Wnt/beta-catenin/tcf signaling: a critical pathway in gastrointestinal tumorigenesis

Long non-coding RNAs: crucial regulators of gastrointestinal cancer cell proliferation

Studies of long non-coding RNAs (lncRNAs) have been prevalent in the field of non-coding RNA regulation in recent years. LncRNAs exert crucial effects on malignant cell processes in the gastrointestinal system, including proliferation. Aberrant lncRNA expression, through both oncogenes and tumor suppressor genes, is instrumental to tumor cell proliferation. Here, we summarize the different molecular mechanisms and relevant signaling pathways through which multifarious lncRNAs regulate cell proliferation and we show that lncRNAs are potential biomarkers for gastrointestinal cancers.

Induction of immunoglobulin transcription factor 2 and resistance to MEK inhibitor in melanoma cells

Primary or acquired resistance to MEK inhibitors has been a barrier to successful treatment with MEK inhibitors in many tumors. In this study, we analyzed genome-wide gene expression profiling data from 6 sensitive and 6 resistant cell lines to identify candidate genes whose expression changes are associated with responses to a MEK inhibitor, selumetinib (AZD6244). Of 62 identified differentially expressed genes, we selected Immunoglobulin Transcription Factor 2, also known as transcription factor 4 as a potential drug resistance marker for further analysis. This was because the ITF-2 expression increase in resistant cell lines was relatively high and a previous study has suggested that ITF-2 functions as an oncogene in human colon cancers. We also established an AZD6244 resistant cell line (M14/AZD-3) from an AZD6244 sensitive M14 cell line. The expression of the ITF-2 was elevated both in primary AZD6244 resistant cell line, LOX-IMVI and acquired resistant cell line, M14/AZD-3. Targeted silencing of ITF-2 by siRNA significantly enhanced susceptibility to AZD6244 in resistant cells. Wnt/β-catenin pathway was activated through direct interaction of p-ERK and GSK3β. Our results suggest that up-regulation of the ITF-2 gene expression is associated with cellular resistance to MEK inhibitors, and activation of Wnt signaling pathway through interaction of p-ERK and GSK3β seems to be a mechanism for increase of ITF-2.

Comparison of dysplastic fundic gland polyps in patients with and without familial adenomatous polyposis

AIMS

Dysplastic fundic gland polyps (d-FGPs) typically arise in patients with familial adenomatous polyposis (FAP) but may occur in non-syndromic patients. They rarely become malignant, but their significance is unclear, especially in non-syndromic patients. We aimed to compare d-FGPs in patients with and without FAP, using clinicopathologic findings and β-catenin immunohistochemistry (IHC).

METHODS AND RESULTS

We identified 124 fundic gland polyps with low-grade dysplasia (LGD) or high-grade dysplasia (HGD) or indefinite for dysplasia (IFD) from 66 patients (27 with FAP; 39 non-syndromic). We recorded patient sex, age at first d-FGP, time until subsequent d-FGP (if any), history of non-gastric cancer (no patients had gastric cancer), proton-pump inhibitor use, and the presence of Helicobacter pylori. β-Catenin IHC was performed on cases with available blocks. The mean age at d-FGP diagnosis was 31 years for FAP patients and 61 years for non-syndromic patients (P < 0.0001). Sixteen FAP patients (59%) developed at least one subsequent d-FGP, as compared with 10 (27%) non-syndromic patients (P = 0.0099). The median time between d-FGP detection was 11.5 months in FAP patients and 7 months in non-syndromic patients (P = 0.82). Six FAP patients (22%) and 17 non-syndromic patients (44%) had non-gastric malignancies (P = 0.11). β-Catenin IHC showed nuclear positivity in 14 of 112 (13%) d-FGPs: 12 of 94 with LGD, two of three with HGD, and none of 15 with IFD polyps.

CONCLUSIONS

Familial adenomatous polyposis patients develop d-FGPs earlier and more often develop additional ones than non-syndromic patients. d-FGPs in FAP and non-syndromic patients have similar low rates of β-catenin nuclear IHC positivity. FAP and non-syndromic patients developed non-gastric cancers at similar rates, suggesting that d-FGPs may portend a general increased risk of carcinogenesis in non-syndromic patients.

CUL4B promotes metastasis and proliferation in pancreatic cancer cells by inducing epithelial-mesenchymal transition via the Wnt/β-catenin signaling pathway

This study determines whether cullin 4B (CUL4B) promotes pancreatic cancer (PC) metastasis by inducing epithelial-mesenchymal transition (EMT) via the Wnt/β-catenin signaling pathway. A total of 64 PC patients were enrolled in this study. Human PC cell lines were distributed into blank, negative control, shCUL4B, PLOC, PLOC-CUL4B, and PLOC-CUL4B + siRNA-β-catenin groups. The expressions of CUL4B, Wnt/β-catenin signaling pathway-related proteins, and EMT-related proteins were determined using RT-qPCR and Western blotting. The positive expressions of CUL4B and β-catenin protein in tissues were detected by immunohistochemistry. MTT assay and flow cytometry was performed for cell proliferation and cell cycle, scratch test, and transwell assay for cell migration and invasion ability. CUL4B and β-catenin were expressed at a higher level in PC tissues than in paracancerous tissues though paracancerous tissues had higher expressions of CUL4B and β-catenin than normal tissues. The PLOC-CUL4B group showed increased CUL4B, Wnt, β-catenin, LEF-1, c-Jun, Cyclin D1, N-cadherin, Vimentin, Snail, and ZEB1 expression; decreased E-cadherin expression; accelerated cell proliferation; increased S-phase cell percentages; increased cell migration ability; more liver metastases; and enlarged tumor than the PLOC and PLOC-CUL4B + siRNA-β-catenin groups. The shCUL4B group showed decreased CUL4B, Wnt, β-catenin, LEF-1, c-Jun, Cyclin D1, N-cadherin, Vimentin, Snail, and ZEB1 expression; increased E-cadherin expression; decelerated cell proliferation; decreased S-phase cell percentages; reduced cell migration ability; less liver metastases; and decreased tumor weight than the blank and negative control groups. We demonstrate that CUL4B promotes PC metastasis by inducing EMT via the Wnt/β-catenin signaling pathway. Therefore, CUL4B might be the clinical target for treating PC.

A Network Pharmacology Approach to Uncover the Multiple Mechanisms of Hedyotis diffusa Willd. on Colorectal Cancer

Background

As one of the most frequently diagnosed cancer diseases globally, colorectal cancer (CRC) remains an important cause of cancer-related death. Although the traditional Chinese herb Hedyotis diffusa Willd. (HDW) has been proven to be effective for treating CRC in clinical practice, its definite mechanisms have not been completely deciphered.

Objective

The aim of our research is to systematically explore the multiple mechanisms of HDW on CRC.

Methods

This study adopted the network pharmacology approach, which was mainly composed of active component gathering, target prediction, CRC gene collection, network analysis, and gene enrichment analysis.

Results

The network analysis showed that 10 targets might be the therapeutic targets of HDW on CRC, namely, HRAS, PIK3CA, KRAS, TP53, APC, BRAF, GSK3B, CDK2, AKT1, and RAF1. The gene enrichment analysis implied that HDW probably benefits patients with CRC by modulating pathways related to cancers, infectious diseases, endocrine system, immune system, nervous system, signal transduction, cellular community, and cell motility.

Conclusions

This study partially verified and predicted the pharmacological and molecular mechanism of HDW against CRC from a holistic perspective, which will also lay a foundation for the further experimental research and clinical rational application of HDW.

