Co-treatment of LY294002 or MK-2206 with AZD5363 Attenuates AZD5363-induced Increase in the Level of Phosphorylated AKT

CHOI, AE-RAN,KIM, JU-HWA,WOO, YEON HWA,CHEON, JI HYUN,KIM, HYUNG SIK,YOON, SUNGPIL Potamitis Press 2016 Anticancer research Vol.36 No.11

<P>Clinical trials are in progress on AZD5363, an inhibitor of protein kinase B (AKT), to assess its effects on the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway. Cells treated with AKT inhibitors have been reported to activate alternative pathways in order to escape growth inhibition. AZD5363-sensitized Hs578T breast cancer cells displayed reduced levels of phosphorylated glycogen synthase kinase 3 beta (pGSK3 beta). Interestingly, in AZD5363-treated cells, the level of phosphorylated (activated) AKT (pAKT) increased. Since pAKT positively correlates with cancer growth and survival, we aimed to identify conditions that could reduce AZD5363-induction of pAKT. We examined whether AZD5363 induction of pAKT could be reduced by co-treatment with inhibitors of the PI3K/AKT/mTOR pathway (LY294002, MK-2206, wortmannin, perifosine, rapamycin, everolimus, and temsirolimus). We observed that co-treatment of LY294002 or MK-2206 with AZD5363 reduced the level of pAKT. Since MK-2206 is clinically used, we propose that co-treatment using MK-2206 with AZD5363 would prove beneficial in blocking the AZD5363-induced pAKT signaling pathway. Our findings contribute to the development of AZD5363-based sensitization therapies for patients with cancer.</P>

Characterization of a Septobasidium sp. Associated with Felt Disease of Schisandra chinensis

Choi, In-Young,Lee, Wang-Hyu,Lee, Jong-Jin,Park, Mi-Jeong,Ko, Jeong-Ae,Choi, Jeong-Ran,Shin, Hyeon-Dong The Korean Society of Mycology 2016 Mycobiology Vol.44 No.1

Extensive disease surveys performed during the summers of 2013 and 2014 in Schisandra chinensis orchards resulted in the finding of a Septobasidium sp. associated with felt disease. The fungus was characterized to be symbiotic with a scale insect (Pseudaulacaspis cockerelli). Morphological and molecular characteristics of the Septobasidium isolates were investigated. The isolates were morphologically and phylogenetically close to S. bogoriense. We tentatively describe this isolate as a Septobasidium sp., mainly because of the limited amount of information available on the internal transcribed spacer region of the ribosomal DNA of Septobasidium spp.

Sensitization of Cancer Cells through Reduction of Total Akt and Downregulation of Salinomycin-Induced pAkt, pGSk3 <i>β</i> , pTSC2, and p4EBP1 by Cotreatment with MK-2206

Choi, Ae-Ran,Kim, Ju-Hwa,Yoon, Sungpil Hindawi Publishing Corporation 2014 BioMed research international Vol.2014 No.-

<P>MK-2206 is an inhibitor of Akt activation. It has been investigated as an anticancer drug in clinical trials assessing the potential of pAkt targeting therapy. The purpose of this study was to identify conditions that increase the sensitivity of cancer cells to MK-2206. We found that the treatment of cancer cells with a high concentration of salinomycin (Sal) reduced total Akt protein levels but increased activated Akt levels. When cancer cells were cotreated with MK-2206 and Sal, both pAkt and total Akt levels were reduced. Using microscopic observation, an assessment of cleaved PARP, FACS analysis of pre-G1 region, and Hoechst staining, we found that Sal increased apoptosis of MK-2206-treated cancer cells. These results suggest that cotreatment with MK-2206 and Sal sensitizes cancer cells via reduction of both pAkt and total Akt. Furthermore, cotreatment of cancer cells with Sal and MK-2206 reduced pp70S6K, pmTOR, and pPDK1 levels. In addition, Sal-induced activation of GSK3<I>β</I>, TSC2, and 4EBP1 was abolished by MK-2206 cotreatment. These results suggest that cotreatment using MK-2206 and Sal could be used as a therapeutic method to sensitize cancer cells through targeting of the PI3K/Akt/mTOR pathway. Our findings may contribute to the development of MK-2206-based sensitization therapies for cancer patients.</P>

Dimethyl sulfoxide reduction by a hyperhermophilic archaeon Thermococcus onnurineus NA1 via a cysteine-cystine redox shuttle

Ae Ran Choi,Min-Sik Kim,Sung Gyun Kang,Hyun Sook Lee 한국미생물학회 2016 The journal of microbiology Vol.54 No.1

A variety of microbes grow by respiration with dimethyl sulfoxide (DMSO) as an electron acceptor, and several distinct DMSO respiratory systems, consisting of electron carriers and a terminal DMSO reductase, have been characterized. The heterotrophic growth of a hyperthermophilic archaeon Thermococcus onnurineus NA1 was enhanced by the addition of DMSO, but the archaeon was not capable of reducing DMSO to DMS directly using a DMSO reductase. Instead, the archaeon reduced DMSO via a cysteine-cystine redox shuttle through a mechanism whereby cystine is microbially reduced to cysteine, which is then reoxidized by DMSO reduction. A thioredoxin reductase-protein disulfide oxidoreductase redox couple was identified to have intracellular cystine-reducing activity, permitting recycle of cysteine. This study presents the first example of DMSO reduction via an electron shuttle. Several Thermococcales species also exhibited enhanced growth coupled with DMSO reduction, probably by disposing of excess reducing power rather than conserving energy.

