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Unraveling metabolic settings and targeting metabolic enzymes with selective lethality in BRAF and NRAS mutant melanoma tumors

Final Report Summary - METABOSET (Unraveling metabolic settings and targeting metabolic enzymes with selective lethality in BRAF and NRAS mutant melanoma tumors)

The METABOSET Project Final Report
by Mileidys Perez ( and Juan A Recio (

Melanoma is the most aggressive type of skin cancer. Although surgery is very effective at its early stages, if becomes metastatic the survival at five years is less that 5%. Therapeutic alternatives to metastatic melanoma are very limited. Despite the progress that has been made in developing targeted therapeutic strategies for BRAFV600E mutant melanomas (60% of cutaneous melanomas), these cells eventually develop resistance. On the other hand, the melanomas that harbour activating NRASQ61L mutations (15-20%) have not a clear therapeutic alternative.
Tumour cells, particularly melanoma cells, have to deal with high levels of reactive oxygen species (ROS). ROS attack products from the methionine salvation route and lipid peroxidation leading to the formation of three endogenous apoptogenic aldehydes: methional, malondialdehyde (MDA) and 4- hydroxynonenal (HNE). As highly electrophilic compounds, aldehydes rapidly form adducts with cellular nucleophiles (e.g. glutathione, nucleoproteins implicated in chromatin condensation, proteins of the mitochondrial permeability transition pore involved in controlling the release of cytochrome c, etc..). The accumulation of these events leads to apoptosis unless compensated by a high activity of ALDH1, ALDH2 and/or ALDH3 that oxidize these aldehydes to non-apoptogenic carboxylic acids.
Increased ALDH activity is a surrogate marker for human and murine cells with increased tumorigenic potential, particularly resistant to death-induced signals, and suggested to be responsible for tumour reappearance and metastasis. In melanoma, cells with these abilities are marked also by a high enzymatic activity of ALDH.
The METABOSET project was focused on understanding the metabolic settings of BRAFV600E and NRASQ61L mutant melanomas to find novel therapeutic alternatives to treat melanoma tumours. For this, the following tools were used: (i) genotyped patient-derived cell lines (NRASQ61L, BRAFV600E and NRAS/BRAF wild type), (ii) patient-derived xenograft mouse models that recapitulates patient tumours phenotypically and genetically, (iii) complex syngenic melanoma mouse models and (iv) inducible genetic systems together with unique specific inhibitors for ALDHs.
In the context of the project, we demonstrated the specific advantages that ALDH1A1 and ALDH1A3 isoenzymes confer to melanoma cells, including refractoriness to cell death. Our findings were confirmed in a cohort of patients affected with melanoma and from a large scale analysis of molecular and genetic repositories. We showed also for the first time, the potential of these two isoenzymes for the diagnosis of benign nevi, malignant lesion and metastasis. More importantly, our data from different preclinical studies that contemplated NRASQ61L and BRAFV600E mutated melanomas indicated the therapeutic efficacy of targeting both, ALDH1A1 and ALDH1A3 in melanoma mouse models using either specific inhibitor for these two isoenzymes or blocking their enzymatic activity with a genetic approach.
Data that has emerged from METABOSET enrich the basic knowledge about mechanisms controlling survival of melanoma, and more importantly, it is of highly interest on the area of translational medicine as well as to the pharmaceutical industry and other companies. The results of this research open the possibility to use specific inhibitors of ALDHs for the treatment of both, NRASQ61L and BRAFV600E mutated melanomas.
It is known that the histopathological diagnosis of cutaneous melanocytic lesions may be difficult to assess. Results from METABOSET suggest also that ALDH1A1 and ALDH1A3 can be used as diagnostic biomarkers in clinical practice to better identify normal or dysplastic nevus from melanoma in situ, at early stages. The expression pattern of ALDH1A1 and ALDH1A3 can be predictive too for the evolution of the disease and for stratifying patients for therapies based on specific ALDH inhibitors.
In the United States more than 45,000 cases of melanoma occurred each year and this rate have been steadily increasing (7-15%) during the last fifteen years. In Europa, over 30 000 deaths from melanoma were estimated in 2010, with CEE having the largest share (35•5%) among the four geographical European regions. This incidence rates all over Europe continue to increase, which translates into an ever increasing burden for general practitioners, dermatologists and surgeons. The applicability of the knowledge provided by METABOSET is timely and relevant for the whole society as it can benefit the diagnosis and the treatment of malignant melanomas.

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