FRAT1 overexpression leads to aberrant activation of beta-catenin/TCF pathway in esophageal squamous cell carcinoma

Comparative Serum Proteome Profiling of Canine Benign Prostatic Hyperplasia before and after Castration

BPH is the most prevalent prostatic condition in aging dogs. Nevertheless, clinical diagnosis and management remain inconsistent. This study employed in-solution digestion coupled with nano-liquid chromatography tandem mass spectrometry to assess serum proteome profiling of dogs with BPH and those dogs after castration. Male dogs were divided into two groups; control and BPH groups. In the BPH group, each dog was evaluated at two time points: Day 0 (BF subgroup) and Day 30 after castration (AT subgroup). In the BF subgroup, three proteins were significantly upregulated and associated with dihydrotestosterone: solute carrier family 5 member 5, tyrosine-protein kinase, and FRAT regulator of WNT signaling pathway 1. Additionally, the overexpression of polymeric immunoglobulin receptors in the BF subgroup hints at its potential as a novel protein linked to the BPH development process. Conversely, alpha-1-B glycoprotein (A1BG) displayed significant downregulation in the BF subgroup, suggesting A1BG's potential as a predictive protein for canine BPH. Finasteride was associated with increased proteins in the AT subgroup, including apolipoprotein C-I, apolipoprotein E, apolipoprotein A-II, TAO kinase 1, DnaJ homolog subfamily C member 16, PH domain and leucine-rich repeat protein phosphatase 1, neuregulin 1, and pseudopodium enriched atypical kinase 1. In conclusion, this pilot study highlighted alterations in various serum proteins in canine BPH, reflecting different pathological changes occurring in this condition. These proteins could be a source of potential non-invasive biomarkers for diagnosing this disease.

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.

Overexpression of FRAT1 protein is closely related to triple-negative breast cancer

Purpose

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with a poor prognosis and a lack of targeted therapy. Overexpression of FRAT1 is thought to be associated with this aggressive subtype of cancer. Here, we performed a comprehensive analysis and assessed the association between overexpression of FRAT1 and TNBC.

Methods

First, using different web-based bioinformatics platforms (TIMER 2.0, UALCAN, and GEPIA 2), the expression of FRAT1 was assessed. Then, the expression of the FRAT1 protein and hormone receptors and HER2 status were assessed by immunohistochemical analysis. For samples of tumors with equivocal immunoreactivity, we performed silver in situ hybridization of the HER2 gene to determine an accurate HER2 status. Next, we used the R package and bc-GenExMiner 4.8 to analyze the relationship between FRAT1 expression and clinicopathological parameters in breast cancer patients. Finally, we determined the relationship between FRAT1 overexpression and prognosis in patients.

Results

The expression of FRAT1 in breast cancer tissues is significantly higher than in normal tissue. FRAT1 expression was significantly related to worse overall survival (P < 0.05) and was correlated with these clinicopathological features: T stage, N stage, age, high histologic grade, estrogen receptor status, progesterone receptor status, Her-2 status, TNBC status, basal-like status, CK5/6 status, and Ki67 status.

Conclusion

FRAT1 was overexpressed in breast cancer compared to normal tissue, and it may be involved in the progression of breast cancer malignancy. This study provides suggestive evidence of the prognostic role of FRAT1 in breast cancer and the therapeutic target for TNBC.

FRAT1 promotes the angiogenic properties of human glioblastoma cells via VEGFA

Glioblastoma is a common central nervous system tumor and despite considerable advancements in treatment patient prognosis remains poor. Angiogenesis is a significant prognostic factor in glioblastoma, anti‑angiogenic treatments represent a promising therapeutic approach. Vascular endothelial growth factor A (VEGFA) is a predominant regulator of angiogenesis and mounting evidence suggests that the Wnt signaling pathway serves a significant role in tumor angiogenesis. As a positive regulator of the Wnt/β‑catenin signaling pathway, frequently rearranged in advanced T‑cell lymphomas‑1 (FRAT1) is highly expressed in human glioblastoma and is significantly associated with glioblastoma growth, invasion and migration, as well as poor patient prognosis. Bioinformatics analysis demonstrated that both VEGFA and FRAT1 were highly expressed in most tumor tissues and associated with prognosis. However, whether and how FRAT1 is involved in angiogenesis remains to be elucidated. In the present study, the relationship between FRAT1 and VEGFA in angiogenesis was investigated using the human glioblastoma U251 cell line. Small interfering RNAs (siRNAs) were used to silence FRAT1 expression in U251 cells, and the mRNA and protein expression levels of VEGFA, as well as the concentration of VEGFA in U251 cell supernatants, were determined using reverse transcription‑quantitative PCR, western blotting and ELISA. A tube formation assay was conducted to assess angiogenesis. The results demonstrated that siRNA knockdown significantly decreased the protein expression levels of FRAT1 in U251 cells and markedly decreased the mRNA and protein expression levels of VEGFA. Furthermore, the concentration of VEGFA in the cell supernatant was significantly reduced and angiogenesis was suppressed. These results suggested that FRAT1 may promote VEGFA secretion and angiogenesis in human glioblastoma cells via the Wnt/β‑catenin signaling pathway, supporting the potential use of FRAT1 as a promising therapeutic target in human glioblastoma.

