Pharmaceutical Sciences and Natural Products - Research Publications

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    Cellular uptake, intracellular trafficking and cytotoxicity of silver nanoparticles
    (2012) Singh, R.P.; Ramarao, P.
    Silver nanoparticles (Ag NPs) are used in consumer products and wound dressings due to their antimicrobial properties. However, in addition to toxic effects on microbes, Ag NPs can also induce stress responses as well as cytotoxicity in mammalian cells. We observed that Ag NPs are efficiently internalized via scavenger receptor-mediated phagocytosis in murine macrophages. Confocal and electron microscopy analysis revealed that internalized Ag NPs localize in the cytoplasm. Ag NPs cause mitochondrial damage, induce apoptosis and cell death. These effects were abrogated in presence of Ag ion-reactive, thiol-containing compounds suggesting the central of Ag ions in Ag NP toxicity. Quantitative image analysis revealed that intracellular dissolution of Ag NPs occurs about 50 times faster than in water. In conclusion, we demonstrate for the first time that Ag NPs are internalized by scavenger receptors, trafficked to cytoplasm and induce toxicity by releasing Ag ions. ? 2012 Elsevier Ireland Ltd.
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    Intracellular delivery of redox cycler-doxorubicin to the mitochondria of cancer cell by folate receptor targeted mitocancerotropic liposomes
    (2012) Malhi, Sarandeep Singh; Budhiraja, Abhishek; Arora, Sumit; Chaudhari, Kiran R.; Nepali, Kunal; Kumar, Raj; Sohi, Harmik; Murthy, Rayasa S.R.
    Cancer cells reflect higher level of ROS in comparison to the normal cell, so they become more vulnerable to further oxidative stress induced by exogenous ROS-generating agents. Through this a novel therapeutic strategy has evolved, which involves the delivery of redox cycler-doxorubicin (DOX) to the mitochondria of cancer cell where it acts as a source of exogenous ROS production. The purpose of this study is to develop a liposomal preparation which exhibits a propensity to selectively target cancer cell along with the potential of delivering drug to mitochondria of cell. We have rendered liposomes mitocancerotropic (FA-MTLs) by their surface modification with dual ligands, folic acid (FA) for cancer cell targeting and triphenylphosphonium (TPP) cations for mitochondria targeting. The cytotoxicity, ROS production and cell uptake of doxorubicin loaded liposomes were evaluated in FR (+) KB cells and found to be increased considerably with FA-MTLs in comparison to folic acid appended, mitochondria targeted and non-targeted liposomes. As confirmed by confocal microscopy, the STPP appended liposomes delivered DOX to mitochondria of cancer cell and also showed higher ROS production and cytotoxicity in comparison to folic acid appended and non-targeted liposomes. Most importantly, mitocancerotropic liposomes showed superior activity over mitochondria targeted liposomes which confirm the synergistic effect imparted by the presence of dual ligands - folic acid and TPP on the enhancement of cellular and mitochondrial delivery of doxorubicin in KB cells. ? 2012 Elsevier B.V. All rights reserved.
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    Radiation resistance: Cancer stem cells (CSCs) and their enigmatic pro-survival signaling
    (Academic Press, 2015) Skvortsov, Ira; Debbage, Paul; Kumar, Vinod; Skvortsov, Sergej
    Despite the fact that radiation therapy is a highly effective therapeutic approach, a small intratumoral cell subpopulation known as "cancer stem cells" (CSCs) is radiation-resistant and possesses specific molecular properties protecting it against radiation-induced damage. The exact mechanisms of this radioresistance are still not fully elucidated, but they relate to these cells' enhanced DNA repair capacities and their low intracellular ROS concentrations, resulting from their up-regulation of ROS scavengers. The low ROS content is accompanied by disturbances in cell cycle regulation, so it can be assumed that either CSCs are quiescent or dormant themselves, or that this cell population consists of at least two cell subpopulations: the normally and the slowly proliferating cells (quiescent or dormant cells). Slowly dividing CSCs show concomitant dysregulation of the signaling molecules mediating both cell cycle progression and maintenance of cell stemness. Despite a massive accumulation of data concerning the mechanisms underlying DNA damage response in CSCs, it represents a challenge to researchers in the era of personalized medicine to elucidate the role of intracellular ROS and of signaling pathways associated with the radiation resistance of these cells; there is a clear need to understand the molecular mechanisms helping CSCs to survive radiation exposure. � 2015 Elsevier Ltd.