Identification of genes bound by NFAT5-SMADs complex
Ontology highlight
ABSTRACT: Oncogenic KRAS is now considered a druggable target; however, multiple mechanisms contribute to the development of resistance to KRAS-targeted therapy. A significant factor in therapy resistance is the alteration in cell state or cellular plasticity, exemplified by the epithelial-to-mesenchymal transition (EMT) phenotype. In pancreatic ductal adenocarcinoma (PDAC), the negative correlation between addiction to oncogenic KRAS signaling and EMT has been observed, yet the role of cell plasticity and its underlying mechanisms in governing resistance remain unclear. Our findings reveal that the pivotal EMT driver, TGFβ, facilitates KRAS bypass in PDAC through the nuclear factor NFAT5. NFAT5 interacts with canonical TGFβ factors SMAD3 and SMAD4, inducing EMT and therapy resistance. To identify DNA bound by the NFAT5-SMADs complex, we conducted Chromatin IP followed by next-generation sequencing (ChIP-seq) using antibodies binding to NFAT5, SMAD2, SMAD3, and SMAD4.
Project description:Oncogenic KRAS is now considered a druggable target; however, multiple mechanisms contribute to the development of resistance to KRAS-targeted therapy. A significant factor in therapy resistance is the alteration in cell state or cellular plasticity, exemplified by the epithelial-to-mesenchymal transition (EMT) phenotype. In pancreatic ductal adenocarcinoma (PDAC), the negative correlation between addiction to oncogenic KRAS signaling and EMT has been observed, yet the role of cell plasticity and its underlying mechanisms in governing resistance remain unclear. Our findings reveal that the pivotal EMT driver, TGFβ, facilitates KRAS bypass in PDAC through the nuclear factor NFAT5. NFAT5 interacts with canonical TGFβ factors SMAD3 and SMAD4, inducing EMT and therapy resistance. To unravel the regulatory role of the NFAT5-SMADs complex in KRAS* bypass, we conducted transcriptomic analysis in TGFβ-treated, KRAS*-depleted iKPC spheroids.
Project description:Transforming growth factor beta (TGFβ) superfamily signaling is a prime inducer of epithelial-mesenchymal transitions (EMT) that foster cancer cell invasion and metastasis, a major cause of cancer-related deaths. Yet, TGFβ signaling is frequently inactivated in human tumor entities including colorectal cancer (CRC) and pancreatic adenocarcinoma (PAAD) with a high proportion of mutations incapacitating SMAD4, which codes for a transcription factor (TF) central to canonical TGFβ and bone morphogenetic protein (BMP) signaling. Beyond its role in initiating EMT, SMAD4 was reported to crucially contribute to subsequent gene regulatory events during EMT execution. It is therefore widely assumed that SMAD4-mutant (SMAD4mut) cancer cells are unable to undergo EMT. Here, we scrutinized this notion and probed for potential SMAD4-independent EMT execution using SMAD4mut CRC cell lines. We show that SMAD4mut cells exhibit morphological changes, become invasive, and regulate EMT marker genes upon induction of the EMT-TF SNAIL1. Furthermore, SNAIL1-induced EMT in SMAD4mut cells was found to be entirely independent of TGFβ/BMP receptor activity. Global assessment of the SNAIL1‑dependent transcriptome confirmed the manifestation of an EMT gene regulatory program in SMAD4mut cells highly related to established EMT signatures. Finally, analyses of human tumor transcriptomes showed that SMAD4 mutations are not underrepresented in mesenchymal tumor samples and that expression patterns of EMT‑associated genes are similar in SMAD4mut and SMAD4 wild-type cases. Altogether, our findings reveal considerable plasticity of gene regulatory networks operating in EMT execution and establish that EMT is not categorically precluded in SMAD4mut tumors, which is relevant for their diagnostic and therapeutic evaluation. To identify genes regulated during EMT execution in HT29 cells, two clonal HT29 cell populations (4F5 and 3C2) overexpressing Snail1-HA in a doxycycline (Dox)-inducible manner, as well as control cells were treated with Dox for different periods of time.
