Noncanonical Wnt11 inhibits hepatocellular carcinoma cell proliferation and migration

Wnt signaling and tumors (Review)

Wnt signaling is a highly conserved evolutionary pathway that plays a key role in regulation of embryonic development, as well as tissue homeostasis and regeneration. Abnormalities in Wnt signaling are associated with tumorigenesis and development, leading to poor prognosis in patients with cancer. However, the pharmacological effects and mechanisms underlying Wnt signaling and its inhibition in cancer treatment remain unclear. In addition, potential side effects of inhibiting this process are not well understood. Therefore, the present review outlines the role of Wnt signaling in tumorigenesis, development, metastasis, cancer stem cells, radiotherapy resistance and tumor immunity. The present review further identifies inhibitors that target Wnt signaling to provide a potential novel direction for cancer treatment. This may facilitate early application of safe and effective drugs targeting Wnt signaling in clinical settings. An in-depth understanding of the mechanisms underlying inhibition of Wnt signaling may improve the prognosis of patients with cancer.

Biliary atresia: insights into mechanisms using a toxic model of the disease including Wnt and Hippo signaling pathways and microtubules

BACKGROUND

Mechanisms underlying bile duct injury in biliary atresia (BA) remain unclear and mechanisms of bile duct repair are unknown. This study aimed to explore the roles of microtubule instability and Wnt and Hippo signaling pathways in a biliatresone-induced BA model.

METHODS

Using primary murine neonatal cholangiocytes in both 2D and 3D cultures, and ex-vivo extra hepatic bile ducts (EHBD) which also has peri-cholangiocyte area, we analyzed injury and recovery processes. Injury was induced by the toxin biliatresone and recovery was induced by toxin wash-out.

RESULTS

Microtubule stabilizer paclitaxel prevented biliatresone-induced injury, both to cholangiocytes as well as reduced periductal αSMA stain, this process is mediated by decreased glutathione levels. RhoU and Wnt11 (Wnt signaling) and Pard6g and Amotl1 (Hippo signaling) are involved in both injury and recovery processes, with the latter acting upstream to Wnt signaling.

CONCLUSIONS

Early stages of biliatresone-induced EHBD injury in cholangiocytes and periductal structures are reversible. Wnt and Hippo signaling pathways play crucial roles in injury and recovery, providing insights into BA injury mechanisms and potential recovery avenues.

IMPACT

Microtubule stabilization prevents cholangiocyte injury and lumen obstruction in a toxic model of biliary atresia (biliatresone induced). Early stages of biliatresone-induced injury, affecting both cholangiocytes and periductal structures, are reversible. Both Wnt and Hippo signaling pathways play a crucial role in bile duct injury and recovery, with a noted interplay between the two. Understanding mechanisms of cholangiocyte recovery is imperative to unveil potential therapeutic avenues.

The evolving roles of Wnt signaling in stem cell proliferation and differentiation, the development of human diseases, and therapeutic opportunities

The evolutionarily conserved Wnt signaling pathway plays a central role in development and adult tissue homeostasis across species. Wnt proteins are secreted, lipid-modified signaling molecules that activate the canonical (β-catenin dependent) and non-canonical (β-catenin independent) Wnt signaling pathways. Cellular behaviors such as proliferation, differentiation, maturation, and proper body-axis specification are carried out by the canonical pathway, which is the best characterized of the known Wnt signaling paths. Wnt signaling has emerged as an important factor in stem cell biology and is known to affect the self-renewal of stem cells in various tissues. This includes but is not limited to embryonic, hematopoietic, mesenchymal, gut, neural, and epidermal stem cells. Wnt signaling has also been implicated in tumor cells that exhibit stem cell-like properties. Wnt signaling is crucial for bone formation and presents a potential target for the development of therapeutics for bone disorders. Not surprisingly, aberrant Wnt signaling is also associated with a wide variety of diseases, including cancer. Mutations of Wnt pathway members in cancer can lead to unchecked cell proliferation, epithelial-mesenchymal transition, and metastasis. Altogether, advances in the understanding of dysregulated Wnt signaling in disease have paved the way for the development of novel therapeutics that target components of the Wnt pathway. Beginning with a brief overview of the mechanisms of canonical and non-canonical Wnt, this review aims to summarize the current knowledge of Wnt signaling in stem cells, aberrations to the Wnt pathway associated with diseases, and novel therapeutics targeting the Wnt pathway in preclinical and clinical studies.

WNT ligands in non-small cell lung cancer: from pathogenesis to clinical practice

Non-small cell lung cancer (NSCLC) is the malignant tumor with the highest morbidity and leading cause of death worldwide, whereas its pathogenesis has not been fully elucidated. Although mutations in some crucial genes in WNT pathways such as β-catenin and APC are not common in NSCLC, the abnormal signal transduction of WNT pathways is still closely related to the occurrence and progression of NSCLC. WNT ligands (WNTs) are a class of secreted glycoproteins that activate WNT pathways through binding to their receptors and play important regulatory roles in embryonic development, cell differentiation, and tissue regeneration. Therefore, the abnormal expression or dysfunction of WNTs undoubtedly affects WNT pathways and thus participates in the pathogenesis of diseases. There are 19 members of human WNTs, WNT1, WNT2, WNT2b, WNT3, WNT3a, WNT4, WNT5a, WNT5b, WNT6, WNT7a, WNT7b, WNT8a, WNT8b, WNT9a, WNT9b, WNT10a, WNT10b, WNT11 and WNT16. The expression levels of WNTs, binding receptors, and activated WNT pathways are diverse in different tissue types, which endows the complexity of WNT pathways and multifarious biological effects. Although abundant studies have reported the role of WNTs in the pathogenesis of NSCLC, it still needs further study as therapeutic targets for lung cancer. This review will systematically summarize current research on human WNTs in NSCLC, from molecular pathogenesis to potential clinical practice.

Validation and analysis of expression, prognosis and immune infiltration of WNT gene family in non-small cell lung cancer

Early diagnosis and prognosis prediction of non-small cell lung cancer (NSCLC) have been challenging. Signaling cascades involving the Wingless-type (WNT) gene family play important biological roles and show prognostic value in various cancers, including NSCLC. On this basis, this study aimed to investigate the significance of WNTs in the prognosis and tumor immunity in NSCLC by comprehensive analysis. Expression and methylation levels of WNTs were obtained from the ONCOMINE, TIMER, and UALCAN. The dataset obtained from The Cancer Genome Atlas (TCGA) was utilized for prognostic analysis. cBioPortal was used to perform genetic alterations and correlation analysis of WNTs. R software was employed for functional enrichment and pathway analysis, partial statistics, and graph drawing. TRRUST was used to find key transcription factors. GEPIA was utilized for the analysis of expression, pathological staging, etc. Correlative analysis of immune infiltrates from TIMER. TISIDB was used for further immune infiltration validation analysis. Compared with that of normal tissues, WNT2/2B/3A/4/7A/9A/9B/11 expressions decreased, while WNT3/5B/6/7B/8B/10A/10B/16 expressions increased in lung adenocarcinoma (LUAD); WNT2/3A/7A/11 expressions were lessened, while WNT2B/3/5A/5B/6/7B/10A/10B/16 expressions were enhanced in squamous cell lung cancer (LUSC). Survival analysis revealed that highly expressed WNT2B and lowly expressed WNT7A predicted better prognostic outcomes in LUAD and LUSC. In the study of immune infiltration levels, WNT2, WNT9B, and WNT10A were positively correlated with six immune cells in LUAD; WNT1, WNT2, and WNT9B were positively correlated with six immune cells in LUSC, while WNT7B was negatively correlated. Our study indicated that WNT2B and WNT7A might have prognostic value in LUAD, and both of them might be important prognostic factors in LUSC and correlated to immune cell infiltration in LUAD and LUSC to a certain extent. Considering the prognostic value of WNT2B and WNT7A in NSCLC, we validated their mRNA and protein expression levels in NSCLC by performing qRT-PCR, western blot, and immunohistochemical staining on NSCLC pathological tissues and cell lines. This study may provide some direction for the subsequent exploration of the prognostic value of the WNTs and their role as biomarkers in NSCLC.

