Reprogramación metabólica e inmunogénica para mejorar la respuesta antitumoral en melanoma y cáncer de páncreas

Resumen

Cancer, a major public health challenge, is characterised by high metastatic and treatment resistance in melanoma and pancreatic cancer, resulting in high incidence and mortality. Metabolism and the immune system are central to the anti-tumour response. Tumour metabolism drives cancer growth and controls processes such as autophagy and drug resistance through protein methylation. Hypomethylating therapies developed by our group have shown anti-tumour activity, suggesting that regulating protein methylation may be effective against cancer. Despite the importance of the immune system in detecting and destroying cancer cells, tumours can evade the immune response, presenting a significant challenge in cancer treatment. Accordingly, the main objective of this PhD Thesis was to study the molecular mechanisms involved in the metabolism, control of protein methylation and anti-tumour immune response in order to design new effective therapeutic strategies against melanoma and pancreatic cancer. Throughout this doctoral thesis, a variety of experimental models were utilised, including melanoma and pancreatic cancer cell lines, as well as mouse animal models. A variety of biochemical techniques were used, such as Western Blot, ELISA assays or protein immunoprecipitation; cell biology techniques, such as viability assays, immunohistochemistry, microscopy, flow cytometry, NK cell isolation or quantification of metabolic parameters; and molecular biology techniques, such as qPCR, DNA cloning, chromatin immunoprecipitation, gene silencing by CRISPR/Cas9 or overexpression of specific genes. In addition, the data obtained were analysed using appropriate statistical tests. The key findings of this Doctoral Thesis are documented in the scientific literatura: First, we observed that acriflavine, a potent inhibitor of HIF-1α dimerisation, alters the metabolism of melanoma cells in normoxia. This treatment reduces glucose availability and suppresses the Warburg effect, while blocking AKT and RSK2 phosphorylation, disrupting protective pathways against oxidative stress. Acriflavin promotes ATF4 degradation and reduces the expression of the transcription factor MITF, a key factor in melanocyte development and oncogene in melanoma. These results indicate that inhibition of HIF-1α by acriflavine could be a novel strategy to treat melanoma, regardless of the presence of hypoxia in the tumour. Second, we studied the role of MITF in the anti-melanoma immune response. We showed that MITF regulates ADAM10, a protease essential for the recognition of melanoma cells by NK cells. In addition to suppressing cell death by NK cells by controlling ADAM10, we also found that MITF can stimulate the T-cell-mediated response. These findings emphasize the capacity of MITF to alter the immune response to melanoma, with important implications for immunotherapy in this cancer. Finally, we evaluated how protein methylation regulates autophagy in pancreatic cancer cells with KRAS mutations. Using a hypomethylating treatment (HMT), we reduced autophagy and activated endoplasmic reticulum stress by altering KRAS signalling. The HMT combination also prevented CRAF activation by modifying the SHOC2-MRAS-PP1 complex. Inactivation of PP2A blocked autophagy, preventing ULK1 activation and restoring cytoplasmic retention of MiT/TFE transcription factors. These results reveal that HMT treatment could be an effective strategy in the treatment of pancreatic cancer. Overall, this Doctoral Thesis highlights the central role of protein methylation processes, cell metabolism, and the immune response in cancer pathology. It also explores the potential for novel therapeutic approaches in the treatment of pancreatic cancer and melanoma.