• Journal of Life Science
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• v.28 no.9
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• pp.1016-1021
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• 2018

Clostridium difficile toxin A causes pseudomembranous colitis. The pathogenesis of toxin A-induced colonic inflammation includes toxin A-dependent epithelial cell apoptosis, resulting in the loss of barrier function provided by epithelial cells against luminal pathogens. Toxin A-dependent epithelial cell apoptosis has been linked to toxin A-induced production of reaction oxygen species and subsequent p38MAPK activation; $p21^{CIP1/WAF1}$ upregulation-dependent cell cycle arrest; cytoskeletal disaggregation; and/or the induction of Fas ligand on epithelial cells. However, the molecular mechanisms underlying toxin A-induced apoptosis remain poorly understood. This study tested whether toxin A could block the Wnt signaling pathway, which is involved in gut epithelial cell proliferation, differentiation and antiapoptotic progression. Toxin A treatment of nontransformed human colonocytes (NCM460) rapidly reduced ${\beta}$-catenin protein, an essential component of the Wnt signaling pathway. Exposure of mouse ileum to toxin A also significantly reduced ${\beta}$-catenin protein levels. MG132 inhibition of proteasome-dependent protein degradation resulted in the recovery of toxin A-mediated reduction of ${\beta}$-catenin, indicating that toxin A may activate intracellular processes, such as $GSK3{\beta}$, to promote degradation of ${\beta}$-catenin. Immunoblot analysis showed that toxin A increased active phosphorylation of $GSK3{\beta}$. Because the Wnt signaling pathway is essential for gut epithelial cell proliferation and anti-apoptotic processes, our results suggest that toxin A-mediated inhibition of the Wnt signaling pathway may be required for maximal toxin A-induced apoptosis of gut epithelial cells.

• Biomolecules & Therapeutics
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• v.26 no.6
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• pp.584-590
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• 2018

Osteoporosis development is closely associated with oxidative stress and reactive oxygen species (ROS). Taurine has potential antioxidant effects, but its role in osteoblasts is not clearly understood. The aim of this study was to determine the protective effects and mechanisms of actions of taurine on hydrogen peroxide ($H_2O_2$)-induced oxidative stress in osteoblast cells. UMR-106 cells were treated with taurine prior to $H_2O_2$ exposure. After treatment, cell viability, apoptosis, intracellular ROS production, malondialdehyde content, and alkaline phosphate (ALP) activity were measured. We also investigated the protein levels of ${\beta}-catenin$, ERK, CHOP and NF-E2-related factor 2 (Nrf2) along with the mRNA levels of Nrf2 downstream antioxidants. The results showed that pretreatment of taurine could reverse the inhibition of cell viability and suppress the induced apoptosis in a dose-dependent manner: taurine significantly reduced $H_2O_2$-induced oxidative damage and expression of CHOP, while it induced protein expression of Nrf2 and ${\beta}-catenin$ and activated ERK phosphorylation. DKK1, a Wnt/${\beta}-catenin$ signaling inhibitor, significantly suppressed the taurine-induced Nrf2 signaling pathway and increased CHOP. Activation of ERK signaling mediated by taurine in the presence of $H_2O_2$ was significantly inhibited by DKK1. These data demonstrated that taurine protects osteoblast cells against oxidative damage via Wnt/${\beta}-catenin$-mediated activation of the ERK signaling pathway.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.3093-3099
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• 2013

Background: Phytic acid (PA) is a polyphosphorylated carbohydrate that can be found in high amounts in most cereals, legumes, nut oil, seeds and soy beans. It has been suggested to play a significant role in inhibition of colorectal cancer. This study was conducted to investigate expression changes of ${\beta}$-catenin and cyclooxygenase-2 (COX-2) and cell proliferation in the adenoma-carcinoma sequence after treatment with rice bran PA by immunocytochemistry. Materials and Methods: Seventy-two male Sprague-Dawley rats were divided into 6 equal groups with 12 rats in each group. For cancer induction two intraperitoneal injections of azoxymethane (AOM) were given at 15 mg/kg bodyweight over a 2-weeks period. During the post initiation phase, two different concentrations of PA, 0.2% (w/v) and 0.5% (w/v) were administered in the diet. Results: Results of ${\beta}$-catenin, COX-2 expressions and cell proliferation of Ki-67 showed a significant contribution in colonic cancer progression. For ${\beta}$-catenin and COX-2 expression, there was a significant difference between groups at p<0.05. With Ki-67, there was a statistically significant lowering the proliferating index as compared to AOM alone (p<0.05). A significant positive correlation (p=0.01) was noted between COX-2 expression and proliferation. Total ${\beta}$-catenin also demonstrated a significant positive linear relationship with total COX-2 (p=0.044). Conclusions: This study indicated potential value of PA extracted from rice bran in reducing colonic cancer risk in rats.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3551-3558
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• 2016

