Unravelling the immunogenicity of CLnA-triggered ferroptosis on cancer cells through macrophage activity

Details

Supervisors

Larondelle, Yvan

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries, à finalité spécialisée

Abstract

Cancer is one of the most important leading causes of death worldwide. It is estimated to account for 19.3 million new cases and approximately 10 million deaths in 2020. Cancer is an abnormal and uncontrolled growth of cells caused by multiple genomic alterations. The transformation of healthy cells into cancer cells requires the acquisition of at least six specific properties. One of these specificities is that tumours are composed of a repertoire of recruited stromal cells and extracellular molecules that contribute to the development of the so-called tumour microenvironment. It has been shown to be the major cause for the loss of efficacy of immunotherapy and chemotherapy due to the immunosuppressive character of the cells constituting it. Macrophages are one of the cell types present in the tumour microenvironment. Two subtypes of macrophages, M1 and M2 co-exist. They are respectively pro- and anti-inflammatory. Some evidence has shown that tumour macrophage depletion leads to an increased efficiency of immunotherapy, suggesting M2 macrophages to be promising target for cancer therapy. Since then, many immuno-oncology treatments have been under development, targeting different properties of tumour-associated macrophages. Punic acid (PunA) and docosahexaenoic acid (DHA) are two respectively conjugated and non-conjugated polyunsaturated fatty acids, known to induce ferroptosis in cancer cells. Ferroptosis is a non-apoptotic cell death that is triggered by an iron-dependent accumulation of lipid peroxides and is suggested to be pro-inflammatory through potential activation of macrophages. In addition, prostate cancer is known to be particularly dependent on fatty acid uptake. Based on these facts, the objective of the present work is to investigate the impact of fatty acids, either in their free form or in the form of a lysate derived from prostate cancer cells treated with fatty acids, on the phenotype and activity of both M1 and M2 macrophages. Two prostate cancer cell lines were used as a model, namely PC3 and 22Rv1. Monocytes were polarized into either M1 or M2 macrophages and several treatments with fatty acids and prostate cancer cell lysates were then applied on macrophages. The impact of the treatments on macrophages was measured through RT-qPCR and viability assays. RT-qPCR was used to assess the effect of the treatment on the gene expression of M1 and M2 macrophage markers while the viability assay assessed the cytotoxicity of these treatments. Three conditions showed encouraging results. The addition of PunA 30 µM led to a rise in the expression of TNF-α by M1 macrophages, suggesting an increased pro-inflammatory activity. The lysates from PC3 cells treated with DHA 100 µM induced a significant increase in the expression of HLA-DR, a M1 receptor involved in the activation of T cells, responsible for the destruction of cancer cells. Finally, the lysate of PC3 cells treated with PunA 30 µM triggered a significant decrease in the expression of two genes of M2 macrophages (i.e. CCL22 and fibronectin), which are considered as tumour-favouring molecules. However, these experiments need to be repeated to further confirm the observed trends. In addition, evaluation of gene expression on other immune cells, such as cytotoxic T cells and dendritic cells, and in vivo studies could help to confirm these promising results.