Nuclear E-Cadherin Acetylation Promotes Colorectal Tumorigenesis via Enhancing β-Catenin Activity

Implication of protein post translational modifications in gastric cancer

Gastric cancer (GC) is one of the most common and highly lethal malignant tumors worldwide, and its occurrence and development are regulated by multiple molecular mechanisms. Post-translational modifications (PTM) common forms include ubiquitylation, phosphorylation, acetylation and methylation. Emerging research has highlighted lactylation and glycosylation. The diverse realm of PTM and PTM crosstalk is linked to many critical signaling events involved in neoplastic transformation, carcinogenesis and metastasis. This review provides a comprehensive overview of the impact of PTM on the occurrence and progression of GC. Specifically, aberrant PTM have been shown to alter the proliferation, migration, and invasion capabilities of GC cells. Moreover, PTM are closely associated with resistance to chemotherapeutic agents in GC. Notably, this review also discusses the phenomenon of PTM crosstalk, highlighting the interactions among PTM and their roles in regulating signaling pathways and protein functions. Therefore, in-depth investigation into the mechanisms of PTM and the development of targeted therapeutic strategies hold promise for advancing early diagnosis, treatment, and prognostic evaluation of GC, offering novel insights and future research directions.

The role of acetylation and deacetylation in cancer metabolism

As a hallmark of cancer, metabolic reprogramming adjusts macromolecular synthesis, energy metabolism and redox homeostasis processes to adapt to and promote the complex biological processes of abnormal growth and proliferation. The complexity of metabolic reprogramming lies in its precise regulation by multiple levels and factors, including the interplay of multiple signalling pathways, precise regulation of transcription factors and dynamic adjustments in metabolic enzyme activity. In this complex regulatory network, acetylation and deacetylation, which are important post-translational modifications, regulate key molecules and processes related to metabolic reprogramming by affecting protein function and stability. Dysregulation of acetylation and deacetylation may alter cancer cell metabolic patterns by affecting signalling pathways, transcription factors and metabolic enzyme activity related to metabolic reprogramming, increasing the susceptibility to rapid proliferation and survival. In this review, we focus on discussing how acetylation and deacetylation regulate cancer metabolism, thereby highlighting the central role of these post-translational modifications in metabolic reprogramming, and hoping to provide strong support for the development of novel cancer treatment strategies. KEY POINTS: Protein acetylation and deacetylation are key regulators of metabolic reprogramming in tumour cells. These modifications influence signalling pathways critical for tumour metabolism. They modulate the activity of transcription factors that drive gene expression changes. Metabolic enzymes are also affected, altering cellular metabolism to support tumour growth.

Banxia Xiexin Decoction delays colitis-to-cancer transition by inhibiting E-cadherin/β-catenin pathway via Fusobacterium nucleatum FadA

ETHNOPHARMACOLOGICAL RELEVANCE

Colitis is an important risk factor for the occurrence of colorectal cancer (CRC), and the colonization of Fusobacterium nucleatum (Fn) in the intestines accelerates this transformation process. Banxia Xiexin Decoction (BXD), originating from Shanghanlun, is a classic prescription for treating gastrointestinal diseases. Current researches indicate that BXD can effectively delay the colitis-to-cancer transition, but it is still unclear whether it can inhibit Fn colonization to achieve this delaying effect.

AIM OF STUDY

This study explored the effect and mechanism of BXD in inhibiting Fn intestinal colonization to delay colitis-to-cancer transition.

MATERIALS AND METHODS

We constructed a mouse model of colitis-to-cancer transition by regularly gavaging Fn combined with azoxymethane (AOM)/dextran sodium sulfate (DSS), and administered BXD by gavage. We monitored the body weight of mice, measured the length and weight of their colons, and calculated the disease activity index (DAI) score. The growth status of colon tumors was observed by hematoxylin and eosin (H&E) staining, and the changes in gut microbiota in each group of mice were detected by 16S rDNA analysis. Immunohistochemistry was used to detect the expression of E-cadherin and β-catenin in colon tissues, and immunofluorescence was used to observe the infiltration of M2 macrophages in colon tissues. In cell experiments, we established a co-culture model of Fn and colon cancer cells and intervened with BXD-containing serum. Malignant behaviors such as cell proliferation, invasion, and migration were detected, as well as changes in their cell cycle. We examined the protein levels of E-cadherin, β-catenin, Axin2, and Cyclin D1 in each group were detected by Western blot. We used US1 strain (fadA-) as a control and observed the effects of BXD-containing serum on Fn attachment and invasion of colon cancer cells through attachment and invasion experiments.

