Short hairpin RNA targeting beta-catenin suppresses cell proliferation and induces apoptosis in human gastric carcinoma cells

MiRNA-1225 Inhibits Osteosarcoma Tumor Growth and Progression by Targeting YWHAZ

Introduction

Osteosarcoma is the most common bone tumor and is characterized by the presence of malignant mesenchymal cells produced in the bone stroma. MiRNAs are known to function as post-transcriptional negative regulators of gene expression. Emerging evidence showed that miR-1225-5P functions as a tumor suppressor in several types of cancers. The detailed mechanisms of which miR-1225-5P suppresses tumor growth are not fully understood. The objective of the present study was to test the hypothesis that miR-1225-5P inhibits osteosarcoma cell growth in vitro and tumor growth in vivo by targeting YWHAZ expression.

Methods

Real-time PCR and Western blot were carried out to test the expression of miR-1225-5P and YWHAZ in osteosarcoma cell lines. Luciferase assay was used to demonstrate whether miR-1225-5P targets YWHAZ 3ʹ UTR. To assess the function of miR-1225-5P in human osteosarcoma cell lines, gain-of-function and loss-of-function of miR-1225-5P were performed by transfecting miR-1225-5P mimic or miR-1225-5P inhibitor into osteosarcoma cell lines. Furthermore, cell cycle analysis was performed to elucidate the possible mechanisms of the action of miR-1225-5P and YWHAZ in human osteosarcoma cells. The potential therapeutic effect of miR-1225-5p was tested in human osteosarcoma xenograft mouse model, by intravenous injection of miR-1225-5P into nude mice. Tumor sizes were measured and lung metastasis was counted after the mice were sacrificed.

Results

The expression of miR-1225-5P was inversely correlated with the expression of YWHAZ in human osteosarcoma cell lines. Database search revealed that miR-1225-5P targeted YWHAZ 3ʹ UTR. Transfection of miR-1225-5P mimic downregulated YWHAZ expression, which was demonstrated by real-time PCR, Western blot and luciferase assay. Over-expression of miR-1225-5P reduced human osteosarcoma cell growth, migration and invasion by downregulating YWHAZ expression. Cell growth, migration and invasion were increased by inhibiting miR-1225-5P in human osteosarcoma cells. The inhibition of cell growth, migration and invasion was rescued by over-expression of YWHAZ in osteosarcoma cells. Cell cycle analysis revealed that miR-1225-5P inhibited G1/G0 phase exit. In vivo xenograft model demonstrated that miR-1225-5P inhibited in vivo osteosarcoma tumor growth and lung metastasis.

Conclusion

Our findings suggested that miR-1225-5P inhibits osteosarcoma cell growth in vitro and tumor growth in vivo by targeting YWHAZ. This study suggested that miR-1225-5P can serve as a potential therapeutic method for treating osteosarcoma.

Chlorogenic acid-enriched extract of Ilex kudingcha C.J. Tseng tea inhibits neutrophil recruitment in injured zebrafish by promoting reverse migration via the focal adhesion pathway

Neutrophil-regulated inflammation plays crucial roles in tissue damage and repair. Dysregulation of the neutrophil response system can contribute to diseases such as cancer. Clearance of excessive neutrophils at the site of inflammation by reverse migration provides a promising strategy to mitigate the negative effects. Chlorogenic acid treatment of injured zebrafish embryos showed low-developmental toxicity. Using a transgenic zebrafish Tg (mpx: egfp) model, chlorogenic acid-enriched kudingcha extract promoted neutrophil reverse migration via phosphorylation of ERK and AKT. Using i-TRAQ analysis, differentially expressed proteins involved in focal adhesion were identified, such as: Cdc42, SRC, MLC, ITGA, and Calpain. In support of this, ERK and AKT proteins are involved in the focal adhesion pathway. Real time qPCR determined that CGA downregulates genes associated with cancer metastasis, such as: HSPA5, YWHAZ, RP17, and ITGAV. Together, these results suggest that CGA-enriched Kudingcha extract may have potential as an anticancer or anti-inflammatory therapeutic agent. PRACTICAL APPLICATIONS: Ilex kudingcha C.J Tseng, commonly referred to as the large-leaved kudingcha, is a tea variety naturally rich in chlorogenic acid. Chlorogenic acid, the ester of caffeic and quinic acids, has antioxidant, antibacterial, anticancer, and anti-inflammatory, activities. Kudingcha has several known biological functions, including: anticancer, anti-inflammatory, antidiabetic, and hypolipidemic effects. Treatment with kudingcha extract reduces the recruitment of neutrophils, potentially by inhibiting focal adhesion, and activation of cancer metastasis-related genes. Importantly, kudingcha extract could be used as an alternative nutritional supplement for anticancer or anti-inflammation via its ability to suppress neutrophil recruitment.

