Regulation of epithelial-mesenchymal transition through SUMOylation of transcription factors

N6-methyladenosine modification and post-translational modification of epithelial-mesenchymal transition in colorectal cancer

Colorectal cancer is a leading cause of cancer-related mortality worldwide. Traditionally, colorectal cancer has been recognized as a disease caused by genetic mutations. However, recent studies have revealed the significant role of epigenetic alterations in the progression of colorectal cancer. Epithelial-mesenchymal transition, a critical step in cancer cell metastasis, has been found to be closely associated with the tumor microenvironment and immune factors, thereby playing a crucial role in many kinds of biological behaviors of cancers. In this review, we explored the impact of N6-methyladenosine and post-translational modifications (like methylation, acetylation, ubiquitination, SUMOylation, glycosylation, etc.) on the process of epithelial-mesenchymal transition in colorectal cancer and the epigenetic regulation for the transcription factors and pathways correlated to epithelial-mesenchymal transition. Furthermore, we emphasized that the complex regulation of epithelial-mesenchymal transition by epigenetics can provide new strategies for overcoming drug resistance and improving treatment outcomes. This review aims to provide important scientific evidence for the prevention and treatment of colorectal cancer based on epigenetic modifications.

Exploiting transcription factors to target EMT and cancer stem cells for tumor modulation and therapy

Transcription factors (TFs) are essential in controlling gene regulatory networks that determine cellular fate during embryogenesis and tumor development. TFs are the major players in promoting cancer stemness by regulating the function of cancer stem cells (CSCs). Understanding how TFs interact with their downstream targets for determining cell fate during embryogenesis and tumor development is a critical area of research. CSCs are increasingly recognized for their significance in tumorigenesis and patient prognosis, as they play a significant role in cancer initiation, progression, metastasis, and treatment resistance. However, traditional therapies have limited effectiveness in eliminating this subset of cells, allowing CSCs to persist and potentially form secondary tumors. Recent studies have revealed that cancer cells and tumors with CSC-like features also exhibit genes related to the epithelial-to-mesenchymal transition (EMT). EMT-associated transcription factors (EMT-TFs) like TWIST and Snail/Slug can upregulate EMT-related genes and reprogram cancer cells into a stem-like phenotype. Importantly, the regulation of EMT-TFs, particularly through post-translational modifications (PTMs), plays a significant role in cancer metastasis and the acquisition of stem cell-like features. PTMs, including phosphorylation, ubiquitination, and SUMOylation, can alter the stability, localization, and activity of EMT-TFs, thereby modulating their ability to drive EMT and stemness properties in cancer cells. Although targeting EMT-TFs holds potential in tackling CSCs, current pharmacological approaches to do so directly are unavailable. Therefore, this review aims to explore the role of EMT- and CSC-TFs, their connection and impact in cellular development and cancer, emphasizing the potential of TF networks as targets for therapeutic intervention.

ROS-mediated up-regulation of SAE1 by Helicobacter pylori promotes human gastric tumor genesis and progression

Helicobacter pylori (H. pylori) is a major risk factor of gastric cancer (GC). The SUMO-activating enzyme SAE1(SUMO-activating enzyme subunit 1), which is indispensable for protein SUMOylation, involves in human tumorigenesis. In this study, we used the TIMER and TCGA database to explore the SAE1 expression in GC and normal tissues and Kaplan-Meier Plotter platform for survival analysis of GC patients. GC tissue microarray and gastric samples from patients who underwent endoscopic treatment were employed to detect the SAE1expression. Our results showed that SAE1 was overexpressed in GC tissues and higher SAE1 expression was associated with worse clinical characteristics of GC patients. Cell and animal models showed that H. pylori infection upregulated SAE1, SUMO1, and SUMO2/3 protein expression. Functional assays suggested that suppression of SAE1 attenuated epithelial-mesenchymal transition (EMT) biomarkers and cell proliferation abilities induced by H. pylori. Cell and animal models of ROS inhibition in H. pylori showed that ROS could mediate the H. pylori-induced upregulation of SAE1, SUMO1, and SUMO2/3 protein. RNA sequencing was performed and suggested that knockdown of SAE1 could exert an impact on IGF-1 expression. General, increased SUMOylation modification is involved in H. pylori-induced GC.

Role of non-canonical post-translational modifications in gastrointestinal tumors

Post-translational modifications (PTMs) of proteins contribute to the occurrence and development of tumors. Previous studies have suggested that canonical PTMs such as ubiquitination, glycosylation, and phosphorylation are closely implicated in different aspects of gastrointestinal tumors. Recently, emerging evidence showed that non-canonical PTMs play an essential role in the carcinogenesis, metastasis and treatment of gastrointestinal tumors. Therefore, we summarized recent advances in sumoylation, neddylation, isoprenylation, succinylation and other non-canonical PTMs in gastrointestinal tumors, which comprehensively describe the mechanisms and functions of non-classical PTMs in gastrointestinal tumors. It is anticipated that targeting specific PTMs could benefit the treatment as well as improve the prognosis of gastrointestinal tumors.

Spindle Cell Carcinoma of the Head and Neck: Clinical Characteristics and Molecular Signatures

OBJECTIVE/HYPOTHESIS

Spindle cell carcinoma of the head and neck (HNSpCC) is a rare variant of head and neck squamous cell carcinoma (HNSCC). This study evaluated the clinical characteristics and molecular signatures of such tumors.

STUDY DESIGN

Retrospective analysis.

METHODS

Medical records of patients diagnosed with HNSpCC from 1996 to 2018 were reviewed. The clinicopathologic features, treatment modalities, and survival status were carefully recorded. Whole exome sequencing (WES) was performed to evaluate the genetic signatures of HNSpCC.

RESULTS

We found that among all 71 patients included in this study, the majority of them were male, with tumors developing predominantly in the oral cavity. The 1-, 3-, and 5-year disease-specific survival (DSS) rates were 64.6%, 49.5%, and 43.9%, respectively. A high local recurrence (LR) and distant metastasis (DM) rate (47.9%-25.3%, respectively) were observed. A significant proportion (28.2%) of patients with the worst prognosis had history of previous head and neck cancer (HNC) and had been treated with radiotherapy (RT). WES revealed that those post-RT SpCC shared common mutations with their previous HNC (pre-RT SCC), but gained additional genetic traits, such as hypoxia and cell-ECM interaction that were favorable for survival in an irradiated microenvironment. Distinct genetic landscapes in primary and post-RT SpCC were also found.

CONCLUSIONS

This study demonstrates that HNSpCC is a unique entity with more aggressive behavior than conventional HNSCC. HNSpCC arising from a previously irradiated field is a predictor of dismal survival. Both genetic and microenvironmental factors contribute to this highly invasive tumor.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:2183-2191, 2023.

Identification of the Transcriptional Regulatory Role of RUNX2 by Network Analysis in Lung Cancer Cells

The use of a new bioinformatics pipeline allowed the identification of deregulated transcription factors (TFs) coexpressed in lung cancer that could become biomarkers of tumor establishment and progression. A gene regulatory network (GRN) of lung cancer was created with the normalized gene expression levels of differentially expressed genes (DEGs) from the microarray dataset GSE19804. Moreover, coregulatory and transcriptional regulatory network (TRN) analyses were performed for the main regulators identified in the GRN analysis. The gene targets and binding motifs of all potentially implicated regulators were identified in the TRN and with multiple alignments of the TFs' target gene sequences. Six transcription factors (E2F3, FHL2, ETS1, KAT6B, TWIST1, and RUNX2) were identified in the GRN as essential regulators of gene expression in non-small-cell lung cancer (NSCLC) and related to the lung tumoral process. Our findings indicate that RUNX2 could be an important regulator of the lung cancer GRN through the formation of coregulatory complexes with other TFs related to the establishment and progression of lung cancer. Therefore, RUNX2 could become an essential biomarker for developing diagnostic tools and specific treatments against tumoral diseases in the lung after the experimental validation of its regulatory function.

Post-Translational Modification of ZEB Family Members in Cancer Progression

Post-translational modification (PTM), the essential regulatory mechanisms of proteins, play essential roles in physiological and pathological processes. In addition, PTM functions in tumour development and progression. Zinc finger E-box binding homeobox (ZEB) family homeodomain transcription factors, such as ZEB1 and ZEB2, play a pivotal role in tumour progression and metastasis by induction epithelial-mesenchymal transition (EMT), with activation of stem cell traits, immune evasion and epigenetic reprogramming. However, the relationship between ZEB family members' post-translational modification (PTM) and tumourigenesis remains largely unknown. Therefore, we focussed on the PTM of ZEBs and potential therapeutic approaches in cancer progression. This review provides an overview of the diverse functions of ZEBs in cancer and the mechanisms and therapeutic implications that target ZEB family members' PTMs.