RESULTS

BXD can inhibit the colitis-to-cancer transition in mice infected with Fn, reduce crypt structure damage, improve gut microbiota dysbiosis, upregulate E-cadherin and decrease β-catenin expression, and reduce infiltration of M2 macrophages, thus inhibiting the process of colitis-to-cancer transition. Cell experiments revealed that BXD-containing serum can inhibit the proliferation, migration, and invasion of colon cancer cells infected with Fn and regulate their cell cycle. More importantly, we found that BXD-containing serum can inhibit the binding of Fn's FadA adhesin to E-cadherin, reduce Fn's attachment and invasion of colon cancer cells, thereby downregulating the E-cadherin/β-catenin signaling pathway.

CONCLUSIONS

These findings show that BXD can inhibit Fn colonization by interfering with the binding of FadA to E-cadherin, reducing the activation of the E-cadherin/β-catenin signaling pathway, and ultimately delaying colitis-to-cancer transition.

Cytosolic Cadherin 4 promotes angiogenesis and metastasis in papillary thyroid cancer by suppressing the ubiquitination/degradation of β-catenin

BACKGROUND

Although the long-term prognosis of papillary thyroid cancer (PTC) is favorable, distant metastasis significantly compromises the prognosis and quality of life for patients with PTC. The Cadherin family plays a pivotal role in tumor metastasis; however, the involvement of Cadherin 4 (CDH4) in the metastatic cascade remains elusive.

METHODS

The expression and subcellular localization of CDH4 were determined through immunohistochemistry, immunofluorescence, and western blot analyses. The impact of CDH4 on cell migration, invasion, angiogenesis, and metastasis was assessed using transwell assays, tube formation assays, and animal experiments. Immunoprecipitation assay and mass spectrometry were employed to examine protein associations. The influence of CDH4 on the subcellular expression of β-catenin and active β-catenin was investigated via western blotting and immunofluorescence. Protein stability and ubiquitination assay were employed to verify the impact of CDH4 on β-catenin degradation. Rescue experiments were performed to ensure the significance of CDH4 in regulating nuclear β-catenin signaling.

RESULTS

CDH4 was found to be significantly overexpressed in PTC tissues and predominantly localized in the cytoplasm. Furthermore, the overexpression of CDH4 in tumor tissues is associated with lymph node metastasis in PTC patients. Cytosolic CDH4 promoted the migration, invasion, and lung metastasis of PTC cells and stimulated the angiogenesis and tumorigenesis of PTC; however, this effect could be reversed by Tegavivint, an antagonist of β-catenin. Mechanistically, cytosolic CDH4 disrupted the interaction between β-catenin and β-TrCP1, consequently impeding the ubiquitination process of β-catenin and activating the nuclear β-catenin signaling.

CONCLUSIONS

CDH4 induces PTC angiogenesis and metastasis via the inhibition of β-TrCP1-dependent ubiquitination of β-Catenin.

E-Cadherin Expression Varies Depending on the Location within the Primary Tumor and Is Higher in Colorectal Cancer with Lymphoid Follicles

Reliable indicators of cancer advancement have actively been sought recently. The detection of colorectal cancer progression markers is essential in improving diagnostic and therapeutic protocols. The aim of the study was to investigate the profile of E-cadherin expression in colorectal cancer tissue depending on the TNM staging and its correlation with several clinical and histopathological features. The study included 55 colorectal cancer patients admitted to the surgical ward for elective surgery. Tissue samples were obtained from resected specimens. Different distributions of E-cadherin expression within tumors were observed; the highest percentage of positive E-cadherin expression was found in the invasive front and in the tumor center. Additionally, the different cellular distribution of E-cadherin expression was noticed; weak membranous E-cadherin expression was the highest in the invasive front and in the budding sites, but a strong membranous pattern was most frequent in the tumor center. Various distributions of E-cadherin expression depending on cancer progression were also found; E-cadherin expression in node-positive patients was lower in the tumor center and in the tumor invasive front, whereas, in patients with distant metastases, the expression of E-Cadherin was lower in the budding sites. In patients with higher TNM stages, E-cadherin expression was lower within the tumor (in the budding sites, tumor center, and invasive front). In tumors with lymphoid follicles, E-cadherin expression was higher in all localizations within the primary tumor. E-cadherin expression in the tumor center was also lower in tumors with some higher tumor budding parameters (areas of poorly differentiated components and poorly differentiated clusters). E-cadherin expression was found to be lower at the tumor center in younger individuals, at the budding sites in men, and at the surrounding lymph nodes in rectal tumors. Low E-cadherin expression appears to be a reliable indicator of higher cancer staging and progression. When assessing the advancement of cancer, apart from the TNM classification, it is beneficial to also consider the expression of E-cadherin. High tumor budding, the poverty of lymphoid follicles, and low E-cadherin expression analyzed simultaneously may contribute to a reliable assessment of colorectal cancer staging. These three histopathological features complement each other, and their investigation, together with conventional tumor staging and grading, may be very helpful in predicting the prognosis of colorectal cancer patients and qualifying them for the best treatment. The role of E-cadherin in the diagnosis and treatment of colorectal cancer, as a part of a personalized medicine strategy, still requires comprehensive, prospective clinical evaluations to precisely target the optimal therapies for the right patients at the right time.