PERP-ing into diverse mechanisms of cancer pathogenesis: Regulation and role of the p53/p63 effector PERP

The tetraspan plasma membrane protein PERP (p53 apoptosis effector related to PMP22) is a lesser-known transcriptional target of p53 and p63. A member of the PMP22/GAS3/EMP membrane protein family, PERP was originally identified as a p53 target specifically trans-activated during apoptosis, but not during cell-cycle arrest. Several studies have since shown downregulation of PERP expression in numerous cancers, suggesting that PERP is a tumour suppressor protein. This review focusses on the important advances made in elucidating the mechanisms regulating PERP expression and its function as a tumour suppressor in diverse human cancers, including breast cancer and squamous cell carcinoma. Investigating PERP's role in clinically-aggressive uveal melanoma has revealed that PERP engages a positive-feedback loop with p53 to regulate its own expression, and that p63 is required beside p53 to achieve pro-apoptotic levels of PERP in this cancer. Furthermore, the recent discovery of the apoptosis-mediating interaction of PERP with SERCA2b at the plasma membrane-endoplasmic reticulum interface demonstrates a novel mechanism of PERP stabilisation, and how PERP can mediate Ca²⁺ signalling to facilitate apoptosis. The multi-faceted role of PERP in cancer, involving well-documented functions in mediating apoptosis and cell-cell adhesion is discussed, alongside PERP's emerging roles in epithelial-mesenchymal transition, and PERP crosstalk with inflammation signalling pathways, and other signalling pathways. The potential for restoring PERP expression as a means of cancer therapy is also considered.

Wnt Signalling in Gastrointestinal Epithelial Stem Cells

Wnt signalling regulates several cellular functions including proliferation, differentiation, apoptosis and migration, and is critical for embryonic development. Stem cells are defined by their ability for self-renewal and the ability to be able to give rise to differentiated progeny. Consequently, they are essential for the homeostasis of many organs including the gastrointestinal tract. This review will describe the huge advances in our understanding of how stem cell functions in the gastrointestinal tract are regulated by Wnt signalling, including how deregulated Wnt signalling can hijack these functions to transform cells and lead to cancer.

CDK5RAP3 acts as a tumor suppressor in gastric cancer through inhibition of β-catenin signaling

CDK5RAP3 was isolated as a binding protein of the Cdk5 activator p35. Although CDK5RAP3 has been implicated in cancer progression, its expression and function have not been investigated in gastric cancer. Our study demonstrated that the mRNA and protein levels of CDK5RAP3 were markedly decreased in gastric tumor tissues when compared with respective adjacent non-tumor tissues. CDK5RAP3 in gastric cancer cells significantly reduced cell proliferation, migration, invasion and tumor xenograft growth through inhibition of β-catenin. Secondly, CDK5RAP3 was found to suppress the phosphorylation of GSK-3β (Ser9), leading to the phosphorylation (Ser37/Thr41) and subsequent degradation of β-catenin. Lastly, the prognostic value of CDK5RAP3 for overall survival was found to be dependent on β-catenin cytoplasm/nucleus localization in human gastric cancer samples. Collectively, our results demonstrated that CDK5RAP3 negatively regulates the β-catenin signaling pathway by repressing GSK-3β phosphorylation and could be a potential therapeutic target for gastric cancer.

Characterization of bovine A20 gene: Expression mediated by NF-κB pathway in MDBK cells infected with bovine viral diarrhea virus-1