Colorectal cancer (CRC) is a major cause of morbidity and mortality throughout the world, with chronic inflammation and diet as major causes in its development. Chemopreventive effects of natural dietary products have been the focus of studies for prevention over the past decade. This study was conducted to determine the effects of unpolished Thai rice during precancerous stage through the involvement of ${\beta}$-catenin, cyclooxygenase-2 (COX-2) expression and inflammatory cytokines focusing on azoxymethane (AOM)-induced aberrant crypt foci (ACF)-related to CRC. Male Sprague Dawley rats received two injections of AOM (15 mg/kg body weight) at weeks 4 and 5 while rats were treated with 20% or 70% unpolished Thai rice. The rats were sacrificed at week 38 and the colons removed for aberrant crypt foci (ACF) identification. Histopathologic changes, immunohistochemical analysis of ${\beta}$-catenin and COX-2 expression, and cytokine expression of proinflammatory and anti-inflammatory markers were determined. The administration of unpolished Thai rice significantly and dose dependently decreased the total number of ACF and the percentages of ACF with high-grade dysplasia. Interestingly, unpolished Thai rice suppressed the expression of ${\beta}$-catenin and COX-2. In addition, it also altered proinflammatory (IL-6 and IFN-${\gamma}$) and anti-inflammatory (IL- 10) markers. The results suggested that unpolished Thai rice may provide a promising dietary intake for prevention during precancerous stage of CRC development, through the involvement of ${\beta}$-catenin and COX-2 expression, and also modulate inflammatory cytokines-related to CRC.

• BMB Reports
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• v.50 no.1
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• pp.1-2
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• 2017

Acquiring a selective growth advantage by breaking the proliferation barrier established by gatekeeper genes is a centrally important event in tumor formation. Removal of the mammalian Hippo kinase Mst1 and Mst2 in hepatocytes leads to rapid hepatocellular carcinoma (HCC) formation, indicating that the Hippo signaling pathway is a critical gatekeeper that restrains abnormal growth in hepatocytes. By rigorous genetic approaches, we identified an interacting network of the Hippo, Wnt/${\beta}$-catenin and Notch signaling pathways that control organ size and HCC development. We found that in hepatocytes, the loss of Mst1/2 leads to the activation of Notch signaling, which forms a positive feedback loop with Yap/Taz (transcription factors controlled by Mst1/2). This positive feedback loop results in severe liver enlargement and rapid HCC formation. Blocking the Yap/Taz-Notch positive feedback loop by Notch inhibition in vivo significantly reduced the Yap/Taz activities, hepatocyte proliferation and tumor formation. Furthermore, we uncovered a surprising inhibitory role of Wnt/${\beta}$-catenin signaling to Yap/Taz activities, which are important in tumor initiation. Genetic removal of ${\beta}$-catenin in the liver of the Mst1/2 mutants significantly accelerates tumoriogenesis. Therefore, Wnt/${\beta}$-catenin signaling, known for its oncogenic property, exerts an unexpected function in restricting Yap/Taz and Notch activities in HCC initiation. The molecular interplay between the three signaling pathways identified in our study provides new insights in developing novel therapeutic strategies to treat liver tumors.

• Food Science and Preservation
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• v.24 no.4
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• pp.524-528
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• 2017

Ricinus communis, belongs to the family Euphorbiaceae, has been known as medicinal plants for treatment of inflammation, tumors, antidiabetic, hepatoprotective and laxative. Compared to many pharmacological studies, the effect of R. communis extract on regulating adipogenesis as therapeutic drug for treating obesity has not been reported. R. communis extract (RCE) was investigated to determine its effects on the adipogenesis by monitoring the status of $Wnt/{\beta}-catenin$ signaling and factors involving the differentiation of adipocytes. The differentiation of 3T3-L1 cells monitored by Oil Red O staining was inhibited in concentration dependent manner by RCE. The luciferase activity of HEK 293-TOP cells containing pTOPFlash with Tcf4 response element-luciferase gene was increased approximately 2-folds by the treatment of RCE at concentrations of $100{\mu}g/mL$ compared to the control. Activation of the $Wnt/{\beta}-catenin$ pathway by RCE was further confirmed by immunocytochemical analysis which shows an increment of nuclear localization of ${\beta}-catenin$. In addition, safety of RCE was verified through performing neural stem cell morphology assay. Among the identified flavonoids in RCE, isoquercitrin was the most abundant. Therefore, these results indicate that the adipocyte differentiation was significantly reduced by isoquercitrin in R. communis. In this study, RCE suppresses the adipogenesis of 3T3-L1 cells via the activation of $Wnt/{\beta}-catenin$ signaling.