VE-Cadherin modulates β-catenin/TCF-4 to enhance Vasculogenic Mimicry

Vasculogenic Mimicry (VM) refers to the capacity to form a blood network from aggressive cancer cells in an independent way of endothelial cells, to provide nutrients and oxygen leading to enhanced microenvironment complexity and treatment failure. In a previous study, we demonstrated that VE-Cadherin and its phosphorylation at Y658 modulated kaiso-dependent gene expression (CCND1 and Wnt 11) through a pathway involving Focal Adhesion kinase (FAK). In the present research, using a proteomic approach, we have found that β-catenin/TCF-4 is associated with nuclear VE-cadherin and enhances the capacity of malignant melanoma cells to undergo VM in cooperation with VE-Cadherin; in addition, preventing the phosphorylation of Y658 of VE-cadherin upon FAK disabling resulted in VE-Cadherin/β-catenin complex dissociation, increased β-catenin degradation while reducing TCF-4-dependent genes transcription (C-Myc and Twist-1). Uveal melanoma cells knockout for VE-Cadherin loses β-catenin expression while the rescue of VE-Cadherin (but not of the phosphorylation defective VE-Cadherin Y658F mutant) permits stabilization of β-catenin and tumor growth reduction in vivo experiments. In vivo, the concomitant treatment with the FAK inhibitor PF-271 and the anti-angiogenic agent bevacizumab leads to a strong reduction in tumor growth concerning the single treatment. In conclusion, the anomalous expression of VE-Cadherin in metastatic melanoma cells (from both uveal and cutaneous origins), together with its permanent phosphorylation at Y658, favors the induction of the aggressive VM phenotype through the cooperation of β-catenin with VE-Cadherin and by enhancing TCF-4 genes-dependent transcription.

Role of Moonlighting Proteins in Disease: Analyzing the Contribution of Canonical and Moonlighting Functions in Disease Progression

The term moonlighting proteins refers to those proteins that present alternative functions performed by a single polypeptide chain acquired throughout evolution (called canonical and moonlighting, respectively). Over 78% of moonlighting proteins are involved in human diseases, 48% are targeted by current drugs, and over 25% of them are involved in the virulence of pathogenic microorganisms. These facts encouraged us to study the link between the functions of moonlighting proteins and disease. We found a large number of moonlighting functions activated by pathological conditions that are highly involved in disease development and progression. The factors that activate some moonlighting functions take place only in pathological conditions, such as specific cellular translocations or changes in protein structure. Some moonlighting functions are involved in disease promotion while others are involved in curbing it. The disease-impairing moonlighting functions attempt to restore the homeostasis, or to reduce the damage linked to the imbalance caused by the disease. The disease-promoting moonlighting functions primarily involve the immune system, mesenchyme cross-talk, or excessive tissue proliferation. We often find moonlighting functions linked to the canonical function in a pathological context. Moonlighting functions are especially coordinated in inflammation and cancer. Wound healing and epithelial to mesenchymal transition are very representative. They involve multiple moonlighting proteins with a different role in each phase of the process, contributing to the current-phase phenotype or promoting a phase switch, mitigating the damage or intensifying the remodeling. All of this implies a new level of complexity in the study of pathology genesis, progression, and treatment. The specific protein function involved in a patient's progress or that is affected by a drug must be elucidated for the correct treatment of diseases.

Working a second job: Cell adhesion proteins that moonlight in the nucleus

Cells are adept at sensing changes in their environment, transmitting signals internally to coordinate responses to external stimuli, and thereby influencing adaptive changes in cell states and behavior. Often, this response involves modulation of gene expression in the nucleus, which is seen largely as a physically separated process from the rest of the cell. Mechanosensing, whereby a cell senses physical stimuli, and integrates and converts these inputs into downstream responses including signaling cascades and gene regulatory changes, involves the participation of several macromolecular structures. Of note, the extracellular matrix (ECM) and its constituent macromolecules comprise an essential part of the cellular microenvironment, allowing cells to interact with each other, and providing both structural and biochemical stimuli sensed by adhesion transmembrane receptors. This highway of information between the ECM, cell adhesion proteins, and the cytoskeleton regulates cellular behavior, the disruption of which results in disease. Emerging evidence suggests a more direct role for some of these adhesion proteins in chromatin structure and gene regulation, RNA maturation and other non-canonical functions. While many of these discoveries were previously limited to observations of cytoplasmic-nuclear transport, recent advances in microscopy, and biochemical, proteomic and genomic technologies have begun to significantly enhance our understanding of the impact of nuclear localization of these proteins. This review will briefly cover known cell adhesion proteins that migrate to the nucleus, and their downstream functions. We will outline recent advances in this very exciting yet still emerging field, with impact ranging from basic biology to disease states like cancer.

