure enzymes and substrates simultaneously (A) across millions of cancers cells (B) generating information-rich data-sets well suited for kinetic-analysis (C)