• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1206-1212
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• 2023

The Wnt/β-catenin pathway plays essential roles in regulating various cellular behaviors, including proliferation, survival, and differentiation [1-3]. The intracellular β-catenin level, which is regulated by a proteasomal degradation pathway, is critical to Wnt/β-catenin pathway control [4]. Normally, casein kinase 1 (CK1) and glycogen synthase kinase-3β (GSK-3β), which form a complex with the scaffolding protein Axin and the tumor suppressor protein adenomatous polyposis coli (APC), phosphorylate β-catenin at Ser45, Thr41, Ser37, and Ser33 [5, 6]. Phosphorylated β-catenin is ubiquitinated by the β-transducin repeat-containing protein (β-TrCP), an F-box E3 ubiquitin ligase complex, and ubiquitinated β-catenin is degraded via a proteasome pathway [7, 8]. Colorectal cancer is a significant cause of cancer-related deaths worldwide. Abnormal up-regulation of the Wnt/β-catenin pathway is a major pathological event in intestinal epithelial cells during human colorectal cancer oncogenesis [9]. Genetic mutations in the APC gene are observed in familial adenomatous polyposis coli (FAP) and sporadic colorectal cancers [10]. In addition, mutations in the N-terminal phosphorylation motif of the β-catenin gene were found in patients with colorectal cancer [11]. These mutations cause β-catenin to accumulate in the nucleus, where it forms complexes with transcription factors of the T-cell factor/lymphocyte enhancer factor (TCF/LEF) family to stimulate the expression of β-catenin responsive genes, such as c-Myc and cyclin D1, which leads to colorectal tumorigenesis [12-14]. Therefore, downregulating β-catenin response transcription (CRT) is a potential strategy for preventing and treating colorectal cancer. Plant cytokinins are N⁶-substituted purine derivatives; they promote cell division in plants and regulate developmental pathways. Natural cytokinins are classified as isoprenoid (isopentenyladenine, zeatin, and dihydrozeatin), aromatic (benzyladenine, topolin, and methoxytopolin), or furfural (kinetin and kinetin riboside), depending on their structure [15, 16]. Kinetin riboside was identified in coconut water and is a naturally produced cytokinin that induces apoptosis and exhibits antiproliferative activity in several human cancer cell lines [17]. However, little attention has been paid to kinetin riboside's mode of action. In this study, we show that kinetin riboside exerts its cytotoxic activity against colon cancer cells by suppressing the Wnt/β-catenin pathway and promoting intracellular β-catenin degradation.

• Journal of Microbiology and Biotechnology
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• v.33 no.12
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• pp.1635-1647
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• 2023

Muscle atrophy, which is defined as a decrease in muscle mass and strength, is caused by an imbalance between the anabolism and catabolism of muscle proteins. Thus, modulating the homeostasis between muscle protein synthesis and degradation represents an efficient treatment approach for this condition. In the present study, the protective effects against muscle atrophy of ethanol extracts of Morus alba L. (MA) and Angelica keiskei Koidz. (AK) leaves and their mixtures (MIX) were evaluated in vitro and in vivo. Our results showed that MIX increased 5-aminoimidazole-4-carboxamide ribonucleotide-induced C2C12 myotube thinning, and enhanced soleus and gastrocnemius muscle thickness compared to each extract alone in dexamethasone-induced muscle atrophy Sprague Dawley rats. In addition, although MA and AK substantially improved grip strength and histological changes for dexamethasone-induced muscle atrophy in vivo, the efficacy was superior in the MIX-treated group. Moreover, MIX further increased the expression levels of myogenic factors (MyoD and myogenin) and decreased the expression levels of E3 ubiquitin ligases (atrogin-1 and muscle-specific RING finger protein-1) in vitro and in vivo compared to the MA- and AK-alone treatment groups. Furthermore, MIX increased the levels of phosphorylated phosphoinositide 3-kinase (PI3K), protein kinase B (Akt), and mammalian target of rapamycin (mTOR) that were reduced by dexamethasone, and downregulated the expression of forkhead box O3 (FoxO3a) induced by dexamethasone. These results suggest that MIX has a protective effect against muscle atrophy by enhancing muscle protein anabolism through the activation of the PI3K/Akt/mTOR signaling pathway and attenuating catabolism through the inhibition of FoxO3a.

