Epithelial-mesenchymal transition (EMT) is an important process triggered during cancer metastasis. Regulation of EMT is mostly initiated by outside signalling, including TGF-β, growth factors, Notch ...ligand, Wnt, and hypoxia. Many signalling pathways have been delineated to explain the molecular mechanisms of EMT. In this review, we will focus on the epigenetic regulation of two critical EMT signalling pathways: hypoxia and TGF-β. For hypoxia, hypoxia-induced EMT is mediated by the interplay between chromatin modifiers histone deacetylase 3 (HDAC3) and WDR5 coupled with the presence of histone 3 lysine 4 acetylation (H3K4Ac) mark that labels the promoter regions of various traditional EMT marker genes (e.g. CDH1, VIM). Recently identified new hypoxia-induced EMT markers belong to transcription factors (e.g. SMO, GLI1) that mediate EMT themselves. For TGF-β-induced ΕΜΤ, global chromatin changes, removal of a histone variant (H2A.Z), and new chromatin modifiers (e.g. UTX, Rad21, PRMT5, RbBP5, etc) are identified to be crucial for the regulation of both EMT transcription factors (EMT-TFs) and EMT markers (EMT-Ms). The epigenetic mechanisms utilized in these two pathways may serve as good model systems for other signalling pathways and also provide new potential therapeutic targets.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Cancer stemness represents one of the major mechanisms that predispose patients to tumor aggressiveness, metastasis, and treatment resistance. MicroRNA biogenesis is an important process controlling ...miRNA processing and maturation. Deregulation of miRNA biogenesis can lead to tumorigenesis and cancer stemness. DDX17 is a co-factor of the miRNA microprocessor. Misregulation of DDX17 can be associated with cancer stemness. K63-linked polyubiquitination of DDX17 presents a concerted mechanism of decreased synthesis of stemness-inhibiting miRNAs and increased transcriptional activation of stemness-related gene expression. K63-linked polyubiquitination of HAUSP serves as a scaffold to anchor HIF-1α, CBP, the mediator complex, and the super-elongation complex to enhance HIF-1α-induced gene transcription. Recent progress in RNA modifications shows that RNA N6-methyladenosine (m6A) modification is a crucial mechanism to regulate RNA levels. M6A modification of miRNAs can also be linked to tumorigenesis and cancer stemness. Overall, miRNA biogenesis and K63-linked polyubiquitination of DDX17 play an important role in the induction of cancer stemness. Delineation of the mechanisms and identification of suitable targets may provide new therapeutic options for treatment-resistant cancers.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Hypoxia is an important microenvironmental factor that induces cancer metastasis. Hypoxia/hypoxia-inducible factor-1α (HIF-1α) regulates many important steps of the metastatic processes, especially ...epithelial-mesenchymal transition (EMT) that is one of the crucial mechanisms to cause early stage of tumor metastasis. To have a better understanding of the mechanism of hypoxia-regulated metastasis, various hypoxia/HIF-1α-regulated target genes are categorized into different classes including transcription factors, histone modifiers, enzymes, receptors, kinases, small GTPases, transporters, adhesion molecules, surface molecules, membrane proteins, and microRNAs. Different roles of these target genes are described with regards to their relationship to hypoxia-induced metastasis. We hope that this review will provide a framework for further exploration of hypoxia/HIF-1α-regulated target genes and a comprehensive view of the metastatic picture induced by hypoxia.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This study investigated the pattern of recurrence of lung adenocarcinoma and the predictive value of histologic classification in resected lung adenocarcinoma using the new International Association ...for the Study of Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) classification system.
Histologic classification of 573 patients undergoing resection for lung adenocarcinoma was determined according to the IASLC/ATS/ERS classification system, and the percentage of each histologic component (lepidic, acinar, papillary, micropapillary, and solid) was recorded. The pattern of recurrence of those components and their predictive value were investigated.
The predominant histologic pattern was significantly associated with sex (P < .01), invasive tumor size (P < .01), T status (P < .01), N status (P < .01), TNM stage (P < .01), and visceral pleural invasion (P < .01). The percentage of recurrence was significantly higher in micropapillary- and solid-predominant adenocarcinomas (P < .01). Micropapillary- and solid-predominant adenocarcinomas had a significantly higher possibility of developing initial extrathoracic-only recurrence than other types (P < .01). The predominant pattern group (micropapillary or solid v lepidic, acinar, or papillary) was a significant prognostic factor in overall survival (OS; P < .01), probability of freedom from recurrence (P < .01), and disease-specific survival (P < .01) in multivariable analysis. For patients receiving adjuvant chemotherapy, solid-predominant adenocarcinoma was a significant predictor for poor OS (P = .04).