Noncanonical Wnt Signaling Promotes Myofibroblast Differentiation in Pulmonary Fibrosis

The Wnt/β-catenin pathway initiates a signaling cascade that is critical in cell differentiation and the normal development of multiple organ systems. The reactivation of this pathway has been documented in experimental and human idiopathic pulmonary fibrosis, wherein Wnt/β-catenin activation has been implicated in epithelial-cell repair. Furthermore, the canonical ligand Wnt3a is known to induce myofibroblast differentiation; however, the role of noncanonical Wnt ligands remains unclear. This study showed significantly higher levels of Wnt11 expression in cells from both patients with idiopathic pulmonary fibrosis and bleomycin-treated mice, as well as in TGFβ-treated mouse lung fibroblasts. Moreover, Wnt11 induced myofibroblast differentiation as manifested by increased α-SMA (ACTA2) expression, which was similar to that induced by canonical Wnt3a/β-catenin signaling. Further investigation revealed that Wnt11 induction of α-SMA was associated with the activation of JNK (c-Jun N-terminal kinase)/c-Jun signaling and was inhibited by a JNK inhibitor. The potential importance of this signaling pathway was supported by in vivo evidence showing significantly increased levels of Wnt11 and activated JNK in the lungs of mice with bleomycin-induced pulmonary fibrosis. Interestingly, fibroblasts did not express canonical Wnt3a, but treatment of these cells with exogenous Wnt3a induced endogenous Wnt11 and Wnt5a, resulting in repression of the Wnt3a/β-catenin target gene Axin2. These findings suggested that the noncanonical Wnt induction of myofibroblast differentiation mediated by the JNK/c-Jun pathway might play a significant role in pulmonary fibrosis, in addition to or in synergy with canonical Wnt3a/β-catenin signaling. Moreover, Wnt3a activation of noncanonical Wnt signaling might trigger a switch from canonical to noncanonical Wnt signaling to induce myofibroblast differentiation.

Bioinformatic analysis of RHO family of GTPases identifies RAC1 pharmacological inhibition as a new therapeutic strategy for hepatocellular carcinoma

OBJECTIVE

The RHO family of GTPases, particularly RAC1, has been linked with hepatocarcinogenesis, suggesting that their inhibition might be a rational therapeutic approach. We aimed to identify and target deregulated RHO family members in human hepatocellular carcinoma (HCC).

DESIGN

We studied expression deregulation, clinical prognosis and transcription programmes relevant to HCC using public datasets. The therapeutic potential of RAC1 inhibitors in HCC was study in vitro and in vivo. RNA-Seq analysis and their correlation with the three different HCC datasets were used to characterise the underlying mechanism on RAC1 inhibition. The therapeutic effect of RAC1 inhibition on liver fibrosis was evaluated.

RESULTS

Among the RHO family of GTPases we observed that RAC1 is upregulated, correlates with poor patient survival, and is strongly linked with a prooncogenic transcriptional programme. From a panel of novel RAC1 inhibitors studied, 1D-142 was able to induce apoptosis and cell cycle arrest in HCC cells, displaying a stronger effect in highly proliferative cells. Partial rescue of the RAC1-related oncogenic transcriptional programme was obtained on RAC1 inhibition by 1D-142 in HCC. Most importantly, the RAC1 inhibitor 1D-142 strongly reduce tumour growth and intrahepatic metastasis in HCC mice models. Additionally, 1D-142 decreases hepatic stellate cell activation and exerts an anti-fibrotic effect in vivo.

CONCLUSIONS

The bioinformatics analysis of the HCC datasets, allows identifying RAC1 as a new therapeutic target for HCC. The targeted inhibition of RAC1 by 1D-142 resulted in a potent antitumoural effect in highly proliferative HCC established in fibrotic livers.

Targeting myosin 1c inhibits murine hepatic fibrogenesis

Myosin 1c (Myo1c) is an unconventional myosin that modulates signaling pathways involved in tissue injury and repair. In this study, we observed that Myo1c expression is significantly upregulated in human chronic liver disease such as nonalcoholic steatohepatitis (NASH) and in animal models of liver fibrosis. High throughput data from the GEO-database identified similar Myo1c upregulation in mice and human liver fibrosis. Notably, transforming growth factor-β1 (TGF-β1) stimulation to hepatic stellate cells (HSCs), the liver pericyte and key cell type responsible for the deposition of extracellular matrix, upregulates Myo1c expression, whereas genetic depletion or pharmacological inhibition of Myo1c blunted TGF-β-induced fibrogenic responses, resulting in repression of α-smooth muscle actin (α-SMA) and collagen type I α 1 chain (Col1α1) mRNA. Myo1c deletion also decreased fibrogenic processes such as cell proliferation, wound healing response, and contractility when compared with vehicle-treated HSCs. Importantly, phosphorylation of mothers against decapentaplegic homolog 2 (SMAD2) and mothers against decapentaplegic homolog 3 (SMAD3) were significantly blunted upon Myo1c inhibition in GRX cells as well as Myo1c knockout (Myo1c-KO) mouse embryonic fibroblasts (MEFs) upon TGF-β stimulation. Using the genetic Myo1c-KO mice, we confirmed that Myo1c is critical for fibrogenesis, as Myo1c-KO mice were resistant to carbon tetrachloride (CCl4)-induced liver fibrosis. Histological and immunostaining analysis of liver sections showed that deposition of collagen fibers and α-SMA expression were significantly reduced in Myo1c-KO mice upon liver injury. Collectively, these results demonstrate that Myo1c mediates hepatic fibrogenesis by modulating TGF-β signaling and suggest that inhibiting this process may have clinical application in treating liver fibrosis.NEW & NOTEWORTHY The incidences of liver fibrosis are growing at a rapid pace and have become one of the leading causes of end-stage liver disease. Although TGF-β1 is known to play a prominent role in transforming cells to produce excessive extracellular matrix that lead to hepatic fibrosis, the therapies targeting TGF-β1 have achieved very limited clinical impact. This study highlights motor protein myosin-1c-mediated mechanisms that serve as novel regulators of TGF-β1 signaling and fibrosis.

Regulation of Wnt Signaling Pathways at the Plasma Membrane and Their Misregulation in Cancer

Wnt signaling is one of the key signaling pathways that govern numerous physiological activities such as growth, differentiation and migration during development and homeostasis. As pathway misregulation has been extensively linked to pathological processes including malignant tumors, a thorough understanding of pathway regulation is essential for development of effective therapeutic approaches. A prominent feature of cancer cells is that they significantly differ from healthy cells with respect to their plasma membrane composition and lipid organization. Here, we review the key role of membrane composition and lipid order in activation of Wnt signaling pathway by tightly regulating formation and interactions of the Wnt-receptor complex. We also discuss in detail how plasma membrane components, in particular the ligands, (co)receptors and extracellular or membrane-bound modulators, of Wnt pathways are affected in lung, colorectal, liver and breast cancers that have been associated with abnormal activation of Wnt signaling. Wnt-receptor complex components and their modulators are frequently misexpressed in these cancers and this appears to correlate with metastasis and cancer progression. Thus, composition and organization of the plasma membrane can be exploited to develop new anticancer drugs that are targeted in a highly specific manner to the Wnt-receptor complex, rendering a more effective therapeutic outcome possible.

Prognostic role of Wnt and Fzd gene families in acute myeloid leukaemia

Wnt-Fzd signalling pathway plays a critical role in acute myeloid leukaemia (AML) progression and oncogenicity. There is no study to investigate the prognostic value of Wnt and Fzd gene families in AML. Our study screened 84 AML patients receiving chemotherapy only and 71 also undergoing allogeneic haematopoietic stem cell transplantation (allo-HSCT) from the Cancer Genome Atlas (TCGA) database. We found that some Wnt and Fzd genes had significant positive correlations. The expression levels of Fzd gene family were independent of survival in AML patients. In the chemotherapy group, AML patients with high Wnt2B or Wnt11 expression had significantly shorter event-free survival (EFS) and overall survival (OS); high Wnt10A expressers had significantly longer OS than the low expressers (all P < .05), whereas, in the allo-HSCT group, the expression levels of Wnt gene family were independent of survival. We further found that high expression of Wnt10A and Wnt11 had independent prognostic value, and the patients with high Wnt10A and low Wnt11 expression had the longest EFS and OS in the chemotherapy group. Pathway enrichment analysis showed that genes related to Wnt10A, Wnt11 and Wnt 2B were mainly enriched in 'cell morphogenesis involved in differentiation', 'haematopoietic cell lineage', 'platelet activation, signalling and aggregation' and 'mitochondrial RNA metabolic process' signalling pathways. Our results indicate that high Wnt2B and Wnt11 expression predict poor prognosis, and high Wnt10A expression predicts favourable prognosis in AML, but their prognostic effects could be neutralized by allo-HSCT. Combined Wnt10A and Wnt11 may be a novel prognostic marker in AML.