The UBC9/SUMO pathway affects E-cadherin cleavage in HPV-positive head and neck cancer

Functional loss of E-cadherin is frequent during tumor progression and occurs through a variety of mechanisms, including proteolytic cleavage. E-cadherin downregulation leads to the conversion of a more malignant phenotype promoting Epithelial to Mesenchymal Transition (EMT). The UBC9/SUMO pathway has been also shown to be involved in the regulation of EMT in different cancers. Here we found an increased expression of UBC9 in the progression of Head and Neck Cancer (HNC) and uncovered a role for UBC9/SUMO in hampering the HPV-mediated E-cadherin cleavage in HNC.

Determination of WWOX Function in Modulating Cellular Pathways Activated by AP-2α and AP-2γ Transcription Factors in Bladder Cancer

Following the invention of high-throughput sequencing, cancer research focused on investigating disease-related alterations, often inadvertently omitting tumor heterogeneity. This research was intended to limit the impact of heterogeneity on conclusions related to WWOX/AP-2α/AP-2γ in bladder cancer which differently influenced carcinogenesis. The study examined the signaling pathways regulated by WWOX-dependent AP-2 targets in cell lines as biological replicates using high-throughput sequencing. RT-112, HT-1376 and CAL-29 cell lines were subjected to two stable lentiviral transductions. Following CAGE-seq and differential expression analysis, the most important genes were identified and functionally annotated. Western blot was performed to validate the selected observations. The role of genes in biological processes was assessed and networks were visualized. Ultimately, principal component analysis was performed. The studied genes were found to be implicated in MAPK, Wnt, Ras, PI3K-Akt or Rap1 signaling. Data from pathways were collected, explaining the differences/similarities between phenotypes. FGFR3, STAT6, EFNA1, GSK3B, PIK3CB and SOS1 were successfully validated at the protein level. Afterwards, a definitive network was built using 173 genes. Principal component analysis revealed that the various expression of these genes explains the phenotypes. In conclusion, the current study certified that the signaling pathways regulated by WWOX and AP-2α have more in common than that regulated by AP-2γ. This is because WWOX acts as an EMT inhibitor, AP-2γ as an EMT enhancer while AP-2α as a MET inducer. Therefore, the relevance of AP-2γ in targeted therapy is now more evident. Some of the differently regulated genes can find application in bladder cancer treatment.

Regulation of ZEB1 Function and Molecular Associations in Tumor Progression and Metastasis

Zinc finger E-box binding homeobox 1 (ZEB1) is a pleiotropic transcription factor frequently expressed in carcinomas. ZEB1 orchestrates the transcription of genes in the control of several key developmental processes and tumor metastasis via the epithelial-to-mesenchymal transition (EMT). The biological function of ZEB1 is regulated through pathways that influence its transcription and post-transcriptional mechanisms. Diverse signaling pathways converge to induce ZEB1 activity; however, only a few studies have focused on the molecular associations or functional changes of ZEB1 by post-translational modifications (PTMs). Due to the robust effect of ZEB1 as a transcription repressor of epithelial genes during EMT, the contribution of PTMs in the regulation of ZEB1-targeted gene expression is an active area of investigation. Herein, we review the pivotal roles that phosphorylation, acetylation, ubiquitination, sumoylation, and other modifications have in regulating the molecular associations and behavior of ZEB1. We also outline several questions regarding the PTM-mediated regulation of ZEB1 that remain unanswered. The areas of research covered in this review are contributing to new treatment strategies for cancer by improving our mechanistic understanding of ZEB1-mediated EMT.

SUMOylation and NEDDylation in Primary and Metastatic Cancers to Bone

Post-translational modifications comprise series of enzymatically-driven chemical modifications, virtually involving the entire cell proteome, that affect the fate of a target protein and, in turn, cell activity. Different classes of modifications can be established ranging from phosphorylation, glycosylation, ubiquitination, acetylation, methylation, lipidation and their inverse reactions. Among these, SUMOylation and NEDDylation are ubiquitin-like multi-enzymatic processes that determine the bound of SUMOs and NEDD8 labels, respectively, on defined amino acidic residues of a specific protein and regulate protein function. As fate-determinants of several effectors and mediators, SUMOylation and NEDDylation play relevant roles in many aspects of tumor cell biology. Bone represents a preferential site of metastasis for solid tumors (e.g., breast and prostate cancers) and the primary site of primitive tumors (e.g., osteosarcoma, chondrosarcoma). Deregulation of SUMOylation and NEDDylation affects different aspects of neoplastic transformation and evolution such as epithelial-mesenchymal transition, adaptation to hypoxia, expression and action of tumor suppressors and oncogenic mediators, and drug resistance. Thereby, they represent potential therapeutic targets. This narrative review aims at describing the involvement and regulation of SUMOylation and NEDDylation in tumor biology, with a specific focus on primary and secondary bone tumors, and to summarize and highlight their potentiality in diagnostics and therapeutic strategies.

HDAC8 suppresses the epithelial phenotype and promotes EMT in chemotherapy-treated basal-like breast cancer

BACKGROUND

Basal-like breast cancer (BLBC) is one of the most aggressive malignant diseases in women with an increased metastatic behavior and poor prognosis compared to other molecular subtypes of breast cancer. Resistance to chemotherapy is the main cause of treatment failure in BLBC. Therefore, novel therapeutic strategies counteracting the gain of aggressiveness underlying therapy resistance are urgently needed. The epithelial-to-mesenchymal transition (EMT) has been established as one central process stimulating cancer cell migratory capacity but also acquisition of chemotherapy-resistant properties. In this study, we aimed to uncover epigenetic factors involved in the EMT-transcriptional program occurring in BLBC cells surviving conventional chemotherapy.

RESULTS

Using whole transcriptome data from a murine mammary carcinoma cell line (pG-2), we identified upregulation of Hdac4, 7 and 8 in tumor cells surviving conventional chemotherapy. Subsequent analyses of human BLBC patient datasets and cell lines established HDAC8 as the most promising factor sustaining tumor cell viability. ChIP-sequencing data analysis identified a pronounced loss of H3K27ac at regulatory regions of master transcription factors (TFs) of epithelial phenotype like Gata3, Elf5, Rora and Grhl2 upon chemotherapy. Interestingly, impairment of HDAC8 activity reverted epithelial-TFs levels. Furthermore, loss of HDAC8 activity sensitized tumor cells to chemotherapeutic treatments, even at low doses.

CONCLUSION

The current study reveals a previously unknown transcriptional repressive function of HDAC8 exerted on a panel of transcription factors involved in the maintenance of epithelial cell phenotype, thereby supporting BLBC cell survival to conventional chemotherapy. Our data establish HDAC8 as an attractive therapeutically targetable epigenetic factor to increase the efficiency of chemotherapeutics.

Proteo-transcriptomics meta-analysis identifies SUMO2 as a promising target in glioblastoma multiforme therapeutics

Background

Glioblastoma multiforme (GBM) is a deadly brain tumour with minimal survival rates due to the ever-expanding heterogeneity, chemo and radioresistance. Kinases are known to crucially drive GBM pathology; however, a rationale therapeutic combination that can simultaneously inhibit multiple kinases has not yet emerged successfully.

Results

Here, we analyzed the GBM patient data from several publicly available repositories and deduced hub GBM kinases, most of which were identified to be SUMOylated by SUMO2/3 isoforms. Not only the hub kinases but a significant proportion of GBM upregulated genes involved in proliferation, metastasis, invasion, epithelial-mesenchymal transition, stemness, DNA repair, stromal and macrophages maintenance were also identified to be the targets of SUMO2 isoform. Correlatively, high expression of SUMO2 isoform was found to be significantly associated with poor patient survival.

Conclusions

Although many natural products and drugs are evidenced to target general SUMOylation, however, our meta-analysis strongly calls for the need to design SUMO2/3 or even better SUMO2 specific inhibitors and also explore the SUMO2 transcription inhibitors for universally potential, physiologically non-toxic anti-GBM drug therapy.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02279-y.