Adherens junction proteins on the move—From the membrane to the nucleus in intestinal diseases

The function and structure of the mammalian epithelial cell layer is maintained by distinct intercellular adhesion complexes including adherens junctions (AJs), tight junctions, and desmosomes. The AJ is most integral for stabilizing cell-cell adhesion and conserving the structural integrity of epithelial tissues. AJs are comprised of the transmembrane protein E-cadherin and cytoplasmic catenin cofactors (α, β, γ, and p120-catenin). One organ where malfunction of AJ is a major contributor to disease states is the mammalian intestine. In the intestine, cell-cell adhesion complexes work synergistically to maintain structural integrity and homeostasis of the epithelium and prevent its malfunction. Consequently, when AJ integrity is compromised in the intestinal epithelium, the ensuing homeostatic disruption leads to diseases such as inflammatory bowel disease and colorectal carcinoma. In addition to their function at the plasma membrane, protein components of AJs also have nuclear functions and are thus implicated in regulating gene expression and intracellular signaling. Within the nucleus, AJ proteins have been shown to interact with transcription factors such as TCF/LEF and Kaiso (ZBTB33), which converge on the canonical Wnt signaling pathway. The multifaceted nature of AJ proteins highlights their complexity in modulating homeostasis and emphasizes the importance of their subcellular localization and expression in the mammalian intestine. In this review, we summarize the nuclear roles of AJ proteins in intestinal tissues; their interactions with transcription factors and how this leads to crosstalk with canonical Wnt signaling; and how nuclear AJ proteins are implicated in intestinal homeostasis and disease.

Class IIa histone deacetylase inhibition ameliorates acute kidney injury by suppressing renal tubular cell apoptosis and enhancing autophagy and proliferation

Expression and function of histone deacetylases (HDACs) vary with cell types and pathological conditions. Our recent studies showed that pharmacological targeting class IIa HDACs attenuated renal fibrosis, but the effect of class IIa HDAC inhibition on acute kidney injury (AKI) remains unknown. In this study, we found that four class IIa HDACs (4, 5, 7, 9) were highly expressed in the kidney of folic acid (FA) and ischemia/reperfusion (I/R)-induced AKI in mice. Administration of TMP269, a potent and selective class IIa HDAC inhibitor, improved renal function and reduced tubular cell injury and apoptosis, with concomitant suppression of HDAC4 and elevation of acetyl-histone H3. Mechanistical studies showed that TMP269 treatment inhibited FA and I/R-induced caspase-3 cleavage, Bax expression and p53 phosphorylation. Conversely, TMP269 administration preserved expression of E-cadherin, BMP7, Klotho and Bcl-2 in injured kidneys. Moreover, TMP269 was effective in promoting cellular autophagy as indicated by increased expression of Atg7, beclin-1, and LC3II, and promoted renal tubular cell proliferation as shown by increased number of proliferating cell nuclear antigen-positive cells and expression of cyclin E. Finally, blocking class IIa HDACs inhibited FA-and I/R-induced phosphorylation of extracellular signal-regulated kinases 1 and 2, and p38, two signaling pathways associated with the pathogenesis of AKI. Collectively, these results suggest that pharmacological inhibition of class IIa HDACs protects against AKI through ameliorating apoptosis, enhancing autophagy and promoting proliferation of renal tubular cells by targeting multiple signaling pathways.

Regulation of epithelial-mesenchymal transition by protein lysine acetylation

The epithelial-mesenchymal transition (EMT) is a vital driver of tumor progression. It is a well-known and complex trans-differentiation process in which epithelial cells undergo morphogenetic changes with loss of apical-basal polarity, but acquire spindle-shaped mesenchymal phenotypes. Lysine acetylation is a type of protein modification that favors reversibly altering the structure and function of target molecules via the modulation of lysine acetyltransferases (KATs), as well as lysine deacetylases (KDACs). To date, research has found that histones and non-histone proteins can be acetylated to facilitate EMT. Interestingly, histone acetylation is a type of epigenetic regulation that is capable of modulating the acetylation levels of distinct histones at the promoters of EMT-related markers, EMT-inducing transcription factors (EMT-TFs), and EMT-related long non-coding RNAs to control EMT. However, non-histone acetylation is a post-translational modification, and its effect on EMT mainly relies on modulating the acetylation of EMT marker proteins, EMT-TFs, and EMT-related signal transduction molecules. In addition, several inhibitors against KATs and KDACs have been developed, some of which can suppress the development of different cancers by targeting EMT. In this review, we discuss the complex biological roles and molecular mechanisms underlying histone acetylation and non-histone protein acetylation in the control of EMT, highlighting lysine acetylation as potential strategy for the treatment of cancer through the regulation of EMT.