An Overview of Potential Therapeutic Agents Targeting WNT/PCP Signaling

Since the discovery of the proto-oncogene Wnt1 (Int1) in 1982, WNT signaling has been identified as one of the most important pathways that regulates a wide range of fundamental developmental and physiological processes in multicellular organisms. The canonical WNT signaling pathway depends on the stabilization and translocation of β-catenin and plays important roles in development and homeostasis. The WNT/planar cell polarity (WNT/PCP) signaling, also known as one of the β-catenin-independent WNT pathways, conveys directional information to coordinate polarized cell behaviors. Similar to WNT/β-catenin signaling, disruption or aberrant activation of WNT/PCP signaling also underlies a variety of developmental defects and cancers. However, the pharmacological targeting of WNT/PCP signaling for therapeutic purposes remains largely unexplored. In this review, we briefly discuss WNT/PCP signaling in development and disease and summarize the known drugs/inhibitors targeting this pathway.

Wnt/β‑catenin signaling: Causes and treatment targets of drug resistance in colorectal cancer (Review)

Colorectal cancer (CRC) is the third most common malignant tumor in humans. Chemotherapy is used for the treatment of CRC. However, the effect of chemotherapy remains unsatisfactory due to drug resistance. Growing evidence has shown that the presence of highly metastatic tumor stem cells, regulation of non-coding RNAs and the tumor microenvironment contributes to drug resistance mechanisms in CRC. Wnt/β-catenin signaling mediates the chemoresistance of CRC in these three aspects. Therefore, the present study analyzed the abundant evidence of the contribution of Wnt/β-catenin signaling to the development of drug resistance in CRC and discussed its possible role in improving the chemosensitivity of CRC, which may provide guidelines for its clinical treatment.

The involvement of noncanonical Wnt signaling in cancers

Wnt signaling is one of the key cascades regulating normal tissue development and has been tightly associated with cancer. The Wnt signaling can be subdivided into two categories: canonical & noncanonical. Noncanonical Wnt signaling pathways mainly include Wnt/PCP (planar cell polarity) signaling and Wnt-cGMP (cyclic guanosine monophosphate) /Ca2+ signaling. It has been well studied by previous researches that noncanonical Wnt signaling regulates multiple cell functions including proliferation, differentiation, adhesion, polarity, motility, and migration. The aberrant activation or inhibition of noncanonical Wnt signaling is crucial in cancer progression, exerting both oncogenic and tumor-suppressive effects. Recent studies show the involvement of noncanonical Wnt in regulating cancer cell invasion, metastasis, metabolism, and inflammation. Here, we review current insights into novel components of non-canonical signalings and describe their involvement in various cancer types. We also summarize recent biological and clinical discoveries that outline non-canonical Wnt signaling in tumorigenesis. Finally, we provide an overview of current strategies to target non-canonical Wnt signaling in cancer and challenges that are associated with such approaches.

WNT/β-catenin signaling in the development of liver cancers

The WNT/β-catenin signaling pathway is a highly conserved and tightly controlled molecular mechanism that regulates embryonic development, cellular proliferation and differentiation. Of note, accumulating evidence has shown that the aberrant of WNT/β-catenin signaling promotes the development and/or progression of liver cancer, including hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), the two most prevalent primary liver tumours in adults. There are two different WNT signaling pathways have been identified, which were termed non-canonical and canonical pathways, the latter involving the activation of β-catenin. β-catenin, acting as an intracellular signal transducer in the WNT signaling pathway, is encoded by CTNNB1 and plays a critical role in tumorigenesis. In the past research, most liver tumors have mutations in genes encoding key components of the WNT/β-catenin signaling pathway. In addition, several of other signaling pathways also can crosswalk with β-catenin. In this review, we discuss the most relevant molecular mechanisms of action and regulation of WNT/β-catenin signaling in the development and pathophysiology of liver cancers, as well as in the development of therapeutics.

Mechanism of inhibiting proliferation of hepatocellular carcinoma Hepa1-6 cells by embryonic stem cell-conditioned medium

The present study aimed to investigate the antiproliferative effect of embryonic stem cell-conditioned medium (ESC-CM) on the mouse liver cancer Hepa1-6 cells in vitro. Furthermore, in order to elucidate the underlying molecular mechanism, the microRNAs (miRNAs) in ESC-CM associated with the inhibition of Hepa1-6 proliferation were identified. Following the co-culture of ESC-CM and Hepa1-6 in Transwell chambers, the proliferation, cell cycle, apoptosis and associated protein expression were determined in Hepal-6 cells. Moreover, miRNA array analysis was employed to identify differentially expressed miRNAs. Based on the differentially expressed miRNAs, the target genes and potential associated signaling pathways were determined. Finally, RT-qPCR was conducted to confirm the above results. The ESC-CM inhibited Hepal-6 cell proliferation and increased the percentage of cells at G₁ phase and decreased the percentage of cells at the G₂/M phase of the cell cycle. The expression of cyclin D1/cyclin-dependent kinase (CDK)4/CDK6 was decreased following co-culture, with no effect on cell apoptosis. Six significantly regulated miRNAs were identified and 423 putative target genes of these regulated miRNAs were predicted. Gene ontology analysis revealed the putative target genes to be associated with the ‘DNA replication (GO: 0006260)’ GO term, ‘apoptosis’ and ‘signal transduction’. The Kyoto Encyclopedia of Genes and Genomes analysis indicated that deregulated miRNAs were enriched in the Wnt signaling (KEGG entry: Map 04310) and Hippo signaling pathways (KEGG entry: Map 04390), pathways associated with cancer. Overall, the present study demonstrated the inhibition of Hepa1-6 cell line proliferation upon treatment with ESC-CM, by decreasing cell cycle-associated protein cyclin D1/CDK4/CDK6 expression and arresting cells in G₁ phase of the cell cycle, with no effect on cell apoptosis. Furthermore, the inhibition of proliferation by ESC-CM may be mediated by miRNAs that affect cell cycle-associated mRNAs and the Wnt signaling pathway.

Direct and Indirect Suppression of Scn5a Gene Expression Mediates Cardiac Na+ Channel Inhibition by Wnt Signalling

BACKGROUND

Myocardial infarction and heart failure are associated with reduced voltage-gated Na⁺ current (I_Na) that promotes arrhythmias and sudden deaths. We have previously shown that the Wnt/β-catenin signalling (Wnt signalling), which is active in heart disease, reduces cardiac I_Na, suggesting that Wnt signalling may be a potential therapeutic target. However, because Wnt signalling is required for the homeostasis of many noncardiac tissues, administration of Wnt inhibitors to heart patients would cause significant side effects. The present study aims to elucidate the molecular mechanisms of cardiac I_Na inhibition by Wnt, which would identify cardiac-specific therapeutic targets.

METHODS

Wnt signalling was activated in neonatal rat ventricular myocytes by Wnt3a protein. Adenovirus expressing Wnt3a was injected into the adult rat ventricle. CRISPR/Cas9 and chromatin immunoprecipitation were used for mechanistic studies.

RESULTS

Wnt signalling activation in neonatal rat ventricular myocytes reduced Na_v1.5 protein and Scn5a mRNA, but increased Tbx3, a known suppressor of Scn5a. Chromatin immunoprecipitation showed that Wnt signalling inhibits Scn5a expression through downstream mediator (TCF4) binding to both Tbx3 and Scn5a promoters. Overexpression or knockdown of Tbx3 directly modified Na_v1.5 and I_Na, whereas CRISPR/Cas9-induced mutations at TCF4 binding sites within the Scn5a promoter attenuated Wnt inhibition of Scn5a and Na_v1.5. In adult rat hearts, adenovirus expressing Wnt3a reduced Na_v1.5, increased QRS duration in electrocardiogram, and increased the susceptibility to ventricular tachycardia.

CONCLUSIONS

Wnt signalling inhibits the Na⁺ channel by direct and indirect (via Tbx3) suppression of Scn5a transcription. Strategies to block TCF4 binding to the Tbx3 and Scn5a promoters would represent novel strategies for cardiac-specific inhibition of the Wnt pathway to rescue I_Na and prevent sudden cardiac deaths.

