DEAR1 is a chromosome 1p35 tumor suppressor and master regulator of TGF-β-driven epithelial-mesenchymal transition

SLC14A1 and TGF-β signaling: a feedback loop driving EMT and colorectal cancer metachronous liver metastasis

BACKGROUND

Colorectal cancer (CRC) metachronous liver metastasis is a significant clinical challenge, largely attributable to the late detection and the intricate molecular mechanisms that remain poorly understood. This study aims to elucidate the role of Solute Carrier Family 14 Member 1 (SLC14A1) in the pathogenesis and progression of CRC metachronous liver metastasis.

METHODS

We conducted a comprehensive analysis of CRC patient data from The Cancer Genome Atlas and GSE40967 databases, focusing on the differential expression of genes associated with non-metachronous liver metastasis and metachronous liver metastasis. Functional assays, both in vitro and in vivo, were performed to assess the biological impact of SLC14A1 modulation in CRC cells. Gene set enrichment analysis, molecular assays and immunohistochemical analyses on clinical specimens were employed to unravel the underlying mechanisms through which SLC14A1 exerts its effects.

RESULTS

SLC14A1 was identified as a differentially expressed gene, with its overexpression significantly correlating with poor relapse-free and overall survival. Mechanistically, elevated SLC14A1 levels enhanced CRC cell invasiveness and migratory abilities, corroborated by upregulated TGF-β/Smad signaling and Epithelial-Mesenchymal Transition. SLC14A1 interacted with TβRII and stabilized TβRII protein, impeding its Smurf1-mediated K48-linked ubiquitination and degradation, amplifying TGF-β/Smad signaling. Furthermore, TGF-β1 reciprocally elevated SLC14A1 mRNA expression, with Snail identified as a transcriptional regulator, binding downstream of SLC14A1's transcription start site, establishing a positive feedback loop. Clinically, SLC14A1, phosphorylated Smad2, and Snail were markedly upregulated in CRC patients with metachronous liver metastasis, underscoring their potential as prognostic markers.

CONCLUSIONS

Our findings unveil SLC14A1 as a critical regulator in CRC metachronous liver metastasis, providing novel insights into the molecular crosstalk between SLC14A1 and TGF-β/Smad signaling. These discoveries not only enhance our understanding of CRC metachronous liver metastasis pathogenesis, but also highlight SLC14A1 as a promising target for therapeutic intervention and predictive marker.

Emerging roles of tripartite motif family proteins (TRIMs) in breast cancer

Breast cancer (BC) is the most common malignant tumor worldwide. Despite enormous progress made in the past decades, the underlying mechanisms of BC remain further illustrated. Recently, TRIM family proteins proved to be engaged in BC progression through regulating various aspects. Here we reviewed the structures and basic functions of TRIM family members and first classified them into three groups according to canonical polyubiquitination forms that they could mediate: K48- only, K63- only, and both K48- and K63-linked ubiquitination. Afterwards, we focused on the specific biological functions and mechanisms of TRIMs in BCs, including tumorigenesis and invasiveness, drug sensitivity, tumor immune microenvironment (TIME), cell cycle, and metabolic reprogramming. We also explored the potential of TRIMs as novel biomarkers for predicting prognosis and future therapeutic targets in BC.

The cross talk of ubiquitination and chemotherapy tolerance in colorectal cancer

Ubiquitination, a highly adaptable post-translational modification, plays a pivotal role in maintaining cellular protein homeostasis, encompassing cancer chemoresistance-associated proteins. Recent findings have indicated a potential correlation between perturbations in the ubiquitination process and the emergence of drug resistance in CRC cancer. Consequently, numerous studies have spurred the advancement of compounds specifically designed to target ubiquitinates, offering promising prospects for cancer therapy. In this review, we highlight the role of ubiquitination enzymes associated with chemoresistance to chemotherapy via the Wnt/β-catenin signaling pathway, epithelial-mesenchymal transition (EMT), and cell cycle perturbation. In addition, we summarize the application and role of small compounds that target ubiquitination enzymes for CRC treatment, along with the significance of targeting ubiquitination enzymes as potential cancer therapies.

Emetine dihydrochloride alleviated radiation-induced lung injury through inhibiting EMT

Radiation-induced lung injury (RILI), divided into early radiation pneumonia (RP) and late radiation-induced pulmonary fibrosis (RIPF), is a common serious disease after clinical chest radiotherapy or nuclear accident, which seriously threatens the life safety of patients. There has been no effective prevention or treatment strategy till now. Epithelial-mesenchymal transition (EMT) is a key step in the occurrence and development of RILI. In this study, we demonstrated that emetine dihydrochloride (EDD) alleviated RILI through inhibiting EMT. We found that EDD significantly attenuated EMT-related markers, reduced Smad3 phosphorylation expression after radiation. Then, for the first time, we observed EDD alleviated lung hyperaemia and reduced collagen deposit induced by irradiation, providing protection against RILI. Finally, it was found that EDD inhibited radiation-induced EMT in lung tissues. Our study suggested that EDD alleviated RILI through inhibiting EMT by blocking Smad3 signalling pathways. In summary, our results indicated that EDD is a novel potential radioprotector for RILI.

Intricate confrontation: Research progress and application potential of TRIM family proteins in tumor immune escape

BACKGROUND

Tripartite motif (TRIM) family proteins have more than 80 members and are widely found in various eukaryotic cells. Most TRIM family proteins participate in the ubiquitin-proteasome degradation system as E3-ubiquitin ligases; therefore, they play pivotal regulatory roles in the occurrence and development of tumors, including tumor immune escape. Due to the diversity of functional domains of TRIM family proteins, they can extensively participate in multiple signaling pathways of tumor immune escape through different substrates. In current research and clinical contexts, immune escape has become an urgent problem. The extensive participation of TRIM family proteins in curing tumors or preventing postoperative recurrence and metastasis makes them promising targets.

AIM OF REVIEW

The aim of the review is to make up for the gap in the current research on TRIM family proteins and tumor immune escape and propose future development directions according to the current progress and problems.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This up-to-date review summarizes the characteristics and biological functions of TRIM family proteins, discusses the mechanisms of TRIM family proteins involved in tumor immune escape, and highlights the specific mechanism from the level of structure-function-molecule-pathway-phenotype, including mechanisms at the level of protein domains and functions, at the level of molecules and signaling pathways, and at the level of cells and microenvironments. We also discuss the application potential of TRIM family proteins in tumor immunotherapy, such as possible treatment strategies for combination targeting TRIM family protein drugs and checkpoint inhibitors for improving cancer treatment.