Cytokine production for immunological process is tightly regulated at the transcriptional and posttranscriptional levels. The NF-κB signaling pathway maintains immune homeostasis in the cell through the participation of molecules such as A20 (TNFAIP3), which is a key regulatory factor in the immune response, hematopoietic differentiation, and immunomodulation. Although A20 has been identified in mammals, and despite recent efforts to identify A20 members in other higher vertebrates, relatively little is known about the composition of this regulator in other classes of vertebrates, particularly for bovines. In this study, the genetic context of bovine A20 was explored and compared against homologous genes in the human, mouse, chicken, dog, and zebrafish chromosomes. Through in silico analysis, several regions of interest were found conserved between even phylogenetically distant species. Additionally, a protein-deduced sequence of bovine A20 evidenced many conserved domains in humans and mice. Furthermore, all potential amino acid residues implicated in the active site of A20 were conserved. Finally, bovine A20 mRNA expression as mediated by the bovine viral diarrhea virus and poly (I:C) was evaluated. These analyses evidenced a strong fold increase in A20 expression following virus exposure, a phenomenon blocked by a pharmacological NF-κB inhibitor (BAY 117085). Interestingly, A20 mRNA had a half-life of only 32min, likely due to adenylate- and uridylate-rich elements in the 3'-untranslated region. Collectively, these data identify bovine A20 as a regulator of immune marker expression. Finally, this is the first report to find the bovine viral diarrhea virus modulating bovine A20 activation through the NF-κB pathway.

Reactivating p53 functions by suppressing its novel inhibitor iASPP: a potential therapeutic opportunity in p53 wild-type tumors

Although mutational inactivation of p53 is found in 50% of all human tumors, a subset of tumors display defective p53 function, but retain wild-type (WT) p53. Here, direct and indirect mechanisms leading to the loss of WT p53 activities are discussed. We summarize the oncogenic roles of iASPP, an inhibitor of WT p53, in promoting proliferation, invasion, drug or radiation-resistance and metastasis. From the therapeutic view, we highlight promising perspectives of microRNA-124, peptide and small molecules that reduce or block iASPP for the treatment of cancer. High iASPP expression enhances proliferation, aggressive behavior, the resistance to radiation/chemotherapy and correlates with poor prognosis in a range of human tumors. Overexpression of iASPP accelerates tumorigenesis and invasion through p53-dependent and p53-independent mechanisms. MicroRNA-124 directly targets iASPP and represses the growth and invasiveness of cancer cells. The disruption of iASPP-p53 interaction by a p53-derived peptide A34 restores p53 function in cancer cells. The inhibition of iASPP phosphorylation with small molecules induces p53-dependent apoptosis and growth suppression. The mechanisms underlying aberrant expression of iASPP in human tumors should be further investigated. Reactivating WT p53 functions by targeting its novel inhibitor iASPP holds promise for potential therapeutic interventions in the treatment of WT p53-containing tumors.

miR-129-1-3p promote BGC-823 cell proliferation by targeting PDCD2

MicroRNAs (miRNAs) are the class of small noncoding RNAs, and play an important role in the regulation of gene expression at the posttranscriptional level. In this study, we explored the effect of miR-129-1-3p on the growth and cell cycle of human gastric cancer cell line BGC-823. The miR-129-1-3p mimics or inhibitors were transfected into the BGC-823 cell line, and the cell cycle and cell growth was measured by flow cytometry and real-time cell analyzer, respectively. The possible targets of miR-129-1-3p were analyzed by quantitative real time-PCR (QRT-PCR), Western blotting and Luciferase reporter assay. The results showed that miR-129-1-3p could promote the growth and cell cycle of BGC-823 cells. Although protein expression of programmed cell death 2 (PDCD2) was not changed with miR-129-1-3p, QRT-PCR showed that expression of PDCD2 mRNA was negatively related to the miR-129-1-3p. Luciferase reporter assay revealed that PDCD2 is one of the targets of miR-129-1-3p. Our results indicated that miR-129-1-3p might promote proliferation of BGC-823 cells by targeting PDCD2.

Quantitatively controlling expression of miR-17~92 determines colon tumor progression in a mouse tumor model

The miRNA cluster miR-17~92 targets mRNAs involved in distinct pathways that either promote or inhibit tumor progression. However, the cellular and molecular mechanisms underlying miR-17~92 cluster-mediated protumorigenic or anti-tumorigenic effects have not been studied. Herein, we determined that inhibition of colon cancer progression is dictated by quantitatively controlling expression of the miR-17~92 cluster. miR-19 in the context of the miR-17~92 cluster at medium levels promoted tumor metastasis through induction of Wnt/β-catenin-mediated epithelial-mesenchymal transition by targeting to the tumor-suppressor gene, PTEN. However, higher levels of the miR-17~92 cluster switched from PTEN to oncogenes, including Ctnnb1 (β-catenin) via miR-18a, which resulted in inhibition of tumor growth and metastasis. However, overexpression of Ctnnb1in tumor cells with high-level miR-17~92 did not lead to an increase in the levels of β-catenin protein, suggesting that other factors regulated by higher levels of miR-17~92 might also contribute to inhibition of tumor growth and metastasis. Those unidentified factors may negatively regulate the production of β-catenin protein. Collectively, the data presented in this study revealed that higher levels of miR-17~92 were a critical negative regulator for activation of the Wnt/β-catenin pathway and could have a potential therapeutic application.

