Browsing by Author "Machado, Ana Luísa Marinho da Cunha"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- In silico dessection of the immunomodulatory effects of cholesterol on colorectal cancerPublication . Machado, Ana Luísa Marinho da Cunha; Fernandes, Verónica; Velho, Sérgia; Antunes, LuísCholesterol plays a pivotal role in the progression of tumors, serving as a crucial component for cell membrane formation and the generation of specific proteins and enzymes that stimulate the growth and dissemination of tumor cells. Additionally, cholesterol levels within the tumor microenvironment exert influence over immune responses by hindering the activity of vital components like T-cells and NK-cells, which are indispensable for effective anti-cancer immunity. The primary objective of this research is to investigate whether it is possible to categorize colon cancer tumors based on disparities in cholesterol-related characteristics and whether these groupings correlate with distinct immune profiles. The Cancer Genome Atlas (TCGA) project is an open-access catalog aiming to comprehensively understand the genomic alterations responsible for various cancer types, by encompassing a vast array of molecular data from thousands of patient samples. One of the pivotal advantages of utilizing TCGA data lies in its sheer scale and diversity. By integrating genomic, transcriptomic, proteomic, and clinical data from a multitude of patients, researchers can identify patterns, mutations, and biomarkers associated with specific cancers. Taking advantage of this catalog, we selected TCGA RNA-seq dataset from patients with colorectal cancer (480 tumor colon samples and 167 tumor rectum samples). Firstly, we used the Gene Set Enrichment Analysis (GSEA) tool, a powerful tool employed in bioinformatics and computational biology, to determine the sets of genes and pathways that showed statistically significance. Upon comparing these samples with their corresponding normal adjacent tissues, notable disparities in lipid metabolism were discerned. While cholesterol-related pathways did not rank as the top differentially regulated pathways, we exclusively observed an upregulation of lipid-related pathways in normal adjacent tissue in comparison to tumor tissue within the colon samples. Subsequently, we conducted in-depth analyses to determine whether colon tumors can be stratified based on differences in cholesterol metabolism and whether these variations correlate with disparities in the tumor microenvironment.By using the ssGSEA scores of the pathways related to cholesterol metabolism we employed the k-means method to cluster the samples. Remarkably, colon tumor samples naturally segregated into two distinct groups: one characterized by low expression of cholesterol-related genes and the other exhibiting increased expression. Notably, these groupings exhibited disparities in colon sample staging and the prevalence of molecular subtypes within each category. The group displaying enhanced cholesterol metabolism showcased reduced prolifiv eration, underscoring the significance of tumor microenvironment remodeling. Among the top enriched pathways, were pathways associated with modified antigen presentation, cytotoxic immune responses, and remodeling of the extracellular matrix. These observations were consistent with increased infiltration of immune cells driven by the activation of cholesterol metabolism. However, despite the higher quantity of these immune cells, their activation levels were lower in tumors characterized by upregulated cholesterol metabolism. Comparison of signaling pathways between these groups revealed significant differences in pathways linked to tumor malignancy. In summary, these findings underscore the role of cholesterol metabolism alterations in driving substantial adaptations within the tumor microenvironment. Stratifying colon tumors based on cholesterol metabolism presents a promising avenue, potentially benefiting patients through immunotherapy and cholesterol modulation as adjuvant therapy.
- Influence of KRAS activation in the colorectal cancer immunosurveillance escapePublication . Machado, Ana Luísa Marinho da Cunha; Velho, Sérgia; Oliveira, Maria José; Vieira, MónicaThe imune system as a host defense system watches the cell growth and division, eliminating cells with antigens different from those present in healthy cells. However, some transformed cells have the capacity, through various mechanisms, to escape the immune system. Genomic instability and some mutations are pointed as possible mechanisms supporting the imune surveillance escape,asisthecaseofoncogenicmutations. KRAS mutation is presente in about 40% of cases of colorectal cancer and confers to the tumor a greater potential for malignancy. It is known that KRAS and BRAF mutant cancer cells regulate the recruitment, activation,and differentiation of imune cells,promoting tumor evolution by ensuring leakage to the immune system and increasing the proliferative potential. Few evidences highlight an association between a KRAS mutation and myeloid cells, mainly macrophages and neutrophils infiltration. However, the mechanism which determines this interaction remains unclear. To investigate how the KRAS and BRAF mutations can influence the immune response, either by regulating the expression of immunomodulatory molecules, leading to altered crosstalk between the tumor and the immune system, or by regulating immune cell infiltration. In our work, a series of immunomodulatory molecules were analyzed by flow cytom-etry in a panel of KRAS and BRAF mutant colorectal cancer cells in which KRAS/BRAF was silenced by small interfering RNA. Additionally, the influence of chemotherapy and IFN-Y administration, wich is a non-consensual possible therapy, in the expression of immune checkpoints molecules was also evaluated. It was also performed immunohistochemistry staining of F4/80 to access the in vivo infiltration and distribution of macrophages i the mouse colonic epithelium. Preliminary results suggest that KRAS silencing lead to the alternation of some molecules involved in the crosstalk with the immune system cells, such as macrophages and lymphocytes, as long as BRAF silencing did not cause any alternation. Additionally, in some cases, chemotherpy and IFN-y administrationshowed to have some influence on the upregulation of theses immune molecules expression, wich was impaired by KRAS silencing. On the other hand, KRAS mutation, was not capable to increase the macrophage infiltration in the mouse colon epithelium. KRAS activation seems to be capable of regulating the expression of surface markers, wich can regulate and suppress the immune response against cancer cells, and to influenc the macrophage infiltration whwn combined with another frequent mutation.