Molecular signature to predict quality of life and survival with glioblastoma using Multiview omics model

Glioblastoma multiforme (GBM) patients show a variety of signs and symptoms that affect their quality of life (QOL) and self-dependence. Since most existing studies have examined prognostic factors based only on clinical factors, there is a need to consider the value of integrating multi-omics data including gene expression and proteomics with clinical data in identifying significant biomarkers for GBM prognosis. Our research aimed to isolate significant features that differentiate between short-term (≤ 6 months) and long-term (≥ 2 years) GBM survival, and between high Karnofsky performance scores (KPS ≥ 80) and low (KPS ≤ 60), using the iterative random forest (iRF) algorithm. Using the Cancer Genomic Atlas (TCGA) database, we identified 35 molecular features composed of 19 genes and 16 proteins. Our findings propose molecular signatures for predicting GBM prognosis and will improve clinical decisions, GBM management, and drug development.

Activation of ACLY by SEC63 deploys metabolic reprogramming to facilitate hepatocellular carcinoma metastasis upon endoplasmic reticulum stress

BACKGROUND

Tumor cells display augmented capability to maintain endoplasmic reticulum (ER) homeostasis and hijack ER stress pathway for malignant phenotypes under microenvironmental stimuli. Metabolic reprogramming is a well-known hallmark for tumor cells to provide specific adaptive traits to the microenvironmental alterations. However, it's unknown how tumor cells orchestrate metabolic reprogramming and tumor progression in response to ER stress. Herein, we aimed to explore the pivotal roles of SEC63-mediated metabolic remodeling in hepatocellular carcinoma (HCC) cell metastasis after ER stress.

METHODS

The expression levels of SEC63 in HCC tissues and adjacent non-cancerous tissues were determined by immunohistochemistry and western blot. The regulatory roles of SEC63 in HCC metastasis were investigated both in vitro and in vivo by RNA-sequencing, metabolites detection, immunofluorescence, and transwell migration/invasion analyses. GST pull-down, immunoprecipitation/mass spectrometry and in vivo ubiquitination/phosphorylation assay were conducted to elucidate the underlying molecular mechanisms.

RESULTS

We identified SEC63 as a new regulator of HCC cell metabolism. Upon ER stress, the phosphorylation of SEC63 at T537 by IRE1α pathway contributed to SEC63 activation. Then, the stability of ACLY was upregulated by SEC63 to increase the supply of acetyl-CoA and lipid biosynthesis, which are beneficial for improving ER capacity. Meanwhile, SEC63 also entered into nucleus for increasing nuclear acetyl-CoA production to upregulate unfolded protein response targets to improve ER homeostasis. Importantly, SEC63 coordinated with ACLY to epigenetically modulate expression of Snail1 in the nucleus. Consequently, SEC63 promoted HCC cell metastasis and these effects were reversed by ACLY inhibition. Clinically, SEC63 expression was significantly upregulated in HCC tissue specimens and was positively correlated with ACLY expression. Importantly, high expression of SEC63 predicted unfavorable prognosis of HCC patients.

CONCLUSIONS

Our findings revealed that SEC63-mediated metabolic reprogramming plays important roles in keeping ER homeostasis upon stimuli in HCC cells. Meanwhile, SEC63 coordinates with ACLY to upregulate the expression of Snail1, which further promotes HCC metastasis. Metastasis is crucial for helping cancer cells seek new settlements upon microenvironmental stimuli. Taken together, our findings highlight a cancer selective adaption to ER stress as well as reveal the potential roles of the IRE1α-SEC63-ACLY axis in HCC treatment.

Comprehensive analysis of novel prognosis-related proteomic signature effectively improve risk stratification and precision treatment for patients with cervical cancer

OBJECTIVE

Cervical cancer (CC) is one of the most common types of malignant female cancer, and its incidence and mortality are not optimistic. Protein panels can be a powerful prognostic factor for many types of cancer. The purpose of our study was to investigate a proteomic panel to predict the survival of patients with common CC.

METHODS AND RESULTS

The protein expression and clinicopathological data of CC were downloaded from The Cancer Proteome Atlas and The Cancer Genome Atlas database, respectively. We selected the prognosis-related proteins (PRPs) by univariate Cox regression analysis and found that the results of functional enrichment analysis were mainly related to apoptosis. We used Kaplan-Meier analysis and multivariable Cox regression analysis further to screen PRPs to establish a prognostic model, including BCL2, SMAD3, and 4EBP1-pT70. The signature was verified to be independent predictors of OS by Cox regression analysis and the area under curves. Nomogram and subgroup classification were established based on the signature to verify its clinical application. Furthermore, we looked for the co-expressed proteins of three-protein panel as potential prognostic proteins.

CONCLUSION

A proteomic signature independently predicted OS of CC patients, and the predictive ability was better than the clinicopathological characteristics. This signature can help improve prediction for clinical outcome and provides new targets for CC treatment.

Tumor suppressor DEAR1 regulates mammary epithelial cell fate and predicts early onset and metastasis in triple negative breast cancer

Triple negative breast cancer (TNBC) is a disease of poor prognosis, with the majority classified as the basal-like subtype associated with epithelial-mesenchymal transition and metastasis. Because basal breast cancers originate from proliferative luminal progenitor-like cells upon dysregulation of proper luminal differentiation, genes regulating luminal-basal transition are critical to elucidate novel therapeutic targets to improve TNBC outcomes. Herein we demonstrate that the tumor suppressor DEAR1/TRIM62 is a critical regulator of luminal cell fate. DEAR1 loss in human mammary epithelial cells results in significantly enhanced mammosphere formation that is accelerated in the presence of TGF-β/SMAD3 signaling. Mammospheres formed following DEAR1 loss are enriched for ALDH1A1 and CK5 expression, EpCAM^-/CD49f⁺ and CD44^high/24^low basal-like epithelial cells, indicating that DEAR1 regulates stem/progenitor cell properties and luminal-basal progenitor transition. We show that DEAR1 maintains luminal differentiation as a novel ubiquitin ligase for SNAI2/SLUG, a master regulator driving stemness and generation of basal-like progenitor populations. We also identify a significant inverse correlation between DEAR1 and SNAI2 expression in a 103 TNBC case cohort and show that low DEAR1 expression significantly correlates with young age of onset and shorter time to metastasis, suggesting DEAR1 could serve as a biomarker to stratify early onset TNBCs for targeted stem cell therapies.