Gene repression through epigenetic modulation by PPARA enhances hepatocellular proliferation

Peroxisome proliferator-activated receptor α (PPARA) is a key mediator of lipid metabolism and inflammation. Activation of PPARA in rodents causes hepatocyte proliferation, but the underlying mechanism is poorly understood. This study focused on genes repressed by PPARA and analyzed the mechanism by which PPARA promotes hepatocyte proliferation in mice. Activation of PPARA by agonist treatment was autoregulated, and induced expression of the epigenetic regulator UHRF1 via activation of the newly described PPARA target gene E2f8, which, in turn, regulates Uhrf1. UHRF1 strongly repressed the expression of CDH1 via methylation of the Cdh1 promoter marked with H3K9me3. Repression of CDH1 by PPARA activation was reversed by PPARA deficiency or knockdown of E2F8 or UHRF1. Furthermore, a forced expression of CDH1 inhibited expression of the Wnt signaling target genes such as Myc after PPARA activation, and suppressed hepatocyte hyperproliferation. These results demonstrate that the PPARA-E2F8-UHRF1-CDH1 axis causes epigenetic regulation of hepatocyte proliferation.

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PPARA activation induces the UHRF1 expression via novel PPARA target gene E2f8

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Induction of UHRF1 by PPARA activation represses Cdh1 gene marked with H3K9me3

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CDH1 suppresses hepatocyte proliferation after PPARA activation

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Autoinduction of PPARA by agonist enhances cell proliferation via E2F8-UHRF1-CDH1

Bacteroides fragilis Toxin Induces Intestinal Epithelial Cell Secretion of Interleukin-8 by the E-Cadherin/β-Catenin/NF-κB Dependent Pathway

Enterotoxigenic Bacteroides fragilis (ETBF) has emerged as a gut microbiome pathogen that can promote colitis associated cancer in humans. ETBF secretes the metalloprotease, B. fragilis toxin (BFT), which can induce ectodomain cleavage of E-cadherin and IL-8 secretion through the β-catenin, NF-κB, and MAPK pathways in intestinal epithelial cells. However, it is still unclear whether E-cadherin cleavage is required for BFT induced IL-8 secretion and the relative contribution of these signaling pathways to IL-8 secretion. Using siRNA knockdown and CRISPR knockout studies, we found that E-cadherin cleavage is required for BFT mediated IL-8 secretion. In addition, genetic ablation of β-catenin indicates that β-catenin is required for the BFT induced increase in transcriptional activity of NF-κB, p65 nuclear localization and early IL-8 secretion. These results suggest that BFT induced β-catenin signaling is upstream of NF-κB activation. However, despite β-catenin gene disruption, BFT still activated the MAPK pathway, suggesting that the BFT induced activation of the MAPK signaling pathway is independent from the E-cadherin/β-catenin/NF-κB pathway. These findings show that E-cadherin and β-catenin play a critical role in acute inflammation following ETBF infection through the inflammatory response to BFT in intestinal epithelial cells.

S100A4/TCF Complex Transcription Regulation Drives Epithelial-Mesenchymal Transition in Chronic Sinusitis Through Wnt/GSK-3β/β-Catenin Signaling

Epithelial-mesenchymal transition (EMT) is thought to be involved in the tissue remodeling and long-term inflammatory process of chronic sinusitis (CRS), but the driving mechanism is still unclear. Using high-resolution mass spectrometry, we performed a proteomic screen of CRS nasal mucosal tissue to identify differentially expressed proteins. Data are available via ProteomeXchange with identifier PXD030884. Specifically, we identified S100 calcium binding protein A4 (S100A4), an effective factor in inflammation-related diseases, and its downstream protein closely related to tissue fibrosis collagen type I alpha 1 chain (COL1A1), which suggested its involvement in nasal mucosal tissue remodeling. In addition, stimulation of human nasal epithelial cells (HNEpCs) with lipopolysaccharide (LPS) mimicked the inflammatory environment of CRS and showed that S100A4 is involved in regulating EMT and thus accelerating tissue remodeling in the nasal mucosa, both in terms of increased cell motility and overexpression of mesenchymal-type proteins. Additionally, we further investigated the regulation mechanism of S100A4 involved in EMT in CRS. Our research results show that in the inflammatory environment of CRS nasal mucosal epithelial cells, TCF-4 will target to bind to S100A4 and regulate its transcription. The transcription of S100A4 in turn affects the execution of the important signaling pathway in EMT, the Wnt/GSK-3β/β-catenin pathway, through the TCF-4/β-catenin complex. In conclusion, this study confirmed that the expression of S100A4 was significantly increased during the progressive EMT process of CRS mucosal epithelial cells, and revealed that the transcriptional regulation of S100A4 plays an important role in the occurrence and development of EMT. This finding will help us to better understand the pathogenesis behind the remodeling in CRS patients, and identify target molecules for the treatment of CRS.

