Nr-CAM is a target gene of the beta-catenin/LEF-1 pathway in melanoma and colon cancer and its expression enhances motility and confers tumorigenesis

Identification of glutamine metabolism-related gene signature to predict colorectal cancer prognosis

Backgrounds: Colorectal cancer (CRC) is a highly malignant gastrointestinal malignancy with a poor prognosis, which imposes a significant burden on patients and healthcare providers globally. Previous studies have established that genes related to glutamine metabolism play a crucial role in the development of CRC. However, no studies have yet explored the prognostic significance of these genes in CRC. Methods: CRC patient data were downloaded from The Cancer Genome Atlas (TCGA), while glutamine metabolism-related genes were obtained from the Molecular Signatures Database (MSigDB) database. Univariate COX regression analysis and LASSO Cox regression were utilized to identify 15 glutamine metabolism-related genes associated with CRC prognosis. The risk scores were calculated and stratified into high-risk and low-risk groups based on the median risk score. The model's efficacy was assessed using Kaplan-Meier survival analysis and receiver operating characteristic (ROC) curve analysis. Cox regression analysis was employed to determine the risk score as an independent prognostic factor for CRC. Differential immune cell infiltration between the high-risk and low-risk groups was assessed using the ssGSEA method. The clinical applicability of the model was validated by constructing nomograms based on age, gender, clinical staging, and risk scores. Immunohistochemistry (IHC) was used to detect the expression levels of core genes. Results: We identified 15 genes related to glutamine metabolism in CRC: NLGN1, RIMKLB, UCN, CALB1, SYT4, WNT3A, NRCAM, LRFN4, PHGDH, GRM1, CBLN1, NRG1, GLYATL1, CBLN2, and VWC2. Compared to the high-risk group, the low-risk group demonstrated longer overall survival (OS) for CRC. Clinical correlation analysis revealed a positive correlation between the risk score and the clinical stage and TNM stage of CRC. Immune correlation analysis indicated a predominance of Th2 cells in the low-risk group. The nomogram exhibited excellent discriminatory ability for OS in CRC. Immunohistochemistry revealed that the core gene CBLN1 was expressed at a lower level in CRC, while GLYATL1 was expressed at a higher level. Conclusions: In summary, we have successfully identified and comprehensively analyzed a gene signature associated with glutamine metabolism in CRC for the first time. This gene signature consistently and reliably predicts the prognosis of CRC patients, indicating its potential as a metabolic target for individuals with CRC.

Perineural invasion in colorectal cancer: mechanisms of action and clinical relevance

BACKGROUND

In recent years, the significance of the nervous system in the tumor microenvironment has gained increasing attention. The bidirectional communication between nerves and cancer cells plays a critical role in tumor initiation and progression. Perineural invasion (PNI) occurs when tumor cells invade the nerve sheath and/or encircle more than 33% of the nerve circumference. PNI is a common feature in various malignancies and is associated with tumor invasion, metastasis, cancer-related pain, and unfavorable clinical outcomes. The colon and rectum are highly innervated organs, and accumulating studies support PNI as a histopathologic feature of colorectal cancer (CRC). Therefore, it is essential to investigate the role of nerves in CRC and comprehend the mechanisms of PNI to impede tumor progression and improve patient survival.

CONCLUSION

This review elucidates the clinical significance of PNI, summarizes the underlying cellular and molecular mechanisms, introduces various experimental models suitable for studying PNI, and discusses the therapeutic potential of targeting this phenomenon. By delving into the intricate interactions between nerves and tumor cells, we hope this review can provide valuable insights for the future development of CRC treatments.

Liver cancer stem cell dissemination and metastasis: uncovering the role of NRCAM in hepatocellular carcinoma

BACKGROUND

Liver cancer stem cells (LCSCs) play an important role in hepatocellular carcinoma (HCC), but the mechanisms that link LCSCs to HCC metastasis remain largely unknown. This study aims to reveal the contributions of NRCAM to LCSC function and HCC metastasis, and further explore its mechanism in detail.

METHODS

117 HCC and 29 non-HCC patients with focal liver lesions were collected and analyzed to assess the association between NRCAM and HCC metastasis. Single-cell RNA sequencing (scRNA-seq) was used to explore the biological characteristics of cells with high NRCAM expression in metastatic HCC. The role and mechanism of NRCAM in LCSC dissemination and metastasis was explored in vitro and in vivo using MYC-driven LCSC organoids from murine liver cells.

RESULTS

Serum NRCAM is associated with HCC metastasis and poor prognosis. A scRNA-seq analysis identified that NRCAM was highly expressed in LCSCs with MYC activation in metastatic HCC. Moreover, NRCAM facilitated LCSC migration and invasion, which was confirmed in MYC-driven LCSC organoids. The in vivo tumor allografts demonstrated that NRCAM mediated intra-hepatic/lung HCC metastasis by enhancing the ability of LCSCs to escape from tumors into the bloodstream. Nrcam expression inhibition in LCSCs blocked HCC metastasis. Mechanistically, NRCAM activated epithelial-mesenchymal transition (EMT) and metastasis-related matrix metalloproteinases (MMPs) through the MACF1 mediated β-catenin signaling pathway in LCSCs.

CONCLUSIONS

LCSCs typified by high NRCAM expression have a strong ability to invade and migrate, which is an important factor leading to HCC metastasis.

Knockdown of LINC00702 inhibits the growth and induces apoptosis of breast cancer through the Wnt/β-catenin pathway

Long non-coding RNAs (lncRNAs) are essential in many biological areas like cell growth and apoptosis. The role of recently discovered LINC00702 is yet to be explored. Therefore, we wanted to elucidate its role in breast cancer (BC) with bioinformatic and various methods. LINC00702 expression was predicted using bioinformatic analysis and confirmed by RT-qPCR. Furthermore, the impact of LINC00702 knockdown on BC progression was evaluated. High LINC00702 level could lead to a worse outcome in BC patients. Additionally, CCK-8, EdU,and Annexin V-APC7/AAD experiments showed that LINC00702 knockdown inhibited the growth of BT-474 and T-47D cells and promoted their apoptosis. Moreover, in vivo experiments showed that shLINC00702-2 significantly reduced tumor sizes and suppressed c-Myc and β-catenin expressions. On the contrary, a rescue assay showed that HLY78, an activator of the Wnt/β-catenin pathway, reversed the cell-inhibiting impact of LINC00702 knockdown. LINC00702 is an oncogenic lncRNA that promotes BC progression by stimulating the Wnt/β-catenin pathway and downstream proteins, making it a promising target for further research on BC treatment.

Dosimetry of a Novel 111Indium-Labeled Anti-P-Cadherin Monoclonal Antibody (FF-21101) in Non-Human Primates

P-cadherin is associated with a wide range of tumor types, making it an attractive therapeutic target. FF-21101 is a human-mouse chimeric monoclonal antibody (mAb) directed against human P-cadherin, which has been radioconjugated with indium-111 (111In) utilizing a DOTA chelator. We investigated the biodistribution of FF-21101(111In) in cynomolgus macaques and extrapolated the results to estimate internal radiation doses of 111In- and yttrium-90 (90Y)-FF-21101 for targeted radioimmunotherapy in humans. Whole-body planar and SPECT imaging were performed at 0, 2, 24, 48, 72, 96, and 120 h post-injection, using a dual-head gamma camera. Volumes of interest of identifiable source organs of radioactivity were defined on aligned reference CT and serial SPECT images. Organs with the highest estimated dose values (mSv/MBq) for FF-21101(111In) were the lungs (0.840), spleen (0.816), liver (0.751), kidneys (0.629), and heart wall (0.451); and for FF-21101(90Y) dose values were: lungs (10.49), spleen (8.21), kidneys (5.92), liver (5.46), and heart wall (2.61). FF-21101(111In) exhibits favorable biodistribution in cynomolgus macaques and estimated human dosimetric characteristics. Data obtained in this study were used to support the filing of an investigational new drug application with the FDA for a Phase I clinical trial.

An Increase in Mucin2 Expression Is Required for Colon Cancer Progression Mediated by L1

An induction in the expression of the cell adhesion receptor L1, a Wnt target gene, is a characteristic feature of Wnt/β-catenin activation in colon cancer cells at later stages of the disease. We investigated the proteins secreted following L1 expression in colon cancer cells and identified Mucin2 among the most abundant secreted proteins. We found that suppressing Mucin2 expression in L1-expressing colon cancer cells inhibits cell proliferation, motility, tumorigenesis, and liver metastasis. We detected several signaling pathways involved in Mucin2 induction in L1-expressing cells. In human colon cancer tissue, Mucin2 expression was significantly reduced or lost in the adenocarcinoma tissue, while in the mucinous subtype of colon cancer tissue, Mucin2 expression was increased. An increased signature of L1/Mucin2 expression reduced the survival rate of human colon cancer patients. Thus, induction of Mucin2 expression by L1 is required during mucinous colon cancer progression and can serve as a marker for diagnosis and a target for therapy.