Mechanistic role of DANCR in the choreography of signaling pathways in different cancers: Spotlight on regulation of Wnt/β-catenin and JAK/STAT pathways by oncogenic long non-coding RNA

Discovery of non-coding RNAs has paradigmatically shifted our understanding of the multifaceted nature of cancer. It is becoming progressively more understandable that long non-coding RNAs play fundamental role in regulation of cell signaling pathways in different cancers. DANCR has started to gain remarkable appreciation because of its central role in cancer onset and progression. In this review we have attempted to summarize emerging aspects of DANCR-mediated regulation of Wnt/β-catenin and JAK/STAT pathways in different cancers. We have also discussed how DANCR epigenetically inactivated tumor suppressors to promote cancer. There is sufficient experimental evidence related to oncogenic role of DANCR in variety of cancers. However, there is a need to uncover how DANCR modulates various other oncogenic pathways in different cancers.

Swertiamarin suppresses proliferation, migration, and invasion of hepatocellular carcinoma cells <em>via</em> negative regulation of FRAT1

Studies have shown that swertiamarin (STM) has multiple biological activities, but its anti-tumour effects and molecular mechanisms are still unclear. The present research aimed to validate the STM's impacts on the proliferation, migration, and invasion of hepatocellular carcinoma (HCC) cells, and to study its potential mechanism. Two HCC cell lines were treated with STM. Tumour growth was observed by the mouse tumour xenografts model. HCC cell lines stably expressing T-cell lymphomas 1 (FRAT1) were generated by lentivirusmediated overexpression. Cell viability, proliferation, migration, and invasion were observed using Cell Counting Kit-8 (CCK8), the xCELLigence Real-Time Cell Analyzer system (RTCA), and transwell analysis, respectively. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting were used to observe the expression of FRAT1 and proteins related to the Wnt/β-catenin signalling pathway. Tumour growth was inhibited by STM in vivo. STM suppressed the proliferation, migration, and invasion of HCC cells. STM negatively regulated FRAT1 expression, whereas overexpressed FRAT1 blocked the anti-tumour function of STM. The results revealed that STM suppressed the FRAT1/Wnt/β-catenin signalling pathway. The findings of this study provide new insights into investigation of therapeutic strategies against HCC.

Long non-coding RNA DANCR promotes cervical cancer growth via activation of the Wnt/β-catenin signaling pathway

Background

Long non-coding RNAs (lncRNAs) are implicated in many pathophysiological processes, including cancers. In particular, lncRNA DANCR is regarded as a cancer-associated lncRNA exerting various regulatory mechanisms. However, the expressions, functions, and mechanisms of action of DANCR in cervical cancer are still unclear.

Methods

The expressions of DANCR in cervical cancer tissues and cell lines were evaluated using qRT-PCR. Correlations between DANCR expression and clinicopathological features and prognosis were analyzed. The roles of DANCR in cervical cancer growth were evaluated by in vitro CCK-8 and EdU assay, and in vivo xenograft assay. The regulatory effects of DANCR on Wnt/β-catenin signaling pathway were evaluated using nuclear proteins extraction, western blot, and qRT-PCR.

Results

DANCR is increased in cervical cancer tissues and cell lines. Increased expression of DANCR is associated with large tumor size, advanced FIGO stage, and poor overall survival of cervical cancer patients. Functional experiments showed that enhanced expression of DANCR promotes cervical cancer cell proliferation in vitro and xenograft growth in vivo. Conversely, DANCR knockdown inhibits cervical cancer cell proliferation in vitro and xenograft growth in vivo. Mechanistic investigation demonstrated that DANCR upregulates the expressions of FRAT1 and FRAT2 and activates the Wnt/β-catenin signaling pathway. Blocking the Wnt/β-catenin signaling pathway abolishes the pro-proliferative roles of DANCR overexpression and anti-proliferative roles of DANCR knockdown.

Conclusions

Our findings suggest DANCR as an oncogenic lncRNA in cervical cancer through activating the Wnt/β-catenin signaling pathway, and imply that DANCR may be a promising prognostic biomarker and therapeutic target for cervical cancer.