Project description:TGFβ is known to be a potent inducer of EMT, a process involved in tumor invasion. TIF1γ has been reported to participate to TGFβ signaling. In order to understand the role of TIF1γ in TGFβ signaling and its requirement for EMT, we analyzed the TGFβ1 response of human mammary epithelial cell lines. A strong EMT increase was observed in TIF1γ-silenced cells after TGFβ1 treatment, whereas Smad4 inactivation completely blocked this process. In support of these observations, microarray data show that the functions of several TIF1γ target genes can be linked to EMT. As a negative regulator of Smad4, TIF1γ could be critical for the regulation of TGFβ signaling. This work highlights the molecular relationship between TIF1γ and Smad4 in TGFβ1 signaling and EMT. Total mRNA extractions were performed for 11 samples from transfected HMEC-TR. Replicates are rimo1, 6; rimo3, 9; rimo2, 7; rimo 4, 10 and rimo 5, 11. Rimo 8 is a single experiment. All RNA extractions were obtained from two independent cell cultures excepted for rimo8. Rimo 1, 6 are replicate for ctrl-; Rimo 3, 9 are replicate for ctrl+; Rimo 2, 7 are replicate for SiTIF-; Rimo 4, 10 are replicate for SiTIF+; Rimo8 is SiSmad4-; and Rimo5, 11 are replicate for SiSmad4+. ctrl means that HMEC-TR were transfected with an SiRNA scramble. "siSmad4" means that HMEC-TR were transfected with an SiRNA anti Smad4. "siTIF" means that HMEC-TR were transfected with an SiRNA anti TIF1γ. "-" means that cells were grown without TGFβ. "+" means that cells were treated with 5 ng/ml TGFβ1 for 24h.
Project description:TGFβ is known to be a potent inducer of EMT, a process involved in tumor invasion. TIF1γ has been reported to participate to TGFβ signaling. In order to understand the role of TIF1γ in TGFβ signaling and its requirement for EMT, we analyzed the TGFβ1 response of human mammary epithelial cell lines. A strong EMT increase was observed in TIF1γ-silenced cells after TGFβ1 treatment, whereas Smad4 inactivation completely blocked this process. In support of these observations, microarray data show that the functions of several TIF1γ target genes can be linked to EMT. As a negative regulator of Smad4, TIF1γ could be critical for the regulation of TGFβ signaling. This work highlights the molecular relationship between TIF1γ and Smad4 in TGFβ1 signaling and EMT.
Project description:Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest and most metastatic cancers in human. PDACs respond poorly to therapies, partly due to cancer stem cells (CSCs) that self-renew, survive chemotherapies, metastasise and replenish the tumour. Factors secreted by tumour cells mediate autocrine/paracrine crosstalk with surrounding cells contributing to the stem cell niche but are still insufficiently characterised. Here we used quantitative SILAC proteomics to identify secreted factors enriched in CSC secretome compared to non-CSCs. Among them were GDF15 and VGF, factors involved in cachexia and pain stimuli. GDF15 and VGF promoted CSC self-renewal and growth through autocrine effects. TGFβ/Activin signalling lowered GDF15 and VGF expression via SMAD2/3-SMAD4-SNON, switching to ATF4-CREB-mediated induction upon cell stress. Co-culture of PDAC-CSCs and hESC-derived neural cells for mimicking cellular crosstalk in PDAC revealed that paracrine signalling via GDF15/VGF promoted nociceptor formation and neurite outgrowth. In turn, Substance P from neurons supported CSC self-renewal, EMT/migration and clonal evolution that was also impacted by SMAD4 genetic status. Lastly, the serum levels of GDF15 and VGF were elevated in PDAC patients suggesting their utility as biomarkers for PDAC detection. Collectively, our data uncovered that cachexia and pain signalling factors mediate the crosstalk between CSCs and nociceptors.
