Desarrollo de metodologías ómicas para el estudio y diagnóstico precoz del cáncer de pulmón

Abstract

Lung cancer (LC) is one of the most common deaths from neoplasia in the world, causing more than 1,300,000 deaths per year. The 5-year survival comprises 65% when the disease is diagnosed in early stages, decreasing to 10% in advanced stages. Therefore, the search for biomarkers capable of early detection of LC, as well as capable of evaluating its progression, is a challenge of great interest in medicine. In this sense, omics methodologies are very powerful analysis tools that allow determining a large number of molecules (metabolites, proteins, metals bound to proteins). These biomolecules can undergo alterations in response to a disease, so they could serve as diagnostic markers. Thus, in this Doctoral Thesis, three omics methodologies (metabolomics, ionomics and metallomics) based on mass spectrometry have been applied to human biological samples of patients with lung cancer in order to identify altered biomolecules in this disease that can serve as biomarkers. In order to achieve greater metabolite coverage, a "non-target" metabolomic platform was optimized based on two analytical techniques: gas chromatography (GC-MS) and direct infusion (DI-MS) coupled to mass spectrometry. This platform was applied to samples of patients with LC, control patients and patients with various non-cancerous lung diseases such as chronic obstructive pulmonary disease COPD. The samples used in the study were samples of blood serum, urine, and as the main novelty of the study, samples of bronchoalveolar lavage (BAL), of which there was no background in the literature. Therefore, the metabolic profiles of LC patients with those of healthy people were compared statistically by means of the multivariate analysis of partial least squares discriminant analysis (PLS-DA) in order to find significantly different metabolites between the groups. The PLS-DA analysis was also applied to compare the occurrence of altered metabolites in patients with COPD and evaluate their possible relationship with LC. Likewise, the metabolomic differentiation between early and advanced stages of the disease was evaluated. On the other hand, an ionomic methodology based on ICP-QQQ-MS was developed for multielemental determination in samples of serum, urine and BAL in order to evaluate the distribution of trace elements and toxic metals in LC. In addition, serum samples were subjected to a fractionation method for the separation of the high fraction (HMM) and low fraction (LMM) molecular mass and determine the concentration of elements in each fraction. Finally, a metallomic methodology based on the isotope dilution technique by ICP-QQQ-MS was developed to determine the concentration of 3 important selenoproteins present in serum: glutathione peroxidase (eGPx), selenoprotein P (SELENOP) and selenoalbumin (SeAlb). This methodology also allowed the separation of low molecular mass species of selenium. Thus, the application of these metabolomic, ionomic and metallomic platforms in different biological samples from patients with LC has allowed the study of the alteration of metal metabolites and selenium biomolecules associated with LC disease, giving place to new contributions to the pathology of this disease.