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: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:Programmed cell death 1 ligand 1 (PD-L1) is known to suppress immune system and to be an unfavorable prognostic factor in ovarian cancer. The purpose of this study was to elucidate the function of PD-L1 in peritoneal dissemination. Tumor cell lysis by CTLs was attenuated when PD-L1 on tumor cells was overexpressed and promoted when it was silenced. PD-L1 overexpression also inhibited gathering and degranulation of CTLs. Gene expression profile of mouse CTLs caused by PD-L1-overexpressing ovarian cancer was related to human CTLs exhaustion. In mouse ovarian cancer dissemination models, depleting PD-L1 expression on tumor cells resulted in inhibited tumor growth in the peritoneal cavity and prolonged survival. Restoring immune function by inhibiting immune-suppressive factors such as PD-L1 may be a promising therapeutic strategy for peritoneal dissemination. Genome-wide transcriptional changes in OT-1 mouse CD8+ T cells that were co-incubated with OVA peptide-loaded ID8 mouse ovarian cancer cell lines. CTLs from 4 mice were devided into 2 groups, and co-incubated with PD-L1-overexpressed ID8 or PD-L1-depleted ID8.
Project description:To identify which E3 ligases ubiquitinate PD-L1, we overexpressed PD-L1-Flag in HEK293 cells and used anti-Flag magnetic beads to pull down PD-L1 from cell lysates. The interacting proteins were then analyzed by mass spectrometry, revealing that three E3 ligases interact with PD-L1.