Therapeutic targeting of CBP/β-catenin signaling reduces cancer stem-like population and synergistically suppresses growth of EBV-positive nasopharyngeal carcinoma cells with cisplatin. Sci Rep. 2015;5:9979. [PMID: 25897700 PMCID: PMC4404684 DOI: 10.1038/srep09979]

Precision medicine in nasopharyngeal carcinoma: comprehensive review of past, present, and future prospect

Nasopharyngeal carcinoma (NPC) is an aggressive malignancy with high propensity for lymphatic spread and distant metastasis. It is prominent as an endemic malignancy in Southern China and Southeast Asia regions. Studies on NPC pathogenesis mechanism in the past decades such as through Epstein Barr Virus (EBV) infection and oncogenic molecular aberrations have explored several potential targets for therapy and diagnosis. The EBV infection introduces oncoviral proteins that consequently hyperactivate many promitotic pathways and block cell-death inducers. EBV infection is so prevalent in NPC patients such that EBV serological tests were used to diagnose and screen NPC patients. On the other hand, as the downstream effectors of oncogenic mechanisms, the promitotic pathways can potentially be exploited therapeutically. With the apparent heterogeneity and distinct molecular aberrations of NPC tumor, the focus has turned into a more personalized treatment in NPC. Herein in this comprehensive review, we depict the current status of screening, diagnosis, treatment, and prevention in NPC. Subsequently, based on the limitations on those aspects, we look at their potential improvements in moving towards the path of precision medicine. The importance of recent advances on the key molecular aberration involved in pathogenesis of NPC for precision medicine progression has also been reported in the present review. Besides, the challenge and future outlook of NPC management will also be highlighted.

Interplay between EZH2/β-catenin in stemness of cisplatin-resistant HNSCC and their role as therapeutic targets

The Wnt/β-catenin signaling pathway is associated with the regulation of cancer stem cells, and it can be driven by epigenetic modifications. Here, we aim to identify epigenetic modifications involved in the control of the Wnt/β-catenin signaling and investigate the role of this pathway in the accumulation of cancer stem cells (CSC) and chemoresistance of Head and Neck Squamous Cell Carcinoma (HNSCC). Quantitative-PCR, western blot, shRNA assay, viability assay, flow cytometry assay, spheres formation, xenograft model, and chromatin immunoprecipitation were employed to evaluate the Wnt/β-catenin pathway and EZH2 in wild-type and chemoresistant oral carcinoma cell lines, and in the populations of CSC and non-stem cells. We demonstrated that β-catenin and EZH2 were accumulated in cisplatin-resistant and CSC population. The upstream genes of the Wnt/β-catenin signaling (APC and GSK3β) were decreased, and the downstream gene MMP7 was increased in the chemoresistant cell lines. The inhibition of β-catenin and EZH2 combined effectively decreased the CSC population in vitro and reduced the tumor volume and CSC population in vivo. EZH2 inhibition increased APC and GSK3β, and the Wnt/β-catenin inhibition reduced MMP7 levels. In contrast, EZH2 overexpression decreased APC and GSK3β and increased MMP7. EZH2 and β-catenin inhibitors sensitized chemoresistant cells to cisplatin. EZH2 and H3K27me3 bounded the promoter of APC, leading to its repression. These results suggest that EZH2 regulates β-catenin by inhibiting the upstream gene APC contributing to the accumulation of cancer stem cells and chemoresistance. Moreover, the pharmacological inhibition of the Wnt/β-catenin combined with EZH2 can be an effective strategy for treating HNSCC.

Re-Sensitizing Cancer Stem Cells to Conventional Chemotherapy Agents

Cancer stem cells are found in many cancer types. They comprise a distinct subpopulation of cells within the tumor that exhibit properties of stem cells. They express a number of cell surface markers, such as CD133, CD44, ALDH, and EpCAM, as well as embryonic transcription factors Oct4, Nanog, and SOX2. CSCs are more resistant to conventional chemotherapy and can potentially drive tumor relapse. Therefore, it is essential to understand the molecular mechanisms that drive chemoresistance and to target them with specific therapy effectively. Highly conserved developmental signaling pathways such as Wnt, Hedgehog, and Notch are commonly reported to play a role in CSCs chemoresistance development. Studies show that particular pathway inhibitors combined with conventional therapy may re-establish sensitivity to the conventional therapy. Another significant contributor of chemoresistance is a specific tumor microenvironment. Surrounding stroma in the form of cancer-associated fibroblasts, macrophages, endothelial cells, and extracellular matrix components produce cytokines and other factors, thus creating a favorable environment and decreasing the cytotoxic effects of chemotherapy. Anti-stromal agents may potentially help to overcome these effects. Epigenetic changes and autophagy were also among the commonly reported mechanisms of chemoresistance. This review provides an overview of signaling pathway components involved in the development of chemoresistance of CSCs and gathers evidence from experimental studies in which CSCs can be re-sensitized to conventional chemotherapy agents across different cancer types.

Wnt Signaling in the Development of Bone Metastasis

Wnt signaling occurs through evolutionarily conserved pathways that affect cellular proliferation and fate decisions during development and tissue maintenance. Alterations in these highly regulated pathways, however, play pivotal roles in various malignancies, promoting cancer initiation, growth and metastasis and the development of drug resistance. The ability of cancer cells to metastasize is the primary cause of cancer mortality. Bone is one of the most frequent sites of metastases that generally arise from breast, prostate, lung, melanoma or kidney cancer. Upon their arrival to the bone, cancer cells can enter a long-term dormancy period, from which they can be reactivated, but can rarely be cured. The activation of Wnt signaling during the bone metastasis process was found to enhance proliferation, induce the epithelial-to-mesenchymal transition, promote the modulation of the extracellular matrix, enhance angiogenesis and immune tolerance and metastasize and thrive in the bone. Due to the complexity of Wnt pathways and of the landscape of this mineralized tissue, Wnt function during metastatic progression within bone is not yet fully understood. Therefore, we believe that a better understanding of these pathways and their roles in the development of bone metastasis could improve our understanding of the disease and may constitute fertile ground for potential therapeutics.

A miRNA-Based Prognostic Model to Trace Thyroid Cancer Recurrence

Simple Summary

Some thyroid tumors elected for surveillance remain indolent, while others progress. The mechanism responsible for this difference is poorly understood, making it challenging to devise patient surveillance plans. Early prediction is important for tailoring treatment and follow-up in high-risk patients. The aim of our study was to identify predictive markers for progression. We leveraged a highly sensitive test that accurately predicts which thyroid nodules are more likely to develop lymph node metastasis, thereby improving care and outcomes for cancer patients.

Abstract

Papillary thyroid carcinomas (PTCs) account for most endocrine tumors; however, screening and diagnosing the recurrence of PTC remains a clinical challenge. Using microRNA sequencing (miR-seq) to explore miRNA expression profiles in PTC tissues and adjacent normal tissues, we aimed to determine which miRNAs may be associated with PTC recurrence and metastasis. Public databases such as TCGA and GEO were utilized for data sourcing and external validation, respectively, and miR-seq results were validated using quantitative real-time PCR (qRT-PCR). We found miR-145 to be significantly downregulated in tumor tissues and blood. Deregulation was significantly related to clinicopathological features of PTC patients including tumor size, lymph node metastasis, TNM stage, and recurrence. In silico data analysis showed that miR-145 can negatively regulate multiple genes in the TC signaling pathway and was associated with cell apoptosis, proliferation, stem cell differentiation, angiogenesis, and metastasis. Taken together, the current study suggests that miR-145 may be a biomarker for PTC recurrence. Further mechanistic studies are required to uncover its cellular roles in this regard.

β-catenin inhibitors ICG-001 and pyrvinium sensitize bortezomib-resistant multiple myeloma cells to bortezomib

Although bortezomib (BTZ) displays efficacy in treating multiple myeloma (MM), BTZ resistance in MM patients has been reported. Meanwhile, treating BTZ resistant MM cells with β-catenin inhibitors have demonstrated the ability to reserve BTZ resistance. Thus, the present study aimed to investigate the synergistic effect of the β-catenin inhibitors, ICG-001 and pyrvinium (PP), with BTZ in the treatment of BTZ-resistant MM cells. Different concentrations of ICG-001 (0–32 µM) or PP (0–32 nM) were used to treat the BTZ-resistant RPMI-8226 (RPMI-8226BR) and BTZ-resistant KMS-11 (KMS-11BR) cell lines, followed by a BTZ combination treatment. Subsequently, cell viability and apoptosis in these two cell lines were determined by CCK-8 assay and flow cytometry, respectively. The proteins involved in the Wnt/β-catenin signaling pathway were detected using western blotting. The Wnt/β-catenin signaling pathway was activated in the RPMI-8226BR and the KMS-11BR cells. In addition, the cell viability of RPMI-8226BR and KMS-11BR cells were decreased following β-catenin inhibitor (ICG-001 and PP) treatment alone. Furthermore, the β-catenin inhibitors, ICG-001 and PP, plus BTZ combination treatment revealed a notable decrease in cell viability and a marked increase in cell apoptosis rate, compared with that in cells treated with ICG-001, PP or BTZ alone in the RPMI-8226BR and KMS-11BR cell lines. In conclusion, the β-catenin inhibitors, ICG-001 and PP not only increased apoptosis, but also sensitized BTZ-resistant MM cells to BTZ, indicating their potential therapeutic application in MM.