WIF1 Suppresses the Generation of Suprabasal Cells in Acanthotic Skin and Growth of Basal Cell Carcinomas upon Forced Overexpression

We analyzed the role of WIF1 in normal and acanthotic epidermis of 12-O-tetradecanoylphorbol-13-acetate (TPA) or all-trans-retinoic acid (ATRA)-treated and basal cell carcinoma (BCC)-bearing mice. WIF1 protein is located in the follicular infundibulum and interfollicular epidermis (IFE) in murine back skin. Within the hyperplastic epidermis of TPA- or ATRA-treated or BCC-bearing murine skin, WIF1 and Keratin 10 overlap in Ki67^⁻ suprabasal layers, while basal epidermal layers expressing Ki67, and BCCs expressing Wif1 mRNA, are free of WIF1 protein. This is similar in human skin, with the exception that WIF1 protein is found in single Ki67^⁻ basal epidermal cells in normal skin and additionally in Ki67⁺ cells in acanthotic skin. Wif1-deficiency enhances acanthosis of the murine BCC-associated epidermis, which is accompanied by an increase of Ki67⁺ and of Sca-1⁺ basal cells. WIF1 overexpression in allografted BCC-derived keratinocytes prevents growth and keratinization, involving enhanced phosphorylation of protein kinase C and extracellular signal-regulated kinase 1 and arguably factors secreted by the in vivo environment. In summary, WIF1 protein marks suprabasal layers in the normal IFE. It is also present in the epidermis overlaying BCCs where it diminishes proliferation of basal cells and production of differentiating suprabasal cells. In addition, WIF1 can prevent proliferation and keratinization of BCC-related keratinocytes.

Lgr5 in cancer biology: functional identification of Lgr5 in cancer progression and potential opportunities for novel therapy

Cancer remains one of the leading lethal diseases worldwide. Identifying biomarkers of cancers might provide insights into the strategies for the development of novel targeted anti-cancer therapies. Leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) has been recently discovered as a candidate marker of cancer stem cell populations. Aberrant increased expression of Lgr5 may represent one of the most common molecular alterations in some human cancers, leading to long-term potentiation of canonical Wnt/β-catenin signaling. On the other hand, however, Lgr5-mediated suppression in canonical Wnt/β-catenin signaling has also been reported in certain cancers, such as B cell malignancies. Until now, therapeutic approaches targeting Lgr5-associated signaling axis are not yet clinically available. Increasing evidence have indicated that endogenous Lgr5+ cell population is implicated in tumor initiation, progression, and metastasis. This review is to summarize our current knowledge about the importance of Lgr5 in cancer biology and the underlying molecular mechanisms of Lgr5-mediated tumor-promoting/suppressive activities, as well as potentially useful preventive strategies in treating tumor. Therefore, targeted therapeutic modulation of Lgr5+ cancer cell population by targeting Wnt/β-catenin signaling through targeted drug delivery system or targeted genome editing might be promising for potential novel anti-cancer treatments. Simultaneously, combination of therapeutics targeting both Lgr5+ and Lgr5- cancer cells may deserve further consideration considering the plasticity of cancer cells. Also, a more specific targeting of cancer cells using double biomarkers may be much safer and more effective for anti-cancer therapy.

Wnt11 alters integrin and cadherin expression by ovarian cancer spheroids and inhibits tumorigenesis and metastasis

The present study investigated the role of Wnt11 in multicellular tumor spheroid-like structures (MCTS) ovarian cancer cell proliferation, migration and invasion in vitro and in vivo tumorigenesis and metastasis in xenograft nude mice model. Moreover, samples from human serous ovarian cancer (SOC) were used to assess the association of Wnt11 with integrins and cadherins. The data showed that Wnt11 overexpressing SKOV-3 cells became more compact accompanied by increased expression of E-and N-cadherin and lower expression of EpCAM and CD44. The α5, β2, β3 and β6 integrin subunits expression levels were significantly reduced in Wnt11 overexpressing cells accompanied with significantly reduced disaggregation of Wnt11 overexpressing SKOV-3 MCTS on ECM components. Moreover, Wnt11 overexpressing SKOV-3 MCTS showed decreased migration, invasion as well as no tumor growth and metastasis in vivo. We found that Wnt11 significantly and negatively correlated with ITGB2, ITGB6, and EpCAM and positively with CDH-1 in high-grade SOC specimens. Our results suggest that Wnt11 impedes MCTS attachment to ECM components and therefore can affect ovarian cancer progression.

The biochemistry, signalling and disease relevance of RYK and other WNT-binding receptor tyrosine kinases

The receptor tyrosine kinases (RTKs) are a well-characterized family of growth factor receptors that have central roles in human disease and are frequently therapeutically targeted. The RYK, ROR, PTK7 and MuSK subfamilies make up an understudied subset of WNT-binding RTKs. Numerous developmental, stem cell and pathological roles of WNTs, in particular WNT5A, involve signalling via these WNT receptors. The WNT-binding RTKs have highly context-dependent signalling outputs and stimulate the β-catenin-dependent, planar cell polarity and/or WNT/Ca²⁺ pathways. RYK, ROR and PTK7 members have a pseudokinase domain in their intracellular regions. Alternative signalling mechanisms, including proteolytic cleavage and protein scaffolding functions, have been identified for these receptors. This review explores the structure, signalling, physiological and pathological roles of RYK, with particular attention paid to cancer and the possibility of therapeutically targeting RYK. The other WNT-binding RTKs are compared with RYK throughout to highlight the similarities and differences within this subset of WNT receptors.

Piezo2 protein: A novel regulator of tumor angiogenesis and hyperpermeability

Angiogenesis is important for invasive tumor growth and metastasis. Its inhibition is a promising tactic for limiting tumor progression. Here, we showed that Piezo2 knockdown led to decreased glioma angiogenesis and reduced vascular hyperpermeability. Piezo2 was highly expressed in tumor endothelial cells, and its knockdown suppressed vascular leakage and tumor angiogenesis. In a retinal vasculature development assay, corneal angiogenesis assay and a modified Miles assay, Piezo2 knockdown obviously decreased angiogenesis and vascular hyperpermeability. In vitro assays revealed that Piezo2 knockdown inhibited endothelial cell proliferation, migration, and tube formation. Moreover, In vitro co-culture system assay showed that Piezo2 knockdown in endothelial cells suppressed cell proliferation, migration, and invasion of glioma tumor cells. Piezo2 could regulate glioma angiogenesis via Ca²⁺/Wnt11/β-catenin signaling in endothelial cells. Taken together, these studies provide the evidence for Piezo2 as a critical regulator of tumor angiogenesis and vascular permeability.

Cellular and molecular mechanisms underlying planar cell polarity pathway contributions to cancer malignancy

While the mutational activation of oncogenes drives tumor initiation and growth by promoting cellular transformation and proliferation, increasing evidence suggests that the subsequent re-engagement of largely dormant developmental pathways contributes to cellular phenotypes associated with the malignancy of solid tumors. Genetic studies from a variety of model organisms have defined many of the components that maintain epithelial planar cell polarity (PCP), or cellular polarity in the axis orthogonal to the apical-basal axis. These same components comprise an arm of non-canonical Wnt signaling that mediates cell motility events such as convergent extension movements essential to proper development. In this review, we summarize the increasing evidence that the Wnt/PCP signaling pathway plays active roles in promoting the proliferative and migratory properties of tumor cells, emphasizing the importance of subcellular localization of PCP components and protein-protein interactions in regulating cellullar properties associated with malignancy. Specifically, we discuss the increased expression of Wnt/PCP pathway components in cancer and the functional consequences of aberrant pathway activation, focusing on Wnt ligands, Frizzled (Fzd) receptors, the tetraspanin-like proteins Vangl1 and Vangl2, and the Prickle1 (Pk1) scaffold protein. In addition, we discuss negative regulation of the Wnt/PCP pathway, with particular emphasis on the Nrdp1 E3 ubiquitin ligase. We hypothesize that engagement of the Wnt/PCP pathway after tumor initiation drives malignancy by promoting cellular proliferation and invasiveness, and that the ability of Wnt/PCP signaling to supplant oncogene addiction may contribute to tumor resistance to oncogenic pathway-directed therapeutic agents.