The major highlights of this study are as follows:

Key upregulated hub kinases and coding genes in GBM are found to be targets of SUMO2 conjugation.

SUMO2 is significantly expressed in adult primary and recurrent GBMs as well as in pediatric GBM tumours.

Orthotropic xenografts from adult and pediatric GBMs confirm high expression of SUMO2 in GBM tumour samples.

SUMO2 is significantly associated with patient survival plot and pan-cancer cell fitness.

Rationale design of SUMO2 inhibitors or search for its transcriptional inhibitors is urgently required through industry-academia collaboration for an anti-GBM and potentially pan-cancer therapeutics.

Lessons to Learn for Adequate Targeted Therapy Development in Metastatic Colorectal Cancer Patients

Insulin-like growth factor 1 receptor (IGF1R) is a receptor tyrosine kinase that regulates cell growth and proliferation. Upregulation of the IGF1R pathway constitutes a common paradigm shared with other receptor tyrosine kinases such as EGFR, HER2, and MET in different cancer types, including colon cancer. The main IGF1R signaling pathways are PI3K-AKT and MAPK-MEK. However, different processes, such as post-translational modification (SUMOylation), epithelial-to-mesenchymal transition (EMT), and microenvironment complexity, can also contribute to intrinsic and acquired resistance. Here, we discuss new strategies for adequate drug development in metastatic colorectal cancer patients.

Fragile Gene WWOX Guides TFAP2A/TFAP2C-Dependent Actions Against Tumor Progression in Grade II Bladder Cancer

INTRODUCTION

The presence of common fragile sites is associated with no-accidental chromosomal instability which occurs prior to carcinogenesis. The WWOX gene spans the second most active fragile site: FRA16D. Chromosomal breakage at this site is more common in bladder cancer patients who are tobacco smokers which suggests the importance of WWOX gene loss regarding bladder carcinogenesis. Tryptophan domains of WWOX are known to recognize motifs of other proteins such as AP-2α and AP-2γ allowing protein-protein interactions. While the roles of both AP-2 transcription factors are important for bladder carcinogenesis, their nature is different. Based on the literature, AP-2γ appears to be oncogenic, whereas AP-2α mainly exhibits tumor suppressor character. Presumably, the interaction between WWOX and both transcription factors regulates thousands of genes, hence the aim of the present study was to determine WWOX, AP-2α, and AP-2γ function in modulating biological processes of bladder cancer.

METHODS

RT-112 cell line (grade II bladder cancer) was subjected to two stable lentiviral transductions. Overall, this resulted in six variants to investigate distinct WWOX, AP-2α, or AP-2γ function as well as WWOX in collaboration with a particular transcription factor. Cellular models were examined with immunocytochemical staining and in terms of differences in biological processes using assays investigating cell viability, proliferation, apoptosis, adhesion, clonogenicity, migration, activity of metalloproteinases and 3D culture growth.

RESULTS

WWOX overexpression increased apoptosis but decreased cell viability, migration and large spatial colonies. AP-2α overexpression decreased tumor cell viability, migratory potential, matrix metalloproteinase-2 activity and clonogenicity. AP-2γ overexpression decreased matrix metalloproteinase-2 activity but increased wound healing, adhesion, clonogenicity and spatial colony formation. WWOX and AP-2α overexpression induced apoptosis but decreased cell viability, adhesion, matrix metalloproteinase-2 activity, overall number of cultured colonies and migration rate. WWOX and AP-2γ overexpression decreased tumor cell viability, proliferation potential, adhesion, clonogenicity and the ability to create spatial structures, but also increased apoptosis or migration rate.

CONCLUSION

Co-overexpression of WWOX with AP-2α or WWOX with AP-2γ resulted in a net anti-tumor effect. However, considering this research findings and the difference between AP-2α and AP-2γ, we suggest that this similarity is due to a divergent behavior of WWOX.

Kctd15 regulates nephron segment development by repressing Tfap2a activity

A functional vertebrate kidney relies on structural units called nephrons, which are epithelial tubules with a sequence of segments each expressing a distinct repertoire of solute transporters. The transcriptiona`l codes driving regional specification, solute transporter program activation and terminal differentiation of segment populations remain poorly understood. Here, we demonstrate that the KCTD15 paralogs kctd15a and kctd15b function in concert to restrict distal early (DE)/thick ascending limb (TAL) segment lineage assignment in the developing zebrafish pronephros by repressing Tfap2a activity. During renal ontogeny, expression of these factors colocalized with tfap2a in distal tubule precursors. kctd15a/b loss primed nephron cells to adopt distal fates by driving slc12a1, kcnj1a.1 and stc1 expression. These phenotypes were the result of Tfap2a hyperactivity, where kctd15a/b-deficient embryos exhibited increased abundance of this transcription factor. Interestingly, tfap2a reciprocally promoted kctd15a and kctd15b transcription, unveiling a circuit of autoregulation operating in nephron progenitors. Concomitant kctd15b knockdown with tfap2a overexpression further expanded the DE population. Our study reveals that a transcription factor-repressor feedback module employs tight regulation of Tfap2a and Kctd15 kinetics to control nephron segment fate choice and differentiation during kidney development.

Epithelial-mesenchymal transition polarization in ovarian carcinomas from patients with high social isolation

BACKGROUND

Social isolation has shown robust associations with clinical outcomes in the general population and in patients with cancer. In patients with ovarian cancer, social isolation has been found to be related to decreased survival and multiple biomarkers supporting tumor progression. However, to the authors' knowledge, little is known regarding the relationship between social isolation and the molecular characteristics of ovarian tumors. Herein, the authors have used genome-wide transcriptional profiling to quantify associations between social isolation and epithelial-mesenchymal transition (EMT) polarization in ovarian tumors and transcriptome-driven, promoter-based bioinformatics analyses to identify gene regulatory pathways that may potentially underlie these changes.

METHODS

Tumor was sampled during primary surgical resection and immediately frozen in liquid nitrogen. After RNA extraction, microarray analysis of the transcriptome was performed and samples were analyzed to assess associations between EMT-related gene transcripts and social isolation (as indicated by a Social Provisions Scale Attachment subscale score <15). Convergent validation was provided by a promoter-based bioinformatic analysis of transcription factor activity.

RESULTS

Primary analyses of 99 women demonstrated a lower average expression of gene transcripts previously associated with epithelial differentiation in women with high social isolation (-0.143 ± 0.048 log₂ mRNA abundance; P = .004), but no difference in mesenchymal differentiation as a function of social isolation (+0.007 ± 0.0064 log₂ mRNA abundance; P = .900). Upregulated activity was shown for 3 of the 4 targeted EMT-related transcription factors, including GATA4 (P = .014); SMAD2, SMAD3, and/or SMAD4 (P < .001); and TWIST1 (P < .001). Analyses of SNAIL2/SLUG activity indicated a directional trend toward increased activity that did not reach statistical significance (P = .123).

CONCLUSIONS

The findings of the current study demonstrated differential EMT polarization and EMT-related transcription factor activity according to social isolation, a known socioenvironmental risk factor.

LAY SUMMARY

Social isolation has shown robust associations with clinical outcomes in the general population and in patients with cancer. Herein, the authors examined the relationship between social isolation and the molecular characteristics of ovarian tumors. The authors investigated the epithelial-mesenchymal transition (EMT), a process whereby tumor cells lose epithelial characteristics and become more embryonic (mesenchymal), thereby enhancing invasiveness. Primary analyses demonstrated lower expression of genes previously associated with epithelial differentiation and increased activity of specific EMT-related transcription factors in individuals with high social isolation, indicating increased EMT polarization in these patients. These findings extend the understanding of how socioenvironmental factors may modulate tumor growth.

EMT Factors and Metabolic Pathways in Cancer

The epithelial-mesenchymal transition (EMT) represents a biological program during which epithelial cells lose their cell identity and acquire a mesenchymal phenotype. EMT is normally observed during organismal development, wound healing and tissue fibrosis. However, this process can be hijacked by cancer cells and is often associated with resistance to apoptosis, acquisition of tissue invasiveness, cancer stem cell characteristics, and cancer treatment resistance. It is becoming evident that EMT is a complex, multifactorial spectrum, often involving episodic, transient or partial events. Multiple factors have been causally implicated in EMT including transcription factors (e.g., SNAIL, TWIST, ZEB), epigenetic modifications, microRNAs (e.g., miR-200 family) and more recently, long non-coding RNAs. However, the relevance of metabolic pathways in EMT is only recently being recognized. Importantly, alterations in key metabolic pathways affect cancer development and progression. In this review, we report the roles of key EMT factors and describe their interactions and interconnectedness. We introduce metabolic pathways that are involved in EMT, including glycolysis, the TCA cycle, lipid and amino acid metabolism, and characterize the relationship between EMT factors and cancer metabolism. Finally, we present therapeutic opportunities involving EMT, with particular focus on cancer metabolic pathways.

