Determining how bacterial presence can impact gene regulation for lung adenocarcinoma cells

ntroduction: Recent studies have discovered lung cancer subtypes to have their own profile of microbiome within the tumor microenvironment. Additionally, the tumor associated microbiome exhibited altered bacterial pathways, suggesting that certain bacterial families are more fit to facilitate tumor progression than others. We believe that there exists a crosstalk between lung adenocarcinoma cells (LUAD) and bacterial cells. Methods and Materials: RNA-seq was performed on LUAD cell lines to understand the paracrine signaling effects that bacterial biomolecules have. From our RNA-seq data, we chose to investigate glycolysis by measuring glucose uptake and lactate production, investigate invasive potential through invasion assays, and measure EMT markers. As lipopolysaccharides (LPS) are found abundantly on the cell wall of gram-negative bacteria and can activate toll like receptor 4 (TLR4), we inhibited TLR4 with C34 to determine the relationship between TLR4 and the phenotypic changes. Finally, to gain a better understanding of the bacterial biomolecules leading to the changes observed, we treated our media with either RNAse, charcoal, or dialyzed molecules > 3kDa. Results and Discussion: From our RNA-seq data, we observed a total of 948 genes upregulated in the presence of E. coli biomolecules. Of the 948 upregulated genes observed in LUAD cell lines incubated in E. coli biomolecules, we witnessed increased expression of Hexokinase II, JUN proto-oncogene, and Snail Family Transcriptional Repressor 1. We verified the elevation of glycolytic enzymes through western blot and saw elevation of 2-deoxyglucose uptake and lactate production in LUAD cell lines incubated in E. coli biomolecules using scintillation counter and lactate luminescence assay, respectively. In addition to E. coli elevating glycolysis in LUAD cell lines, we also saw increase in invasive potential by Boyden chamber. Inhibition of TLR4 did not lead to decreasing the impact of E. coli biomolecules on glycolysis or invasive potential of LUAD. Modulating our E. coli supplemented media with either RNAse, dextran-coated charcoal, or using a spin column to remove biomolecules < 3kDa resulted in changes in HKII and Claudin protein expression. Overall, these findings indicate a direct relationship between E. coli and LUAD, wherein several well-known hallmarks of cancer are upregulated. Future studies would do well in investigating these molecules further and fully understanding the impact of a microbial shift in the tumor microenvironment.