Project description:we found that a proportion of human and murine brain tumor-initiating cells (BTICs) expressed programmed cell death protein (PD-1) in situ and in culture. PD-1 signaling through NF B promotes BTIC proliferation.
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:PD-L1 Inhibitor Regulates the miR-33a-5p/PTEN Signaling Pathway and Can Be Targeted to Sensitize Glioblastomas to Radiation. Glioblastoma (GBM) is the most common and lethal brain tumor in adults. Ionizing radiation (IR) is a standard treatment for GBM patients and results in DNA damage. However, the clinical efficacy of IR is limited due to therapeutic resistance. The programmed death ligand 1 (PD-L1) blockade has a shown the potential to increase the efficacy of radiotherapy by inhibiting DNA damage and repair responses. The miR-33a-5p is an essential microRNA that promotes GBM growth and self-renewal. In this study, we investigated whether a PD-L1 inhibitor (a small molecule inhibitor) exerted radio-sensitive effects to impart an anti-tumor function in GBM cells by modulating miR-33a-5p. U87 MG cells and U251 cells were pretreated with PD-L1 inhibitor. The PD-L1 inhibitor-induced radio-sensitivity in these cells was assessed by assaying cellular apoptosis, clonogenic survival assays, and migration. TargetScan and luciferase assay showed that miR-33a-5p targeted the phosphatase and tensin homolog (PTEN) 3' untranslated region. The expression level of PTEN was measured by western blotting, and was also silenced using small interfering RNAs. The levels of DNA damage following radiation was measured by the presence of γ-H2AX foci, cell cycle, and the mRNA of the DNA damage-related genes, BRCA1, NBS1, RAD50, and MRE11. Our results demonstrated that the PD-L1 inhibitor significantly decreased the expression of the target gene, miR-33a-5p. In addition, pretreatment of U87 MG and U251 cells with the PD-L1 inhibitor increased radio-sensitivity, as indicated by increased apoptosis, while decreased survival and migration of GBM cells. Mir-33a-5p overexpression or silencing PTEN in U87 MG and U251 cells significantly attenuated PD-L1 radiosensitive effect. Additionally, PD-L1 inhibitor treatment suppressed the expression of the DNA damage response-related genes, BRCA1, NBS1, RAD50, and MRE11. Our results demonstrated a novel role for the PD-L1 inhibitor in inducing radio- sensitivity in GBM cells, where inhibiting miR-33a-5p, leading to PTEN activated, and inducing DNA damage was crucial for antitumor immunotherapies to treat GBM.
Project description:Transcriptome analysis was used to identify tumor-independent changes after treatment with mouse neutralizing PD-1 or PD-L1 antibodies.
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:Programmed death ligand-1 (PD-L1) is a well-known transmembrane protein, which antibodies present effective clinical therapy in multiple human cancers. However, the function of tumor cell-intrinsic PD-L1 and its related mechanism in breast cancer remains incompletely studied. Programmed death ligand 1 (PD-L1) on the membrane of tumor cells strengthens tumor immune escape. Tumor cell-intrinsic PD-L1 is also involved in tumorigenesis and development, but the mechanism in regulating PD-L1 expression remains incompletely studied. Here, we report a novel mechanism for PD-L1 that can be induced by hepatitis B X-interacting protein (HBXIP), an oncogenic transcriptional coactivator, promoting breast cancer growth. Overexpression of PD-L1 increases breast cancer proliferation in vitro and in vivo. Transcriptomic analysis also reveals that PD-L1 plays a critical role in cancer development. Furthermore, we find that the expression of PD-L1 is positively associated with HBXIP in breast cancer clinical tissues as well as in cell lines, PD-L1 and HBXIP expression have higher levels in tumor. Mechanistically, HBXIP predominantly stimulates the promoter activity of PD-L1 through coactivating transcription factor ETS2. Especially, HBXIP induced PD-L1 acetylation with the acetyltransferase p300 at lysine 270 (K270), enhancing PD-L1 protein stability. Functionally, depletion of HBXIP markedly attenuates PD-L1-induced breast tumor growth in vitro and in vivo. Moreover, aspirin decreased breast cancer growth via targeting PD-L1 and HBXIP. Taken together, our results extend a new mechanism of PD-L1 functions, expound non-immune effects of PD-L1 and imply broader uses for PD-L1 as a target in breast cancer therapy.