Differentiating between the tumor microenvironment and inflammation in order to use immune cells as living cell diagnostics for early cancer detection

Abstract

Recent advances in the field of synthetic biology have enabled the use of macrophages as living cell diagnostics for early cancer detection. Presently, macrophages have been engineered to be macrophage sensors, which produce a reporter signal upon activation of the ARG1 promoter—an event which will occur in the tumor microenvironment (Aalipour et al., 2019). Incorporation of Boolean logic gates can help refine the specificity of this sensor, to ensure that it is only activated in the tumor microenvironment and not in inflammatory or wound healing environments. In order to do this, it is necessary to identify genes that can be used as markers that are differentially specific to tumor microenvironments compared to inflammatory microenvironments. Because tumor microenvironments are commonly infiltrated with M2-polarized macrophages and inflammatory environments are commonly infiltrated with M1- polarized macrophages, assessing relative gene expression from M1 and M2 type macrophages could be a useful avenue for identifying genes to be used in Boolean logic gates for enhancing the specificity of the previously developed macrophage sensor. First, macrophages must be polarized to the M1 and M2 phenotypes, and second, quantitative real time PCR must be used to identify genes that are upregulated in either M1s or M2s.