In lung adenocarcinoma, the IASLC/ATS/ERS classification system has significant prognostic and predictive value regarding death and recurrence. Solid-predominant adenocarcinoma was also a significant predictor in patients undergoing adjuvant chemotherapy. Prognostic and predictive information is important for stratifying patients for aggressive adjuvant chemoradiotherapy.
OBJECTIVE:This study investigated the prognostic value of the new International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society (IASLC/ATS/ERS) ...lung adenocarcinoma classification in resected stage I lung adenocarcinoma.
METHODS:Histological classification of 283 patients undergoing surgical resection for stage I lung adenocarcinoma was determined according to the IASLC/ATS/ERS classification after comprehensive histological subtyping with recording of the percentage of each histological component (lepidic, acinar, papillary, micropapillary, and solid) in 5% increments. Their impact on overall survival, recurrence, and postrecurrence survival was investigated.
RESULTS:The 5-year overall survival and recurrence-free rates were 81.6% and 76.9%, respectively. During follow-up, 57 (20.1%) patients developed recurrence. The 2-year postrecurrence survival rate was 72.3%. The solid predominant group is associated with significant more male sex, higher smoking exposure, larger tumor size, and more poorly differentiated histological grade. Lepidic predominant group had significantly better overall survival (P = 0.002). Micropapillary and solid predominant groups had significantly lower probability of freedom from recurrence (P = 0.004). Older age (P = 0.039), visceral pleural invasion to the surface (PL2) (P = 0.009), and high grade (micropapillary/solid predominant) of the new classification (P = 0.028) were predictors of recurrence in multivariate analysis. The solid predominant group tends to have significantly worse postrecurrence survival (P = 0.074).
CONCLUSIONS:The new adenocarcinoma classification has significant impact on death and recurrence in stage I lung adenocarcinoma. Patients with PL2 and micropapillary/solid predominant pattern have significant higher risk for recurrence. This information is important for patient stratification for aggressive adjuvant chemoradiation therapy.
Hypoxia is a microenvironmental factor which plays a critical role in development and tumor progression. The hypoxic response is mainly mediated by hypoxia inducible factor-1 (HIF-1) composed of ...HIF-1alpha and HIF-1beta, which becomes active under low oxygen condition. HIF-1 activates the transcription of hypoxia inducible genes which regulate diverse cellular functions including metabolism, angiogenesis, and invasion. In cancer metastasis, HIF-1-regulated genes promote angiogenesis, invasion, and epithelial-mesenchymal transition (EMT), a critical step of metastasis. TWIST is a master regulator of gastrulation and mesoderm specification and is recently implicated to be essential to mediate cancer metastasis. We recently showed that HIF-1 promotes EMT through direct regulation of TWIST expression. TWIST is critical for hypoxia mediated EMT and metastasis. TWIST plays a non-redundant role in relation to other EMT regulators (e.g. Snail) under hypoxia. Co-expression of HIF-1alpha, TWIST and Snail could be used as a prognostic marker in cancer patients. These findings suggest that hypoxia and/or HIF-1 orchestrates EMT and metastasis through the coordinated regulation of different EMT regulators. Our results provide the important link between hypoxia and developmental processes regulated by TWIST. The implications of the roles of hypoxia and TWIST in early embryonic development are discussed.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
Ubiquitination modulates a large repertoire of cellular functions and thus, dysregulation of the ubiquitin system results in multiple human diseases, including cancer. Ubiquitination requires an E3 ...ligase, which is responsible for substrate recognition and conferring specificity to ubiquitination. HUWE1 is a multifaceted HECT domain-containing ubiquitin E3 ligase, which catalyzes both mono-ubiquitination and K6-, K48- and K63-linked poly-ubiquitination of its substrates. Many of the substrates of HUWE1 play a crucial role in maintaining the homeostasis of cellular development. Not surprisingly, dysregulation of HUWE1 is associated with tumorigenesis and metastasis. HUWE1 is frequently overexpressed in solid tumors, but can be downregulated in brain tumors, suggesting that HUWE1 may possess differing