| Project Detail |
Lung cancer is the leading cause of cancer-related deaths in Switzerland. Radiotherapy is one of the major treatments for non-small cell lung cancer (NSCLC), but resistance often develops and leads to therapeutic failure. Radiotherapy induces an epithelial-to-mesenchymal transition (EMT), which is associated with the emergence of resistance and a significant metabolic rewiring, thereby affecting local and distal immune responses. An exponentially growing number of clinical trials are currently investigating the synergistic potential of radiotherapy and immunotherapy, although the underlying molecular mechanisms remain to be elucidated.Once considered a waste product of anaerobic cellular metabolism, lactate has been identified as a critical regulator of cancer cell proliferation and the tumor microenvironment. Lactate dehydrogenase B (LDHB) catalyzes the conversion of lactate to pyruvate, thereby fueling cancer cell metabolism. However, how LDHB affects radioresistance and the response to immunomodulators in lung cancer has not yet been studied. Our preliminary experiments have shown that silencing LDHB in NSCLC cell lines reduces mitochondrial metabolism, eliminates epithelial subpopulations, sensitizes mesenchymal cells to radiotherapy in vitro, and reduces the initiation and growth of human xenografts. Interestingly, LDHB silencing dramatically activated the signaling pathways associated with an innate immune response. Interestingly, a reanalysis of our data suggests that the EMT status may be the most important underlying factor for the sensitivity of NSCLC cells to silencing of LDHB per se and that specific genotype, i.e., p53 deficiency and/or KRAS activation, only moderately affects sensitivity. Further, silencing LDHB significantly reduced the abundance of several metabolites associated with the repair of oxidative DNA damage, i.e., the main form of DNA damage induced by radiotherapy. We hypothesize that the EMT status of lung cancer cells determines the sensitivity of the whole tumor to LDHB inhibition and therapy. Thus, the aim of this study is to investigate how modulating the EMT status of cancer cells in combination with LDHB silencing affects the response to radio- and immunotherapy and the combination thereof.We plan to apply a modular experimental strategy for this study. In detail, we will take advantage of our existing models:a). in vitro 2D and 3D cancer cell lines and primary culturesb). ex vivo precision-cut tumor slices (PCTS)c). in vivo human lung cancer modelsd). in vivo syngeneic and inducible orthotopic lung cancer modelsDue to the presence of heterogeneous subpopulations, the EMT status and the composition of the tumor microenvironment have to be analyzed at the single-cell level. Thus, in addition to our established analysis protocols, we will mainly rely on multicolor flow cytometry or imaging mass cytometry for the analysis.The proposed experiments will allow us to comprehensively expand our knowledge of how the EMT status, e.g., cellular plasticity, of cancer cells affects the sensitivity, metabolism, and microenvironment of lung tumors in response to LDHB silencing in combination with radio- and immunotherapy. Our study will thus contribute to our general understanding of the role of lactate metabolism in tumor biology and will foster our long-term goal of developing new treatments for cancer patients. |
