• Biomedical Science Letters
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• v.2 no.2
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• pp.175-185
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• 1996

The mitogen-activated protein(MAP) kinase signal transduction pathway represents an important mechanism by which mitogen, such as serum and PMA, regulate cell proliferation and differentiation. Target substrates of the MAP kinase are located within several compartments containing plasma membranes and nucleus. We now report that serum addition induces proliferation of the P388 murine leukemia cell, but PMA does not, while both serum and PMA treatment cause translocation of the MAP kinase, mainly p42$^{mapk}$ isoform, from cytosol into the nucleus, which was monitored by immunoblot analysis using polyclonal anti-ERK1 antibodies. We investigated whether the MAP kinase was capable of phosphorylating c-Jun protein and GST-fusion proteins, the P562$^{kk}$N-terminal peptides (1-77 or 1-123 domain) of the T cell tyrosine kinase, using the partially purified MAP kinase by SP-sephadex C-50, phenyl superose and Mono Q column chromatography. We found that the partially purified MAP kinase was able to phosphorylate c-Jun protein and the GST-fusion protein expressed using E.coli DH5$\alpha$ which is transformed with pGEX-3Xb plasmid vector carrying of p562$^{kk}$N-terminal peptide-encoding DNA. These results imply that tyrosine kinase receptor/Ras/Raf/MAP kinase pathway is a major mechanism for mitogen-induced cell proliferation in P388 murine leukemia cell and that the various MAP kinase isoforms may have their own target substrates located in distinct subcellular compartments.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.5
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• pp.287-293
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• 2009

Cell survival is the result of a balance between programmed cell death and cellular proliferation. Cell membrane receptors and their associated signal transducing proteins control these processes. Of the numerous receptors and signaling proteins, epidermal growth factor receptor (EGFR) is one of the most important receptors involved in signaling pathways implicated in the proliferation and survival of cancer cells. EGFR is often highly expressed in human tumors including oral squamous cell carcinomas, and there is increasing evidence that high expression of EGFR is correlated with poor clinical outcome of common human cancers. Therefore, we examined the antiproliferative activity of gefitinib, epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI), in head and neck cancer cell lines. SCC-9, KB cells were cultured and growth inhibition activity of gefitinib was measured with MTT assay. To study influence of gefitinib in cell cycle, we performed cell cycle analysis with flow cytometry. Western blot was done to elucidate the expression of EGFR in cell lines and phosphorylation of EGFR and downstream kinase protein, Erk and Akt. Significant growth inhibition was observed in SCC-9 cells in contrast with KB cells. Also, flow cytometric analysis showed G1 phase arrest only in SCC-9 cells. In Western blot analysis for investigation of EGFR expression and downstream molecule phosphorylation, gefitinib suppressed phosphorylation of EGFR and downstream protein kinase Erk, Akt in SCC-9. However, in EGFR positive KB cells, weak expression of active form of Erk and Akt and no inhibitory activity of phosphorylation in Erk and Akt was observed. The antiproliferative activity of gefitinib was not correlated with EGFR expression and some possibility of phosphorylation of Erk and Akt as a predictive factor of gefitinib response was emerged. Further investigations on more reliable predictive factor indicating gefitinib response are awaited to be useful gefitinib treatment in head and neck cancer patients.

• Parasites, Hosts and Diseases
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• v.48 no.4
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• pp.285-290
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• 2010

Tyrosine kinases are one of the most important regulators for intracellular signal transduction related to inflammatory responses. However, there are no reports describing the effects of tyrosine kinases on neutrophil apoptosis induced by Entamoeba histolytica, In this study, isolated human neutrophils from peripheral blood were incubated with live trophozoites in the presence or absence of tyrosine kinase inhibitors. Entamoeba-induced receptor shedding of CD16 and PS externalization in neutrophils were inhibited by pre-incubation of neutrophils with the broad-spectrum tyrosine kinase inhibitor genistein or the Src family kinase inhibitor PP2. Entamoeba-induced ROS production was also inhibited by genistein or PP2, Moreover, genistein and PP2 blocked the phosphorylation of ERK and p38 MAPK in neutrophils induced by E. histolytica. These results suggest that Src tyrosine kinases may participate in the signaling event for ROS-dependent activation of MAPKs during neutrophil apoptosis induced by E. histolytica.