• Journal of Life Science
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• v.12 no.2
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• pp.164-172
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• 2002

Breast cancer cell lines display a wide variety of growth factor receptors, and considerable evidences implicate the importance of signalings from those receptors. A useful prognostic indicator would be the level of activity of a second messenger protein used in common by these receptors. Our studies were designed to obtain preliminary information on the possible role of polyamine as a mediator of the membrane-associated protein phosphorylation and as a regulator of second messenger in mitogenic signal of estrogen or growth factors in MCF-7 human breast lancer cells. DFMO significantly inhibited the phosphorylation induced by $E_2$, TGF-$\alpha$ and EGF in membrane-associated proteins (154, 134, 116, and 104 kDa). Exogenous polyamines abolished the inhibitory effect of DFMO. Tyrosine phosphorylations of membrane-associated proteins were not increased by $E_2$ or growth factor treatments and not affected DFMO treatment. Polyamine administration markedly enhanced the tyrosine phosphorylation of membrane-associated proteins (154, 134, and 116 kDa). In the present study, $E_2$ and TGF-$\alpha$ and EGF enhanced protein phosphorylation in the almost same levels. These data indicate that $E_2$ and growth factor signaling pathway may cross-talk through various protein kinase which phosphorylated many substrate proteins (154, 134, 116 and 104 kDa). Polyamines may be involved in growth signaling pathway of $E_2$ and TGF-$\alpha$ or EGF for the cross-talk through regulation of the protein phosphorylation such as 154, 134, 116 and 104 kDa. Polyamine may also selectively interfere with several different protein kinases, and the specific steps in signal transduction system were effected by polyamines.

• Tuberculosis and Respiratory Diseases
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• v.44 no.4
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• pp.796-805
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• 1997

Background : It is clear that deregulation of cell cycle progression is a hallmark of neoplastic transformation and genes involved in the $G_1$/S transition of the cell cycle are especially frequent targets for mutations in human cancers, including lung cancer. p16 gene product, one of the G1 cell-cycle related proteins, that is recently identified plays an important role in the negative regulation of the the kinase activity of the cyclin dependent kinase (cdk) enzymes. Therefore p16 gene is known to be an important tumor suppressor gene and is also called MTS1 (multiple tumor suppressor 1). No more oncogenes have been reported to be frequently related to multiple different malignancies than the alterations of p16 gene. Especially when it comes to non-small cell lung cancer, there was no expression of p16 in more than 70% of cell lines examined. And also it is speculated that p16 gene could exert a key role in the development of non-small cell lung cancer. This study was designed to evaluate whether p16 gene could be used as a candidate for gene therapy of non-small cell lung cancer. Methods : After the extraction of total RNA from normal fibroblast cell line and subsequent reverse transcriptase reaction and polymerase chain reaction, the amplified p16 cDNA was subcloned into eukaryotic expression plasmid vector, pRC-CMV. The constructed pRC-CMV-p16 was transfected into the NCI-H441 NSCLC cell line using lipofectin. The changes of G1 cell-cycle related proteins were investigated with Western blot analysis and immunoprecipitation after extraction of proteins from cell lysates and tumor suppressive effect was observed by clonogenic assay. Results : (1) p16(-) NCI-H441 cell line transfected with pRC-CMV-p16 showed the formation of p16 : cdk 4 complex and decreased phosphorylated Rb protein, while control cell line did not. (2) Clonogenic assay demonstrated that the number of colony formation was markedly decreased in p16(-) NCI-H441 cell line transfected with pRC-CMV-p16 than the control cell line. Conclusion : It is confirmed that the expression of p16 protein in p16 absent NSCLC cell line with the gene transfection leads to p16 : cdk4 complex formation, subsequent decrease of phosphorylated pRb protein and ultimately tumor suppressive effects. And also it provides the foundation for the application of p16 gene as a important candidate for the gene therapy of NSCLC.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.11
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• pp.4555-4561
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• 2014