Pivotal roles of glycogen synthase-3 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers in the world, and represents the second most frequently cancer and third most common cause of death from cancer worldwide. At advanced stage, HCC is a highly aggressive tumor with a poor prognosis and with very limited response to common therapies. Therefore, there is still the need for new effective and well-tolerated therapeutic strategies. Molecular-targeted therapies hold promise for HCC treatment. One promising molecular target is the multifunctional serine/threonine kinase glycogen synthase kinase 3 (GSK-3). The roles of GSK-3β in HCC remain controversial, several studies suggested a possible role of GSK-3β as a tumor suppressor gene in HCC, whereas, other studies indicate that GSK-3β is a potential therapeutic target for this neoplasia. In this review, we will focus on the different roles that GSK-3 plays in HCC and its interaction with signaling pathways implicated in the pathogenesis of HCC, such as Insulin-like Growth Factor (IGF), Notch, Wnt/β-catenin, Hedgehog (HH), and TGF-β pathways. In addition, the pivotal roles of GSK3 in epithelial-mesenchymal transition (EMT), invasion and metastasis will be also discussed.

Wnt proteins contribute to neuromuscular junction formation through distinct signaling pathways

Understanding the developmental steps that shape formation of the neuromuscular junction (NMJ) connecting motoneurons to skeletal muscle fibers is crucial. Wnt morphogens are key players in the formation of this specialized peripheral synapse, but their individual and collaborative functions and downstream pathways remain poorly understood at the NMJ. Here, we demonstrate through Wnt4 and Wnt11 gain-of-function studies in cell culture or in mice that Wnts enhance acetylcholine receptor (AChR) clustering and motor axon outgrowth. By contrast, loss of Wnt11 or Wnt-dependent signaling in vivo decreases AChR clustering and motor nerve terminal branching. Both Wnt4 and Wnt11 stimulate AChR mRNA levels and AChR clustering downstream of activation of the β-catenin pathway. Strikingly, Wnt4 and Wnt11 co-immunoprecipitate with Vangl2, a core component of the planar cell polarity (PCP) pathway, which accumulates at embryonic NMJs. Moreover, mice bearing a Vangl2 loss-of-function mutation (loop-tail) exhibit fewer AChR clusters and overgrowth of motor axons bypassing AChR clusters. Together, our results provide genetic and biochemical evidence that Wnt4 and Wnt11 cooperatively contribute to mammalian NMJ formation through activation of both the canonical and Vangl2-dependent core PCP pathways.

Aberrant regulation of Wnt signaling in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most lethal malignancies in the world. Several signaling pathways, including the wingless/int-1 (Wnt) signaling pathway, have been shown to be commonly activated in HCC. The Wnt signaling pathway can be triggered via both catenin β1 (CTNNB1)-dependent (also known as “canonical”) and CTNNB1-independent (often referred to as “non-canonical”) pathways. Specifically, the canonical Wnt pathway is one of those most frequently reported in HCC. Aberrant regulation from three complexes (the cell-surface receptor complex, the cytoplasmic destruction complex and the nuclear CTNNB1/T-cell-specific transcription factor/lymphoid enhancer binding factor transcriptional complex) are all involved in HCC. Although the non-canonical Wnt pathway is rarely reported, two main non-canonical pathways, Wnt/planar cell polarity pathway and Wnt/Ca²⁺ pathway, participate in the regulation of hepatocarcinogenesis. Interestingly, the canonical Wnt pathway is antagonized by non-canonical Wnt signaling in HCC. Moreover, other signaling cascades have also been demonstrated to regulate the Wnt pathway through crosstalk in HCC pathogenesis. This review provides a perspective on the emerging evidence that the aberrant regulation of Wnt signaling is a critical mechanism for the development of HCC. Furthermore, crosstalk between different signaling pathways might be conducive to the development of novel molecular targets of HCC.

Wnt Signaling in Cell Motility and Invasion: Drawing Parallels between Development and Cancer

The importance of canonical and non-canonical Wnt signal transduction cascades in embryonic development and tissue homeostasis is well recognized. The aberrant activation of these pathways in the adult leads to abnormal cellular behaviors, and tumor progression is frequently a consequence. Here we discuss recent findings and analogies between Wnt signaling in developmental processes and tumor progression, with a particular focus on cell motility and matrix invasion and highlight the roles of the ARF (ADP-Ribosylation Factor) and Rho-family small GTP-binding proteins. Wnt-regulated signal transduction from cell surface receptors, signaling endosomes and/or extracellular vesicles has the potential to profoundly influence cell movement, matrix degradation and paracrine signaling in both development and disease.

Expression of Wnt11 and Rock2 in esophageal squamous cell carcinoma by activation of the WNT/PCP pathway and its clinical significance

The purpose of this study was to investigate the relation between expression of Wnt11, Rho-associated protein kinase 2 (Rock2), and its clinical characteristics in esophageal squamous cell carcinoma (ESCC). Expression of Wnt11 and Rock2 protein was examined by using immunohistochemistry that contained 260 paraffin-embedded specimens of ESCC and its adjacent normal tissues; expression of Wnt11 and Rock2 protein was verified by Western-blotting that contained 20 specimens of ESCC and its adjacent normal tissues. The positive rates of Wnt11 protein in normal esophageal epithelium tissue was 29.8% and in esophageal carcinomas tissue was 31.9%; there was no significant difference between the two groups(P>0.05); The positive rates of Rock2 protein in normal esophageal epithelium tissue was 12.3% and in esophageal carcinomas tissues was 56.5%, there was a significant difference between the two groups (p<0.05). The expression of Rock2 protein was significantly related with the invasion of vascular and there was no significantly difference between the expression of Rock2 protein and ESCC patients' tumor location, differentiation, T stage, and lymph node metastases. The abnormal expression of Rock2 protein may promote tumor cell invasion.

Aberrant activation of Wnt/β-catenin signaling drives proliferation of bone sarcoma cells

Bone sarcomas such as osteosarcoma and chondrosarcoma are frequently refractory to conventional chemotherapy and radiotherapy that exhibit poor prognosis. The Wnt signaling are evolutionarily conserved and implicated in cell proliferation and sarcomagenesis. However, the potential role of the Wnt signaling in bone sarcomas is still unclear. Here we demonstrate aberrant activation of Wnt/β-catenin signaling in bone sarcoma cells, involving an autocrine Wnt signaling loop with upregulation of specific Wnt ligands and receptors. Activation of Wnt/β-catenin signaling with Wnt3a or GSK-3β inhibitor drives the proliferation of bone sarcoma cells, whereas downregulation of activated Wnt signaling with dnTCF4 or siLEF1 suppresses bone sarcoma proliferation and induces cell cycle arrest. Taken together, our findings establish the evidence that aberrant activation of Wnt/β-catenin pathway involving an autocrine Wnt singaling drives the proliferation of bone sarcoma cells, and identify the autocrine activation of the Wnt/β-catenin signaling as a potential novel therapeutic target for bone sarcomas.

Wnt-11 overexpression promoting the invasion of cervical cancer cells

Wnt-11 is a positive regulator of the Wnt signaling pathway, which plays a crucial role in carcinogenesis. However, Wnt-11 expression in cervical cancer has not been well investigated. The aim of this study was to investigate the role of Wnt-11 in cervical tumor proliferation and invasion. This study examined 24 normal cervical squamous epithelia, 29 cervical intraepithelial neoplasia (CIN), and 78 cervical cancer samples. The expression of Wnt-11 was investigated by immunohistochemistry and quantitative reverse transcription-polymerase chain reaction analysis. The expression of the high-risk human papilloma virus (HR-HPV) E6 oncoprotein was also investigated by immunohistochemistry. In addition, the expression of Wnt-11, HR-HPV E6, JNK-1, phosphorylated JNK-1(P-JNK1), and β-catenin was examined by western blot analysis following Wnt-11 knockdown or overexpression in HeLa or SiHa cells, respectively. The promotion of cervical cancer cell proliferation and invasion was investigated using the cell counting kit-8 and Matrigel invasion assay, respectively. Wnt-11 and HR-HPV E6 expression increased in a manner that corresponded with the progression of cervical cancer and was significantly correlated with the International Federation of Gynecology and Obstetrics cancer stage, lymph node metastasis, tumor size, and HPV infection. Wnt-11 protein expression was positively associated with HR-HPV E6 protein expression in all 78 cervical cancer samples (P < 0.001). Furthermore, Wnt-11 was positively associated with P-JNK1 expression and promoted cervical cancer cell proliferation and invasion. These observations suggest that the increased Wnt-11 expression observed in cervical cancer cells may lead to the phosphorylation and activation of JNK-1 and significantly promote tumor cell proliferation and cell migration/invasion through activation of the Wnt/JNK pathway. Consequently, Wnt-11 may serve as a novel target for cervical cancer therapy.

