studio del metabolismo della lisina e del triptofano in adenocarcinoma polmonare

Lung adenocarcinoma (LUAD) is the most prevalent histological type of lung cancer, with the most common oncogenic drivers being EGFR and KRAS mutations, ALK translocation, and LKB1 deletion. It has been demonstrated that these modifications induce LUAD cells to engage in different metabolic pathways. The majority of studies focused on the metabolism of glucose and glutamine, completely ignoring the function of alternative amino acids like tryptophan and lysine in promoting aggressiveness and immune evasion. Although the importance of lysine and tryptophan metabolism for LUAD onset and progression has been revealed, it is still unclear how these metabolites promote the mitochondrial bioenergetics and dynamics of LUAD cells. In this study, by in silico analysis the Dehydrogenase E1 and transketolase domain-containing protein 1 (DHTKD1) gene was found upregulated in LUAD patients and associated with bad prognosis. This gene codifies for a mitochondrial bottleneck enzyme involved in the breakdown of tryptophan and lysine intermediates. Other preliminary genomic analysis (Gene Set Enrichment Analysis, CIBERSORT-based deconvolution methods, and NanoString spatial analysis on Tissue Microarray) revealed DHTKD1 as a critical regulator of aggressiveness and immune escape, since positively correlated with cell cycle, DNA replication, TCA cycle, whereas negatively correlated with antigen processing and presentation machinery, and immune cells infiltration. To determine the metabolic and molecular mechanisms by which DHTKD1 influences the invasiveness and tumor microenvironment (TME) reshape of LUAD cells, lentiviral vectors have been used to silence this gene in murine LUAD cell lines presenting clinically relevant oncogenic alterations (KRAS G12D mutation and p53 loss of function). Migration, proliferation properties, mitochondrial fitness, oxygen consumption rate (OCR) and survival in hypoxic conditions were evaluated in-vitro, resulting in significant differences only concerning the metabolic behavior of the silenced cells compared with the scramble cells. Briefly, the silenced cells were found to be more oxidative, more energetically stressed and consequently more susceptible to hypoxia. Finally, the silenced and scramble cells were subcutaneously injected into syngeneic mice to evaluate the tumor growth and characterize the immune landscape. Surprisingly, the DHTKD1 low tumors, contrary to the in vitro experiments, revealed a significant reduction of proliferation rate, accompanied by reduced collagen deposits, increased vessel normalization and cytotoxic CD8+ T lymphocytes infiltration.