Project description:Dendritic cells (DCs) express high levels of PD-L1 in the tumor microenvironment and draining lymph nodes. Here, we explore the roles of PD-L1 signaling during immunogenic chemotherapy. DC-conditional PD-L1 knockout mice were inoculated with MC38-OVA tumors and treated with doxorubicin. T cells were isolated from draining lymph node for single cell RNA sequencing.
Project description:Dendritic cells (DCs) express high levels of PD-L1 in the tumor microenvironment. However, the physiological functions of PD-L1 on DCs remain incompletely understood. Here, we explored the roles of PD-L1 signaling in dendritic cells. PD-L1 was knocked out in DC2.4 cells and transcriptional profiles were analyzed.
Project description:Despite the remarkable success of programmed death 1/PD-L1 inhibition in tumor therapy, only a minority of patients benefits from it. Previous studies suggest the anti-PD-1 treatment failure may attribute to the intrinsic functions of PD-L1 in cancer cells. Here, we established a genome-wide CRISPR synthetic lethality screen to systematic explore the PD-L1 intrinsic function in head and neck squamous cell carcinoma (HNSCC) cells. Ferroptosis related genes were identified to be essential for PD-L1 deficient cell viability. Genetic and pharmacological induction of ferroptosis accelerated cell death in PD-L1 knockout cells. PD-L1 knockout cells were also highly susceptible to immunogenic ferroptosis in vitro and in vivo. Mechanistically, nuclear PD-L1 transcriptionally activated SOD2 expression to maintain redox homeostasis. Importantly, the lower ROS and ferroptosis were observed in HNSCC patients with the higher expression of PD-L1. In summary, our study illustrates that PD-L1 confers ferroptosis resistance by activating SOD2-meidated redox homeostasis in HNSCC cells, indicating an enhanced therapeutic effect can be achieved by targeting the intrinsic PD-L1 function during immunotherapy.
Project description:Despite the remarkable success of programmed death 1/PD-L1 inhibition in tumor therapy, only a minority of patients benefits from it. Previous studies suggest the anti-PD-1 treatment failure may attribute to the intrinsic functions of PD-L1 in cancer cells. Here, we established a genome-wide CRISPR synthetic lethality screen to systematic explore the PD-L1 intrinsic function in head and neck squamous cell carcinoma (HNSCC) cells. Ferroptosis related genes were identified to be essential for PD-L1 deficient cell viability. Genetic and pharmacological induction of ferroptosis accelerated cell death in PD-L1 knockout cells. PD-L1 knockout cells were also highly susceptible to immunogenic ferroptosis in vitro and in vivo. Mechanistically, nuclear PD-L1 transcriptionally activated SOD2 expression to maintain redox homeostasis. Importantly, the lower ROS and ferroptosis were observed in HNSCC patients with the higher expression of PD-L1. In summary, our study illustrates that PD-L1 confers ferroptosis resistance by activating SOD2-meidated redox homeostasis in HNSCC cells, indicating an enhanced therapeutic effect can be achieved by targeting the intrinsic PD-L1 function during immunotherapy.
Project description:Multiple myeloma (MM) is a malignant neoplasm originating in the plasma cell system, with a higher incidence in elderly individuals. While immune checkpoint blockade-based tumor immunotherapy has shown promising advancements in myeloma treatment, conventional chemotherapy remains the primary therapeutic modality. It remains unclear whether chemotherapy influences the expression of immune checkpoints in myeloma, thus impacting the therapeutic efficacy of checkpoint-related antibodies. In this study, we found that treatment of myeloma cells with chemotherapy drugs such as melphalan or bortezomib induces DNA damage and activates the cGAS/STING signaling pathway. This activation promotes the phosphorylation of the transcription factor IRF7, which then binds to the promoter region of SEI1 gene to enhance its transcription. The SEI1 protein directly interacts with the enhancer factors CBP/p300 and RNA polymerase II (pol II)-associated PAF1 complex, promoting transcriptional activity and leading to the upregulation of PD-L1 expression and causing immune escape in myeloma. These findings not only provide valuable insights for enhancing the therapeutic efficacy of chemotherapy in myeloma but also reveal a novel regulatory mechanism for PD-L1.