Project description:Endoplasmic reticulum to mitochondria Ca2+ transfer is important for cancer cell survival, but the role of mitochondrial Ca2+ uptake through the mitochondrial Ca2+ uniporter (MCU) in pancreatic adenocarcinoma (PDAC) is poorly understood. Here, we show that increased MCU expression is associated with malignancy and poorer outcomes in PDAC patients. In isogenic murine PDAC models, Mcu deletion (McuKO) ablated mitochondrial Ca2+ uptake, which reduced proliferation and inhibited self-renewal. Orthotopic implantation of MCU-null tumor cells reduced primary tumor growth and metastasis. Mcu deletion reduced the cellular plasticity of tumor cells by inhibiting epithelial-to- mesenchymal transition (EMT), which contributes to metastatic competency in PDAC. Mechanistically, the loss of mitochondrial Ca2+ uptake reduced expression of the key EMT transcription factor Snail and secretion of the EMT-inducing ligand TGFβ. Snail re-expression and TGFβ treatment rescued deficits in McuKO cells and restored their metastatic ability. Thus, MCU may present a therapeutic target in PDAC to limit cancer-cell-induced EMT and metastasis.
Project description:The transforming growth factor beta (TGFβ) related signaling is one of the most important signaling pathways regulating early developmental events. Smad2 and Smad3 are structurally similar and it is mostly considered that they are equally important in mediating TGFβ signals. Here, we show that Smad3 is an insensitive TGFβ transducer as compared with Smad2. Smad3 preferentially localizes within the nucleus and is thus sequestered from membrane signaling. The ability of Smad3 in oligomerization with Smad4 upon agonist stimulation is also impaired given its unique linker region. Smad2 mediated TGFβ signaling plays a crucial role in epiblast development and patterning of three germ layers. However, signaling unrelated nuclear localized Smad3 is dispensable for TGFβ signaling-mediated epiblast specification, but important for early neural development, an event blocked by TGFβ/Smad2 signaling. Both Smad2 and Smad3 bind to the conserved Smads binding element (SBE), but they show nonoverlapped target gene binding specificity. We conclude that Smad2 and Smad3 possess differential sensitivities in relaying TGFβ signaling and have distinct roles in regulating early developmental events.
Project description:TGFβ signaling induces several cell phenotypes including cellular senescence, a stable form of cell cycle arrest accompanied by a secretory program, and epithelial-mesenchymal transition (EMT) in normal epithelial cells. During carcinogenesis cells lose the ability to undergo senescence in response to TGFβ but they maintain an EMT, which can contribute to tumor progression and resistance. A screen with active kinases in HMECs upon TGFβ treatment identified that the serine threonine kinase RSK3, or RPS6KA2, reverted TGFβ-induced senescence. Interestingly, RSK3 expression decreased in response to TGFβ in a SMAD3-dependent manner, and its constitutive expression rescued SMAD3-induced premature senescence, indicating that decrease of RSK3 itself contributes to TGFβ-induced senescence. Mechanistically, using transcriptomic analyses and affinity purification coupled to mass spectrometry-based proteomics, we unveiled that RSK3 regulates senescence by inhibiting NF-κΒ pathway through the decrease in proteasome-mediated IκBα degradation. Strikingly, senescent TGFβ-treated HMEC display features of epithelial to mesenchymal transition (EMT) and during RSK3-induced senescence escape HMEC conserve EMT features. Importantly, RSK3 expression correlates with EMT and invasion, and anti-correlates with senescence and NF-κΒ in human claudin-low breast tumors and its expression accelerates formation of breast invasive tumors in the mouse mammary gland. We conclude that RSK3 switches cell fate from senescence to malignancy in response to TGFβ signals.
Project description:New and effective therapeutics are urgently needed for the treatment of pancreatic ductal adenocarcinoma (PDAC). The eIF4A/DDX2 RNA helicase drives translation of mRNAs with highly structured 5’UTRs. The natural compound silvestrol and synthetic analogues are potent and selective inhibitors of eIF4A1/2 that show promising activity in models of hematological malignancies. Here, we show silvestrol analogues have nanomolar activity against PDAC cell lines and organoids in vitro. Moreover, we see single agent activity in the KRAS/p53 mouse PDAC model and also against PDAC xenografts and primary, patient derived PDAC tumors. These therapeutic effects occur at non-toxic dose levels. Transcriptome-wide ribosome profiling, analyses of protein and gene expression, and translation reporter studies reveal that eIF4A inhibitors block an oncogenic translation program in PDAC cells that includes G-quadruplex containing mRNAs such as KRAS, MYC, YAP1, MET, SMAD3, TGFβ and others. Together, our data indicate that pharmacological inhibition of eIF4A disrupts oncoprotein production and shows efficacy across several PDAC models.