Wnt/β-catenin signaling pathway may regulate the expression of angiogenic growth factors in hepatocellular carcinoma

The Wnt/β-catenin signaling pathway plays a key role during hepatocellular carcinoma (HCC) genesis and development. The present study aimed to investigate the effects of the Wnt/β-catenin signaling pathway on the expression of angiogenic growth factors involved in HCC. The HCC HepG2 cell line was transfected with small interfering RNA (siRNA) against β-catenin. After 72 and 96 h, protein was extracted and the expression levels of β-catenin, matrix metalloproteinase (MMP)-2, MMP-9, vascular endothelial growth factor (VEGF)-A, VEGF-C and basic fibroblast growth factor (bFGF) were detected by western blot analysis. β-catenin protein expression was inhibited at both time points. Notably, MMP-2, MMP-9, VEGF-A, VEGF-C and bFGF protein expression levels decreased at 72 h and then increased at 96 h after transfection. Our results demonstrated that in HCC cells, the Wnt/β-catenin signaling pathway may regulate the protein expression of the angiogenic factors, MMP-2, MMP-9, VEGF-A, VEGF-C and bFGF. These proteins were downstream of β-catenin signaling and were also regulated by other factors. In conclusion, the Wnt/β-catenin signaling pathway may contribute to the regulation of HCC angiogenesis, infiltration and metastasis through regulating the expression of these angiogenic factors.

Beta-catenin is vital for the integrity of mouse embryonic stem cells

β-Catenin mediated Wnt-signaling is assumed to play a major function in embryonic stem cells in maintaining their stem cell character and the exit from this unique trait. The complexity of β-catenin action and conflicting results on the role of β-catenin in maintaining the pluripotent state have made it difficult to understand its precise cellular and molecular functions. To attempt this issue we have generated new genetically modified mouse embryonic stem cell lines allowing for the deletion of β-catenin in a controlled manner by taking advantage of the Cre-ER-T2 system and analyzed the effects in a narrow time window shortly after ablation. By using this approach, rather then taking long term cultured β-catenin null cell lines we demonstrate that β-catenin is dispensable for the maintenance of pluripotency associated genes. In addition we observed that the removal of β-catenin leads to a strong increase of cell death, the appearance of multiple clustered functional centrosomes most likely due to a mis-regulation of the polo-like-kinase 2 and furthermore, alterations in chromosome segregation. Our study demonstrates the importance of β-catenin in maintaining correct cellular functions and helps to understand its role in embryonic stem cells.

Chimeric 5/35 adenovirus-mediated Dickkopf-1 overexpression suppressed tumorigenicity of CD44⁺ gastric cancer cells via attenuating Wnt signaling

BACKGROUND

Gastric cancer stem cells (CSCs), which require activation of Wnt signaling to maintain their self-renewal and tumorigenicity, are proposed to be critical targets for effective therapy of gastric carcinomas. Gene therapies that are delivered by adenovirus of serotype 5 (Ad5) or chimeric 5/35(Ad5/35) adenovirus have shown promise for treating various cancers. Here we aimed to develop a gene therapy strategy that targeted gastric CSCs (CD44⁺ cells).

METHODS

CD44⁺ cells were isolated by fluorescence activated cell sorting from both primary gastric cancer cells and cell lines. Expression of adenovirus receptors was examined in CD44⁺ and CD44⁻ cells. A potent Wnt antagonist Dickkopf-1 (DKK1) was delivered into CD44⁺ cells using Ad5/35 (Ad5/35-DKK1). The therapeutic outcomes were evaluated.

RESULTS

Expression of Coxsakievirus adenovirus receptor for Ad5 was significantly reduced, while abundance of CD46, the receptor for Ad5/35, was slightly higher in CD44⁺ cells. Accordingly, CD44⁺ cells were sensitive to Ad5/35 infection, but not to Ad5. Ad5/35-DKK1 introduced DKK1 into CD44⁺ cells and deactivated endogenous Wnt/β-catenin signaling efficiently. Overexpression of DKK1 inhibited survival, anchorage-independent colony formation, and invasion of CD44⁺ cells, which were restored by a GSK-3 specific inhibitor BIO-acetoxime. More importantly, introduction of DKK1 abrogated the tumorigenicity of CD44⁺ cells in vivo. However, Ad5/35-DKK1 only showed minimal cytotoxicity to normal tissue-derived cells, L-02 and GES-1.