• Korean Journal of Pharmacognosy
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• v.44 no.4
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• pp.384-390
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• 2013

This study was conducted to evaluate the effect of wheat bran on the promotion of hair growth. When rat vibrissa follicles were treated with n-hexane fraction of wheat bran, the hair-fiber lengths of the vibrissa follicles significantly increased. Moreover, n-hexane fraction of wheat bran was found to significantly induce the telogen-anagen transition in C57BL/6 mice. The fraction increased the proliferation of immortalized vibrissa dermal papilla cells (DPCs) in a dose dependent manner. To elucidate the molecular mechanisms in relation to proliferation of DPCs by the fraction of wheat bran, we examined the expression of cell cycle proteins and wnt/${\beta}$-catenin signaling components. Western blot analysis revealed that the proliferation of DPC by n-hexane fraction of wheat bran was accompanied by increased the level of cyclin D1, cyclin E, phospho-CDK2 and phospho-pRB. In addition, the fraction of wheat bran increased the level of phospho(ser552)-${\beta}$-catenin, phospho(ser675)-${\beta}$-catenin and phospho(ser9)-GSK$3{\beta}$. These results suggest that the hair growing potential of wheat bran mediated by proliferation of DPCs via the regulation of cell cycle proteins and Wnt/${\beta}$-catenin signaling.

• Korean Journal of Pharmacognosy
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• v.47 no.2
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• pp.143-149
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• 2016

Grateloupia elliptica has been reported to have the proliferation effect of dermal papilla cells (DPCs), which play important roles in the regulation of hair cycle. In the present study, we examined in vitro and in vivo hair growth-promoting effect of Grateloupia elliptica. When isolated rat vibrissa follicles were treated with extract of G. elliptica, the hair-fiber lengths of the vibrissa follicles significantly increased. Furthermore, the G. elliptica extract accelerated the telogen-angen transition in C57BL/6 mice. To investigate the molecular mechanisms of the G. elliptica extract on the proliferation of DPCs, we examined the activation of $wnt/{\beta}$-catenin signaling which is known to regulate hair follicle development, differentiation and hair growth. The G. elliptica extract activated $wnt/{\beta}$-catenin signaling via the increase of ${\beta}$-catenin and phospho-$GSK3{\beta}$. In addition, the G. elliptica extract increased the level of cyclin E and CDK2, while the level of $p27^{kip1}$ was decreased. These results suggest that the the G. elliptica extract may induce hair growth by proliferation of DPCs via cell-cycle progression and the activation of $Wnt/{\beta}$-catenin signaling.

• Experimental and Molecular Medicine
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• v.50 no.11
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• pp.12.1-12.12
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• 2018

Drugs targeting the epidermal growth factor receptor (EGFR), such as cetuximab and panitumumab, have been prescribed for metastatic colorectal cancer (CRC), but patients harboring KRAS mutations are insensitive to them and do not have an alternative drug to overcome the problem. The levels of ${\beta}$-catenin, EGFR, and RAS, especially mutant KRAS, are increased in CRC patient tissues due to mutations of adenomatous polyposis coli (APC), which occur in 90% of human CRCs. The increases in these proteins by APC loss synergistically promote tumorigenesis. Therefore, we tested KYA1797K, a recently identified small molecule that degrades both ${\beta}$-catenin and Ras via $GSK3{\beta}$ activation, and its capability to suppress the cetuximab resistance of KRAS-mutated CRC cells. KYA1797K suppressed the growth of tumor xenografts induced by CRC cells as well as tumor organoids derived from CRC patients having both APC and KRAS mutations. Lowering the levels of both ${\beta}$-catenin and RAS as well as EGFR via targeting the $Wnt/{\beta}$-catenin pathway is a therapeutic strategy for controlling CRC and other types of cancer with aberrantly activated the $Wnt/{\beta}$-catenin and EGFR-RAS pathways, including those with resistance to EGFR-targeting drugs attributed to KRAS mutations.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.3
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• pp.1075-1079
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• 2014

MicroRNA expression is a research focus in studies of tumors. This article concentrates attention on potential links between tumors caused by mouse mammary tumor virus (MMTV) and human breast cancer, in order to provide theoretical basis for using mouse model to search for miRNA effects mediated by Wnt/beta-catenin signaling in human breast cancer. By analyzing interactions between miRNAs and the Wnt/beta-catenin signaling pathway in breast cancer, we hope to casts light on more biological functions of miRNAs in the process of tumor formation and growth and to explore their potential value in cancer diagnosis, prognosis and treatment. Our endeavor aimed at providing theoretical basis for finding safer, more effective methods for treatment of human breast cancer at the miRNA molecular level.