GMMchi: gene expression clustering using Gaussian mixture modeling

BACKGROUND

Cancer evolution consists of a stepwise acquisition of genetic and epigenetic changes, which alter the gene expression profiles of cells in a particular tissue and result in phenotypic alterations acted upon by natural selection. The recurrent appearance of specific genetic lesions across individual cancers and cancer types suggests the existence of certain "driver mutations," which likely make up the major contribution to tumors' selective advantages over surrounding normal tissue and as such are responsible for the most consequential aspects of the cancer cells' gene expression patterns and phenotypes. We hypothesize that such mutations are likely to cluster with specific dichotomous shifts in the expression of the genes they most closely control, and propose GMMchi, a Python package that leverages Gaussian Mixture Modeling to detect and characterize bimodal gene expression patterns across cancer samples, as a tool to analyze such correlations using 2 × 2 contingency table statistics.

RESULTS

Using well-defined simulated data, we were able to confirm the robust performance of GMMchi, reaching 85% accuracy with a sample size of n = 90. We were also able to demonstrate a few examples of the application of GMMchi with respect to its capacity to characterize background florescent signals in microarray data, filter out uninformative background probe sets, as well as uncover novel genetic interrelationships and tumor characteristics. Our approach to analysing gene expression analysis in cancers provides an additional lens to supplement traditional continuous-valued statistical analysis by maximizing the information that can be gathered from bulk gene expression data.

CONCLUSIONS

We confirm that GMMchi robustly and reliably extracts bimodal patterns from both colorectal cancer (CRC) cell line-derived microarray and tumor-derived RNA-Seq data and verify previously reported gene expression correlates of some well-characterized CRC phenotypes.

AVAILABILITY

The Python package GMMchi and our cell line microarray data used in this paper is available for downloading on GitHub at https://github.com/jeffliu6068/GMMchi .

NrCAM secreted by endometrial stromal cells enhances the progestin sensitivity of endometrial cancer cells through epigenetic modulation of PRB

Progestin is one of the main hormone treatment regimens for early-stage estrogen receptor- and progesterone receptor (PR)-positive endometrial cancer (EC). However, the response rate of EC to progestins is unsatisfactory. Investigating the mechanisms related to progestin treatment could help improve treatment efficacy. Studies have demonstrated that normal endometrial stromal cells (ESCs) increase the inhibitory effect of progestin on EC cell proliferation via paracrine signaling, but the mechanisms involved remain unclear. In this study, we found that ESCs had different morphological features between progestin-sensitive and -insensitive EC tissues. ESCs presented typical decidualization changes in progestin-sensitive cases, while they remained slim in progestin-insensitive EC lesions, indicating no response. Furthermore, ESCs enhanced the inhibitory effect of medroxyprogesterone acetate (MPA) on EC cell proliferation by secreting neuron cell adhesion molecule (NrCAM). MPA treatment enhanced NrCAM secretion by ESCs. EC xenografts in BALB/C nude mice demonstrated that MPA combined with NrCAM had an increased tumor inhibitory effect compared with MPA or NrCAM alone. Mechanistically, MPA upregulated NrCAM expression in ESCs through PR. Specifically, NrCAM increased PR expression in EC cells through TET1-induced hydroxymethylation of the PRB gene promoter region. These findings indicate that NrCAM or NrCAM combined with progestins could be a new EC treatment.

Role of Cell-Cell Junctions in Oesophageal Squamous Cell Carcinoma

Cell-cell junctions comprise various structures, including adherens junctions, tight junctions, desmosomes, and gap junctions. They link cells to each other in tissues and regulate tissue homeostasis in critical cellular processes. Recent advances in cell-cell junction research have led to critical discoveries. Cell-cell adhesion components are important for the invasion and metastasis of tumour cells, which are not only related to cell-cell adhesion changes, but they are also involved in critical molecular signal pathways. They are of great significance, especially given that relevant molecular mechanisms are being discovered, there are an increasing number of emerging biomarkers, targeted therapies are becoming a future therapeutic concern, and there is an increased number of therapeutic agents undergoing clinical trials. Oesophageal squamous cell carcinoma (ESCC), the most common histological subtype of oesophageal cancer, is one of the most common cancers to affect epithelial tissue. ESCC progression is accompanied by the abnormal expression or localisation of components at cell-cell junctions. This review will discuss the recent scientific developments related to the molecules at cell-cell junctions and their role in ESCC to offer valuable insights for readers, provide a global view of the relationships between position, construction, and function, and give a reference for future mechanistic studies, diagnoses, and therapeutic developments.

Downregulation of the Tumor Suppressor TFF1 Is Required during Induction of Colon Cancer Progression by L1

Simple Summary

Aberrant activation of Wnt/β-catenin signaling and the subsequent induction of downstream target genes is a hallmark of colorectal cancer (CRC) development. Previously, we found that overexpression of the immunoglobulin-like cell adhesion receptor L1CAM (L1), a target of the Wnt/β-catenin pathway, confers enhanced proliferation, motility, tumorigenesis, and liver metastasis in CRC cells. Transcriptomic and proteomic analyses revealed changes in both pro-tumorigenic and potential tumor-suppressor genes in L1-overexpressing CRC cells. We wished to identify such tumor suppressor/s, and found that trefoil family factor 1 (TFF1) was involved in L1-mediated CRC progression. TFF1 overexpression suppressed the growth, motility and tumorigenesis of L1-expressing CRC cells by inhibiting the NF-κB pathway. In human CRC tissue, TFF1-positive staining was evident in goblet cells of the normal mucosa, while in CRC tissue, TFF1 expression was lost in >50% of the tumor samples. Our results support a tumor-suppressor role of TFF1 in human CRC, and we suggest that TFF1 could be used for CRC detection and as a novel therapeutic target in L1-mediated CRC.

Abstract

The immunoglobulin family cell adhesion receptor L1 is induced in CRC cells at the invasive front of the tumor tissue, and confers enhanced proliferation, motility, tumorigenesis, and liver metastasis. To identify putative tumor suppressors whose expression is downregulated in L1-expressing CRC cells, we blocked the L1–ezrin–NF-κB signaling pathway and searched for genes induced under these conditions. We found that TFF1, a protein involved in protecting the mucus epithelial layer of the colon, is downregulated in L1-expressing cells and displays characteristics of a tumor suppressor. Overexpression of TFF1 in L1-transfected human CRC cells blocks the pro-tumorigenic and metastatic properties conferred by L1 by suppressing NF-κB signaling. Immunohistochemical analyses revealed that human CRC tissue samples often lose the expression of TFF1, while the normal mucosa displays TFF1 in goblet cells. Identifying TFF1 as a tumor suppressor in CRC cells could provide a novel marker for L1-mediated CRC development and a potential target for therapy.

KLF9 regulates miR-338-3p/NRCAM axis to block the progression of osteosarcoma cells

Background: MiR-338-3p is revealed to serve as a tumor suppressor in several carcinomas. Whereas, the effect of miR-338-3p in the progression of osteosarcoma has not been explored. The aim of this paper was to analyze the functional influences of miR-338-3p on osteosarcoma progression and the potential mechanism.

Methods: The expression of genes and miRNAs in osteosarcoma cells was assessed via western blotting or quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Osteosarcoma cellular proliferation was explored by MTT and EdU incorporation assay. Osteosarcoma cellular migratory and invasive capacity was explored by wound-healing and transwell assay. Bioinformatics approaches were adopted to predict target genes. The relationships between miR-338-3p and neuron‑glial‑related cell adhesion (NRCAM), between kruppel-like factor 9 (KLF9) and miR-338-3p were verified by dual-luciferase reporter assay.

Results: We found that miR-338-3p was reduced in osteosarcoma and that higher expression of miR-338-3p suppressed proliferative, invasive and migratory ability of osteosarcoma cells. Furthermore, the result showed that overexpression of NRCAM could reduce the anti-tumor role of miR-338-3p in osteosarcoma cells. In addition, we found that overexpression of KLF9 could enhance the expression level of miR-338-3p in osteosarcoma cells.

Conclusion: The KLF9/miR-338-3p/NRCAM axis played a significant role in regulating osteosarcoma progression, which may become a promising therapeutic method for osteosarcoma.