TMEM98 is a negative regulator of FRAT mediated Wnt/ß-catenin signalling

Wnt/ß-catenin signalling is crucial for maintaining the balance between cell proliferation and differentiation, both during tissue morphogenesis and in tissue maintenance throughout postnatal life. Whereas the signalling activities of the core Wnt/ß-catenin pathway components are understood in great detail, far less is known about the precise role and regulation of the many different modulators of Wnt/ß-catenin signalling that have been identified to date. Here we describe TMEM98, a putative transmembrane protein of unknown function, as an interaction partner and regulator of the GSK3-binding protein FRAT2. We show that TMEM98 reduces FRAT2 protein levels and, accordingly, inhibits the FRAT2-mediated induction of ß-catenin/TCF signalling. We also characterize the intracellular trafficking of TMEM98 in more detail and show that it is recycled between the plasma membrane and the Golgi. Together, our findings not only reveal a new layer of regulation for Wnt/ß-catenin signalling, but also a new biological activity for TMEM98.

Inhibition of miR‑194 suppresses the Wnt/β‑catenin signalling pathway in gastric cancer

A mounting body of evidence has revealed that microRNAs (miRs) serve pivotal roles in various developmental processes, and in tumourigenesis, by binding to target genes and subsequently regulating gene expression. Continued activation of the Wnt/β-catenin signalling is positively associated with human malignancy. In addition, miR-194 dysregulation has been implicated in gastric cancer (GC); however, the molecular mechanisms underlying the effects of miR-194 on GC carcinogenesis remain to be elucidated. The present study demonstrated that miR-194 was upregulated in GC tissues and SUFU negative regulator of Ηedgehog signaling (SUFU) was downregulated in GC cell lines. Subsequently, inhibition of miR-194 attenuated nuclear accumulation of β-catenin, which consequently blocked Wnt/β-catenin signalling. In addition, the cytoplasmic translocation of β-catenin induced by miR-194 inhibition was mediated by SUFU. Furthermore, genes associated with the Wnt/β-catenin signalling pathway were revealed to be downregulated following inhibition of the Wnt signalling pathway by miR-194 suppression. Finally, the results indicated that cell apoptosis was markedly increased in response to miR-194 inhibition, strongly suggesting the carcinogenic effects of miR-194 in GC. Taken together, these findings demonstrated that miR-194 may promote gastric carcinogenesis through activation of the Wnt/β-catenin signalling pathway, making it a potential therapeutic target for GC.

RNA sequencing reveals widespread transcriptome changes in a renal carcinoma cell line

We used RNA sequencing (RNA-Seq) technology to investigate changes in the transcriptome profile in the Caki-1 clear cell renal cell carcinoma (ccRCC) cells, which overexpress monocyte chemoattractant protein-induced protein 1 (MCPIP1). RNA-Seq data showed changes in 11.6% and 41.8% of the global transcriptome of Caki-1 cells overexpressing wild-type MCPIP1 or its D141N mutant, respectively. Gene ontology and KEGG pathway functional analyses showed that these transcripts encoded proteins involved in cell cycle progression, protein folding in the endoplasmic reticulum, hypoxia response and cell signalling. We identified 219 downregulated transcripts in MCPIP1-expressing cells that were either unchanged or upregulated in D141N-expressing cells. We validated downregulation of 15 transcripts belonging to different functional pathways by qRT-PCR. The growth and viability of MCPIP1-expressing cells was reduced because of elevated p21Cip1 levels. MCPIP1-expressing cells also showed reduced levels of DDB1 transcript that encodes component of the E3 ubiquitin ligase that degrades p21Cip1. These results demonstrate that MCPIP1 influences the growth and viability of ccRCC cells by increasing or decreasing the transcript levels for proteins involved in cell cycle progression, protein folding, hypoxia response, and cell signaling.

MiR-34a-3p alters proliferation and apoptosis of meningioma cells in vitro and is directly targeting SMAD4, FRAT1 and BCL2

Micro (mi)RNAs are short, noncoding RNAs and deregulation of miRNAs and their targets are implicated in tumor generation and progression in many cancers. Meningiomas are mostly benign, slow growing tumors of the central nervous system with a small percentage showing a malignant phenotype.

Following in silico prediction of potential targets of miR-34a-3p, SMAD4, FRAT1, and BCL2 have been confirmed as targets by dual luciferase assays with co-expression of miR-34a-3p and reporter gene constructs containing the respective 3'UTRs. Disruption of the miR-34a-3p binding sites in the 3'UTRs resulted in loss of responsiveness to miR-34a-3p overexpression. In meningioma cells, overexpression of miR-34a-3p resulted in decreased protein levels of SMAD4, FRAT1 and BCL2, while inhibition of miR-34a-3p led to increased levels of these proteins as confirmed by Western blotting. Furthermore, deregulation of miR-34a-3p altered cell proliferation and apoptosis of meningioma cells in vitro.

