• Molecules and Cells
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• 제27권4호
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• pp.403-408
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• 2009

Skeletal muscle regeneration is a highly orchestrated process initiated by activation of adult muscle satellite cells. Upon muscle injury, the inflammatory process is always accompanied by muscle regeneration. Leukotriene $B_4$ is one of the essential inflammatory mediators. We isolated and cultured primary satellite cells. RT-PCR showed that myoblasts expressed mRNA for $LTB_4$ receptors BLT1 and BLT2, and $LTB_4$ promoted myoblast proliferation and fusion. Quantitative real-time PCR and immunoblotting showed that $LTB_4$ treatment expedited the expression process of differentiation markers MyoD and M-cadherin. U-75302, a specific BLT1 inhibitor, but not LY2552833, a specific BLT2 inhibitor, blocked proliferation and differentiation of myoblasts induced by $LTB_4$, which implies the involvement of the BLT1 pathway. Overall, the data suggest that $LTB_4$ contributes to muscle regeneration by accelerating proliferation and differentiation of satellite cells.

• Current Research on Agriculture and Life Sciences
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• 제32권4호
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• pp.199-202
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• 2014

The bioconversion of cellulosic biomass hydrolyzates consisting mainly of glucose and xylose requires the use of engineered Saccharomyces cerevisiae expressing a heterologous xylose pathway. However, there is concern that a fungal xylose pathway consisting of NADPH-specific xylose reductase (XR) and $NAD^+$-specific xylitol dehydrogenase (XDH) may result in a cellular redox imbalance. However, the glycerol biosynthesis and glycerol degradation pathways of S. cerevisiae, termed here as the glycerol cycle, has the potential to balance the cofactor requirements for xylose metabolism, as it produces NADPH by consuming NADH at the expense of one mole of ATP. Therefore, this study tested if the glycerol cycle could improve the xylose metabolism of engineered S. cerevisiae by cofactor balancing, as predicted by an in-silico analysis using elementary flux mode (EFM). When the GPD1 gene, the first step of the glycerol cycle, was overexpressed in the XR/XDH-expressing S. cerevisiae, the glycerol production significantly increased, while the xylitol and ethanol yields became negligible. The reduced xylitol yield suggests that enough $NAD^+$ was supplied for XDH by the glycerol cycle. However, the GPD1 overexpression completely shifted the carbon flux from ethanol to glycerol. Thus, moderate expression of GPD1 may be necessary to achieve improved ethanol production through the cofactor balancing.

• Molecules and Cells
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• 제44권8호
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• pp.613-622
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• 2021

In vertebrate eyes, the retinal pigment epithelium (RPE) provides structural and functional homeostasis to the retina. The RPE takes up retinol (ROL) to be dehydrogenated and isomerized to 11-cis-retinaldehyde (11-cis-RAL), which is a functional photopigment in mammalian photoreceptors. As excessive ROL is toxic, the RPE must also establish mechanisms to protect against ROL toxicity. Here, we found that the levels of retinol dehydrogenases (RDHs) are commonly decreased in phosphatase tensin homolog (Pten)-deficient mouse RPE, which degenerates due to elevated ROL and that can be rescued by feeding a ROL-free diet. We also identified that RDH gene expression is regulated by forkhead box O (FOXO) transcription factors, which are inactivated by hyperactive Akt in the Pten-deficient mouse RPE. Together, our findings suggest that a homeostatic pathway comprising PTEN, FOXO, and RDH can protect the RPE from ROL toxicity.

• Molecules and Cells
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• 제46권7호
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• pp.430-440
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• 2023

Linear ubiquitin chain assembly complex (LUBAC) is a ubiquitin E3 ligase complex composed of HOIP, HOIL-1L, and SHARPIN that catalyzes the formation of linear/M1-linked ubiquitin chain. It has been shown to play a pivotal role in the nuclear factor (NF)-κB signaling induced by proinflammatory stimuli. Here, we found that tumor susceptibility gene (TSG101) physically interacts with HOIP, a catalytic component of LUBAC, and potentiates LUBAC activity. Depletion of TSG101 expression by RNA interference decreased TNFα-induced linear ubiquitination and the formation of TNFα receptor 1 signaling complex (TNF-RSC). Furthermore, TSG101 facilitated the TNFα-induced stimulation of the NF-κB pathway. Thus, we suggest that TSG101 functions as a positive modulator of HOIP that mediates TNFα-induced NF-κB signaling pathway.