Loss of Function of the Neural Cell Adhesion Molecule NrCAM Regulates Differentiation, Proliferation and Neurogenesis in Early Postnatal Hypothalamic Tanycytes

Hypothalamic tanycytes are neural stem and progenitor cells, but little is known of how they are regulated. Here we provide evidence that the cell adhesion molecule, NrCAM, regulates tanycytes in the adult niche. NrCAM is strongly expressed in adult mouse tanycytes. Immunohistochemical and in situ hybridization analysis revealed that NrCAM loss of function leads to both a reduced number of tanycytes and reduced expression of tanycyte-specific cell markers, along with a small reduction in tyrosine hydroxylase-positive arcuate neurons. Similar analyses of NrCAM mutants at E16 identify few changes in gene expression or cell composition, indicating that NrCAM regulates tanycytes, rather than early embryonic hypothalamic development. Neurosphere and organotypic assays support the idea that NrCAM governs cellular homeostasis. Single-cell RNA sequencing (scRNA-Seq) shows that tanycyte-specific genes, including a number that are implicated in thyroid hormone metabolism, show reduced expression in the mutant mouse. However, the mild tanycyte depletion and loss of markers observed in NrCAM-deficient mice were associated with only a subtle metabolic phenotype.

Tankyrase Regulates Neurite Outgrowth through Poly(ADP-ribosyl)ation-Dependent Activation of β-Catenin Signaling

Poly(ADP-ribosyl)ation is a post-translational modification of proteins by transferring poly(ADP-ribose) (PAR) to acceptor proteins by the action of poly(ADP-ribose) polymerase (PARP). Two tankyrase (TNKS) isoforms, TNK1 and TNK2 (TNKS1/2), are ubiquitously expressed in mammalian cells and participate in diverse cellular functions, including wnt/β-catenin signaling, telomere maintenance, glucose metabolism and mitosis regulation. For wnt/β-catenin signaling, TNKS1/2 catalyze poly(ADP-ribosyl)ation of Axin, a key component of the β-catenin degradation complex, which allows Axin’s ubiquitination and subsequent degradation, thereby activating β-catenin signaling. In the present study, we focused on the functions of TNKS1/2 in neuronal development. In primary hippocampal neurons, TNKS1/2 were detected in the soma and neurites, where they co-localized with PAR signals. Treatment with XAV939, a selective TNKS1/2 inhibitor, suppressed neurite outgrowth and synapse formation. In addition, XAV939 also suppressed norepinephrine uptake in PC12 cells, a rat pheochromocytoma cell line. These effects likely resulted from the inhibition of β-catenin signaling through the stabilization of Axin, which suggests TNKS1/2 enhance Axin degradation by modifying its poly(ADP-ribosyl)ation, thereby stabilizing wnt/β-catenin signaling and, in turn, promoting neurite outgrowth and synapse formation.

A Necessary Role for Increased Biglycan Expression during L1-Mediated Colon Cancer Progression

Aberrant activation of Wnt/β-catenin signaling and downstream β-catenin-TCF target genes is a hallmark of colorectal cancer (CRC) development. We identified the immunoglobulin-like cell adhesion receptor L1CAM (L1) as a target of β-catenin-TCF transactivation in CRC cells. Overexpression of L1 in CRC cells confers enhanced proliferation, motility, tumorigenesis, and liver metastasis, and L1 is exclusively localized at invasive areas of human CRC tissue. Several genes are induced after L1 transfection into CRC cells by a mechanism involving the L1-ezrin-NF-κB pathway. We conducted a secretomic analysis of the proteins in the culture medium of L1-overexpressing CRC cells. We detected a highly increased level of biglycan, a small leucine-rich ECM component, and a signaling molecule. We found that induction of biglycan is required for the cellular processes conferred by L1, including enhanced proliferation, motility, tumorigenesis, and liver metastasis. The suppression of endogenous biglycan levels or a point mutation in the L1 ectodomain that regulates cell–cell adhesion mediated by L1 blocked the enhanced tumorigenic properties conferred by L1. The mechanism of biglycan induction by L1 involves the L1-NF-κB pathway. Blocking NF-κB signaling in L1 expressing cells suppressed the induction of biglycan and the tumorigenic properties conferred by L1. Biglycan expression was undetectable in the normal colonic mucosa, but expressed at highly increased levels in the tumor tissue, especially in the stroma. The therapeutic strategies to target biglycan expression might provide a useful approach for CRC treatment in L1-overexpressing tumors.

Flashlight into the Function of Unannotated C11orf52 using Affinity Purification Mass Spectrometry

For an enhanced understanding of the biological mechanisms of human disease, it is essential to investigate protein functions. In a previous study, we developed a prediction method of gene ontology (GO) terms by the I-TASSER/COFACTOR result, and we applied this to uPE1 in chromosome 11. Here, to validate the bioinformatics prediction of C11orf52, we utilized affinity purification and mass spectrometry to identify interacting partners of C11orf52. Using immunoprecipitation methods with three different peptide tags (Myc, Flag, and 2B8) in HEK 293T cell lines, we identified 79 candidate proteins that are expected to interact with C11orf52. The results of a pathway analysis of the GO and STRING database with candidate proteins showed that C11orf52 could be related to signaling receptor binding, cell-cell adhesion, and ribosome biogenesis. Then, we selected three partner candidates of DSG1, JUP, and PTPN11 for verification of the interaction with C11orf52 and confirmed them by colocalization at the cell-cell junctions by coimmunofluorescence experiments. On the basis of this study, we expect that C11orf52 is related to the Wnt signaling pathway via DSG1 from the protein-protein interactions, given the results of a comprehensive analysis of the bioinformatic predictions. The data set is available at the ProteomeXchange consortium via PRIDE repository (PXD026986).

NOTUM promotes thermogenic capacity and protects against diet-induced obesity in male mice

We recently showed that NOTUM, a liver-secreted Wnt inhibitor, can acutely promote browning of white adipose. We now report studies of chronic overexpression of NOTUM in liver indicating that it protects against diet-induced obesity and improves glucose homeostasis in mice. Adeno-associated virus (AAV) vectors were used to overexpress GFP or mouse Notum in the livers of male C57BL/6J mice and the mice were fed an obesifying diet. After 14 weeks of high fat, high sucrose diet feeding, the AAV-Notum mice exhibited decreased obesity and improved glucose tolerance compared to the AAV-GFP mice. Gene expression and immunoblotting analysis of the inguinal fat and brown fat revealed increased expression of beige/brown adipocyte markers in the AAV-Notum group, suggesting enhanced thermogenic capacity by NOTUM. A β3 adrenergic receptor agonist-stimulated lipolysis test suggested increased lipolysis capacity by NOTUM. The levels of collagen and C–C motif chemokine ligand 2 (CCL2) in the epididymal white adipose tissue of the AAV-Notum mice were significantly reduced, suggesting decreased fibrosis and inflammation, respectively. RNA sequencing analysis of inguinal white adipose of 4-week chow diet-fed mice revealed a highly significant enrichment of extracellular matrix (ECM) functional cluster among the down-regulated genes in the AAV-Notum group, suggesting a potential mechanism contributing to improved glucose homeostasis. Our in vitro studies demonstrated that recombinant human NOTUM protein blocked the inhibitory effects of WNT3A on brown adipocyte differentiation. Furthermore, NOTUM attenuated WNT3A’s effects on upregulation of TGF-β signaling and its downstream targets. Overall, our data suggest that NOTUM modulates adipose tissue function by promoting thermogenic capacity and inhibiting fibrosis through inhibition of Wnt signaling.

The Collagen-Modifying Enzyme PLOD2 Is Induced and Required during L1-Mediated Colon Cancer Progression

The overactivation of Wnt/β-catenin signaling is a hallmark of colorectal cancer (CRC) development. We identified the cell adhesion molecule L1CAM (L1) as a target of β-catenin-TCF transactivation in CRC cells. The overexpression of L1 in CRC cells confers enhanced proliferation, motility, tumorigenesis and liver metastasis, and L1 is exclusively localized in the invasive areas of human CRC tissue. A number of genes are induced after L1 transfection into CRC cells by a mechanism involving the cytoskeletal protein ezrin and the NF-κB pathway. When studying the changes in gene expression in CRC cells overexpressing L1 in which ezrin levels were suppressed by shRNA to ezrin, we discovered the collagen-modifying enzyme lysyl hydroxylase 2 (PLOD2) among these genes. We found that increased PLOD2 expression was required for the cellular processes conferred by L1, including enhanced proliferation, motility, tumorigenesis and liver metastasis, since the suppression of endogenous PLOD2 expression, or its enzymatic activity, blocked the enhanced tumorigenic properties conferred by L1. The mechanism involved in increased PLOD2 expression by L1 involves ezrin signaling and PLOD2 that affect the SMAD2/3 pathway. We found that PLOD2 is localized in the colonic crypts in the stem cell compartment of the normal mucosa and is found at increased levels in invasive areas of the tumor and, in some cases, throughout the tumor tissue. The therapeutic strategies to target PLOD2 expression might provide a useful approach for CRC treatment.

lncRNA:mRNA expression profile in CD4+ T cells from patients with Graves' disease