We show that SMAD4, FRAT1 and BCL2 are direct targets of miR-34a-3p and that deregulation of miR-34a-3p alters proliferation and apoptosis of meningioma cells in vitro. As part of their respective signaling pathways, which are known to play a role in meningioma genesis and progression, deregulation of SMAD4, FRAT1 and BCL2 might contribute to the aberrant activation of these signaling pathways leading to increased proliferation and inhibition of apoptosis in meningiomas.

Knockdown of FRAT1 inhibits hypoxia-induced epithelial-to-mesenchymal transition via suppression of the Wnt/β-catenin pathway in hepatocellular carcinoma cells

Hypoxia-induced epithelial-to-mesenchymal transition (EMT) in hepatocellular carcinoma (HCC) was investigated. Frequently rearranged in advanced T-cell lymphomas-1 (FRAT1) is a positive regulator of the Wnt/β-catenin signaling pathway and is overexpressed in many human tumors. However, the expression and role of FRAT1 in HCC has not been elucidated. In this study, we investigated the effect of FRAT1 on EMT process in HCC cells induced by hypoxia. Our results showed that FRAT1 is highly expressed in HCC tissues and cell lines. Hypoxia significantly induced FRAT1 expression in HCC cells. FRAT1 knockdown inhibited hypoxia-induced cell migration/invasion, downregulation of epithelial markers and upregulation of mesenchymal markers. Moreover, FRAT1 knockdown suppressed the expression levels of β-catenin, cyclin D1 and c-myc in HCC cells under the same hypoxic condition. Our results revealed that FRAT1 is a hypoxia factor that is critical for the induction of EMT in HCC cells. These data suggest a potential role for targeting FRAT1 in the prevention of hypoxia-induced HCC cancer progression and metastasis mediated by EMT.

Frequently rearranged in advanced T‑cell lymphomas‑1 demonstrates oncogenic properties in prostate cancer

Prostate cancer is the fifth most common cause of cancer-associated mortality for males worldwide. Although dysregulation of the β-catenin/T-cell factor (TCF) pathway has been previously reported in prostate cancer, the mechanisms underlying this process remain unknown. Frequently rearranged in advanced T-cell lymphomas-1 (FRAT1) functions as a positive regulator of the β-catenin/TCF signaling pathway. However, to the best of our knowledge, the molecular association between FRAT1 and the β-catenin/TCF pathway in prostate cancer has not been investigated. In the present study, FRAT1 expression was analyzed in normal prostate tissues and prostate adenocarcinoma samples using publicly available databases, a commercial tissue microarray and immunohistochemistry techniques. In addition, FRAT1 expression levels were altered by overexpression or RNA interference-mediated depletion in prostate cancer cells. The effects of FRAT1 expression on tumor growth were determined using cell growth curves in vitro and xenografts in nude mice in vivo. The effects of FRAT1 on β-catenin/TCF activity were measured using the TOPFLASH reporter assay. FRAT1 was expressed exclusively in the nuclei of normal prostate basal cells, and nuclear FRAT1 was detected in 68% (40/59) of prostate adenocarcinoma samples. In addition, FRAT1 activated the TCF luciferase reporter gene promoter in prostate cancer cells, and was observed to promote the growth of prostate cancer cells in vitro. Furthermore, FRAT1 expression was sufficient to transform NIH3T3 mouse embryonic fibroblast cells and lead to tumor formation in vivo. These results suggest that FRAT1 demonstrates oncogenic properties in prostate cancer, potentially by suppressing the inhibitory effect of nuclear glycogen synthase 3β against β-catenin/TCF activity, thus activating the Wnt/β-catenin signaling pathway and promoting cell growth.

Epigenetic silencing of miR-490-3p promotes development of an aggressive colorectal cancer phenotype through activation of the Wnt/β-catenin signaling pathway

The Wnt/β-catenin pathway is known to contribute to colorectal cancer (CRC) progression, although little is known about the contribution of β-catenin on this process. We investigated the role of miR-490-3p, which was recently reported to suppress tumorigenesis through its effect on Wnt/β-catenin signaling. We found that hypermethylation of the miR-490-3p promoter down-regulates miR-490-3p expression in CRC tissue. Gain- and loss-of-function assays in vitro and in vivo reveal that miR-490-3p suppresses cancer cell proliferation by inducing apoptosis and inhibits cell invasiveness by repressing the initiation of epithelial-to-mesenchymal transition (EMT), a key mechanism in cancer cell invasiveness and metastasis. The frequently rearranged in advanced T-cell lymphomas (FRAT1) protein was identified as a direct target of miR-490-3p and contributes to its tumor-suppressing effects. miR-490-3p appears to have an inhibitory effect on β-catenin expression in nuclear fractions of CRC cells, whereas FRAT1 expression is associated with the accumulation of β-catenin in the nucleus of cells, which could be weakened by transfection with miR-490-3p. Our findings suggest that the miR-490-3p/FRAT1/β-catenin axis is important in CRC progression and provides new insight into the molecular mechanisms underlying CRC. They may help to confirm the pathway driving CRC aggressiveness and serve for the development of a novel miRNA-targeting anticancer therapy.

