Publications by authors named "Sankar Mohan"

Prostate cancer (PCa) patients undergoing androgen deprivation therapy almost invariably develop castration-resistant prostate cancer (CRPC). Targeting the androgen receptor (AR) Binding Function-3 (BF3) site offers a promising option to treat CRPC. However, BF3 inhibitors have been limited by poor potency or inadequate metabolic stability.

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Arsenic-free drinking water, independent of electrical power and piped water supply, is possible only through advanced and affordable materials with large uptake capacities. Confined metastable 2-line ferrihydrite, stable at ambient temperature, shows continuous arsenic uptake in the presence of other complex species in natural drinking water and an affordable water-purification device is made using the same.

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Unlabelled: Influenza virus neuraminidase (NA) drug resistance is one of the challenges to preparedness against epidemic and pandemic influenza virus infections. NA N1- and N2-containing influenza viruses are the primary cause of seasonal epidemics and past pandemics. The structural and functional basis underlying drug resistance of the influenza virus N1 NA is well characterized.

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UDP-galactopyranose mutase (UGM), a key enzyme in the biosynthesis of mycobacterial cell walls, is a potential target for the treatment of tuberculosis. In this work, we investigate binding models of a non-substrate-like inhibitor, MS-208, with M. tuberculosis UGM.

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The primary sweet sensor in mammalian taste cells for sugars and noncaloric sweeteners is the heteromeric combination of type 1 taste receptors 2 and 3 (T1R2+T1R3, encoded by Tas1r2 and Tas1r3 genes). However, in the absence of T1R2+T1R3 (e.g.

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Uridine diphosphate-galactopyranose mutase (UGM), an enzyme found in many eukaryotic and prokaryotic human pathogens, catalyzes the interconversion of UDP-galactopyranose (UDP-Galp) and UDP-galactofuranose (UDP-Galf), the latter being used as the biosynthetic precursor of the galactofuranose polymer portion of the mycobacterium cell wall. We report here the synthesis of a sulfonium and selenonium ion with an appended polyhydroxylated side chain. These compounds were designed as transition state mimics of the UGM-catalyzed reaction, where the head groups carrying a permanent positive charge were designed to mimic both the shape and positive charge of the proposed galactopyranosyl cation-like transition state.

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Background: PTEN gene loss occurs frequently in castration-resistant prostate cancer (CRPC) and may drive progression through activation of the PI3K/AKT pathway. Here, we developed a novel CTC-based assay to determine PTEN status and examined the correlation between PTEN status in CTCs and matched tumour tissue samples.

Methods: PTEN gene status in CTCs was evaluated on an enrichment-free platform (Epic Sciences) by fluorescence in situ hybridisation (FISH).

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Purpose: In a recent phase II study of onartuzumab (MetMAb), patients whose non-small cell lung cancer (NSCLC) tissue scored as positive for MET protein by immunohistochemistry (IHC) experienced a significant benefit with onartuzumab plus erlotinib (O+E) versus erlotinib. We describe development and validation of a standardized MET IHC assay and, retrospectively, evaluate multiple biomarkers as predictors of patient benefit.

Experimental Design: Biomarkers related to MET and/or EGF receptor (EGFR) signaling were measured by IHC, FISH, quantitative reverse transcription PCR, mutation detection techniques, and ELISA.

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We have previously reported a potent neuraminidase inhibitor that comprises a carbocyclic analogue of zanamivir in which the hydrophilic glycerol side chain is replaced by the hydrophobic 3-pentyloxy group of oseltamivir. This hybrid inhibitor showed excellent inhibitory properties in the neuraminidase inhibition assay (Ki =0.46 nM; Ki (zanamivir) =0.

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Activation of Checkpoint kinase 1 (Chk1) following DNA damage mediates cell cycle arrest to prevent cells with damaged DNA from entering mitosis. Here we provide a high-resolution analysis of cells as they undergo S- and G₂-checkpoint bypass in response to Chk1 inhibition with the selective Chk1 inhibitor GNE-783. Within 4-8 h of Chk1 inhibition following gemcitabine induced DNA damage, cells with both sub-4N and 4N DNA content prematurely enter mitosis.

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The influenza virus neuraminidase (NA) is essential for the virus life cycle. The rise of resistance mutations against current antiviral therapies has increased the need for the development of novel inhibitors. Recent efforts have targeted a cavity adjacent to the catalytic site (the 150-cavity) in addition to the primary catalytic subsite in order to increase specificity and reduce the likelihood of resistance.

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In humans, four different enzymes mediate the digestion of ingested carbohydrates. First salivary and pancreatic α-amylases, the two endoacting retaining glucosidases, break down the complex starch molecules into smaller linear maltose-oligomers (LM) and branched α-limit dextrins (αLDx). Then two retaining exoglucosidases, maltase-glucoamylase (MGAM) and sucrase-isomaltase (SI), convert those molecules into glucose in the small intestine.

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Creation of affordable materials for constant release of silver ions in water is one of the most promising ways to provide microbially safe drinking water for all. Combining the capacity of diverse nanocomposites to scavenge toxic species such as arsenic, lead, and other contaminants along with the above capability can result in affordable, all-inclusive drinking water purifiers that can function without electricity. The critical problem in achieving this is the synthesis of stable materials that can release silver ions continuously in the presence of complex species usually present in drinking water that deposit and cause scaling on nanomaterial surfaces.