Colon cancers carrying BRAF V600E and β-catenin T41A activating mutations are resistant to numerous common anticancer drugs

Colorectal cancer is a common malignancy with a high prevalence and associated mortality rate. However, the preclinical tools currently used for drug development are insufficient. The aim of the present study was to establish and characterize a specific patient-derived colon cancer xenograft (PDCCX) mouse model for drug testing. Primary colon tumors were obtained from 10 patients by surgical resection, and tumor tissues were subsequently grafted into nude mice followed by consecutive passages. Primary tumors and xenograft tumors were collected and processed for DNA sequencing, histological evaluation and immunohistochemical staining. The responses of fifth-generation PDCCX mice to 5-fluorouracil, oxaliplatin, and cetuximab were assessed. Two PDCCX cell lines were successfully established. The histology and protein expression levels of SMAD family member 3, epidermal growth factor receptor, c-MET, caudal type homeobox 2, E-cadherin and β-catenin in the xenograft tumors were consistently maintained from the primary cancer tissues. BRAF V600E and β-catenin T41A double mutations were identified in one cell line, and were associated with a lack of response to 5-fluorouracil, oxaliplatin and cetuximab treatment. This PDCCX cell line may provide a reliable tool for preclinical evaluation of the efficacy of novel therapies that may target the BRAF V600E and β-catenin mutations.

Multi-label Deep Learning for Gene Function Annotation in Cancer Pathways

The war on cancer is progressing globally but slowly as researchers around the world continue to seek and discover more innovative and effective ways of curing this catastrophic disease. Organizing biological information, representing it, and making it accessible, or biocuration, is an important aspect of biomedical research and discovery. However, because maintaining sophisticated biocuration is highly resource dependent, it continues to lag behind the continually being generated biomedical data. Another critical aspect of cancer research, pathway analysis, has proven to be an efficient method for gaining insight into the underlying biology associated with cancer. We propose a deep-learning-based model, Stacked Denoising Autoencoder Multi-Label Learning (SdaMLL), for facilitating gene multi-function discovery and pathway completion. SdaMLL can capture intermediate representations robust to partial corruption of the input pattern and generate low-dimensional codes superior to conditional dimension reduction tools. Experimental results indicate that SdaMLL outperforms existing classical multi-label algorithms. Moreover, we found some gene functions, such as Fused in Sarcoma (FUS, which may be part of transcriptional misregulation in cancer) and p27 (which we expect will become a member viral carcinogenesis), that can be used to complete the related pathways. We provide a visual tool (https://www.keaml.cn/gpvisual) to view the new gene functions in cancer pathways.

MicroRNA-374b reduces the proliferation and invasion of colon cancer cells by regulation of LRH-1/Wnt signaling

Deregulation of microRNA (miRNA) has been suggested as a critical event in colon cancer development and progression. Recent studies have suggested that miR-374b is a novel cancer-related miRNA involved in several cancer types. Thus far, very little is known about the role of miR-374b in colon cancer; therefore, the goal of this study was to investigate the potential role of miR-374b in colon cancer. Here, we showed that miR-374b expression was significantly downregulated in colon cancer tissues and cell lines. Overexpression of miR-374b inhibited the proliferation and invasion of colon cancer cells, while miR-374b suppression promoted colon cancer cell proliferation and invasion. Liver receptor homolog-1 (LRH-1) was identified as a target of miR-374b in colon cancer cells. Both the mRNA and protein expression of LRH-1 were regulated by miR-374b. In addition, an inverse correlation between LRH-1 mRNA and miR-374b expression was evidenced in colon cancer specimens. Notably, overexpression of miR-374b also downregulated the Wnt signaling in colon cancer cells. Furthermore, restoration of LRH-1 expression significantly abolished the antitumor effect of miR-374b in colon cancer cells. These findings suggest that miR-374b inhibits colon cancer cell proliferation and invasion through downregulation of LRH-1 expression. Inhibiting LRH-1 by miR-374b may represent a novel therapeutic strategy for the treatment of colon cancer.

A Small Molecule Inhibitor of the β-Catenin-TCF4 Interaction Suppresses Colorectal Cancer Growth In Vitro and In Vivo

Colorectal cancer is associated with aberrant activation of the Wnt pathway. β-Catenin plays essential roles in the Wnt pathway by interacting with T-cell factor 4 (TCF4) to transcribe oncogenes. We synthesized a small molecule, referred to as HI-B1, and evaluated signaling changes and biological consequences induced by the compound. HI-B1 inhibited β-catenin/TCF4 luciferase activity and preferentially caused apoptosis of cancer cells in which the survival is dependent on β-catenin. The formation of the β-catenin/TCF4 complex was disrupted by HI-B1 due to the direct interaction of HI-B1 with β-catenin. Colon cancer patient-derived xenograft (PDX) studies showed that a tumor with higher levels of β-catenin expression was more sensitive to HI-B1 treatment, compared to a tumor with lower expression levels of β-catenin. The different sensitivities of PDX tumors to HI-B1 were dependent on the β-catenin expression level and potentially could be further exploited for biomarker development and therapeutic applications against colon cancer.

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HI-B1 is a synthesized compound identified as a β-catenin inhibitor suppressing the β-catenin-TCF4 protein interaction.

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HI-B1 preferentially causes apoptosis in β-catenin-dependent cancer cells.

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A colon cancer PDX mouse model with a high level of β-catenin is sensitive to HI-B1.

β-catenin is an important protein that facilitates colon cancer. Shin et al. synthesized and identified HI-B1 as a direct β-catenin inhibitor. HI-B1 disrupted formation of the β-catenin-TCF4 protein complex. HI-B1 preferentially caused apoptosis of cancer cells in which the survival is dependent on β-catenin. In a comparison of two colon cancer PDX models with different β-catenin levels, they showed that β-catenin-high PDX is more sensitive to HI-B1 treatment than β-catenin-low PDX. HI-B1 could thus be further developed as a colon cancer drug, and β-catenin expression levels might be a predictive biomarker for colon cancer therapy using β-catenin inhibitors.

Solasodine inhibits human colorectal cancer cells through suppression of the AKT/glycogen synthase kinase-3β/β-catenin pathway

Solasodine is a main active component isolated from Solanum incanum L. that performs a wide range of functions containing anti‐oxidant, anti‐infection, and neurogenesis promotion. In this study, we explored the influence of solasodine on three types of human colorectal cancer (CRC) cell lines. The results show that solasodine prohibited CRC cell proliferation dose‐ and time‐dependently and impeded CRC cell motility by downregulating MMPs. Solasodine was also found to fuel caspase‐cascade reaction and increase the ratio between Bax and Bcl‐2 so as to induce CRC cell apoptosis. When cells were pretreated with AKT activator (insulin‐like growth factor‐1) followed by solasodine, the solasodine‐induced apoptosis was partially abrogated by insulin‐like growth factor‐1. Moreover, solasodine hindered tumor development and stimulated similar mechanisms in vivo. In general, our study provides the first evidence that solasodine has a suppressive effect on CRC cells and that this agent may be a novel therapeutic drug for CRC treatment.

γ-Catenin acts as a tumor suppressor through context-dependent mechanisms in colorectal cancer

PURPOSE

γ-Catenin is a protein closely related to β-catenin. While the overexpression of β-catenin has been linked with impaired prognosis and survival in various malignancies, both oncogenic and tumor suppressor functions have been described for γ-catenin. Thus, its role in cancer remains controversial. In this study, we examined the impact of γ-catenin expression on the malignant potential of colorectal cancer cells.