[ $^1H$ ] Nuclear Magnetic Resonance Study of Ferroelectric $(NH_4)_3H(SO_4)_2$

Choi, S.H.,Han, K.S.,Kwon, S.K.,Nam, S.K.,Choi, H.H.,Lee, Moo-Hee,Lim, Ae-Ran Korean Magnetic Resonance Society 2007 Journal of the Korean Magnetic Resonance Society Vol.11 No.2

[ $^1H$ ] nuclear magnetic resonance (NMR) experiments have been performed at 30 - 300 K and 7 T to investigate dynamics of hydrogen bond network in the single crystal $(NH_4)_3H(SO_4)_2$. The two proton sites, ammonium proton and hydrogen-bond proton, are identified from the $^1H$ NMR MAS spectrum at 340 K. As temperature decreases, the $^1H$ NMR spectrum shifts to the higher frequency side with a larger linewidth. The spectrum at 65 K shows a distinctive change in line shape toward the ferroelectric transition at 63 K. The measured values of $T_1$ for ammonium and hydrogen-bond protons are similar in the whole range of temperature. $T_1$ of $^1H$ NMR shows a gradual decrease down to 120 K and starts to steeply increase below 100 K. Then $T_1$ shows abrupt decrease below 70 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. This temperature dependence of spectrum and $T_1$ clearly prove that the large change in the dynamics of hydrogen bond network is associated with the ferroelectric phase transition at 63 K.

Attenuation of Colchicine Toxicity in Drug-resistant Cancer Cells by Co-treatment with Anti-malarial Drugs

CHOI, AE-RAN,KIM, JU-HWA,CHEON, JI HYUN,KIM, HYUNG SIK,YOON, SUNGPIL Potamitis Press 2016 Anticancer research Vol.36 No.11

<P>Background/Aim: Colchicine (COL) is a wellknown and potent microtubule targeting anticancer agent. The purpose of our study was to identify conditions that increase sensitization of COL-resistant cancer cells that overexpress P-glycoprotein (P-gp). Materials and Methods: The anti-malarial drugs chloroquine (CHL), mefloquine (MEF) and primaquine (PRI) have been shown to increase sensitization in drug-resistant KBV20C cells via P-gp inhibition. Therefore, we tested whether co-treatment of COL with PRI, CHL or MEF increases sensitivity in COL-resistant KBV20C cells over that of cells treated with COL alone and whether these effects are attributable to P-gp activity. Results: Interestingly, we found that both CHL and PRI, but not MEF, reduced cytotoxicity in KBV20C cells receiving high concentrations of COL, suggesting that the effects of CHL and PRI have specific mechanisms among the anti-malarial drugs. The effects of CHL and PRI were specific to COL-resistant cells, since we did not detect a reduction in cytotoxicity in drug-sensitive parent KB cells. These data suggest that CHL and PRI inhibit the signaling pathways of COL-treated-resistant cells without P-gp inhibition. Furthermore, we studied the molecular mechanisms underlying the effects of COL-CHL co-treatment in KBV20C cells. FACS analysis, annexin V staining and western blot analysis revealed that G(2) arrest and apoptosis were lower in cells co-treated with COL and CHL than in cells treated with COL alone. We also found that pH2AX, pHistone H3 and pRb expression was highly reduced in COL-CHL co-treated cells but not in COL-VIB co-treated cells. In addition, expression of the p21 protein, which correlates with drug-resistant phenotypes, increased in cells receiving COL-CHL co-treatment over that of COL-treated cells. Conclusion: These results suggest that reduced G(2) arrest and apoptosis resulting from COL-CHL co-treatment was attributable to DNA damage and reduced cell cycle progression. These findings provide important information regarding the prevention of COL toxicity in COL-resistant cells and indicate that CHL, PRI and MEF may contribute to sensitization in COL-resistant cells.</P>

Identification and Cloning of the ClpB Gene in Psychromonas arctica by Inverse PCR and Cassette PCR Technology

Choi, Ae-Ran,Na, Joo-Mi,Sung, Min-Sun,Im, Ha-Na,Lee, Kyung-Hee Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.4

The family of ClpB protein is a molecular chaperone which protects cellular proteins from being aggregated upon exposure to severe environmental stresses in association with DnaK/DanJ/GrpE in the ATP-dependent manner. In a psychrophilic bacterium which survives at a subzero temperature, any functional role of cold-active ClpB protein can be rather crucial. In order to identify a ClpB encoding gene from a cold-adapted bacterium whose genome sequence has not been fully discovered, we have employed a series of PCR technologies, including a gradient PCR with homologous primers, an inverse PCR and a cassette PCR. The full sequence of PaclpB gene was successfully identified and compared with those of other psychrophilic species. We have further cloned the gene in E.coli expression systems and were able to induce PaClpB protein expression by IPTG, which help us understand a molecular mechanism for survival against extremely cold environments.