Fluidity of Poly (ε-Caprolactone)-Based Material Induces Epithelial-to-Mesenchymal Transition

BACKGROUND

We propose the potential studies on material fluidity to induce epithelial to mesenchymal transition (EMT) in MCF-7 cells. In this study, we examined for the first time the effect of material fluidity on EMT using poly(ε-caprolactone-co-D,L-lactide) (P(CL-co-DLLA)) with tunable elasticity and fluidity.

METHODS

The fluidity was altered by chemically crosslinking the polymer networks. The crosslinked P(CL-co-DLLA) substrate showed a solid-like property with a stiffness of 261 kPa, while the non-crosslinked P(CL-co-DLLA) substrate of 100 units (high fluidity) and 500 units (low fluidity) existed in a quasi-liquid state with loss modulus of 33 kPa and 30.8 kPa, respectively, and storage modulus of 10.8 kPa and 20.1 kPa, respectively.

RESULTS

We observed that MCF-7 cells on low fluidic substrates decreased the expression of E-cadherin, an epithelial marker, and increased expression of vimentin, a mesenchymal marker. This showed that the cells lose their epithelial phenotype and gain a mesenchymal property. On the other hand, MCF-7 cells on high fluidic substrates maintained their epithelial phenotype, suggesting that the cells did not undergo EMT.

CONCLUSION

Considering these results as the fundamental information for material fluidity induced EMT, our system could be used to regulate the degree of EMT by turning the fluidity of the material.

MET inhibitors in cancer: pitfalls and challenges

Introduction: The HGF/MET axis is a key therapeutic pathway in cancer; it is aberrantly activated because of mutations, fusions, amplification or aberrant ligand production. Extensive efforts have been made to discover predictive factors of anti-MET therapeutic efficacy, but they have mostly unsuccessful. An understanding of the intrinsic and acquired mechanism of MET resistance will be fundamental for the development of new therapeutic interventions.Areas covered: This article provides a systematic review of phase II randomized and phase III clinical trials investigating the use of MET inhibitors in the treatment of cancer. We discuss preliminary findings on efficacy and methodologic design flaws in these trials.Expert opinion: MET inhibitors showed poor activity in unselected patients or patients selected by MET expression, p-MET or high HGF basal levels. The efficacy in advanced solid tumors is very modest and in phase III clinical trials, survival differences did not fulfill the stringent requirements of ESMO-Magnitude Clinical Benefit Score (MCBS). Prospective novel liquid biomarker-driven studies and novel trial designs such as Umbrella and Basket trials are necessary to progress MET inhibitor development.

SUMO3 modification by PIAS1 modulates androgen receptor cellular distribution and stability

Background

Abnormal reactivation of androgen receptor (AR) signaling in castration-resistant prostate cancer (CRPC) mainly results from overexpression and down-regulation of AR. Sumoylation of AR can influence its function. However, regulation of AR sumoylation by SUMO E3 ligases PIASs to modify AR distribution and stability are not well understood.

Methods

We assessed the potential effect of SUMO3 modification on AR intracellular localization by immunostaining in AR-negative prostate cancer DU145 cells, and detected the effect of PIAS1/SUMO3 overexpression on AR sumoylation related degradation. Then we characterized AR sumoylation sites involved modified by SUMO3, and the key residue of PIAS1 involved in itself sumoylation and further mediated AR sumoylation (sumo3-conjugated), translocation and degradation. Finally we detected the recognition of PIAS1 (sumoylation ligase) to MDM2, a ubiquin ligase mediated AR degradation.

Results

We demonstrate that SUMO E3 ligase PIAS1, along with SUMO3, mediates AR cytosolic translocation and subsequent degradation via a ubiquitin-proteasome pathway. Although AR sumoylation occurs prior to ubiquitination, the SUMO-acceptor lysine 386 on AR, together with ubiquitin-acceptor lysine 845, contribute to PIAS1/SUMO3-induced AR nuclear export, ubiquitination and subsequent degradation. Moreover, PIAS1 itself is modified by SUMO3 overexpression, and mutation of SUMO-acceptor lysine 117 on PIAS1 can impair AR cytoplasmic distribution, demonstrating the essential role of sumoylated PIAS1 in AR translocation. We further determine that sumoylated PIAS1 interacts with AR lysine 386 and 845 to form a binary complex. Consistent with the effect on AR distribution, SUMO3 modification of PIAS1 is also required for AR ubiquitination and degradation by recruiting ubiquitin E3 ligase MDM2.

Conclusion

Taken together, SUMO3 modification of PIAS1 modulates AR cellular distribution and stability. Our study provided the evidence the crosstalk between AR sumoylation and ubquitination mediated by PIAS1 and SUMO3.

MEG3 affects the progression and chemoresistance of T-cell lymphoblastic lymphoma by suppressing epithelial-mesenchymal transition via the PI3K/mTOR pathway

Long noncoding RNAs (lncRNA) are emerging as integral functional and regulatory components in the development of different diseases including cancer. Maternally expressed gene 3 (MEG3), is a lncRNA, that has a depressed expression in multiple tumor types, including T-cell lymphoblastic lymphoma (T-LBL). However, the molecular mechanisms that regulate the tumorigenic functions of MEG3 in T-LBL remain largely unknown. In this study, we aimed to discover and identify the function of MEG3 in T-LBL tumorigenesis, epithelial-mesenchymal transition (EMT) and drug resistance, and explore their mechanisms of action. Knockdown MEG3 promoted the proliferation, migration, invasion, and drug resistance of T-LBL cells while overexpression of MEG3 gets the opposite results. The mechanism study showed that decreased MEG3 expression in T-LBL cells could activate PI3K/mTOR signaling pathways, increase the expression of p-glycoprotein and affect the expression of EMT markers for transforming to mesenchymal cells in vitro and in vivo. Together, these results indicate that MEG3 could inhibit the migration, invasion, and drug resistance in T-LBL cells by suppression of the PI3K/mTOR pathway. MEG3 might be a potential target, through which poor prognosis with high recurrence and drug resistance of T-LBL in a clinical setting could be reversed.

LRG‑1 enhances the migration of thyroid carcinoma cells through promotion of the epithelial‑mesenchymal transition by activating MAPK/p38 signaling

Leucine-rich-alpha-2-glycoprotein 1 (LRG-1) has been reported to be associated with multiple malignancies. However, its participation in thyroid carcinoma progression remains unclear. In the present study, the biological function and underlying molecular mechanisms of LRG-1 in thyroid carcinoma were investigated. It was found that LRG-1 was overexpressed in thyroid carcinoma tissues, and high LRG-1 expression predicted poor patient survival and late tumor stage. As shown in the mouse xenograft study, knockdown of LRG-1 significantly attenuated thyroid cancer growth in vivo. Based on wound healing, Transwell, proliferation and apoptosis assays, it was found that the knockdown of LRG-1, using shLRG-1, inhibited cell migration and invasion, but did not affect proliferation and apoptosis in thyroid cancer cells. Furthermore, LRG-1 also induced epithelial-mesenchymal transition (EMT) in thyroid carcinoma cells. Western blot analysis revealed that this tumor-promoting bioactivity of LRG-1 was attributed to its selective activation of MAPK/p38 signaling. All of these findings indicate that LRG-1 plays a deleterious role in the progression of thyroid carcinoma. LRG-1 may serve as a promising biomarker for predicting prognosis in thyroid carcinoma patients, and LRG-1-based therapy may be developed into a novel strategy for the treatment of thyroid carcinoma.

Developing Practical Therapeutic Strategies that Target Protein SUMOylation

Post-translational modification by small ubiquitin-like modifier (SUMO) has emerged as a global mechanism for the control and integration of a wide variety of biological processes through the regulation of protein activity, stability and intracellular localization. As SUMOylation is examined in greater detail, it has become clear that the process is at the root of several pathologies including heart, endocrine, and inflammatory disease, and various types of cancer. Moreover, it is certain that perturbation of this process, either globally or of a specific protein, accounts for many instances of congenital birth defects. In order to be successful, practical strategies to ameliorate conditions due to disruptions in this post-translational modification will need to consider the multiple components of the SUMOylation machinery and the extraordinary number of proteins that undergo this modification.

