ABCA12-mediated ceramide efflux governs breast cancer stem cell function
Ontology highlight
ABSTRACT: Cancer stem cells (CSCs) drive tumor growth, metastasis, relapse, and chemoresistance. However, it’s unclear how lipid metabolism, especially sphingolipids metabolism, regulates CSCs and chemoresistance. In this study, we developed spontaneous tumor models expressing a Sox9-GFP transgenic reporter and demonstrated that cancer cells expressing high levels of SOX9 functioned as CSCs in both primary tumors and metastases. Transcriptomics analyses uncovered that SOX9high CSCs upregulate ABCA12 lipid transporter. Functionally, downregulation of ABCA12 impaired cancer stemness and chemoresistance of SOX9high cells. Through lipidomic analysis, we demonstrated that ABCA12 regulates SOX9 expression and cancer stemness by controlling ceramide abundance. Blocking ceramide hydrolysis using acid ceramidase inhibitor D-NMAPPD sensitized tumors to chemotherapy and prevented enrichment of SOX9high CSCs. These data suggest a potential strategy for targeting CSCs and overcoming chemoresistance. We further demonstrated that ceramide inhibits the YAP/TAZ signaling that is required for SOX9 expression in breast CSCs.
Project description:By using a small molecule compound library targeting epigenetic enzymes we have identified BRD9 enzyme for eliminating CSCs. Genomic and proteomic studies revealed that BRD9/BAF complex regulates expression of stemness factors and chemoresistance by cooperating with TGFβ/Activin-SMAD2/3 signalling pathway. Chemical inhibition and genetic loss of function of BDR9 blocks the self-renewal of CSCs, reduces CSC invasiveness and resensitizes PDAC CSCs to conventional therapies. Analyses of chromatin architecture showed that BRD9 regulates the 3D chromatin looping between promoters and enhancers of stemness genes and EMT regulators in CSCs. BRD9 inhibition abrogated tumour formation in mice and eliminated CSCs in tumours from pancreatic cancer patients. Collectively, we uncovered BRD9 enzyme as an attractive therapeutic target for re-sensitizing and eliminating CSCs in pancreatic cancer patients.
Project description:Widespread intraperitoneal metastases and chemoresistance render ovarian cancer the leading cause of gynecological malignancy–related deaths, wherein TGF-β signaling plays the pivotal role by promoting cancer stem cells (CSCs) activity. The activation mechanism and key protumorigeneic events downstream of TGF-β signaling remain incompletely understood. Here, we identify hypoxic tumor microenvironment as an initiator of TGF-β signaling to promote HIF-2α positive CSC-mediated chemoresistance in high-grade serous ovarian cancer (HGSOC). Mechanistically, deubiquitinase USP9X, as a TGF-β downstream effector, stabilizes HIF-2ɑ in a hydroxylation- and ubiquitylation-dependent manner, thus promoting stemness reprogramming. Hypoxia and TGF-β signals converge on USP9X-HIF-2ɑ axis via multi-level regulations, which in turn facilitates Smad/HIF responses. Clinically, USP9X expression correlates with TGF-β signatures, CSCs characteristics, EMT behaviors, and chemotherapy responsiveness, along with HIF-2ɑ. Antagonizing USP9X efficiently represses tumor formation, metastasis, CSCs occurrence, while increasing chemosensitivity in orthotopic tumors, patient derived xenograft (PDX), organoid, and chemoresistant cell models, in part via restricting TGF-β and hypoxia activities. This study deciphers the critical role of hypoxic niche in stimulating TGF-β signaling, and a downstream USP9X-HIF-2ɑ proteostatic regulatory axis in priming the HGSOC stemness, thereby provides novel targeting venues to counteract TGF-β signaling in CSCs and meliorate clinical chemoresistance.
Project description:The goal of this study was to identify changes in the transcriptome that occur following Abca12 gene deletion relative to Control islets
Project description:The goal of this study was to identify changes in the transcriptome that occur following Abca12 gene deletion relative to Control islets
Project description:The high mortality rate of metastasis colorectal cancer (CRC) is mainly due to chemotherapy resistance. Evidence implicates cancer stem cells (CSCs) play essential roles in chemoresistance. The deubiquitinating enzymes are vital regulators in both CSCs maintenance. Targeting deubiquitinase might be potential strategies to clear CSCs and overcome chemotherapy resistance. Here, we demonstrated that ubiquitin-specific peptidase 4 (USP4) is a key regulator of cancer stemness by stabilizing β-catenin and Twist1 proteins in CRC cells. Additionally, U4-I05, a novel natural small molecule that targets the enzyme activity of USP4 is characterized. U4-I05 binds to the catalytic domain of USP4 at nanomolar concentrations, resulting in the proteasome-mediated degradation of β-catenin and Twist1. Furthermore, U4-I05 attenuated CSC features and augmented sensitivity to oxaliplatin and 5-fluorouracil. In a genetically engineered CRC mouse model, U4-I05 inhibited tumor metastasis and prolonged survival. Overall, this study identifies U4-I05 as a USP4 inhibitor that has meaningful efficacy toward CRC.