METHODS

γ-Catenin was knocked down by short interfering RNA in the γ-catenin-proficient DLD-1 cell line and stably overexpressed in the γ-catenin-deficient cell line RKO. The effects of these molecular manipulations on the malignant potential of the cell lines were tested in vitro and in vivo in a xenograft tumor model.

RESULTS

γ-Catenin contributed to Wnt signaling independent of the cellular context. Unlike its sister molecule β-catenin, γ-catenin inhibited cellular invasion and anoikis in cells endogenously expressing γ-catenin. In line with this tumor suppressor function, its de novo expression in RKO cells inhibited proliferation via cell cycle arrest. In a xenograft tumor model, overexpression of γ-catenin starkly reduced tumor growth in vivo.

CONCLUSIONS

This is the first report demonstrating a tumor-suppressive effect of γ-catenin in colorectal cancer both in vitro and in vivo. Detailed in vitro analysis revealed that effects of γ-catenin differ in γ-catenin proficient and deficient cells, indicating that its function in colorectal cancer is dependent on the cellular context. This finding adds to our understanding of γ-catenin and may have implications for future studies of catenin/Wnt targeted cancer therapies.

Effect of carcinogen 1,2-dimethylhydrazine treatment on fiber types in skeletal muscles of male Wistar rats

The cancerogen 1,2-dimethylhydrazine (DMH), widely used in the experimental animal model of carcinogenesis, affects various organs, but its effect on muscle fibers is unknown. To evaluate the effect of 15-week DMH treatment on the fiber size and myosin heavy chain (MyHC) isoforms, which substantially determine fiber types and their contractile characteristics, pure and hybrid fiber types were immunohistochemically determined according to the MyHC isoform expression in soleus, extensor digitorum longus, gastrocnemius medialis and lateralis muscles of DMH-treated and control male Wistar rats. Whereas the size of fibers was mostly unaffected, the MyHC isoform expression was partially affected in both gastrocnemius samples, but not in the soleus and extensor digitorum longus of DMH-treated rats. The lower proportions of hybrid fiber types and especially that of type 1/2x in most gastrocnemius samples of DMH-treated rats resulted in a shift towards a single MyHC isoform expression, but the extent and pattern of the MyHC isoform shift varied across the different gastrocnemius samples. Such variable response to DMH treatment across muscles indicates that each muscle possesses its own adaptive range. These findings are essential for an accurate evaluation of skeletal muscle characteristics in DMH animal model.

MicroRNA-136 inhibits colon cancer cell proliferation and invasion through targeting liver receptor homolog-1/Wnt signaling

An increasing number of studies have reported that microRNAs (miRNAs) are involved in the malignant behavior of colon cancer cells through directly targeting multiple tumor suppressors or oncogenes. The expression and role of miR-136 has been reported in several types of human cancer. However, the role of miR-136 in colon cancer remains unclear. In this study, we aimed to investigate the expression and function of miR-136 in colon cancer and the potential underlying mechanism. Here, we found that miR-136 was decreased in colon cancer cell lines and tissues. Overexpression of miR-136 inhibited the proliferation and invasion in SW480 and HCT116 cell lines while suppression of miR-136 exhibited the opposite effect. Liver receptor homolog-1 (LRH-1) was identified as a direct target gene of miR-136. Notably, miR-136 overexpression suppressed LRH-1 expression as well as Wnt signaling in SW480 and HCT116 cell lines. The miR-136 expression level inversely correlated with LRH-1 mRNA expression in colon cancer specimens. Moreover, overexpression of LRH-1 partially reversed the miR-136-induced antitumor effect in SW480 and HCT116 cell lines. Taken together, these findings suggest that miR-136 functions as a negative regulator in colon cancer progression by targeting LRH-1 and that miR-136 downregulation contributes to high expression of LRH-1 and aberrant activation of Wnt signaling, leaving open the possibility that miR-136 may serve as a potential therapeutic target for colon cancer.

p53-inducible long non-coding RNA PICART1 mediates cancer cell proliferation and migration

Long non-coding RNAs (lncRNAs) function in the development and progression of cancer, but only a small portion of lncRNAs have been characterized to date. A novel lncRNA transcript, 2.53 kb in length, was identified by transcriptome sequencing analysis, and was named p53-inducible cancer-associated RNA transcript 1 (PICART1). PICART1 was found to be upregulated by p53 through a p53-binding site at -1808 to -1783 bp. In breast and colorectal cancer cells and tissues, PICART1 expression was found to be decreased. Ectopic expression of PICART1 suppressed the growth, proliferation, migration, and invasion of MCF7, MDA-MB-231 and HCT116 cells whereas silencing of PICART1 stimulated cell growth and migration. In these cells, the expression of PICART1 suppressed levels of p-AKT (Thr308 and Ser473) and p-GSK3β (Ser9), and accordingly, β-catenin, cyclin D1 and c-Myc expression were decreased, while p21Waf/cip1 expression was increased. Together these data suggest that PICART1 is a novel p53-inducible tumor-suppressor lncRNA, functioning through the AKT/GSK3β/β-catenin signaling cascade.

Characterization of new-generation aminoglycoside promoting premature termination codon readthrough in cancer cells

Nonsense mutations, generating premature termination codons (PTCs), account for 10% to 30% of the mutations in tumor suppressor genes. Nonsense translational suppression, induced by small molecules including gentamicin and G418, has been suggested as a potential therapy to counteract the deleterious effects of nonsense mutations in several genetic diseases and cancers. We describe here that NB124, a synthetic aminoglycoside derivative recently developed especially for PTC suppression, strongly induces apoptosis in human tumor cells by promoting high level of PTC readthrough. Using a reporter system, we showed that NB124 suppressed several of the PTCs encountered in tumor suppressor genes, such as the p53 and APC genes. We also showed that NB124 counteracted p53 mRNA degradation by nonsense-mediated decay (NMD). Both PTC suppression and mRNA stabilization contributed to the production of a full-length p53 protein capable of activating p53-dependent genes, thereby specifically promoting high levels of apoptosis. This new-generation aminoglycoside thus outperforms the only clinically available readthrough inducer (gentamicin). These results have important implications for the development of personalised treatments of PTC-dependent diseases and for the development of new drugs modifying translation fidelity.

β-catenin nuclear translocation in colorectal cancer cells is suppressed by PDE10A inhibition, cGMP elevation, and activation of PKG

Phosphodiesterase 10A (PDE10) is a cGMP and cAMP degrading PDE isozyme that is highly expressed in the brain striatum where it appears to play an important role in cognition and psychomotor activity. PDE10 inhibitors are being developed for the treatment of schizophrenia and Huntington's disease and are generally well tolerated, possibly because of low expression levels in most peripheral tissues. We recently reported high levels of PDE10 in colon tumors and that genetic silencing of PDE10 by siRNA or inhibition with small molecule inhibitors can suppress colon tumor cell growth with a high degree of selectivity over normal colonocytes (Li et al., Oncogene 2015). These observations suggest PDE10 may have an unrecognized role in tumorigenesis. Here we report that the concentration range by which the highly specific PDE10 inhibitor, Pf-2545920 (MP-10), inhibits colon tumor cell growth parallels the concentration range required to increase cGMP and cAMP levels, and activates PKG and PKA, respectively. Moreover, PDE10 knockdown by shRNA reduces the sensitivity of colon tumor cells to the growth inhibitory activity of Pf-2545920. Pf-2545920 also inhibits the translocation of β-catenin to the nucleus, thereby reducing β-catenin mediated transcription of survivin, resulting in caspase activation and apoptosis. PDE10 mRNA was also found to be elevated in colon tumors compared with normal tissues. These findings suggest that PDE10 can be targeted for cancer therapy or prevention whereby inhibition results in cGMP elevation and PKG activation to reduce β-catenin-mediated transcription of survival proteins leading to the selective apoptosis of cancer cells.

