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2024BIOMED005
Public access from
12/12/2025
Doctoral thesis

Identification of novel targets in hepatocellular carcinoma immune cell populations using proteomics and functional genomics

  • 2024

PhD: Università della Svizzera italiana

Hepatocellular carcinoma
Tumor microenvironment
Cancer immunotherapy
CD8+ T cells
AFAP1L2
Mass spectrometry-based proteomics
English Understanding the mechanism of immune cells within the tumor microenvironment (TME) is essential for advancing our understanding of tumor escape strategies as well as for developing novel immunotherapeutic approaches. Tumors create an immunosuppressive environment that may dampen effector immune cell functions. Cancer immunotherapy aims at reversing these immunosuppressive effects and restore immune cell functionality by yielding a cytotoxic T cell mediated immune response. To improve current therapeutic approaches, a thorough understanding of the molecular changes within key immune subpopulations in the TME is essential. To address this, we employed high-resolution mass spectrometry to profile the proteomes of immune cells isolated from the tissue of tumor, liver, and blood of 48 hepatocellular carcinoma (HCC) patients undergoing surgical resection. We found that tumor-associated macrophages (TAMs) upregulate the sphingosine-1-phosphate-degrading enzyme SGPL1, which dampens their inflammatory features and reduces their anti-tumor functions. In parallel, we discovered that the adaptor protein actin filament associated protein 1 like 2 (AFAP1L2), is significantly upregulated in chronically stimulated CD8+ T cells within the TME. Notably, AFAP1L2 depletion in CD8+ T cells improved cell viability upon chronic stimulation, enhanced anti-tumor activity, and exhibited a synergistic effect with PD-L1 blockade in mouse tumor models. Building on these findings, we further explored the functional role of AFAP1L2 in human CD8+ T cells by conducting CRISPR-Cas9 knockout studies. Our results reveal that the genetic ablation of AFAP1L2 in CD8+ T cells enhances T cell cytotoxic activity in vitro. In co-culture assays with Jeko-OKT3 cells, AFAP1L2 knockout CD8+ T cells exhibited increased tumor cell killing efficiency compared to control cells, without inducing markers of early T cell exhaustion or altering effector cytokine secretion. This enhanced killing effect was confirmed in a secondary model using NALM6 leukemia cells and the bispecific T-cell engager blinatumomab, where AFAP1L2-depleted CD8+ T cells continued to show improved cytotoxic responses. These results suggest that AFAP1L2 functions as a modulator of CD8+ T cell activity within the TME, limiting their full cytotoxic potential. Our results highlight AFAP1L2 and SGPL1 as potential therapeutic targets for modulating immune cell function in HCC, contributing to a broader understanding of immune regulation in cancer. This thesis thus provides insight into the molecular landscape of immune cells within the TME, offering potential avenues for therapeutic intervention aimed at reactivating immune responses in immunosuppressive environments.
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  • English
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Medicine
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green
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https://n2t.net/ark:/12658/srd1332132
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