Expression of nuclear beta-catenin and c-myc is correlated with tumor size but not with proliferative activity of colorectal adenomas

miR-575/RIPK4 axis modulates cell cycle progression and proliferation by inactivating the Wnt/β-catenin signaling pathway through inhibiting RUNX1 in colon cancer

Receptor interacting protein serine/threonine kinase 4 (RIPK4) is widely involved in human cancer development. Nevertheless, its role in colon cancer (COAD) has not been elucidated till now. Our research aimed at exploring the function and underlying molecular mechanism of RIPK4 in COAD progression. Through bioinformatic analyses and RT-qPCR, RIPK4 was discovered to be increased in COAD cells and tissues, and its high level predicted poor prognosis. Loss-of-function assays revealed that RIPK4 silencing suppressed COAD cell growth, induced cell cycle arrest, and enhanced cell apoptosis. In vivo experiments also proved that tumor growth was inhibited by silencing of RIPK4. Luciferase reporter assay validated that RIPK4 was targeted and negatively regulated by miR-575. Western blotting demonstrated that Wnt3a, phosphorylated (p)-GSK-3β, and cytoplasmic and nuclear β-catenin protein levels, β-catenin nuclear translocation, and Cyclin D1, CDK4, Cyclin E, and c-Myc protein levels were reduced by RIPK4 knockdown, which however was reversed by treatment with LiCl, the Wnt/β-catenin pathway activator. LiCl also offset the influence of RIPK4 knockdown on COAD cell growth, cell cycle process, and apoptosis. Finally, RIPK4 downregulation reduced RUNX1 level, which was upregulated in COAD and its high level predicted poor prognosis. RIPK4 is positively associated with RUNX1 in COAD. Overexpressing RUNX1 antagonized the suppression of RIPK4 knockdown on RUNX1, Wnt3a, p-GSK-3β, cytoplasmic β-catenin, nuclear β-catenin, Cyclin D1, CDK4, Cyclin E, and c-Myc levels. Collectively, miR-575/RIPK4 axis repressed COAD progression via inactivating the Wnt/β-catenin pathway through downregulating RUNX1.

Primary Signet Ring Cell/Histiocytoid Carcinoma of the Eyelid: Clinicopathologic Analysis with Evaluation of the E-Cadherin/β-Catenin Complex and Associated Genetic Alterations

Signet Ring Cell (SRC)/Histiocytoid carcinoma of the eyelid is a rare neoplasm that shares histological and immunohistochemical similarities with diffuse gastric cancer and breast lobular carcinoma. The CDH1 gene, which encodes the E-cadherin protein, is the best known gene associated with these tumors. The structural and functional integrity of E-cadherin is regulated by interconnecting molecular pathways which might participate in the development of this disease. Hence, we analyzed the protein expression in key genes in E-cadherin-related pathways associated with primary SRC/Histiocytoid carcinoma of the eyelid. SRC/Histiocytoid carcinoma diagnosed in the eyelid/orbit at MD Anderson Cancer Center from 1990 to 2016 were evaluated. Clinicopathologic findings were studied to confirm the primary site of origin. Immunohistochemical studies for the expression of E-cadherin, β-catenin, c-Myc, Cyclin D1, Src, and p53 were analyzed. Next generation sequencing for the detection of somatic mutations was performed on each tumor with matched normal tissue, examining 50 cancer-related genes. Four primary SRC/Histiocytoid carcinomas of the eyelid were diagnosed in four male patients aged 40-82 years. Immunohistochemically, two tumors with loss of E-cadherin expression had weak β-catenin and low cytoplasmic staining for Src while the other two cases with intact E-cadherin showed strong β-catenin expression and high cytoplasmic expression for Src. Cyclin D1 was focally positive in three cases. Somatic mutations in CDH1, PIK3CA, and TP53 genes were detected in two cases. Our results suggest an abnormality in the convergence of E-cadherin/β-catenin pathways which may promote tumorigenesis by inducing expression of oncogenes such as Cyclin D1 and C-Myc. Mutations in CDH1, PIK3CA, and TP53 genes could induce E-cadherin dysfunction which takes part in the development and progression of this malignancy.

Does Loss of Immunohistochemical Expression of Glypican 3 in Oral Squamous Cell Carcinoma Play a Role in the Wnt/β-catenin Signaling Pathway?

Glypican 3 (GPC3) is a cell membrane protein and plays a dual role, as a tumor suppressor and oncogene, depending on its structure. It is known to regulate the Wnt/β-catenin signaling pathway and affect cell growth and proliferation. β-catenin plays a major oncogenic role in progression of oral squamous cell carcinoma (OSCC); thus, this study aimed to explore the relationship between β-catenin and GPC3 in OSCC. Immunoexpression of GPC3 and β-catenin was evaluated semiquantitatively in tumor tissue (n=80) and normal oral mucosa tissue (n=20). For GPC3, the percentage of stained cells and the staining intensity were assessed. For β-catenin, the percentage of stained cells, localization, and intensity of staining were assessed at the tumor-invasive front. The Pearson correlation was used to determine the correlation between the GPC3 and β-catenin immunoreactivity. Significantly decreased expression of GPC3 (P=0.008) and a highly significant difference in the case of localization of β-catenin (P=0.0001) were observed in OSCC when compared with normal oral mucosa. Cytoplasmic expression with a shift of β-catenin expression to the nucleus was seen in OSCC in comparison with primarily membranous and membranous and cytoplasmic staining in normal mucosa. A significant difference was observed with respect to localization of stain, with β-catenin staining moving to the nuclear compartment with an increase in the tumor grade (P=0.011). No correlation was observed between β-catenin and GPC3 expression in OSCC cases. It is concluded that loss of expression of GPC3 in OSCC compared with normal oral mucosa indicates that it plays the role of a tumor suppressor gene in OSCC and its expression is therefore silenced in OSCC.

SPOCK1: a multi-domain proteoglycan at the crossroads of extracellular matrix remodeling and cancer development

The SPARC/osteonectin, CWCV and Kazal-like domains proteoglycan 1 (SPOCK1) is a highly conserved, multi-domain proteoglycan that regulates the dynamic equilibrium of extracellular matrix (ECM). Besides, SPOCK1 is one of the key regulatory genes in the tumor ECM dynamic homeostasis process, which activates many molecular signaling pathways (such as EMT process, Wnt/β-catenin, PI3K/Akt, and mTOR/S6K signaling pathways). This activation leads to ECM remodeling and promotes cell proliferation and invasion, but inhibits cell apoptosis. Whereas there is immense information about SPOCK1's roles in different biological settings, there is need for further studies that interrogate this protein as a potential therapeutic target in cancer.