A crosstalk between TGF-β/Smad3 and Wnt/β-catenin pathways promotes vascular smooth muscle cell proliferation

RATIONALE

Endovascular interventions performed for atherosclerotic lesions trigger excessive vascular smooth muscle cell (SMC) proliferation leading to intimal hyperplasia. Our previous studies show that following endovascular injury, elevated TGF-β/Smad3 promotes SMC proliferation and intimal hyperplasia. Furthermore in cultured SMCs, elevated TGF-β/Smad3 increases the expression of several Wnt genes. Here we investigate a crosstalk between TGF-β/Smad3 and Wnt/β-catenin signaling and its role in SMC proliferation.

METHODS AND RESULTS

To mimic TGF-β/Smad3 up-regulation in vivo, rat aortic SMCs were treated with Smad3-expressing adenovirus (AdSmad3) or AdGFP control followed by stimulation with TGF-β1 (or solvent). AdSmad3/TGF-β treatment up-regulated Wnt2b, Wnt4, Wnt5a, Wnt9a, and Wnt11 (confirmed by qRT-PCR and ELISA), and also increased β-catenin protein as detected by Western blotting. Blocking Wnt signaling using a Frizzled receptor inhibitor (Niclosamide) abolished TGF-β/Smad3-induced β-catenin stabilization. Increasing β-catenin through degradation inhibition (using SKL2001) or by adenoviral expression enhanced SMC proliferation. Furthermore, application of recombinant Wnt2b, Wnt4, Wnt5a, or Wnt9a, but not Wnt11, stabilized β-catenin and stimulated SMC proliferation as well. In addition, increased β-catenin was found in the neointima of injured rat carotid artery where TGF-β and Smad3 are known to be up-regulated.

CONCLUSIONS

These results suggest a novel mechanism whereby elevated TGF-β/Smad3 stimulates the secretion of canonical Wnts which in turn enhances SMC proliferation through β-catenin stabilization. This crosstalk between TGF-β/Smad3 and Wnt/β-catenin canonical pathways provides new insights into the pathophysiology of vascular SMCs linked to intimal hyperplasia.

Transcriptome-Wide Analysis of Hepatitis B Virus-Mediated Changes to Normal Hepatocyte Gene Expression

Globally, a chronic hepatitis B virus (HBV) infection remains the leading cause of primary liver cancer. The mechanisms leading to the development of HBV-associated liver cancer remain incompletely understood. In part, this is because studies have been limited by the lack of effective model systems that are both readily available and mimic the cellular environment of a normal hepatocyte. Additionally, many studies have focused on single, specific factors or pathways that may be affected by HBV, without addressing cell physiology as a whole. Here, we apply RNA-seq technology to investigate transcriptome-wide, HBV-mediated changes in gene expression to identify single factors and pathways as well as networks of genes and pathways that are affected in the context of HBV replication. Importantly, these studies were conducted in an ex vivo model of cultured primary hepatocytes, allowing for the transcriptomic characterization of this model system and an investigation of early HBV-mediated effects in a biologically relevant context. We analyzed differential gene expression within the context of time-mediated gene-expression changes and show that in the context of HBV replication a number of genes and cellular pathways are altered, including those associated with metabolism, cell cycle regulation, and lipid biosynthesis. Multiple analysis pipelines, as well as qRT-PCR and an independent, replicate RNA-seq analysis, were used to identify and confirm differentially expressed genes. HBV-mediated alterations to the transcriptome that we identified likely represent early changes to hepatocytes following an HBV infection, suggesting potential targets for early therapeutic intervention. Overall, these studies have produced a valuable resource that can be used to expand our understanding of the complex network of host-virus interactions and the impact of HBV-mediated changes to normal hepatocyte physiology on viral replication.

Chronic infection with the hepatitis B virus (HBV) is the leading global cause of primary liver cancer; however, therapeutics for the treatment of chronic HBV are limited in both scope and efficacy. Infection with HBV results in an incompletely understood, complex network of host-virus interactions. To attempt to better understand these interactions, we assessed HBV-mediated changes to normal hepatocyte gene expression on a transcriptome-wide scale. By identifying gene expression that is altered by HBV, we were able to demonstrate that HBV affects multiple cellular signaling pathways that previously have been associated with carcinogenesis. As most HBV-related studies have investigated either late-stage changes in hepatocyte physiology or looked at cellular changes on a more narrow scale, our results represent an important advancement towards identifying early events associated with HBV replication, upstream of the development of HBV-associated disease. Additionally, our studies allowed us to characterize transcriptome changes that occur in a primary hepatocyte culture model, an important advancement in the confirmation of this commonly used model system as a biologically relevant alternative to transformed cell lines.

Induction of WNT11 by hypoxia and hypoxia-inducible factor-1α regulates cell proliferation, migration and invasion

Changes in cellular oxygen tension play important roles in physiological processes including development and pathological processes such as tumor promotion. The cellular adaptations to sustained hypoxia are mediated by hypoxia-inducible factors (HIFs) to regulate downstream target gene expression. With hypoxia, the stabilized HIF-α and aryl hydrocarbon receptor nuclear translocator (ARNT, also known as HIF-β) heterodimer bind to hypoxia response elements (HREs) and regulate expression of target genes. Here, we report that WNT11 is induced by hypoxia in many cell types, and that transcription of WNT11 is regulated primarily by HIF-1α. We observed induced WNT11 expression in the hypoxic area of allograft tumors. In addition, in mice bearing orthotopic malignant gliomas, inhibition with bevacizumab of vascular endothelial growth factor, which is an important stimulus for angiogenesis, increased nuclear HIF-1α and HIF-2α, and expression of WNT11. Gain- and loss-of-function approaches revealed that WNT11 stimulates proliferation, migration and invasion of cancer-derived cells, and increases activity of matrix metalloproteinase (MMP)-2 and 9. Since tumor hypoxia has been proposed to increase tumor aggressiveness, these data suggest WNT11 as a possible target for cancer therapies, especially for tumors treated with antiangiogenic therapy.

Weevil endosymbiont dynamics is associated with a clamping of immunity

BACKGROUND

Insects subsisting on nutritionally unbalanced diets have evolved long-term mutualistic relationships with intracellular symbiotic bacteria (endosymbionts). The endosymbiont population load undergoes changes along with insect development. In the cereal weevil Sitophilus oryzae, the midgut endosymbionts Sodalis pierantonius drastically multiply following adult metamorphosis and rapidly decline until total elimination when the insect achieves its cuticle synthesis. Whilst symbiont load was shown to timely meet insect metabolic needs, little is known about the host molecular and immune processes underlying this dynamics.

METHODS

We performed RNA sequencing analysis on weevil midguts at three representative phases of the endosymbiont dynamics (i.e. increase, climax and decrease). To screen genes which transcriptional changes are specifically related to symbiont dynamics and not to the intrinsic development of the midgut, we further have monitored by RT-qPCR sixteen gene transcript levels in symbiotic and artificially non-symbiotic (aposymbiotic) weevils. We also localized the endosymbionts during the elimination process by fluorescence microscopy.

RESULTS

Functional analysis of the host differentially expressed genes by RNA sequencing showed that the main transcriptional changes occur during endosymbiont growth phase and affect cell proliferation, apoptosis, autophagy, phagocytosis, and metabolism of fatty acids and nucleic acids. We also showed that symbiont dynamics alters the expression of several genes involved in insect development. Our results strengthened the implication of apoptosis and autophagy processes in symbiont elimination and recycling. Remarkably, apart from the coleoptericin A that is known to target endosymbionts and controls their division and location, no gene coding antimicrobial peptide was upregulated during the symbiont growth and elimination phases.

CONCLUSION

We show that endosymbiont dynamics parallels numerous transcriptional changes in weevil developing adults and affects several biological processes, including metabolism and development. It also triggers cell apoptosis, autophagy and gut epithelial cell swelling and delamination. Strikingly, immunity is repressed during the whole process, presumably avoiding tissue inflammation and allowing insects to optimize nutrient recovery from recycled endosymbiont.