Genetic Code Expansion Tools to Study Lysine Acylation

Lysine acylation is a ubiquitous protein modification that controls various aspects of protein function, such as the activity, localization, and stability of enzymes. Mass spectrometric identification of lysine acylations has witnessed tremendous improvements in sensitivity over the last decade, facilitating the discovery of thousands of lysine acylation sites in proteins involved in all essential cellular functions across organisms of all domains of life. However, the vast majority of currently known acylation sites are of unknown function. Semi-synthetic methods for installing lysine derivatives are ideally suited for in vitro experiments, while genetic code expansion (GCE) allows the installation and study of such lysine modifications, especially their dynamic properties, in vivo. An overview of the current state of the art is provided, and its potential is illustrated with case studies from recent literature. These include the application of engineered enzymes and GCE to install lysine modifications or photoactivatable crosslinker amino acids. Their use in the context of central metabolism, bacterial and viral pathogenicity, the cytoskeleton and chromatin dynamics, is investigated.

Protein Acetylation at the Interface of Genetics, Epigenetics and Environment in Cancer

Metabolic reprogramming is an emerging hallmark of cancer and is driven by abnormalities of oncogenes and tumor suppressors. Accelerated metabolism causes cancer cell aggression through the dysregulation of rate-limiting metabolic enzymes as well as by facilitating the production of intermediary metabolites. However, the mechanisms by which a shift in the metabolic landscape reshapes the intracellular signaling to promote the survival of cancer cells remain to be clarified. Recent high-resolution mass spectrometry-based proteomic analyses have spotlighted that, unexpectedly, lysine residues of numerous cytosolic as well as nuclear proteins are acetylated and that this modification modulates protein activity, sublocalization and stability, with profound impact on cellular function. More importantly, cancer cells exploit acetylation as a post-translational protein for microenvironmental adaptation, nominating it as a means for dynamic modulation of the phenotypes of cancer cells at the interface between genetics and environments. The objectives of this review were to describe the functional implications of protein lysine acetylation in cancer biology by examining recent evidence that implicates oncogenic signaling as a strong driver of protein acetylation, which might be exploitable for novel therapeutic strategies against cancer.

Regulation of SIRT2 by Wnt/β-catenin signaling pathway in colorectal cancer cells

Activation of the Wnt/β-catenin pathway is one of the hallmarks of colorectal cancer (CRC). Sirtuin 2 (SIRT2) protein has been shown to inhibit CRC proliferation. Previously, we reported that SIRT2 plays an important role in the maintenance of normal intestinal cell homeostasis. Here, we show that SIRT2 is a direct target gene of Wnt/β-catenin signaling in CRC cells. Inhibition or knockdown of Wnt/β-catenin increased SIRT2 promoter activity and mRNA and protein expression, whereas activation of Wnt/β-catenin decreased SIRT2 promoter activity and expression. β-Catenin was recruited to the promoter of SIRT2 and transcriptionally regulated SIRT2 expression. Wnt/β-catenin inhibition increased mitochondrial oxidative phosphorylation (OXPHOS) and CRC cell differentiation. Moreover, inhibition of OXPHOS attenuated the differentiation of CRC cells induced by Wnt/β-catenin inhibition. In contrast, inhibition or knockdown of SIRT2 decreased, while overexpression of SIRT2 increased, OXPHOS activity and differentiation in CRC cells. Consistently, inhibition or knockdown or SIRT2 attenuated the differentiation induced by Wnt/β-catenin inhibition. These results demonstrate that SIRT2 is a novel target gene of the Wnt/β-catenin signaling and contributes to the differentiation of CRC cells.

A biomimetic model of 3D fluid extracellular macromolecular crowding microenvironment fine-tunes ovarian cancer cells dissemination phenotype

An early fundamental step in ovarian cancer progression is the dissemination of cancer cells through liquid environments, one of them being cancer ascites accumulated in the peritoneal cavity. These biological fluids are highly crowded with a high total macromolecule concentration. This biophysical property of fluids is widely used in tissue engineering for a few decades now, yet is largely underrated in cancer biomimetic models. To unravel the role of fluids extracellular macromolecular crowding (MMC), we exposed ovarian cancer cells (OCC) to high molecular weight inert polymer solutions. High macromolecular composition of extracellular liquid presented a differential effect: i) it impeded non-adherent OCC aggregation in suspension and, decreased their adhesion; ii) it promoted adherent OCC migration by decreasing extracellular matrix deposition. Besides, there seemed to be a direct link between the extracellular MMC and intracellular processes, especially the actin cytoskeleton organization and the nucleus morphology. In conclusion, extracellular fluid MMC orients OCC dissemination phenotype. Integrating MMC seems crucial to produce more relevant mimetic 3D in vitro fluid models to study ovarian dissemination but also to screen drugs.

