Magneto-transport Properties in SrRu<SUB>0.7</SUB>Fe<SUB>0.3</SUB>O<SUB>3-δ</SUB> Epitaxial Thin Film

Umasankar Dash,Chang-Uk Jung 한국자기학회 2018 Journal of Magnetics Vol.23 No.3

We investigated the magnetotransport properties in SrRu0.7Fe0.3O3-δ epitaxial thin film synthesized by using pulsed laser deposition. X-ray diffraction (XRD) θ − 2θ and reciprocal space mapping scans showed strong peaks demonstrating high quality. The image of step and terrace at atomic force microscope scan image of the film showed a layer by layer growth mode of the thin film. The resistivity showed a significant decrease by applying magnetic field of 9 T, which could be described in terms of spin dependent scattering. The zero-field resistivity at low temperature (2 K-24 K) was fitted very well with a variable range hopping model. The observed negative magnetoresistance (T = 10 K, H = 9 T) was as high as ~20%.

Structural, magnetic and transport behavior of SrRu<SUB>0.7</SUB>Fe<SUB>0.3</SUB>O₃ epitaxial thin film

Umasankar Dash,Chang Uk Jung 한국자기학회 2017 한국자기학회 학술연구발표회 논문개요집 Vol.2017 No.5

A New Histone Deacetylase Inhibitor, MHY219, Inhibits the Migration of Human Prostate Cancer Cells via HDAC1

( Umasankar De ),( Soma Kundu ),( Nabanita Patra ),( Mee Young Ahn ),( Ji Hae Ahn ),( Ji Yeon Son ),( Jung Hyun Yoon ),( Hyung Ryoung Moon ),( Byung Mu Lee ),( Hyung Sik Kim ) 한국응용약물학회 2015 Biomolecules & Therapeutics(구 응용약물학회지) Vol.23 No.5

Histone deacetylase (HDAC) inhibitors are considered novel agents for cancer chemotherapy. We previously investigated MHY219, a new HDAC inhibitor, and its potent anticancer activity in human prostate cancer cells. In the present study, we evaluated MHY219 molecular mechanisms involved in the regulation of prostate cancer cell migration. Similar to suberanilohydroxamic acid (SAHA), MHY219 inhibited HDAC1 enzyme activity in a dose-dependent manner. MHY219 cytotoxicity was higher in LNCaP (IC50=0.67 μM) than in DU145 cells (IC50=1.10 μM) and PC3 cells (IC50=5.60 μM) after 48 h of treatment. MHY219 significantly inhibited the HDAC1 protein levels in LNCaP and DU145 cells at high concentrations. However, inhibitory effects of MHY219 on HDAC proteins levels varied based on the cell type. MHY219 significantly inhibited LNCaP and DU145 cells migration by downregulation of matrix metalloprotease-1 (MMP-1) and MMP-2 and induction of tissue inhibitor of metalloproteinases-1 (TIMP-1). These results suggest that MHY219 may potentially be used as an anticancer agent to block cancer cell migration through the repression of MMP-1 and MMP-2, which is related to the reduction of HDAC1.

Detwinning Monoclinic Phase BiMnO₃ Thin Film

Umasankar Dash,N. V. Raveendra,Chang Uk Jung 한국자기학회 2016 Journal of Magnetics Vol.21 No.2

BiMnO₃ has been a promising candidate as a magnetoelectric multiferroic while there have been many controversial reports on its ferroelectricity. The detailed analysis of its film growth, especially the growth of thin film having monoclinic symmetry has not been reported. We studied the effect of miscut angle, the substrate surface, and film thickness on the symmetry of BiMnO₃ thin film. A flat SrTiO₃ (110) substrate resulted in a thin film with three domains of BiMnO₃ and 1 degree miscut in the SrTiO₃ (110) substrate resulted in dominant domain preference in the BiMnO₃ thin film. The larger miscut resulted in a nearly perfect detwinned BiMnO₃ film with a monoclinic phase. This strong power of domain selection due to the step edge of the substrate was efficient even for the thicker film which showed a rather relaxed growth behavior along the SrTiO₃ [1-10] direction.