Restoration of Wnt/β-catenin signaling attenuates alcoholic liver disease progression in a rat model

BACKGROUND & AIMS

Alcoholic liver disease (ALD) is characterized by the development of fatty liver, alcoholic hepatitis, fibrosis and cirrhosis. However, the underlying mechanism(s) associated with progression remains elusive. Pro-inflammatory cytokines have been implicated in ALD progression due to pro-apoptotic effects on hepatocytes. Wnt/β-catenin signaling recently has been shown to promote inflammation and apoptosis, suggesting that activation of this signaling pathway may modulate ALD progression. The current study was designed to test whether pharmacological activation of Wnt/β-catenin signaling altered ALD development and progression in a rat model.

METHODS

Adult male Long Evans rats were fed with isocaloric liquid diets containing 0% or 37% ethanol for 8 weeks, and also treated with Wnt agonist during the last 3 weeks of the feeding regimen. Liver and blood samples were subjected to histology, TUNEL assay, immunoblot analysis, real-time quantitative PCR, and alanine transaminase (ALT) assay.

RESULTS

Wnt/β-catenin signaling was negatively correlated with Foxo3A expression and reduced steatosis, cellular injury and apoptosis in ALD rats. Mutation experiments demonstrated that Foxo3A was critical for modulating these effects. Activation of Wnt/β-catenin signaling suppressed Foxo3A-induced apoptosis through upregulation of serum/glucocorticoid regulated kinase 1 (SGK1). Moreover, pharmacological restoration of Wnt/β-catenin signaling reduced ALD progression in vivo.

CONCLUSIONS

Wnt/β-catenin signaling plays a protective role in ALD progression via antagonizing Foxo3A-induced apoptosis, and activation of the Wnt/β-catenin signaling cascade attenuates ALD progression.

Myoepithelial and luminal breast cancer cells exhibit different responses to all-trans retinoic acid

PURPOSE

Breast cancer is the leading cause of death among women worldwide. The exact role of luminal epithelial (LEP) and myoephitelial (MEP) cells in breast cancer development is as yet unclear, as also how retinoids may affect their behaviour. Here, we set out to evaluate whether retinoids may differentially regulate cell type-specific processes associated with breast cancer development using the bi-cellular LM38-LP murine mammary adenocarcinoma cell line as a model.

MATERIALS AND METHODS

The bi-cellular LM38-LP murine mammary cell line was used as a model throughout all experiments. LEP and MEP subpopulations were separated using inmunobeads, and the expression of genes known to be involved in epithelial to mysenchymal transition (EMT) was assessed by qPCR after all-trans retinoic acid (ATRA) treatment. In vitro invasive capacities of LM38-LP cells were evaluated using 3D Matrigel cultures in conjunction with confocal microscopy. Also, in vitro proliferation, senescence and apoptosis characteristics were evaluated in the LEP and MEP subpopulations after ATRA treatment, as well as the effects of ATRA treatment on the clonogenic, adhesive and invasive capacities of these cells. Mammosphere assays were performed to detect stem cell subpopulations. Finally, the orthotopic growth and metastatic abilities of LM38-LP monolayer and mammosphere-derived cells were evaluated in vivo.

RESULTS

We found that ATRA treatment modulates a set of genes related to EMT, resulting in distinct gene expression signatures for the LEP or MEP subpopulations. We found that the MEP subpopulation responds to ATRA by increasing its adhesion to extracellular matrix (ECM) components and by reducing its invasive capacity. We also found that ATRA induces apoptosis in LEP cells, whereas the MEP compartment responded with senescence. In addition, we found that ATRA treatment results in smaller and more organized LM38-LP colonies in Matrigel. Finally, we identified a third subpopulation within the LM38-LP cell line with stem/progenitor cell characteristics, exhibiting a partial resistance to ATRA.

CONCLUSIONS

Our results show that the luminal epithelial (LEP) and myoephitelial (MEP) mammary LM38-P subpopulations respond differently to ATRA, i.e., the LEP subpopulation responds with increased cell cycle arrest and apoptosis and the MEP subpopulation responds with increased senescence and adhesion, thereby decreasing its invasive capacity. Finally, we identified a third subpopulation with stem/progenitor cell characteristics within the LM38-LP mammary adenocarcinoma cell line, which appears to be non-responsive to ATRA.

A review of crosstalk between MAPK and Wnt signals and its impact on cartilage regeneration

Chondrogenesis is a developmental process that is controlled and coordinated by many growth and differentiation factors, in addition to environmental factors that initiate or suppress cellular signaling pathways and the transcription of specific genes in a temporal-spatial manner. As key signaling molecules in regulating cell proliferation, homeostasis and development, both mitogen-activated protein kinases (MAPK) and the Wnt family participate in morphogenesis and tissue patterning, playing important roles in skeletal development, especially chondrogenesis. Recent findings suggest that both signals are also actively involved in arthritis and related diseases. Despite the implication that crosstalk between MAPK and Wnt signaling has a significant function in cancer, few studies have summarized this interaction and its regulation of chondrogenesis. In this review, we focus on MAPK and Wnt signaling, referencing their relationships in various types of cells and particularly to their influence on chondrogenesis and cartilage development. We also discuss the interactions between MAPK and Wnt signaling with respect to cartilage-related diseases such as osteoarthritis and explore potential therapeutic targets for disease treatments.

The roles of transforming growth factor-β, Wnt, Notch and hypoxia on liver progenitor cells in primary liver tumours (Review)

Primary liver tumours have a high incidence and mortality. The most important forms are hepatocellular carcinoma and intrahepatic cholangiocarcinoma, both can occur together in the mixed phenotype hepatocellular-cholangiocarcinoma. Liver progenitor cells (LPCs) are bipotential stem cells activated in case of severe liver damage and are capable of forming both cholangiocytes and hepatocytes. Possibly, alterations in Wnt, transforming growth factor-β, Notch and hypoxia pathways in these LPCs can cause them to give rise to cancer stem cells, capable of driving tumourigenesis. In this review, we summarize and discuss current knowledge on the role of these pathways in LPC activation and differentiation during hepatocarcinogenesis.

Wnt signaling and hepatocarcinogenesis: molecular targets for the development of innovative anticancer drugs

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer death worldwide. HCC can be cured by radical therapies if early diagnosis is done while the tumor has remained of small size. Unfortunately, diagnosis is commonly late when the tumor has grown and spread. Thus, palliative approaches are usually applied such as transarterial intrahepatic chemoembolization and sorafenib, an anti-angiogenic agent and MAP kinase inhibitor. This latter is the only targeted therapy that has shown significant, although moderate, efficiency in some individuals with advanced HCC. This highlights the need to develop other targeted therapies, and to this goal, to identify more and more pathways as potential targets. The Wnt pathway is a key component of a physiological process involved in embryonic development and tissue homeostasis. Activation of this pathway occurs when a Wnt ligand binds to a Frizzled (FZD) receptor at the cell membrane. Two different Wnt signaling cascades have been identified, called non-canonical and canonical pathways, the latter involving the β-catenin protein. Deregulation of the Wnt pathway is an early event in hepatocarcinogenesis and has been associated with an aggressive HCC phenotype, since it is implicated both in cell survival, proliferation, migration and invasion. Thus, component proteins identified in this pathway are potential candidates of pharmacological intervention. This review focuses on the characteristics and functions of the molecular targets of the Wnt signaling cascade and how they may be manipulated to achieve anti-tumor effects.

Establishment of crown-root domain borders in mouse incisor

Teeth are composed of two domains, the enamel-covered crown and the enamel-free root. The understanding of the initiation and regulation of crown and root domain formation is important for the development of bioengineered teeth. In most teeth the crown develops before the root, and erupts to the oral cavity whereas the root anchors the tooth to the jawbone. However, in the continuously growing mouse incisor the crown and root domains form simultaneously, the crown domain forming the labial and the root domain the lingual part of the tooth. While the crown-root border on the incisor distal side supports the distal enamel extent, reflecting an evolutionary diet adaptation, on the incisor mesial side the root-like surface is necessary for the attachment of the interdental ligament between the two incisors. Therefore, the mouse incisor exhibits a functional distal-mesial asymmetry. Here, we used the mouse incisor as a model to understand the mechanisms involved in the crown-root border formation. We analyzed the cellular origins and gene expression patterns leading to the development of the mesial and distal crown-root borders. We discovered that Barx2, En1, Wnt11, and Runx3 were exclusively expressed on the mesial crown-root border. In addition, the distal border of the crown-root domain might be established by cells from a different origin and by an early Follistatin expression, factor known to be involved in the root domain formation. The use of different mechanisms to establish domain borders gives indications of the incisor functional asymmetry.