The CBP/β-Catenin Antagonist, ICG-001, Inhibits Tumor Metastasis via Blocking of the miR-134/ITGB1 Axis-Mediated Cell Adhesion in Nasopharyngeal Carcinoma

Simple Summary

Metastatic nasopharyngeal carcinoma (NPC) is incurable and remains the main cause of NPC death. Our previous studies found that the CBP/β-catenin Wnt antagonist, IGC-001, could inhibit the primary tumor formation of NPC tumor cells. Here, we further explored the anti-metastatic activity of ICG-001. We started by screening a panel of microRNAs that are related to epithelial–mesenchymal transition and cancer stem cell phenotypes; both properties can contribute to tumor metastasis. MicroRNA-134 was found to be consistently upregulated by ICG-001. The role of miR-134 in NPC is largely unknown but some studies found an association between low expression of miR-134 and poor prognosis. We examined the role of miR-134 in NPC with both in vitro and in vivo models and found that miR-134 could inhibit cancer cell adhesion, migration, and invasion. Our study provided a functional explanation for the poor prognosis observed in NPC patients with low or loss of miR-134 expression in their tumors and showed that modulation of the Wnt signaling by ICG-001 could effectively inhibit NPC metastasis via the miR-134/ITGB1 axis.

Abstract

Nasopharyngeal carcinoma (NPC) is an Epstein–Barr virus (EBV)-associated malignancy ranking as the 23rd most common cancer globally, while its incidence rate ranked the 9th in southeast Asia. Tumor metastasis is the dominant cause for treatment failure in NPC and metastatic NPC is yet incurable. The Wnt/β-catenin signaling pathway plays an important role in many processes such as cell proliferation, differentiation, epithelial–mesenchymal transition (EMT), and self-renewal of stem cells and cancer stem cells (CSCs). Both the EMT process and CSCs are believed to play a critical role in cancer metastasis. We here investigated whether the specific CBP/β-catenin Wnt antagonist, IGC-001, affects the metastasis of NPC cells. We found that ICG-001 treatment could reduce the adhesion capability of NPC cells to extracellular matrix and to capillary endothelial cells and reduce the tumor cell migration and invasion, events which are closely associated with distant metastasis. Through a screening of EMT and CSC-related microRNAs, it was found that miR-134 was consistently upregulated by ICG-001 treatment in NPC cells. Very few reports have mentioned the functional role of miR-134 in NPC, except that the expression was found to be downregulated in NPC. Transient transfection of miR-134 into NPC cells reduced their cell adhesion, migration, and invasion capability, but did not affect the growth of CSC-enriched tumor spheres. Subsequently, we found that the ICG-001-induced miR-134 expression resulting in downregulation of integrin β1 (ITGB1). Such downregulation reduced cell adhesion and migration capability, as demonstrated by siRNA-mediated knockdown of ITGB1. Direct targeting of ITGB1 by miR-134 was confirmed by the 3′-UTR luciferase assay. Lastly, using an in vivo lung metastasis assay, we showed that ICG-001 transient overexpression of miR-134 or stable overexpression of miR-134 could significantly reduce the lung metastasis of NPC cells. Taken together, we present here evidence that modulation of Wnt/β-catenin signaling pathway could inhibit the metastasis of NPC through the miR-134/ITGB1 axis.

Regulation of epithelial-mesenchymal transition by protein lysine acetylation

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

Involvement of activator protein-1 family members in β-catenin and p300 association on the genome of PANC-1 cells

Wnt/β-catenin is believed to regulate different sets of genes with different coactivators, cAMP response element-binding protein (CREB)-binding protein (CBP) or p300. However, the factors that determine which coactivators act on a particular promoter remain elusive. ICG-001 is a specific inhibitor for β-catenin/CBP but not for β-catenin/p300. By taking advantage of the action of ICG-001, we sought to investigate regulatory mechanisms underlying β-catenin coactivator usage in human pancreatic carcinoma PANC-1 cells through combinatorial analysis of chromatin immunoprecipitation-sequencing and RNA-sequencing. CBP and p300 preferentially bound to regions with the TCF motif alone and with both the TCF and AP-1 motifs, respectively. ICG-001 increased β-catenin binding to regions with both the TCF and AP-1 motifs, flanking the genes induced by ICG-001, concomitant with the increments of the p300 and AP-1 component c-JUN binding. Taken together, AP-1 possibly coordinates β-catenin coactivator usage in PANC-1 cells. These results would further our understanding of the canonical Wnt/β-catenin signaling divergence.

Pharmacological targeting of Sam68 functions in colorectal cancer stem cells

Cancer stem cells (CSCs) are documented to play a key role in tumorigenesis and therapy resistance. Despite significant progress in clinical oncology, CSC reservoirs remain elusive and difficult to eliminate. Reverse-turn peptidomimetics were characterized as disruptors of CBP/beta-Catenin interactions and represent a promising avenue to curb hyperactive canonical Wnt/beta-Catenin signaling in CSCs. Recent studies suggested Sam68 as a critical mediator of reverse-turn peptidomimetics response in CSC populations. Using computational and biochemical approaches we confirmed Sam68 as a primary target of reverse-turn peptidomimetics. Furthermore, we executed an in silico drug discovery pipeline to identify yet uncharacterized reverse-turn peptidomimetic structures displaying superior anti-CSC activity in transformed pluripotent and colorectal cancer cell models. Thus, we identified YB-0158 as a reverse-turn peptidomimetic small molecule with enhanced translational potential, altering key hallmarks of human colorectal CSCs in patient-derived ex vivo organoids and in vivo serial tumor transplantation.

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Sam68 is a direct protein target of reverse-turn peptidomimetic small molecules

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YB-0158 is a peptidomimetic structure with high predicted affinity for Sam68

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YB-0158 elicits a cancer-selective response impeding main cancer stem cell hallmarks

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YB-0158 blocks cancer stem cell activity in tumor organoids and in vivo systems

Wnt3a/β-Catenin/CBP Activation in the Progression of Cervical Intraepithelial Neoplasia

Piwil2 reprograms HPV-infected reserve cells in the cervix into tumor-initiated cells (TICs) and upregulates Wnt3a expression sequentially, which leads to cervical intraepithelial neoplasia (CIN) and ultimately squamous cell carcinoma (SCC). However, little is known regarding Wnt signaling in the maintenance of TIC stemness during the progression of cervical lesions. We herein investigated the expression of canonical Wnt3a signaling and related genes by microarray data set analysis and immunohistochemical (IHC) staining of samples obtained by biopsy of normal cervix, low- and high-grade CIN, and invasive SCC tissue. Array data analyzed by GEO2R showed higher expression levels of Wnt signaling and their target genes, significant upregulation of stemness-associated markers, and notably downregulated cell differentiation markers in CIN and SCC tissues compared with those in the normal cervix tissue. Further, Gene Set Enrichment Analysis (GSEA) revealed that Wnt pathway-related genes significantly enriched in SCC. IHC staining showed gradually increased immunoreactivity score of Wnt3a and CBP and notable translocation of β-catenin from the membrane to the cytoplasm and nucleus during the lesion progression. The intensity and proportion of P16, Ki67 and CK17 staining also increased with the progression of cervical lesions, whereas minimal to negative Involucrin expression was observed in CIN2/3 and SCC. Therefore, canonical Wnt signaling may contribute to the progression of CIN to SCC and may be a potential therapeutic target.

