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Frederick, MD, United States

Henrich C.J.,U.S. National Cancer Institute | Henrich C.J.,Frederick National Laboratory for Cancer Research | Budhu A.,U.S. National Cancer Institute | Yu Z.,U.S. National Cancer Institute | And 7 more authors.
Chemical Biology and Drug Design | Year: 2013

The cancer stem cell marker, EpCAM, is an important indicator of Wnt/β-catenin signaling activation and a functional component of hepatocellular tumor-initiating cells. A high-throughput screening assay was developed to identify inhibitors of EpCAM-dependent growth of hepatocellular carcinoma (HCC) cells. EpCAM(+) and EpCAM(-) HCC cell lines were assessed for differential sensitivity to a Wnt/β-catenin pathway inhibitor. Libraries comprising 22 668 pure compounds and 107 741 crude or partially purified natural product extracts were tested, and 12 pure compounds and 67 natural product extracts were identified for further study. Three active compounds and the positive control were further characterized in terms of effects on EpCAM expression. Treatment of EpCAM(+) Hep3B cells resulted in loss of EpCAM expression as assessed by flow cytometry. This reduction was incomplete (most cells continued to express EpCAM), but resulted in generation of cell populations expressing lower levels of EpCAM. Sublethal concentrations (~IC50) reduced median EpCAM expression to 28% of control after 1 day and 19% of control after 2 days. Reduction in EpCAM expression preceded growth inhibition suggesting that a threshold of EpCAM expression may be required for growth of EpCAM-dependent cells. The identification of compounds with a variety of possible molecular targets suggests a likelihood of multiple mechanisms for modulation of EpCAM-dependent cell growth. The cancer stem cell marker, EpCAM, is an important indicator of Wnt-β-catenin signaling activation and a functional component of hepatocellular tumor initiating cells. A high-throughput screening assay idenified inhibitors of EpCAM-dependent growth of hepatocellular carcinoma cells. Several of these inhibitors were found to concomitantly inhibit expression of surface EpCAM, consisent with a requirement of EpCAM expression for continued cell growth. Further development inhibitors will provide additional insight into control of EpCAM expression and characteristics of hepatocellular cancer stem cells.© 2013 John Wiley and Sons A/S. Source


Del Prete G.Q.,Laboratory Animal science Program | Oswald K.,Laboratory Animal science Program | Lara A.,Laboratory Animal science Program | Shoemaker R.,Laboratory Animal science Program | And 21 more authors.
Antimicrobial Agents and Chemotherapy | Year: 2016

Replication-competent human immunodeficiency virus (HIV) persists in infected people despite suppressive combination antiretroviral therapy (cART), and it represents a major obstacle to HIV functional cure or eradication. We have developed a model of cART-mediated viral suppression in simian human immunodeficiency virus (SIV) mac239-infected Indian rhesus macaques and evaluated the impact of the histone deacetylase inhibitor (HDACi) romidepsin (RMD) on viremia in vivo. Eight macaques virologically suppressed to clinically relevant levels (>30 viral RNA copies/ml of plasma), using a three-class five-drug cART regimen, received multiple intravenous infusions of either RMD (n5) or saline (n3) starting 31 to 54 weeks after cART initiation. In vivo RMD treatment resulted in significant transient increases in acetylated histone levels in CD4T cells. RMD-treated animals demonstrated plasma viral load measurements for each 2-week treatment cycle that were significantly higher than those in saline control-treated animals during periods of treatment, suggestive of RMD-induced viral reactivation. However, plasma virus rebound was indistinguishable between RMD-treated and control-treated animals for a subset of animals released from cART. These findings suggest that HDACi drugs, such as RMD, can reactivate residual virus in the presence of suppressive antiviral therapy and may be a valuable component of a comprehensive HIV functional cure/eradication strategy. Copyright © 2016, American Society for Microbiology. All Rights Reserved. Source


Del Prete G.Q.,Laboratory Animal science Program | Shoemaker R.,Laboratory Animal science Program | Oswald K.,Laboratory Animal science Program | Lara A.,Laboratory Animal science Program | And 21 more authors.
Antimicrobial Agents and Chemotherapy | Year: 2014

Nonhuman primate models are needed for evaluations of proposed strategies targeting residual virus that persists in HIV-1- infected individuals receiving suppressive combination antiretroviral therapy (cART). However, relevant nonhuman primate (NHP) models of cART-mediated suppression have proven challenging to develop. We used a novel three-class, six-drug cART regimen to achieve durable 4.0- to 5.5-log reductions in plasma viremia levels and declines in cell-associated viral RNA and DNA in blood and tissues of simian immunodeficiency virus SIVmac239-infected Indian-origin rhesus macaques, then evaluated the impact of treatment with the histone deacetylase inhibitor (HDACi) suberoylanilide hydroxamic acid (SAHA; Vorinostat) on the residual virus pool. Ex vivo SAHA treatment of CD4 T cells obtained from cART-suppressed animals increased histone acetylation and viral RNA levels in culture supernatants. cART-suppressed animals each received 84 total doses of oral SAHA. We observed SAHA dose-dependent increases in acetylated histones with evidence for sustained modulation as well as refractoriness following prolonged administration. In vivo virologic activity was demonstrated based on the ratio of viral RNA to viral DNA in peripheral blood mononuclear cells, a presumptive measure of viral transcription, which significantly increased in SAHAtreated animals. However, residual virus was readily detected at the end of treatment, suggesting that SAHA alone may be insufficient for viral eradication in the setting of suppressive cART. The effects observed were similar to emerging data for repeat-dose SAHA treatment of HIV-infected individuals on cART, demonstrating the feasibility, utility, and relevance of NHP models of cART-mediated suppression for in vivo assessments of AIDS virus functional cure/eradication approaches. © 2014, American Society for Microbiology. All Rights Reserved. Source


Shiao Y.-H.,Frederick National Laboratory for Cancer Research | Leighty R.M.,Data Management Services Inc. | Wang C.,Frederick National Laboratory for Cancer Research | Ge X.,SAIC | And 13 more authors.
Environmental and Molecular Mutagenesis | Year: 2012

Both gene methylation changes and genetic instability have been noted in offspring of male rodents exposed to radiation or chemicals, but few specific gene targets have been established. Previously, we identified the gene for ribosomal RNA, rDNA, as showing methylation change in sperm of mice treated with the preconceptional carcinogen, chromium(III) chloride. rDNA is a critical cell growth regulator. Here, we investigated the effects of paternal treatments on rDNA in offspring tissue. A total of 93 litters and 758 offspring were obtained, permitting rigorous mixed-effects models statistical analysis of the results. We show that the offspring of male mice treated with Cr(III) presented increased methylation in a promoter sequence of the rDNA gene, specifically in lung. Furthermore polymorphic variants of the multi-copy rDNA genes displayed altered frequencies indicative of structural changes, as a function of both tissue type and paternal treatments. Organismal effects also occurred: some groups of offspring of male mice treated with either Cr(III) or its vehicle, acidic saline, compared with those of untreated mice, had altered average body and liver weights and levels of serum glucose and leptin. Males treated directly with Cr(III) or acidic saline presented serum hormone changes consistent with a stress response. These results establish for the first time epigenetic and genetic instability effects in a gene of central physiological importance, in offspring of male mice exposed preconceptionally to chemicals, possibly related to a stress response in these males. © 2012 Wiley Periodicals, Inc. Source

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