FadA promotes DNA damage and progression of Fusobacterium nucleatum-induced colorectal cancer through up-regulation of chk2

Background

Globally, colorectal cancer (CRC) affects more than 1 million people each year. In addition to non-modifiable and other environmental risk factors, Fusobacterium nucleatum infection has been linked to CRC recently. In this study, we explored mechanisms underlying the role of Fusobacterium nucleatum infection in the progression of CRC in a mouse model.

Methods

C57BL/6 J-Adenomatous polyposis coli (APC) Min/J mice [APC (Min/+)] were treated with Fusobacterium nucleatum (10⁹ cfu/mL, 0.2 mL/time/day, i.g., 12 weeks), saline, or FadA knockout (FadA−/−) Fusobacterium nucleatum. The number, size, and weight of CRC tumors were determined in isolated tumor masses. The human CRC cell lines HCT29 and HT116 were treated with lentiviral vectors overexpressing chk2 or silencing β-catenin. DNA damage was determined by Comet assay and γH2AX immunofluorescence assay and flow cytometry. The mRNA expression of chk2 was determined by RT-qPCR. Protein expression of FadA, E-cadherin, β-catenin, and chk2 were determined by Western blot analysis.

Results

Fusobacterium nucleatum treatment promoted DNA damage in CRC in APC (Min/+) mice. Fusobacterium nucleatum also increased the number of CRC cells that were in the S phase of the cell cycle. FadA−/− reduced tumor number, size, and burden in vivo. FadA−/− also reduced DNA damage, cell proliferation, expression of E-cadherin and chk2, and cells in the S phase. Chk2 overexpression elevated DNA damage and tumor growth in APC (Min/+) mice.

Conclusions

In conclusion, this study provided evidence that Fusobacterium nucleatum induced DNA damage and cell growth in CRC through FadA-dependent activation of the E-cadherin/β-catenin pathway, leading to up-regulation of chk2.

(Phospho)proteomic Profiling of Microsatellite Unstable CRC Cells Reveals Alterations in Nuclear Signaling and Cholesterol Metabolism Caused by Frameshift Mutation of NMD Regulator UPF3A

DNA mismatch repair-deficient colorectal cancers (CRCs) accumulate numerous frameshift mutations at repetitive sequences recognized as microsatellite instability (MSI). When coding mononucleotide repeats (cMNRs) are affected, tumors accumulate frameshift mutations and premature termination codons (PTC) potentially leading to truncated proteins. Nonsense-mediated RNA decay (NMD) can degrade PTC-containing transcripts and protect from such faulty proteins. As it also regulates normal transcripts and cellular physiology, we tested whether NMD genes themselves are targets of MSI frameshift mutations. A high frequency of cMNR frameshift mutations in the UPF3A gene was found in MSI CRC cell lines (67.7%), MSI colorectal adenomas (55%) and carcinomas (63%). In normal colonic crypts, UPF3A expression was restricted to single chromogranin A-positive cells. SILAC-based proteomic analysis of KM12 CRC cells revealed UPF3A-dependent down-regulation of several enzymes involved in cholesterol biosynthesis. Furthermore, reconstituted UPF3A expression caused alterations of 85 phosphosites in 52 phosphoproteins. Most of them (38/52, 73%) reside in nuclear phosphoproteins involved in regulation of gene expression and RNA splicing. Since UPF3A mutations can modulate the (phospho)proteomic signature and expression of enzymes involved in cholesterol metabolism in CRC cells, UPF3A may influence other processes than NMD and loss of UPF3A expression might provide a growth advantage to MSI CRC cells.

SIRT2 Contributes to the Regulation of Intestinal Cell Proliferation and Differentiation

BACKGROUND AND AIMS

Intestinal mucosa undergoes a continual process of proliferation, differentiation, and apoptosis. Disruption of this homeostasis is associated with disorders such as inflammatory bowel disease (IBD). We investigated the role of Sirtuin 2 (SIRT2), a NAD-dependent protein deacetylase, in intestinal epithelial cell (IEC) proliferation and differentiation and the mechanism by which SIRT2 contributes to maintenance of intestinal cell homeostasis.

METHODS

IECs were collected from SIRT2-deficient mice and patients with IBD. Expression of SIRT2, differentiation markers (mucin2, intestinal alkaline phosphatase, villin, Na,K-ATPase, and lysozyme) and Wnt target genes (EPHB2, AXIN2, and cyclin D1) was determined by western blot, real-time RT-PCR, or immunohistochemical (IHC) staining. IECs were treated with TNF or transfected with siRNA targeting SIRT2. Proliferation was determined by villus height and crypt depth, and Ki67 and cyclin D1 IHC staining. For studies using organoids, intestinal crypts were isolated.