• Asian Pacific Journal of Cancer Prevention
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• 제15권4호
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• pp.1711-1714
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• 2014

Objective: To explore the effect of Withaferin A on A549 cellular proliferation and apoptosis in non-small cell lung cancer (NSCLC). Materials and Methods: NSCLC cell line A549 was selected to explore the effect of Withaferin A on A549 cellular proliferation, apoptosis and the PI3K/Akt signal pathway capable of regulating tumor biological behavior by assessment of cellular proliferation, cellular apoptotic rates and cellular cycling as well as by immuno-blotting. Results: Withaferin A could inhibit A549 cellular proliferation and the control rate was dosage-dependent (P<0.05), which also increased time-dependently with the same dosage of Withaferin A (P<0.05). The apoptotic indexes in A549 cells treated with 0, 2.5, 5.0, 10.0 and 20.0 ${\mu}mol{\cdot}L^{-1}$ Withaferin A for 48 h were significantly different (P<0.05). In addition, the apoptotic rates of each group in both early and advanced stages were higher than those in 0 ${\mu}mol{\cdot}L^{-1}$ (P<0.05), which were evidently higher after 48 h than those after 24 h (P<0.05). A549 cells treated by Withaferin A for 48 h were markedly lower in Bcl-2 level and obviously higher in Bax and cleaved caspase-3 levels than those treated by 0 ${\mu}mol{\cdot}L^{-1}$ Withaferin A (P<0.05), and there were significant differences among 5, 10 and 20 ${\mu}mol{\cdot}L^{-1}$ Withaferin A (P<0.05). The ratios of A549 cells treated by Withaferin A for 48 h in G0/G1 stage were higher than those in 0 ${\mu}mol{\cdot}L^{-1}$, while those in S and G2/M stages were obviously lower than those in G2/M stage, and there were significant differences in 5.0, 10.0 and 20.0 ${\mu}mol{\cdot}L^{-1}$ Withaferin A (P<0.05). Additionally, p-Akt/Akt values were in reverse association with dosage, and the differences were significant (P<0.05). Conclusion: Withaferin A can inhibit the proliferation and apoptosis of A549 cells by suppressing activation of the PI3K/Akt pathways.

• Asian Pacific Journal of Cancer Prevention
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• 제14권9호
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• pp.5317-5323
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• 2013

Breast cancer is the most prevalent cancer and one of the leading causes of death among women in the world. Plants and herbs may play an important role in complementary or alternative treatment. The aim of this study was to evaluate the antioxidant and anti-proliferative potential of Urtica dioica. The anti oxidant activity of an aqueous extract of Urtica dioica leaf was measured by MTT assay and the FRAP method while its anti-proliferative activity on the human breast cancer cell line (MCF-7) and fibroblasts isolated from foreskin tissue was evaluated using MTT assay. Mechanisms leading to apoptosis were also investigated at the molecular level by measuring the amount of anti and pro-apoptotic proteins and at the cellular level by studying DNA fragmentation and annexin V staining by flow cytometry. The aqueous extract of Urtica dioica showed antioxidant effects with a correlation coefficient of $r^2$=0.997. Dose-dependent and anti-proliferative effects of the extract were observed only on MCF-7 cells after 72 hrs with an $IC_{50}$ value of 2 mg/ml. This anti proliferative activity was associated with an increase of apoptosis as demonstrated by DNA fragmentation, the appearance of apoptotic cells in flow cytometry analysis and an increase of the amount of calpain 1, calpastatin, caspase 3, caspase 9, Bax and Bcl-2, all proteins involved in the apoptotic pathway. This is the first time such in vitro antiproliferative effect of aqueous extract of Urtica dioica leaf has been described for a breast cancer cell line. Our findings warrant further research on Urtica dioica as a potential chemotherapeutic agent for breast cancer.

• Molecules and Cells
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• 제42권6호
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• pp.448-459
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• 2019

The phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway is a promising target for gastric cancer (GC) treatment; however the efficacy of PI3K/mTOR dual inhibitors in GC has not yet been maximized. Additionally, the effect of autophagy regulation by PI3K/mTOR dual inhibitors has not been clearly elucidated in GC treatment. We aimed to show that our newly developed PI3K/mTOR dual inhibitor, CMG002, when combined with an autophagy inhibitor, chloroquine (CQ), potently induces effective cancer cell death in Epstein-Barr virus (EBV)-associated gastric cancer (EBVaGC) cells, where both the PI3K/AKT/mTOR and autophagy pathways play important roles in disease pathogenesis. EBV- and mock-infected AGS and NUGC3 GC cell lines were treated with CMG002 +/- CQ. PI3K/AKT/mTOR signaling pathway mediators, cellular apoptosis and autophagy markers were confirmed by Western blot assay. Cell viability was assessed using the Cell Counting Kit-8 (CCK-8) assay. CMG002 effectively blocked the PI3K/AKT/mTOR pathway by markedly decreasing phosphorylation of AKT and its downstream mediator S6. CMG002 induced G0/G1 cell cycle arrest and enhanced apoptotic cell death in AGS and NUGC3 cells, particularly EBV-infected cells compared with mock-infected cells, as confirmed by flow cytometric analyses and TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assays. The combination of CMG002 plus CQ synergistically increased apoptotic cell death in EBV-infected GC cell lines when compared with CMG002 alone (P < 0.05). Our results suggest that the new PI3K/mTOR dual inhibitor, CMG002, when used in combination with the autophagy inhibitor, CQ, provides enhanced therapeutic efficacy against EBVaGC.

