• Journal of Life Science
• /
• v.26 no.7
• /
• pp.826-834
• /
• 2016

The present investigation was undertaken to examine the effectiveness of the combination treatment of an Hsp90 inhibitor and a SIRT1 inhibitor on suppressing the growth of chemo-resistant human cancer cells. We showed that inhibition of SIRT1 effectively potentiated the cytotoxicity of 17-allylamino-17-demethoxygeldanamycin (17-AAG) and reversed Hsp90 inhibitor resistance in multidrug-resistant (MDR) human ovarian HeyA8-MDR cells. Amurensin G, a potent natural SIRT1 inhibitor, enhanced Hsp90 inhibitor-mediated abrogation of the Hsp90 chaperone function and accelerated degradation of mutated p53 (mut p53), an Hsp90 client protein, by up-regulation of ubiquitin ligase CHIP. Knock-down of CHIP significantly attenuated amurensin G-induced mut p53 degradation. Down-regulation of mut p53 reduced the expression of heat shock factor1 (HSF1)/heat shock proteins (Hsps), a major cause of Hsp90 inhibitor resistance, which led to sensitization of the MDR cells to the Hsp90 inhibitor by the SIRT1 inhibitor. Amurensin G potentiated cytotoxicity of the Hsp90 inhibitor in HeyA8-MDR cells through suppression of 17-AAG-induced Hsp70 and Hsp27 induction via down-regulation of mut p53/HSF1, and it caused activation of PARP and inhibition of Bcl-2. Our data suggests that SIRT1 inhibitors could be used to sensitize MDR cells to Hsp90 inhibitors, possibly through suppression of the mut p53/HSF1-dependent pathway, and a novel mut p53-directed action of SIRT1 inhibition could effectively prevent mut p53 accumulation in MDR cells.

• Molecules and Cells
• /
• v.21 no.1
• /
• pp.42-51
• /
• 2006

We investigated the mechanism of contraction induced by S1P in esophageal smooth muscle cells. Western blot analysis demonstrated that $S1P_1$, $S1P_2$, $S1P_3$, and $S1P_5$ receptors existed in the cat esophagus. Only penetration of EDG-5 ($S1P_2$) antibody into permeabilized cells inhibited S1P-induced contraction. Pertussis toxin (PTX) also inhibited contraction, suggesting that it was mediated by $S1P_2$ receptors coupled to a PTXsensitive $G_i$ protein. Specific antibodies to $G_{i2}$, $G_q$ and $G_{\beta}$ inhibited contraction, implying that the S1P-induced contraction depends on PTX-insensitive $G_q$ and $G_{\beta}$ dimers as well as the PTX-sensitive $G_{i2}$. Contraction was not affected by the phospholipase $A_2$ inhibitor DEDA, or the PLD inhibitor ${\rho}$-chloromercuribenzoate, but it was abolished by the PLC inhibitor U73122. Incubation of permeabilized cells with $PLC{\beta}3$ antibody also inhibited contraction. Contraction involved the activation of a PKC pathway since it was affected by GF109203X and chelerythrine. Since $PKC{\varepsilon}$ antibody inhibited contraction, $PKC{\varepsilon}$ may be required. Preincubation of the muscle cells with the MEK inhibitor PD98059 blocked S1P-induced contraction, but the p38 MAP kinase inhibitor SB202190 did not. In addition, co-treatment of cells with GF 109203X and PD98059 did not have a synergistic effect, suggesting that these two kinases are involved in the same signaling pathway. Our data suggest that S1P-induced contraction in esophageal smooth muscle cells is mediated by $S1P_2$ receptors coupled to PTX-sensitive $G_{i2}$ proteins, and PTX-insensitive $G_q$ and $G_{\beta}$ proteins, and that the resulting activation of the $PLC{\beta}3$ and $PKC{\varepsilon}$ pathway leads to activation of a p44/p42 MAPK pathway.