Fucoxanthin prevents breast cancer metastasis by interrupting circulating tumor cells adhesion and transendothelial migration

Metastasis is the leading cause of cancer-related death and a critical challenge in improving cancer treatment today. Circulating tumor cells (CTCs) adhesion to and across the vascular endothelium are critical steps in the establishment of micrometastatic foci away from the primary tumor. Therefore, we believe that interrupting CTCs adhesion to endothelium and transendothelial migration may efficiently prevent cancer metastasis. Fucoxanthin (Fx) is an algal carotenoid widely distributed in brown algae, macroalgae, and diatoms. Previous studies have found that Fx has various pharmacological activities, including antidiabetic, antioxidant, anti-inflammatory, anti-obesity, antimalarial, anticancer, and so on. However, it remains unclear whether Fx has a preventive effect on cancer metastasis. Here, we found that Fx interrupts breast cancer cells MCF-7 adhesion to endothelium and transendothelial migration, thus inhibiting CTCs-based pulmonary metastasis in vivo. The hetero-adhesion assay showed that Fx significantly inhibited the expression of inflammatory factor-induced cell adhesion molecules (CAMs) and the resulting adhesion between MCF-7 cells and endothelial cells. The wound-healing and transwell assays showed that Fx significantly inhibited the motility, invasion, and transendothelial migration abilities of MCF-7 cells. However, the same concentration of Fx did not significantly alter the cell viability, cell cycle, apoptosis, and ROS of breast cancer cells, thus excluding the possibility that Fx inhibits MCF-7 cell adhesion and transendothelial migration through cytotoxicity. Mechanistically, Fx inhibits the expression of CAMs on endothelial cells by inhibiting the NF-кB signaling pathway by down-regulating the phosphorylation level of IKK-α/β, IкB-α, and NF-кB p65. Fx inhibits transendothelial migration of MCF-7 cells by inhibiting Epithelial-to-mesenchymal transition (EMT), PI3K/AKT, and FAK/Paxillin signaling pathways. Moreover, we demonstrated that Fx significantly inhibits the formation of lung micrometastatic foci in immunocompetent syngeneic mouse breast cancer metastasis models. We also showed that Fx enhances antitumor immune responses by substantially increasing the subsets of cytotoxic T lymphocytes in the peripheral immune system. This new finding provides a basis for the application of Fx in cancer metastatic chemoprevention and suggests that interruption of the CTCs adhesion to endothelium and transendothelial migration may serve as a new avenue for cancer metastatic chemoprevention.

Regulation of transforming growth factor-β signaling as a therapeutic approach to treating colorectal cancer

According to data from 2020, Slovakia has long been among the top five countries with the highest incidence rate of colorectal cancer (CRC) worldwide, and the rate is continuing to rise every year. In approximately 80% of CRC cases, allelic loss (loss of heterozygosity, LOH) occurs in the long arm of chromosome 18q. The most important genes that can be silenced by 18q LOH or mutations are small mothers against decapentaplegic homolog (SMAD) 2 and SMAD4, which are intracellular mediators of transforming growth factor (TGF)-β superfamily signals. TGF-β plays an important role in the pro-oncogenic processes, including such properties as invasion, epithelial-mesenchymal transition (commonly known as EMT), promotion of angiogenesis, and immunomodulatory effects. Several recent studies have reported that activation of TGF-β signaling is related to drug resistance in CRC. Because the mechanisms of drug resistance are different between patients in different stages of CRC, personalized treatment is more effective. Therefore, knowledge of the activation and inhibition of factors that affect the TGF-β signaling pathway is very important.

Regulation of transforming growth factor-β signaling as a therapeutic approach to treating colorectal cancer

According to data from 2020, Slovakia has long been among the top five countries with the highest incidence rate of colorectal cancer (CRC) worldwide, and the rate is continuing to rise every year. In approximately 80% of CRC cases, allelic loss (loss of heterozygosity, LOH) occurs in the long arm of chromosome 18q. The most important genes that can be silenced by 18q LOH or mutations are small mothers against decapentaplegic homolog (SMAD) 2 and SMAD4, which are intracellular mediators of transforming growth factor (TGF)-β superfamily signals. TGF-β plays an important role in the pro-oncogenic processes, including such properties as invasion, epithelial-mesenchymal transition (commonly known as EMT), promotion of angiogenesis, and immunomodulatory effects. Several recent studies have reported that activation of TGF-β signaling is related to drug resistance in CRC. Because the mechanisms of drug resistance are different between patients in different stages of CRC, personalized treatment is more effective. Therefore, knowledge of the activation and inhibition of factors that affect the TGF-β signaling pathway is very important.

Anoikis resistance in diffuse glioma: The potential therapeutic targets in the future

Glioma is the most common malignant intracranial tumor and exhibits diffuse metastasis and a high recurrence rate. The invasive property of glioma results from cell detachment. Anoikis is a special form of apoptosis that is activated upon cell detachment. Resistance to anoikis has proven to be a protumor factor. Therefore, it is suggested that anoikis resistance commonly occurs in glioma and promotes diffuse invasion. Several factors, such as integrin, E-cadherin, EGFR, IGFR, Trk, TGF-β, the Hippo pathway, NF-κB, eEF-2 kinase, MOB2, hypoxia, acidosis, ROS, Hsp and protective autophagy, have been shown to induce anoikis resistance in glioma. In our present review, we aim to summarize the underlying mechanism of resistance and the therapeutic potential of these molecules.

Dysregulation of Cytoskeleton Remodeling Drives Invasive Leading Cells Detachment

Simple Summary

Detachment of cancer cells is the first step in tumor metastasis and malignancy. Our results showed that the TGF-β1/vimentin/focal adhesion protein assembly axis was involved in the control of the dynamics of initial tumor detachment under adequate nutrition, based on the Boyden chamber and 3D in-gel spheroid analysis.

Abstract

Detachment of cancer cells is the first step in tumor metastasis and malignancy. However, studies on the balance of initial tumor anchoring and detachment are limited. Herein, we revealed that the regulation of cytoskeleton proteins potentiates tumor detachment. The blockage of TGF-β1 using neutralizing antibodies induced cancer cell detachment in the Boyden chamber and 3D in-gel spheroid models. Moreover, treatment with latrunculin B, an actin polymerization inhibitor, enhanced cell dissociation by abolishing actin fibers, indicating that TGF-β1 mediates the formation of actin stress fibers, and is likely responsible for the dynamics of anchoring and detachment. Indeed, latrunculin B disrupted the formation of external TGF-β1-induced actin fibers and translocation of intracellular vinculin, a focal adhesion protein, resulting in the suppression of cell adhesion. Moreover, the silencing of vimentin substantially reduced cell adhesion and enhanced cell detachment, revealing that cell adhesion and focal adhesion protein translocation stimulated by TGF-β1 require vimentin. Using the 3D in-gel spheroid model, we found that latrunculin B suppressed the cell adhesion promoted by external TGF-β1, increasing the number of cells that penetrated the Matrigel and detached from the tumor spheres. Thus, cytoskeleton remodeling maintained the balance of cell anchoring and detachment, and the TGF-β1/vimentin/focal adhesion protein assembly axis was involved in the control dynamics of initial tumor detachment.