Synergistic antitumor effect of 5-fluorouracil and withaferin-A induces endoplasmic reticulum stress-mediated autophagy and apoptosis in colorectal cancer cells

The development of chemo-resistance against 5-fluorouracil (5-FU) in tumor cells is one of the main debacles in colorectal cancer (CRC) patients. A recent combination of 5-FU with oxaliplatin or cetuximab drastically improves the survival rate in CRC patients; however, the toxicity issue cannot be evaded completely. Thus, searching for novel drug combinations with high specificity and low toxicity is seemingly important. Owing to the less undesirable effects of natural products on normal cells, here we investigated the synergistic antitumor effect of withaferin-A (WA) in combination with 5-FU. Our results demonstrate that the combination of WA and 5-FU induces a significant antiproliferative effect and modulates endoplasmic reticulum (ER) stress in favor of cell death in colorectal cancer (CRC) cells. Mechanistically, the combination upregulates the expression of ER stress sensors (BiP, PERK, CHOP, ATF-4, and eIF2α) and executes PERK axis mediated apoptosis in CRC cells. Additionally, the combined treatment of WA and 5-FU mediated ER stress induces autophagy and apoptosis, which were confirmed by immunoblotting, acridine orange (AO) staining and annexin-V FITC by flow cytometry. In contrast, inhibition of ER stress with salubrinal significantly decreases both autophagic and apoptotic cell populations. Moreover, pharmacological inhibition of either autophagy or apoptosis by their respective inhibitors 3-methyladenine (3-MA) or carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]-fluoro-methyl ketone (Z-VAD-FMK) decreases their respective population of cells but could not affect either of the population significantly. Finally, the combination attenuates the expression of β-catenin pathway associated proteins and arrests cell cycle at the G₂M phase in CRC cells. In summary, the combination of WA and 5-FU decreases cell viability by inducing ER stress-mediated induction of autophagy and apoptosis, inhibiting the β-catenin pathway and arresting the cell cycle at a G₂M phase in CRC cells.

ROR-α-1 inhibits the proliferation, invasion, and migration of hepatocellular carcinoma MHCC97H via downregulation of chemokine CXCL5

Hepatocarcinogenesis is a complicated process that is affected by a variety of microenvironmental factors, such as secretory chemokines and cell-extracellular matrix (ECM). Retinoic acid receptor-related orphan receptor (ROR)-α has been shown to attenuate tumor invasiveness by inducing suppressive cell microenvironment, and its low expression was associated with a worse prognosis in HCC patients. In the present study, we attempted to investigate the role and mechanism of the dominant transcript of ROR-α, ROR-α-1, in HCC development and progression. Among the four transcripts (ROR-α-1/-2/-3/-4), overexpression of ROR-α-1 dramatically suppressed the capacity of MHCC97H cells to proliferate, migrate and invade. We analyzed the differentially expressed genes in ROR-α-1-overexpressed and non-overexpressed MHCC97H cells, performed Gene Ontology (GO) enrichment analysis on these differentially-expressed genes, and found out that factors involved in the tumor microenvironment and ECM are related to the anti-tumor effects of ROR-α-1. Among these factors, chemokine CXCL5 was significantly downregulated by ROR-α-1 overexpression. Overexpression of ROR-α-1 remarkably inhibited the capacity of HCC cells to proliferate, migrate, invade, and downregulated the protein levels of β-catenin, c-Myc, Cyclin D1, and N-cadherin, suggesting the tumor-suppressive role of ROR-α-1 in MHCC97H cells. Moreover, overexpression of CXCL5 dramatically attenuated the suppressive effects of cell proliferation, migration and invasion induced by ROR-α-1 overexpression in MHCC97H, suggesting that ROR-α-1 exerts its anti-tumor effects via downregulating CXCL5. In conclusion, we demonstrate the tumor-suppressive role of ROR-α-1 in MHCC97H cells and that ROR-α-1 might play a tumor-suppressive role via regulation of chemokine CXCL5.

Novel Thienopyrimidine Derivative, RP-010, Induces β-Catenin Fragmentation and Is Efficacious against Prostate Cancer Cells

Thienopyrimidines containing a thiophene ring fused to pyrimidine are reported to have a wide-spectrum of anticancer efficacy in vitro. Here, we report for the first time that thieno[3,2-d]pyrimidine-based compounds, also known as the RP series, have efficacy in prostate cancer cells. The compound RP-010 was efficacious against both PC-3 and DU145 prostate cancer (PC) cells (IC₅₀ < 1 µM). The cytotoxicity of RP-010 was significantly lower in non-PC, CHO, and CRL-1459 cell lines. RP-010 (0.5, 1, 2, and 4 µM) arrested prostate cancer cells in G2 phase of the cell cycle, and induced mitotic catastrophe and apoptosis in both PC cell lines. Mechanistic studies suggested that RP-010 (1 and 2 µM) affected the wingless-type MMTV (Wnt)/β-catenin signaling pathway, in association with β-catenin fragmentation, while also downregulating important proteins in the pathway, including LRP-6, DVL3, and c-Myc. Interestingly, RP-010 (1 and 2 µM) induced nuclear translocation of the negative feedback proteins, Naked 1 and Naked 2, in the Wnt pathway. In addition, RP-010 (0.5, 1, 2 and 4 µM) significantly decreased the migration of PC cells in vitro. Finally, RP-010 did not produce significant toxic effects in zebrafish at concentrations of up to 6 µM. In conclusion, RP-010 may be an efficacious and relatively nontoxic anticancer compound for prostate cancer. Future mechanistic and in vivo efficacy studies are needed to optimize the hit compound RP-010 for lead optimization and clinical use.

Identification of marker genes and pathways specific to precancerous duodenal adenomas and early stage adenocarcinomas

BACKGROUND

The mechanism behind the pathogenesis and carcinogenesis of these neoplasms is not fully understood. The objective of this study was to identify genetic markers and pathways specific to precancerous duodenal adenomas and early stage adenocarcinomas through gene expression analysis.

METHODS

Gene expression profiling was performed in 4 pairs of duodenal adenoma/adenocarcinomas and corresponding matched normal tissue. Genes with consistent expression differences were identified and confirmed in 7 independent pairs. Gene set enrichment analysis (GSEA) was performed to characterize gene expression profiles of duodenal adenoma/adenocarcinomas, together with immunohistochemical staining of candidate oncogenic genes.

RESULTS

626 probes consistently demonstrated over a twofold expression difference between tumor-normal pairs. Reverse transcriptase polymerase chain reaction of genes with the most prominent difference in expression between tumors and normal mucosa (KLK7, KLK6, CEMIP, MMP7, KRT17, LGR5, G6PC, S100G, APOA1) validated the results of gene expression analysis. GSEA demonstrated a strong association between duodenal adenoma/adenocarcinomas with colorectal adenomas (p < 10^-5) and gene expression patterns seen after APC gene knockout (p < 10^-5), suggesting that the Wnt/β-catenin pathway plays a crucial role in the carcinogenesis of these neoplasms. Immunohistochemical staining of an independent group of duodenal adenomas confirmed over-accumulation of β-catenin in 80.0% (16/20).

CONCLUSIONS

Precancerous duodenal adenomas and early stage adenocarcinomas demonstrate gene expression characteristics with a strong resemblance to colorectal adenomas. The results of this study strongly suggest that upregulation of the Wnt/β-catenin pathway is the major factor involved in the initial stages of the carcinogenesis of duodenal adenocarcinomas.

MASTL induces Colon Cancer progression and Chemoresistance by promoting Wnt/β-catenin signaling

BACKGROUND

Chemotherapeutic agents that modulate cell cycle checkpoints and/or tumor-specific pathways have shown immense promise in preclinical and clinical studies aimed at anti-cancer therapy. MASTL (Greatwall in Xenopus and Drosophila), a serine/threonine kinase controls the final G2/M checkpoint and prevents premature entry of cells into mitosis. Recent studies suggest that MASTL expression is highly upregulated in cancer and confers resistance against chemotherapy. However, the role and mechanism/s of MASTL mediated regulation of tumorigenesis remains poorly understood.

METHODS

We utilized a large patient cohort and mouse models of colon cancer as well as colon cancer cells to determine the role of Mastl and associated mechanism in colon cancer.