• Journal of Life Science
• /
• v.19 no.7
• /
• pp.871-877
• /
• 2009

We investigated the effects of sodium butyrate, a histone deacetylase inhibitor, on the cell cycle progression in human monocytic leukemia U937 cells. Exposure of U937 cells to sodium butyrate resulted in growth inhibition, G1 arrest of the cell cycle and induction of apoptosis in a dose-dependent manner as measured by MTT assay and flow cytometry analysis. The increase in G1 arrest was associated with the down-regulation in cyclin D1, E, A, cyclin-dependent kinase (Cdk) 4 and 6 expression, and up-regulation of Cdk inhibitors such as p21 and p27. Sodium butyrate treatment also inhibited the phosphorylation of retinoblastoma protein (pRB) and p130, however, the levels of transcription factors E2F-1 and E2F-4 were not markedly modulated. Furthermore, the down-regulation of phosphorylation of pRB and p130 by this compound was associated with enhanced binding of pRB and E2F-1, as well as p130 and E2F-4, respectively. Overall, the present results demonstrate a combined mechanism involving the inhibition of pRBjp130 phosphorylation and induction of Cdk inhibitors as targets for sodium butyrate that may explain some of its anti-cancer effects in U937 cells.

• Microbiology and Biotechnology Letters
• /
• v.20 no.5
• /
• pp.534-542
• /
• 1992

Trypsin inhibtor produced by Streptomyces sp. S-217 was purified by solvent extraction and various column chromatographies. and physico-chemical properties of the inhibitor were investigated. Inhibitor complex was formed for incubation of 10 min. Streptomyces 5-217 showed the highest production of trypsin inhibitor when it was cultivated at $37^{\circ}C$ for 66 hr in the medium containing 2% mannitol & 0.9% peptone, pH 7.0. Trypsin inhibitor was purified by column chromatography and high performance liquid chromatography. Trypsin inhibitor indicated the maxium wavelength at 215 nm and solubilities in water, methanol and dimethyl sulfoxide were 95, 70 and 75%, respectively. The concentration of 50% inhibition ($IC^{50}$) was 15 $\mu$g/ml. The inhibitor was stable on heating at $100^{\circ}C$ for 60 min in pH 5~9 and was more stable in alkaline region than acidic region.

• Asian-Australasian Journal of Animal Sciences
• /
• v.4 no.3
• /
• pp.285-291
• /
• 1991

Two experiments were conducted to evaluate the effect of mold inhibitor in the ration which had two different protein levels (18% and 12%) and two different particle sizes (80 or 40% of the particles in the ration less than 1.19 mm). The experimental diets with ave. 12.7% moisture which were treated at the level of 0.1% mold inhibitor were stored under 85% humidity and at $29{\pm}1^{\circ}C$ for 10 to 40 days. In experiment 1, after 40 days of storage the $CO_2$ production in the feed treated with mold inhibitor was higher (p < 0.01) than when 40% of the ration's panicle size was 1.19 mm. Aflatoxin production in the experimental diet with mold inhibitor was affected (p<0.05) by the levels of protein and the different particle size ranges after 40 days storage. The interaction of protein levels and particle size ranges on the anatoxin and $CO_2$ production was significant (p<0.05) at 40 days storage. In experiment 2, there was a decrease in total body weight gain and total feed intake observed in chicks fed the untreated diet of 18% protein with 40% of the particles in the ration less than 1.19 mm stored for 40 days. Feed conversion was depressed (p<0.05) in the chicks fed the untreated diets of both particle sizes. Particle size X types of feed interaction in feed conversion was significant (p<0.05).

• Microbiology and Biotechnology Letters
• /
• v.23 no.5
• /
• pp.602-608
• /
• 1995

The aim of the present research program was to construct an optimum fermentation system and to characterize the properties of cathepsin B inhibitor from Streptomyces chromofuscus SMF28. Glucose and casitone were proved to be good carbon source and nitrogen source, respectively. The production of inhibitor was high at lower concentration than 10 mM of inorganic phosphate. The optimum temperature and pH for the production of inhibitor were 30$\circ$C and pH 7, respectively. The production of inhibitor was related to mycelial growth and was affected by medium composition. The inhibitor in culture filtrate of S. chromofuscus SMF28 was purified by butanol extraction, silica gel chromatography, Amberlite IRC-50 (H$^{+}$ form) chromatography, preparative TLC, and preparative HPLC. From amino acid analysis and UV, IR, $^{1}$H-NMR spectroscopic analysis, the inhibitor was identified as a peptide containing valine and phenylalanine derivative.

