Cellular and molecular studies in in vitro and post-mortem models for the investigation of new targets in malignant pleural mesothelioma

Malignant mesothelioma (MM) is an extremely aggressive tumor with poor prognosis arising from the serosal linings of peritoneal, pleural or pericardial cavity. After the asbestos fibers’ inhalation and their penetration into pleural space, their interaction with mesothelial and inflammatory cells causes a prolonged progress of tissue damage, repair and inflammation that lead to tumor development. To date, the only approved systemic treatment is platinum-based chemotherapy combined with pemetrexed, with or without bevacizumab while efficacy evidence of second line chemotherapy is lacking. First, this study aimed to assess the lung inorganic fiber content in individuals who were previously exposed to asbestos (either occupationally or environmentally) and subsequently developed mesothelioma, as well as in the general population. This assessment was carried out using electron scanning microscopy with energy dispersive spectroscopy (SEM-EDS). All the subjects in the study had a history of living or working in proximity to an asbestos-cement industry in Broni, Italy, which operated from 1932 to 1993. The findings revealed that asbestos concentrations were consistently lower in the control group, with levels below 100’000 fibers per gram of dry weight (ff/gdw) in this group. In contrast, mesothelioma cases had significantly higher asbestos concentrations. Moreover, it was observed that female subjects had a higher concentration of chrysotile asbestos and thinner asbestos fibers in their lungs compared to male subjects. This difference in terms of fiber composition and dimensional features may indicate varying responses to chrysotile asbestos within the lung microenvironment between genders. Finally, we provided the initial pathological evidence of the impact of the asbestos ban, implemented two decades earlier. We demonstrated a notable reduction in asbestos content in the lungs of individuals after the ban took effect in 2011, indicating a positive outcome of the regulatory measure. Secondly, to advance our understanding of the molecular mechanisms underlying malignant mesothelioma (MM), we conducted whole exome sequencing (WES) on a subset of our samples for which lung content analysis has been performed, identifying frequently mutated genes that have not been previously reported in MM, namely HUWE1, KIAA1109, ADGRV1, and BCORL1. Notably, KIAA1109, ADGRV1, and BCORL1 exhibited distinct mutation patterns among the different histologic subtypes of MM. As it’s already known, frequently mutated genes in MM, such as BAP1, NF2, and CDKN2A, have been link to ferroptosis, a form of cell death triggered by oxidative stress. For these reasons, in the third part of this thesis the response of mesothelial and mesothelioma cells to iron metabolism alterations and the activation of specific pathways of regulated cell death caused by cisplatin and a novel platinum-based compound, Pt(IV)Ac-POA have been investigated. The results demonstrate that Pt(IV)Ac-POA surpasses cisplatin in inducing cell death in mesothelioma cells, activating multiple cell death pathways, including apoptosis, ferroptosis, and autophagy. These r