CONCLUSIONS

We developed, for the first time, a novel Ad5/35-DKK1-based approach to abrogate Wnt signaling in CSCs and demonstrated that gastric CSC-targeting gene therapy was effective in preclinical experiments.

Serum response factor is overexpressed in esophageal squamous cell carcinoma and promotes Eca-109 cell proliferation and invasion

Recent studies indicate that serum response factor (SRF) is highly expressed in tumors such as hepatocellular, thyroid, esophageal and lung carcinoma. However, the expression and roles of SRF in esophageal squamous cell carcinoma (ESCC) are unclear. In this study, immunohistochemistry was used to compare the expression of SRF in ESCC cases (n=73) and normal controls (n=30). The RNA interference (RNAi) technique was used to knock down the expression of SRF in Eca-109 cells. Cell proliferation, cell cycle stage and invasion were measured with cell counting kit (CCK)-8, flow cytometry and Transwell assays, respectively. Western blotting was used to measure SRF, E-cadherin, β-catenin and cyclin D1 expression in Eca-109 cells treated with siRNA. The study demonstrated that human ESCC has increased expression of SRF. In addition, blocking SRF expression inhibited tumor proliferation and invasion. In conclusion, SRF has the potential to be a new marker for ESCC diagnosis and therapy.

Expression of serum response factor in gastric carcinoma and its molecular mechanisms involved in the regulation of the invasion and migration of SGC-7901 cells

Serum response factor (SRF) is a transcription factor of the MADS box family. To date, DNA binding sites for SRF [serum response elements (SREs)] have been found in the promoters of approximately 50 different genes known to be involved in the regulation cell proliferation, differentiation, and apoptosis. Recent studies have indicated that SRF plays a role in the development of some tumors, including hepatocellular, thyroid, esophageal, and lung carcinomas. However, expression of SRF and its roles in gastric carcinoma are unclear. We found SRF to be highly expressed in human gastric carcinoma as well as ectopic or reduced expression for E-cadherin and β-catenin. Blockage of SRF expression was found to inhibit proliferation, invasion, and migration. We also found that an inhibitor (Y-27632) of Rho-associated coiled kinase (ROCK1), a regulator of actin cytoskeleton that regulates cell adhesion, migration, and motility, suppressed SRF expression as well. These results demonstrate that SRF is involved in the aggressive behavior of gastric carcinoma cells. We also found that the inhibition of ROCK1 by Y-27632 can inhibit the invasion and migration of gastric cells done at least, in part, by attenuating SRF expression.

The role of the TRAF-interacting protein in proliferation and differentiation

Ubiquitination of proteins is a post-translational modification, which decides on the cellular fate of the protein. Addition of ubiquitin moieties to proteins is carried out by the sequential action of three enzymes: E1, ubiquitin-activating enzyme; E2, ubiquitin-conjugating enzyme; and E3, ubiquitin ligase. The TRAF-interacting protein (TRAIP, TRIP, RNF206) functions as Really Interesting New Gene (RING)-type E3 ubiquitin ligase, but its physiological substrates are not yet known. TRAIP was reported to interact with TRAF [tumor necrosis factor (TNF) receptor-associated factors] and the two tumor suppressors CYLD and Syk (spleen tyrosine kinase). Ectopically expressed TRAIP was shown to inhibit nuclear factor-kappa B (NF-κB) signalling. However, recent results suggested a role for TRAIP in biological processes other than NF-κB regulation. Knock-down of TRAIP in human epidermal keratinocytes repressed cellular proliferation and induced a block in the G1/S phase of the cell cycle without affecting NF-κB signalling. TRAIP is necessary for embryonal development as mutations affecting the Drosophila homologue of TRAIP are maternal effect-lethal mutants, and TRAIP knock-out mice die in utero because of aberrant regulation of cell proliferation and apoptosis. These findings underline the tight link between TRAIP and cell proliferation. In this review, we summarize the data on TRAIP and put them into a larger perspective regarding the role of TRAIP in the control of tissue homeostasis.