Potential role of Wnt/β-catenin signaling in blastic transformation of chronic myeloid leukemia: cross talk between β-catenin and BCR-ABL

Chronic myeloid leukemia (CML) results from malignant transformation of hematopoietic stem cells induced by the BCR-ABL oncogene. Transformation from chronic to blastic phase is the lethal step in CML. Leukemic stem cells (LSCs) are the basic reason for blastic transformation. It has been shown that Wnt/β-catenin signaling contributes to the self-renewal capacity and proliferation of LSCs in CML. However, the role of Wnt/β-catenin signaling in blastic transformation of CML is still obscure. Here, we explored the relationship between BCR-ABL and β-catenin signaling in vitro and in vivo. We found that BCR-ABL stimulated β-catenin via activation of PI3K/AKT signaling in blastic phase CML cells. Inhibition of the kinase activity of BCR-ABL, PI3K, or AKT decreased the level of β-catenin in both K562 cells and a CML mouse model and suppressed the transcription of downstream target genes (c-myc and cyclin D1). In addition, inhibition of the BCR-ABL/PI3K/AKT pathway delayed the disease progression in the CML mouse model. To further explore the role of β-catenin in the self-renewal and survival of CML LSCs, we established a secondary transplantation CML mouse model. Our data revealed that inhibition of the BCR-ABL/PI3K/AKT pathway reduced the tumor-initiating ability of K562 cells, decreased leukemia cell infiltration into peripheral blood and bone marrow, and prolonged the survival of mice. In conclusion, our data indicate a close relationship between β-catenin and BCR-ABL/PI3K/AKT in blastic phase CML. β-Catenin inhibition may be of therapeutic value by targeting LSCs in combination with a tyrosine kinase inhibitor, which may delay blastic transformation of CML.

Modulation of Inflammatory Responses by Wnt/β-Catenin Signaling in Dendritic Cells: A Novel Immunotherapy Target for Autoimmunity and Cancer

The Wnt/β-catenin pathway is an evolutionarily conserved signaling pathway critical for several biological processes. An aberrant Wnt/β-catenin signaling is linked to several human diseases. Emerging studies have highlighted the regulatory role of the Wnt/β-catenin signaling pathway in normal physiological processes of parenchymal and hematopoietic cells. Recent studies have shown that the activation of Wnt/β-catenin pathway in dendritic cells (DCs) play a critical role in mucosal tolerance and suppression of chronic autoimmune pathologies. Alternatively, tumors activate Wnt/β-catenin pathway in DCs to induce immune tolerance and thereby evade antitumor immunity through suppression of effector T cell responses and promotion of regulatory T cell responses. Here, we review our work and current understanding of how Wnt/β-catenin signaling in DCs shapes the immune response in cancer and autoimmunity and discuss how Wnt/β-catenin pathway can be targeted for successful therapeutic interventions in various human diseases.

MicroRNA-219-5p Represses the Proliferation, Migration, and Invasion of Gastric Cancer Cells by Targeting the LRH-1/Wnt/β-Catenin Signaling Pathway

MicroRNAs (miRNAs) are reportedly involved in gastric cancer development and progression. In particular, miR-219-5p has been reported to be a tumor-associated miRNA in human cancer. However, the role of miR-219-5p in gastric cancer remains unclear. In this study, we investigated for the first time the potential role and underlying mechanism of miR-219-5p in the proliferation, migration, and invasion of human gastric cancer cells. miR-219-5p was found to be markedly decreased in gastric cancer tissues and cell lines compared with adjacent tissues and normal gastric epithelial cells. miR-219-5p mimics or anti-miR-219-5p was transfected into gastric cancer cell lines to overexpress or suppress miR-219-5p expression, respectively. Results showed that miR-219-5p overexpression significantly decreased the proliferation, migration, and invasion of gastric cancer cells. Conversely, miR-219-5p suppression demonstrated a completely opposite effect. Bioinformatics and luciferase reporter assays indicated that miR-219-5p targeted the 3′-untranslated region of the liver receptor homolog-1 (LRH-1), a well-characterized oncogene. Furthermore, miR-219-5p inhibited the mRNA and protein levels of LRH-1. LRH-1 mRNA expression was inversely correlated with miR-219-5p expression in gastric cancer tissues. miR-219-5p overexpression significantly decreased the Wnt/β-catenin signaling pathway in gastric cancer cells. Additionally, LRH-1 restoration can markedly reverse miR-219-5p-mediated tumor suppressive effects. Our study suggests that miR-219-5p regulated the proliferation, migration, and invasion of human gastric cancer cells by suppressing LRH-1. miR-219-5p may be a potential target for gastric cancer therapy.

5-hydroxytryptamine receptor (5-HT1DR) promotes colorectal cancer metastasis by regulating Axin1/β-catenin/MMP-7 signaling pathway

Overexpression of 5-hydroxytryptamine (5-HT) in human cancer contributes to tumor metastasis, but the role of 5-HT receptor family in cancer has not been thoroughly explored. Here, we report overexpression of 5-HT_1D receptor (5-HT_1DR) was associated with Wnt signaling pathway and advanced tumor stage. The underlying mechanism of 5-HT_1DR-promoted tumor invasion was through its activation on the Axin1/β-catenin/MMP-7 pathway. In an orthotopic colorectal cancer mouse model, we demonstrated that a 5-HT_1DR antagonist (GR127935) effectively inhibited tumor metastasis through targeting Axin1. Furthermore, in intestinal epithelium cells, we observed that 5-HT_1DR played an important role in cell invasion via Axin1/β-catenin/MMP-7 pathway. Together, our findings reveal an essential role of the physiologic level of 5-HT_1DR in pulmonary metastasis of colorectal cancer.

Colorectal Carcinogenesis, Radiation Quality, and the Ubiquitin-Proteasome Pathway

Adult colorectal epithelium undergoes continuous renewal and maintains homeostatic balance through regulated cellular proliferation, differentiation, and migration. The canonical Wnt signaling pathway involving the transcriptional co-activator β-catenin is important for colorectal development and normal epithelial maintenance, and deregulated Wnt/β-catenin signaling has been implicated in colorectal carcinogenesis. Colorectal carcinogenesis has been linked to radiation exposure, and radiation has been demonstrated to alter Wnt/β-catenin signaling, as well as the proteasomal pathway involved in the degradation of the signaling components and thus regulation of β-catenin. The current review discusses recent progresses in our understanding of colorectal carcinogenesis in relation to different types of radiation and roles that radiation quality plays in deregulating β-catenin and ubiquitin-proteasome pathway (UPP) for colorectal cancer initiation and progression.

Upregulated expression of DIXDC1 in intestinal-type gastric carcinoma: co-localization with β-catenin and correlation with poor prognosis

Background

DIXDC1 (Dishevelled-Axin domain containing 1) is a positive regulator of the Wnt pathway. In the field of cancer research, the role of DIXDC1 is unclear. Our previous in vitro study showed that DIXDC1 enhances β-catenin nuclear accumulation in gastric cancer cell lines. The aim of this study was to detect the expression of DIXDC1 in different histological subtypes of gastric carcinoma and to evaluate the correlation between the expression of DIXDC1 and β-catenin localization and clinicopathological parameters, including patients’ survival.

Methods

Immunohistochemical staining was performed to characterize the expression of DIXDC1 and β-catenin in archived materials from 259 cases of gastric carcinoma. The χ2 test and the Fisher’s test were used to analyze correlations between DIXDC1 expression, β-catenin localization, and clinicopathological parameters. Univariate analyses were performed using the Kaplan–Meier method, and the survival difference between groups was assessed by the log-rank test. Multivariate analysis was performed using the Cox proportional hazards regression model.