Targeting cancer stem cells for reversing therapy resistance: mechanism, signaling, and prospective agents

Cancer stem cells (CSCs) show a self-renewal capacity and differentiation potential that contribute to tumor progression and therapy resistance. However, the underlying processes are still unclear. Elucidation of the key hallmarks and resistance mechanisms of CSCs may help improve patient outcomes and reduce relapse by altering therapeutic regimens. Here, we reviewed the identification of CSCs, the intrinsic and extrinsic mechanisms of therapy resistance in CSCs, the signaling pathways of CSCs that mediate treatment failure, and potential CSC-targeting agents in various tumors from the clinical perspective. Targeting the mechanisms and pathways described here might contribute to further drug discovery and therapy.

Reversal of cisplatin sensitization and abrogation of cisplatin-enriched cancer stem cells in 5-8F nasopharyngeal carcinoma cell line through a suppression of Wnt/β-catenin-signaling pathway

Nasopharyngeal carcinoma (NPC) is one of the rare cancers in western countries but predominant in Southeast Asian countries including Thailand. One major cause for failure of NPC chemotherapeutic treatments is reportedly correlated with the elevation of cancer stem cell (CSC) fractions. Thus, this present study aims to investigate the effect of cisplatin (CDDP) treatment on the enrichment of cancer stem-like cells (CSCs) and its associated signaling pathway in EBV-negative NPC cells. Cisplatin-pretreated 5-8F NPC cells (5-8F CDDP) were first generated by treating the cells with 0.5 μM cisplatin for 48 h. After the instant treatment, 5-8F CDDP showed increased IC₅₀ values, demonstrating a decrease in CDDP sensitization. Besides, the proportion of NPC cells with cancer stem-like phenotypes comprising side population (SP), key stemness-related gene expressions including SOX2, ALDH1, CD24 was significantly enhanced. Additionally, 5-8F CDDP displayed the upregulation of β-catenin gene, suggesting its association with the CSC-initiating mechanism. Furthermore, a tankyrase inhibitor for Wnt/β-catenin pathway, XAV939, substantially reduced CSCs and retrieved the cisplatin sensitivity in 5-8F CDDP. This confirms that the Wnt/β-catenin signaling is accountable for rising of the CSC population in EBV-negative NPC. Finally, the combined treatment of CDDP and XAV939 exhibited lower 5-8F CDDP cell viability compared to the treatment of CDDP alone, suggesting the reversal of cisplatin sensitization. In conclusion, the enhancement of CSCs in 5-8F NPC cells caused by the instant cisplatin treatment is initially mediated through the upregulation of β-catenin and activation of Wnt/β-catenin signaling pathway. As a result, a primary chemotherapeutic treatment with closely monitoring the targeted Wnt/β-catenin signaling pathway could potentially prevent the development of CSCs and improve the treatment efficiency in NPC.

Pharmacologically Targeting the WNT/β-Catenin Signaling Cascade: Avoiding the Sword of Damocles

WNT/β-catenin signaling plays fundamental roles in numerous developmental processes and in adult tissue homeostasis and repair after injury, by controlling cellular self-renewal, activation, division, differentiation, movement, genetic stability, and apoptosis. As such, it comes as no surprise that dysregulation of WNT/β-catenin signaling is associated with various diseases, including cancer, fibrosis, neurodegeneration, etc. Although multiple agents that specifically target the WNT/β-catenin signaling pathway have been studied preclinically and a number have entered clinical trials, none has been approved by the FDA to date. In this chapter, we provide our insights as to the reason(s) it has been so difficult to safely pharmacologically target the WNT/β-catenin signaling pathway and discuss the significant efforts undertaken towards this goal.

Advances in targeted therapy mainly based on signal pathways for nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant epithelial carcinoma of the head and neck region which mainly distributes in southern China and Southeast Asia and has a crucial association with the Epstein-Barr virus. Based on epidemiological data, both incidence and mortality of NPC have significantly declined in recent decades grounded on the improvement of living standard and medical level in an endemic region, in particular, with the clinical use of individualized chemotherapy and intensity-modulated radiotherapy (IMRT) which profoundly contributes to the cure rate of NPC patients. To tackle the challenges including local recurrence and distant metastasis in the current NPC treatment, we discussed the implication of using targeted therapy against critical molecules in various signal pathways, and how they synergize with chemoradiotherapy in the NPC treatment. Combination treatment including targeted therapy and IMRT or concurrent chemoradiotherapy is presumably to be future options, which may reduce radiation or chemotherapy toxicities and open new avenues for the improvement of the expected functional outcome for patients with advanced NPC.

Role of miR-96/EVI1/miR-449a Axis in the Nasopharyngeal Carcinoma Cell Migration and Tumor Sphere Formation

The Wnt signaling pathway is one of the major signaling pathways used by cancer stem cells (CSC). Ecotropic Viral Integration Site 1 (EVI1) has recently been shown to regulate oncogenic development of tumor cells by interacting with multiple signaling pathways, including the Wnt signaling. In the present study, we found that the Wnt modulator ICG-001 could inhibit the expression of EVI1 in nasopharyngeal carcinoma (NPC) cells. Results from loss-of-function and gain-of-function studies revealed that EVI1 expression positively regulated both NPC cell migration and growth of CSC-enriched tumor spheres. Subsequent studies indicated ICG-001 inhibited EVI1 expression via upregulated expression of miR-96. Results from EVI1 3′UTR luciferase reporter assay confirmed that EVI1 is a direct target of miR-96. Further mechanistic studies revealed that ICG-001, overexpression of miR-96, or knockdown of EVI1 expression could restore the expression of miR-449a. The suppressive effect of miR-449a on the cell migration and tumor sphere formation was confirmed in NPC cells. Taken together, the miR-96/EVI1/miR-449a axis is a novel pathway involved in ICG-001-mediated inhibition of NPC cell migration and growth of the tumor spheres.

MiR-145 in cancer therapy resistance and sensitivity: A comprehensive review

MircoRNA (miRNA) are a group of small, non–coding, regulatory RNA with an average length of approximately 22 nucleotides, which mostly modulate gene expression post–transcriptionally through complementary binding to the 3ʹ‐untranslated region (3ʹ‐UTR) of multiple target genes. Emerging evidence has shown that miRNA are frequently dysregulated in a variety of human malignancies. Among them, microRNA‐145 (miR‐145) has been increasingly identified as a critical suppressor of carcinogenesis and therapeutic resistance. Resistance to tumor therapy is a challenge in cancer treatment due to the daunting range of resistance mechanisms. We reviewed the status quo of recent advancements in the knowledge of the functional role of miR‐145 in therapeutic resistance and the tumor microenvironment. It may serve as an innovative biomarker for therapeutic response and cancer prognosis.

MiR-34a Inhibits Cell Proliferation and Induces Apoptosis in Human Nasopharyngeal Carcinoma by Targeting lncRNA MCM3AP-AS1

Introduction

MCM3AP-AS1 has been characterized as an oncogenic lncRNA in several types of cancer, while its role in nasopharyngeal carcinoma (NPC) is unknown. This study aimed to investigate the role of MCM3AP-AS1 in NPC.

Patients and Methods

Paired NPC tissues and non-tumor tissues were collected from 55 NPC patients. Expression of MCM3AP-AS1 and miR-34a in paired tissues was analyzed by RT-qPCR. Interactions between MCM3AP-AS1 and miR-34a were analyzed by overexpression experiments. The roles of MCM3AP-AS1 and miR-34a in regulating NPC cell proliferation and apoptosis were explored by cell proliferation assay and cell apoptosis assay, respectively.

Results

Our bioinformatics analysis showed that MCM3AP-AS1 may be targeted by miR-34a, which is a well-studied tumor suppressor miRNA. In this study, we showed that miR-34a was downregulated and MCM3AP-AS1 was upregulated in NPC. An inverse correlation between the expression of MCM3AP-AS1 and miR-34a was found across NPC tissue samples. High expression level of MCM3AP-AS1 and low levels of miR-34a in NPC tissues predicted the poor survival. In NPC cells, overexpression of MCM3AP-AS1 did not affect the expression of miR34a, while overexpression of miR-34a led to downregulated MCM3AP-AS1. Cell proliferation and apoptosis assay showed that overexpression of miR-34a reduced the enhancing effects of overexpressing MCM3AP-AS1 on cell proliferation and the inhibitory effects on cell apoptosis.

Conclusion

MiR-34a inhibits cell proliferation and induces apoptosis in human NPC by targeting MCM3AP-AS1.