RESULTS

Increased SIRT2 expression was localized to the more differentiated region of the intestine. In contrast, SIRT2 deficiency impaired proliferation and differentiation and altered stemness in the small intestinal epithelium ex vivo and in vivo. SIRT2-deficient mice showed decreased intestinal enterocyte and goblet cell differentiation but increased the Paneth cell lineage and increased proliferation of IECs. Moreover, we found that SIRT2 inhibits Wnt/β-catenin signaling, which critically regulates IEC proliferation and differentiation. Consistent with a distinct role for SIRT2 in maintenance of gut homeostasis, intestinal mucosa from IBD patients exhibited decreased SIRT2 expression.

CONCLUSION

We demonstrate that SIRT2, which is decreased in intestinal tissues from IBD patients, regulates Wnt-β-catenin signaling and is important for maintenance of IEC proliferation and differentiation.

Relationship between SDC1 and cadherin signalling activation in cancer

E-cadherin and SDC1 are markers of epithelial-to-mesenchymal transition (EMT) that can be used to assess tumour prognosis. SDC1 has different effects in various types of cancers. On the one hand, reduced expression of SDC1 can leads to advantage stages of some cancers, such as gastric and colorectal cancer. On the other hand, SDC1 overexpression can also promote the growth and proliferation of cancer cells in pancreatic and breast cancer. However, the function of SDC1 is influenced and regulated by many factors. Exfoliated extracellular domain HS chain can mediate the function of SDC1 and play an important role in the occurrence and development of cancer. SDC1 binds to various ligands and influences the growth and reproduction of cancer cells via the activation of Wnt, the long isoform of FLICE-inhibitory protein (FLIP long), vascular endothelial growth factor receptor (VEGFR), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) and MAPK/c-Jun N-terminal kinase (JNK) and other pathways. Cadherins occur in several types, but this review focuses on classical cadherins. N-cadherin and P-cadherin are activated during tumour development, whereas E-cadherin is a tumour suppressor. The cellular signalling pathways involved in classical cadherins, such as Wnt and VEGFR pathways, are also related to SDC1. The activation of E-cadherin caused by SDC1 knockdown has also been observed. Despite this evidence, no articles regarding the relationship of SDC1 and cadherin activation have been published. This review summarises the expressions of these two molecules in different cancers and analyses their possible relationship to provide insights into future cancer research and clinical treatment.

Basil polysaccharide inhibits hypoxia-induced hepatocellular carcinoma metastasis and progression through suppression of HIF-1α-mediated epithelial-mesenchymal transition

Invasion and metastasis of cancerous cells affects the treatment and prognosis of hepatocellular carcinoma (HCC). HIF-1α-induced epithelial-mesenchymal transition (EMT) is a critical process associated with cancer metastasis. Basil polysaccharide (BPS), one of the major active ingredients isolated from Basil (Ocimum basilicum L.), has been identified to possess an antitumor activity for HCC. In our current study, BPS was obtained by water extraction and ethanol precipitation method and the characterization was analyzed through ultraviolet absorption spectra and Fourier-transform infrared spectrum. A CoCl₂-induced hypoxia model and a HCC cell line-derived xenograft (CDX) model were used to explore the anti-metastasis efficacy and the mechanism that underlies the antitumor activity of BPS. The results showed that hypoxia could facilitate EMT and promote HCC cells migration and/or invasion. Conversely, BPS inhibited the progression and metastasis of tumor, as well as reversed EMT by causing cytoskeletal remodeling under hypoxic conditions. Moreover, BPS alleviated tumor hypoxia by targeting HIF1α, and the mesenchymal markers (β-catenin, N-cadherin and vimentin) were down-regulated, while the epithelial markers (E-cadherin, VMP1 and ZO-1) were up-regulated after BPS treatment under hypoxic conditions. Thus, these results suggested that BPS may be a valuable option for use in clinical treatment of HCC and other malignant tumors.

[Nucleus translocation of membrane/cytoplasm proteins in tumor cells]

Proteins are the physical basis of life and perform all kinds of life activities. Proteins have different orientations and function in different tissues. The same protein, located in different subcellular regions, can perform different and even opposite functions. Both functional and structural proteins are capable of undergoing re-localization which can directly or indirectly participate in signal transduction. Due to abnormal transduction of signals during carcinogenesis, the proteins originally expressed in the cytoplasm are translocated into the nucleus and lead to functional changes in the tumor tissue. The changes of protein localization are affected by many factors, including the interaction between proteins, expression level of proteins and the cleaved intracellular domain of transmembrane protein.