TRIM50 Suppresses Pancreatic Cancer Progression and Reverses the Epithelial-Mesenchymal Transition via Facilitating the Ubiquitous Degradation of Snail1

Emerging evidence suggests that the tripartite motif (TRIM) family play important roles in tumor development and progression. Tripartite motif-containing 50 (TRIM50) is a member of the TRIM family, but little is known regarding its expression and potential functional roles in cancer. In this study, we first analyzed the expression pattern and clinical significance of TRIM50 in pancreatic cancer and found that TRIM50 expression is significantly reduced in pancreatic cancer tissues and its downregulation is associated with poor survival for pancreatic cancer patients. Functionally, TRIM50 overexpression in pancreatic cancer cells decreases their proliferation and motility capabilities and reverses the epithelial-mesenchymal transition (EMT) process, whereas TRIM50 depletion had the opposite effects. Mechanically, TRIM50 directly interacts with Snail1, a key regulator of EMT, and acts as an E3 ubiquitin ligase to target Snail1 for ubiquitous degradation. The function of TRIM50 in suppressing cell migration and EMT depends on TRIM50-promoted Snail1 degradation. In conclusion, our findings identify TRIM50 as a tumor suppressor that inhibits pancreatic cancer progression and reverses EMT via degrading Snail1 and provide new insights into the progression of pancreatic cancer.

Epithelial plasticity, epithelial-mesenchymal transition, and the TGF-β family

Epithelial cells repress epithelial characteristics and elaborate mesenchymal characteristics to migrate to other locations and acquire new properties. Epithelial plasticity responses are directed through cooperation of signaling pathways, with TGF-β and TGF-β-related proteins playing prominent instructive roles. Epithelial-mesenchymal transitions (EMTs) directed by activin-like molecules, bone morphogenetic proteins, or TGF-β regulate metazoan development and wound healing and drive fibrosis and cancer progression. In carcinomas, diverse EMTs enable stem cell generation, anti-cancer drug resistance, genomic instability, and localized immunosuppression. This review discusses roles of TGF-β and TGF-β-related proteins, and underlying molecular mechanisms, in epithelial plasticity in development and wound healing, fibrosis, and cancer.

The Role of TGF-β Signaling Pathways in Cancer and Its Potential as a Therapeutic Target

The transforming growth factor-β (TGF-β) signaling pathway mediates various biological functions, and its dysregulation is closely related to the occurrence of malignant tumors. However, the role of TGF-β signaling in tumorigenesis and development is complex and contradictory. On the one hand, TGF-β signaling can exert antitumor effects by inhibiting proliferation or inducing apoptosis of cancer cells. On the other hand, TGF-β signaling may mediate oncogene effects by promoting metastasis, angiogenesis, and immune escape. This review summarizes the recent findings on molecular mechanisms of TGF-β signaling. Specifically, this review evaluates TGF-β's therapeutic potential as a target by the following perspectives: ligands, receptors, and downstream signaling. We hope this review can trigger new ideas to improve the current clinical strategies to treat tumors related to the TGF-β signaling pathway.

The translational values of TRIM family in pan-cancers: From functions and mechanisms to clinics

Cancer is the second leading cause of human death across the world. Tripartite motif (TRIM) family, with E3 ubiquitin ligase activities in majority of its members, is reported to be involved in multiple cellular processes and signaling pathways. TRIM proteins have critical effects in the regulation of biological behaviors of cancer cells. Here, we discussed the current understanding of the molecular mechanism of TRIM proteins regulation of cancer cells. We also comprehensively reviewed published studies on TRIM family members as oncogenes or tumor suppressors in the oncogenesis, development, and progression of a variety of types of human cancers. Finally, we highlighted that certain TRIM family members are potential molecular biomarkers for cancer diagnosis and prognosis, and potential therapeutic targets.

Ubiquitin Ligases at the Heart of Skeletal Muscle Atrophy Control

Skeletal muscle loss is a detrimental side-effect of numerous chronic diseases that dramatically increases mortality and morbidity. The alteration of protein homeostasis is generally due to increased protein breakdown while, protein synthesis may also be down-regulated. The ubiquitin proteasome system (UPS) is a master regulator of skeletal muscle that impacts muscle contractile properties and metabolism through multiple levers like signaling pathways, contractile apparatus degradation, etc. Among the different actors of the UPS, the E3 ubiquitin ligases specifically target key proteins for either degradation or activity modulation, thus controlling both pro-anabolic or pro-catabolic factors. The atrogenes MuRF1/TRIM63 and MAFbx/Atrogin-1 encode for key E3 ligases that target contractile proteins and key actors of protein synthesis respectively. However, several other E3 ligases are involved upstream in the atrophy program, from signal transduction control to modulation of energy balance. Controlling E3 ligases activity is thus a tempting approach for preserving muscle mass. While indirect modulation of E3 ligases may prove beneficial in some situations of muscle atrophy, some drugs directly inhibiting their activity have started to appear. This review summarizes the main signaling pathways involved in muscle atrophy and the E3 ligases implicated, but also the molecules potentially usable for future therapies.

E3 Ubiquitin Ligases: Key Regulators of TGFβ Signaling in Cancer Progression

Transforming growth factor β (TGFβ) is a secreted growth and differentiation factor that influences vital cellular processes like proliferation, adhesion, motility, and apoptosis. Regulation of the TGFβ signaling pathway is of key importance to maintain tissue homeostasis. Perturbation of this signaling pathway has been implicated in a plethora of diseases, including cancer. The effect of TGFβ is dependent on cellular context, and TGFβ can perform both anti- and pro-oncogenic roles. TGFβ acts by binding to specific cell surface TGFβ type I and type II transmembrane receptors that are endowed with serine/threonine kinase activity. Upon ligand-induced receptor phosphorylation, SMAD proteins and other intracellular effectors become activated and mediate biological responses. The levels, localization, and function of TGFβ signaling mediators, regulators, and effectors are highly dynamic and regulated by a myriad of post-translational modifications. One such crucial modification is ubiquitination. The ubiquitin modification is also a mechanism by which crosstalk with other signaling pathways is achieved. Crucial effector components of the ubiquitination cascade include the very diverse family of E3 ubiquitin ligases. This review summarizes the diverse roles of E3 ligases that act on TGFβ receptor and intracellular signaling components. E3 ligases regulate TGFβ signaling both positively and negatively by regulating degradation of receptors and various signaling intermediates. We also highlight the function of E3 ligases in connection with TGFβ's dual role during tumorigenesis. We conclude with a perspective on the emerging possibility of defining E3 ligases as drug targets and how they may be used to selectively target TGFβ-induced pro-oncogenic responses.

Regulation of Epithelial-Mesenchymal Plasticity by the E3 Ubiquitin-Ligases in Cancer

The epithelial-mesenchymal plasticity (EMP) is a process by which epithelial cells acquire the ability to dynamically switch between epithelial and mesenchymal phenotypic cellular states. Epithelial cell plasticity in the context of an epithelial-to-mesenchymal transition (EMT) confers increased cell motility, invasiveness and the ability to disseminate to distant sites and form metastasis. The modulation of molecularly defined targets involved in this process has become an attractive therapeutic strategy against cancer. Protein degradation carried out by ubiquitination has gained attention as it can selectively degrade proteins of interest. In the ubiquitination reaction, the E3 ubiquitin-ligases are responsible for the specific binding of ubiquitin to a small subset of target proteins, and are considered promising anticancer drug targets. In this review, we summarize the role of the E3 ubiquitin-ligases that control targeted protein degradation in cancer-EMT, and we highlight the potential use of the E3 ubiquitin-ligases as drug targets for the development of small-molecule drugs against cancer.