Cancer stem cells in Epstein-Barr virus-associated gastric carcinoma

Cancer stem cells (CSCs) play a decisive role in the development and progression of cancer. To investigate CSCs in Epstein-Barr virus (EBV)-associated carcinoma (EBVaGC), we screened previously reported stem cell markers of gastric cancer in EBV-infected gastric cancer cell lines (TMK1 and NUGC3) and identified CD44v6v9 double positive cells as candidate CSCs. CD44v6/v9^+/+ cells were sorted from EBVaGC cell line (SNU719) cells and EBV-infected TMK1 cells and these cell populations showed high spheroid-forming ability and tumor formation in SCID mice compared with the respective CD44v6/v9^-/- cells. Sphere-forming ability was dependent on the nuclear factor-κB (NF-κB) signaling pathway, which was confirmed by decrease of sphere formation ability under BAY 11-7082. Small interfering RNA knockdown of latent membrane protein 2A (LMP2A), one of the latent gene products of EBV infection, decreased spheroid formation in SNU719 cells. Transfection of the LMP2A gene increased the sphere-forming ability of TMK1 cells, which was mediated through NF-κB signaling. Together, these results indicate that CD44v6v9^+/+ cells are CSCs in EBVaGC that are maintained through the LMP2A/NF-κB pathway. Future studies should investigate CD44v6/v9^+/+ cells in normal and neoplastic gastric epithelium to prevent and treat this specific subtype of gastric cancer infected with EBV.

LncRNA SNHG7 promotes the proliferation of nasopharyngeal carcinoma by miR-514a-5p/ELAVL1 axis

Background

Nasopharyngeal carcinoma (NPC), with distinct geographical distribution, has gathered public attention. Despite that radiotherapy and chemotherapy are applied to treat NPC, cell metastasis still cannot be avoided. Numerous works have elucidated that lncRNAs are essential players in the development of multiple cancers. LncRNA SNHG7 has been reported as a contributing factor in the occurrence of certain cancers, but its mechanism in NPC deserves further investigation. The purpose of the study is to figure out the role and molecular regulation mechanism of SNHG7 in NPC.

Methods

The role of SNHG7 in NPC was verified by CCK-8, colony formation, EdU staining, western blot and capase-3 assays. The interactions between SNHG7/ELAVL1 and miR-514a-5p were confirmed by RNA pull down, RT-qPCR, RIP and luciferase reporter assays.

Results

SNHG7 was upregulated in NPC cells, and absence of SNHG7 suppressed cell proliferation as well as promoted cell apoptosis in NPC. Furthermore, SNHG7 was confirmed to bind with miR-514a-5p and negatively modulate miR-514a-5p expression. Besides, miR-514a-5p was found to be able to bind with ELAVL1 and negatively regulate ELAVL1 mRNA and protein expressions. In the end, rescue assays demonstrated that the miR-514a-5p deficiency restored the NPC progression inhibited by SNHG7 silence, and ELAVL1 partly counteracted the restoration caused by miR-514a-5p inhibitor in HNE1 cells.

Conclusions

LncRNA SNHG7 promotes the proliferation and migration of nasopharyngeal carcinoma by miR-514a-5p/ ELAVL1 axis.

Interaction between the scaffold proteins CBP by IQGAP1 provides an interface between gene expression and cytoskeletal activity

Crosstalk between cellular pathways is often mediated through scaffold proteins that function as platforms for the assembly of signaling complexes. Based on yeast two-hybrid analysis, we report here the interaction between two complex scaffold proteins, CREB-binding protein (CBP) and the Ras GTPase-activating-like protein 1 (IQGAP1). Dissection of the interaction between the two proteins reveals that the central, thus far uncharacterized, region of IQGAP1 interacts with the HAT domain and the C-terminal intrinsically disordered region of CBP (termed ID5). Structural analysis of ID5 by solution NMR spectroscopy and SAXS reveals the presence of two regions with pronounced helical propensity. The ID5 region(s) involved in the interaction of nanomolar affinity were delineated by solution NMR titrations and pull-down assays. Moreover, we found that IQGAP1 acts as an inhibitor of the histone acetyltransferase (HAT) activity of CBP. In in vitro assays, the CBP-binding region of IQGAP1 positively and negatively regulates the function of HAT proteins of different families including CBP, KAT5 and PCAF. As many signaling pathways converge on CBP and IQGAP1, their interaction provides an interface between transcription regulation and the coordination of cytoskeleton. Disruption or alteration of the interaction between these scaffold proteins may lead to cancer development or metastatic processes, highlighting the importance of this interaction.

Curcumin Enhances Radiosensitization of Nasopharyngeal Carcinoma via Mediating Regulation of Tumor Stem-like Cells by a CircRNA Network

Circular RNAs (circRNAs) are involved in cancer development via inhibition of miRNAs, which are associated with differentiation, proliferation, migration, and carcinogenicity. Curcumin has antioxidant and anti-cancer properties, and it has also been used as a radiosensitizer. In this study, we explored the potential relationships among curcumin, circRNAs, and nasopharyngeal carcinoma (NPC). We compared the differences in circRNA levels in NPC cell lines after radiotherapy and after treatment with curcumin, using a high-throughput microarray. Further, a circRNA-miRNA-mRNA interaction network between radiation resistance NPC cell lines and tumor stem cells was constructed by applying bioinformatics. Finally, it was demonstrated by reverse transcription-quantitative polymerase chain reaction assay and wound healing assay that curcumin could enhance radiosensitization of NPC cell lines via mediating regulation of tumor stem-like cells by the "hsa_circRNA_102115"-"hsa-miR-335-3p"-"MAPK1" interaction network.

USP12 translocation maintains interferon antiviral efficacy by inhibiting CBP acetyltransferase activity

CREB-binding protein (CBP) participates in numerous transcription events. However, cell-intrinsic inhibitors of CBP are poorly defined. Here, we found that cellular USP12 interacts with the HAT domain of CBP and inhibits CBP’s acetyltransferase activity. Interestingly, USP12 positively regulates interferon (IFN) antiviral signaling independently of its deubiquitinase activity. Furthermore, we found that in IFN signaling USP12 translocates from the cytoplasm to the nucleus. The decrease in cytoplasmic USP12 facilitates CBP-induced acetylation and activation of IFN signaling proteins in the cytoplasm. Moreover, USP12 accumulation in the nucleus blocks CBP-induced acetylation of phosphorylated STAT1 (p-STAT1) and therefore inhibits the dephosphorylation effects of TCPTP on p-STAT1, which finally maintains nuclear p-STAT1 levels and IFN antiviral efficacy. USP12 nuclear translocation extends our understanding of the regulation of the strength of IFN antiviral signaling. Our study uncovers a cell-intrinsic regulation of CBP acetyltransferase activity and may provide potential strategies for IFN-based antiviral therapy.

Activated p-STAT1 is a determinant for the strength of IFN antiviral signaling. We and other groups have demonstrated that activated p-STAT1 is regulated by multiple protein post-translational modifications, including phosphorylation, acetylation and ubiquitination. In this study, we revealed that CBP-mediated acetylation regulation of p-STAT1 is modulated by the deubiquitinase USP12 in a deubiquitinase activity-independent manner. USP12 translocates into the nucleus in IFN signaling, which critically regulates nuclear p-STAT1 levels and IFN antiviral activity by inhibiting CBP’s acetyltransferase activity. Importantly, we demonstrated that USP12 is a cell-intrinsic inhibitor of the acetyltransferase CBP. These findings promote the understanding of delicate regulation of both CBP-mediated acetylation and IFN antiviral signaling.

Pharmacological Modulation of the Wnt/β-Catenin Pathway Inhibits Proliferation and Promotes Differentiation of Long-Lived Memory CD4+ T Cells in Antiretroviral Therapy-Suppressed Simian Immunodeficiency Virus-Infected Macaques