Background: Silencing due to methylation of suppressor of cytokine signaling-3 (SOCS-3), a negative regulator gene for the JAK/STAT signaling pathway has been reported to play important roles in leukemogenesis. Imatinib mesylate is a tyrosine kinase inhibitor that specifically targets the BCR-ABL protein and induces hematological remission in patients with chronic myeloid leukemia (CML). Unfortunately, the majority of CML patients treated with imatinib develop resistance under prolonged therapy. We here investigated the methylation profile of SOCS-3 gene and its downstream effects in a BCR-ABL positive CML cells resistant to imatinib. Materials and Methods: BCR-ABL positive CML cells resistant to imatinib (K562-R) were developed by overexposure of K562 cell lines to the drug. Cytotoxicity was determined by MTS assays and $IC_{50}$ values calculated. Apoptosis assays were performed using annexin V-FITC binding assays and analyzed by flow cytometry. Methylation profiles were investigated using methylation specific PCR and sequencing analysis of SOCS-1 and SOCS-3 genes. Gene expression was assessed by quantitative real-time PCR, and protein expression and phosphorylation of STAT1, 2 and 3 were examined by Western blotting. Results: The $IC_{50}$ for imatinib on K562 was 362nM compared to 3,952nM for K562-R (p=0.001). Percentage of apoptotic cells in K562 increased upto 50% by increasing the concentration of imatinib, in contrast to only 20% in K562-R (p<0.001). A change from non-methylation of the SOCS-3 gene in K562 to complete methylation in K562-R was observed. Gene expression revealed down-regulation of both SOCS-1 and SOCS-3 genes in resistant cells. STAT3 was phosphorylated in K562-R but not K562. Conclusions: Development of cells resistant to imatinib is feasible by overexposure of the drug to the cells. Activation of STAT3 protein leads to uncontrolled cell proliferation in imatinib resistant BCR-ABL due to DNA methylation of the SOCS-3 gene. Thus SOCS-3 provides a suitable candidate for mechanisms underlying the development of imatinib resistant in CML patients.

• Nutrition Research and Practice
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• v.8 no.6
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• pp.655-661
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• 2014

BACKGROUND/OBJECTIVES: The purpose of this study was to examine the effects and associated mechanisms of arctiin, a lignan compound found in burdock, on adipogenesis in 3T3-L1 cells. Also, the effects of arctiin supplementation in obese mice fed a high-fat diet on adiposity were examined. MATERIALS/METHODS: 3T3-L1 cells were treated with arctiin (12.5 to $100{\mu}M$) during differentiation for 8 days. The accumulation of lipid droplets was determined by Oil Red O staining and intracellular triglyceride contents. The expressions of genes related to adipogenesis were measured by real-time RT-PCR and Western blot analyses. For in vivo study, C57BL/6J mice were first fed either a control diet (CON) or high-fat diet (HF) to induce obesity, and then fed CON, HF, or HF with 500 mg/kg BW arctiin (HF + AC) for four weeks. RESULTS: Arctiin treatment to 3T3-L1 pre-adipocytes markedly decreased adipogenesis in a dose-dependent manner. The arctiin treatment significantly decreased the protein levels of the key adipogenic regulators $PPAR{\gamma}$ and $C/EBP{\alpha}$, and also significantly inhibited the expression of SREBP-1c, fatty acid synthase, fatty acid-binding protein and lipoprotein lipase. Also, arctiin greatly increased the phosphorylation of AMP-activated protein kinase (AMPK) and its downstream target phosphorylated-acetyl CoA carboxylase. Furthermore, administration of arctiin significantly decreased the body weight in obese mice fed with the high-fat diet. The epididymal, perirenal or total visceral adipose tissue weights of mice were all significantly lower in the HF + AC than in the HF. Arctiin administration also decreased the sizes of lipid droplets in the epididymal adipose tissue. CONCLUSIONS: Arctiin inhibited adipogenesis in 3T3-L1 adipocytes through the inhibition of $PPAR{\gamma}$ and $C/EBP{\alpha}$ and the activation of AMPK signaling pathways. These findings suggest that arctiin has a potential benefit in preventing obesity.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.4
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• pp.361-370
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• 2017

Previous reports have suggested that physical and psychological stresses may trigger fibromyalgia (FM). Stress is an important risk factor in the development of depression and memory impairments. Antidepressants have been used to prevent stress-induced abnormal pain sensation. Among various antidepressants, tianeptine has been reported to be able to prevent neurodegeneration due to chronic stress and reverse decreases in hippocampal volume. To assess the possible effect of tianeptine on FM symptoms, we constructed a FM animal model induced by restraint stress with intermittent cold stress. All mice underwent nociceptive assays using electronic von Frey anesthesiometer and Hargreaves equipment. To assess the relationship between tianeptine and expression levels of brain-derived neurotrophic factor (BDNF), cAMP response element-binding protein (CREB), and phosphorylated cAMP response element-binding protein (p-CREB), western blotting and immunohistochemistry analyses were performed. In behavioral analysis, nociception tests showed that pain threshold was significantly decreased in the FM group compared to that in the control group. Western blot and immunohistochemical analyses of medial prefrontal cortex (mPFC) and hippocampus showed downregulation of BDNF and p-CREB proteins in the FM group compared to the control group. However, tianeptine recovered these changes in behavioral tests and protein level. Therefore, this FM animal model might be useful for investigating mechanisms linking BDNF-CREB pathway and pain. Our results suggest that tianeptine might potentially have therapeutic efficacy for FM.