A Regulatory Axis of circ_0008193/miR-1180-3p/TRIM62 Suppresses Proliferation, Migration, Invasion, and Warburg Effect in Lung Adenocarcinoma Cells Under Hypoxia

BACKGROUND Expression profiles of circular ribonucleic acids (circRNAs) have been recently reported in lung cancers including lung adenocarcinoma (LUAD). Hypoxia is a hallmark of lung cancers. However, the role of hsa_circ_0008193 (circ_0008193) in LUAD under hypoxia remains to be illuminated. MATERIAL AND METHODS Gene expression levels were detected using real-time quantitative polymerase chain reaction and western blotting. Cell proliferation, migration, invasion, and Warburg effect were detected using 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyltetrazolium bromide assay, transwell assays, special kits, and xenograft experiments. The relationship among circ_0008193, micro (mi)RNA (miR)-1180-3p, and tripartite motif containing 62 (TRIM62) was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation. RESULTS Expression of circ_0008193 was downregulated in human LUAD tumor tissues and cell lines (A549 and H1975), accompanied by miR-1180-3p upregulation and TRIM62 downregulation. Moreover, circ_0008193 downregulation was correlated with tumor size and lymph node metastasis. Functionally, circ_0008193 overexpression inhibited cell viability, glucose uptake, lactate production, migration, and invasion, as well as expression of hexokinase II, lactate dehydrogenase A, matrix metalloproteinase 2 (MMP2), and MMP9 in hypoxic LUAD cells in vitro. Furthermore, tumor growth of A549 cells in vivo was also hindered by circ_0008193 overexpression. Mechanically, circ_0008193 regulated TRIM62 expression via sponging miR-1180-3p, and TRIM62 was targeted by miR-1180-3p. Both miR-1180-3p upregulation and TRIM62 downregulation could abolish the suppressive role of circ_0008193 in LUAD cells. CONCLUSIONS Upregulating circ_0008193 inhibited LUAD cell proliferation, migration, invasion, and Warburg effect under hypoxia in vitro and in vivo through regulation of the miR-1180-3p/TRIM62 axis.

Association of DEAR1 Tagging Single Nucleotide Polymorphisms With Breast Cancer in a Sample of Colombian Population: A Case Control Study

Purpose:

Ubiquitin ligase genes can act as oncogenes or tumor suppressor genes. They play a role in various diseases, including development and progression of breast cancer; the objective of this study was to evaluate the association of common variants in the ductal-epithelium-associated RING chromosome 1 (DEAR1) gene with breast cancer risk in a sample of Colombian population.

Methods:

We carried out a case-control study to investigate associations of variants in DEAR1 with breast cancer in women from Colombia. Single nucleotide polymorphisms (SNPs) rs584298, rs2927970, rs59983645, and rs599167 were genotyped in 1022 breast cancer cases and 1023 healthy controls using the iPLEX® and Kompetitive Allele Specific PCR (polymerase chain reaction) (KASP) method. The associations between SNPs and breast cancer were examined by conditional logistic regression. The associations between SNPs and epidemiological/histopathological variables were examined by multinomial logistic regression.

Results:

Associations were found between tag SNPs and breast cancer adjusted for the epidemiological risk factors rs584298 genotypes AG and GG (P = .048 and P = .004, respectively). The analysis of the disease characteristics showed that SNP rs584298 (genotype AG) (P = .015) shows association with progesterone receptor (PR) status and (genotype AA) (P = .048) shows association with human epidermal growth factor receptor 2 (HER2) status.

Conclusions:

The SNP rs584298 in DEAR1 showed associations with breast cancer and the expression of HER2 receptor; when this receptor is amplified, the result is aggressive tumoral subtype and expression of PR receptor that is associated with high-proliferative tumor grade. Validation of this SNP is important to establish whether this variant or the tagged variant is the cause for the risk association showed.

Novel Semi-Replicative Retroviral Vector Mediated Double Suicide Gene Transfer Enhances Antitumor Effects in Patient-Derived Glioblastoma Models

As glioblastomas are mostly localized infiltrative lesions, gene therapy based on the retroviral replicating vector (RRV) system is considered an attractive strategy. Combinations of multiple suicide genes can circumvent the limitations associated with each gene, achieving direct and synergistic cytotoxic effects, along with bystander cell killing. In this study, we constructed a semi-and pseudotyped-RRV (sp-RRV) system harboring two suicide genes—herpes simplex virus type 1 thymidine kinase (TK) and yeast cytosine deaminase (CD)—to verify the dissemination and antitumor efficacy of our sp-RRV system (spRRVe-sEF1α-TK/sRRVgp-sEF1α-CD) in seven patient-derived glioblastoma stem-like cells (GSCs). Flow cytometry and high-content analysis revealed a wide range of transduction efficiency and good correlation between the delivery of therapeutic genes and susceptibility to the prodrugs ganciclovir and 5-fluorocytosine in patient-derived GSCs in vitro. Intra-tumoral delivery of spRRVe-sEF1α-TK/sRRVgp-sEF1α-CD, combined with prodrug treatment, synergistically inhibited cell proliferation and angiogenesis while increasing apoptosis and the depletion of tumor-associated macrophages in orthotopic glioblastoma xenografts. Genomic profiling of patient-derived GSCs revealed that the key genes preventing sp-RRV infection and transmission were associated with cell adhesion, migration, development, differentiation, and proliferation. This is the first report demonstrating that a novel sp-RRV-mediated TK/CD double suicide gene transfer system has high oncolytic power against extremely heterogeneous and treatment-refractory glioblastomas.

The Role of Tripartite Motif Family Proteins in TGF-β Signaling Pathway and Cancer

TGF-β signaling plays a tumor suppressive role in normal and premalignant cells but promotes tumor progression during the late stages of tumor development. The TGF-β signaling pathway is tightly regulated at various levels, including transcriptional and post-translational mechanisms. Ubiquitination of signaling components, such as receptors and Smad proteins is one of the key regulatory mechanisms of TGF-β signaling. Tripartite motif (TRIM) family of proteins is a highly conserved group of E3 ubiquitin ligase proteins that have been implicated in a variety of cellular functions, including cell growth, differentiation, immune response, and carcinogenesis. Recent emerging studies have shown that some TRIM family proteins function as important regulators in tumor initiation and progression. This review summarizes current knowledge of TRIM family proteins regulating the TGF-β signaling pathway with relevance to cancer.

lncRNA DRHC inhibits proliferation and invasion in hepatocellular carcinoma via c-Myb-regulated MEK/ERK signaling

Accumulating evidence indicates that long non-coding RNAs (lncRNAs) play a crucial role in hepatocellular carcinoma (HCC). Here, we reported a novel lncRNA, CTC-505O3 (lncRNA DRHC), that was downregulated in HCC and its low expression was associated with dismal survival. Gain-of-function studies indicated that it inhibited proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) in HCC cell lines in vitro. lncRNA DRHC also inhibited tumorigenicity in vivo. In mechanistic experiments, GO analysis based on NGS indicated that MAPK signaling was most affected. The result was confirmed by Western blot and this effect was abolished either by MEK1/2 specific inhibitor Trametinib or ERK1/2 inhibitor SCH772984. In addition, differences in proliferation and invasion were abrogated by Trametinib. Moreover, we found that lncRNA DRHC interacted with MYBBP1A and modulated MEK/ERK signaling via c-Myb. Taken together, our findings indicate that the lncRNA DRHC play a key role in HCC progression and may serve as a novel therapeutic target.