The major obstacle to human immunodeficiency type 1 virus (HIV-1) eradication is a reservoir of latently infected cells that persists despite long-term antiretroviral therapy (ART) and is maintained through cellular proliferation. Long-lived memory CD4+ T cells with high self-renewal capacity, such as central memory (CM) T cells and stem cell memory (SCM) T cells, are major contributors to the viral reservoir in HIV-infected individuals on ART. The Wnt/β-catenin signaling pathway regulates the balance between self-renewal and differentiation of SCM and CM T cells, and pharmacological manipulation of this pathway offers an opportunity to interfere with the proliferation of latently infected cells. Here, we evaluated in vivo a novel approach to inhibit self-renewal of SCM and CM CD4+ T cells in the rhesus macaque (RM) model of simian immunodeficiency (SIV) infection. We used an inhibitor of the Wnt/β-catenin pathway, PRI-724, that blocks the interaction between the coactivator CREB-binding protein (CBP) and β-catenin, resulting in the cell fate decision to differentiate rather than proliferate. Our study shows that PRI-724 treatment of ART-suppressed SIVmac251-infected RMs resulted in decreased proliferation of SCM and CM T cells and modified the SCM and CM CD4+ T cell transcriptome toward a profile of more differentiated memory T cells. However, short-term treatment with PRI-724 alone did not significantly reduce the size of the viral reservoir. This work demonstrates for the first time that stemness pathways of long-lived memory CD4+ T cells can be pharmacologically modulated in vivo, thus establishing a novel strategy to target HIV persistence.IMPORTANCE Long-lasting CD4+ T cell subsets, such as central memory and stem cell memory CD4+ T cells, represent critical reservoirs for human immunodeficiency virus (HIV) persistence despite suppressive antiretroviral therapy. These cells possess stem cell-like properties of enhanced self-renewal/proliferation, and proliferation of latently infected memory CD4+ T cells plays a key role in maintaining the reservoir over time. Here, we evaluated an innovative strategy targeting the proliferation of long-lived memory CD4+ T cells to reduce viral reservoir stability. Using the rhesus macaque model, we tested a pharmacological inhibitor of the Wnt/β-catenin signaling pathway that regulates T cell proliferation. Our study shows that administration of the inhibitor PRI-724 decreased the proliferation of SCM and CM CD4+ T cells and promoted a transcriptome enriched in differentiation genes. Although the viral reservoir size was not significantly reduced by PRI-724 treatment alone, we demonstrate the potential to pharmacologically modulate the proliferation of memory CD4+ T cells as a strategy to limit HIV persistence.

LncRNA GAS5 facilitates nasopharyngeal carcinoma progression through epigenetically silencing PTEN via EZH2

Increasing evidence demonstrated that long non-coding RNA growth-arrest-specific transcript 5 (GAS5) serves as a critical regulator in cancer development and progression. However, its function and mechanism in nasopharyngeal carcinoma (NPC) is still not well elucidated. In this study, we investigate the functional role as well as the molecular mechanism of GAS5 in NPC progression. Our results indicated that GAS5 expression was elevated in NPC tissues and cells. High GAS5 expression was correlated with poor prognosis of NPC patients. GAS5 knockdown suppressed proliferation, migration and invasion, and induced apoptosis in NPC cells. Moreover, GAS5 could epigenetically suppress PTEN expression via recruiting enhancer of zeste homolog 2 (EZH2). PTEN knockdown could reverse the inhibitory effect of GAS5 inhibition on NPC progression. Furthermore, GAS5 knockdown suppressed the tumor growth in vivo. In summary, knockdown of GAS5 repressed proliferation, migration and invasion, and promoted apoptosis in NPC through epigenetically silencing PTEN via recruiting EZH2.

The anti-tumor function of the IKK inhibitor PS1145 and high levels of p65 and KLF4 are associated with the drug resistance in nasopharyngeal carcinoma cells

We and others have previously shown that the canonical nuclear factor kappa-B (NF-κB) pathway is essential to nasopharyngeal carcinoma (NPC) tumor development and angiogenesis, suggesting that the NF-κB pathway, including its upstream modulators and downstream effectors, are potential therapeutic targets for NPC. The inhibitor of upstream IκB kinase (IKK), PS1145, is a small molecule which can specifically inhibit the IκB phosphorylation and degradation and the subsequent nuclear translocation of NF-κB. The present study aims to determine the anti-tumor activity of PS1145 on NPC. Our results showed that PS1145 significantly inhibited the growth of tumorigenic NPC cell lines, but not in the normal nasopharyngeal epithelial cell line. Results in the in vivo study showed that low concentration of PS1145 (3 mg/kg) could significantly suppress the subcutaneous tumor formation in the nude mice bearing NPC xenografts. Apparent adverse effects were not observed in the animal study. Drug resistance against PS1145 seems to be associated with the increased levels of active NF-kB p65 and change of expression levels of kruppel-like factor 4. As can be seen, PS1145 appears to be a safe agent for animal experiments and its effects are tumor-specific, and the proteins associated with the drug resistance of PS1145 are implied.

Inhibition of CBP/β-catenin and porcupine attenuates Wnt signaling and induces apoptosis in head and neck carcinoma cells

PURPOSE

Activation of the Wnt pathway contributes to the development of head and neck squamous cell carcinomas (HNSCC) and its inhibition has recently emerged as a promising therapeutic strategy. Here, we aimed at identifying suitable molecular targets for down-regulation of canonical Wnt signaling in HNSCC cells.

METHODS

Candidate target genes (PORCN, WNT3A, FZD2, FZD5, LRP5, DVL1, CIP2A, SET, KDM1A, KDM4C, KDM6A, CBP, CARM1, KMT2A, TCF7, LEF1, PYGO1, XIAP) were silenced using siRNA and selected targets were subsequently blocked using small molecule inhibitors. The effect of this treatment on the expression of β-catenin-dependent genes was assessed by qRT-PCR. The effect of the inhibitors on cell viability was evaluated using a resazurin assay in HNSCC-derived cell lines. A luciferase reporter assay was used for confirmation of the inhibition of Wnt-dependent gene expression. Cell migration was evaluated using a scratch wound healing assay. Cytometric analysis of propidium iodide stained cells was used for cell cycle distribution evaluation, whereas cytometric analysis of caspase 3/7 activity was used for apoptosis induction evaluation.

RESULTS

We found that inhibition of Porcupine and CBP/β-catenin interaction by IWP-2 and PRI-724, respectively, most strongly affected β-catenin-dependent gene expression in HNSCC cells. These inhibitors also induced apoptosis and affected HNSCC cell migration.

CONCLUSIONS

Targeting Porcupine or the CBP/β-catenin interaction seems to be an effective strategy for the inhibition of canonical Wnt signaling in HNSCC cells. Further studies are required to confirm the possible therapeutic effect of IWP-2 and PRI-724 in HNSCC.

Nobiletin induces growth inhibition and apoptosis in human nasopharyngeal carcinoma C666-1 cells through regulating PARP-2/SIRT1/AMPK signaling pathway

BACKGROUND/AIM

Nobiletin, a major polymethoxyflavones (PMFs) from citri reticulatae pericarpium (CRP), can inhibit several forms of cancer proliferation. However, the effects of nobiletin on nasopharyngeal carcinoma (NPC) C666-1 cells remain largely unknown.

MATERIALS AND METHODS

Cell counting kit 8 (CCK8) assay was used to measure cell vitality. Flow cytometry was performed to measure the apoptosis rate. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analysis were applied to determine the expression of mRNA and protein, respectively.

RESULTS

We showed that the proliferation rate of C666-1 cells was inhibited and the apoptosis rate was raised after treating with nobiletin. Moreover, nobiletin inhibited the expression of poly(ADP-ribose)polymerase-2 (PARP-2), and the tumor suppression effect of nobiletin on C666-1 is associated with PARP-2-dependent pathway.

CONCLUSION

We demonstrated for the first time that nobiletin inhibited the growth of C666-1 cells, which may be relative to its regulation on PARP-2/SIRT1/AMPK signaling pathway. Our result implied that nobiletin may serve as a strategy to treat nasopharyngeal carcinoma.

CBP/β-Catenin/FOXM1 Is a Novel Therapeutic Target in Triple Negative Breast Cancer

Background: Triple negative breast cancers (TNBCs) are an aggressive BC subtype, characterized by high rates of drug resistance and a high proportion of cancer stem cells (CSC). CSCs are thought to be responsible for tumor initiation and drug resistance. cAMP-response element-binding (CREB) binding protein (CREBBP or CBP) has been implicated in CSC biology and may provide a novel therapeutic target in TNBC. Methods: RNA Seq pre- and post treatment with the CBP-binding small molecule ICG-001 was used to characterize CBP-driven gene expression in TNBC cells. In vitro and in vivo TNBC models were used to determine the therapeutic effect of CBP inhibition via ICG-001. Tissue microarrays (TMAs) were used to investigate the potential of CBP and associated proteins as biomarkers in TNBC. Results: The CBP/ß-catenin/FOXM1 transcriptional complex drives gene expression in TNBC and is associated with increased CSC numbers, drug resistance and poor survival outcome. Targeting of CBP/β-catenin/FOXM1 with ICG-001 eliminated CSCs and sensitized TNBC tumors to chemotherapy. Immunohistochemistry of TMAs demonstrated a significant correlation between FOXM1 expression and TNBC subtype. Conclusion: CBP/β-catenin/FOXM1 transcriptional activity plays an important role in TNBC drug resistance and CSC phenotype. CBP/β-catenin/FOXM1 provides a molecular target for precision therapy in triple negative breast cancer and could form a rationale for potential clinical trials.