Whole-exome sequencing combined with functional genomics reveals novel candidate driver cancer genes in endometrial cancer

Endometrial cancer is the most common gynecological malignancy, with more than 280,000 cases occurring annually worldwide. Although previous studies have identified important common somatic mutations in endometrial cancer, they have primarily focused on a small set of known cancer genes and have thus provided a limited view of the molecular basis underlying this disease. Here we have developed an integrated systems-biology approach to identifying novel cancer genes contributing to endometrial tumorigenesis. We first performed whole-exome sequencing on 13 endometrial cancers and matched normal samples, systematically identifying somatic alterations with high precision and sensitivity. We then combined bioinformatics prioritization with high-throughput screening (including both shRNA-mediated knockdown and expression of wild-type and mutant constructs) in a highly sensitive cell viability assay. Our results revealed 12 potential driver cancer genes including 10 tumor-suppressor candidates (ARID1A, INHBA, KMO, TTLL5, GRM8, IGFBP3, AKTIP, PHKA2, TRPS1, and WNT11) and two oncogene candidates (ERBB3 and RPS6KC1). The results in the “sensor” cell line were recapitulated by siRNA-mediated knockdown in endometrial cancer cell lines. Focusing on ARID1A, we integrated mutation profiles with functional proteomics in 222 endometrial cancer samples, demonstrating that ARID1A mutations frequently co-occur with mutations in the phosphatidylinositol 3-kinase (PI3K) pathway and are associated with PI3K pathway activation. siRNA knockdown in endometrial cancer cell lines increased AKT phosphorylation supporting ARID1A as a novel regulator of PI3K pathway activity. Our study presents the first unbiased view of somatic coding mutations in endometrial cancer and provides functional evidence for diverse driver genes and mutations in this disease.

Wnt/β-catenin signalling in adrenal physiology and tumour development

Wnt/β-catenin signalling plays essential roles during embryonic development and in adult tissue homeostasis. Canonical signalling through Wnt secreted ligands relies on the control of β-catenin cytoplasmic accumulation and translocation to the nucleus. In this compartment, β-catenin serves as a transcription coactivator for transcription factors such as Lef/Tcf or some nuclear receptors. Constitutive Wnt signalling resulting from inactivation of inhibitors of the pathway or from activating mutations in β-catenin, triggers tumour development in a number of tissues. Analysis of patients' samples and genetically engineered mouse models has shown that Wnt signalling was involved in adrenal development and tumourigenesis. This review will summarise all these recent findings and will focus on some of the mechanisms that may lead to aberrant accumulation of β-catenin in adrenocortical tumours.

Dysregulation of Wnt/β-catenin signaling in gastrointestinal cancers

Aberrant Wnt/β-catenin signaling is widely implicated in numerous malignancies, including cancers of the gastrointestinal tract. Dysregulation of signaling is traditionally attributed to mutations in Axin, adenomatous polyposis coli, and β-catenin that lead to constitutive hyperactivation of the pathway. However, Wnt/β-catenin signaling is also modulated through various other mechanisms in cancer, including cross talk with other altered signaling pathways. A more complex view of Wnt/β-catenin signaling and its role in gastrointestinal cancers is now emerging as divergent phenotypic outcomes are found to be dictated by temporospatial context and relative levels of pathway activation. This review summarizes the dysregulation of Wnt/β-catenin signaling in colorectal carcinoma, hepatocellular carcinoma, and pancreatic ductal adenocarcinoma, with particular emphasis on the latter two. We conclude by addressing some of the major challenges faced in attempting to target the pathway in the clinic.

Wnt11 in 2011 - the regulation and function of a non-canonical Wnt

Genetic studies of Wnt11 have revealed many insights into the roles and regulation of Wnt11, particularly during development. New tools to study Wnt11 have recently become available, making it timely to review the literature regarding this unique Wnt family member. In this study, we focus on mammalian Wnt11, describing its main sites of expression during development, and how the Wnt11 gene is regulated. We highlight an emerging theme in which canonical Wnt signals regulate Wnt11 expression through transcription factors in addition to, or other than, Tcf/LEF family members. We also discuss the frizzled family and other receptors that bind to Wnt11, the intracellular kinases and small GTPases that act downstream of Wnt11, and the effects of Wnt11 on Wnt/β-catenin signalling. Finally, we elaborate on the relevance of Wnt11 to human cancer, where it appears to be important both for proliferation and/or survival during normal differentiation and for migration/invasion.

Immunization with aspartate-β-hydroxylase-loaded dendritic cells produces antitumor effects in a rat model of intrahepatic cholangiocarcinoma

Dendritic cells (DCs) capture and process proteins and present peptides on the cell surface in the context of major histocompatibility complex I and II molecules to induce antigen-specific T cell immune responses. The aims of this study were to (1) employ an expanded and purified DC population and load them with aspartate-β-hydroxylase (ASPH), a highly expressed tumor-associated cell surface protein, and (2) to determine if immunization induced antitumor effects in an orthotopic rat model of intrahepatic cholangiocarcinoma. Splenocytes were incubated with ASPH-coated beads and passed through a magnetic field to yield an 80% pure DC OX62+ population. This DC subset was stimulated with granulocyte-macrophage colony-stimulating factor, interleukin-4, CD40L, and interferon-γ, resulting in a 40-fold increase in interleukin-12A messenger RNA expression to subsequently generate a T helper 1-type immune response. After incubation with the cytokine cocktail, DCs were found to have matured, as demonstrated by increased expression of CD40, CD80, and CD86 costimulatory molecules. Immunization with ASPH-loaded DCs induced antigen-specific immunity. A clone of the parental tumorigenic rat BDEneu cholangiocyte cell line, designated BDEneu-CL24, was found to have the highest number of cells expressing this surface protein (97%); it maintained the same phenotypic characteristics of the parental cell line and was used to produce intrahepatic tumors in immunocompetent syngeneic Fisher-344 rats. Immunization with ASPH-loaded DCs generated cytotoxicity against cholangiocarcinoma cells in vitro and significantly suppressed intrahepatic tumor growth and metastasis, and was associated with increased CD3+ lymphocyte infiltration into the tumors.

CONCLUSION

These findings suggest that immunization with ASPH-loaded DCs may constitute a novel therapeutic approach for intrahepatic cholangiocarcinoma, because this protein also appears to be highly conserved and expressed on human hepatobiliary tumors.

Possible involvement of Wnt11 in colorectal cancer progression

Our previous report revealed that the expression of Frizzled-7 (FZD7) in colorectal cancer (CRC) and its possible role in CRC progression. In this study we measured the expression levels of candidate FZD7 ligands, Wnt3 and Wnt11 in colon cancer cell lines (n = 7) and primary CRC tissues (n = 133) by quantitative RT-PCR. We also examined the functional effects of Wnt11 with the use of Wnt11 transfectants of colon cancer HCT-116 cells. Wnt11 transfectants showed the increased proliferation and migration/invasion activities compared to mock cells. Western blot analysis of transfectants revealed that phosphorylation of JNK and c-jun was increased after Wnt11 transfection. Wnt11 mRNA expression was significantly higher in the stage I, II, III, or IV tumor tissues than in non-tumor tissues (overall P < 0.003), while there was no significant difference in Wnt3 mRNA expression between tumor and non-tumor tissues. In addition, Wnt11 mRNA expression was significantly higher in patients with recurrence or death after surgery than in those with no recurrence (disease free) after surgery (P = 0.018). We also compared the expression levels of Wnt11 mRNA with those of FZD7 mRNA in the same CRC samples. Wnt11 mRNA expression was significantly higher in patients with higher FZD7 mRNA levels than in those with lower FZD7 mRNA levels (P = 0.0005). The expression levels of Wnt11 mRNA were correlated with those of FZD7 mRNA (P < 0.0001). These data suggest that Wnt11 may play an important role in CRC progression.

Planar polarity: A new player in both lung development and disease

The clinical burden of both adult and neonatal lung disease worldwide is substantial; in the UK alone, respiratory disease kills one in four people. It is increasingly recognized that genes and pathways that regulate lung development, may be aberrantly activated in disease and/or reactivated as part of the lungs' intrinsic repair mechanisms. Investigating the genes and signaling pathways that regulate lung growth has led to significant insights into the pathogenesis of congenital and adult lung disease. Recently, the planar cell polarity (PCP) pathway has been shown to be required for normal lung development, and data suggests that this signaling pathway is also involved in the pathogenesis of some lung diseases. In this review, we summarize current evidence indicating that the PCP pathway is required for both lung development and disease.