Epithelial-Mesenchymal Transition and Metastasis under the Control of Transforming Growth Factor β

Metastasis of tumor cells from primary sites of malignancy to neighboring stromal tissue or distant localities entails in several instances, but not in every case, the epithelial-mesenchymal transition (EMT). EMT weakens the strong adhesion forces between differentiated epithelial cells so that carcinoma cells can achieve solitary or collective motility, which makes the EMT an intuitive mechanism for the initiation of tumor metastasis. EMT initiates after primary oncogenic events lead to secondary secretion of cytokines. The interaction between tumor-secreted cytokines and oncogenic stimuli facilitates EMT progression. A classic case of this mechanism is the cooperation between oncogenic Ras and the transforming growth factor β (TGFβ). The power of TGFβ to mediate EMT during metastasis depends on versatile signaling crosstalk and on the regulation of successive waves of expression of many other cytokines and the progressive remodeling of the extracellular matrix that facilitates motility through basement membranes. Since metastasis involves many organs in the body, whereas EMT affects carcinoma cell differentiation locally, it has frequently been debated whether EMT truly contributes to metastasis. Despite controversies, studies of circulating tumor cells, studies of acquired chemoresistance by metastatic cells, and several (but not all) metastatic animal models, support a link between EMT and metastasis, with TGFβ, often being a common denominator in this link. This article aims at discussing mechanistic cases where TGFβ signaling and EMT facilitate tumor cell dissemination.

The SUMO System and TGFβ Signaling Interplay in Regulation of Epithelial-Mesenchymal Transition: Implications for Cancer Progression

Protein post-translational modification by the small ubiquitin-like modifier (SUMO), or SUMOylation, can regulate the stability, subcellular localization or interactome of a protein substrate with key consequences for cellular processes including the Epithelial-Mesenchymal Transition (EMT). The secreted protein Transforming Growth Factor beta (TGFβ) is a potent inducer of EMT in development and homeostasis. Importantly, the ability of TGFβ to induce EMT has been implicated in promoting cancer invasion and metastasis, resistance to chemo/radio therapy, and maintenance of cancer stem cells. Interestingly, TGFβ-induced EMT and the SUMO system intersect with important implications for cancer formation and progression, and novel therapeutics identification.

Precision medicine in cholangiocarcinoma

Cholangiocarcinoma is one of the epithelial cancers with the poorest prognosis and the narrowest therapeutic choice in humans. Compared with other cancer types, cholangiocarcinoma has been often neglected by oncology and liver research studies, thereby leaving many issues unsolved. Apart from the early and marked aggressiveness, one of the main reasons of the still unsatisfying clinical management of cholangiocarcinoma is its wide tumor heterogeneity needing more than other diseases a 'precision medicine' approach. In this regard, in the last few years there has been an awakening of interest aimed at dissecting the complex molecular and genomic profile of cholangiocarcinoma. Thus, a range of molecular players have been recently identified as putative mechanistic determinants of cholangiocarcinoma invasiveness, encompassing tyrosine kinase receptors, metabolic enzymes, transcription factors, small GTPases, ubiquitin ligases, and chromatin-remodelling proteins, whose aberrant expression may derive from stochastic mutations as well as from pro-oncogenic paracrine signals released by the stromal microenvironment, which is particularly exuberant in cholangiocarcinoma. Herein, we sought to overview the most relevant observations unravelling the genomic landscape of cholangiocarcinoma, and the prognostic and predictive biomarkers that consequently have been emerging. Then, we will discuss innovative treatment approaches derived from conventional chemotherapy, targeted therapies, antiangiogenic therapies and immunotherapy, and how they are opening new avenues towards a precision medicine in cholangiocarcinoma.

Molecular Mechanisms Driving Cholangiocarcinoma Invasiveness: An Overview

The acquisition of invasive functions by tumor cells is a first and crucial step toward the development of metastasis, which nowadays represents the main cause of cancer-related death. Cholangiocarcinoma (CCA), a primary liver cancer originating from the biliary epithelium, typically develops intrahepatic or lymph node metastases at early stages, thus preventing the majority of patients from undergoing curative treatments, consistent with their very poor prognosis. As in most carcinomas, CCA cells gradually adopt a motile, mesenchymal-like phenotype, enabling them to cross the basement membrane, detach from the primary tumor, and invade the surrounding stroma. Unfortunately, little is known about the molecular mechanisms that synergistically orchestrate this proinvasive phenotypic switch. Autocrine and paracrine signals (cyto/chemokines, growth factors, and morphogens) permeating the tumor microenvironment undoubtedly play a prominent role in this context. Moreover, a number of recently identified signaling systems are currently drawing attention as putative mechanistic determinants of CCA cell invasion. They encompass transcription factors, protein kinases and phosphatases, ubiquitin ligases, adaptor proteins, and miRNAs, whose aberrant expression may result from either stochastic mutations or the abnormal activation of upstream pro-oncogenic pathways. Herein we sought to summarize the most relevant molecules in this field and to discuss their mechanism of action and potential prognostic relevance in CCA. Hopefully, a deeper knowledge of the molecular determinants of CCA invasiveness will help to identify clinically useful biomarkers and novel druggable targets, with the ultimate goal to develop innovative approaches to the management of this devastating malignancy.

Knockdown of Long Noncoding RNA ENST457720 Inhibits Proliferation of Non-Small Cell Lung Cancer Cells In Vitro and In Vivo

Non-small cell lung cancer (NSCLC) represents the leading cause of cancer-related mortality worldwide. More and more reports have identified important roles for long noncoding RNAs (lncRNAs) in cancer development. ENST457720 expression was upregulated in lung adenocarcinoma in a microarray-based lncRNA screen. We determined the expression levels of ENST457720 in NSCLC tissues with quantitative real-time PCR and then studied their clinical significance. We explored the biological significance of ENST457720 with gain- and loss-of-function analyses in vitro and in vivo. In this study, ENST457720 was expressed at higher levels in NSCLC tissues than in paired normal tissues. Higher ENST457720 expression was associated with larger tumor sizes, lymph node metastasis, and advanced TNM stage. ENST457720 silencing suppressed NSCLC cell proliferation in vitro and in vivo. Moreover, ENST457720 knockdown inhibited NSCLC invasion and reversed the epithelial-to-mesenchymal transition. ENST457720 promoted NSCLC proliferation and invasion, which may be a novel potential therapeutic target for NSCLC.

Akt Protein Kinase, miR-200/miR-182 Expression and Epithelial-Mesenchymal Transition Proteins in Hibernating Ground Squirrels

Hibernating 13-lined ground squirrels (Ictidomys tridecemlineatus; TLGS) rank among the most brain hypoperfusion-tolerant mammals known. Herein we provide some evidence of cycling between an epithelial phenotype and a hybrid epithelial/mesenchymal (E/M) phenotype (partial EMT) within the brains of TLGS during each bout of hibernation torpor. During hibernation torpor, expression of the epithelial marker E-cadherin (E-CDH) was reduced, while expression of the well-known mesenchymal markers vimentin and Sox2 were increased. P-cadherin (P-CDH), which has recently been proposed as a marker of intermediate/partial EMT, also increased during torpor, suggesting that a partial EMT may be taking place during hibernation torpor. Members of the miR-200 family and miR-182 cluster and Akt isoforms (Akt1, Akt2), well-known EMT regulators, were also differentially regulated in the TLGS brain during hibernation bouts. Using SHSY5Y cells, we also demonstrate that the Akt1/Akt2 ratio determined the expression levels of miR-200/miR-182 miRNA family members, and that these miRNAs controlled the expression of EMT-related proteins. Accordingly, we propose that such cell state transitions (EMT/MET) may be one of the mechanisms underlying the extraordinary ischemic tolerance of the TLGS brain during hibernation bouts; hibernator brain cells appear to enter reversible states that confer the stress survival characteristics of cancer cells without the risk of neoplastic transformation.

