Mechanical stiffening of the interstitial space in the lung – the protein-rich extracellular space between the alveoli and capillaries – plays an important role in modulating epithelial cell behaviors that contribute to cancer and idiopathic pulmonary fibrosis (IPF) disease etiologies. However, the effects of substrate stiffness and breathing-like stretch are not well understood in the context of cancer. In this thesis project, we utilize RNA sequencing to understand how the mechanical properties of extracellular environments modulate cancer related cells. To accomplish this goal, we examined the behavior of lung cancer derived A549 cells, cells that have epithelial lineages, on a biomimetic lung-on-a-chip devices. Importantly, our biomimetic devices allow us to modulate the stiffness of the interstitial space to have soft properties similar to those observed in healthy lung and stiff properties mimicking fibrotic tissues. After growing A549 cells on our biomimetic devices and plastic plate controls, we extracted and purified RNA for mRNA sequencing to examine differential gene expression. Subsequent gene ontology analysis found that differentially expressed genes are involved in cell cycle, metabolism, and cell migration. Connecting these pathways using KEGG analysis we identified pathways of downregulated or upregulated genes related to cancer and metastasis. Based on these results, changes in the interstitial stiffness surrounding A549 cells can change their behaviors and lead to activation of cancer pathways.