Silencing of FRAT1 by siRNA inhibits the proliferation of SGC7901 human gastric adenocarcinoma cells

Frequently rearranged in advanced T cell lymphomas-1 (FRAT1) positively regulates the Wnt/β-catenin signaling pathway by inhibiting glycogen synthase kinase-3 mediated phosphorylation of β-catenin. FRAT1 is a proto-oncogene, implicated in tumorigenesis. The present study aimed to investigate the effects of FRAT1 silencing on the proliferation and apoptosis of SGC7901 cells. FRAT1 in SGC7901 cells was silenced by RNA interference. Reverse transcription-quantitative polymerase chain reaction was used for the analysis of FRAT1 mRNA and western blotting was used to evaluate FRAT1 and β-catenin protein levels. Cell proliferation was analyzed by the MTT assay. Cell cycle distribution and apoptosis were analyzed by flow cytometry. The expression of FRAT1 mRNA, FRAT1 and β-catenin protein in FRAT1-silenced SGC7901 cells were reduced significantly compared to untreated cells. The proliferation of FRAT1 silenced SGC7901 cells decreased significantly The FRAT1 silenced SGC7901 cells were arrested at G0/G1 stage to a greater degree, and apoptosis was increased. In summary, silencing of FRAT1 inhibits SGC7901 cell proliferation and induces apoptosis, possible through a reduction in β-catenin expression. FRAT1 may serve as a prognostic biomarker and therapeutic target for gastric cancer.

The clinical significance of FRAT1 and ABCG2 expression in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant tumor with intrinsic resistance to cytotoxic agents. The molecular mechanisms associated with high malignancy and resistance to chemotherapy and radiotherapy have not been fully elucidated. This study investigated the clinicopathological significances of frequently rearranged in advanced T-cell lymphomas-1 (FRAT1) and ATP-binding cassette subfamily G member 2 (ABCG2) expression in PDAC. FRAT1 and ABCG2 protein expression in 106 PDAC, 35 peritumoral tissues, 55 benign pancreatic tissues, and 13 normal pancreatic tissues was measured by immunohistochemistry. FRAT1 and ABCG2 protein was overexpressed in PDAC tumors compared to peritumoral tissues, benign pancreatic tissues, and normal pancreatic tissues (P < 0.01). The percentage of cases with positive FRAT1 and ABCG2 overexpression was significantly higher in PDAC patients with poor differentiation, lymph node metastasis, invasion, and TNM stage III/IV disease than in patients with well-differentiated tumor, no lymph node metastasis and invasion, and TNM stage I/II disease (P < 0.05 or P < 0.01). In pancreatic tissues with benign lesions, tissues with positive FRAT1 and ABCG2 protein expression exhibited dysplasia or intraepithelial neoplasia. Kaplan-Meier survival analysis showed that PDAC patients with positive FRAT1 and ABCG2 expression survived significantly shorter than patients with negative FRAT1 and ABCG2 expression (P < 0.05 or P < 0.001). Cox multivariate analysis revealed that positive FRAT1 and ABCG2 expression was an independent poor prognosis factor in PDAC patients. FRAT1 and ABCG2 overexpression is associated with carcinogenesis, progression, and poor prognosis in patients with PDAC.

Overexpression of FRAT1 is associated with malignant phenotype and poor prognosis in human gliomas

Glioma is the most common malignancy of the central nervous system. Approximately 40 percent of intracranial tumors are diagnosed as gliomas. Difficulties in treatment are associated closely with the malignant phenotype, which is characterized by excessive proliferation, relentless invasion, and angiogenesis. Although the comprehensive treatment level of brain glioma is continuously progressing, the outcome of this malignancy has not been improved drastically. Therefore, the identification of new biomarkers for diagnosis and therapy of this malignancy is of significant scientific and clinical value. FRAT1 is a positive regulator of the Wnt/β-catenin signaling pathway and is overexpressed in many human tumors. In the present study, we investigated the expression status of FRAT1 in 68 patients with human gliomas and its correlation with the pathologic grade, proliferation, invasion, angiogenesis, and prognostic significance. These findings suggest that FRAT1 may be an important factor in the tumorigenesis and progression of glioma and could be explored as a potential biomarker for pathological diagnosis, an indicator for prognosis, and a target for biological therapy of malignancy.

Expression and Splice Variant Analysis of Human TCF4 Transcription Factor in Esophageal Cancer

Objective: The human T cell transcription factor-4 (TCF4) interacts functionally with β-catenin in the Wnt signaling pathway, whose deregulation is involved in the tumorigenesis of various types of cancers. Recent studies showed that TCF4 mRNAs were subject to alternative splicing, which was proposed to be important in regulating transactivational properties of the corresponding protein isoforms. Here we investigated the splicing isoforms and the roles of TCF4 in human esophageal squamous cell carcinoma.