• Biomolecules & Therapeutics
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• 제31권1호
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• pp.73-81
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• 2023

Sirtuins (SIRTs) belong to the nicotinamide adenine dinucleotide (NAD+)-dependent class III histone deacetylase family. They are key regulators of cellular and physiological processes, such as cell survival, senescence, differentiation, DNA damage and stress response, cellular metabolism, and aging. SIRTs also influence carcinogenesis, making them potential targets for anticancer therapeutic strategies. In this study, we investigated the anticancer properties and underlying molecular mechanisms of a novel SIRT1 inhibitor, MHY2251, in human colorectal cancer (CRC) cells. MHY2251 reduced the viability of various human CRC cell lines, especially those with wild-type TP53. MHY2251 inhibited SIRT1 activity and SIRT1/2 protein expression, while promoting p53 acetylation, which is a target of SIRT1 in HCT116 cells. MHY2251 treatment triggered apoptosis in HCT116 cells. It increased the percentage of late apoptotic cells and the sub-G1 fraction (as detected by flow cytometric analysis) and induced DNA fragmentation. In addition, MHY2251 upregulated the expression of FasL and Fas, altered the ratio of Bax/Bcl-2, downregulated the levels of pro-caspase-8, -9, and -3 proteins, and induced subsequent poly(ADP-ribose) polymerase cleavage. The induction of apoptosis by MHY2251 was related to the activation of the caspase cascade, which was significantly attenuated by pre-treatment with Z-VAD-FMK, a pan-caspase inhibitor. Furthermore, MHY2251 stimulated the phosphorylation of c-Jun N-terminal kinase (JNK), and MHY2251-triggered apoptosis was blocked by pre-treatment with SP600125, a JNK inhibitor. This finding indicated the specific involvement of JNK in MHY2251-induced apoptosis. MHY2251 shows considerable potential as a therapeutic agent for targeting human CRC via the inhibition of SIRT1 and activation of JNK/p53 pathway.

• Molecules and Cells
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• 제46권10호
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• pp.592-610
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• 2023

The Hippo kinase cascade functions as a central hub that relays input from the "outside world" of the cell and translates it into specific cellular responses by regulating the activity of Yes-associated protein 1 (YAP1). How Hippo translates input from the extracellular signals into specific intracellular responses remains unclear. Here, we show that transforming growth factor β (TGFβ)-activated TAK1 activates LATS1/2, which then phosphorylates YAP1. Phosphorylated YAP1 (p-YAP1) associates with RUNX3, but not with TEAD4, to form a TGFβ-stimulated restriction (R)-point-associated complex which activates target chromatin loci in the nucleus. Soon after, p-YAP1 is exported to the cytoplasm. Attenuation of TGFβ signaling results in re-localization of unphosphorylated YAP1 to the nucleus, where it forms a YAP1/TEAD4/SMAD3/AP1/p300 complex. The TGFβ-stimulated spatiotemporal dynamics of YAP1 are abrogated in many cancer cells. These results identify a new pathway that integrates TGFβ signals and the Hippo pathway (TGFβ→TAK1→LATS1/2→YAP1 cascade) with a novel dynamic nuclear role for p-YAP1.

• BMB Reports
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• 제49권6호
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• pp.305-310
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• 2016

Toll-like receptors (TLRs) play a critical role in the innate immune response against pathogens. Each TLR recognizes specific pathogen-associated molecular patterns, after which they activate the adaptor protein MyD88 or TRIF-assembled signaling complex to produce immune mediators, including inflammatory cytokines and type I IFNs. Although the activation of TLR is important for host defense, its uncontrolled activation can damage the host. During the past decade, numerous studies have demonstrated that GSK3β is a key regulator of inflammatory cytokine production in MyD88-mediated TLR signaling via TLR2 and TLR4. Recently, GSK3β has also been implicated in the TRIF-dependent signaling pathway via TLR3. In this review, we describe current advances on the regulatory role of GSK3β in immune responses associated with various TLRs. A better understanding of the role of GSK3β in TLR signaling might lead to more effective anti-inflammatory interventions.