At the present time, cancer is a leading cause of death worldwide, according to the World Health Organization (WHO). Cancer is a complex multivariable disease, that arises through a multistep mutagenic process. To rationalize this complexity, a set of hallmarks, as well as enabling characteristics, were established which include DNA damage and oxidative stress. For tumorigenesis to occur, cells depend not only on alterations in cellular pathways but also on the extracellular environment. The extracellular matrix (ECM) is a non-cellular structure that is constantly remodeled to control tissue homeostasis and directly impacts the tumor microenvironment playing an important role in tumor malignancy. Abnormal ECM dynamics is associated with many types of diseases. In particular, mutations in ECM and related components have been associated with increased oxidative stress levels in other diseases such as muscular dystrophies, which can lead to DNA damage. Likewise, laminin-α2- related congenital muscular dystrophy (LAMA2-CMD), is characterized by increased oxidative stress. LAMA2-CMD is caused by mutations in the LAMA2 gene, encoding for the α2 chain of laminins 221 and 211. Absence of LAMA2 from skeletal muscle leads to a dystrophic pattern that ultimately results in muscle degeneration and chronic inflammation. Whether LAMA2 mutations may also play a role in cancer is currently unknown. With the resource of cBioportal platform, the frequency of LAMA2 alterations was examined. The analysis showed that alterations in this gene are highly frequent, particularly for skin and colon cancer. Thus, the long-term aim is to establish the relation between absence of LAMA2 and stress phenotypes of cancer, such, DNA damage, and oxidative stress. As a starting point, C2C12 myoblasts were used to analyze pathways linked to DNA damage and oxidative stress. To investigate the effects of absence of LAMA2 in cancer cells LAMA2-deficient A375 melanoma and HCT116 colorectal human cancer cell lines were generated by CRISPR/Cas9 technology. Afterwards, using these in vitro models, pathways linked to proliferation, DNA damage, and oxidative stress were analyzed. Additionally, analysis of ECM components and metabolic pathways was also performed. Overall, data from this project revealed alterations in ECM composition in LAMA2-deficient A375 cells. Increased oxidative stress and DNA damage were also detected in both cancer and LAMA2- CMD in vitro models. Together, these results can generate important tools and knowledge moving forward in our understanding of the role of mutations in ECM components in cancer.

Tese de mestrado, Biologia Evolutiva e Desenvolvimento, 2023, Universidade de Lisboa, Faculdade de Ciências