Inhibin B suppresses anoikis resistance and migration through the transforming growth factor-β signaling pathway in nasopharyngeal carcinoma

Inhibin B (INHBB), a heterodimer of a common α‐subunit and a βB‐subunit, is a glycoprotein belonging to the transforming growth factor‐β (TGF‐β) family. In this study, we observed INHBB expression was reduced in nasopharyngeal carcinoma (NPC) tissues compared to non‐tumor nasopharyngeal epithelium tissues, and INHBB was associated with lymph node metastasis, stage of disease, and clinical progress. Positive expression of INHBB in NPC predicted a better prognosis (overall survival, P = 0.038). However, the molecular mechanisms of INHBB have not been addressed in NPC. We induced anoikis‐resistant cells in NPC cell lines under anchorage‐independent conditions, then found epithelial‐mesenchymal transition markers changed, cell apoptosis decreased, cell cycle was modified, and invasion strengthened in anoikis‐resistant NPC cells. These anoikis‐resistant NPC cells showed decreased expression of INHBB compared with adhesion cells. Furthermore, INHBB was found to influence the above‐mentioned changes. In the anoikis‐resistant NPC cells with INHBB overexpression, apoptotic cells increased, S phase cells weakened, vimentin, matrix metallopeptidase‐9, and vascular endothelial growth factor A expression were downregulated, and E‐cadherin expression was upregulated, and vice versa in knockdown of INHBB (INHBB shRNA) anoikis‐resistant NPC cells. Diminished INHBB expression could activate the TGF‐β pathway to phosphorylate Smad2/3 and form complexes in the nucleus, which resulted in the above changes. Thus, our results revealed for the first time that INHBB could suppress anoikis resistance and migration of NPC cells by the TGF‐β signaling pathway, decrease p53 overexpression, and could serve as a potential biomarker for NPC metastasis and prognosis as well as a therapeutic application.

TGF-β induced epithelial-mesenchymal transition in an advanced cervical tumor model by 3D printing

An advanced in vitro cervical tumor model was established by 3D printing to study the epithelial-to-mesenchymal transition (EMT), which is a very important stage of dissemination of carcinoma leading to metastatic tumors. A HeLa/hydrogel grid construct composed of gelatin, alginate, Matrigel and HeLa cells was fabricated by forced extrusion in a layer-by-layer fashion. HeLa cells rapidly proliferated, formed spheroids and presented tumorigenic characteristic in the 3D-printed structure. With the supplement of TGF-β, aggregated HeLa cells started to disintegrate, and some of them changed into fibroblast-like spindle morphology, which indicated that EMT was induced. The down-regulation of epithelial marker E-cadherin, and up-regulation of mesenchymal markers such as snail, vimentin and N-cadherin were all observed in the 3D-printed model, and performed differently in 3D and 2D models. The TGF-β induced EMT was inhibited by the treatment of disulfiram and EMT pathway inhibitor C19 in a dose dependent manner, showing great potential for future studies of a therapeutic program towards cervical tumor metastasis.

Identification of genetic variants predictive of early onset pancreatic cancer through a population science analysis of functional genomic datasets

Biomarkers are critically needed for the early detection of pancreatic cancer (PC) are urgently needed. Our purpose was to identify a panel of genetic variants that, combined, can predict increased risk for early-onset PC and thereby identify individuals who should begin screening at an early age. Previously, we identified genes using a functional genomic approach that were aberrantly expressed in early pathways to PC tumorigenesis. We now report the discovery of single nucleotide polymorphisms (SNPs) in these genes associated with early age at diagnosis of PC using a two-phase study design. In silico and bioinformatics tools were used to examine functional relevance of the identified SNPs. Eight SNPs were consistently associated with age at diagnosis in the discovery phase, validation phase and pooled analysis. Further analysis of the joint effects of these 8 SNPs showed that, compared to participants carrying none of these unfavorable genotypes (median age at PC diagnosis 70 years), those carrying 1–2, 3–4, or 5 or more unfavorable genotypes had median ages at diagnosis of 64, 63, and 62 years, respectively (P = 3.0E–04). A gene-dosage effect was observed, with age at diagnosis inversely related to number of unfavorable genotypes (P_trend = 1.0E–04). Using bioinformatics tools, we found that all of the 8 SNPs were predicted to play functional roles in the disruption of transcription factor and/or enhancer binding sites and most of them were expression quantitative trait loci (eQTL) of the target genes. The panel of genetic markers identified may serve as susceptibility markers for earlier PC diagnosis.

Molecular insights into tumour metastasis: tracing the dominant events

Metastasis of malignant cells to vital organs remains the major cause of mortality in many types of cancers. The tumour invasion-metastasis cascade is a stepwise and multistage process whereby tumour cells disseminate from primary sites and spread to colonize distant sites through the systemic haematogenous or lymphatic circulations. The general steps of metastasis may be similar in almost all tumour types, but metastasis to different tissues seems to require distinct sets of regulators and/or an 'educated' microenvironment which may facilitate the infiltration and colonization of tumour cells to specific tissues. Moreover, interactions of tumour cells with stromal cells, endothelial cells, and immune cells that they encounter will also aid them to gain survival advantages, evade immune surveillance, and adapt to the new host microenvironment. Due to the high correlation between tumour metastasis and survival rate of patients, a deeper understanding of the molecular participants and processes involved in metastasis could pave the way towards novel, more effective and targeted approaches to prevent and treat tumour metastasis. In this review, we provide an update on the regulation networks orchestrated by the dominant regulators of different stages throughout the metastatic process including, but not limited to, epithelial-mesenchymal transition in local invasion, resistance to anoikis during migration, and colonization of different distant sites. We also put forward some suggestions and problems concerning the treatment of tumour metastasis that should be solved and/or improved for better therapies in the near future. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

TGFΒ-induced transcription in cancer

The Transforming Growth Factor-beta (TGFβ) pathway mediates a broad spectrum of cellular processes and is involved in several diseases, including cancer. TGFβ has a dual role in tumours, acting as a tumour suppressor in the early phase of tumorigenesis and as a tumour promoter in more advanced stages. In this review, we discuss the effects of TGFβ-driven transcription on all stages of tumour progression, with special focus on lung cancer. Since some TGFβ target genes are specifically involved in promoting metastasis, we speculate that these genes might be good targets to block tumour progression without compromising the tumour suppressor effects of the TGFβ pathway.