• Journal of Life Science
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• v.24 no.10
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• pp.1144-1150
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• 2014

The eIF4E protein is the key regulator of translation initiation. The interaction of eIF4E with eIF4G triggers the translation of mRNA, and several proteins interrupt this association to modulate translation. Human 4E-T is one of the eIF4E-binding partners that represses the translation of bound mRNAs, and it is involved in the transport of eIF4E to processing bodies (P-bodies). Although Clast4, the mouse homolog of human 4E-T, might play critical roles in the regulation of translation, its properties are not well known. In this report, we deciphered the properties of Clast4 by determining its phosphorylation state, binding to eIF4E, and effects of overexpression on cell proliferation. Clast4 was phosphorylated by protein kinase A (PKA) in vivo on several residues of its amino terminus. Nevertheless, the PKA phosphorylation of Clast4 appeared to have no effect on either its eIF4E-binding ability or localization. Clast4 interacted with eIF4E1 and CPEB. The conserved eIF4E-binding sequence in Clast4, $YXXXXL_{\phi}$, was important for binding eIF4E1A but not eIF4E1B. Similar to that of another well-known eIF4E regulator, the eIF4E binding protein (4E-BP), the overexpression of Clast4 decreased cell proliferation. These results suggest that Clast4 acts as a global translation regulator in cells.

• Biomolecules & Therapeutics
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• v.28 no.6
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• pp.561-568
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• 2020

We examined the anticancer effects of a novel sirtuin inhibitor, MHY2256, on HCT116 human colorectal cancer cells to investigate its underlying molecular mechanisms. MHY2256 significantly suppressed the activity of sirtuin 1 and expression levels of sirtuin 1/2 and stimulated acetylation of forkhead box O1, which is a target protein of sirtuin 1. Treatment with MHY2256 inhibited the growth of the HCT116 (TP53 wild-type), HT-29 (TP53 mutant), and DLD-1 (TP53 mutant) human colorectal cancer cell lines. In addition, MHY2256 induced G0/G1 phase arrest of the cell cycle progression, which was accompanied by the reduction of cyclin D1 and cyclin E and the decrease of cyclin-dependent kinase 2, cyclin-dependent kinase 4, cyclin-dependent kinase 6, phosphorylated retinoblastoma protein, and E2F transcription factor 1. Apoptosis induction was shown by DNA fragmentation and increase in late apoptosis, which were detected using flow cytometric analysis. MHY2256 downregulated expression levels of procaspase-8, -9, and -3 and led to subsequent poly(ADP-ribose) polymerase cleavage. MHY2256-induced apoptosis was involved in the activation of caspase-8, -9, and -3 and was prevented by pretreatment with Z-VAD-FMK, a pan-caspase inhibitor. Furthermore, the autophagic effects of MHY2256 were observed as cytoplasmic vacuolation, green fluorescent protein-light-chain 3 punctate dots, accumulation of acidic vesicular organelles, and upregulated expression level of light-chain 3-II. Taken together, these results suggest that MHY2256 could be a potential novel sirtuin inhibitor for the chemoprevention or treatment of colorectal cancer or both.

• Journal of Ginseng Research
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• v.40 no.2
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• pp.135-140
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• 2016

Background: Nephrotoxicity is a common side effect of medications. Panax ginseng is one of the best-known herbal medicines, and its individual constituents enhance renal function. Identification of its efficacy and mechanisms of action against drug-induced nephrotoxicity, as well as the specific constituents mediating this effect, have recently emerged as an interesting research area focusing on the kidney protective efficacy of P. ginseng. Methods: The present study investigated the kidney protective effect of fermented black ginseng (FBG) and its active component ginsenoside 20(S)-Rg3 against cisplatin (chemotherapy drug)-induced damage in pig kidney (LLC-PK1) cells. It focused on assessing the role of mitogen-activated protein kinases as important mechanistic elements in kidney protection. Results: The reduced cell viability induced by cisplatin was significantly recovered with FBG extract and ginsenoside 20(S)-Rg3 dose-dependently. The cisplatin-induced elevated protein levels of phosphorylated c-Jun N-terminal kinase (JNK), p53, and cleaved caspase-3 were decreased after cotreatment with FBG extract or ginsenoside 20(S)-Rg3. The elevated percentage of apoptotic LLC-PK1 cells induced by cisplatin treatment was significantly abrogated by cotreatment with FBG and the ginsenoside 20(S)-Rg3. Conclusion: FBG and its major ginsenoside 20(S)-Rg3, ameliorated cisplatin-induced nephrotoxicity in LLC-PK1 cells by blocking the JNKep53ecaspase-3 signaling cascade.