Emerging Role of Histone Acetyltransferase in Stem Cells and Cancer

Protein acetylation is one of the most important posttranslational modifications catalyzed by acetyltransferases and deacetylases, through the addition and removal of acetyl groups to lysine residues. Lysine acetylation can affect protein-nucleic acid or protein-protein interactions and protein localization, transport, stability, and activity. It regulates the function of a large variety of proteins, including histones, oncoproteins, tumor suppressors, and transcription factors, thus representing a crucial regulator of several biological processes with particular prominent roles in transcription and metabolism. Thus, it is unsurprising that alteration of protein acetylation is involved in human disease, including metabolic disorders and cancers. In this context, different hematological and solid tumors are characterized by deregulation of the protein acetylation pattern as a result of genetic or epigenetic changes. The imbalance between acetylation and deacetylation of histone or nonhistone proteins is also involved in the modulation of the self-renewal and differentiation ability of stem cells, including cancer stem cells. Here, we summarize a combination of in vitro and in vivo studies, undertaken on a set of acetyltransferases, and discuss the physiological and pathological roles of this class of enzymes. We also review the available data on the involvement of acetyltransferases in the regulation of stem cell renewal and differentiation in both normal and cancer cell population.

The Wnt modulator ICG‑001 mediates the inhibition of nasopharyngeal carcinoma cell migration in vitro via the miR‑150/CD44 axis

The Wnt signaling pathway is known to serve an important role in the control of cell migration. The present study analyzed the mechanisms underlying the in vitro modulation of the migration of nasopharyngeal carcinoma (NPC) cells by the CREB‑binding protein/catenin antagonist and Wnt modulator ICG‑001. The results revealed that ICG‑001‑mediated inhibition of tumor cell migration involved downregulated mRNA and protein expression of the Wnt target gene cluster of differentiation (CD)44. It was also demonstrated that ICG‑001 downregulated the expression of CD44, and this effect was accompanied by restored expression of microRNA (miRNA)‑150 in various NPC cell lines. Using a CD44 3'‑untranslated region luciferase reporter assay, miR‑150 was confirmed to be a novel CD44‑targeting miRNA, which could directly target CD44 and subsequently regulate the migration of NPC cells. The present study provides further insight into the inhibition of tumor cell migration through the modulation of miRNA expression by the Wnt modulator ICG‑001.

Functional and genomic analyses reveal therapeutic potential of targeting β-catenin/CBP activity in head and neck cancer

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is an aggressive malignancy characterized by tumor heterogeneity, locoregional metastases, and resistance to existing treatments. Although a number of genomic and molecular alterations associated with HNSCC have been identified, they have had limited impact on the clinical management of this disease. To date, few targeted therapies are available for HNSCC, and only a small fraction of patients have benefited from these treatments. A frequent feature of HNSCC is the inappropriate activation of β-catenin that has been implicated in cell survival and in the maintenance and expansion of stem cell-like populations, thought to be the underlying cause of tumor recurrence and resistance to treatment. However, the therapeutic value of targeting β-catenin activity in HNSCC has not been explored.

METHODS

We utilized a combination of computational and experimental profiling approaches to examine the effects of blocking the interaction between β-catenin and cAMP-responsive element binding (CREB)-binding protein (CBP) using the small molecule inhibitor ICG-001. We generated and annotated in vitro treatment gene expression signatures of HNSCC cells, derived from human oral squamous cell carcinomas (OSCCs), using microarrays. We validated the anti-tumorigenic activity of ICG-001 in vivo using SCC-derived tumor xenografts in murine models, as well as embryonic zebrafish-based screens of sorted stem cell-like subpopulations. Additionally, ICG-001-inhibition signatures were overlaid with RNA-sequencing data from The Cancer Genome Atlas (TCGA) for human OSCCs to evaluate its association with tumor progression and prognosis.

RESULTS

ICG-001 inhibited HNSCC cell proliferation and tumor growth in cellular and murine models, respectively, while promoting intercellular adhesion and loss of invasive phenotypes. Furthermore, ICG-001 preferentially targeted the ability of subpopulations of stem-like cells to establish metastatic tumors in zebrafish. Significantly, interrogation of the ICG-001 inhibition-associated gene expression signature in the TCGA OSCC human cohort indicated that the targeted β-catenin/CBP transcriptional activity tracked with tumor status, advanced tumor grade, and poor overall patient survival.

CONCLUSIONS

Collectively, our results identify β-catenin/CBP interaction as a novel target for anti-HNSCC therapy and provide evidence that derivatives of ICG-001 with enhanced inhibitory activity may serve as an effective strategy to interfere with aggressive features of HNSCC.

Wnt signaling in bone metastasis: mechanisms and therapeutic opportunities

Bone metastasis frequently occurs in advanced cancer patients, who will develop osteogenic/osteolytic bone lesions in the late stage of the disease. Wnt signaling pathway, which is mainly grouped into the β-catenin dependent pathway and β-catenin independent pathway, is a well-organized cascade that has been reported to play important roles in a variety of physiological and pathological conditions, including bone metastasis. Regulation of Wnt signaling in bone metastasis involves multiple stages, including dissemination of primary tumor cells to bone, dormancy and outgrowth of metastatic tumor cells, and tumor-induced osteogenic and osteolytic bone destruction, suggesting the importance of Wnt signaling in bone metastasis pathology. In this review, we will introduce the involvement of Wnt signaling components in specific bone metastasis stages and summarize the promising Wnt modulators that have shown potential as bone metastasis therapeutics, in the hope to maximize the therapeutic opportunities of Wnt signaling for bone metastasis.

Immune Curbing of Cancer Stem Cells by CTLs Directed to NANOG

Cancer stem cells (CSCs) have been identified as the source of tumor growth and disease recurrence. Eradication of CSCs is thus essential to achieve durable responses, but CSCs are resistant to current anti-tumor therapies. Novel therapeutic approaches that specifically target CSCs will, therefore, be crucial to improve patient outcome. Immunotherapies, which boost the body's own immune system to eliminate cancerous cells, could be an alternative approach to target CSCs. Vaccines of dendritic cells (DCs) loaded with tumor antigens can evoke highly specific anti-tumor T cell responses. Importantly, DC vaccination also promotes immunological memory formation, paving the way for long-term cancer control. Here, we propose a DC vaccination that specifically targets CSCs. DCs loaded with NANOG peptides, a protein required for maintaining stem cell properties, could evoke a potent anti-tumor immune response against CSCs. We hypothesize that the resulting immunological memory will also control newly formed CSCs, thereby preventing disease recurrence.

Emerging Insights into Wnt/β-catenin Signaling in Head and Neck Cancer

Head and neck cancer presents primarily as head and neck squamous cell carcinoma (HNSCC), a debilitating malignancy fraught with high morbidity, poor survival rates, and limited treatment options. Mounting evidence indicates that the Wnt/β-catenin signaling pathway plays important roles in the pathobiology of HNSCC. Wnt/β-catenin signaling affects multiple cellular processes that endow cancer cells with the ability to maintain and expand immature stem-like phenotypes, proliferate, extend survival, and acquire aggressive characteristics by adopting mesenchymal traits. A central component of canonical Wnt signaling is β-catenin, which balances its role as a structural component of E-cadherin junctions with its function as a transcriptional coactivator of numerous target genes. Recent genomic characterization of head and neck cancer revealed that while β-catenin is not frequently mutated in HNSCC, its activity is unchecked by more common mutations in genes encoding upstream regulators of β-catenin, NOTCH1, FAT1, and AJUBA. Wnt/β-catenin signaling affects a wide range epigenetic and transcriptional activities, mediated by the interaction of β-catenin with different transcription factors and transcriptional coactivators and corepressors. Furthermore, Wnt/β-catenin functions in a network with many signaling and metabolic pathways that modulate its activity. In addition to its effects on tumor epithelia, β-catenin activity regulates the tumor microenvironment by regulating extracellular matrix remodeling, fibrotic processes, and immune response. These multifunctional oncogenic effects of β-catenin make it an attractive bona fide target for HNSCC therapy.