Bcl-3 regulates TGFβ signaling by stabilizing Smad3 during breast cancer pulmonary metastasis

Transforming growth factor beta (TGFβ) signaling in breast cancer is selectively associated with pulmonary metastasis. However, the underlying mechanisms remain unclear. Here we show that Bcl-3, a member of the IκB family, serves as a critical regulator in TGFβ signaling to modulate breast cancer pulmonary metastasis. Bcl-3 expression was significantly associated with metastasis-free survival in breast cancer patients. Bcl-3 deletion inhibited the migration and invasion of breast cancer cells in vitro, as well as breast cancer lung metastasis in vivo. Bcl-3 was required for the expression of downstream TGFβ signaling genes that are involved in breast cancer lung metastasis. Bcl-3 knockdown enhanced the degradation of Smad3 but not Smad2 following TGFβ treatment. Bcl-3 could bind to Smad3 and prevent the ubiquitination and degradation of Smad3 protein. These results indicate that Bcl-3 serves as a promising target to prevent breast tumor lung metastasis.

Tripartite motif containing 62 is a novel prognostic marker and suppresses tumor metastasis via c-Jun/Slug signaling-mediated epithelial-mesenchymal transition in cervical cancer

Background

TRIM62 (tripartite motif containing 62) has been found to act as a tumor suppressor of several cancers. However, its precise biological role and related mechanism remain unknown in cervical cancer (CC).

Methods

Quantitative Real-time PCR and western blot were adopted to detect the mRNA and protein expression level of TRIM62 in both human CC cell lines and tissues. Immunohistochemistry was used to measure the TRIM62 expression in 30 normal cervical and 189 CC tissues. Univariate and multivariate Cox regression analyses and Kaplan–Meier survival analyses performed to investigate the association between TRIM62 expression and CC patients’ prognosis. The effect of TRIM62 on CC growth and metastasis was studied in vitro and in vivo. Multi-pathway reporter array were utilized to identify the potential signaling manipulated by TRIM62.

Results

TRIM62 was frequently down-regulated in both human CC cells and tissues. Low expression of TRIM62 in CC tissues was associated with aggressive clinicopathological features of CC patients. In addition, TRIM62 was also an independent poor prognostic factor for overall and disease-free survival of CC patients after surgery. Moreover, enforced expression of TRIM62 in CC cells significantly inhibited their abilities of proliferation, migration and invasion in vitro. Besides, subcutaneous xenograft tumor model and xenograft mouse metastatic model respectively displayed that TRIM62 impeded the growth and metastasis of CC in vivo. Furthermore, mechanism study exhibited that TRIM62 could suppress epithelial-mesenchymal transition (EMT) by inhibiting c-Jun/Slug signaling. The inhibitory role of TRIM62 in tumor proliferation might be through regulating cell cycle related proteins CyclinD1 and P27 by targeting c-Jun.

Conclusion

TRIM62 is a potential prognostic biomarker in CC and suppresses metastasis of CC via inhibiting c-Jun/Slug signaling-mediated EMT.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0445-5) contains supplementary material, which is available to authorized users.

Negative regulation of the innate antiviral immune response by TRIM62 from orange spotted grouper

Increased reports uncovered that mammalian tripartite motif-containing 62 (TRIM62) exerts crucial roles in cancer and innate immune response. However, the roles of fish TRIM62 in antiviral immune response remained uncertain. In this study, a TRIM62 gene was cloned from orange spotted grouper (EcTRIM62) and its roles in grouper RNA virus infection was elucidated in vitro. EcTRIM62 shared 99% and 83% identity to bicolor damselfish (Stegastes partitus) and human (Homo sapiens), respectively. Sequence alignment indicated that EcTRIM62 contained three domains, including a RING-finger domain, a B-box domain and a SPRY domain. In healthy grouper, the transcript of EcTRIM62 was predominantly detected in brain and liver, followed by heart, skin, spleen, fin, gill, intestine, and stomach. Subcellular localization analysis indicated that bright fluorescence spots were observed in the cytoplasm of EcTRIM62-transfected grouper spleen (GS) cells. During red-spotted grouper nervous necrosis (RGNNV) infection, overexpression of EcTRIM62 significantly enhanced the severity of CPE and increased viral gene transcriptions. Furthermore, the ectopic expression of EcTRIM62 significantly decreased the transcription level of interferon signaling molecules, including interferon regulatory factor 3 (IRF3), IRF7, interferon-stimulated gene 15 (ISG15), melanoma differentiation-associated protein 5 (MDA5), myxovirus resistance gene MXI, and MXII, suggesting that the negative regulation of interferon immune response by EcTRIM62 might directly contributed to its enhancing effect on RGNNV replication. Furthermore, our results also demonstrated that overexpression of EcTRIM62 was able to differently regulate the expression levels of pro-inflammation cytokines. In addition, we found the ectopic expression of EcTIRM62 negatively regulated MDA5-, but not mediator of IRF3 activation (MITA)-induced interferon immune response. Further studies showed that the deletion of RING domain and SPRY domain significantly affected the action of EcTRIM62, including the enhancing effect on virus replication and regulation of interferon immune response. Thus, our studies firstly demonstrated that EcTRIM62 negatively regulated the innate antiviral immune response against fish RNA viruses.

Mechanisms of TGFβ-Induced Epithelial-Mesenchymal Transition

Transitory phenotypic changes such as the epithelial–mesenchymal transition (EMT) help embryonic cells to generate migratory descendants that populate new sites and establish the distinct tissues in the developing embryo. The mesenchymal descendants of diverse epithelia also participate in the wound healing response of adult tissues, and facilitate the progression of cancer. EMT can be induced by several extracellular cues in the microenvironment of a given epithelial tissue. One such cue, transforming growth factor β (TGFβ), prominently induces EMT via a group of specific transcription factors. The potency of TGFβ is partly based on its ability to perform two parallel molecular functions, i.e. to induce the expression of growth factors, cytokines and chemokines, which sequentially and in a complementary manner help to establish and maintain the EMT, and to mediate signaling crosstalk with other developmental signaling pathways, thus promoting changes in cell differentiation. The molecules that are activated by TGFβ signaling or act as cooperating partners of this pathway are impossible to exhaust within a single coherent and contemporary report. Here, we present selected examples to illustrate the key principles of the circuits that control EMT under the influence of TGFβ.

Elf5 inhibits TGF-β-driven epithelial-mesenchymal transition in prostate cancer by repressing SMAD3 activation

BACKGROUND

The epithelial-mesenchymal transition (EMT) has been associated with the acquisition of migration, invasiveness, and metastasis traits. During tumor progression, EMT can be induced by transforming growth factor-β (TGF-β) signal that epithelial cells receive from their microenvironment. However, the master regulatory controls on TGF-β-EMT axis are not understood.