DeSUMOylation of MKK7 kinase by the SUMO2/3 protease SENP3 potentiates lipopolysaccharide-induced inflammatory signaling in macrophages

Protein SUMOylation has been reported to play a role in innate immune response, but the enzymes, substrates, and consequences of the specific inflammatory signaling events are largely unknown. Reactive oxygen species (ROS) are abundantly produced during macrophage activation and required for Toll-like receptor 4 (TLR4)-mediated inflammatory signaling. Previously, we demonstrated that SENP3 is a redox-sensitive SUMO2/3 protease. To explore any links between reversible SUMOylation and ROS-related inflammatory signaling in macrophage activation, we generated mice with Senp3 conditional knock-out in myeloid cells. In bacterial lipopolysaccharide (LPS)-induced in vitro and in vivo inflammation models, we found that SENP3 deficiency markedly compromises the activation of TLR4 inflammatory signaling and the production of proinflammatory cytokines in macrophages exposed to LPS. Moreover, Senp3 conditional knock-out mice were significantly less susceptible to septic shock. Of note, SENP3 deficiency was associated with impairment in JNK phosphorylation. We found that MKK7, which selectively phosphorylates JNK, is a SENP3 substrate and that SENP3-mediated deSUMOylation of MKK7 may favor its binding to JNK. Importantly, ROS-dependent SENP3 accumulation and MKK7 deSUMOylation rapidly occurred after LPS stimulation. In conclusion, our findings indicate that SENP3 potentiates LPS-induced TLR4 signaling via deSUMOylation of MKK7 leading to enhancement in JNK phosphorylation and the downstream events. Therefore this work provides novel mechanistic insights into redox regulation of innate immune responses.

Polo-like kinase 4 mediates epithelial-mesenchymal transition in neuroblastoma via PI3K/Akt signaling pathway

Neuroblastoma (NB) is the most common malignant tumor in infancy and most common extracranial solid tumor in childhood. With the improvement of diagnosis and treatment, the survival rate of patients with low-risk and intermediate-risk NB can reach up to 90%. In contrast, for high-risk NBs, the long-term survival rate is still <40% because of heterogeneity of this tumor. The pathogenesis of NB is still not explicit, therefore it is of great significance to explore the mechanism of NB tumorigenesis and discover new therapeutic targets for NB. Polo-like kinase 4 (PLK4), one of the polo-like kinase family members, is an important regulator of centriole replication. The aberrant expression of PLK4 was found in several cancers and a recent study has unraveled a novel function of PLK4 as a mediator of invasion and metastasis in Hela and U2OS cells. However, the function of PLK4 in NB development and progression remains to be elucidated. The study showed the expression level of PLK4 in NB tissues was remarkably upregulated and high expression of PLK4 was negatively correlated with clinical features and survival, which suggested that PLK4 could be a potential tumor-promoting factor of NB. Functional studies indicated downregulation of PLK4 suppressed migration and invasion and promoted apoptosis in NB cells. Further experiments showed that downregulation of PLK4 in NB cells inhibited EMT through the PI3K/Akt signaling pathway. Animal experiments demonstrated that the downregulation of PLK4 in SK-N-BE(2) cells dramatically suppressed tumorigenesis and metastasis. PLK4 may be a promising therapeutic target for NB.

Targeting the SUMO pathway as a novel treatment for anaplastic thyroid cancer

Cancer stem cells (CSCs) are expanded in anaplastic thyroid cancer (ATC) and standard treatment approaches have failed to improve survival, suggesting a need to specifically target the CSC population. Recent studies in breast and colorectal cancer demonstrated that inhibition of the SUMO pathway repressed CD44 and cleared the CSC population, mediated through SUMO-unconjugated TFAP2A. We sought to evaluate effects of inhibiting the SUMO pathway in ATC. ATC cell lines and primary ATC tumor samples were evaluated. The SUMO pathway was inhibited by knockdown of PIAS1 and use of SUMO inhibitors anacardic acid and PYR-41. The expression of TFAP2A in primary ATC was examined by immunohistochemistry. All ATC cell lines expressed TFAP2A but only 8505C expressed SUMO-conjugated TFAP2A. In 8505C only, inhibition of the SUMO pathway by knockdown of PIAS1 or treatment with SUMO inhibitors repressed expression of CD44 with a concomitant loss of SUMO-conjugated TFAP2A. The effect of SUMO inhibition on CD44 expression was dependent upon TFAP2A. Treatment with SUMO inhibitors resulted in a statistically improved tumor-free survival in mice harboring 8505C xenografts. An examination of primary ATC tissue determined that TFAP2A was expressed in 4 of 11 tumors surveyed. We conclude that inhibition of the SUMO pathway repressed the CSC population, delaying the outgrowth of tumor xenografts in ATC. The effect of SUMO inhibition was dependent upon expression of SUMO-conjugated TFAP2A, which may serve as a molecular marker for therapeutic effects of SUMO inhibitors. The findings provide pre-clinical evidence for development of SUMO inhibitors for the treatment of ATC.

Topotecan is a potent inhibitor of SUMOylation in glioblastoma multiforme and alters both cellular replication and metabolic programming

Protein SUMOylation is a dynamic post-translational modification shown to be involved in a diverse set of physiologic processes throughout the cell. SUMOylation has also been shown to play a role in the pathobiology of myriad cancers, one of which is glioblastoma multiforme (GBM). As such, the clinical significance and therapeutic utility offered via the selective control of global SUMOylation is readily apparent. There are, however, relatively few known/effective inhibitors of global SUMO-conjugation. Herein we describe the identification of topotecan as a novel inhibitor of global SUMOylation. We also provide evidence that inhibition of SUMOylation by topotecan is associated with reduced levels of CDK6 and HIF-1α, as well as pronounced changes in cell cycle progression and cellular metabolism, thereby highlighting its putative role as an adjuvant therapy in defined GBM patient populations.

Identification of clinically predictive metagenes that encode components of a network coupling cell shape to transcription by image-omics

The associations between clinical phenotypes (tumor grade, survival) and cell phenotypes, such as shape, signaling activity, and gene expression, are the basis for cancer pathology, but the mechanisms explaining these relationships are not always clear. The generation of large data sets containing information regarding cell phenotypes and clinical data provides an opportunity to describe these mechanisms. Here, we develop an image-omics approach to integrate quantitative cell imaging data, gene expression, and protein-protein interaction data to systematically describe a "shape-gene network" that couples specific aspects of breast cancer cell shape to signaling and transcriptional events. The actions of this network converge on NF-κB, and support the idea that NF-κB is responsive to mechanical stimuli. By integrating RNAi screening data, we identify components of the shape-gene network that regulate NF-κB in response to cell shape changes. This network was also used to generate metagene models that predict NF-κB activity and aspects of morphology such as cell area, elongation, and protrusiveness. Critically, these metagenes also have predictive value regarding tumor grade and patient outcomes. Taken together, these data strongly suggest that changes in cell shape, driven by gene expression and/or mechanical forces, can promote breast cancer progression by modulating NF-κB activation. Our findings highlight the importance of integrating phenotypic data at the molecular level (signaling and gene expression) with those at the cellular and tissue levels to better understand breast cancer oncogenesis.

Clinical significance of SLP-2 in hepatocellular carcinoma tissues and its regulation in cancer cell proliferation, migration, and EMT

Stomatin-like protein 2 (SLP-2) gene was significantly upregulated in a variety of tumor tissues and found to be involved in proliferation and metastasis. However, its functional role in hepatocellular carcinoma (HCC) remains unknown. Our study was to investigate the function of SLP-2 in cell proliferation, migration, invasion, cell apoptosis, and the process of epithelial-mesenchymal transition (EMT) in HCC. SLP-2 mRNA and protein expression in HCC were assessed by qRT-PCR and immunohistochemical staining. In vitro, we determined cell proliferation, migration, invasion, and cell apoptosis by CCK-8, transwell, and flow cytometry assays, respectively. SLP-2 was found to be upregulated at both mRNA and protein levels in HCC tissues, and its aberrant overexpression was linked with poor prognosis in patients with HCC. SLP-2 downregulation by siRNAs significantly suppressed cell proliferation, migration, invasion, anti-apoptosis abilities, and inhibited EMT process in vitro. In conclusion, the present study demonstrated the overexpression of SLP-2 in HCC tissues for the first time. As an effective regulator involved in cell proliferation, migration, invasion, cell apoptosis, and EMT, SLP-2 could be a novel therapeutic target for patients with HCC who express high levels of SLP-2.