• Korean Journal of Clinical Pharmacy
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• v.18 no.2
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• pp.75-83
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• 2008

Purpose: Currently lung cancer ranks second in cancer for incidence rate and is a disease that ranks first for a death rate by cancerous growth because it is already advanced at the time of diagnosis. The purpose of this paper was to analyze the factors that affect the effectiveness of and rash occurrence by Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor (EGFR TKI) in patients with non-small cell lung cancer. Methods: A retrospective chart review of 100 patients, who took EGFR TKI (erlotinib, gefitinib) among patients who were diagnosed with non-small cell lung cancer in a Hospital in Korea between May 2005 and February 2008, was conducted. The drug effectiveness was evaluated by Response Evaluation Criteria In Solid Tumor. Results: EGFR mutation was the only factor associated with drug response (complete response and partial response). When stable disease was added to drug response as the evaluation parameter, ECOG and rash as well as EGFR mutation were found to be important factors. Survival, however, was not affected by EGFR mutation. The factors influenced on survival were older age (${\geq}65$), low ECOG ($1{\sim}2$), adenocarcinoma and rash. In the case of rash, group with EGFR mutation or low ECOG showed significantly higher chance of occurrence. There was no significant difference in rash occurrence between gefitinib and erlotinib groups. Conclusions: Based on the results, EGFR mutation positive and low ECOG ($1{\sim}2$) were significantly important factors for both effectiveness of EGFR TKI and rash occurrence. Also, rash itself was found to be an independently significant factor for the disease control and survival. Therefore, while administering EGFR TKI, patients who have the factors associated with rash occurrence should be closely monitored for effective and safe drug therapy.

• IMMUNE NETWORK
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• v.5 no.3
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• pp.144-149
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• 2005

Background: Fc receptor-mediated phagocytosis is a complex process involving the activation of kinases and phosphatases. FcgammaRIIB has been known to transduces inhibitory signals through an immunoreceptor tyrosine-based inhibitory motif (ITIM) in cytoplasmic domains. In this study, we examined the involvement of inositol-phosphatase in the Fc receptor-mediated phagocytosis. Methods: J774 cells were infected using vaccinia viral vector containing SH2 domain-containing inositol-phosphatase (SHIP) cDNA and stimulated with the sensitized sheep red blood cells. Results: Stimulation of J774 cells induced the tyrosine phosphorylation of SHIP which was maximal at 5 minutes. Phosphatidylinositol-3 (PI-3) kinase inhibitor (wortmannin) inhibits J774 cell phagocytosis of sensitized sheep red blood cells in a dose-dependent manner. Heterologious expression of SHIP in J774 cells inhibits phagocytosis of sensitized sheep red blood cells in a dose-dependency manner, but catalytically dead mutants of SHIP has no effect on phagocytosis. Conclusion: These results strongly suggest that the active signals mediated by PI-3 kinase are opposed by inhibitory signals through SHIP in the regulation of Fc receptor-mediated phagocytosis.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.3187-3190
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• 2013

Background: Epidermal growth factor receptor (EGFR) is a transmembrane receptor which contributes to many processes involved in cell survival, proliferation and inhibits apoptosis, that may lead to cancer development. Gastric cancer is one of the most common diseases of digestive system that has low 5-year-survival. The aim of this research was to determine the significance of EGFR tyrosine kinase domain gene polymorphisms in gastric cancer in Iran. Materials and Methods: In the present study, 83 patients with gastric cancer and 40 normal subjects were investigated for EGFR gene polymorphisms in exons 18-21 by PCR-SSCP. Then, DNA sequencing was conducted for different mobility shift bands. Finally the data were statistically analyzed using the chi-2 test and the SPSSver.16 program. Results: Exon 18 of EGFR gene showed three different bands in SSCP pattern and DNA sequencing displayed one mutation. SSCP pattern of Exons 19 and 21 did not show different migration bands. Exon 20 of EGFR gene revealed multiple migrate bands in SSCP pattern. DNA sequencing displayed 2 mutations in this exon: one mutation was caused amino acid change and another mutation was silent. Conclusion: It may be that EGFR tyrosine kinase gene polymorphisms differ between populations and screening could be useful in gastric cancer patients who might benefit from tyrosine kinase inhibitor therapy.