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Purpose: Class 1 phosphatidylinositol 3-kinase (PI3K) plays a major role in cell proliferation and survival in a wide variety of human cancers. Here, we investigated biomarker strategies for PI3K pathway inhibitors in non-small-cell lung cancer (NSCLC).

Experimental Design: Molecular profiling for candidate PI3K predictive biomarkers was conducted on a collection of NSCLC tumor samples.

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Enzymes involved in N-glycan processing are targets of interest in the inhibition of host processes for the blockade of dengue virus (DENV) morphogenesis. Of the ten proteins encoded by DENV, three have N-glycosylation sites, namely pre-membrane/membrane protein (prM/M), envelope protein (E) and non-structural protein-1 (NS1). It is known that aberrations in the oligosaccharide portions at these N-glycan sites affect proper folding of these proteins during the translation process that, in turn, affects the morphogenesis of the budding DENV.

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Purpose: Mutation in isocitrate dehydrogenase 1 (IDH1) at R132 (IDH1(R132MUT)) is frequent in low-grade diffuse gliomas and, within glioblastoma (GBM), has been proposed as a marker for GBMs that arise by transformation from lower-grade gliomas, regardless of clinical history. To determine how GBMs arising with IDH1(R132MUT) differ from other GBMs, we undertook a comprehensive comparison of patients presenting clinically with primary GBM as a function of IDH1(R132) mutation status.

Patients And Methods: In all, 618 treatment-naive primary GBMs and 235 lower-grade diffuse gliomas were sequenced for IDH1(R132) and analyzed for demographic, radiographic, anatomic, histologic, genomic, epigenetic, and transcriptional characteristics.

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The synthesis and biological evaluation of the new cholestane glycoside (25R)-3β,16β-diacetoxy-22-oxocholest-5-en-26-yl β-d-glucopyranoside starting from diosgenin is described. This compound showed selective antiproliferative activity against CaSki, ViBo, and HeLa cervicouterine cancer cells. Its effect on the cell-cycle was determined.

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Inhibition of intestinal α-glucosidases and pancreatic α-amylases is an approach to controlling blood glucose and serum insulin levels in individuals with Type II diabetes. The two human intestinal glucosidases are maltase-glucoamylase and sucrase-isomaltase. Each incorporates two family 31 glycoside hydrolases responsible for the final step of starch hydrolysis.

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The proto-oncogenes ETV1, ETV4 and ETV5 encode transcription factors in the E26 transformation-specific (ETS) family, which includes the most frequently rearranged and overexpressed genes in prostate cancer. Despite being critical regulators of development, little is known about their post-translational regulation. Here we identify the ubiquitin ligase COP1 (also known as RFWD2) as a tumour suppressor that negatively regulates ETV1, ETV4 and ETV5.

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The viral neuraminidase enzyme is an established target for anti-influenza pharmaceuticals. However, viral neuraminidase inhibitors could have off-target effects due to interactions with native human neuraminidase enzymes. We report the activity of a series of known inhibitors of the influenza group-1 neuraminidase enzyme (N1 subtype) against recombinant forms of the human neuraminidase enzymes NEU3 and NEU4.

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We have recently demonstrated that newly synthesized oseltamivir derivatives that contain a substituted triazole ring at the C-5 amino group interact with the 150 cavity found specifically in the group-1 neuraminidase (NA) subtypes of influenza A virus. These compounds exhibited in vitro inhibition activity of a group-1 NA enzyme incorporated in virus-like particles (VLPs). In the current study, we tested these nine triazole-containing carbocycles as well as an amino- and a guanidino-substituted derivative in virus replication inhibitory assays in vitro.

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The primary function of B cells, critical components of the adaptive immune response, is to produce antibodies against foreign antigens, as well as to perform isotype class switching, which changes the heavy chain of an antibody so that it can interact with different repertoires of effector cells. CD40 is a member of the tumor necrosis factor superfamily of cell surface receptors that transmits survival signals to B cells. In contrast, in B cell cancers, stimulation of CD40 signaling results in a heterogeneous response in which cells can sometimes undergo cell death in response to treatment, depending on the system studied.

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In order to probe the active-site requirements of the human N-terminal subunit of maltase-glucoamylase (ntMGAM), one of the clinically relevant intestinal enzymes targeted for the treatment of type-2 diabetes, the syntheses of two new inhibitors are described. The target compounds are structural hybrids of kotalanol, a naturally occurring glucosidase inhibitor with a unique five-membered ring sulfonium-sulfate inner salt structure, and miglitol, a six-membered ring antidiabetic drug that is currently in clinical use. The compounds comprise the six-membered ring of miglitol and the side chain of kotalanol or its de-O-sulfonated derivative.

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We report here the exploitation of the 150-cavity in the active sites of group-1 neuraminidases for the design of new triazole-containing carbocycles related to oseltamivir. Inhibition studies with virus-like particles (VLPs) containing the influenza virus neuraminidase-1 (N1) activity indicate that several candidates are inhibitors, with K(i) values in the 10(-5)-10(-8) M range. In contrast, a known candidate that preserves the free amino group and a new candidate containing a guanidine function are better inhibitors, with K(i) values of 1.

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The synthesis of the new glycoside (25R)-3β,16β-diacetoxy-12,22-dioxo-5α-cholestan-26-yl β-D-glucopyranoside starting from hecogenin is described. This compound showed anti-cancer activity against cervicouterine cancer cells HeLa, CaSki and ViBo in the micromolar range. Its effect on cell proliferation, cell cycle and cell death is also described.

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