METHODS

The protein expression in human specimens was measured by immunohistochemical staining. E74-like factor 5 (Elf5) was silenced by short interfering RNAs in LNCaP cells and stably overexpressed by HA-tagged Elf5 cDNAs in 22Rv1 cells. These cells were used to study migration and anchorage-independent growth.

RESULTS

Our data reveal that Elf5 results in the failure of mesenchymal morphogenesis, upregulation of EMT markers, spheres formation, and migration in the presence of TGF-β. Furthermore, Elf5 blocks TGF-β signaling, through decreasing drosophila mothers against decapentaplegic protein (SMAD3) activation by binding to it, one of the major effector of TGF-β-induced EMT. Moreover, Elf5 can serve as a prognostic marker of metastasis-free survival in patients with TGF-β-positive prostate cancer.

CONCLUSIONS

Elf5 expression is inversely correlated with EMT. Elf5 inhibits TGF-β-driven EMT via repressing SMAD3 phosphorylation in prostate cancer cells. In addition, Elf5 can be used as a biomarker of metastasis-free survival in patients with TGF-β-positive prostate cancer.

Galanin modulates the neural niche to favour perineural invasion in head and neck cancer

Perineural invasion (PNI) is an indicator of poor survival in multiple cancers. Unfortunately, there is no targeted treatment for PNI since the molecular mechanisms are largely unknown. PNI is an active process, suggesting that cancer cells communicate with nerves. However, nerve-tumour crosstalk is understudied due to the lack of in vivo models to investigate the mechanisms. Here, we developed an in vivo model of PNI to characterise this interaction. We show that the neuropeptide galanin (GAL) initiates nerve-tumour crosstalk via activation of its G-protein-coupled receptor, GALR2. Our data reveal a novel mechanism by which GAL from nerves stimulates GALR2 on cancer cells to induce NFATC2-mediated transcription of cyclooxygenase-2 and GAL. Prostaglandin E2 promotes cancer invasion, and in a feedback mechanism, GAL released by cancer induces neuritogenesis, facilitating PNI. This study describes a novel in vivo model for PNI and reveals the dynamic interaction between nerve and cancer.

DEAR1, a novel tumor suppressor that regulates cell polarity and epithelial plasticity

Elucidation of the regulatory controls on epithelial plasticity is pivotal not only to better understand the nature of metastasis but also for the design of targeted therapies to prevent the earliest steps in migration and invasion from the primary tumor. This review will highlight the role of the novel TRIM protein DEAR1 (annotated as TRIM62) in the regulation of apical-basal polarity and acinar morphogenesis as well as its function as a chromosome 1p35 tumor suppressor and negative regulator of TGFβ-driven epithelial-mesenchymal transition (EMT). DEAR1 binds to and promotes the ubiquitination of SMAD3, the major effector of TGFβ-mediated EMT, as well as downregulates SMAD3 targets SNAIL1/2, master transcriptional regulators of EMT. Cumulative results suggest a novel paradigm for DEAR1 in the regulation of the breast tumor microenvironment, polarity, and EMT. Because DEAR1 undergoes loss-of-function mutations, homozygous deletion, as well as copy-number losses in multiple epithelial cancers, including breast cancer, DEAR1 has clinical use as a predictive and prognostic biomarker as well as for stratifying breast cancers and potentially other epithelial tumor types for targeted therapies aimed at the pathways regulated by DEAR1.

Cancer cell survival during detachment from the ECM: multiple barriers to tumour progression

Epithelial cells require attachment to the extracellular matrix (ECM) for survival. However, during tumour progression and metastasis, cancerous epithelial cells must adapt to and survive in the absence of ECM. During the past 20 years, several cellular changes, including anoikis, have been shown to regulate cell viability when cells become detached from the ECM. In this Opinion article, we review in detail how cancer cells can overcome or take advantage of these specific processes. Gaining a better understanding of how cancer cells survive during detachment from the ECM will be instrumental in designing chemotherapeutic strategies that aim to eliminate ECM-detached metastatic cells.

Loss of the novel tumour suppressor and polarity gene Trim62 (Dear1) synergizes with oncogenic Ras in invasive lung cancer

Deregulation of cell polarity proteins has been linked to the processes of invasion and metastasis. TRIM62 is a regulator of cell polarity and a tumour suppressor in breast cancer. Here, we demonstrate that human non-small cell lung cancer lesions show a step-wise loss of TRIM62 levels during disease progression, which was associated with poor clinical outcomes. To directly examine the role of Trim62 in development of lung cancer, we deleted Trim62 in a mutant K-Ras mouse model of lung cancer. In this context, haploinsufficiency of Trim62 synergized with a K-RasG12D mutation to promote invasiveness and disrupt three-dimensional morphogenesis, both of which are associated with epithelial-mesenchymal transitions. Re-expression of Trim62 reverted these phenotypes in tumour cell lines. Thus, Trim62 loss cooperates with K-Ras mutation in tumourigenesis and metastasis in vivo, indicating that decreased levels of TRIM62 may play an important role in the evolution of lung cancer.

TGFβ and matrix-regulated epithelial to mesenchymal transition

BACKGROUND

The progression of cancer through stages that guide a benign hyperplastic epithelial tissue towards a fully malignant and metastatic carcinoma, is driven by genetic and microenvironmental factors that remodel the tissue architecture. The concept of epithelial-mesenchymal transition (EMT) has evolved to emphasize the importance of plastic changes in tissue architecture, and the cross-communication of tumor cells with various cells in the stroma and with specific molecules in the extracellular matrix (ECM).

SCOPE OF THE REVIEW

Among the multitude of ECM-embedded cytokines and the regulatory potential of ECM molecules, this article focuses on the cytokine transforming growth factor β (TGFβ) and the glycosaminoglycan hyaluronan, and their roles in cancer biology and EMT. For brevity, we concentrate our effort on breast cancer.

MAJOR CONCLUSIONS

Both normal and abnormal TGFβ signaling can be detected in carcinoma and stromal cells, and TGFβ-induced EMT requires the expression of hyaluronan synthase 2 (HAS2). Correspondingly, hyaluronan is a major constituent of tumor ECM and aberrant levels of both hyaluronan and TGFβ are thought to promote a wounding reaction to the local tissue homeostasis. The link between EMT and metastasis also involves the mesenchymal-epithelial transition (MET). ECM components, signaling networks, regulatory non-coding RNAs and epigenetic mechanisms form the network of regulation during EMT-MET.

GENERAL SIGNIFICANCE

Understanding the mechanism that controls epithelial plasticity in the mammary gland promises the development of valuable biomarkers for the prognosis of breast cancer progression and even provides new ideas for a more integrative therapeutic approach against disease. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.