Inhibiting the SUMO Pathway Represses the Cancer Stem Cell Population in Breast and Colorectal Carcinomas

Many solid cancers have an expanded CD44^+/hi/CD24^−/low cancer stem cell (CSC) population, which are relatively chemoresistant and drive recurrence and metastasis. Achieving a more durable response requires the development of therapies that specifically target CSCs. Recent evidence indicated that inhibiting the SUMO pathway repressed tumor growth and invasiveness, although the mechanism has yet to be clarified. Here, we demonstrate that inhibition of the SUMO pathway repressed MMP14 and CD44 with a concomitant reduction in cell invasiveness and functional loss of CSCs in basal breast cancer. Similar effects were demonstrated with a panel of E1 and E3 SUMO inhibitors. Identical results were obtained in a colorectal cancer cell line and primary colon cancer cells. In both breast and colon cancer, SUMO-unconjugated TFAP2A mediated the effects of SUMO inhibition. These data support the development of SUMO inhibitors as an approach to specifically target the CSC population in breast and colorectal cancer.

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Sumoylation regulates CD44 and MMP14 expression in basal breast and colon cancer

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SUMO inhibition clears cancer stem cells, repressing invasiveness and tumor growth

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Anacardic acid functions as a SUMO inhibitor to repress cancer stem cells

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TFAP2A mediates anti-tumor effects of SUMO inhibition in breast and colon cancers

Lysine 63 ubiquitination is involved in the progression of tubular damage in diabetic nephropathy

The purpose of our study was to evaluate how hyperglycemia (HG) influences Lys63 protein ubiquitination and its involvement in tubular damage and fibrosis in diabetic nephropathy (DN). Gene and protein expression of UBE2v1, a ubiquitin-conjugating E2-enzyme variant that mediates Lys63-linked ubiquitination, and Lys63-ubiquitinated proteins increased in HK2 tubular cells under HG. Matrix-assisted laser desorption/ionization-time of flight/tandem mass spectrometry identified 30 Lys63-ubiquitinated proteins, mainly involved in cellular organization, such as β-actin, whose Lys63 ubiquitination increased under HG, leading to cytoskeleton disorganization. This effect was reversed by the inhibitor of the Ubc13/UBE2v1 complex NSC697923. Western blot analysis confirmed that UBE2v1 silencing in HK2 under HG, restored Lys63-β-actin ubiquitination levels to the basal condition. Immunohistochemistry on patients with type 2 diabetic (T2D) revealed an increase in UBE2v1- and Lys63-ubiquitinated proteins, particularly in kidneys of patients with DN compared with control kidneys and other nondiabetic renal diseases, such as membranous nephropathy. Increased Lys63 ubiquitination both in vivo in patients with DN and in vitro, correlated with α-SMA expression, whereas UBE2v1 silencing reduced HG-induced α-SMA protein levels, returning them to basal expression. In conclusion, UBE2v1- and Lys63-ubiquitinated proteins increase in vitro under HG, as well as in vivo in T2D, is augmented in patients with DN, and may affect cytoskeleton organization and influence epithelial-to-mesenchymal transition. This process may drive the progression of tubular damage and interstitial fibrosis in patients with DN.-Pontrelli, P., Conserva, F., Papale, M., Oranger, A., Barozzino, M., Vocino, G., Rochetti, M. T., Gigante, M., Castellano, G., Rossini, M., Simone, S., Laviola, L., Giorgino, F., Grandaliano, G., Di Paolo, S., Gesualdo, L. Lysine 63 ubiquitination is involved in the progression of tubular damage in diabetic nephropathy.

RARγ Downregulation Contributes to Colorectal Tumorigenesis and Metastasis by Derepressing the Hippo-Yap Pathway

The Hippo-Yap pathway conveys oncogenic signals, but its regulation during cancer development is not well understood. Here, we identify the nuclear receptor RARγ as a regulator of the Hippo-Yap pathway in colorectal tumorigenesis and metastasis. RARγ is downregulated in human colorectal cancer tissues, where its expression correlates inversely with tumor size, TNM stage, and distant metastasis. Functional studies established that silencing of RARγ drove colorectal cancer cell growth, invasion, and metastatic properties both in vitro and in vivo Mechanistically, RARγ controlled Hippo-Yap signaling to inhibit colorectal cancer development, acting to promote phosphorylation and binding of Lats1 to its transcriptional coactivator Yap and thereby inactivating Yap target gene expression. In clinical specimens, RARγ expression correlated with overall survival outcomes and expression of critical Hippo-Yap pathway effector molecules in colorectal cancer patients. Collectively, our results defined RARγ as tumor suppressor in colorectal cancer that acts by restricting oncogenic signaling by the Hippo-Yap pathway, with potential implications for new approaches to colorectal cancer therapy. Cancer Res; 76(13); 3813-25. ©2016 AACR.

Low-Dose Paclitaxel Reduces S100A4 Nuclear Import to Inhibit Invasion and Hematogenous Metastasis of Cholangiocarcinoma

Nuclear expression of the calcium-binding protein S100A4 is a biomarker of increased invasiveness in cholangiocarcinoma, a primary liver cancer with scarce treatment opportunities and dismal prognosis. In this study, we provide evidence that targeting S100A4 nuclear import by low-dose paclitaxel, a microtubule-stabilizing agent, inhibits cholangiocarcinoma invasiveness and metastatic spread. Administration of low-dose paclitaxel to established (EGI-1) and primary (CCA-TV3) cholangiocarcinoma cell lines expressing nuclear S100A4 triggered a marked reduction in nuclear expression of S100A4 without modifying its cytoplasmic levels, an effect associated with a significant decrease in cell migration and invasiveness. While low-dose paclitaxel did not affect cellular proliferation, apoptosis, or cytoskeletal integrity, it significantly reduced SUMOylation of S100A4, a critical posttranslational modification that directs its trafficking to the nucleus. This effect of low-dose paclitaxel was reproduced by ginkolic acid, a specific SUMOylation inhibitor. Downregulation of nuclear S100A4 by low-dose paclitaxel was associated with a strong reduction in RhoA and Cdc42 GTPase activity, MT1-MMP expression, and MMP-9 secretion. In an SCID mouse xenograft model, low-dose metronomic paclitaxel treatment decreased lung dissemination of EGI-1 cells without significantly affecting their local tumor growth. In the tumor mass, nuclear S100A4 expression by cholangiocarcinoma cells was significantly reduced, whereas rates of proliferation and apoptosis were unchanged. Overall, our findings highlight nuclear S100A4 as a candidate therapeutic target in cholangiocarcinoma and establish a mechanistic rationale for the use of low-dose paclitaxel in blocking metastatic progression of cholangiocarcinoma. Cancer Res; 76(16); 4775-84. ©2016 AACR.

Overexpressed targeting protein for Xklp2 (TPX2) serves as a promising prognostic marker and therapeutic target for gastric cancer

The targeting protein for Xenopus kinesin-like protein 2 (TPX2) is a putative oncogene in different human cancers. This study assessed TPX2 expression in gastric cancer tissue samples and then determined the effects of TPX2 knockdown on the regulation of gastric cancer cell malignant behaviors in vitro. Tissue samples from 115 gastric cancer patients were analyzed for TPX2 expression. The effects of TPX2 siRNA on gastric cancer cells were assessed in vitro, including cell viability, cell cycle distribution, apoptosis, migration, and invasion. The data showed that TPX2 was overexpressed in gastric cancer tissues compared to that in the adjacent normal epithelia. Moreover, TPX2 overexpression was associated with a poor overall survival and was an independent prognostic predictor of gastric cancer. In addition, the in vitro study further confirmed the ex vivo data, i.e., knockdown of TPX2 expression reduced gastric cancer cell viability but induced apoptosis and arrested cells at the G2/M phase of the cell cycle. Knockdown of TPX2 expression also inhibited the tumor cell migration and invasion capacity in vitro. At the gene level, knockdown of TPX2 expression upregulated the levels of cyclin B1, cdk4, p53, Bax, caspase-3, and E-cadherin, but downregulated the levels of cyclin D1, cdk2, N-cadherin, slug, matrix metalloprotease (MMP)-2, and MMP-9, suggesting that knockdown of TPX2 expression suppressed tumor cell epithelial-mesenchymal transition (EMT). This study demonstrated that detection of TPX2 overexpression could serve as a prognostic marker and therapeutic target for gastric cancer.