RESULTS

Here, we show that MASTL expression increases in colon cancer across all cancer stages compared with normal colon tissue (P < 0.001). Also, increased levels of MASTL associated with high-risk of the disease and poor prognosis. Further, the shRNA silencing of MASTL expression in colon cancer cells induced cell cycle arrest and apoptosis in vitro and inhibited xenograft-tumor growth in vivo. Mechanistic analysis revealed that MASTL expression facilitates colon cancer progression by promoting the β-catenin/Wnt signaling, the key signaling pathway implicated in colon carcinogenesis, and up-regulating anti-apoptotic proteins, Bcl-xL and Survivin. Further studies where colorectal cancer (CRC) cells were subjected to 5-fluorouracil (5FU) treatment revealed a sharp increase in MASTL expression upon chemotherapy, along with increases in Bcl-xL and Survivin expression. Most notably, inhibition of MASTL in these cells induced chemosensitivity to 5FU with downregulation of Survivin and Bcl-xL expression.

CONCLUSION

Overall, our data shed light on the heretofore-undescribed mechanistic role of MASTL in key oncogenic signaling pathway/s to regulate colon cancer progression and chemo-resistance that would tremendously help to overcome drug resistance in colon cancer treatment.

Association of Helicobacter pylori with colorectal cancer development

Background: Helicobacter pylori (H. pylori) may be associated with colorectal cancer. However, the underlying mechanisms are still unclear. Objectives: Explore the serostatus of H. pylori cytotoxicity-associated gene A product (CagA) in patients with colorectal carcinoma, and assess the association of H. pylori with colorectal cancer via c-Myc and MUC-2 proteins at tumor tissues. Methods: H. pylori CagA IgG antibodies were screened using enzyme-linked immunosorbent assay (ELISA) in 30 patients with colorectal carcinoma and 30 cancer-free control subjects. Paraffin-embedded blocks were examined for the expression of c-Myc and MUC-2 protein by immunohistochemistry. Results: H. pylori CagA seropositivity increased significantly among colorectal cancer patients (p <0.05). The expression of c-Myc and MUC-2 in colorectal carcinoma patients was over-expressed (80%), and downexpressed (63%) in resection margins (p <0.05). c-Myc over-expression and MUC-2 down-expression were associated with CagA-positive rather than CagA-negative H. pylori patients. In 16 CagA seropositive vs. 14 CagA seronegative patients, the expression rate was 97.3% vs. 64.2% and 33.3% vs. 78.5% for cMyc and MUC-2, respectively. CagA IgG level was significantly higher in positive than in negative c-Myc patients (p= 0.036), and in negative than in positive MUC-2 patients (p= 0.044). c-Myc and MUC-2 were positively and inversely correlated with CagA IgG level (p <0.05). Conclusions: CagA-seropositive H. pylori is most probably associated with colorectal cancer development. Part of the underlying mechanism for such association might be via alterations in expression of MUC-2, which depletes the mucous protective layer in the colo-rectum, and c-Myc, which stimulates the growth of cancerous cells.

The G protein-coupled P2Y₆ receptor promotes colorectal cancer tumorigenesis by inhibiting apoptosis

Colorectal tumors are immersed in an array of tumor-promoting factors including extracellular nucleotides such as uridine 5'‑diphosphate (UDP). UDP is the endogenous agonist of the G protein-coupled P2Y₆ receptor (P2Y₆R), which may contribute to the formation of a tumor-promoting microenvironment by coordinating resistance to apoptosis. Colorectal cancer (CRC) was chemically induced in P2ry6 knockout (P2ry6^-/-) mice using azoxymethane and dextran sulfate sodium challenges. Mice were euthanatized and their tumor load determined. Fixed tissues were stained for histological and immunohistochemistry analysis. Tumoroids were also prepared from CRC tumors resected from P2ry6^+/+ mice to determine the role of P2Y₆R in resistance to apoptosis, whereas HT29 carcinoma cells were used to elucidate the signaling mechanism involved in P2Y₆R anti-apoptotic effect. P2ry6^-/- mice developed a reduced number of colorectal tumors with apparent tumors having smaller volumes. Overall dysplastic score was significantly lower in P2ry6^-/- animals. Stimulation of P2Y₆R with the selective agonist MRS2693 protected HT-29 cells from TNFα-induced apoptosis. This protective effect was mediated by the stabilizing phosphorylation of the X-linked inhibitor of apoptosis protein (XIAP) by AKT. Using CRC-derived tumoroids, P2Y₆R activation was found to contribute to chemoresistance since addition of the P2Y₆R agonist MRS2693 significantly prevented the cytotoxic effect of 5-fluorouracil. The present study shows that sustained activation of P2Y₆R may contribute to intestinal tumorigenesis by blocking the apoptotic process and by contributing to chemoresistance, a substantial concern in the treatment of patients with CRC. These results suggest that P2Y₆R may represent a prime target for reducing colorectal carcinogenesis.

β-Catenin and CD44 Expression in Keratoacanthoma and Squamous Cell Carcinoma of the Skin

CD44 and β-catenin are adhesion molecules expressed on a wide variety of cells. Failure of this expression is believed to lead to disruption of cell-cell adhesion and to neoplasia. The aim of this study was to investigate the staining intensity of CD44 and β-catenin in keratoacanthomas and squamous cell carcinomas of the skin. The proliferation index, PCNA staining, was also evaluated in these cases. The abnormal expression of β-catenin significantly predominated in squamous cell carcinomas (n = 20, 76.9%) compared with keratoacanthomas (P = 0.002, χ2 = 7.8). Most keratoacanthomas (n = 11, 61.1%) more frequently showed strong staining intensity with CD44 compared with squamous cell carcinoma (P = 0.001, χ2 = 13.7). The proliferation index was higher in squamous cell carcinoma (P = 0.000, χ2 = 12.8). These findings suggest that CD44 and β-catenin expression may have an important role in the development of malignancy and in the determination of biological features of keratoacanthoma and squamous cell carcinoma of the skin.

Long non-coding RNA UCA1 contributes to the progression of oral squamous cell carcinoma by regulating the WNT/β-catenin signaling pathway

With the development of functional genomics studies, a mass of long non-coding RNAs (LncRNA) were discovered from the human genome. Long non-coding RNAs serve as pivotal regulators of genes that are able to generate LncRNA-binding protein complexes to modulate a great number of genes. Recently, the LncRNA urothelial carcinoma-associated 1 (UCA1) has been revealed to be dysregulated, which plays a critical role in the development of a few cancers. However, the role of the biology and clinical significance of UCA1 in the tumorigenesis of oral squamous cell carcinoma (OSCC) remain unknown. We found that UCA1 expression levels were upregulated aberrantly in tongue squamous cell carcinoma tissues and associated with lymph node metastasis and TNM stage. We explored the expression, function, and molecular mechanism of LncRNA UCA1 in OSCC. In the present work, we revealed that UCA1 silencing suppressed proliferation and metastasis and induced apoptosis of OSCC cell lines in vitro and in vivo, which might be related to the activation level of the WNT/β-catenin signaling pathway. Our research results emphasize the pivotal role of UCA1 in the oncogenesis of OSCC and reveal a novel LncRNA UCA1-β-catenin-WNT signaling pathway regulatory network that could contribute to our understanding in the pathogenesis of OSCC and assist in the discovery of a viable LncRNA-directed diagnostic and therapeutic strategy for this fatal disease.