Graves' disease (GD) is a common autoimmune disease that affects the thyroid gland. As a new class of modulators of gene expression, long noncoding RNAs (lncRNAs) have been reported to play a vital role in immune functions and in the development of autoimmunity and autoimmune disease. The aim of this study is to identify lncRNAs in CD4+ T cells as potential biomarkers of GD. lncRNA and mRNA microarrays were performed to identify differentially expressed lncRNAs and mRNAs in GD CD4+ T cells compared with healthy control CD4+ T cells. Quantitative PCR (qPCR) was used to validate the results, and correlation analysis was used to analyze the relationship between these aberrantly expressed lncRNAs and clinical parameters. The microarray identified 164 lncRNAs and 93 mRNAs in GD CD4+ T cells differentially expressed compared to healthy control CD4+ T cells (fold change >2.0 and a P < 0.05). Further analysis consistently showed that the expression of HMlincRNA1474 (P < 0.01) and TCONS_00012608 (P < 0.01) was suppressed, while the expression of AK021954 (P < 0.01) and AB075506 (P < 0.01) was upregulated from initial GD patients. In addition, their expression levels were recovered in euthyroid GD patients and GD patients in remission. Moreover, these four aberrantly expressed lncRNAs were correlated with GD clinical parameters. Moreover, the areas under the ROC curve were 0.8046, 0.7579, 0.8115 for AK021954, AB075506, HMlincRNA1474, respectively. The present work revealed that differentially expressed lncRNAs were associated with GD, which might serve as novel biomarkers of GD and potential targets for GD treatment.

The Inhibitory Role of miR-486-5p on CSC Phenotype Has Diagnostic and Prognostic Potential in Colorectal Cancer

Colorectal cancer (CRC) is the third most frequent cancer worldwide and the second cause of cancer deaths. Increasing evidences supports the idea that the poor prognosis of patients is related to the presence of cancer stem cells (CSCs), a cell population able to drive cancer recurrence and metastasis. The deregulation of microRNAs (miRNAs) plays a role in the formation of CSC. We investigated the role of hsa-miR-486-5p (miR-486-5p) in CRC, CSCs, and metastasis, in order to reach a better understanding of the biomolecular and epigenetic mechanisms mir-486-5p-related. The expression of miR-486-5p was investigated in three different matrices from CRC patients and controls and in CSCs obtained from the CRC cell lines HCT-116, HT-29, and T-84. In the human study, miR-486-5p was up-regulated in serum and stool of CRC patients in comparison with healthy controls but down-regulated in tumor tissue when compared with normal mucosa. miR-486-5p was also down-regulated in the sera of metastatic patients. In vitro, miR-486-5p was down-regulated in CSC models and it induced an inhibitory effect on stem factors and oncogenes in the main pathways of CSCs. Our results provide a step forward in understanding the role of mir-486-5p in CRC and CSC, and suggest that further studies are needed to investigate its diagnostic and prognostic power, possibly in combination with other biomarkers.

Wnt/β-Catenin Target Genes in Colon Cancer Metastasis: The Special Case of L1CAM

Simple Summary

The Wnt/β-catenin cell–cell signaling pathway is one of the most basic and highly conserved pathways for intercellular communications regulating key steps during development, differentiation, and cancer. In colorectal cancer (CRC), in particular, aberrant activation of the Wnt/β-catenin pathway is believed to be responsible for perpetuating the disease from the very early stages of cancer development. A large number of downstream target genes of β-catenin-T-cell factor (TCF), including oncogenes, were detected as regulators of CRC development. In this review, we will summarize studies mainly on one such target gene, the L1CAM (L1) cell adhesion receptor, that is selectively induced in invasive and metastatic CRC cells and in regenerating cells of the intestine following injury. We will describe studies on the genes activated when the levels of L1 are increased in CRC cells and their effectiveness in propagating CRC development. These downstream targets of L1-signaling can serve in diagnosis and may provide additional targets for CRC therapy.

Abstract

Cell adhesion to neighboring cells is a fundamental biological process in multicellular organisms that is required for tissue morphogenesis. A tight coordination between cell–cell adhesion, signaling, and gene expression is a characteristic feature of normal tissues. Changes, and often disruption of this coordination, are common during invasive and metastatic cancer development. The Wnt/β-catenin signaling pathway is an excellent model for studying the role of adhesion-mediated signaling in colorectal cancer (CRC) invasion and metastasis, because β-catenin has a dual role in the cell; it is a major adhesion linker of cadherin transmembrane receptors to the cytoskeleton and, in addition, it is also a key transducer of Wnt signaling to the nucleus, where it acts as a co-transcriptional activator of Wnt target genes. Hyperactivation of Wnt/β-catenin signaling is a common feature in the majority of CRC patients. We found that the neural cell adhesion receptor L1CAM (L1) is a target gene of β-catenin signaling and is induced in carcinoma cells of CRC patients, where it plays an important role in CRC metastasis. In this review, we will discuss studies on β-catenin target genes activated during CRC development (in particular, L1), the signaling pathways affected by L1, and the role of downstream target genes activated by L1 overexpression, especially those that are also part of the intestinal stem cell gene signature. As intestinal stem cells are highly regulated by Wnt signaling and are believed to also play major roles in CRC progression, unravelling the mechanisms underlying the regulation of these genes will shed light on both normal intestinal homeostasis and the development of invasive and metastatic CRC.

Different Shades of L1CAM in the Pathophysiology of Cancer Stem Cells

L1 cell adhesion molecule (L1CAM) is aberrantly expressed in several tumor types where it is causally linked to malignancy and therapy resistance, acting also as a poor prognosis factor. Accordingly, several approaches have been developed to interfere with L1CAM function or to deliver cytotoxic agents to L1CAM-expressing tumors. Metastatic dissemination, tumor relapse and drug resistance can be fueled by a subpopulation of neoplastic cells endowed with peculiar biological properties that include self-renewal, efficient DNA repair, drug efflux machineries, quiescence, and immune evasion. These cells, known as cancer stem cells (CSC) or tumor-initiating cells, represent, therefore, an ideal target for tumor eradication. However, the molecular and functional traits of CSC have been unveiled only to a limited extent. In this context, it appears that L1CAM is expressed in the CSC compartment of certain tumors, where it plays a causal role in stemness itself and/or in biological processes intimately associated with CSC (e.g., epithelial-mesenchymal transition (EMT) and chemoresistance). This review summarizes the role of L1CAM in cancer focusing on its functional contribution to CSC pathophysiology. We also discuss the clinical usefulness of therapeutic strategies aimed at targeting L1CAM in the context of anti-CSC treatments.

Relationship between apical junction proteins, gene expression and cancer

The apical junctional complex (AJC) is a cell-cell adhesion system present at the upper portion of the lateral membrane of epithelial cells integrated by the tight junction (TJ) and the adherens junction (AJ). This complex is crucial to initiate and stabilize cell-cell adhesion, to regulate the paracellular transit of ions and molecules and to maintain cell polarity. Moreover, we now consider the AJC as a hub of signal transduction that regulates cell-cell adhesion, gene transcription and cell proliferation and differentiation. The molecular components of the AJC are multiple and diverse and depending on the cellular context some of the proteins in this complex act as tumor suppressors or as promoters of cell transformation, migration and metastasis outgrowth. Here, we describe these new roles played by TJ and AJ proteins and their potential use in cancer diagnostics and as targets for therapeutic intervention.

ISG15 induction is required during L1-mediated colon cancer progression and metastasis

Hyperactivation of Wnt/β-catenin target gene expression is a hallmark of colorectal cancer (CRC) development. We identified L1-CAM (L1) and Nr-CAM, members of the immunoglobulin family of nerve cell adhesion receptors, as target genes of the Wnt/β-catenin pathway in CRC cells. L1 overexpression in CRC cells enhances their motile and tumorigenic capacity and promotes liver metastasis. L1 is often localized at the invasive edge of CRC tissue. Using gene arrays and proteomic analyses we identified downstream signaling pathways and targets of L1-mediated signaling. Here, we found that the expression of interferon-stimulated gene 15 (ISG15) that operates much like ubiquitin (is conjugated to proteins by ISGylation), is elevated in the conditioned medium and in CRC cells overexpressing L1. Suppression of endogenous ISG15 levels in L1-expressing cells blocked the increased proliferative, motile, tumorigenic and liver metastatic capacities of CRC cells. ISG15 overexpression, on its own, could enhance these properties in CRC cells, but only to a much lower extent compared to L1. We show that NF-κB signaling is involved in the L1-mediated increase in ISG15, since blocking the NF-κB pathway abolished the induction of ISG15 by L1. Point mutations in the L1 ectodomain that interfere with its binding to L1 ligands, also inhibited the increase in ISG15. We detected high levels of ISG15 in human CRC tissue cells and in the adjacent stroma, but not in the normal mucosa. The results suggest that ISG15 is involved in L1-mediated CRC development and is a potential target for CRC therapy.