Activation of c-Jun/JNK signaling predicts poor prognosis in nasopharyngeal carcinoma

A significant proportion of patients with nasopharyngeal carcinoma (NPC) will develop regional relapse or distant metastasis after treatment. This present study evaluated the role of c-Jun/JNK signaling pathways in NPC and its relationship with prognosis. Our study enrolled 122 patients diagnosed with NPC and 136 chronic nasosinusitis patients. Immunohistochemistry was applied to detect positive expression of c-Jun, JNK, p-c-Jun, and p-JNK proteins. Receiver operating characteristic (ROC) curve was then adopted to assess the diagnostic value of c-Jun/JNK signaling pathways for NPC. Activated c-Jun/JNK signaling pathways were observed in NPC patients. Activation of c-Jun/JNK signaling was associated with TNM staging of NPC, as NPC patients with stage III-IV had higher positive expression rates of c-Jun, JNK, p-c-Jun, and p-JNK proteins compared to NPC patients with stage I-II. According to ROC curve results, areas under the curve of c-Jun, JNK, p-c-Jun, and p-JNK protein expression were 0.943, 0.968, 0.963, and 0.938, respectively. The 1-, 3-, and 5-year survival rates and mean survival times of dead patients were lower and shorter in patients with positive expressions of c-Jun, JNK, p-c-Jun, and p-JNK than those with negative expression (all P < 0.05). Overexpression of c-Jun/JNK is associated with development and progression of NPC, indicating that c-Jun/JNK serves as a predictive indicator for early diagnosis and prognosis of NPC.

Epstein-Barr virus infection and nasopharyngeal carcinoma

Epstein-Barr virus (EBV) is associated with multiple types of human cancer, including lymphoid and epithelial cancers. The closest association with EBV infection is seen in undifferentiated nasopharyngeal carcinoma (NPC), which is endemic in the southern Chinese population. A strong association between NPC risk and the HLA locus at chromosome 6p has been identified, indicating a link between the presentation of EBV antigens to host immune cells and NPC risk. EBV infection in NPC is clonal in origin, strongly suggesting that NPC develops from the clonal expansion of a single EBV-infected cell. In epithelial cells, the default program of EBV infection is lytic replication. However, latent infection is the predominant mode of EBV infection in NPC. The establishment of latent EBV infection in pre-invasive nasopharyngeal epithelium is believed to be an early stage of NPC pathogenesis. Recent genomic study of NPC has identified multiple somatic mutations in the upstream negative regulators of NF-κB signalling. Dysregulated NF-κB signalling may contribute to the establishment of latent EBV infection in NPC. Stable EBV infection and the expression of latent EBV genes are postulated to drive the transformation of pre-invasive nasopharyngeal epithelial cells to cancer cells through multiple pathways.This article is part of the themed issue 'Human oncogenic viruses'.

Correlations of the expressions of c-Jun and Egr-1 proteins with clinicopathological features and prognosis of patients with nasopharyngeal carcinoma

This study intended to explore the correlation of the expressions of c-Jun and Egr-1 proteins with clinicopathological features and prognosis of patients with nasopharyngeal carcinoma (NPC). From January 2008 to January 2011, 123 NPC patients and 59 patients with chronic rhinitis were enrolled in this study. Fresh NPC and normal nasopharynx tissue specimens were obtained during surgery. Immunohistochemistry (IHC) was adopted to determine the positive expressions of the c-Jun and Egr-1 proteins. A 5-year clinical follow-up was conducted on all NPC patients. The Kaplan-Meier survival curve and Cox regression model were used for survival analysis. Compared with normal nasopharynx tissues, c-Jun expression was up-regulated but Egr-1 expression was down-regulated in NPC tissues. NPC patients with stage T3-T4 or stage III-IV had higher positive rates of c-Jun expression than those with stage T1-T2 or stage I-II. However, the positive rates of Egr-1 expression was higher in patients with stage T1-T2 or stage III-IV than those with stage T3-T4 or stage I-II. The survival rate of NPC patients with high c-Jun expression was lower than those with low/negative c-Jun expression, while the survival rate of NPC patients with high Egr-1 expression was higher than those with low/negative Egr-1 expression. The Cox regression analysis revealed that stage T3-T4, high c-Jun expression, and low Egr-1 expression were risk factors for poor prognosis of NPC patients. In conclusion, our study suggests that the c-Jun and Egr-1 proteins can serve as novel potential biomarkers for the early diagnosis and prognosis prediction of NPC.

Wnt Signaling in Stem Cells and Cancer Stem Cells: A Tale of Two Coactivators

Wnt signaling in stem cells plays critical roles in development, normal adult physiology, and disease. In this chapter, we focus on the role of the Wnt signaling pathway in somatic stem cell biology and its critical role in normal tissue homeostasis and cancer. Wnt signaling can both maintain potency and initiate differentiation in somatic stem cells, depending on the cellular and environmental context. Based principally on studies from our lab, we will explain the dichotomous behavior of this signaling pathway in determining stem cell fate decisions, placing special emphasis on the interaction of β-catenin with either of the two highly homologous Kat3 coactivator proteins, CBP and p300. We will also discuss our results, both preclinical and clinical, demonstrating that small molecule modulators of the β-catenin/Kat3 coactivator interaction can be safely utilized to shift the balance between maintenance of potency and initiation of differentiation.

MALAT1/miR-124/Capn4 axis regulates proliferation, invasion and EMT in nasopharyngeal carcinoma cells

BACKGROUND

Long non-coding RNA MALAT1 (Metastasis-associated lung Adenocarcinoma transcript-1) has been demonstrated to play a critical role in the regulation of cancer progression and metastasis. However, little is known about MALAT1 in nasopharyngeal carcinoma (NPC) pathogenesis and progression.

METHODS

Quantitative real-time PCR (qRT-PCR) was conducted to measure the expression of MALAT1, miR-124 and Capn4 mRNA in NPC cell lines. The protein level of Capn4 was examined by western blot analysis. Cell proliferation was detected by MTT assay, trypan blue exclusion method and colony formation analysis. Cell invasion was determined by transwell chamber assay. Expression of EMT-related proteins was detected by western blot. The potential targets of MALAT1 and miR-124 were verified by target prediction and luciferase reporter assay.

RESULTS

MALAT1 and Capn4 were upregulated while miR-124 expression was downregulated in NPC cell lines. MALAT1 knockdown inhibited proliferation, invasion and EMT of NPC cells. Moreover, MALAT1 improved Capn4 expression by sponging miR-124. MALAT1 upregulation abated miR-124-induced repression on NPC cell proliferation, invasion and EMT. Furthermore, Capn4 overexpression reversed the inhibitory effect of MALAT1 silencing on proliferation, invasion and EMT of NPC cells.

CONCLUSION

MALAT1 promoted proliferation, invasion and EMT of NPC cells through de-repressing Capn4 by sponging miR-124. The present study revealed a novel MALAT1/miR-124/Capn4 regulatory axis in NPC, contributing to a better understanding of the NPC pathogenesis and providing a promising therapeutic target for NPC therapy.

CBP/Catenin antagonists: Targeting LSCs' Achilles heel

Cancer stem cells (CSCs), including leukemia stem cells (LSCs), exhibit self-renewal capacity and differentiation potential and have the capacity to maintain or renew and propagate a tumor/leukemia. The initial isolation of CSCs/LSCs was in adult myelogenous leukemia, although more recently, the existence of CSCs in a wide variety of other cancers has been reported. CSCs, in general, and LSCs, specifically with respect to this review, are responsible for initiation of disease, therapeutic resistance and ultimately disease relapse. One key focus in cancer research over the past decade has been the development of therapies that safely eliminate the LSC/CSC population. One major obstacle to this goal is the identification of key mechanisms that distinguish LSCs from normal endogenous hematopoietic stem cells. An additional daunting feature that has recently come to light with advances in next-generation sequencing and single-cell sequencing is the heterogeneity within leukemias/tumors, with multiple combinations of mutations, gain and loss of function of genes, and so on being capable of driving disease, even within the CSC/LSC population. The focus of this review/perspective is on our work in identifying and validating, in both chronic myelogenous leukemia and acute lymphoblastic leukemia, a safe and efficacious mechanism to target an evolutionarily conserved signaling nexus, which constitutes a common "Achilles heel" for LSCs/CSCs, using small molecule-specific CBP/catenin antagonists.

miR-124 suppresses proliferation and invasion of nasopharyngeal carcinoma cells through the Wnt/β-catenin signaling pathway by targeting Capn4

Background

Recent studies have demonstrated that microRNA 124 (miR-124) acts as a tumor suppressor in nasopharyngeal carcinoma (NPC); however, the exact molecular mechanism by which miR-124 exerts tumor suppression has not been well elucidated.