Results

Positive DIXDC1 staining was detected in tumor cells in 123 of 259 (47.5 %) cases. DIXDC1 expression in gastric carcinoma was significantly correlated with the histological intestinal-type (P < 0.001), the depth of tumor invasion (P < 0.001) and the lymph node metastasis (P = 0.006). In the intestinal-type, DIXDC1 was correlated with the nuclear and cytoplasmic β-catenin expression (P = 0.002). Kaplan–Meier analysis indicated that patients with high DIXDC1 expression had poor disease-specific survival (P < 0.001), especially in the intestinal-type. Moreover, multivariate regression analysis showed that positive expression of DIXDC1 was an independent prognostic predictor of intestinal-type gastric carcinoma.

Conclusion

Our study indicated that DIXDC1 is a significant independent prognostic indicator in intestinal-type gastric carcinoma that plays an important role in carcinogenesis and progression of gastric carcinoma through the Wnt signaling pathway.

The Anti-Tumor Activity of Succinyl Macrolactin A Is Mediated through the β-Catenin Destruction Complex via the Suppression of Tankyrase and PI3K/Akt

Accumulated gene mutations in cancer suggest that multi-targeted suppression of affected signaling networks is a promising strategy for cancer treatment. In the present study, we report that 7-O-succinyl macrolactin A (SMA) suppresses tumor growth by stabilizing the β-catenin destruction complex, which was achieved through inhibition of regulatory components associated with the complex. SMA significantly reduced the activities of PI3K/Akt, which corresponded with a decrease in GSK3β phosphorylation, an increase in β-catenin phosphorylation, and a reduction in nuclear β-catenin content in HT29 human colon cancer cells. At the same time, the activity of tankyrase, which inhibits the β-catenin destruction complex by destabilizing the axin level, was suppressed by SMA. Despite the low potency of SMA against tankyrase activity (IC₅₀ of 50.1 μM and 15.5 μM for tankyrase 1 and 2, respectively) compared to XAV939 (IC₅₀ of 11 nM for tankyrase 1), a selective and potent tankyrase inhibitor, SMA had strong inhibitory effects on β-catenin-dependent TCF/LEF1 transcriptional activity (IC₅₀ of 39.8 nM), which were similar to that of XAV939 (IC₅₀ of 28.1 nM). In addition to suppressing the colony forming ability of colon cancer cells in vitro, SMA significantly inhibited tumor growth in CT26 syngenic and HT29 xenograft mouse tumor models. Furthermore, treating mice with SMA in combination with 5-FU in a colon cancer xenograft model or with cisplatin in an A549 lung cancer xenograft model resulted in greater anti-tumor activity than did treatment with the drugs alone. In the xenograft tumor tissues, SMA dose-dependently inhibited nuclear β-catenin along with reductions in GSK3β phosphorylation and increases in axin levels. These results suggest that SMA is a possible candidate as an effective anti-cancer agent alone or in combination with cytotoxic chemotherapeutic drugs, such as 5-FU and cisplatin, and that the mode of action for SMA involves stabilization of the β-catenin destruction complex through inhibition of tankyrase and the PI3K/Akt signaling pathway.

Frequent activation of the β-catenin gene in sporadic colorectal carcinomas: A mutational & expression analysis

β-catenin (CTNNB1), an oncogene/onco-protein and an adhesion molecule is a key effector in colorectal cancer (CRC). Its activation, and subsequent up-regulation of Wnt-signaling, is an important event in the development of certain human cancers including CRC. Mutations in the β-catenin gene in the region of serine-threonine glycogen kinase (GSK)-3β phosphorylation target sites have been identified in colorectal cancer in humans. In the current study, we investigated 60 sporadic colorectal adenocarcinomas along with adjoining and normal mucosa cases in humans for β-catenin mutations. Thirteen of sixty colorectal tumors from humans had point mutations with a frequency of 21.66% at codons 24, 26, 27, 32, 34, 35, 41, 42,43, 46, 49, 54, 55, or 67 sites which are mutated in colorectal cancer and some of these sites in other cancers. Thus, there appears to be a key involvement of β-catenin activation in human colorectal carcinogenesis. mRNA expression analysis using q-Real Time PCR showed 21.5-fold up-regulation of β-catenin mRNA in tumor tissue compared to normal and adjoining mucosa. Protein expression analysis using immunohistochemistry, confocal microscopy, and Western blot confirmed aberrant accumulation of β-catenin protein along the nucleus and cytoplasm following mutation. The observed mutations and up-regulation of mRNA in tumors, and the increased expression of β-catenin protein in CRC suggest that these alterations are early and prognostic events in sporadic colorectal carcinogenesis in humans. © 2015 Wiley Periodicals, Inc.

Exome sequencing of a colorectal cancer family reveals shared mutation pattern and predisposition circuitry along tumor pathways

The molecular basis of cancer and cancer multiple phenotypes are not yet fully understood. Next Generation Sequencing promises new insight into the role of genetic interactions in shaping the complexity of cancer. Aiming to outline the differences in mutation patterns between familial colorectal cancer cases and controls we analyzed whole exomes of cancer tissues and control samples from an extended colorectal cancer pedigree, providing one of the first data sets of exome sequencing of cancer in an African population against a background of large effective size typically with excess of variants. Tumors showed hMSH2 loss of function SNV consistent with Lynch syndrome. Sets of genes harboring insertions-deletions in tumor tissues revealed, however, significant GO enrichment, a feature that was not seen in control samples, suggesting that ordered insertions-deletions are central to tumorigenesis in this type of cancer. Network analysis identified multiple hub genes of centrality. ELAVL1/HuR showed remarkable centrality, interacting specially with genes harboring non-synonymous SNVs thus reinforcing the proposition of targeted mutagenesis in cancer pathways. A likely explanation to such mutation pattern is DNA/RNA editing, suggested here by nucleotide transition-to-transversion ratio that significantly departed from expected values (p-value 5e-6). NFKB1 also showed significant centrality along with ELAVL1, raising the suspicion of viral etiology given the known interaction between oncogenic viruses and these proteins.

Emetine inhibits migration and invasion of human non-small-cell lung cancer cells via regulation of ERK and p38 signaling pathways

Emetine is a natural compound originated from ipecac roots. It was commonly used as anti-protozoal and vomiting agent. The apoptosis-inducing effect of emetine makes it considered as a potential anti-cancer agent for various human cancers. Here in this study, we report that emetine inhibits migration and invasion of human non-small-cell lung cancer (NSCLC) cells. Modulation of three major mitogen-activated protein kinases (MAPKs), ERK, p38 and JNK, is well known to be involved in regulation of matrix metalloproteinases (MMPs), which are essential in tissue remodeling and extracellular matrix (ECM) degradation, for cancer cells to spread out from the origin of tumorigenesis. Emetine regulates two major MAPKs, p38 and ERK. Differential inhibition/stimulation of ERK and p38 induced differential suppressions of β-catenin and c-myc transcription factors. This leads to the selective down-regulation of MMP-2 and MMP-9, two major gelatinases which can degrade ECM components, and RECK, a negative regulator of MMP-9.

