5 research outputs found
CRISPR-Mediated Reactivation of DKK3 Expression Attenuates TGF-β Signaling in Prostate Cancer
The DKK3 gene encodes a secreted protein, Dkk-3, that inhibits prostate tumor growth and
metastasis. DKK3 is downregulated by promoter methylation in many types of cancer, including
prostate cancer. Gene silencing studies have shown that Dkk-3 maintains normal prostate epithelial
cell homeostasis by limiting TGF-β/Smad signaling. While ectopic expression of Dkk-3 leads to
prostate cancer cell apoptosis, it is unclear if Dkk-3 has a physiological role in cancer cells. Here,
we show that treatment of PC3 prostate cancer cells with the DNA methyltransferase (DNMT)
inhibitor decitabine demethylates the DKK3 promoter, induces DKK3 expression, and inhibits
TGF-β/Smad-dependent transcriptional activity. Direct induction of DKK3 expression using
CRISPR-dCas9-VPR also inhibited TGF-β/Smad-dependent transcription and attenuated PC3 cell
migration and proliferation. These effects were not observed in C4-2B cells, which do not respond to
TGF-β. TGF-β signals can regulate gene expression directly via SMAD proteins and indirectly by
increasing DNMT expression, leading to promoter methylation. Analysis of genes downregulated by
promoter methylation and predicted to be regulated by TGF-β found that DKK3 induction increased
expression of PTGS2, which encodes cyclooxygenase-2. Together, these observations provide support
for using CRISPR-mediated induction of DKK3 as a potential therapeutic approach for prostate
cancer and highlight complexities in Dkk-3 regulation of TGF-β signaling
Clearance of senescent macrophages ameliorates tumorigenesis in KRAS-driven lung cancer
The accumulation of senescent cells in the tumor microenvironment can drive tumorigenesis in a paracrine manner through the senescence-associated secretory phenotype (SASP). Using a new p16-FDR mouse line, we show that macrophages and endothelial cells are the predominant senescent cell types in murine KRAS-driven lung tumors. Through single cell transcriptomics, we identify a population of tumor-associated macrophages that express a unique array of pro-tumorigenic SASP factors and surface proteins and are also present in normal aged lungs. Genetic or senolytic ablation of senescent cells, or macrophage depletion, result in a significant decrease in tumor burden and increased survival in KRAS-driven lung cancer models. Moreover, we reveal the presence of macrophages with senescent features in human lung pre-malignant lesions, but not in adenocarcinomas. Taken together, our results have uncovered the important role of senescent macrophages in the initiation and progression of lung cancer, highlighting potential therapeutic avenues and cancer preventative strategies
CRISPR-Mediated Reactivation of DKK3 Expression Attenuates TGF-β Signaling in Prostate Cancer
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Clearance of senescent macrophages ameliorates tumorigenesis in KRAS-driven lung cancer.
The accumulation of senescent cells in the tumor microenvironment can drive tumorigenesis in a paracrine manner through the senescence-associated secretory phenotype (SASP). Using a new p16-FDR mouse line, we show that macrophages and endothelial cells are the predominant senescent cell types in murine KRAS-driven lung tumors. Through single cell transcriptomics, we identify a population of tumor-associated macrophages that express a unique array of pro-tumorigenic SASP factors and surface proteins and are also present in normal aged lungs. Genetic or senolytic ablation of senescent cells, or macrophage depletion, result in a significant decrease in tumor burden and increased survival in KRAS-driven lung cancer models. Moreover, we reveal the presence of macrophages with senescent features in human lung pre-malignant lesions, but not in adenocarcinomas. Taken together, our results have uncovered the important role of senescent macrophages in the initiation and progression of lung cancer, highlighting potential therapeutic avenues and cancer preventative strategies
Metastatic-niche labelling reveals parenchymal cells with stem features.
Direct investigation of the early cellular changes induced by metastatic cells within the surrounding tissue remains a challenge. Here we present a system in which metastatic cancer cells release a cell-penetrating fluorescent protein, which is taken up by neighbouring cells and enables spatial identification of the local metastatic cellular environment. Using this system, tissue cells with low representation in the metastatic niche can be identified and characterized within the bulk tissue. To highlight its potential, we applied this strategy to study the cellular environment of metastatic breast cancer cells in the lung. We report the presence of cancer-associated parenchymal cells, which exhibit stem-cell-like features, expression of lung progenitor markers, multi-lineage differentiation potential and self-renewal activity. In ex vivo assays, lung epithelial cells acquire a cancer-associated parenchymal-cell-like phenotype when co-cultured with cancer cells and support their growth. These results highlight the potential of this method as a platform for new discoveries.This work was supported by the Francis Crick Institute which receives its core funding from Cancer Research UK (FC001112), the UK Medical Research Council (FC001112), and the Wellcome Trust (FC001112) and the European Research Council grant (ERC CoG-H2020-725492); and by the Wellcome Trust â MRC Stem Cell Institute which receives funding from the Sir Henry Dale Fellowship from Wellcome and the Royal Society (107633/Z/15/Z) and the European Research Council Starting Grant (679411)