DOI: 10.25345/c5028pr68
title: MassIVE MSV000097344 - Nuclear Expulsion Accelerates CD8+ T Cell Dysfunction and Enhances Treatment Resistance
title: Treatment resistance is major challenges in cancer therapy, often following chemotherapy and radiation. While these treatments induce significant apoptotic cell death, the full spectrum of apoptotic signals and their effects on surviving cancer cells remain poorly understood. In previous study, we discovered that apoptotic cancer cells expressing Padi4 undergo nuclear expulsion, releasing a DNA/protein structure (Nuclear Expulsion Products; NEPs) into the extracellular space, which is critical for metastatic outgrowth. However, much remains to be elucidated about the role of nuclear expulsion amidst high levels of cell death during therapy. Here, we confirm that nuclear expulsion occurs in tumor cells after chemotherapy, with Padi4 acting as a nuclear expulsion switch in chemo-treated mouse models. Using this model, we found that Padi4-derived NEPs drive chemo-resistance against cisplatin and gemcitabine. Subsequent immune profiling revealed increased CD8+ T cell infiltration and activation in Padi4high tumors, marked by elevated levels of activation markers such as PD1, GrnzB and IFN-gamma, which were further amplified by cisplatin treatment and led to the exhaustion of CD8+ T cells. Co-culture assay further demonstrated that NEPs directly facilitate CD8+ T cell activation. The importance of CD8+ T cells in the resistant phenotype was further validated through comparisons between immune-competent and -deficient mouse models, as well as a model treated with CD8 neutralizing antibodies (neu Abs). Moreover, proteomic analysis identified vimentin as a major component of NEPs, highlighting its potential as a Damage-Associated Molecular Pattern (DAMP) given the extracellular properties of NEPs. Loss of vimentin in NEPs diminished Padi4-mediated chemo-resistance. Co-culture of CD8+ T cells with vimentin-deficient NEPs or citrullinated vimentin (VIMcit) revealed that extracellular VIMcit is a key mediator of CD8+ T cell activation. We also identified TLR4 as a crucial modulator linking vimentin to CD8+ T cell activation, emphasizing the importance of the TLR4-vimentin axis in nuclear expulsion-mediated chemo-resistance. Furthermore, IFN-gamma was identified as a downstream effector secreted by activated CD8+ T cells, and experiments using IFN-gamma-R-depleted tumor cells or IFN-gamma-neu Abs diminished Padi4 mediated chemo-resistance, implying the importance of IFN-gamma for therapy resistance. Collectively, NEPs elevate CD8+ T cell infiltration and activation, and during therapy, increased cell death generates more NEPs, driving CD8+ T cell hyperactivation. This excessive stimulation leads to CD8+ T cell exhaustion, allowing tumor cells to acquire IFN-gamma-mediated therapy resistance and long-term immune evasion. This research underscores the pivotal role of NEPs in shaping tumor immunity and therapy outcomes, offering a promising new direction in cancer biology and treatment. In summary, our studies provide insight into the molecular mechanisms by which tumor cell death impacts neighboring living tumor cells during various therapies, including chemotherapy, irradiation, and immune checkpoint blockade. NEP detection or targeting could offer new options for enhancing therapeutic efficacy. We anticipate that this study will stimulate intensive research and open discussions in this burgeoning field.