A New Histone Deacetylase Inhibitor, MHY219, Inhibits the Migration of Human Prostate Cancer Cells via HDAC1

De, Umasankar,Kundu, Soma,Patra, Nabanita,Ahn, Mee Young,Ahn, Ji Hae,Son, Ji Yeon,Yoon, Jung Hyun,Moon, Hyung Ryoung,Lee, Byung Mu,Kim, Hyung Sik The Korean Society of Applied Pharmacology 2015 Biomolecules & Therapeutics(구 응용약물학회지) Vol.23 No.5

Histone deacetylase (HDAC) inhibitors are considered novel agents for cancer chemotherapy. We previously investigated MHY219, a new HDAC inhibitor, and its potent anticancer activity in human prostate cancer cells. In the present study, we evaluated MHY219 molecular mechanisms involved in the regulation of prostate cancer cell migration. Similar to suberanilohydroxamic acid (SAHA), MHY219 inhibited HDAC1 enzyme activity in a dose-dependent manner. MHY219 cytotoxicity was higher in LNCaP ($IC_{50}=0.67{\mu}M$) than in DU145 cells ($IC_{50}=1.10{\mu}M$) and PC3 cells ($IC_{50}=5.60{\mu}M$) after 48 h of treatment. MHY219 significantly inhibited the HDAC1 protein levels in LNCaP and DU145 cells at high concentrations. However, inhibitory effects of MHY219 on HDAC proteins levels varied based on the cell type. MHY219 significantly inhibited LNCaP and DU145 cells migration by down-regulation of matrix metalloprotease-1 (MMP-1) and MMP-2 and induction of tissue inhibitor of metalloproteinases-1 (TIMP-1). These results suggest that MHY219 may potentially be used as an anticancer agent to block cancer cell migration through the repression of MMP-1 and MMP-2, which is related to the reduction of HDAC1.

Magnetoresistance Versus Oxygen Deficiency in Epi-stabilized SrRu _{1 − <i>x</i>} Fe _<i>x</i> O _{3 − <i>δ</i>} Thin Films

Dash, Umasankar,Acharya, Susant Kumar,Lee, Bo Wha,Jung, Chang Uk Springer US 2017 Nanoscale research letters Vol.12 No.1

<P>Oxygen vacancies have a profound effect on the magnetic, electronic, and transport properties of transition metal oxide materials. Here, we studied the influence of oxygen vacancies on the magnetoresistance (MR) properties of SrRu<SUB>1 − <I>x</I></SUB>Fe<SUB><I>x</I></SUB>O<SUB>3 - <I>δ</I></SUB> epitaxial thin films (<I>x</I> = 0.10, 0.20, and 0.30). For this purpose, we synthesized highly strained epitaxial SrRu<SUB>1 − <I>x</I></SUB>Fe<SUB><I>x</I></SUB>O<SUB>3 − <I>δ</I></SUB> thin films with atomically flat surfaces containing different amounts of oxygen vacancies using pulsed laser deposition. Without an applied magnetic field, the films with <I>x</I> = 0.10 and 0.20 showed a metal–insulator transition, while the <I>x</I> = 0.30 thin film showed insulating behavior over the entire temperature range of 2–300 K. Both Fe doping and the concentration of oxygen vacancies had large effects on the negative MR contributions. For the low Fe doping case of <I>x</I> = 0.10, in which both films exhibited metallic behavior, MR was more prominent in the film with fewer oxygen vacancies or equivalently a more metallic film. For semiconducting films, higher MR was observed for more semiconducting films having more oxygen vacancies. A relatively large negative MR (~36.4%) was observed for the <I>x</I> = 0.30 thin film with a high concentration of oxygen vacancies (<I>δ</I> = 0.12). The obtained results were compared with MR studies for a polycrystal of (Sr<SUB>1 − <I>x</I></SUB>La<SUB><I>x</I></SUB>)(Ru<SUB>1 − <I>x</I></SUB>Fe<SUB><I>x</I></SUB>)O<SUB>3</SUB>. These results highlight the crucial role of oxygen stoichiometry in determining the magneto-transport properties in SrRu<SUB>1 − <I>x</I></SUB>Fe<SUB><I>x</I></SUB>O<SUB>3 − <I>δ</I></SUB> thin films.</P>

The dynamics of glassy behavior in SrRu1-Fe O3 heterostructure

Dash Umasankar,Pradhan Soumen,Rao M.S. Ramachandra,Veillon F.,Prellier W.,Jung Chang Uk 한국물리학회 2024 Current Applied Physics Vol.58 No.-