Project description:We have investigated the proteome changes induced by SOX4 overexpression in HCT-116 cells using iTRAQ-based quantitative proteomics. Bioinformatics analysis revealed that HDAC1 could be one of the important regulators in cancer stem cells (CSCs) maintenance. We found that SOX4 transcriptionally regulates HDAC1 to support the stemness of cancer stem cells (CSCs). This work revealed a novel underlying mechanism, SOX4-HDAC1 axis, for stemness maintenance of human cancer.
Project description:The biology of Harlequin Ichthyosis (HI), a devastating skin disorder, caused by loss of function mutations in the gene ABCA12, is poorly understood and to date no satisfactory treatment has been developed. We sought to investigate pathomechanisms of Harlequin Ichthyosis which could lead to the identification of safe and effective treatments to improve patients' quality of life. RNA-Seq analysis using normal skin (n=5) and HI patient skin (n=4) were performed to define the effects of loss of ABCA12. Functional annotation clustering analysis showed changes in three common groups: epidermal differentiation, lipid metabolism and inflammation (innate immunity and IFNγ signalling). In HI patient skin, gene expression of STAT1, STAT3 and Interleukin 36 (IL-36) A and G cytokines was significantly upregulated compared to normal skin, whereas IL-37, an inhibitor of innate immunity, was downregulated. RNA-Seq and functional assays were performed to define the effects of loss of ABCA12, using an engineered CRISPR-Cas9 ABCA12 KO 3D model. Functional annotation clustering analysis showed changes in three common groups: epidermal differentiation, lipid metabolism and inflammation.
Project description:Ovarian cancer (OC) is the most lethal gynecological cancer due to its late diagnosis and, importantly, its high rate of chemoresistance. Hypoxia in solid tumors is an important source of chemoresistance that can determine poor patient prognosis. Such chemoresistance relies on the presence of cancer stem cells (CSCs), and hypoxia promotes their generation through transcriptional activation by HIF transcription factors. We use OC cell lines, xenograft models, OC patient samples, transcriptional databases, iPSCs and ATAC-seq. We show here that hypoxia induces the formation of ovarian CSCs through transcriptional activation of the PLD2 gene encoding phospholipase D2. HIF-1 activates PLD2 transcription through hypoxia response elements located within PLD2 promoter and an intronic enhancer. PLD2 overexpression leads to similar effects than hypoxia, increasing CSC-like features, stemness gene expression and enhancing cell reprogramming in OC cells, as well as chromatin accessibility around stemness genes detected by ATAC-seq. Conversely, PLD2 depletion in hypoxia partially suppresses these effects, indicating that PLD2 is a major determinant of hypoxia-induced CSC generation in OC. Indeed, PLD2 expression is high in OC patients leading to poor survival and a transcriptional switch in the genes related to the response to hypoxia and stemness. Finally, we demonstrate that PLD2 overexpression provokes resistance to platinum-based chemotherapy and that combination of cisplatin with pharmacological inhibition of PLD2 suppresses such resistance. Altogether, our work highlights the importance of the HIF-1-PLD2 axis for CSC generation and chemoresistance in OC and proposes an alternative treatment for patients with high PLD2 expression.
Project description:Post-treatment recurrence remains a major clinical challenge in colorectal cancer (CRC), and increasing evidence suggests that Cancer Stem Cells (CSCs) may mediate this process due to their enhanced resistance to conventional therapeutics. We hypothesized that the Pregnane-X receptor (PXR) may drive the chemoresistance of colorectal CSCs.. shRNA-mediated PXR down-regulation was used to analyze the role of PXR on self-renewal in the colorectal cancer cell Line LS174T. Expression and activity of PXR were quantified under conditions that promote Cancer Stem Cells (CSCs) enrichment. Conversely, CSC characterization was performed in cells enriched along their PXR activity level.