Increased expression of cathepsin D is required for L1-mediated colon cancer progression

Hyperactivation of Wnt/β-catenin target genes is considered a key step in human colorectal cancer (CRC) development. We previously identified the immunoglobulin-like cell adhesion receptor L1 as a target gene of β-catenin/TCF transactivation that is localized at the invasive edge of CRC tissue. Using gene arrays, we discovered a number of downstream target genes and signaling pathways conferred by L1 overexpression during colon cancer progression. Here, we have used a proteomic approach to identify proteins in the secretome of L1-overexpressing CRC cells and studied the role of the increase in the aspartate protease cathepsin D (CTSD) in L1-mediated colon cancer development. We found that in addition to the increase in CTSD in the secretome, the RNA and protein levels of CTSD were also induced by L1 in CRC cells. CTSD overexpression resulted in elevated proliferation under stress and increased motility, tumorigenesis and liver metastasis, although to a lesser extent than after L1-transfection. The suppression of endogenous CTSD in L1-expressing cells blocked the increase in the proliferative, motile, tumorigenic and metastatic ability of CRC cells. Enhancing Wnt/β-catenin signaling by the inhibition of GSK3β resulted in increased endogenous CTSD levels, suggesting the involvement of the Wnt/β-catenin pathway in CTSD expression. In human CRC tissue, CTSD was detected in epithelial cells and in the stromal compartment at the more invasive areas of the tumor, but not in the normal mucosa, indicating that CTSD plays an essential role in CRC progression.

Protein expression of close homologue of L1 (CHL1) is a marker for overall survival in non-small cell lung cancer (NSCLC)

BACKGROUND

The cell adhesion molecule close homologue of L1 (CHL1) is a potential tumour suppressor and was recently detected in non-small cell lung cancer (NSCLC) specimens. The expression pattern, prognostic, and functional role of CHL1 in NSCLCs is unknown.

METHODS

We evaluated the protein expression of CHL1 by immunohistochemistry in 2161 NSCLC patients based on a tissue microarray. The results were correlated with clinical, histopathological, and patient survival data (Chi square test, t test, and log-rank test, respectively). A multivariate analysis (Cox regression) was performed to validate its impact on patients' survival.

RESULTS

CHL1 was expressed in NSCLC patients and was significantly overexpressed in lung adenocarcinomas and squamous cell carcinomas compared to neuroendocrine and large cell carcinomas of the lung (p < 0.001). CHL1 expression was associated with the T stage in adenocarcinomas (p = 0.011) and with metastatic lymph node status and UICC stage in squamous cell carcinomas (p = 0.034 and p = 0.035, respectively). Increased CHL1 expression was associated with improved survival in univariate (p = 0.031) and multivariate analyses (odds ratio 0.797, 95% confidence interval 0.677-0.939, p = 0.007).

CONCLUSION

The prognostic significance of CHL1 makes it a potential prognostic and therapeutic target and underlines its role as a tumour suppressor. Further validation studies and functional analyses are needed to investigate its potential role in tumourigenesis and dissemination.

Functions of the APC tumor suppressor protein dependent and independent of canonical WNT signaling: implications for therapeutic targeting

The acquisition of biallelic mutations in the APC gene is a rate-limiting step in the development of most colorectal cancers and occurs in the earliest lesions. APC encodes a 312-kDa protein that localizes to multiple subcellular compartments and performs diverse functions. APC participates in a cytoplasmic complex that promotes the destruction of the transcriptional licensing factor β-catenin; APC mutations that abolish this function trigger constitutive activation of the canonical WNT signaling pathway, a characteristic found in almost all colorectal cancers. By negatively regulating canonical WNT signaling, APC counteracts proliferation, promotes differentiation, facilitates apoptosis, and suppresses invasion and tumor progression. APC further antagonizes canonical WNT signaling by interacting with and counteracting β-catenin in the nucleus. APC also suppresses tumor initiation and progression in the colorectal epithelium through functions that are independent of canonical WNT signaling. APC regulates the mitotic spindle to facilitate proper chromosome segregation, localizes to the cell periphery and cell protrusions to establish cell polarity and appropriate directional migration, and inhibits DNA replication by interacting directly with DNA. Mutations in APC are often frameshifts, insertions, or deletions that introduce premature stop codons and lead to the production of truncated APC proteins that lack its normal functions and possess tumorigenic properties. Therapeutic approaches in development for the treatment of APC-deficient tumors are focused on the inhibition of canonical WNT signaling, especially through targets downstream of APC in the pathway, or on the restoration of wild-type APC expression.

RETRACTED: LEF-1 gene silencing inhibits pulmonary vascular remodeling and occurrence of pulmonary arterial hypertension through the β-catenin signaling pathway

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the authors as the validity of the pulmonary vascular remodeling indicators cannot be guaranteed. The authors tried post publication to reproduce the results of the cell proliferation and cell aging, however they were not able to confirm the data that was presented by the article.

Genes and Pathways Regulated by Androgens in Human Neural Cells, Potential Candidates for the Male Excess in Autism Spectrum Disorder

BACKGROUND

Prenatal exposure to androgens during brain development in male individuals may participate to increase their susceptibility to develop neurodevelopmental disorders such as autism spectrum disorder (ASD) and intellectual disability. However, little is known about the action of androgens in human neural cells.

METHODS

We used human neural stem cells differentiated from embryonic stem cells to investigate targets of androgens.

RESULTS

RNA sequencing revealed that treatment with dihydrotestosterone (DHT) leads to subtle but significant changes in the expression of about 200 genes, encoding proteins of extracellular matrix or involved in signal transduction of growth factors (e.g., insulin/insulin growth factor 1). We showed that the most differentially expressed genes (DEGs), RGCC, RNF144B, NRCAM, TRIM22, FAM107A, IGFBP5, and LAMA2, are reproducibly regulated by different androgens in different genetic backgrounds. We showed, by overexpressing the androgen receptor in neuroblastoma cells SH-SY5Y or knocking it down in human neural stem cells, that this regulation involves the androgen receptor. A chromatin immunoprecipitation combined with direct sequencing analysis identified androgen receptor-bound sequences in nearly half of the DHT-DEGs and in numerous other genes. DHT-DEGs appear enriched in genes involved in ASD (ASXL3, NLGN4X, etc.), associated with ASD (NRCAM), or differentially expressed in patients with ASD (FAM107A, IGFBP5). Androgens increase human neural stem cell proliferation and survival in nutrient-deprived culture conditions, with no detectable effect on regulation of neurite outgrowth.

CONCLUSIONS

We characterized androgen action in neural progenitor cells, identifying DHT-DEGs that appear to be enriched in genes related to ASD. We also showed that androgens increase proliferation of neuronal precursors and protect them from death during their differentiation in nutrient-deprived conditions.

The intestinal stem cell regulating gene ASCL2 is required for L1-mediated colon cancer progression

Aberrant Wnt/β-catenin signaling is a common event during human colorectal cancer (CRC) development. Previously, we characterized members of the L1 family of cell adhesion receptors as targets of β-catenin-LEF1/TCF transactivation that are expressed at the invasive CRC tissue edge. Overexpression of L1 in CRC cells confers enhanced motility, tumorigenesis and liver metastasis. We identified several downstream targets of L1-mediated signaling that are considered key intestinal stem cell signature genes. Here, we investigated the involvement of ASCL2, a Wnt target gene and key determinant of intestinal stem cell state, in L1-mediated CRC progression. In L1 overexpressing CRC cells we found an increase in ASCL2, a decrease in E-cadherin and accumulation of nuclear β-catenin, β-catenin-LEF1/TCF transactivation and target gene expression. The increase in ASCL2 by L1 overexpression enhanced ASCL2 target gene expression, conferred increased motility, tumorigenesis and metastasis, similar to L1 overexpression. Suppression of ASCL2 in cells expressing L1 blocked these tumorigenic properties. In human CRC tissue, ASCL2 was detected in the nuclei of cells at invasive areas of the tumor that also expressed L1. The results suggest that increased ASCL2 expression is a critical step in L1-mediated CRC progression.

