• Biomedical Science Letters
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• v.13 no.2
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• pp.119-125
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• 2007

It is widely known that protein tyrosine kinases (PTKs) are involved in controlling many biological processes such as cell growth, differentiation, proliferation, survival and apoptosis. An $\alpha3\beta4$ subunit combination acts as a major functional acetylcholine receptor (nAChRs) in male rat major pelvic ganglion (MPG) neurons, and their activation induces fast inward currents and intracellular calcium increases. Recently it has been reported that the activity of acetylcholine receptors (AChRs) in some neurons can be negatively regulated by PTKs. However, the exact mechanism of regulation of nAChRs by PTKs is poorly understood. Therefore, we examined the potential role particular in nAChR by PTK using electrophysiology and calcium imaging in male rat MPG neurons. ACh induced inward currents and $(Ca^{2+})_i$ increases in MPG neurons, concomitantly. These responses were inhibited by more than 90% in $Na^+$- or $Ca^{2+}$- free solution. $\alpha$-conotoxin AuIB, a selective $\alpha3\beta4$ nAChR blocket, inhibited ACh-induced inward currents. Genistein (10 $\mu$M), a broad-spectrum tyrosine kinase inhibitor, markedly decreased ACh-induced currents and $Ca^{2+}$ transients, whereas 10 $\mu$M genistin, an inactive analogue, had little effect. Overall these data suggest that the activities of $\alpha3\beta4$ AChRs in MPG neurons are positively regulated by PTK. In conclusion, trosine kinase may be one of the key factors in the regulation of $\alpha3\beta4$ nAChRs in rat MPG neurons, which may play an important roles in the autonomic neuronal function such as synaptic transmission, autonomic reflex, and neuronal plasticity.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.16
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• pp.6685-6689
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• 2014

Background: Alterations in gene expression levels or mutations of tyrosine kinases are detected in some human cancers. In this study, we examined whether serine threonine tyrosine kinase 1 (STYK1)/novel oncogene with kinase domain (NOK) is overexpressed in patients with colorectal cancer. We also examined the clinical relevance of STYK1/NOK expression in cancer tissues. Materials and Methods: In tumor samples of patients with colorectal cancer and their matched non-cancerous samples, STYK1/NOK messenger RNA (mRNA) expression was analyzed by quantitative reverse transcriptase polymerase chain reaction. Associations between the expression levels of STYK1/NOK and clinicopathological characteristics of colorectal cancer were also assessed using Mann-Whitney U and Kruskal-Wallis tests. Results: Upregulation of STYK1/NOK was found in cancer tissues even at early stage of colorectal cancer compared to normal adjacent tissues. The optimal cutoff point of 0.198 the STYK1/NOK expression showed 0.78 sensitivity and 0.75 specificity for diagnosis. Overexpressed STYK1/NOK was correlated with tumor size but had no association with other clinicopathological characteristics of colorectal cancer. Conclusions: These results indicate that STYK1/NOK mRNA is widely expressed in the patients with colorectal cancer and suggest that inhibition of this molecule could potentially serve as a novel therapeutic target.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.8
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• pp.3801-3804
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• 2014

Background: The prognostic significance of the neutrophil-to-lymphocyte ratio for progression free survival in patients with metastatic renal cell carcinoma is unclear. Materials and Methods: We retrospectively reviewed 45 patients diagnosed with metastatic RCC previously treated with tyrosine kinase inhibitors from two centers, Akdeniz University Hospital and Afyon Kocatepe University. The prognostic value of the pretreatment neutrophil-tolymphocyte ratio, and other clinical and laboratory parameters were assessed by univariate and multivariate analysis. Results: Median progression free survival (PFS) was 13.9 months [95% CI for HR (6.88-20.91)] and overall survival figure of 16.6 months [95% CI for HR (7.23-26.03)] Univariate analysis revealed that PFS was significantly affected by hemoglobin level [p=0.013 (95% CI for HR (0.71-0.96))], eosinophil count [p=0.031 (95% CI for HR (0.20-0.92))], ratio of neutrophil lymphocytes (NLR) [p=0.007 (95% CI for HR (1.47-11.74))] and calcium level [p=0.006 (95% CI for HR (0.15-0.73))]. However, only NLR [p=0.031 (95% CI for HR (1.15-18.1))] and calcium levels [p=0.018 (95% CI for HR (0.20-18.1))] retained significance with multivariate analysis. Median PFS was 23.9 vs 8.6 months in patients with NLR ${\leq}2$ vs NLR >2 (Log rank; p= 0.040). Conclusions: This study showed that increased pretreatment NLR is an independent prognostic factor for patients with metastatic RCC using tyrosine kinase inhibitors.