The Ubiquitin-like Protein FAT10 Stabilizes eEF1A1 Expression to Promote Tumor Proliferation in a Complex Manner

Human HLA-F adjacent transcript 10 (FAT10) is the only ubiquitin-like protein that can directly target substrates for degradation by proteasomes, but it can also stabilize the expression of certain substrates by antagonizing ubiquitination, through mechanisms as yet uncharacterized. In this study, we show how FAT10 stabilizes the translation elongation factor eEF1A1, which contributes to cancer cell proliferation. FAT10 overexpression increased expression of eEF1A1, which was sufficient to promote proliferation of cancer cells. Mechanistic investigations revealed that FAT10 competed with ubiquitin (Ub) for binding to the same lysines on eEF1A1 to form either FAT10-eEF1A1 or Ub-eEF1A1 complexes, respectively, such that FAT10 overexpression decreased Ub-eEF1A1 levels and increased FAT10-eEF1A1 levels. Overall, our work establishes a novel mechanism through which FAT10 stabilizes its substrates, advancing understanding of the biological function of FAT10 and its role in cancer. Cancer Res; 76(16); 4897-907. ©2016 AACR.

MiR-361-5p inhibits colorectal and gastric cancer growth and metastasis by targeting staphylococcal nuclease domain containing-1

MicroRNAs (miRs) function as key regulators of gene expression and their deregulation is associated with the carcinogenesis of various cancers. In the present study, we investigated the biological role and mechanism of miR-361-5p in colorectal carcinoma (CRC) and gastric cancer (GC). We showed that microRNA-361-5p (miR-361-5p) was down-regulated in CRC and GC in comparison to the controls. Meanwhile, the expression levels of miR-361-5p negatively correlated with lung metastasis and prognosis in clinical CRC patients. Overexpression of miR-361-5p markedly suppressed proliferation, migration and invasion of cancer cells. Additionally, this phenotype could be partially rescued by the ectopic expression of staphylococcal nuclease domain containing-1 (SND1). SND1 was identified as a target of miR-361-5p using bioinformatics analysis and in vitro luciferase reporter assays. In turn, SND1 bound to pre-miR-361-5p and suppressed the expression of miR-361-5p, thus exerting a feedback loop. Most interestingly, in vivo studies showed that restoration of miR-361-5p significantly inhibited tumor growth and especially the lung metastasis in nude mice. Therefore, it could be concluded that miR-361-5p functions as a tumor-suppressive miRNA through directly binding to SND1, highlighting its potential as a novel agent for the treatment of patients with CRC and GC.

Regulation of epithelial-mesenchymal transition through epigenetic and post-translational modifications

The epithelial to mesenchymal transition (EMT) is a biological process in which a non-motile epithelial cell changes to a mesenchymal phenotype with invasive capacities. This phenomenon has been well documented in multiple biological processes including embryogenesis, fibrosis, tumor progression and metastasis. The hallmark of EMT is the loss of epithelial surface markers, most notably E-cadherin, and the acquisition of mesenchymal markers including vimentin and N-cadherin. The downregulation of E-cadherin during EMT can be mediated by its transcriptional repression through the binding of EMT transcription factors (EMT-TFs) such as SNAIL, SLUG and TWIST to E-boxes present in the E-cadherin promoter. Additionally, EMT-TFs can also cooperate with several enzymes to repress the expression of E-cadherin and regulate EMT at the epigenetic and post- translational level. In this review, we will focus on epigenetic and post- translational modifications that are important in EMT. In addition, we will provide an overview of the various therapeutic approaches currently being investigated to undermine EMT and hence, the metastatic progression of cancer as well.

Long noncoding RNA ENST00000434223 suppressed tumor progression in non-small cell lung cancer

In spite of the fact that the great progress has been made in the treatment of non-small cell lung cancer (NSCLC), the prognosis of NSCLC remains comparatively dismal. Therefore, it is of great value to identify novel effective diagnostic biomarkers and therapeutic targets of NSCLC. Emerging evidence has demonstrated the vital roles of long noncoding RNAs (lncRNAs) in cancer development. ENST00000434223 was recently identified as a lncRNA that is downregulated in early stage lung adenocarcinoma in a profiling study. However, little is known about its role in the development of NSCLC. In the present study, we found that ENST00000434223 was greatly downregulated in cancer tissues compared to adjacent normal tissues. ENST00000434223 overexpression suppressed the proliferation and migration in NSCLC cell lines in vitro. Moreover, ENST00000434223 overexpression reversed the epithelial-mesenchymal transition in NSCLC cell line. Our study suggests that ENST00000434223 may be a potential biomarker and a therapeutic target of NSCLC.

SENP1 regulates hepatocyte growth factor-induced migration and epithelial-mesenchymal transition of hepatocellular carcinoma

The deregulation of HGF/c-Met signaling is implicated in epithelial-mesenchymal transition (EMT) and progress of hepatocellular carcinoma (HCC). However, the epigenetic mechanisms that HGF/c-Met regulates EMT and metastasis of HCC cells are less explored. In this study, we demonstrated that HCC cells express a high level of SUMO/sentrin-specific protease 1 (Senp1) which is induced by HGF/c-Met signals. Lentivirus-mediated small hairpin RNA (shRNA) transduction results in Senp1 silence in HCC cells. Senp1 silence reduces the HGF-induced proliferation and migration of HCC cells. Senp1 inhibition also induces HCC cell apoptosis and growth arrest. Furthermore, Senp1 knockdown inhibits epithelial-to-mesenchymal transition, with increase of E-cadherin and ZO-1 expression, decrease of fibronectin and N-cadherin expression. The EMT-related transcription factor Zeb1 was SUMO-modified and decreased in Senp1-silenced HCC cells. These results delineate that senp1 might play an important role in the regulation of HGF-induced invasion and migration of HCC cells.

Clinical relevance of host immunity in breast cancer: from TILs to the clinic

The clinical relevance of the host immune system in breast cancer has long been unexplored. Studies developed over the past decade have highlighted the biological heterogeneity of breast cancer, prompting researchers to investigate whether the role of the immune system in this malignancy is similar across different molecular subtypes of the disease. The presence of high levels of lymphocytic infiltration has been consistently associated with a more-favourable prognosis in patients with early stage triple-negative and HER2-positive breast cancer. These infiltrates seem to reflect favourable host antitumour immune responses, suggesting that immune activation is important for improving survival outcomes. In this Review, we discuss the composition of the immune infiltrates observed in breast cancers, as well as data supporting the clinical relevance of host antitumour immunity, as represented by lymphocytic infiltration, and how this biomarker could be used in the clinical setting. We also discuss the rationale for enhancing immunity in breast cancer, including early data on the efficacy of T-cell checkpoint inhibition in this setting.

Epithelial–mesenchymal transition in prostatic disease

A fully differentiated epithelium of the normal prostate gland allows epithelial cells to de-differentiate into mesenchymal-like derivatives via the process of epithelial–mesenchymal transition (EMT) and redifferentiate via the reverse process, mesenchymal–epithelial transition. This review discusses the phenotypic changes associated with EMT and its programming in the development of the two growth disorders of the aging prostate gland, benign prostatic hyperplasia and prostate adenocarcinoma. Considering the cellular heterogeneity that characterizes both conditions, identifying the transcriptional programming of the phenotypic framework defining EMT and its reverse process mesenchymal–epithelial transition in their pathological landscape will enable novel platforms for biomarker-driven therapeutics and their implementation in benign prostatic hyperplasia and prostate cancer.

Pc2-mediated SUMOylation of WWOX is essential for its suppression of DU145 prostate tumorigenesis

Tumor suppressor WW domain-containing oxidoreductase (WWOX) is depleted in various cancer types. Here we report that WWOX is modified by small ubiquitin-like modifier (SUMO) proteins and represses DU145 prostate cancer tumorigenesis in a SUMOylation-dependent manner. Ectopic WWOX was shown to associate with SUMO2/3 or E2 Ubc9. Furthermore, we revealed that WWOX SUMOylation was promoted by E3 ligase polycomb2 (Pc2), and that WWOX associated with Pc2. Meanwhile, anisomycin-induced activator protein-1 (AP-1) activity was markedly diminished by co-expression of SUMO and WWOX. Also, WWOX wild type (WT), but not WWOX SUMO mutant (K176A) markedly reduced both DU145 prostate cancer cell proliferation and xenograft tumorigenesis. Collectively, our findings demonstrate that SUMO modification of WWOX is essential for its suppressive activity for DU145 prostate cancer tumorigenesis.