ARMc8 indicates aggressive colon cancers and promotes invasiveness and migration of colon cancer cells

Recent studies have implicated ARMc8 in promoting tumor formation in non-small cell lung cancer and breast cancer; however, so far, no studies have revealed the expression pattern or cellular function of ARMc8 in colon cancer. In this study, we used immunohistochemical staining to measure ARMc8 expression in 206 cases of colon cancer and matched adjacent normal colon tissue. Clinically important behaviors of cells, including invasiveness and migration, were evaluated after upregulation of ARMc8 expression in HT29 cells through gene transfection or downregulation of expression in LoVo cells using RNAi. We found that ARMc8 was primarily located in the membrane and cytoplasm of tumor cells, and its expression level was significantly higher in colon cancer in comparison to that in the adjacent normal colon tissues (p < 0.001). ARMc8 expression was closely related to TNM stage (p = 0.006), lymph node metastasis (p = 0.001), and poor prognosis (p = 0.002) of colon cancer. The invasiveness and migration capacity of HT29 cells transfected with ARMc8 were significantly greater than those of control cells (p < 0.001), while ARMc8 siRNA treatment significantly reduced cell invasion and migration in LoVo cells (p < 0.001). Furthermore, we demonstrated that ARMc8 could upregulate the expression of MMP7 and snail and downregulate the expression of p120ctn and α-catenin. Therefore, ARMc8 probably enhanced invasiveness and metastatic capacity by affecting these tumor-associated factors, thereby playing a role in enhancing the tumorigenicity of colon cancer cells. ARMc8 is likely to become a potential therapeutic target for colon cancer.

A novel biomarker ARMc8 promotes the malignant progression of ovarian cancer

Ovarian cancer is the most lethal gynecologic malignancy worldwide, and the survival rates have remained low in spite of medical advancements. More research is dedicated to the identification of novel biomarkers for this deadly disease. The association between ARMc8 and ovarian cancer remained unraveled. In this study, immunohistochemical staining was used to examine ARMc8 expression in 247 cases of ovarian cancer, 19 cases of borderline ovarian tumors, 41 cases of benign ovarian tumors, and 9 cases of normal ovarian tissues. It was shown that ARMc8 was predominantly located in the cytoplasm of tumor cells, and its expression was up-regulated in the ovarian cancer (61.9%) and the borderline ovarian tumor tissues (57.9%), in comparison with the benign ovarian tumors (12.2%; P < .05) and the normal ovarian tissues (11.1%; P < .05). In ovarian cancer, ARMc8 expression was closely related to International Federation of Gynecology and Obstetrics stages (P = .002), histology grade (P < .001), lymph node metastasis (P = .008), and poor prognosis (P < .001). Univariate and multivariate Cox analyses revealed that ARMc8 expression was an independent prognostic factor for ovarian cancer (P = .039 and P = .005). In addition, ARMc8 could promote the invasion and migration of ovarian cancer cells. Overexpressing ARMc8 enhanced the invasion and metastasis capacity of ARMc8-low Cavo-3 cells (P < .001), whereas interfering ARMc8 significantly reduced cell invasion and metastasis in ARMc8-high SK-OV-3 cells (P < .001). Furthermore, ARMc8 could up-regulate matrix metalloproteinase-7 and snail and down-regulate α-catenin, p120ctn, and E-cadherin. Collectively, ARMc8 may enhance the invasion and metastasis of ovarian cancer cells and likely to become a potential therapeutic target for ovarian cancer.

An integrated approach of predicted miR-34a targets identifies a signature for gastric cancer

microRNA-34a (miRNA/miR-34a) functions as a tumor suppressor gene in gastric cancer and may be involved in system-wide regulatory networks. To clarify the expression of all predicted target genes of this miRNA, a comprehensive and systematic analysis of miR-34a-target genes in gastric cancer was conducted in the present study. In the initial analysis, the potential functions, pathways and networks of gastric cancer-associated molecules and miR-34a targets were identified. In the final integrative analysis of gastric cancer-associated miR-34a targets, 30 hub genes were identified using overlap calculations, indicating that miR-34a may be significant in the development and progression of gastric cancer through the Smad signaling pathway, the cell cycle, the mitogen-activated protein kinase signaling pathway, apoptosis, the Notch signaling pathway and other pathways. The present study provides a bioinformatic analysis of miR-34a-targets in gastric cancer, describes numerous target genes and novel coregulatory networks, and may provide an opportunity to identify a critical regulatory network for predicting the molecular mechanisms of miR-34a in the development and progression of gastric cancer.

Role of MCP-1 in alcohol-induced aggressiveness of colorectal cancer cells

Epidemiological studies demonstrate that alcohol consumption is associated with an increased risk of colorectal cancer (CRC). In addition to promoting carcinogenesis, alcohol may also accelerate the progression of existing CRC. We hypothesized that alcohol may enhance the aggressiveness of CRC. In this study, we investigated the effect of alcohol on the migration/invasion and metastasis of CRC. Alcohol increased the migration/invasion of colorectal cancer cells (DLD1, HCT116, HT29, and SW480) in a concentration-dependent manner. Among these colon cancer cell lines, HCT116 cells were most responsive while HT29 cells were the least responsive to ethanol-stimulated cell migration/invasion. These in vitro results were supported by animal studies which demonstrated that ethanol enhanced the metastasis of colorectal cancer cells to the liver and lung. Monocyte chemoattractant protein-1 (MCP-1) is a chemokine that plays an important role in regulating tumor microenvironment and metastasis. Alcohol increased the expression of MCP-1 and its receptor CCR2 at both protein and mRNA levels. The pattern of alcohol-induced alterations in MCP-1 expression was consistent with its effect on migration/invasion; HCT116 cells displayed the highest up-regulation of MCP-1/CCR2 in response to alcohol exposure. An antagonist of CCR2 blocked alcohol-stimulated migration. Alcohol caused an initial cytosolic accumulation of β-catenin and its subsequent nuclear translocation by inhibiting GSK3β activity. Alcohol stimulated the activity of MCP-1 gene promoter in a β-catenin-dependent manner. Furthermore, knock-down of MCP-1/CCR2 or β-catenin was sufficient to inhibit alcohol-induced cell migration/invasion. Together, these results suggested that alcohol may promote the metastasis of CRC through modulating GSK3β/β-catenin/MCP-1 pathway.

Hypoxia-inducible factor-1α and Wnt/β-catenin signaling pathways promote the invasion of hypoxic gastric cancer cells

The present study aimed to examine the association between hypoxia-inducible factor (HIF)-1α and the Wnt/β-catenin signaling pathway in a hypoxic environment. The study also aimed to explore the possible mechanisms underlying the invasion of hypoxic gastric cancer cells in vitro and in vivo. The pcDNA™ 6.2‑GW/EmGFP‑miR‑β‑catenin plasmid was transfected into SGC‑7901 gastric cancer cells, resulting in cells with stable suppression of β‑catenin expression. The biological characteristics of the control, liposome, negative control, β‑catenin knockdown, hypoxia and hypoxia β‑catenin knockdown groups were tested using an invasion assay. The differences in the invasive capacity of the control, negative control and liposome groups were not statistically significant. However, the hypoxia group demonstrated a significantly enhanced invasive capacity, as compared with that in the control group (P<0.05). In the hypoxia β‑catenin knockdown group, reduced cell penetration and diminished invasive behavior was observed (P<0.05). In the hypoxia and double (chemical + physical) hypoxia groups, HIF‑1α, β‑catenin, urokinase‑type plasminogen activator (uPA) and matrix metalloproteinase (MMP‑7) protein and mRNA expression levels were elevated. In response to knockdown of β‑catenin expression, HIF‑1α, β‑catenin, uPA and MMP‑7 protein as well as mRNA expression levels were significantly reduced in the hypoxia β‑catenin knockdown and the double hypoxia β‑catenin knockdown groups. In an in vivo experiment, the growth rate of xenograft tumors of hypoxic and control cells was high alongside increased HIF‑1α, β‑catenin, uPA and MMP‑7 levels according to western blot and immunohistochemical analyses, while growth and protein levels of tumors from hypoxic β‑catenin knockdown cells were significantly lower and those of β‑catenin knockdown cells were lowest. In conclusion, these results suggested that HIF‑1α activation was able to regulate the Wnt/β‑catenin pathway, and that HIF‑1α may be controlled by the Wnt/β‑catenin pathway. A potential mechanism underlying SGC‑7901 tumorigenicity is the activation of the Wnt/β‑catenin signaling pathway, which activates uPA and MMP‑7 expression and contributes to the enhanced invasion of hypoxic cancer cells.

