Role of extracellular microenvironment on lung cancer cell metabolism

Lung cancer is the second most prevalent type of cancer with the highest mortality rate among all cancer types. Despite significant progress in cancer drug development and therapeutic strategies targeting cancer metabolism, a lack of understanding about the intricate complexities of the tumor microenvironment continues to hinder effective treatment approaches. This study aims to tackle these challenges by using advanced three dimensional (3D) in vitro cancer models to explore the role of interactions between cancer cells and their microenvironment in regulation of cancer metabolism. Due to limitations in conventional two-dimensional (2D) cultures, this work focused on creating two distinct hydrogel models representing healthy lung tissue and tumor conditions. These models were developed by combining decellularized native lung extracellular matrix with inert or tumor-mimetic biomaterials, aligning with the research objectives. In the first phase of the study, an in-depth analysis of gene expression profiles in lung tumor cells was conducted, comparing metabolic and tumorigenic regulators between 2D culture and the novel 3D healthy lung-mimetic model. The results showed that the 3D healthy-mimetic environment influenced the expression of epithelial-mesenchymal transition (EMT) markers in tumor cells in response to changing glucose levels. The microenvironment also played a significant role in regulating the stemness of tumor cells and affected the expression of metabolic markers, providing valuable insights into cellular behavior and metabolism. The second phase of the research explored the impact of elevated sulfation, mimicking the aberrant glycosaminoglycan increase within the tumor microenvironment, under varying glucose levels on tumor cell behavior. The investigation provided deeper insights into the complex interplay between sulfation, glucose availability, and cellular responses. Increased sulfation in the tumor-mimicking environment significantly affected cell proliferation and metabolic activity, while the effect of glucose levels varied depending on the microenvironmental conditions. The interplay between glucose levels and the expression of EMT markers was also observed, with high glucose in the tumor mimetic environment leading to significant upregulation of mesenchymal markers in tumor cells. The study highlighted the complexity of metabolic regulation in the tumor microenvironment. The last phase of the study focused on investigating the role of the PIK3CA gene as a key cellular signaling regulator in the observed phenomena. Comprehensive analysis of PIK3CA's effect provided valuable insights into the processes influencing cellular responses in the novel hydrogel models under different microenvironmental conditions. The study revealed a significant role of PIK3CA in regulating cell proliferation in tumor mimetic environments, with glucose levels modulating this effect, validated with PIK3CA knock-down cells. High glucose exposure partially compensated for the effects of PIK3CA knockdown, influencing EMT marker expression, stemness markers, and various metabolic pathways in tumor cells. The complex interplay between glucose metabolism, extracellular microenvironment and PIK3CA signaling was evident, offering potential therapeutic targets for PIK3CA-associated cancers. In conclusion, this comprehensive research underscores the importance of sophisticated 3D in vitro cancer models to accurately simulate the tumor microenvironment and investigate cellular behavior. The findings provide valuable insights into cancer cell metabolism, the impact of microenvironmental factors, and potential therapeutic targets, advancing lung cancer treatment strategies.