Inhibition of hepatocellular carcinoma tumorigenesis by curcumin may be associated with CDKN1A and CTGF

This study aimed to explore crucial genes, transcription factors (TFs), and microRNAs (miRNAs) associated with the effects of curcumin against hepatocellular carcinoma (HCC). We downloaded data (GSE59713) from Gene Expression Omnibus to analyze differentially expressed genes (DEGs) between curcumin-treated and untreated HCC cell lines. Then, we identified the disease ontology (DO) and functional enrichment analysis of these DEGs and analyzed their protein-protein interactions (PPIs). Additionally, we constructed TF-target gene and miRNA-target gene regulatory networks and explored the potential functions of these DEGs. Finally, we detected the expression of CDKN1A, CTGF, LEF1 TF and MIR-19A regulated by curcumin in PLC/PRF/5 cells using RT-PCR. In total, 345 upregulated and 212 downregulated genes were identified. The main enriched pathway of upregulated genes was the TNF signaling pathway. The downregulated genes were significantly enriched in TGF-beta signaling pathway. In addition, most DEGs were significantly enriched in DO terms such as liver cirrhosis, hepatitis, hepatitis C and cholestasis (eg., CTGF). In the constructed PPI network, CDKN1A and CTGF were the key proteins. Moreover, LEF1, CDKN1A, and miR-19A that regulated CTGF were highlighted in the regulatory networks. Furthermore, the expression of CDKN1A, CTGF, LEF1 TF and miR-19A regulated by curcumin in PLC/PRF/5 cells was consistent with the aforementioned bioinformatics analysis results. To conclude, curcumin might exert its protective effects against HCC tumorigenesis by downregulating LEF1 and downregulating CTGF regulated by MIR-19A and upregulating CDKN1A expression.

Conditional knockout of N-Myc and STAT interactor disrupts normal mammary development and enhances metastatic ability of mammary tumors

The process of organ development requires a delicate balance between cellular plasticity and differentiation. This balance is disrupted in cancer initiation and progression. N-Myc and STAT interactor (NMI: human or Nmi: murine) has emerged as a relevant player in the etiology of breast cancer. However, a fundamental understanding of its relevance to normal mammary biology is lacking. To gain insight into its normal function in mammary gland, we generated a mammary-specific Nmi knockout mouse model. We observed that Nmi protein expression is induced in mammary epithelium at the onset of pregnancy, in luminal cells and persists throughout lactation. Nmi knockout results in a precocious alveolar phenotype. These alveoli exhibit an extensive presence of nuclear β-catenin and enhanced Wnt/β-catenin signaling. The Nmi knockout pubertal ductal tree shows enhanced invasion of the mammary fatpad and increased terminal end bud numbers. Tumors from Nmi null mammary epithelium show a significant enrichment of poorly differentiated cells with elevated stem/progenitor markers, active Wnt/β-catenin signaling, highly invasive morphology as well as, increased number of distant metastases. Our study demonstrates that Nmi has a distinct role in the differentiation process of mammary luminal epithelial cell compartment and developmental aberrations resulting from Nmi absence contribute to metastasis and demonstrates that aberration in normal developmental program can lead to metastatic disease, highlighting the contribution and importance of luminal progenitor cells in driving metastatic disease.

CD271 determines migratory properties of melanoma cells

Melanoma cell expression of the nerve growth factor receptor CD271 is associated with stem-like properties. However, the contributing role of the receptor in melanoma cell migration is elusive. Here, we explored extracranial (skin, soft tissue, lymph node and liver, n = 13) and matched brain metastases (BM, n = 12) and observed a heterogeneous distribution of phenotypically distinct subsets of CD271⁺ cells. In addition, we observed that CD271 expression gradually rises along with melanoma progression and metastasis by exploration of publicly available expression data of nevi, primary melanoma (n = 31) and melanoma metastases (n = 54). Furthermore, we observed highest levels of CD271 in BM. Sub-clustering identified 99 genes differentially expressed among CD271^high and CD271^low (p < 0.05) BM-subgroups. Comparative analysis of subsets revealed increased ( ≥ 1.5fold, log2) expression of migration-associated genes and enrichment of CD271-responsible genes involved in DNA-repair and stemness. Live cell-imaging based scratch-wound assays of melanoma cells with stable knock-down of CD271 revealed a significantly reduced cell migration (3.9fold, p = 1.2E-04) and a reduced expression of FGF13, CSPG4, HMGA2 and AKT3 major candidate regulatory genes of melanoma cell migration. In summary, we provide new insights in melanoma cell migration and suggest that CD271 serves as a candidate regulator, sufficient to determine cellular properties of melanoma brain metastatic cells.

Copy number variation, increased gene expression, and molecular mechanisms of neurofascin in lung cancer

Metastasis and cell adhesion are key aspects of cancer progression. Neurofascin (NFASC) is a member of the immunoglobulin superfamily of adhesion molecules and, while studies on NFASC are inadequate, other members have been indicated pivotal roles in cancer progression and metastasis. This study aimed at increasing the knowledge on the involvement of adhesion molecules in lung cancer progression by studying the regulation and role of NFASC in non‐small cell lung cancer (NSCLC). Here, copy number variations in the NFASC gene were analyzed in tumor and non‐tumorous lung tissues of 204 NSCLC patients. Frequent gene amplifications (OR = 4.50, 95%CI: 2.27‐8.92, P ≤ 0.001) and increased expression of NFASC (P = 0.034) were identified in tumors of NSCLC patients. Furthermore, molecular mechanisms of NFASC in lung cancer progression were evaluated by investigating the effects of NFASC silencing on cell proliferation, viability, migration, and invasion using siRNA technology in four NSCLC cell lines. Silencing of NFASC did not affect cell proliferation or viability but rather decreased NSCLC cell migration (P ≤ 0.001) and led to morphological changes, rearrangements in the actin cytoskeleton and changes in F‐actin networks in migrating NSCLC cell lines. This study is the first to report frequent copy number gain and increased expression of NFASC in NSCLC. Moreover, these data suggest that NFASC is a novel regulator of NSCLC cell motility and support a role of NFASC in the regulation of NSCLC progression.

A point mutation in the extracellular domain of L1 blocks its capacity to confer metastasis in colon cancer cells via CD10

The neural L1 transmembrane cell adhesion receptor of the immunoglobulin-like family is a target gene of Wnt-β-catenin signaling in human colorectal cancer (CRC) cells and is expressed at the invasive edge of the tumor tissue. L1 overexpression in cultured CRC cells confers enhanced proliferation, motility and liver metastasis. We have analyzed the mechanisms of L1-mediated signaling in CRC cells by using various point mutations in the L1 ectodomain that are known to cause severe genetically inherited mental retardation disorders in patients. We found that all such L1 ectodomain mutations abolish the ability of L1 to confer metastatic properties in CRC cells. Using gene array analysis, we identified L1-mutation-specific gene expression signatures for the L1/H210Q and L1/D598N mutations. We identified CD10, a metalloprotease (neprilysin, neutral endopeptidase) and a gene that is specifically induced in CRC cells by L1 in an L1/H210Q mutation-specific manner. CD10 expression was required for the L1-mediated induction of cell proliferation, motility and metastasis, as suppression of CD10 levels in L1-expressing CRC cells abolished the L1 effects on CRC progression. The signaling from L1 to CD10 was mediated through the L1-ezrin-NF-κB pathway. In human CRC tissue L1 and CD10 were localized in partially overlapping regions in the more invasive areas of the tumor tissue. The results suggest that CD10 is a necessary component conferring the L1 effects in CRC cells. The identification of gene expression patterns of L1-domain-specific point mutations may provide novel markers and targets for interfering with L1-mediated CRC progression.

Novel molecular signatures in mononuclear cell populations from patients with systemic lupus erythematosus

To gain novel insights into the immunopathogenesis of systemic lupus erythematosus we have analyzed gene expression data from isolated CD4⁺ T cells, CD8⁺ T cells, CD19⁺ B cells, and CD56⁺ NK-cell enriched peripheral blood cell fractions from patients and healthy donors. As predicted, type I interferon-inducible gene transcripts are overexpressed in all populations. Transcripts preferentially expressed in SLE CD4⁺ and CD8⁺ T cells include those associated with Tregulatory and Th17 effector cell programs, respectively, but in each case additional transcripts predicted to limit differentiation of those effector cells are detected. Evidence for involvement of the Wnt/β-catenin pathway was observed in both B and T cell fractions, and novel transcripts were identified in each cell population. These data point to disrupted T effector cell differentiation and the Wnt/β-catenin pathway as contributors to immune dysfunction in SLE while further supporting a central role for the type I interferon pathway in lupus.

Clusterin, a gene enriched in intestinal stem cells, is required for L1-mediated colon cancer metastasis

Hyperactive Wnt signaling is a common feature in human colorectal cancer (CRC) cells. A central question is the identification and role of Wnt/β-catenin target genes in CRC and their relationship to genes enriched in colonic stem cells, since Lgr5+ intestinal stem cells were suggested to be the cell of CRC origin. Previously, we identified the neural immunoglobulin-like adhesion receptor L1 as a Wnt/β-catenin target gene localized in cells at the invasive front of CRC tissue and showed that L1 expression in CRC cells confers enhanced motility and liver metastasis. Here, we identified the clusterin (CLU) gene that is also enriched in Lgr5+ intestinal stem cells, as a gene induced during L1-mediated CRC metastasis. The increase in CLU levels by L1 in CRC cells resulted from transactivation of CLU by STAT-1. CLU overexpression in CRC cells enhanced their motility and the reduction in CLU levels in L1 overexpressing cells suppressed the ability of L1 to confer increased tumorigenesis and liver metastasis. Genes induced during L1-mediated CRC cell metastasis and enriched in intestinal stem cells might be important for both CRC progression and colonic epithelium homeostasis.