Methods: RT-PCR and subsequent cloning and sequencing were applied to identify the splicing isoforms. Western blotting and realtime PCR were used to analyze the expression of TCF4. Knockdown of TCF4 was achieved with siRNA and stable transfection of expression vectors was performed.

Results: Our results showed there were a lot of different isoforms of TCF4 mRNA both in human esophageal cancers and cell line. Further, knockdown of TCF4E isoform expression in EC109 cells inhibited the cell growth, while overexpression of TCF4M isoform did not alter its transcription activity. Moreover, sixteen potential binding proteins of TCF4 were preliminarily identified by mass spectrometry.

Conclusions: Our data suggested that deregulation of TCF4 isoforms may contribute to the tumorigenesis of ESCC.

The clinical pathological significance of FRAT1 and ROR2 expression in cartilage tumors

PURPOSE

Chondrosarcoma is a malignant bone tumor with poor prognosis. Surgical treatment is the first choice for chondrosarcomas. Chondrosarcoma is not sensitive to chemotherapy and radiotherapy. Identification of biological markers is important for the early diagnosis and targeted treatment of chondrosarcoma. This study investigated the protein expression and clinicopathological significance of ROR2 and FRAT1 in 59 chondrosarcomas and 33 osteochondromas.

METHODS

ROR2 and FRAT1 protein expression in tissues was measured by immunohistochemistry.

RESULTS

The percentage of positive ROR2 and FRAT1 expression was significantly higher in patients with chondrosarcoma than in patients with osteochondroma (P < 0.01). The percentage of positive ROR2 and FRAT1 expression was significantly lower in patients with histological grade I, AJCC stage I/II stage, Enneking stage I, non-metastatic and invasive chondrosarcoma than patients with histological grade III, AJCC stage III/IV, Enneking stage II + III, metastatic and invasive chondrosarcoma (P < 0.05 or P < 0.01). ROR2 expression was positively correlated with FRAT1 expression in chondrosarcoma. Kaplan-Meier survival analysis demonstrated that histological grade, AJCC stage, Enneking stage, metastasis, invasion, and ROR2 and FRAT1 expression significantly correlated with a short mean survival time of patients with chondrosarcoma (P < 0.05 or P < 0.01). Cox multivariate analysis showed that positive ROR2 and FRAT1 expression was an independent prognostic factor that negatively correlated with postoperative survival and positively correlated with mortality.

CONCLUSION

Positive ROR2 and FRAT1 expression is associated with the progression and poor prognosis of chondrosarcoma.

PITX2: a promising predictive biomarker of patients' prognosis and chemoradioresistance in esophageal squamous cell carcinoma

The paired-like homeodomain transcription factor 2 (PITX2), a downstream effector of wnt/β-catenin signaling, is well known to play critical role during normal embryonic development. However, the possible involvement of PITX2 in human tumorigenesis remains unclear. In this study, we extend its function in human esophageal squamous cell carcinoma (ESCC). The real-time PCR, Western blotting and immunohistochemistry (IHC) methods were applied to examine expression pattern of PITX2 in two different cohorts of ESCC cases treated with definitive chemoradiotherapy (CRT). Receiver operating characteristic (ROC) curve analysis was used to determine the cutoff point for PITX2 high expression in the training cohort. The ROC-derived cutoff point was then subjected to analyze the association of PITX2 expression with patients' survival and clinical characteristics in training and validation cohort, respectively. The expression level of PITX2 was significantly higher in ESCCs than that in normal esophageal mucosa. There was a positive correlation between PITX2 expression and clinical aggressiveness of ESCC. Importantly, high expression of PITX2 was observed more frequently in CRT resistant group than that in CRT effective group (p < 0.05). Furthermore, high expression of PITX2 was associated with poor disease-specific survival (p < 0.05) in ESCC. Then, the MTS, clonogenic survival fraction and cell apoptosis experiments showed that knockdown of PITX2 substantially increased ESCC cells sensitivity to ionizing radiation (IR) or cisplatin in vitro. Thus, the expression of PITX2, as detected by IHC, may be a useful tool for predicting CRT resistance and serves as an independent molecular marker for poor prognosis of ESCC patients treated with definite CRT.

Knockdown of FRAT1 expression by RNA interference inhibits human glioblastoma cell growth, migration and invasion

BACKGROUND

FRAT1 positively regulates the Wnt/β-catenin signaling pathway by inhibiting GSK-3-mediated phosphorylation of β-catenin. It was originally characterized as a protein frequently rearranged in advanced T cell lymphoma, but has recently also been identified as a proto-oncogene involved in tumorigenesis. Our previous studies showed that FRAT1 was dramatically overexpressed in gliomas and its expression level was significantly increased along with clinicopathological grades.