• Bulletin of the Korean Chemical Society
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• v.25 no.12
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• pp.1801-1806
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• 2004

Ligand-based quantitative structure-activity relationship (QSAR) studies were performed on indolinones derivatives as a potential inhibitor of the protein tyrosine kinase of fibroblast growth factor receptor (FGFR) by comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) implemented in the SYBYL packages. The initial X-ray structure of docked ligand (Su5402) to FGFR was used to minimize the 27 training set molecules using TRIPOS force field. Seven models were generated using CoMFA and CoMSIA with grid spacing 2 ${\AA}$. After the PLS analysis the best predicted CoMSIA model with hydrophobicity, hydrogen bond donor and acceptor property showed that a leave-one out(LOO) cross validated value $({r^2}_{cv})^$ and non-cross validated conventional value $({r^2}_{ncv})^$ are 0.543 and 0.938, respectively.

• The Korean Journal of Physiology and Pharmacology
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• v.27 no.1
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• pp.21-29
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• 2023

The poor outcome of advanced ovarian cancer under conventional therapy necessitates new strategies to improve therapeutic efficacy. β-glucosidase (encoded by GBA) is a lysosomal enzyme and is involved in sphingolipids metabolism. Recent studies revealed that β-glucosidase plays a role in cancer development and chemoresistance. In this work, we systematically evaluated the expression and role of GBA in ovarian cancer. Our work demonstrates that inhibition of β-glucosidase has therapeutic potential for ovarian cancer. Gene Expression Profiling Interactive Analysis database, western blot and immunohistochemistry analyses of patient samples demonstrated that GBA mRNA and protein expression levels were significantly increased in ovarian cancer compared to normal tissues. Functional studies using gainof-function and loss-of-function approaches demonstrated that GBA overexpression did not affect growth and migration but alleviated cisplatin's efficacy in ovarian cancer cells. In addition, GBA depletion resulted in growth inhibition, apoptosis induction, and enhancement of cisplatin's efficacy. Of note, we found that GBA inhibition specifically decreased receptor tyrosine kinase AXL level, leading to the suppression of AXL-mediated signaling pathways. Our data suggest that GBA represents a promising target to inhibit AXL signaling and overcome cisplatin resistance in ovarian cancer.

• Archives of Pharmacal Research
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• v.21 no.2
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• pp.140-146
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• 1998

Hypoglycemic action of brazilin was found to be based on the improvement of peripheral glucose utility, and this action might be correlated with the insulin action pathway. In the present study we investigated the effect of brazilin on the insulin receptor autophosphorylation, protein kinase C (PKC), protein phosphatase and insulin receptor serine kinase in order to confirm whether the hypoglycemic mechanism is concerned with insulin action pathway. Brazilin was found to inhibit PKC and insulin receptor serine kinase, which are involved in the regulation of insulin signal pathway. But any significant effect was not shown on insulin receptor tyrosine kinase activity, autophosphorylation and phosphatase activity. These findings suggest that brazilin might enhance insulin receptor function by decreasing serine phosphorylation, which might mediate hypoglycemic effect of brazilin.

• Natural Product Sciences
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• v.26 no.4
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• pp.345-350
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• 2020

In recent years, tyrosine kinases (TKs) have been the target to combat cancers, and most of the developed inhibitors are of synthetic origin. Natural compounds that have the properties as the TK's inhibitors are very limited. This paper described the isolation of a new dammarane triterpene from the tree bark of Sandoricum koetjape, along with three known related dammaranes from the damar resin of Shorea javanica, as well as their inhibitory properties against eight receptor TKs (RTKs: EGFR, HER2, HER4, IGF1R, InsR, KDR, PDGFRα, and PDGFRβ). Based on the NMR and mass spectral data the new compound was identified as (12β,20S)-12,20-dihydroxy-3,4-seco-dammaran-4,24-dien-3-oic acid (12β-hydroxydammarenolic acid) (1), while the three known compounds were identified as (20S)-20-hydroxy-3,4-seco-dammaran-4,24-dien-3-oic acid (dammarenolic acid) (2), (3β,20S)-3,20-dihydroxydammaran-24-ene (3), and (20S)-3-oxo-20-hydroxydammaran-24-ene (4). The tyrosine kinase assay of the four compounds resulted only 1 and 2 at concentration of 10 μM that had weak activity against EGFR and InsR, with their % inhibitory were 30%, 27% (1), 45%, and 32% (2), respectively. The results suggested that the presence of a linear carboxylic acid group in both compounds could be of significance to the inhibitory properties against the two RTKs.