Therapeutic aspects of c-MYC signaling in inflammatory and cancerous colonic diseases

Colonic inflammation is required to heal infections, wounds, and maintain tissue homeostasis. As the seventh hallmark of cancer, however, it may affect all phases of tumor development, including tumor initiation, promotion, invasion and metastatic dissemination, and also evasion immune surveillance. Inflammation acts as a cellular stressor and may trigger DNA damage or genetic instability, and, further, chronic inflammation can provoke genetic mutations and epigenetic mechanisms that promote malignant cell transformation. Both sporadical and colitis-associated colorectal carcinogenesis are multi-step, complex processes arising from the uncontrolled proliferation and spreading of malignantly transformed cell clones with the obvious ability to evade the host’s protective immunity. In cells upon DNA damage several proto-oncogenes, including c-MYC are activated in parelell with the inactivation of tumor suppressor genes. The target genes of the c-MYC protein participate in different cellular functions, including cell cycle, survival, protein synthesis, cell adhesion, and micro-RNA expression. The transcriptional program regulated by c-MYC is context dependent, therefore the final cellular response to elevated c-MYC levels may range from increased proliferation to augmented apoptosis. Considering physiological intestinal homeostasis, c-MYC displays a fundamental role in the regulation of cell proliferation and crypt cell number. However, c-MYC gene is frequently deregulated in inflammation, and overexpressed in both sporadic and colitis-associated colon adenocarcinomas. Recent results demonstrated that endogenous c-MYC is essential for efficient induction of p53-dependent apoptosis following DNA damage, but c-MYC function is also involved in and regulated by autophagy-related mechanisms, while its expression is affected by DNA-methylation, or histone acetylation. Molecules directly targeting c-MYC, or agents acting on other genes involved in the c-MYC pathway could be selected for combined regiments. However, due to its context-dependent cellular function, it is clinically essential to consider which cytotoxic drugs are used in combination with c-MYC targeted agents in various tissues. Increasing our knowledge about MYC-dependent pathways might provide direction to novel anti-inflammatory and colorectal cancer therapies.

Role of neutral ceramidase in colon cancer

Alterations in sphingolipid metabolism, especially ceramide and sphingosine 1-phosphate, have been linked to colon cancer, suggesting that enzymes of sphingolipid metabolism may emerge as novel regulators and targets in colon cancer. Neutral ceramidase (nCDase), a key enzyme in sphingolipid metabolism that hydrolyzes ceramide into sphingosine, is highly expressed in the intestine; however, its role in colon cancer has not been defined. Here we show that molecular and pharmacological inhibition of nCDase in colon cancer cells increases ceramide, and this is accompanied by decreased cell survival and increased apoptosis and autophagy, with minimal effects on noncancerous cells. Inhibition of nCDase resulted in loss of β-catenin and inhibition of ERK, components of pathways relevant for colon cancer development. Furthermore, inhibition of nCDase in a xenograft model delayed tumor growth and increased ceramide while decreasing proliferation. It is noteworthy that mice lacking nCDase treated with azoxymethane were protected from tumor formation. Taken together, these studies show that nCDase is pivotal for regulating initiation and development of colon cancer, and these data suggest that this enzyme is a suitable and novel target for colon cancer therapy.-García-Barros, M., Coant, N., Kawamori, T., Wada, M., Snider, A. J., Truman, J.-P., Wu, B. X., Furuya, H., Clarke, C. J., Bialkowska, A. B., Ghaleb, A., Yang, V. W., Obeid, L. M., Hannun, Y. A. Role of neutral ceramidase in colon cancer.

Comparison of biomarker expression between proximal and distal colorectal adenomas: The Tennessee-Indiana Adenoma Recurrence Study

It is unclear if proximal and distal traditional adenomas present with differences in molecular events which contribute to cancer heterogeneity by tumor anatomical subsite. Participants from a colonoscopy-based study (n = 380) were divided into subgroups based on the location of their most advanced adenoma: proximal, distal, or "equivalent both sides." Eight biomarkers in the most advanced adenomas were evaluated by immunohistochemistry (Ki-67, COX-2, TGFβRII, EGFR, β-catenin, cyclin D1, c-Myc) or TUNEL (apoptosis). After an adjustment for pathological features, there were no significant differences between proximal and distal adenomas for any biomarker. Conversely, expression levels did vary by other features, such as their size, villous component, and synchronousness. Large adenomas had higher expression levels of Ki-67(P < 0.001), TGFβRII (P < 0.0001), c-Myc (P < 0.001), and cyclin D1 (P < 0.001) in comparison to small adenomas, and tubulovillous/villous adenomas also were more likely to have similar higher expression levels in comparison to tubular adenomas. Adenoma location is not a major determinant of the expression of these biomarkers outside of other pathological features. This study suggests similarly important roles of Wnt/β-catenin and TGF-β pathways in carcinogenesis in both the proximal and distal colorectum. © 2016 Wiley Periodicals, Inc.

Proteomic characterization of peroxisome proliferator-activated receptor-γ (PPARγ) overexpressing or silenced colorectal cancer cells unveils a novel protein network associated with an aggressive phenotype

Peroxisome proliferator-activated receptor-γ (PPARγ) is a transcription factor of the nuclear hormone receptor superfamily implicated in a wide range of processes, including tumorigenesis. Its role in colorectal cancer (CRC) is still debated; most reports support that PPARγ reduced expression is associated with poor prognosis. We employed 2-Dimensional Differential InGel Electrophoresis (2-D DIGE) followed by Liquid Chromatography (LC)-tandem Mass Spectrometry (MS/MS) to identify differentially expressed proteins and the molecular pathways underlying PPARγ expression in CRC progression. We identified several differentially expressed proteins in HT29 and HCT116 CRC cells and derived clones either silenced or overexpressing PPARγ, respectively. In Ingenuity Pathway Analysis (IPA) they showed reciprocal relation with PPARγ and a strong relationship with networks linked to cell death, growth and survival. Interestingly, five of the identified proteins, ezrin (EZR), isoform C of prelamin-A/C (LMNA), alpha-enolase (ENOA), prohibitin (PHB) and RuvB-like 2 (RUVBL2) were shared by the two cell models with opposite expression levels, suggesting a possible regulation by PPARγ. mRNA and western blot analysis were undertaken to obtain a technical validation and confirm the expression trend observed by 2-D DIGE data. We associated EZR upregulation with increased cell surface localization in PPARγ-overexpressing cells by flow cytometry and immunofluorescence staining. We also correlated EZR and PPARγ expression in our series of CRC specimens and the expression profiling of all five proteins levels in the publicly available colon cancer genomic data from Oncomine and Cancer Genome Atlas (TCGA) colon adenocarcinoma (COAD) datasets. In summary, we identified a panel of proteins correlated with PPARγ expression that could be associated with CRC unveiling new pathways to be investigated for the selection of novel potential prognostic/predictive biomarkers and/or therapeutic targets.

Regulation of β-catenin transcription activity by leupaxin in hepatocellular carcinoma

In human cancers, β-catenin is accumulated in the nucleus and activates mRNA transcription of many oncogenic genes, such as cyclin D1 and c-myc. However, the mechanism of β-catenin-mediated transcriptional activation remains largely unknown. In the present study, we identified leupaxin, an adaptor protein sharing homology with the focal adhesion protein, as a novel coactivator for β-catenin in human hepatocellular carcinoma (HCC). We show that leupaxin could interact with β-catenin and enhance its transcriptional activity through recruitment of coactivator complex, including steroid receptor coactivator 1 (SRC-1) and P300. As a result, leupaxin regulates HCC cell proliferation and cell-cycle progression in the presence of intact Wnt/β-catenin signaling. Furthermore, leupaxin is overexpressed in HCC tissues and correlated with mRNA levels of cyclin D1 and c-myc. Therefore, this is the first demonstration of a role for the leupaxin in the regulation of HCC progression, at least in part, by enhancing β-catenin transcription activity.