Materials and methods

We performed quantitative real-time PCR (qRT-PCR) to measure the expression of metastasis associated lung adenocarcinoma transcript 1, miR-124, and calpain small subunit 1 (Capn4) mRNAs in NPC cell lines. We also performed western blot analysis to detect the levels of Capn4. Furthermore, we performed MTT assay and transwell invasion assay to determine the proliferation and invasion ability of two NPC cell lines, namely, HONE1 and CNE2 cells, respectively. The verification of targets of miR-124 was performed using prediction softwares and luciferase reporter analysis.

Results

According to our results, the expression of Capn4 was found to be elevated, whereas the expression of miR-124 was lowered in NPC cell lines compared with normal nasopharyngeal cells. When we preformed overexpression of miR-124, it suppressed the proliferation and invasion of NPC cells. Moreover, miR-124 suppressed the expression of Capn4 by targeting Capn4 in HONE1 and CNE2 cells. When we preformed overexpression of Capn4, it reversed the inhibitory effect of miR-124 on the proliferation and invasion of NPC cells. Furthermore, miR-124–Capn4 axis decreased the levels of β-catenin, cyclin D1, and c-Myc, the components of the Wnt/β-catenin signaling pathway.

Conclusion

The suppression of proliferation and invasion of NPC cells by miR-124 were achieved by the regulation of Wnt/β-catenin signaling pathway by targeting Capn4. The results of this study revealed a novel miR-124–Capn4 regulatory axis in NPC cell lines, providing a better understanding of the pathogenesis of NPC and a promising therapeutic target for patients with NPC.

NEDD4 is involved in acquisition of epithelial-mesenchymal transition in cisplatin-resistant nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a highly invasive head-neck cancer derived from the nasopharyngeal epithelium, mainly prevalent in southern China and Southeast Asia. Radiotherapy and adjuvant cisplatin (DDP) chemotherapy are standard administrations applied in the treatment of NPC. However, resistance to chemotherapeutic drugs has recently become more common, resulting in worse treatment outcome for NPC therapy. To elucidate the underlying molecular basis of drug resistance to DDP in NPC cells, we examined the morphocytology, cell motility and molecular changes in DDP-resistant NPC cells with respect to epithelial-mesenchymal transition (EMT) features. We found that EMT is closely associated with DDP-induced drug resistance in NPC cells, as DDP-resistant cells displayed morphological and molecular markers changes consistent with EMT. Wound healing and Transwell Boyden chamber assays revealed an enhanced migration and invasion potential in DDP-resistant NPC cells. Mechanistically, upregulation of NEDD4 was observed to relate to EMT in DDP-resistant cells. More importantly, depletion of NEDD4 in resistant cells led to a partial reversion of EMT phenotypes to MET characteristics. These data suggest that NEDD4 is largely involved in EMT features and chemoresistance of NPC cancer cells. NEDD4 could be a novel therapeutic target to overcome drug resistance in successful administrations of NPC.

Exploitation of EP300 and CREBBP Lysine Acetyltransferases by Cancer

p300 and CREB-binding protein (CBP), two homologous lysine acetyltransferases in metazoans, have a myriad of cellular functions. They exert their influence mainly through their roles as transcriptional regulators but also via nontranscriptional effects inside and outside of the nucleus on processes such as DNA replication and metabolism. The versatility of p300/CBP as molecular tools has led to their exploitation by viral oncogenes for cellular transformation and by cancer cells to achieve and maintain an oncogenic phenotype. How cancer cells use p300/CBP in their favor varies depending on the cellular context and is evident by the growing list of loss- and gain-of-function genetic alterations in p300 and CBP in solid tumors and hematological malignancies. Here, we discuss the biological functions of p300/CBP and how disruption of these functions by mutations and alterations in expression or subcellular localization contributes to the cancer phenotype.

Modeling nasopharyngeal carcinoma in three dimensions

Nasopharyngeal carcinoma (NPC) is a type of cancer endemic in Asia, including Malaysia, Southern China, Hong Kong and Taiwan. Treatment resistance, particularly in recurring cases, remains a challenge. Thus, studies to develop novel therapeutic agents are important. Potential therapeutic compounds may be effectively examined using two-dimensional (2D) cell culture models, three-dimensional (3D) spheroid models or in vivo animal models. The majority of drug assessments for cancers, including for NPC, are currently performed with 2D cell culture models. This model offers economical and high-throughput screening advantages. However, 2D cell culture models cannot recapitulate the architecture and the microenvironment of a tumor. In vivo models may recapitulate certain architectural and microenvironmental conditions of a tumor, however, these are not feasible for the screening of large numbers of compounds. By contrast, 3D spheroid models may be able to recapitulate a physiological microenvironment not observed in 2D cell culture models, in addition to avoiding the impediments of in vivo animal models. Thus, the 3D spheroid model offers a more representative model for the study of NPC growth, invasion and drug response, which may be cost-effective without forgoing quality.

Regulation of Wnt/β-catenin signaling by herpesviruses

The Wnt/β-catenin signaling pathway is instrumental in successful differentiation and proliferation of mammalian cells. It is therefore not surprising that the herpesvirus family has developed mechanisms to interact with and manipulate this pathway. Successful coexistence with the host requires that herpesviruses establish a lifelong infection that includes periods of latency and reactivation or persistence. Many herpesviruses establish latency in progenitor cells and viral reactivation is linked to host-cell proliferation and differentiation status. Importantly, Wnt/β-catenin is tightly connected to stem/progenitor cell maintenance and differentiation. Numerous studies have linked Wnt/β-catenin signaling to a variety of cancers, emphasizing the importance of Wnt/β-catenin pathways in development, tissue homeostasis and disease. This review details how the alpha-, beta-, and gammaherpesviruses interact and manipulate the Wnt/β-catenin pathway to promote a virus-centric agenda.

High expression of Sox10 correlates with tumor aggressiveness and poor prognosis in human nasopharyngeal carcinoma

Purpose

The aim of the study was to detect the expression of Sox10 in human nasopharyngeal carcinoma (NPC) and investigate the relationship between its expression and the clinicopathological characteristics of NPC patients.

Patients and methods

Tumor specimens (n=105) were retrospectively collected from patients with NPC diagnosed between 2004 and 2005 who presented at Hunan Cancer Hospital. Immunohistochemistry analyses were performed to characterize the expression of Sox10 in NPC. Kaplan–Meier survival and Cox regression analyses were employed to evaluate the prognosis of 105 NPC patients.

Results

The results showed that Sox10 was markedly overexpressed in human NPC tissues. Analysis of clinicopathological parameters showed that high Sox10 expression was significantly correlated with the clinical stage (P=0.032), T classification (P=0.034), and lymph node metastasis (P=0.03). Cox regression analyses further showed that Sox10 expression was an independent prognostic factor for overall survival (P=0.005). This is the first time Sox10 has shown its importance in predicting NPC progressiveness and survival outcomes.

Conclusion

Sox10 serves as a potential biomarker for NPC patients. It may hopefully become a novel therapeutic target for NPC patients.

β-Catenin is important for cancer stem cell generation and tumorigenic activity in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is one of the most common malignant tumors with poor prognosis and recurrence in South China. The hard eradication of NPC in clinic is predominantly due to cancer stem cells (CSCs). Increasing evidence revealed that the aberrant activation of Wnt/β-catenin was positively correlated with the produce of CSCs. To further investigate the effect of β-catenin on CSCs and tumorigenesis in NPC, a CNE2 cell line (pLKO.1-sh-β-catenin-CNE2) with stably suppressed expression of β-catenin was used in this study. The expressions of biomarkers in CSCs including c-myc, Nanog, Oct3/4, Sox2, EpCAM as well as adhesion-related proteins like E-cadherin and vimentin were analyzed by western blot analysis and immunofluorescent staining. The proliferation and migration abilities were investigated by MTT assay and Transwell assay, respectively. Cell cycle was analyzed by flow cytometry. Finally, xenograft was performed to determine the effect of β-catenin on oncogenesis in vivo. Results showed that the expressions of c-myc, Nanog, Oct3/4, Sox2, and EpCAM were all decreased in pLKO.1-sh-β-catenin-CNE2 cells. It was also found that vimentin was downregulated, while E-cadherin was upregulated. Results of MTT and Transwell assays suggested that the proliferation and migration abilities were impaired by silencing of β-catenin, and more cells were arrested in G1 phase when compared with the control. In vivo study indicated that the tumor growth was markedly suppressed in experimental group. Based on current findings, β-catenin may function as an essential protein for the maintenance of migration and proliferation abilities of NPC cells, and a complicated network consisting of c-myc, Nanog, Oct3/4, Sox2, EpCAM, E-cadherin, vimentin, and β-catenin may be involved in the inherent regulation mechanisms.