cell-specific functions depending on the downstream targets of HUWE1. This review introduces some important discoveries of the HUWE1 substrates, including those controlling proliferation and differentiation, apoptosis, DNA repair, and responses to stress. In addition, we review the signaling pathways HUWE1 participates in and obstacles to the identification of HUWE1 substrates. We also discuss up-to-date potential therapeutic designs using small molecules or ubiquitin variants (UbV) against the HUWE1 activity. These molecular advances provide a translational platform for future bench-to-bed studies. HUWE1 is a critical ubiquitination modulator during the tumor progression and may serve as a possible therapeutic target for cancer treatment.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Mammalian cells constantly encounter hypoxia, which is a stress condition occurring during development and physiological processes. To adapt to this inevitable condition, cells develop various ...mechanisms to cope with this stress and survive. In addition to the activation/stabilization of transcriptional regulators (hypoxia‐inducible factors), other epigenetic mechanisms of gene regulation are used. These mechanisms are mediated by various players including transcriptional coregulators, chromatin‐modifying complexes, histone modification enzymes and changes in DNA methylation status. Recent progress in all the fields mentioned above has greatly improved the knowledge of how gene regulation contributes to the hypoxic response. This review should shed light on the molecular epigenetic mechanisms of hypoxia‐induced gene regulation and help understand the processes adapted by cells to cope with hypoxia.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Intratumoural hypoxia induces HIF-1α and promotes tumour progression, metastasis and treatment resistance. HIF-1α stability is regulated by VHL-E3 ligase-mediated ubiquitin-dependent degradation; ...however, the hypoxia-regulated deubiquitinase that stabilizes HIF-1α has not been identified. Here we report that HAUSP (USP7) deubiquitinase deubiquitinates HIF-1α to increase its stability, induce epithelial-mesenchymal transition and promote metastasis. Hypoxia induces K63-linked polyubiquitinated HAUSP at lysine 443 to enhance its functions. Knockdown of HAUSP decreases acetylation of histone 3 lysine 56 (H3K56Ac). K63-polyubiquitinated HAUSP interacts with a ubiquitin receptor CBP to specifically mediate H3K56 acetylation. ChIP-seq analysis of HAUSP and HIF-1α binding reveals two motifs responsive to hypoxia. HectH9 is the E3 ligase for HAUSP and a prognostic marker together with HIF-1α. This report demonstrates that hypoxia-induced K63-polyubiquitinated HAUSP deubiquitinates HIF-1α and causes CBP-mediated H3K56 acetylation on HIF-1α target gene promoters to promote EMT/metastasis, further defining HAUSP as a therapeutic target in hypoxia-induced tumour progression.
Markers of cancer stemness predispose patients to tumor aggressiveness, drug and immunotherapy resistance, relapse, and metastasis. DDX17 is a cofactor of the Drosha-DGCR8 complex in miRNA biogenesis ...and transcriptional coactivator and has been associated with cancer stem-like properties. However, the precise mechanism by which DDX17 controls cancer stem-like features remains elusive. Here, we show that the E3 ligase HectH9 mediated K63-polyubiquitination of DDX17 under hypoxia to control stem-like properties and tumor-initiating capabilities. Polyubiquitinated DDX17 disassociated from the Drosha-DGCR8 complex, leading to decreased biogenesis of anti-stemness miRNAs. Increased association of polyubiquitinated DDX17 with p300-YAP resulted in histone 3 lysine 56 (H3K56) acetylation proximal to stemness-related genes and their subsequent transcriptional activation. High expression of HectH9 and six stemness-related genes (
, and
) predicted poor survival in patients with head and neck squamous cell carcinoma and lung adenocarcinoma. Our findings demonstrate that concerted regulation of miRNA biogenesis and histone modifications through posttranslational modification of DDX17 underlies many cancer stem-like features. Inhibition of DDX17 ubiquitination may serve as a new therapeutic venue for cancer treatment. SIGNIFICANCE: Hypoxia-induced polyubiquitination of DDX17 controls its dissociation from the pri-miRNA-Drosha-DCGR8 complex to reduce anti-stemness miRNA biogenesis and association with YAP and p300 to enhance transcription of stemness-related genes.
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