OTUB1 promotes metastasis and serves as a marker of poor prognosis in colorectal cancer

Background

OTUB1 (OTU deubiquitinase, ubiquitin aldehyde binding 1) is a deubiquitinating enzyme (DUB) that belongs to the OTU (ovarian tumor) superfamily. The aim of this study was to clarify the role of OTUB1 in colorectal cancer (CRC) and to identify the mechanism underlying its function.

Methods

Two hundred and sixty CRC samples were subjected to association analysis of OTUB1 expression and clinicopathological variables using immunohistochemical (IHC) staining. Overexpression of OTUB1 was achieved in SW480 and DLD-1 cells, and downregulation of OTUB1 was employed in SW620 cells. Then, migration and invasion assays were performed, and markers of the epithelial-mesenchymal transition (EMT) were analyzed. In addition, hepatic metastasis models in mice were used to validate the function of OTUB1 in vivo.

Results

OTUB1 was overexpressed in CRC tissues, and the expression level of OTUB1 was associated with metastasis. A high expression level of OTUB1 was also associated with poor survival, and OTUB1 served as an independent prognostic factor in multivariate analysis. OTUB1 also promoted the metastasis of CRC cell lines in vitro and in vivo by regulating EMT.

Conclusions

OTUB1 promotes CRC metastasis by facilitating EMT and acts as a potential distant metastasis marker and prognostic factor in CRC. Targeting OTUB1 may be helpful for the treatment of CRC.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-258) contains supplementary material, which is available to authorized users.

Identification of suitable reference genes for investigating gene expression in human gallbladder carcinoma using reverse transcription quantitative polymerase chain reaction

Reverse transcription quantitative polymerase chain reaction (RT‑qPCR) has become a frequently used strategy in gene expression studies. The relative quantification method is an important and commonly used method for the evaluation of RT‑qPCR data. The key aim of this method is to identify an applicable internal reference gene, however, there are currently no suitable reference genes for gene analysis in gallbladder carcinoma. In the present study, screening was performed using 12 common reference genes, which were selected in order to provide an experimental basis for the investigation of gene expression in gallbladder carcinoma. A total of 16 tissue samples of gallbladder carcinoma and their matched normal gallbladder tissues were used. The gene expression stability and applicability of the 12 reference gene candidates were determined using the geNorm, NormFinder and BestKeeper software programs. Following comparison of the results of the three software programs, HPRT1 was identified as the most stably expressed reference gene. In the normal gallbladder group, the relative stably expressed reference gene was PPIA and in the entire sample group, the relatively stably expressed reference gene was PPIA. The present study also demonstrated that the combination of the three reference genes was the most appropriate. The recommended combinations were PPIA + PUM1 + ACTB for the total sample group, GAPDH + PBGD + ALAS1 for the gallbladder carcinoma group and PPIA + PUM1 + TBP for the paired normal gallbladder group.

Wnt secretion is required to maintain high levels of Wnt activity in colon cancer cells

Aberrant regulation of the Wnt/β-catenin pathway has an important role during the onset and progression of colorectal cancer, with over 90% of cases of sporadic colon cancer featuring mutations in APC or β-catenin. However, it has remained a point of controversy whether these mutations are sufficient to activate the pathway or require additional upstream signals. Here we show that colorectal tumours express elevated levels of Wnt3 and Evi/Wls/GPR177. We found that in colon cancer cells, even in the presence of mutations in APC or β-catenin, downstream signalling remains responsive to Wnt ligands and receptor proximal signalling. Furthermore, we demonstrate that truncated APC proteins bind β-catenin and key components of the destruction complex. These results indicate that cells with mutations in APC or β-catenin depend on Wnt ligands and their secretion for a sufficient level of β-catenin signalling, which potentially opens new avenues for therapeutic interventions by targeting Wnt secretion via Evi/Wls.

Activating mutations in the Wnt signalling pathway are associated with colon cancer. Here the authors show that tumour cells carrying mutations in APC and β-catenin are still regulated by Wnt ligands, suggesting that Wnt secretion and receptor signalling remains important to control downstream signalling.

Frizzled10 mediates WNT1 and WNT3A signaling in the dorsal spinal cord of the developing chick embryo

BACKGROUND

WNT1 and WNT3A drive a dorsal to ventral gradient of β-catenin-dependent Wnt signaling in the developing spinal cord. However, the identity of the receptors mediating downstream functions remains poorly understood.

RESULTS

In this report, we show that the spatiotemporal expression patterns of FZD10 and WNT1/WNT3A are highly correlated. We further show that in the presence of LRP6, FZD10 promotes WNT1 and WNT3A signaling using an 8xSuperTopFlash reporter assay. Consistent with a functional role for FZD10, we demonstrate that FZD10 is required for proliferation in the spinal cord. Finally, by using an in situ proximity ligation assay, we observe an interaction between FZD10 and WNT1 and WNT3A proteins.

CONCLUSIONS

Together, our results identify FZD10 as a receptor for WNT1 and WNT3A in the developing chick spinal cord.

Expression of RUNX3 and β-catenin in the carcinogenesis of sporadic colorectal tubular adenoma

The aim of this study is to investigate the possible roles of runt-related transcription factor 3 (RUNX3) and β-catenin in the carcinogenesis of sporadic colorectal tubular adenomas. The expression of the RUNX3 and β-catenin proteins was evaluated by immunohistochemistry in 23 normal colorectal mucosa (NCM), 81 sporadic colorectal tubular adenomas with different dysplasias (SCTA-D) (mild n=33, moderate n=23, and severe n=25 dysplasia), and 48 sporadic colorectal tubular adenomas with cancerous changes (SCTA-Ca). RUNX3 methylation was assessed by methylation-specific polymerase chain reaction (MSP), combined with laser capture microdissection (LCM), in 17 NCM, 41 SCTA-D (mild n=15, moderate n=12, and severe n=14 dysplasia), and 17 SCTA-Ca tissues. Compared to NCM (82.6 %), RUNX3 in SCTA-D (54.3 %) and SCTA-Ca (27.1 %) was significantly downregulated (P<0.05). In NCM, SCTA-D, and SCTA-Ca, the incidence of positive expression for β-catenin was 13.0, 60.5, and 79.2 %, respectively. A statistically significant difference was observed (P<0.05). RUNX3 levels were markedly higher in adenoma with mild dysplasia (75.8 %) and moderate dysplasia (60.9 %) than in adenoma with severe dysplasia (20.0 %) (both with P<0.05). Likewise, the expression of β-catenin in severe dysplasia adenoma was 84.0 %, which was significantly higher than that in mild dysplasia adenoma (39.4 %). An inverse correlation was found between the protein expression of RUNX3 and β-catenin in SCTA-D and SCTA-Ca (P<0.05). MSP results showed that RUNX3 methylation in NCM, SCTA-D, and SCTA-Ca was 5.9, 17.1, and 41.2 %, respectively, with a statistically significant difference between NCM and SCTA-Ca (P<0.05). However, no significant difference of RUNX3 methylation was observed among different dysplasia groups. RUNX3 and β-catenin play important roles in the carcinogenesis of sporadic colorectal tubular adenomas. In addition, hypermethylation of RUNX3 can downregulate its expression.