Liver receptor homolog-1 (LRH-1): a potential therapeutic target for cancer

Liver receptor homolog-1 (LRH-1) is a nuclear receptor involved in various biological processes. This nuclear receptor has critical functions in embryonic development as well as in adult homeostasis. Although the physiological functions of LRH-1 in normal breast, pancreas, and intestine have been widely investigated, the dysregulation that occurs during pathological conditions is not well understood. LRH-1 has been implicated in pancreatic, breast, and gastrointestinal cancer, where it exerts its effect of initiation and progression by promoting cell proliferation and metastasis. In addition to mechanistic studies, LRH-1 agonists and antagonists are being explored. Identification and development of endogenous and synthetic ligands has been pursued using computational-based structural analysis. Through ligand identification and a thorough understanding of the pathological roles of LRH-1, new therapeutic avenues for cancer treatment based upon LRH-1 may be a desirable focus for further research.

Molecular signalling in hepatocellular carcinoma: Role of and crosstalk among WNT/ß-catenin, Sonic Hedgehog, Notch and Dickkopf-1

Hepatocellular carcinoma is the sixth most common cancer worldwide. In the majority of cases, there is evidence of existing chronic liver disease from a variety of causes including viral hepatitis B and C, alcoholic liver disease and nonalcoholic steatohepatitis. Identification of the signalling pathways used by hepatocellular carcinoma cells to proliferate, invade or metastasize is of paramount importance in the discovery and implementation of successfully targeted therapies. Activation of Wnt/β-catenin, Notch and Hedgehog pathways play a critical role in regulating liver cell proliferation during development and in controlling crucial functions of the adult liver in the initiation and progression of human cancers. β-catenin was identified as a protein interacting with the cell adhesion molecule E-cadherin at the cell-cell junction, and has been shown to be one of the most important mediators of the Wnt signalling pathway in tumourigenesis. Investigations into the role of Dikkopf-1 in hepatocellular carcinoma have demonstrated controversial results, with a decreased expression of Dickkopf-1 and soluble frizzled-related protein in various cancers on one hand, and as a possible negative prognostic indicator of hepatocellular carcinoma on the other. In the present review, the authors focus on the Wnt⁄β-catenin, Notch and Sonic Hedgehog pathways, and their interaction with Dikkopf-1 in hepatocellular carcinoma.

Scopadulciol, Isolated from Scoparia dulcis, Induces β-Catenin Degradation and Overcomes Tumor Necrosis Factor-Related Apoptosis Ligand Resistance in AGS Human Gastric Adenocarcinoma Cells

Scopadulciol (1), a scopadulan-type diterpenoid, was isolated from Scoparia dulcis along with three other compounds (2-4) by an activity-guided approach using the TCF reporter (TOP) luciferase-based assay system. A fluorometric microculture cytotoxicity assay (FMCA) revealed that compound 1 was cytotoxic to AGS human gastric adenocarcinoma cells. The treatment of AGS cells with 1 decreased β-catenin levels and also inhibited its nuclear localization. The pretreatment of AGS cells with a proteasome inhibitor, either MG132 or epoxomicin, protected against the degradation of β-catenin induced by 1. The 1-induced degradation of β-catenin was also abrogated in the presence of pifithrin-α, an inhibitor of p53 transcriptional activity. Compound 1 inhibited TOP activity in AGS cells and downregulated the protein levels of cyclin D1, c-myc, and survivin. Compound 1 also sensitized AGS cells to tumor necrosis factor-related apoptosis ligand (TRAIL)-induced apoptosis by increasing the levels of the death receptors, DR4 and DR5, and decreasing the level of the antiapoptotic protein Bcl-2. Collectively, our results demonstrated that 1 induced the p53- and proteasome-dependent degradation of β-catenin, which resulted in the inhibition of TCF/β-catenin transcription in AGS cells. Furthermore, 1 enhanced apoptosis in TRAIL-resistant AGS when combined with TRAIL.

Matrine induces mitochondrial apoptosis in cisplatin-resistant non-small cell lung cancer cells via suppression of β-catenin/survivin signaling

Matrine is an alkaloid isolated from Sophora flavescens and shows anticancer activities. The present study was carried out to determine the cytotoxic effects of matrine on cisplatin-resistant non-small cell lung cancer (NSCLC) cells and the associated molecular mechanisms. Parental and cisplatin-resistant A549 and H460 NSCLC cells were treated with 1 or 2 g/l of matrine for 48 h, and cell viability and apoptosis were assessed. β-catenin-mediated transcriptional activity, mitochondrial membrane potential (ΔΨm) changes, activation of caspases, and survivin expression were examined. The effect of overexpression of survivin on the anticancer activity of matrine was investigated. Compared to the parental cells, cisplatin-resistant NSCLC cells showed increased β-catenin transcriptional activity. Matrine treatment resulted in a significant reduction in β-catenin activation and survivin expression in the cisplatin-resistant cells. Matrine caused apoptotic death in the cisplatin-resistant NSCLC cells, coupled with loss of ΔΨm and activation of caspase-9 and -3. Matrine-induced apoptosis of the cisplatin-resistant NSCLC cells was significantly reversed by overexpression of survivin. In conclusion, matrine exposure induces mitochondrial apoptosis in cisplatin-resistant NSCLC cells, which is largely mediated through inactivation of β-catenin/survivin signaling. Further investigation of the therapeutic benefit of matrine in overcoming cisplatin resistance in NSCLC is warranted.

EGCG inhibits proliferation, invasiveness and tumor growth by up-regulation of adhesion molecules, suppression of gelatinases activity, and induction of apoptosis in nasopharyngeal carcinoma cells

(-)-Epigallocatechin-3-gallate (EGCG), a major green tea polyphenol, has been shown to inhibit the proliferation of a variety of tumor cells. Epidemiological studies have shown that drinking green tea can reduce the incidence of nasopharyngeal carcinoma (NPC), yet the underlying mechanism is not well understood. In this study, the inhibitory effect of EGCG was tested on a set of Epstein Barr virus-negative and -positive NPC cell lines. Treatment with EGCG inhibited the proliferation of NPC cells but did not affect the growth of a non-malignant nasopharyngeal cell line, NP460hTert. Moreover, EGCG treated cells had reduced migration and invasive properties. The expression of the cell adhesion molecules E-cadherin and β-catenin was found to be up-regulated by EGCG treatment, while the down-regulation of matrix metalloproteinases (MMP)-2 and MMP-9 were found to be mediated by suppression of extracellular signal-regulated kinase (ERK) phosphorylation and AP-1 and Sp1 transactivation. Spheroid formation by NPC cells in suspension was significantly inhibited by EGCG. Oral administration of EGCG was capable of suppressing tumor growth in xenografted mice bearing NPC tumors. Treatment with EGCG was found to elevate the expression of p53 and p21, and eventually led to apoptosis of NPC cells via caspase 3 activation. The nuclear translocation of NF-κB and β-catenin was also suppressed by EGCG treatment. These results indicate that EGCG can inhibit the proliferation and invasiveness, and induce apoptosis, of NPC cells, making it a promising agent for chemoprevention or adjuvant therapy of NPC.