Project description:Despite centuries of research, metastatic cancer remains incurable due to resistance against all conventional cancer therapeutics. Alternative strategies leveraging non-proliferative vulnerabilities in cancer are required to overcome cancer recurrence. Ferroptosis is an iron dependent cell death pathway that has shown promising pre-clinical activity in several contexts of therapeutic resistant cancer. However, ferroptosis sensitivity is highly variable across tissue types and cell state posing a challenge for clinical translation. We describe a convergent phenotype induced by chemotherapy where cells surviving chemotherapy have similar transcriptomic signatures and dysregulated iron homeostasis, regardless of initial cell type or chemotherapy used. Elevated labile iron levels are counteracted by NRF2 signaling that does not alleviate the amount of labile iron. Selectively inhibiting GPX4 leads to uniform susceptibility to ferroptosis in surviving cells, highlighting the common reliance on lipid peroxidation defenses. Cellular iron dysregulation is a vulnerability of chemoresistant cancer cells that can be leveraged by triggering ferroptosis
Project description:Despite centuries of research, metastatic cancer remains incurable due to resistance against all conventional cancer therapeutics. Alternative strategies leveraging non-proliferative vulnerabilities in cancer are required to overcome cancer recurrence. Ferroptosis is an iron dependent cell death pathway that has shown promising pre-clinical activity in several contexts of therapeutic resistant cancer. However, ferroptosis sensitivity is highly variable across tissue types and cell state posing a challenge for clinical translation. We describe a convergent phenotype induced by chemotherapy where cells surviving chemotherapy have similar transcriptomic signatures and dysregulated iron homeostasis, regardless of initial cell type or chemotherapy used. Elevated labile iron levels are counteracted by NRF2 signaling that does not alleviate the amount of labile iron. Selectively inhibiting GPX4 leads to uniform susceptibility to ferroptosis in surviving cells, highlighting the common reliance on lipid peroxidation defenses. Cellular iron dysregulation is a vulnerability of chemoresistant cancer cells that can be leveraged by triggering ferroptosis
Project description:Blocking the PD-1/PD-L1 immunosuppressive pathway has shown promise in the treatment of certain cancers including melanoma. This study investigates differences in the gene expression profiles of human melanomas that do or do not display the immunosuppressive protein PD-L1. Further understanding of genes expressed within the tumor microenvironment of PD-L1+ tumors may lead to improved rationally designed treatments. Gene expression profiling was performed on total RNA extracted by laser capture microdissection from 11 archived formalin-fixed paraffin-embedded (FFPE) melanoma specimens, 5 of which were PD-L1 positive and 6 PD-L1 negative. Details of the design, and the gene signatures found are given in the paper associated with this GEO Series: Janis M. Taube, Geoffrey D. Young, Tracee L. McMiller, Shuming Chen, January T. Salas, Theresa S. Pritchard, Haiying Xu, Alan K. Meeker, Jinshui Fan, Chris Cheadle, Alan E. Berger, Drew M. Pardoll, and Suzanne L. Topalian, Differential expression of immune-regulatory genes associated with PD-L1 display in melanoma: implications for PD-1 pathway blockade, Clin Cancer Res 2015, in press.
Project description:BackgroundChemotherapy is currently evaluated in order to enhance the efficacy of immune checkpoint blockade (ICB) therapy in colorectal cancer. However, the mechanisms by which these drugs could synergize with ICB remains unclear. The impact of chemotherapy on the PD-1/PD-L1 pathway and the resulting anticancer immune responses was assessed in two mouse models of colorectal cancer and validated in tumor samples from metastatic colorectal cancer patients that received neoadjuvant treatment. We demonstrated that 5-Fluorouracil plus Oxaliplatin (Folfox) drove complete tumor cure in mice when combined to anti-PD-1 treatment, while each monotherapy failed. This synergistic effect relies on the ability of Folfox to induce tumor infiltration by activated PD-1+ CD8 T cells in a T-bet dependent manner. This effect was concomitantly associated to the expression of PD-L1 on tumor cells driven by IFN-γ secreted by PD-1+ CD8 T cells, indicating that Folfox triggers tumor adaptive immune resistance. Finally, we observed an induction of PD-L1 expression and high CD8 T cell infiltration in the tumor microenvironment of colorectal cancer patients treated by Folfox regimen. Our study delineates a molecular pathway involved in Folfox-induced adaptive immune resistance in colorectal cancer. The results strongly support the use of immune checkpoint blockade therapy in combination with chemotherapies like Folfox.