METHODS

In the current study, we used RT-PCR and Western blotting to assess the mRNA and protein levels of FRAT1 in three glioma cell lines. In addition, to evaluate its functional role in gliomas, we examined the effects of FRAT1 knockdown on proliferation, migration and invasion in vitro and tumor growth in vivo using glioblastoma U251 cells and RNAi.

RESULTS

FRAT1 was highly expressed in all three glioma cell lines. RNAi-mediated down-regulation of endogenous FRAT1 in human glioblastoma U251 cells resulted in suppression of cell proliferation, arrest of cell cycle, inhibition of cell migration and invasion in vitro. Moreover, FRAT1 depletion significantly impaired tumor xenograft growth in nude mice.

CONCLUSIONS

Our results highlight the potential role of FRAT1 in tumorigenesis and progression of glioblastoma. These findings provide a biological basis for FRAT1 as a potential molecular marker for improved pathological grading and as a novel candidate therapeutic target for glioblastoma management.

Inhibition of atypical protein kinase Cι induces apoptosis through autophagic degradation of β-catenin in esophageal cancer cells

Atypical protein kinase Cι (PKCι) has been identified as an oncoprotein in esophageal squamous cell carcinomas. However, the mechanisms underlying the role of PKCι in this disease remain unclear. In the present work, we found that inhibition of PKCι expression by RNAi induced apoptosis via the down-regulation of β-catenin in esophageal cancer cells. Furthermore, we found that PKCι regulated β-catenin in an autophagy dependent way. Since down-regulation of β-catenin induced by knockdown of PKCι could be rescued by autophagy inhibition; knockdown of PKCι activated autophagy and promoted the recruitment of β-catenin into autophagosome. These results suggested that PKCι positively regulated β-catenin through negatively regulated autophagy and depletion of PKCι promoted apoptosis via autophagic degradation of β-catenin in esophageal cancer cells. These data provide new insights into PKCι signaling in human cancer.

PLK1 Is transcriptionally activated by NF-κB during cell detachment and enhances anoikis resistance through inhibiting β-catenin degradation in esophageal squamous cell carcinoma

PURPOSE

To investigate the molecular mechanisms through which polo-like kinase-1 (PLK1) takes part in anoikis resistance of esophageal squamous cell carcinoma (ESCC) cells.

EXPERIMENTAL DESIGN

The role of PLK1 in cell anoikis resistance was examined by ectopic gene expression and siRNA-mediated knockdown. Glutathione S-transferase pull-down and co-immunoprecipitation assays were utilized to investigate PLK1-interacting proteins. Electrophoretic mobility shift assay, chromatin immunoprecipitation, and reporter gene assays were carried out to identify the transcription factors responsible for PLK1 expression during anoikis resistance.

RESULTS

We found that detachment of ESCC cells triggers the upregulation of PLK1. Elevated PLK1 expression contributes to protection against anoikis in cancer cells through the regulation of β-catenin expression. Moreover, we showed that, through direct binding to the PLK1 promoter, the NF-κB subunit RelA transcriptionally activates PLK1, which inhibits the ubiquitination and degradation of β-catenin. Inhibition of the NF-κB pathway restores the sensitivity of cancer cells to anoikis by downregulating PLK1/β-catenin expression. In addition, RelA gene amplification and protein overexpression was significantly correlated with PLK1 expression in ESCC tissues.

CONCLUSIONS

Our findings suggest that upregulation of PLK1 triggered by cell detachment is regulated by RelA at the transcriptional level. PLK1 protects esophageal carcinoma cells from anoikis through modulation of β-catenin protein levels by inhibiting their degradation. Taken together, this study reveals critical mechanisms involved in the role of RelA/PLK1/β-catenin in anoikis resistance of ESCC cells.

WNT/β-catenin pathway is modulated in asthma patients and LPS-stimulated RAW264.7 macrophage cell line

In the present study, we investigated the possibility that the WNT/β-catenin pathway plays a role in inflammatory responses both in an human inflammatory condition and in an in vitro inflammation model. First, we analyzed gene expression patterns of the peripheral blood cells from asthma patients compared with those from normal subjects using microarray analyses. We found that intracellular signaling molecules of the WNT/β-catenin pathway were significantly changed in asthma patients compared with the levels in the controls. Next, we determined whether major components of the WNT/β-catenin pathway were involved in the lipopolysaccharide (LPS)-induced inflammatory response of the RAW264.7 macrophage cell line. Among the members of WNT/β-catenin pathway, the protein levels of low-density lipoprotein receptor-related protein (LRP) 6, dishevelled (DVL) 2, and AXIN1, which were measured using western blotting, did not significantly change in the presence of LPS. In contrast, the LPS induced a rapid phosphorylation of glycogen synthase kinase (GSK) 3β and accumulation of β-catenin protein. It was found that β-catenin plays a significant role in the LPS-induced inflammatory response through the performance of small interfering RNA (siRNA) transfection experiments. The mRNA level of IL-6 was significantly elevated in β-catenin siRNA-transfected cells compared with that in control siRNA-transfected cells after LPS treatment. Furthermore, nuclear factor-κB (NF-κB) activity was also significantly increased in β-catenin siRNA-transfected cells compared with the level seen in control siRNA-transfected cells. Taken together, these results suggest that β-catenin plays a role as a negative regulator, preventing the overproduction of inflammatory cytokines such as IL-6 in LPS-induced inflammatory responses.