We report the magnetic interactions in SrRu1-xFexO3 epitaxial thin films. All the films showed a single-phase and good step-terrace structure with minimal surface roughness. The X-ray photoelectron spectra of Fe and Ru revealed that both transition metal elements exist in the films as Fe3+ and Ru4+. With Fe doping, the itinerant ferromagnetic behavior and ferromagnetic transition temperature gradually decreased, but the coercivity field increased. The magnetic interplay between Fe3+-O-Fe3+ is coined as antiferromagnetic. There was another interaction between Ru4+-O-Fe3+ which is best described as ferromagnetic. Furthermore, the magnetic frustration in our films caused by the doped Fe resulted in dynamic glassy behavior. On the other hand, the epitaxial strain from the imminent SrTiO3 substrate along with change in oxygen vacancy might have strong evidence for the spin-glass nature in our thin films.

A New Synthetic Histone Deacetylase Inhibitor, MHY2256, Induces Apoptosis and Autophagy Cell Death in Endometrial Cancer Cells via p53 Acetylation

De, Umasankar,Son, Ji Yeon,Sachan, Richa,Park, Yu Jin,Kang, Dongwan,Yoon, Kyungsil,Lee, Byung Mu,Kim, In Su,Moon, Hyung Ryong,Kim, Hyung Sik MDPI 2018 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.19 No.9

<P>We previously discovered a novel sirtuin (SIRT) inhibitor, MHY2256, that exerts anticancer activity through p53 acetylation in MCF-7 human breast cancer cells. We investigated the anticancer activity of MHY2256 against hormone-related cancer, an endometrial cancer with a poor prognosis. The IC<SUB>50</SUB> values of MHY2256 were shown to be much lower than those of salermide, a well-known SIRT inhibitor. Furthermore, MHY2256 significantly reduced the protein expression and activities of SIRT1, 2, and 3, with similar effects to salermide. Particularly, MHY2256 markedly inhibited tumor growth in a tumor xenograft mouse model of Ishikawa cancer cells. During the experimental period, there was no significant change in the body weight of mice treated with MHY2256. A detailed analysis of the sensitization mechanisms of Ishikawa cells revealed that late apoptosis was largely increased by MHY2256. Additionally, MHY2256 increased G1 arrest and reduced the number of cell cyclic-related proteins, suggesting that apoptosis by MHY2256 was achieved by cellular arrest. Particularly, p21 was greatly increased by MHY225656, suggesting that cell cycle arrest by p21 is a major factor in MHY2256 sensitization in Ishikawa cells. We also detected a significant increase in acetylated p53, a target protein of SIRT1, in Ishikawa cells after MHY2256 treatment. In a mouse xenograft model, MHY2256 significantly reduced tumor growth and weight without apparent side effects. These results suggest that MHY2256 exerts its anticancer activity through p53 acetylation in endometrial cancer and can be used for targeting hormone-related cancers.</P>

Plumbagin from a tropical pitcher plant (<i>Nepenthes alata</i> Blanco) induces apoptotic cell death via a p53-dependent pathway in MCF-7 human breast cancer cells

De, Umasankar,Son, Ji Yeon,Jeon, Yukyoung,Ha, Song-Yi,Park, Yu Jin,Yoon, Sungpil,Ha, Ki-Tae,Choi, Wahn Soo,Lee, Byung Mu,Kim, In Su,Kwak, Jong Hwan,Kim, Hyung Sik Elsevier 2019 Food and chemical toxicology Vol.123 No.-