Natural compounds with Wnt signal modulating activity

This article highlights natural compounds that are reported to modulate the Wnt signalling activity. The plausible mechanisms of action of the natural Wnt modulators are also presented.

Blockade of CXCL12/CXCR4 signaling inhibits intrahepatic cholangiocarcinoma progression and metastasis via inactivation of canonical Wnt pathway

Background

Intrahepatic cholangiocarcinoma (IHCC) is the second most frequent primary malignant liver tumor following hepatocellular carcinoma. It is a highly fatal disease and has few therapeutics. The CXC chemokine ligand-12 (CXCL12)/CXC chemokine receptor type 4 (CXCR4) axis has been shown to be involved in tumorgenesis, proliferation, and angiogenesis in a variety of cancers including IHCC. However, its prognostic significance in IHCC is unclear. The purpose of this study was to examine the functional role of CXCR4 in the progression and metastasis of IHCC and explore the underlying mechanism.

Methods

The CXCR4 expression, overall survival, and the clinical characteristics including age, sex, differentiation degree, tumor size, vascular invasion, lymph node metastasis, TNM stage, and T stage were analyzed for 122 IHCC patients. Short hairpin RNA (shRNA) against CXCR4 was used to disrupt the CXCL12/CXCR4 signal transduction pathways in IHCC cell lines. In vitro assays, including CCK-8 assay, flow cytometry, and colony formation assay, and in vivo tumor formation assay were utilized to detect the cell phenotype of CXCR4 knockdown cells. Transwell and wound healing assays were used to examine the IHCC cell invasion and migration ability. The Wnt pathway was assessed by Western blot and β-Catenin/Tcf transcription reporter assay.

Results

We demonstrated that CXCR4 expression was closely correlated with IHCC progression and metastasis characteristics. The overall survival of patients with high CXCR4 expression was significantly lower than that of patients with low CXCR4 expression. Furthermore, we showed that the abrogation of CXCR4 had significantly negative influence on the IHCC cell phenotype, including in vitro cell proliferation, cell cycle, colony formation, cell invasion, and in vivo tumorigenicity. In addition, CXCR4 knockdown downregulated Wnt target genes and mesenchymal markers such as Vimentin and Slug.

Conclusions

In conclusion, our result shows that high CXCR4 expression is associated with IHCC progression and metastasis via the canonical Wnt pathway, suggesting that CXCR4 may serve as a promising therapeutic target for IHCC.

Downregulation of RIP140 in hepatocellular carcinoma promoted the growth and migration of the cancer cells

Hepatocellular carcinoma (HCC) is one of the most common malignancies with a poor response to chemotherapy. It is very important to identify novel diagnosis biomarkers and therapeutic targets. RIP140, a regulator of estrogen receptor, recently has been found to be involved in the tumorigenesis. However, its function in the progression of HCC remains poorly understood. Here, we found that the expression of RIP140 was downregulated in the HCC tissues. Moreover, overexpression of RIP140 in HCC cells inhibited cell proliferation and migration, while downregulation of RIP140 promoted the tumorigenicity of HCC cells in vitro and in vivo. Mechanistically, RIP140 interacted with beta-catenin and negatively regulated beta-catenin/TCF signaling. Taken together, our study suggests the suppressive roles of RIP140 in the pathogenesis of HCC.

[In situ analyses of molecular mechanisms of colorectal carcinogenesis]

The main signaling pathways of colorectal carcinogenesis encompass the classical adenoma-carcinoma sequence and the serrated route. In the classical adenoma-carcinoma sequence there are initially frequent mutations of the APC gene which lead to an activation of the WNT signaling pathway. When the WNT signaling pathway is activated β-catenin mediates the transcription of diverse factors which cause migration, invasion and proliferation of cells. Although APC mutations occur in all tumor cells, a heterogeneous distribution pattern of β-catenin is found in tumors and β-catenin also represents an important prognostic marker. A similar picture is found for γ-catenin which is expressed independently from β-catenin. Clearly more homogeneous is the expression of TCF4 and LEF1 which are the main binding partners of β-catenin and γ-catenin and are likewise important prognostic markers. The TRAIL signaling pathway is therapeutically interesting and within this pathway loss of the main receptors TRAIL-R1 and TRAIL-R2 is frequently found. Furthermore, the membranous localization of both factors correlates with a better overall survival. These results might be therapeutically relevant with respect to therapy with recombinant TRAIL molecules binding to TRAIL-R1 and TRAIL-R2. In the serrated route oncogen-induced senescence caused by mutations of the KRAS and BRAF oncogenes initially plays an important role. This senescence blockade is overcome by hypermethylation of the p16(INK4a) promoter and leads to the development of invasive tumors. The SIRT1 and c-Myc genes also contribute to progression of lesions in the serrated route and are activated through the RAS/RAF/MAPK-kinase signaling pathway as well as the WNT/β-catenin signaling pathway.

Involvement of RARRES3 in the regulation of Wnt proteins acylation and signaling activities in human breast cancer cells

The Wnt/β-catenin signaling pathway has emerged as a key regulator of complex biological processes, such as embryonic development, cell proliferation, cell fate decision and tumorigenesis. Recent studies have shown that the deregulation of Wnt/β-catenin signaling is frequently observed and leads to abnormal cell growth in human breast cancer cells. In this study, we identified a novel regulatory mechanism of Wnt/β-catenin signaling through RARRES3 that targets and modulates the acylation status of Wnt proteins and co-receptor low-density lipoprotein receptor-related protein 6, resulting in the suppression of epithelial-mesenchymal transition and cancer stem cell properties. Mutation of the conserved active site residues of RARRES3 indicates that RARRES3 serves as an acyl protein thioesterase that tethers its target proteins and modulates their acylation status. Furthermore, the functions of p53 in cell proliferation and Wnt/β-catenin signaling are significantly associated with the induction of RARRES3. Thus our findings provide a new insight into the molecular link between p53, protein acylation and Wnt/β-catenin signaling whereby RARRES3 plays a pivotal role in modulating the acylation status of signaling proteins.

The association between DNA copy number aberrations at chromosome 5q22 and gastric cancer

Background

Gastric cancer is common cancer. Discovering novel genetic biomarkers might help to identify high-risk individuals. Copy number variation (CNV) has recently been shown to influence risk for several cancers. The aim of the present study was sought to test the association between copy number at a variant region and GC.

Methods

A total of 110 gastric cancer patients and 325 healthy volunteers were enrolled in this study. We searched for a CNV and found a CNV (Variation 7468) containing part of the APC gene, the SRP19 gene and the REEP5 gene. We chose four probes targeting at APC-intron8, APC-exon9, SRP19 and REEP5 to interrogate this CNV. Specific Taqman probes labeled by different reporter fluorophores were used in a real-time PCR platform to obtain copy number. Both the original non-integer data and transformed integer data on copy number were used for analyses.

Results

Gastric caner patients had a lower non-integer copy number than controls for the APC-exon9 probe (Adjusted p = 0.026) and SRP19 probe (Adjusted p = 0.002). The analysis of integer copy number yielded a similar pattern although less significant (Adjusted p = 0.07 for APC-exon9 probe and Adjusted p = 0.02 for SRP19 probe).

Conclusions

Losses of a CNV at 5q22, especially in the DNA region surrounding APC-exon 9, may be associated with a higher risk of gastric cancer.