Androgen activates β-catenin signaling in bladder cancer cells

Androgen receptor (AR) signals have been implicated in bladder carcinogenesis and tumor progression. Activation of Wnt/β-catenin signaling has also been reported to correlate with bladder cancer progression and poor patients' outcomes. However, cross talk between AR and β-catenin pathways in bladder cancer remains uncharacterized. In radical cystectomy specimens, we immunohistochemically confirmed aberrant expression of β-catenin especially in aggressive tumors. There was a strong association between nuclear expressions of AR and β-catenin in bladder tumors (P=0.0215). Kaplan-Meier and log-rank tests further revealed that reduced membranous β-catenin expression (P=0.0276), nuclear β-catenin expression (P=0.0802), and co-expression of nuclear AR and β-catenin (P=0.0043) correlated with tumor progression after cystectomy. We then assessed the effects of androgen on β-catenin in AR-positive and AR-negative bladder cancer cell lines. A synthetic androgen R1881 increased the expression of an active form of β-catenin and its downstream target c-myc only in AR-positive lines. R1881 also enhanced the activity of β-catenin-mediated transcription, which was abolished by an AR antagonist hydroxyflutamide. Using western blotting and immunofluorescence, R1881 was found to induce nuclear translocation of β-catenin when co-localized with AR. Finally, co-immunoprecipitation revealed androgen-induced associations of AR with β-catenin or T-cell factor (TCF) in bladder cancer cells. Thus, it was likely that androgen was able to activate β-catenin signaling through the AR pathway in bladder cancer cells. Our results also suggest that activation of β-catenin signaling possibly via formation of AR/β-catenin/TCF complex contributes to the progression of bladder cancer, which may enhance the feasibility of androgen deprivation as a potential therapeutic approach.

Beta-catenin expression in pilomatrix carcinoma with multiple visceral metastases in a dog

Beta-catenin is a protein initially identified as a submembrane component of the E-cadherin-mediated cell-to-cell adhesion system. It plays a role as a transcriptional factor in the wingless/Wnt signalling pathway. Beta-catenin has been associated with oncogenic activity in human benign and malignant pilomatrix neoplasms where the immunohistochemical profile of β-catenin expression displayed both nuclear and cytoplasmic staining in basaloid cells. In this study, an 8-year-old female Irish setter dog was examined because of the presence of skin nodules. Tissue biopsies from different nodules were obtained and histological examination suggested a diagnosis of pilomatrix carcinoma. The dog spontaneously died after 2 months and necropsy showed multiple metastases in the nasal cavity, lungs, heart, kidney, liver and colon. Routine histopathology of metastatic sites showed features consistent with the pattern of primary neoplastic nodules. Immunohistochemical detection of β-catenin was performed in both the primary tumour and the metastases. Beta-catenin expression was located in the nuclei, cytoplasm and membrane of squamoid cells and in the cytoplasm of basaloid cells, while shadow cells were completely negative. To the best of our knowledge, these data represent the first report on the immunohistochemical expression profile of β-catenin in canine pilomatrix carcinoma.

Transforming growth factor-β 1 enhances the invasiveness of breast cancer cells by inducing a Smad2-dependent epithelial-to-mesenchymal transition

Metastasis is unequivocally the most lethal aspect of breast cancer and the most prominent feature associated with disease recurrence, the molecular mechanisms whereby epithelial-to-mesenchymal transition (EMT) mediates the initiation and resolution of breast cancer metastasis remains poorly understood. Transforming growth factor-β1 (TGF-β1) is a multifunctional cytokine that is intimately involved in regulating numerous physiological processes, including cellular differentiation, homeostasis and EMT. Recent findings have implicated high levels of TGF-β1 were associated with poor outcome, whereas inhibition of TGF-β signaling reduces metastasis in breast cancer, suggesting that the chemo-therapeutic targeting of TGF-β1 or TGF-β signaling may offer new inroads in ameliorating metastatic disease in breast cancer patients. In this study, we showed immunohistochemical evidence for EMT, which is associated with TGF-β1 expression, at the invasion front of breast cancer in vivo. The data also indicated that human breast cancer cell lines, MCF-7 and MDA-MB-435S, of epithelial cell characteristics were induced to undergo EMT by TGF-β1 and dependent on the Smad2 signaling pathway. Following TGF-β1 treatment, cells showed dramatic morphological changes assessed by phase contrast microscopy, accompanied by decreased epithelial marker and increased mesenchymal markers. Importantly, cell invasion was also enhanced in the EMT process, while knockdown of the Smad2 gene by silencing siRNA partially inhibited these effects in MDA-MB435S (P<0.05). These data suggested that EMT of breast cancer induced by TGF-β1 is dependent on Smad2 signaling and promotes breast cancer cell metastasis.

MicroRNA-200a suppresses the Wnt/β-catenin signaling pathway by interacting with β-catenin

The Wnt/β-catenin signaling pathway is crucial for human organ development and is involved in tumor progression of many cancers. Accumulating evidence suggests that the expression of β-catenin is, in part, regulated by specific microRNAs (miRNAs). The purpose of this study was to determine the expression of a recently identified epithelial to mesenchymal transition (EMT)-associated tumor suppressor microRNA (miR)-200a, in cancer cells. We also aimed to identify specific miR-200a target genes and to investigate the antitumor effects of miR-200a on the Wnt/β-catenin signaling pathway. We employed TOP/FOP flash luciferase assays to identify the effect of miR-200a on the Wnt/β-catenin pathway and we confirmed our observations using fluorescence microscopy. To determine target genes of miR-200a, a 3' untranslated region (3' UTR) luciferase assay was performed. Cell viability, invasion and wound healing assays were carried out for functional analysis after miRNA transfection. We further investigated the role of miR-200a in EMT by Western blot analysis. We found fluctuation in the expression of miR-200a that was accompanied by changes in the expression of members of the Wnt/β-catenin signaling pathway. We also determined that miR-200a can directly interact with the 3' UTR of CTNNB1 (the gene that encodes β-catenin) to suppress Wnt/β-catenin signaling. MiR-200a could also influence the biological activities of SGC790 and U251 cells. Our results demonstrate that miR-200a is a new tumor suppressor that can regulate the activity of the Wnt/β-catenin signaling pathway via two mechanisms. MiR-200a is a candidate target for tumor treatment via its regulation of the Wnt/β-catenin signaling pathway.

MicroRNA-200a suppresses the Wnt/β-catenin signaling pathway by interacting with β-catenin

The Wnt/β-catenin signaling pathway is crucial for human organ development and is involved in tumor progression of many cancers. Accumulating evidence suggests that the expression of β-catenin is, in part, regulated by specific microRNAs (miRNAs). The purpose of this study was to determine the expression of a recently identified epithelial to mesenchymal transition (EMT)-associated tumor suppressor microRNA (miR)-200a, in cancer cells. We also aimed to identify specific miR-200a target genes and to investigate the antitumor effects of miR-200a on the Wnt/β-catenin signaling pathway. We employed TOP/FOP flash luciferase assays to identify the effect of miR-200a on the Wnt/β-catenin pathway and we confirmed our observations using fluorescence microscopy. To determine target genes of miR-200a, a 3' untranslated region (3' UTR) luciferase assay was performed. Cell viability, invasion and wound healing assays were carried out for functional analysis after miRNA transfection. We further investigated the role of miR-200a in EMT by Western blot analysis. We found fluctuation in the expression of miR-200a that was accompanied by changes in the expression of members of the Wnt/β-catenin signaling pathway. We also determined that miR-200a can directly interact with the 3' UTR of CTNNB1 (the gene that encodes β-catenin) to suppress Wnt/β-catenin signaling. MiR-200a could also influence the biological activities of SGC790 and U251 cells. Our results demonstrate that miR-200a is a new tumor suppressor that can regulate the activity of the Wnt/β-catenin signaling pathway via two mechanisms. MiR-200a is a candidate target for tumor treatment via its regulation of the Wnt/β-catenin signaling pathway.