• Korean Journal of Pharmacognosy
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• v.36 no.4 s.143
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• pp.291-298
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• 2005

Anti-hyperglycemic effects of 17 medicinal plants that have been used for ameliorating diabetes in oriental medicine were evaluated using glucose transport assay in 3T3-L1 adipocytes. Higher activities were obtained by treating water or alcohol extract of Phellodendri Cortex (PC), which showed enhancing effects both on basal and insulin-stimulated glucose uptake. The latter effect of PC was completely inhibited by wortmannin, a specific inhibitor for phosphatidyl inositol 3-kinase (PI 3-kinase), but not affected by SB203580, A specific inhibitor for p38 mitogen-activatedprotein kinase(MAPK). Genistein, an inhibitor for tyrosine kinases, abolished the PC effects completely. Treatment of vanadate, an inhibitor for tyrosine phosphatases, together with PC showed no significant synergic enhancement in glucose uptake. The results of inhibitors associated with insulin signaling pathway indicated that extracts of PC enhance glucose uptake by PI-3 kinase activation which is an upstream event for GLUT4 translocation. Antidiabetic effects of PC extract might be also due to enhanced tyrosine phosphorylation and reduced tyrosine dephosphorylation. In addition, PC accelerated insulin-stimulated glucose uptake in insulin-resistant cells, recovering the uptake level close to that of normal cells. These findings may offer a new way to utilize extracts of PC as novel anti-hyperglycemic agents.

• Journal of Veterinary Clinics
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• v.36 no.6
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• pp.319-324
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• 2019

Receptor tyrosine kinases (RTK) are major promising targets in anticancer therapy in human and veterinary medicine. Using immunohistochemistry method, we evaluated the expressionof five types RTK (PDGFR-α, PDGFR-β, VEGFR 2, c-Kit and Abl) in the six canine brain tumor samples (2 meningioma, 2 astrocytoma, 1 ependymoma and 1 choroid plexus papilloma). A total of five samples expressed PDGFR-β (5/6), one sample, the choroid plexus papilloma, expressed c-Kit (1/6), and a total of two samples expressed Abl (2/6). None of the samples showed expression of PDGFR-α and VEGFR 2. We demonstrate that a significant portion of canine brain tumors express tyrosine receptors for growth factors and show that these receptors generally localize to tumor cell membranes and the cytoplasm. Evaluation of immunohistochemical expression for the RTKs PDGFR-β, c-Kit, and Alb in canine brain samples reveals an interesting potential for molecular targeting by TKIs in therapeutic studies of canine brain tumors, and more studies will be needed to assess the interactions and efficacy of these RTKs and TKIs. Based on these results, we have some evidence for novel chemotherapeutic trials using TKIs for canine nervous tumors.

• Molecules and Cells
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• v.39 no.5
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• pp.389-394
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• 2016

Dovitinib (TKI258) is a small molecule multi-kinase inhibitor currently in clinical phase I/II/III development for the treatment of various types of cancers. This drug has a safe and effective pharmacokinetic/pharmacodynamic profile. Although dovitinib can bind several kinases at nanomolar concentrations, there are no reports relating to osteoporosis or osteoblast differentiation. Herein, we investigated the effect of dovitinib on human recombinant bone morphogenetic protein (BMP)-2-induced osteoblast differentiation in a cell culture model. Dovitinib enhanced the BMP-2-induced alkaline phosphatase (ALP) induction, which is a representative marker of osteoblast differentiation. Dovitinib also stimulated the translocation of phosphorylated Smad1/5/8 into the nucleus and phosphorylation of mitogen-activated protein kinases, including ERK1/2 and p38. In addition, the mRNA expression of BMP-4, BMP-7, ALP, and OCN increased with dovitinib treatment. Our results suggest that dovitinib has a potent stimulating effect on BMP-2-induced osteoblast differentiation and this existing drug has potential for repositioning in the treatment of bone-related disorders.

• YAKHAK HOEJI
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• v.56 no.1
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• pp.26-34
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• 2012

Mast cells play an important role in early and late phase allergic reactions through allergen and IgE-dependent release of histamine, proteases, prostaglandins, and several multifunctional cytokines. In this study, we investigated whether Cudrania tricuspidata extract (CTE) suppresses IgE-mediated allergic responses in mast cells, an allergic animal model, and its mechanism of action in mast cells. We found that CTE inhibited IgE-mediated degranulation and cytokine production in rat basophilic leukemia (RBL)-2H3 mast cells and bone marrow-derived mast cells (BMMC), as well as passive cutaneous anaphylaxis (PCA) in mice. With regard to its mechanism of action, CTE suppressed the activating phosphorylation of spleen tyrosine kinase (Syk), a key enzyme in mast cell signaling processes and that of LAT, a downstream adaptor molecule of Syk in $Fc{\varepsilon}RI$-mediated signal pathways. CTE also suppressed the activating phosphorylation of mitogen-activated protein (MAP) kinases and Akt. The present results strongly suggest that the anti-allergic activity of CTE is mediated through inhibiting degranulation and allergic cytokine secretion by inhibition of Syk kinase in mast cells. Therefore, CTE may be useful for the treatment of allergic diseases.