The Wnt Target Gene L1 in Colon Cancer Invasion and Metastasis

The Wnt-β-catenin signaling pathway is highly conserved during evolution and determines normal tissue homeostasis. Hyperactivation of Wnt-β-catenin signaling is a characteristic feature of colorectal cancer (CRC) development. β-catenin is a major transducer of the Wnt signal from the cytoplasm into the nucleus where it acts as a co-transcriptional activator of β-catenin-TCF target genes. β-catenin is also required for linking cadherin type cell-cell adhesion receptors to the cytoskeleton, and consequently Wnt-β-catenin signaling is an attractive system for investigating the role of adhesion-mediated signaling in both normal intestinal tissue homeostasis and CRC development. In this review, we summarize our studies on one Wnt-β-catenin target gene, L1, a member of the immunoglobulin-like cell adhesion transmembrane receptor family. We describe the mechanisms of L1-mediated signaling in CRC cells, its exclusive localization in invasive areas of CRC tissue, and its ability to increase cell motility and confer metastasis to the liver. We discuss the activation (by L1) of genes via an ezrin-NF-κB pathway and the induction of genes also found in the intestinal stem cell signature. By studying L1 (adhesion)-mediated signaling, we expect to learn about mechanisms regulating both normal intestinal homeostasis and CRC development.

DACH1 is a novel predictive and prognostic biomarker in hepatocellular carcinoma as a negative regulator of Wnt/β-catenin signaling

The cell fate determination factor Dachshund (DACH1) functions as a novel suppressor in the progression of various neoplasms. Previous study has suggested that hypermethylation of promoter region was responsible for the reduction of DACH1 expression in hepatocellular carcinoma (HCC), and associated with the progression of HCC, but the clinical significance and the exact molecular mechanisms of DACH1 in the progression of HCC remain unclear. In this study, we employed public microarray data analysis and tissue microarrays (TMAs) technologies and showed that DACH1 expression was reduced in HCC even at early stage and associated with the tumor progression. Notably, Kaplan-Meier analysis further indicated DACH1 could be an independent prognostic factor for the overall survival of HCC. Further, mechanistic studies revealed that overexpression of DACH1 inhibited the growth and migration of HCC cell line, which were dependent in part on the inactivation of Wnt pathway via phosphorylation of GSK3β to suppress β-catenin. In agreement, the abundance of DACH1 was inversely correlated with several Wnt target genes. Collectively, our study indicated β-catenin is a novel target of DACH1 in HCC.

Gene Expression Profile of Dendritic Cell-Tumor Cell Hybrids Determined by Microarrays and Its Implications for Cancer Immunotherapy

Background. Dendritic cell- (DC-) tumor fusion cells stimulate effective in vivo antitumor responses. However, therapeutic approaches are dependent upon the coadministration of exogenous 3rd signals. The purpose of this study was to determine the mechanisms for inadequate 3rd signaling by electrofused DC-tumor cell hybrids. Methods. Murine melanoma cells were fused with DCs derived from C57BL/6 mice. Quantitative real-time PCR (qPCR) was used to determine relative changes in Th (T helper) 1 and Th2 cytokine gene expression. In addition, changes in gene expression of fusion cells were determined by microarray. Last, cytokine secretion by fusion cells upon inhibition of signaling pathways was analyzed by ELISA. Results. qPCR analyses revealed that fusion cells exhibited a downregulation of Th1 associated cytokines IL-12 and IL-15 and an upregulation of the Th2 cytokine IL-4. Microarray studies further showed that the expression of chemokines, costimulatory molecules, and matrix-metalloproteinases was deregulated in fusion cells. Lastly, inhibitor studies demonstrate that inhibition of the PI3K/Akt/mTOR signaling pathway could restore the secretion of bioactive IL-12p70 by fusion cells. Conclusion. Our results suggest that combining fusion cell-based vaccination with administration of inhibitors of the PI3K/Akt/mTOR signaling pathway may enhance antitumor responses in patients.

Mice with Hepatic Loss of the Desmosomal Protein γ-Catenin Are Prone to Cholestatic Injury and Chemical Carcinogenesis

γ-Catenin, an important component of desmosomes, may also participate in Wnt signaling. Herein, we dissect the role of γ-catenin in liver by generating conditional γ-catenin knockout (KO) mice and assessing their phenotype after bile duct ligation (BDL) and diethylnitrosamine-induced chemical carcinogenesis. At baseline, KO and wild-type littermates showed comparable serum biochemistry, liver histology, and global gene expression. β-Catenin protein was modestly increased without any change in Wnt signaling. Desmosomes were maintained in KO, and despite no noticeable changes in gene expression, differential detergent fractionation revealed quantitative and qualitative changes in desmosomal cadherins, plaque proteins, and β-catenin. Enhanced association of β-catenin to desmoglein-2 and plakophilin-3 was observed in KO. When subjected to BDL, wild-type littermates showed specific changes in desmosomal protein expression. In KO, BDL deteriorated baseline compensatory changes, which manifested as enhanced injury and fibrosis. KO also showed enhanced tumorigenesis to diethylnitrosamine treatment because of Wnt activation, as also verified in vitro. γ-Catenin overexpression in hepatoma cells increased its binding to T-cell factor 4 at the expense of β-catenin-T-cell factor 4 association, induced unique target genes, affected Wnt targets, and reduced cell proliferation and viability. Thus, γ-catenin loss in liver is basally well tolerated. However, after insults like BDL, these compensations at desmosomes fail, and KO show enhanced injury. Also, γ-catenin negatively regulates tumor growth by affecting Wnt signaling.

Chromatin-Remodeling-Factor ARID1B Represses Wnt/β-Catenin Signaling

The link of chromatin remodeling to both neurodevelopment and cancer has recently been highlighted by the identification of mutations affecting BAF chromatin-remodeling components, such as ARID1B, in individuals with intellectual disability and cancer. However, the underlying molecular mechanism(s) remains unknown. Here, we show that ARID1B is a repressor of Wnt/β-catenin signaling. Through whole-transcriptome analysis, we find that in individuals with intellectual disability and ARID1B loss-of-function mutations, Wnt/β-catenin target genes are upregulated. Using cellular models of low and high Wnt/β-catenin activity, we demonstrate that knockdown of ARID1B activates Wnt/β-catenin target genes and Wnt/β-catenin-dependent transcriptional reporters in a β-catenin-dependent manner. Reciprocally, forced expression of ARID1B inhibits Wnt/β-catenin signaling downstream of the β-catenin destruction complex. Both endogenous and exogenous ARID1B associate with β-catenin and repress Wnt/β-catenin-mediated transcription through the BAF core subunit BRG1. Accordingly, mutations in ARID1B leading to partial or complete deletion of its BRG1-binding domain, as is often observed in intellectual disability and cancers, compromise association with β-catenin, and the resultant ARID1B mutant proteins fail to suppress Wnt/β-catenin signaling. Finally, knockdown of ARID1B in mouse neuroblastoma cells leads to neurite outgrowth through β-catenin. The data suggest that aberrations in chromatin-remodeling factors, such as ARID1B, might contribute to neurodevelopmental abnormalities and cancer through deregulation of developmental and oncogenic pathways, such as the Wnt/β-catenin signaling pathway.

Identification of diagnostic markers in colorectal cancer via integrative epigenomics and genomics data

Apart from genetic mutations, epigenetic alteration is a common phenomenon that contributes to neoplastic transformation in colorectal cancer. Transcriptional silencing of tumor-suppressor genes without changes in the DNA sequence is explained by the existence of promoter hypermethylation. To test this hypothesis, we integrated the epigenome and transcriptome data from a similar set of colorectal tissue samples. Methylation profiling was performed using the Illumina InfiniumHumanMethylation27 BeadChip on 55 paired cancer and adjacent normal epithelial cells. Fifteen of the 55 paired tissues were used for gene expression profiling using the Affymetrix GeneChip Human Gene 1.0 ST array. Validation was carried out on 150 colorectal tissues using the methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) technique. PCA and supervised hierarchical clustering in the two microarray datasets showed good separation between cancer and normal samples. Significant genes from the two analyses were obtained based on a ≥2-fold change and a false discovery rate (FDR) p-value of <0.05. We identified 1,081 differentially hypermethylated CpG sites and 36 hypomethylated CpG sites. We also found 709 upregulated and 699 downregulated genes from the gene expression profiling. A comparison of the two datasets revealed 32 overlapping genes with 27 being hypermethylated with downregulated expression and 4 hypermethylated with upregulated expression. One gene was found to be hypomethylated and downregulated. The most enriched molecular pathway identified was cell adhesion molecules that involved 4 overlapped genes, JAM2, NCAM1, ITGA8 and CNTN1. In the present study, we successfully identified a group of genes that showed methylation and gene expression changes in well-defined colorectal cancer tissues with high purity. The integrated analysis gives additional insight regarding the regulation of colorectal cancer-associated genes and their underlying mechanisms that contribute to colorectal carcinogenesis.