The expression pattern of aldehyde dehydrogenase 1 (ALDH1) is an independent prognostic marker for low survival in colorectal tumors

BACKGROUND

Aldehyde dehydrogenase-1 (ALDH1) is involved in the regulation of cell proliferation and differentiation. Moreover, it is a marker for cancer stem cells (CSC). As CSCs were shown to be the driving force of tumor progression and metastases we suspected that the expression of ALDH1 correlated with the prognostic 5 year survival of colorectal cancer.

METHODS

ALDH1 expression was analyzed in a highly stratified collective of 186 T3 N0 M0 G2 primary colorectal cancer specimens applying immunohistochemistry. For the analysis a scoring system for the expression of ALDH1 was developed that was aided by the pattern of the subcellular expression of beta-catenin which is a well known indicator for colorectal CSCs.

RESULTS

First, ALDH1 expression could be assigned to two groups which correlated with the absence or presence of nuclear beta-catenin expression. Second, ALDH1 group 2 expression patterning correlated highly significantly with low long term survival (p=0.010) of patients with T3 N0 M0 G2 colorectal cancer. This correlation was found univariately and when applying the multivariate Cox-model.

CONCLUSION

ALDH1 expression pattern is an independent prognostic marker for survival of T3 N0 M0 G2 colorectal cancer patients.

β-catenin tyrosine 654 phosphorylation increases Wnt signalling and intestinal tumorigenesis

Objective Deregulation of the Wnt signalling pathway by mutations in the Apc or β-catenin genes underlies colorectal carcinogenesis. As a result, β-catenin stabilises, translocates to the nucleus, and activates gene transcription. Intestinal tumours show a heterogeneous pattern of nuclear β-catenin, with the highest levels observed at the invasion front. Activation of receptor tyrosine kinases in these tumour areas by growth factors expressed by surrounding stromal cells phosphorylate β-catenin at tyrosine residues, which is thought to increase β-catenin nuclear translocation and tumour invasiveness. This study investigates the relevance of β-catenin tyrosine phosphorylation for Wnt signalling and intestinal tumorigenesis in vivo. Design A conditional knock-in mouse model was generated into which the phospho-mimicking Y654E modification in the endogenous β-catenin gene was introduced. Results This study provided in vivo evidence that β-catenin(E654) is characterised by reduced affinity for cadherins, increased signalling and strongly increased phosphorylation at serine 675 by protein kinase A (PKA). In addition, homozygosity for the β-catenin(E654) targeted allele caused embryonic lethality, whereas heterozygosity predisposed to intestinal tumour development, and strongly enhanced Apc-driven intestinal tumour initiation associated with increased nuclear accumulation of βcatenin. Surprisingly, the expression of β-catenin(E654) did not affect histological grade or induce tumour invasiveness. Conclusions A thus far unknown mechanism was uncovered in which Y654 phosphorylation of β-catenin facilitates additional phosphorylation at serine 675 by PKA. In addition, in contrast to the current belief that β-catenin Y654 phosphorylation increases tumour progression to a more invasive phenotype, these results show that it rather increases tumour initiation by enhancing Wnt signalling.

Colorectal cancers choosing sides

In contrast to the majority of sporadic colorectal cancer which predominantly occur in the distal colon, most mismatch repair deficient tumours arise at the proximal side. At present, these regional preferences have not been explained properly. Recently, we have screened colorectal tumours for mutations in Wnt-related genes focusing specifically on colorectal location. Combining this analysis with published data, we propose a mechanism underlying the side-related preferences of colorectal cancers, based on the specific acquired genetic defects in β-catenin signalling.

The elements of human cyclin D1 promoter and regulation involved

Cyclin D1 is a cell cycle machine, a sensor of extracellular signals and plays an important role in G1-S phase progression. The human cyclin D1 promoter contains multiple transcription factor binding sites such as AP-1, NF-қB, E2F, Oct-1, and so on. The extracellular signals functions through the signal transduction pathways converging at the binding sites to active or inhibit the promoter activity and regulate the cell cycle progression. Different signal transduction pathways regulate the promoter at different time to get the correct cell cycle switch. Disorder regulation or special extracellular stimuli can result in cell cycle out of control through the promoter activity regulation. Epigenetic modifications such as DNA methylation and histone acetylation may involved in cyclin D1 transcriptional regulation.

Detection of β-catenin, gastrokine-2 and embryonic stem cell expressed ras in gastric cancers

ERas activation and GKN2 reduction in gastric cancer has raised some notices in recent years, while nuclear beta-catenin positivity is considered as a tumoral marker. In this study, we compared immunohistochemistry of beta-catenin, GKN2 and ERas on tumoral and non-tumoral mucosae of 50 gastric carcinomas and 13 gastric samples of cancer-free patients. Nuclear positivity of beta-catenin was strong in 31 non-tumoral mucosae (62%) and 29 tumoral mucosae (58%). It was absent in samples of cancer-free patients. There was a correlation between non-tumoral and tumoral zones for nuclear beta-catenin positivity (P=0.013). ERas was positive in 35 non-tumoral tissues (70%) and 31 tumoral tissues (62%) but negatvie in samples of cancer-free patients. It was weak and spotty in non-tumoral mucosae but strong and diffuse in tumors. Positivity of ERas was age-related (P=0.028). However it had background staining effect. GKN2 was expressed in 33 non-tumoral mucosae (66%) and 35 tumoral mucosae (70%). Though GKN2 staining was moderate to strong in non-tumoral tissues and was comparatively weaker in tumors, their difference was minimal and difficult to discern.

CONCLUSIONS

Beta-catenin nuclear location could be considered as a paraneoplastic pattern which is considerably tumor-related. ERas may be a potential biomarker for gastric cancer, but advanced studies are wanted. GKN2 reduction is indiscernible by immunostaining.

Loss of myeloid cell-derived vascular endothelial growth factor accelerates fibrosis

Tissue injury initiates a complex series of events that act to restore structure and physiological homeostasis. Infiltration of inflammatory cells and vascular remodeling are both keystones of this process. However, the role of inflammation and angiogenesis in general and, more specifically, the significance of inflammatory cell-derived VEGF in this context are unclear. To determine the role of inflammatory cell-derived VEGF in a clinically relevant and chronically inflamed injury, pulmonary fibrosis, we deleted the VEGF-A gene in myeloid cells. In a model of pulmonary fibrosis in mice, deletion of VEGF in myeloid cells resulted in significantly reduced formation of blood vessels; however, it causes aggravated fibrotic tissue damage. This was accompanied by a pronounced decrease in epithelial cell survival and a striking increase in myofibroblast invasion. The drastic increase in fibrosis following loss of myeloid VEGF in the damaged lungs was also marked by increased levels of hypoxia-inducible factor (HIF) expression and Wnt/beta-catenin signaling. This demonstrates that the process of angiogenesis, driven by myeloid cell-derived VEGF, is essential for the prevention of fibrotic damage.