• Interdisciplinary Bio Central
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• v.4 no.2
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• pp.3.1-3.7
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• 2012

Epidermal growth factor receptor (EGFR) is a member of the ErbB family (ErbB1-4) of receptor tyrosine kinases (RTKs). EGFR controls numerous physiological functions, including cell proliferation, migration, differentiation and survival. Importantly, aberrant signaling by EGFR has been linked to human cancers in which EGFR and its various ligands are frequently overexpressed or mutated. EGFR coordinates activation of multiple downstream factors and is subject of various regulatory processes as it mediates biology of the cell it resides in. Therefore, many studies have been devoted to understanding EGFR biology and targeting the protein for the goal of controlling tumor in clinical settings. Endocytic regulation of EGFR offers a promising area for targeting EGFR activity. Upon ligand binding, the activated receptor undergoes endocytosis and becomes degraded in lysosome, thereby terminating the signal. En route to lysosome, the receptor becomes engaged in activating various signaling pathways including PI-3K, MAPK and Src, and endocytosis may offer both spatial and temporal regulation of downstream target activation. Therefore, endocytosis is an important regulator of EGFR signaling, and increasing emphasis is being placed on endocytosis in terms of cancer treatment and understanding of the disease. In this review, EGFR signaling pathway and its intricate regulation by endocytosis will be discussed.

• Journal of Life Science
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• v.33 no.11
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• pp.859-867
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• 2023

Lupeol is a type of pentacyclic triterpene that has been reported to have therapeutic effects for treating many diseases; however, its effect on insulin resistance is unclear clear. This study examined the inhibitory effect of lupeol on the serine phosphorylation of insulin receptor substrate-1 in insulin resistance-induced 3T3-L1 adipocytes. 3T3-L1 cells were cultured and treated with tumor necrosis factor-α (TNF-α) for 24 hours to induce insulin resistance. Cells treated with different concentrations of lupeol (15 μM or 30 μM) or 100 nM of rosiglitazone were incubated. Then, lysed cells underwent western blotting. Lupeol exhibited a positive effect on the negative regulator of insulin signaling and inflammation-activated protein kinase caused by TNF-α in adipocytes. Lupeol inhibited the activation of protein tyrosine phosphatase-1B (PTP-1B)-a negative regulator of insulin signaling-and c-Jun N-terminal kinase (JNK); it was also an inhibitor of nuclear factor kappa-B kinase (IKK) and inflammation-activated protein kinases. In addition, Lupeol downregulated serine phosphorylation and upregulated tyrosine phosphorylation in insulin receptor substrate-1. Then, the downregulated phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway was activated, the translocation of glucose transporter type 4 was stimulated to the cell membrane, and intracellular glucose uptake increased in the insulin resistance-induced 3T3-L1 adipocytes. Lupeol may improve TNF-α-induced insulin resistance by downregulating the serine phosphorylation of insulin receptor substrate 1 by inhibiting negative regulators of insulin signaling and inflammation-activated protein kinases in 3T3-L1 adipocytes.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.1
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• pp.11-18
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• 1999

Nuclear factor $_{\kappa}B\;(NF-_{\kappa}B)$ activation is modulated by various protein kinases. Activation of $NF-_{\kappa}B$ is known to be important in the regulation of cell viability. The present study investigated the effect of inhibitors of protein tyrosine kinase (PTK), protein kinase C (PKC) and protein kinase A (PKA) on $NF-_{\kappa}B$ activity and the viability of bovine cerebral endothelial cells (BCECs). In serum-deprivation-induced BCEC death, low doses of $TNF{\alpha}$ showed a protective effect. $TNF{\alpha}$ induced $NF-_{\kappa}B$ activation within 4 h in serum-deprivation. PTK inhibitors (herbimycin A and genistein) and PKC inhibitor (calphostin C) prevented $NF-_{\kappa}B$ activation stimulated by $TNF{\alpha}.$ Likewise, these inhibitors prevented the protective effect of $TNF{\alpha}.$ In contrast to $TNF{\alpha}-stimulated\;NF-_{\kappa}B$ activity, basal $NF-_{\kappa}B$ activity of BCECs in media containing serum was suppressed only by calphostin C, but not by herbimycin A. As well BCEC death was also induced only by calphostin C in serum-condition. H 89, a PKA inhibitor, did not affect the basal and $TNF{\alpha}-stimulated\;NF-_{\kappa}B$ activities and the protective effect of $TNF{\alpha}$ on cell death. These data suggest that modulation of $NF-_{\kappa}B$ activation could be a possible mechanism for regulating cell viability by protein kinases in BCECs.