• The Korean Journal of Physiology and Pharmacology
• /
• v.20 no.2
• /
• pp.161-168
• /
• 2016

Abnormal localization of tumor suppressor proteins is a common feature of renal cancer. Nuclear export of these tumor suppressor proteins is mediated by chromosome region maintenance-1 (CRM1). Here, we investigated the antitumor effects of a novel reversible inhibitor of CRM1 on renal cancer cells. We found that S109 inhibits the CRM1-mediated nuclear export of RanBP1 and reduces protein levels of CRM1. Furthermore, the inhibitory effects of S109 on CRM1 is reversible. Our data demonstrated that S109 significantly inhibits proliferation and colony formation of renal cancer cells. Cell cycle assay showed that S109 induced G1-phase arrest, followed by the reduction of Cyclin D1 and increased expression of p53 and p21. We also found that S109 induces nuclear accumulation of tumor suppressor proteins, Foxo1 and p27. Most importantly, mutation of CRM1 at Cys528 position abolished the effects of S109. Taken together, our results indicate that CRM1 is a therapeutic target in renal cancer and the novel reversible CRM1 inhibitor S109 can act as a promising candidate for renal cancer therapy.

• Biomedical Science Letters
• /
• v.22 no.2
• /
• pp.60-64
• /
• 2016

In the pathogenesis of inflammatory diseases such as allergies, S100A8 acts as an important molecule and T lymphocytes are essential cytokine-releasing cells. In this study, we investigated the effect of S100A8 on release of cytokines, specifically MCP-1, IL-6, and IL-8 in T cells, and its associated signaling mechanism. S100A8 increased secretion of MCP-1, IL-6, and IL-8 in a time- and dose-dependent manner. Elevated secretion of MCP-1, IL-6, and IL-8 due to S100A8 was inhibited by the TLR4 inhibitor TLR4i, the PI3K inhibitor LY294002, the $PKC{\delta}$ inhibitor rottlerin, the ERK inhibitor PD98059, the p38 MAPK inhibitor SB202190, the JNK inhibitor SP600125, and the NF-${\kappa}B$ inhibitor BAY-11-7085. S100A8 induced phosphorylation of ERK, p38 MAPK, and JNK in a time-dependent manner, and activation was suppressed by TLR4i, LY294002, and rottlerin. S100A8 induced NF-${\kappa}B$ activation by $I{\kappa}-B{\alpha}$ degradation, and NF-${\kappa}B$ activity was suppressed by PD98059, SB202190, and SP600125. These results indicate that S100A8 induces cytokine release via TLR4. Study of PI3K, $PKC{\delta}$, MAPKs, and NF-${\kappa}B$ will contribute to elucidation of the S100A8-invovled mechanism.

• KSBB Journal
• /
• v.4 no.2
• /
• pp.123-127
• /
• 1989

The separation of trypsin inhibitir using reverse micellar system was invertigated. Among the biffer system tested, 1.0M $CaCl_2$ solution (pH 3.0) and 1.0M NaCl soluation (pH 11.5) were most effective for solubilization and de-solubilization of protein, respectively. When these conditions were applied to two model sampeles, one of which was composed of the same amount of 7S protein and trpsin inhibitor, and the other of which was composed of the same amount of soluble soybean protein isolates and trypsin inhibitor, highly pure trypsin inhibitor was obtained. And in the real soybean, Kwng Gyo, pure trypsin inhibior was also obtained.

• Corrosion Science and Technology
• /
• v.10 no.1
• /
• pp.13-23
• /
• 2011

The inhibitive action of thiadiazolopyrimidines on mild steel in 1 M $H_{2}SO_{4}$ has been studied using weight loss, gasometric studies and electrochemical polarization and AC impedance measurements. The effect of temperature on the corrosion behaviour of mild steel in 1 M $H_{2}SO_{4}$ with optimum concentration of inhibitors was studied in the temperature ranging from 313-333K The adsorption of the inhibitor on the surface of mild steel was found to be exothermic, spontaneous and followed the mechanism of physisorption. The adsorption of these compounds on mild steel surface was found to obey Langmuir adsorption isotherm. The protective film formed on the surface of mild steel by the adsorption of inhibitor in 1 M $H_{2}SO_{4}$ solution was confirmed by optical microscopic technique. Synergistic effect of halide ions on mild steel in 1 M $H_{2}SO_{4}$ was studied by weight loss technique.