Gastrointestinal stem cells in development and cancer

An enormous body of knowledge about the biology of stem cells and their role in development, tissue homeostasis and cancer formation has been gained in the last 20 years. This review gives a comprehensive overview on knowledge about localization and regulation of normal gastrointestinal stem cells and links it to our understanding of gastrointestinal tumourigenesis and malignant progression in the light of the cancer stem cell concept. The focus is on intestinal stem cells and newly identified stem cell factors, such as the beta-catenin target gene Lgr5. The basis of intestinal stem cell regulation is a permanent crosstalk between epithelial and underlying mesenchymal cells in the intestinal stem cell niche. This crosstalk is mediated by crucial pathways, including the Wnt, Hedgehog (HH), Notch, PI3K and BMP pathways. Disturbances in this fine-regulated interaction can both initiate intestinal tumours and, in association with additional genetic alterations or environmental activation of embryonic processes such as epithelial-mesenchymal transition (EMT), lead to tumour invasion and metastasis.

Epithelial morphogenesis and intestinal cancer: new insights in signaling mechanisms

In this review, the major signal transduction pathways that have been shown to play an important role in intestinal homeostasis are highlighted. Each of them, the Wnt, Notch, Hedgehog, and Bone Morphogenetic Protein, as well as growth-factor regulated Receptor Tyrosine Kinases are depicted with a special emphasis through their involvement in stem cell maintenance and their role in intestinal tumorigenesis. Finally, we discuss recent data on the final steps of tumor progression, notably the formation of distant metastases. This multistep process is highly complex and still far from being understood while being of major importance for the survival of patients with digestive cancer.

Chemoprevention by white currant is mediated by the reduction of nuclear beta-catenin and NF-kappaB levels in Min mice adenomas

BACKGROUND

Berries are a good natural source of phenolic compounds and many berries or their compounds have been shown to be chemopreventive. White currant is an interesting berry, as it contains low levels of dominant berry phenolics such as ellagic acid, anthocyanins and other flavonoids.

AIMS OF THE STUDY

To study if white currant is chemopreventive in an experimental model for intestinal tumorigenesis and further study the effects on beta-catenin and NF-kappaB signaling pathways.

METHODS

Multiple intestinal neoplasia (Min) mice were fed an AIN-93G based control diet or a diet containing 10% freeze dried white currant (Ribes x pallidum) for 10 weeks. Cell signaling parameters were analysed from intestinal adenomas and surrounding mucosa by Western blotting and immunohistochemistry.

RESULTS

The white currant diet reduced the number of adenomas from 81 (min-max 47-114) to 51 (36-84) in the total small intestine of Min mice (P<0.02). Most of the adenomas develop in the distal part of the small intestine, and in this area white currant reduced the number from 49 to 29.5 (P<0.01) and also the size of the adenomas from 0.88 mm to 0.70 mm (P<0.02). In the colon white currant increased the number of adenomas (0.3+/-0.6 vs. 0.8+/-0.6, mean +/- SD, P<0.05), but did not affect the size. White currant reduced nuclear beta-catenin and NF-kappaB protein levels in the adenomas (P<0.05 and P<0.02, respectively). They were correlated with the size of adenomas (P<0.01).

CONCLUSIONS

This study shows that white currant is effective in preventing cancer initiation and progression in the Min mouse. Whether the positive effects are due to its special phenolic composition needs to be studied in more detail.

Crosstalk between tumor cells and microenvironment via Wnt pathway in colorectal cancer dissemination

Invasion and metastasis are the deadly face of malignant tumors. Considering the high rate of incidence and mortality of colorectal cancer, it is critical to determine the mechanisms of its dissemination. In the parallel investigation of the invasive front and tumor center area of colorectal cancer (CRC), observation of heterogeneous β-catenin distribution and epithelial-mesenchymal transition (EMT) at the invasive front suggested that there might be a crosstalk between tumor cells and the tumor microenvironment. Wnt signaling pathway is also involved in the cancer progression due to its key role in CRC tumorigenesis. Moreover, in recent years, there is increasing evidence that the regulators of microenvironment, including extracellular matrix, growth factors and inflammatory factors, are associated with the activation of Wnt pathway and the mobility of tumor cells. In this review, we will try to explain how these molecules trigger metastasis via the Wnt pathway.

In vivo and in vitro evidence for transforming growth factor-beta1-mediated epithelial to mesenchymal transition in esophageal adenocarcinoma

There is increasing evidence that epithelial to mesenchymal transition (EMT) is involved in cancer progression. Because local invasion and metastasis occurs early in the pathogenesis of esophageal adenocarcinoma, we hypothesized that EMT may be important in this disease. Using immunohistochemistry in a well-characterized set of adenocarcinoma tissues, we showed down-regulation of epithelial markers (E-cadherin and cytokeratin 18) and up-regulation of mesenchymal markers (vimentin and alpha-smooth muscle actin) with concomitant transforming growth factor-beta1 (TGF-beta1) expression at the invasive margin compared with the central tumor. A panel of esophageal cell lines was examined for the ability of TGF-beta1 to induce EMT in vitro. TE7 cells were selected as a model because TGF-beta1 (0-5 ng/mL) treatment induced morphologic and molecular expression changes suggestive of EMT. In TE7 cells, these TGF-beta1-induced changes were reversed by 100 ng/mL of bone morphogenetic protein 7 (BMP7), another member of the TGF-beta1 superfamily. EMT was mediated via canonical TGF-beta1 signaling with concomitant up-regulation of SMAD-interacting protein 1. Alterations in functional variables (aggregation, wounding, motility, and invasion) following TGF-beta1 treatment were consistent with a more invasive phenotype. These functional changes were reversed by BMP7 and SMAD4 RNA interference in vitro. These data suggest that TGF-beta1-mediated EMT may be relevant in esophageal carcinogenesis.

Inulin results in increased levels of beta-catenin and cyclin D1 as the adenomas increase in size from small to large in the Min/+ mouse

The mechanism that drives the growth of some colonic adenomas towards malignancy, while permitting others to remain for decades in quiescence, remains unknown. Diets can alter the growth rate of intestinal tumours but it is still unknown whether diets are able to alter the molecular biology of these adenomas in a way that predicts further outcome. To address this issue we fed Min/+ mice with two diets known to lead to different adenoma outcomes: a high-fat control diet (n 15) or a high-fat inulin-enriched (10 % w/w) diet (n 13). To study the effect of diet on cell signalling during adenoma growth, the adenomas of each Min/+ mouse were divided into three size-categories, and the levels of beta-catenin, E-cadherin, cyclin D1 and matrix metalloproteinase-9, which are known to be involved in colon tumorigenesis, were determined. The growth-promoting inulin diet resulted in more large adenomas than the control feeding (P = 0.003) and doubled the total area of the adenomas (P = 0.008). The inulin diet increased the expression of nuclear beta-catenin (P = 0.004) and its target cyclin D1 (P = 0.017) as the adenomas increased in size from small to large, indicating the presence of an accelerated cancerous process. Neither phenomenon was seen in the control group during adenoma growth. Our results suggest that in addition to the number, size, and growth rate of adenomatous polyps, the signalling pattern of the adenomas should also be considered when evaluating preventive dietary strategies.