Induction of the intestinal stem cell signature gene SMOC-2 is required for L1-mediated colon cancer progression

Overactivation of Wnt-β-catenin signaling, including β-catenin-TCF target gene expression, is a hallmark of colorectal cancer (CRC) development. We identified the immunoglobulin family of cell-adhesion receptors member L1 as a β-catenin-TCF target gene preferentially expressed at the invasive edge of human CRC tissue. L1 can confer enhanced motility and liver metastasis when expressed in CRC cells. This ability of L1-mediated metastasis is exerted by a mechanism involving ezrin and the activation of NF-κB target genes. In this study, we identified the secreted modular calcium-binding matricellular protein-2 (SMOC-2) as a gene activated by L1-ezrin-NF-κB signaling. SMOC-2 is also known as an intestinal stem cell signature gene in mice expressing Lgr5 in cells at the bottom of intestinal crypts. The induction of SMOC-2 expression in L1-expressing CRC cells was necessary for the increase in cell motility, proliferation under stress and liver metastasis conferred by L1. SMOC-2 expression induced a more mesenchymal like phenotype in CRC cells, a decrease in E-cadherin and an increase in Snail by signaling that involves integrin-linked kinase (ILK). SMOC-2 was localized at the bottom of normal human colonic crypts and at increased levels in CRC tissue with preferential expression in invasive areas of the tumor. We found an increase in Lgr5 levels in CRC cells overexpressing L1, p65 or SMOC-2, suggesting that L1-mediated CRC progression involves the acquisition of a stem cell-like phenotype, and that SMOC-2 elevation is necessary for L1-mediated induction of more aggressive/invasive CRC properties.

Modulation of cytoskeletal dynamics by mammalian nucleoside diphosphate kinase (NDPK) proteins

Nucleoside diphosphate kinase (NDPK) proteins comprise a family of ten human isoforms that participate in the regulation of multiple cellular processes via enzymatic and nonenzymatic functions. The major enzymatic function of NDPKs is the generation of nucleoside triphosphates, such as guanosine triphosphate (GTP). Mechanisms behind the nonenzymatic NDPK functions are not clear but likely involve context-dependent signaling roles of NDPK within multi-protein complexes. This is most evident for NDPK-A, which is encoded by the human NME1 gene, the first tumor metastasis suppressor gene to be identified. Understanding which protein interactions are most relevant for the biological and metastasis-related functions of NDPK will be important in the potential utilization of NDPK as a disease target. Accumulating evidence suggests that NDPK interacts with and affects various components and regulators of the cytoskeleton, including actin-binding proteins, intermediate filaments, and cytoskeletal attachment structures (adherens junctions, desmosomes, and focal adhesions). We review the existing literature on this topic and highlight outstanding questions and potential future directions that should clarify the impact of NDPK on the different cytoskeletal systems.

Desmoglein 3: a help or a hindrance in cancer progression?

Desmoglein 3 is one of seven desmosomal cadherins that mediate cell-cell adhesion in desmosomes. Desmosomes are the intercellular junctional complexes that anchor the intermediate filaments of adjacent cells and confer strong cell adhesion thus are essential in the maintenance of tissue architecture and structural integrity. Like adherens junctions, desmosomes function as tumour suppressors and are down regulated in the process of epithelial-mesenchymal transition and in tumour cell invasion and metastasis. However, recently several studies have shown that various desmosomal components, including desmoglein 3, are up-regulated in cancer with increased levels of expression correlating with the clinical stage of malignancy, implicating their potentiality to serve as a diagnostic and prognostic marker. Furthermore, in vitro studies have demonstrated that overexpression of desmoglein 3 in cancer cell lines activates several signal pathways that have an impact on cell morphology, adhesion and locomotion. These additional signalling roles of desmoglein 3 may not be associated to its adhesive function in desmosomes but rather function outside of the junctions, acting as a key regulator in the control of actin based cellular processes. This review will discuss recent advances which support the role of desmoglein 3 in cancer progression.

CYP2S1 depletion enhances colorectal cell proliferation is associated with PGE2-mediated activation of β-catenin signaling

Colorectal epithelial cancer is one of the most common cancers in the world and its 5-year survival rate is still relatively low. Cytochrome P450 (CYP) enzymes in epithelial cells lining the alimentary tract play an important role in the oxidative metabolism of a wide range of xenobiotics, including (pro-)carcinogens and endogenous compounds. Although CYP2S1, a member of CYP family, strongly expressed in many extrahepatic tissues, the role of CYP2S1 in cancer remains unclear. To investigate whether CYP2S1 involves in colorectal carcinogenesis, cell proliferation was analyzed in HCT116 cells depleted of CYP2S1 using small hairpin interfering RNA. Our data show that CYP2S1 knockdown promotes cell proliferation through increasing the level of endogenous prostaglandin E2(PGE2). PGE2, in turn, reduces phosphorylation of β-catenin and activates β-catenin signaling, which contributes to the cell proliferation. Furthermore, CYP2S1 knockdown increase tumor growth in xenograft mouse model. In brief, these results demonstrate that CYP2S1 regulates colorectal cancer growth through associated with PGE2-mediated activation of β-catenin signaling.

STAT3 paradoxically stimulates β-catenin expression but inhibits β-catenin function

Wnt signalling and the signal transducer and activator of transcription 3 (STAT3) are oncogenic signalling pathways which are deregulated in colorectal cancer (CRC). Here we investigated the interaction of these two pathways. Firstly, we investigated biochemical interaction by inhibiting STAT3 and β-catenin (through gene knock-down and dominant-negative TCF4 expression) in nine CRC cell lines. β-catenin inhibition did not affect STAT3 levels, whereas STAT3 knock-down resulted in reduced β-catenin mRNA and protein levels. The reduction in β-catenin protein was not prevented by proteasome inhibition, and IL6-induced STAT3 activation resulted in increased β-catenin mRNA. This suggests that STAT3 positively regulates β-catenin (at a transcriptional level) and evaluation of 44 CRCs by immunostaining supported this by showing an association between nuclear STAT3 expression and nuclear β-catenin (P = 0.022). We tested the functional interaction between STAT3 and Wnt signalling by knocking down STAT3 and β-catenin individually and in combination. Knock-down of β-catenin and STAT3 individually inhibited cell proliferation (P < 0. 001 for each) through G1 arrest. However, simultaneous knock-down of STAT3 and β-catenin had a significantly weaker effect than knock-down of β-catenin alone (P < 0.01). Knock-down of STAT3 and β-catenin, individually and together, inhibited cell motility (P < 0.001) without evidence of interaction. We conclude that STAT3 regulates β-catenin but β-catenin does not regulate STAT3. The STAT3/β-catenin interaction is complex but may reduce the proliferative activity of β-catenin possibly by taking β-catenin protein beyond the optimal level. This may indicate biological differences in tumours where both STAT3 and β-catenin are activated compared to those where only one is activated.

PLEKHA5 as a Biomarker and Potential Mediator of Melanoma Brain Metastasis

PURPOSE

Approximately 40% of patients with metastatic melanoma develop brain metastases. Our purpose was to identify genes aberrantly expressed in melanoma that might be associated with propensity for brain homing.

EXPERIMENTAL DESIGN

We studied gene expression profiles in a cell line model of brain metastasis (cerebrotropic A375Br cells vs. parental A375P cells) and compared them with profiles of patients who developed early brain metastases and who did not. A tissue microarray containing 169 metastatic melanoma cases with variable time to brain metastasis was constructed to further study marker expression by quantitative immunofluorescence. An in vitro model of the blood brain barrier (BBB) was generated to evaluate potential mediators of brain metastases.

RESULTS

PLEKHA5 was differentially expressed in both the A375 cell line model and patient samples subjected to gene expression profiling. At the protein level, by quantitative immunofluorescence, PLEKHA5 was associated with decreased brain metastasis-free survival. PLEKHA5 overexpression was not associated with other metastatic sites. Knockdown of PLEKHA5 decreases the viability of A375Br cells, inhibits BBB transmigration and invasion in vitro. Similar results were found with YUMUL cells, cultured from a patient with overwhelming brain metastases. PLEKHA5 knockdown did not affect the viability of A375P cells.

CONCLUSIONS

PLEKHA5 expression in melanoma tumors was associated with early development of brain metastases. Inhibition of PLEKHA5 might decrease passage across the BBB and decrease proliferation and survival of melanoma cells both in the brain and in extracerebral sites.