The expression profile of FRAT1 in human gliomas

FRAT1 was originally characterized as a protein frequently rearranged in advanced T cell lymphoma, which inhibits GSK-3-mediated phosphorylation of beta-catenin and positively regulates the Wnt signaling pathway. FRAT1 has been identified as a proto-oncogene involved in tumorigenesis. Previous studies have shown that FRAT1 is strikingly overexpressed in some human cancers. However, the relationship between FRAT1 and human gliomas is unclear. In this study, we detected the expression of FRAT1 in human gliomas by immunohistochemistry, Western blot and RT-PCR. FRAT1 was found to be specifically expressed in the majority of glioma samples, and their expression levels increased markedly with the increase of WHO grades. In addition, there was a positive correlation between FRAT1 immunoreactivity score (IRS) and beta-catenin IRS. Our results suggest that FRAT1 may be an important factor in the tumorigenesis and progression of gliomas, and could be used as a potential molecular marker for pathological diagnosis and a target for biological therapy.

Frat oncoproteins act at the crossroad of canonical and noncanonical Wnt-signaling pathways

Wnt-signal transduction is critical for development and tissue homeostasis in a wide range of animal species and is frequently deregulated in human cancers. Members of the Frat/GBP family of glycogen synthase kinase 3beta (Gsk3b)-binding oncoproteins are recognized as potent activators of the Wnt/beta-catenin pathway in vertebrates. Here, we reveal a novel, Gsk3b-independent function of Frat converging on the activation of JNK and AP-1. Both these have been used as readouts for the noncanonical Frizzled/PCP pathway, which controls polarized cell movements and the establishment of tissue polarity. We find that Frat synergizes with Diversin, the mammalian homolog of the Drosophila PCP protein diego, in the activation of JNK/AP-1 signaling. Importantly, Frat mutants deficient for binding to Gsk3b retain oncogenic activity in vivo, suggesting that Wnt/beta-catenin-independent events contribute to Frat-induced malignant transformation. The observed activities of Frat are reminiscent of the dual function of Dishevelled in the Wnt/beta-catenin and Frizzled/PCP pathways and suggest that Frat may also function to bridge canonical and noncanonical Wnt pathways.

Gene and microRNA analysis of neutrophils from patients with polycythemia vera and essential thrombocytosis: down-regulation of micro RNA-1 and -133a

Background

Since the V617F mutation in JAK2 may not be the initiating event in myeloprofilerative disorders (MPDs) we compared molecular changes in neutrophils from patients with polycythemia vera (PV) and essential thrombocythosis (ET), to neutrophils stimulated by G-CSF administration and to normal unstimulated neutrophils

Methods

A gene expression oligonucleotide microarray with more than 35,000 probes and a microRNA (miR) expression array with 827 probes were used to assess neutrophils from 6 MPD patients; 4 with PV and 2 with ET, 5 healthy subjects and 6 healthy subjects given G-CSF. In addition, neutrophil antigen expression was analyzed by flow cytometry and 64 serum protein levels were analyzed by ELISA.

Results

Gene expression profiles of neutrophils from the MPD patients were similar but distinct from those of healthy subjects, either unstimulated or G-CSF-mobilized. The differentially expressed genes in MPD neutrophils were more likely to be in pathways involved with inflammation while those of G-CSF-mobilized neutrophils were more likely to belong to metabolic pathways. In MPD neutrophils the expression of CCR1 was increased and that of several NF-κB pathway genes were decreased. MicroRNA miR-133a and miR-1 in MPD neutrophils were down-regulated the most. Levels of 11 serum proteins were increased in MPD patients including MMP-10, MMP-13, VCAM, P-selectin, PDGF-BB and a CCR1 ligand, MIP-1α.

Conclusion

These studies showed differential expression of genes particularly involved in inflammatory pathways including the NF-κB pathway and down-regulation of miR-133a and miR-1. These two microRNAs have been previous associated with certain cancers as well as the regulation of hyperthrophy of cardiac and skeletal muscle cells. These changes may contribute to the clinical manifestations of the MPDs.