<P><B>Abstract</B></P> <P>Plumbagin (5-hydroxy-2-methyl-1,4-naphthaquinone) has displayed antitumor activity <I>in vitro</I> and in animal models; however, the underlying molecular mechanisms have not been fully explored. The aim of this study was to investigate the anticancer effects of plumbagin isolated from <I>Nepenthes alata</I> against MCF-7 breast cancer cells. We examined the cytotoxicity, cell cycle regulation, apoptotic cell death, and generation of intracellular reactive oxygen species (ROS) in MCF-7 cells. Plumbagin exhibited potent cytotoxicity in MCF-7 cells (wild-type p53) compared to that in SK-OV-3 (null-type) human epithelial ovarian cancer cells. Specifically, plumbagin upregulated the expression of p21<SUP>CIP1/WAF1</SUP> in MCF-7 cells, causing cell cycle arrest in the G2/M phase through inhibition of cyclin B1 levels. Plumbagin also significantly increased the ratio of Bax/Bcl-2 and release of cytochrome c, resulting in apoptotic cell death in MCF-7 cells. Furthermore, plumbagin dramatically increased the intracellular ROS level, whereas pretreatment with the ROS scavenger N-acetyl cysteine protected against plumbagin-induced cytotoxicity, suggesting that ROS formation plays a pivotal role in antitumor activity in MCF-7 cells. In mice bearing MCF-7 cell xenografts, plumbagin significantly reduced tumor growth and weight without apparent side effects. We therefore concluded that plumbagin exerts anticancer activity against MCF-7 cells through the generation of intracellular ROS, resulting in the induction of apoptosis via a p53-dependent pathway. This study thus identifies a new anticancer mechanism of plumbagin against p53-dependent breast cancer cells and suggests a novel strategy for overcoming of breast cancer therapy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Plumbagin, first isolated from <I>N. alata</I>, exhibits anticancer activity in human breast cancer MCF-7 cells. </LI> <LI> ROS generation contributes to the cytotoxicity of plumbagin against MCF7 cells. </LI> <LI> Plumbagin act as a lead molecule for new anticancer drug against breast cancer patients. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Large magnetoresistance in LaFeO₃-substituted SrRuO₃ epitaxial thin films

Dash, Umasankar,Acharya, Susant Kumar,Cho, Seong Won,Lee, Suyoun,Lee, Kyoungjun,Chae, Seung Chul,Cho, Myung Rae,Jung, Chang Uk Elsevier 2017 Journal of alloys and compounds Vol.724 No.-

<P><B>Abstract</B></P> <P>In this work, the magnetotransport properties of epitaxial Sr<SUB>1-<I>x</I> </SUB>La<SUB> <I>x</I> </SUB>Ru<SUB>1-<I>x</I> </SUB>Fe<SUB> <I>x</I> </SUB>O<SUB>3</SUB> (<I>x</I> = 0.05, 0.10, 0.20, and 0.30) thin films grown by pulsed laser deposition on SrTiO<SUB>3</SUB> (001) substrates were investigated. Compared to doping Fe into the Ru<SUP>4+</SUP> site of SrRuO<SUB>3</SUB>, doping LaFeO<SUB>3</SUB> into SrRuO<SUB>3</SUB> resulted in an increase in the zero-field resistivity. A larger zero-field resistivity value in magnetic perovskite oxide is, in many cases, favorable for obtaining high magnetoresistance. The films (0.0 ≤ <I>x</I> ≤ 0.10) showed metallic behavior and ferromagnetic ordering, although the resistivity increased and the ferromagnetic transition temperature <I>T</I> <SUB>C</SUB> decreased with an increase in <I>x</I>. The thin film with <I>x</I> = 0.20 displayed a clear metal-to-insulator phase transition at low temperature and also displayed a well-defined resistivity minimum. This upturn in the resistivity curve is associated with the large electron-electron interaction present in the material. The magnetoresistance values increased as <I>x</I> increased, and we observed a large negative magnetoresistance (MR = −35%) for the thin film with <I>x</I> = 0.30. The observed high MR values are associated with spin fluctuation of the mobile electronic carriers in the material.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sr<SUB>1-<I>x</I> </SUB>La<SUB> <I>x</I> </SUB>Ru<SUB>1-<I>x</I> </SUB>Fe<SUB> <I>x</I> </SUB>O<SUB>3</SUB> epitaxial thin films were grown by PLD. </LI> <LI> The structural and magnet-transport properties of thin films were investigated. </LI> <LI> Metal-insulator transition was found in Sr<SUB>0.8</SUB>La<SUB>0.2</SUB>Ru<SUB>0.8</SUB>Fe<SUB>0.2</SUB>O<SUB>3</SUB> thin film. </LI> <LI> The upturn of <I>ρ</I> of Sr<SUB>0.8</SUB>La<SUB>0.2</SUB>Ru<SUB>0.8</SUB>Fe<SUB>0.2</SUB>O<SUB>3</SUB> film was explained by e-e interactions. </LI> <LI> Magnetoresistance up to ∼35% were found for Sr<SUB>0.7</SUB>La<SUB>0.3</SUB>Ru<SUB>0.7</SUB>Fe<SUB>0.3</SUB>O<SUB>3</SUB> film. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>