Nucleus-phonon interactions of MCsSO₄ (M = Na, K, or Rb) single crystals studied using spin-lattice relaxation time

Choi, Jae Hun,Kim, Nam Hee,Lim, Ae Ran Korean Magnetic Resonance Society 2014 Journal of the Korean Magnetic Resonance Society Vol.18 No.1

The structural properties and relaxation processes of $MCsSO_4$ (M = Na, K, or Rb) crystals were investigated by measuring the NMR spectra and spin-lattice relaxation rates $1/T_1$ of their $^{23}Na$, $^{39}K$, $^{87}Rb$, and $^{133}Cs$ nuclei. According to the NMR spectra, the $MCsSO_4$ crystals contain two crystallographically inequivalent sites each for the M and Cs ions. Further, the relaxation rates of all these nuclei do not change significantly over the investigated temperature range, indicating that no phase transitions occur in these crystals in this range. The variations in the $1/T_1$ values of the $^{23}Na$, $^{39}K$, $^{87}Rb$, and $^{133}Cs$ nuclei in these three crystals with increasing temperature are approximately proportional to $T^2$, indicating that Raman processes may be responsible for the relaxation. Therefore, for nuclear quadrupole relaxation of the $^{23}Na$, $^{39}K$, $^{87}Rb$, and $^{133}Cs$ nuclei, Raman processes with n = 2 are more effective than direct processes.

Preclinical Biosafety Evaluation of Genetically Modified Human Adipose Tissue-Derived Mesenchymal Stem Cells for Clinical Applications to Brainstem Glioma

Choi, Seung Ah,Yun, Jun-Won,Joo, Kyeung Min,Lee, Ji Yeoun,Kwak, Pil Ae,Lee, Young Eun,You, Ji-Ran,Kwon, Euna,Kim, Woo Ho,Wang, Kyu-Chang,Phi, Ji Hoon,Kang, Byeong-Cheol,Kim, Seung-Ki Mary Ann Liebert 2016 STEM CELLS AND DEVELOPMENT Vol.25 No.12

洛東江 下流城 濫藻 Anabaena의 個體群 變動 및 毒性 硏究

Choi, Ae-Ran,Park, Jin-Hong,Lee, Jin-Ae 한국조류학회(藻類) 2002 ALGAE Vol.17 No.2

Population dynamics of Anabaena and the anatoxin-a concentration were monitored with physicochemical parameters at 3 sites in the lower Naktong River from May to September in 2000. Total 4 species of Anabaena (A. flosaquae, A. smithii, A. ucrainica and A. mucosa) were identified with morphological characterisitcs. Anabaena flos-aquae was most abundant among the populations. The standing crop of Anabaena ranged from 10 to 11,220 cells · $ml^{-1}$ and biomass of Anabaena more 1,000 cells · $ml^{-1}$ was obseved once at St. Mulgeum and St. Seonam, twice at St. Hagueon out of total 9 samplings. There were not significant correlations between the standing crop of Anabaena and other physicochemical parameters such as temperature, nitrate, total nitrogen, phosphate, total phophorus and N/P ratios. The frequency of trichomes with akinetes was low and ranged from 0 to 4% in the total Anabaena population and A. smithii showed highest frequency of 2.8% among all species. The population at St. Seonam showed highest frequency of 1.4% among all sampling sties. The population in September showed the highest frequency of 3.0% among all sampling period. The frequency of trichomes with heterocysts was low and ranged from 1 to 87% inthe total Anabaena population and A. smithii showed highest frequency of 55.1% among all species. The population at St. Mulgeum showed highest frequency of 17.6% among all sampling sites. The population in August showed the highest frequency of 21.4% among all sampling period. The frequency of trichomes with akinetes and/or heterocysts was not related to all the physicochemical parameters of temperature, nitrate, total nitrogen, phosphate, total phosphorus and N/P ratios. The anatoxin-a concentations were determined in algal materials dominated by Microcystis and Anabaena from June though August by derivatization using 7-fluoro-4-nitro-2, 1,3-benzoxadiazole (NBD-F) and HPLC analysis with fluorimetric detection. All the concentrations were below the detection limit of 0.1 ㎍ · $l^{-1}$ in the present study.