Carcinogenic Effects in a Phenylketonuria Mouse Model

Phenylketonuria (PKU) is a metabolic disorder caused by impaired phenylalanine hydroxylase (PAH). This condition results in hyperphenylalaninemia and elevated levels of abnormal phenylalanine metabolites, among which is phenylacetic acid/phenylacetate (PA). In recent years, PA and its analogs were found to have anticancer activity against a variety of malignancies suggesting the possibility that PKU may offer protection against cancer through chronically elevated levels of PA. We tested this hypothesis in a genetic mouse model of PKU (PAHenu2) which has a biochemical profile that closely resembles that of human PKU. Plasma levels of phenylalanine in homozygous (HMZ) PAHenu2 mice were >12-fold those of heterozygous (HTZ) littermates while tyrosine levels were reduced. Phenylketones, including PA, were also markedly elevated to the range seen in the human disease. Mice were subjected to 7,12 dimethylbenz[a]anthracene (DMBA) carcinogenesis, a model which is sensitive to the anticancer effects of the PA derivative 4-chlorophenylacetate (4-CPA). Tumor induction by DMBA was not significantly different between the HTZ and HMZ mice, either in total tumor development or in the type of cancers that arose. HMZ mice were then treated with 4-CPA as positive controls for the anticancer effects of PA and to evaluate its possible effects on phenylalanine metabolism in PKU mice. 4-CPA had no effect on the plasma concentrations of phenylalanine, phenylketones, or tyrosine. Surprisingly, the HMZ mice treated with 4-CPA developed an unexplained neuromuscular syndrome which precluded its use in these animals as an anticancer agent. Together, these studies support the use of PAHenu2 mice as a model for studying human PKU. Chronically elevated levels of PA in the PAHenu2 mice were not protective against cancer

Location analysis for the estrogen receptor-α reveals binding to diverse ERE sequences and widespread binding within repetitive DNA elements

Location analysis for estrogen receptor-α (ERα)-bound cis-regulatory elements was determined in MCF7 cells using chromatin immunoprecipitation (ChIP)-on-chip. Here, we present the estrogen response element (ERE) sequences that were identified at ERα-bound loci and quantify the incidence of ERE sequences under two stringencies of detection: <10% and 10–20% nucleotide deviation from the canonical ERE sequence. We demonstrate that ∼50% of all ERα-bound loci do not have a discernable ERE and show that most ERα-bound EREs are not perfect consensus EREs. Approximately one-third of all ERα-bound ERE sequences reside within repetitive DNA sequences, most commonly of the AluS family. In addition, the 3-bp spacer between the inverted ERE half-sites, rather than being random nucleotides, is C(A/T)G-enriched at bona fide receptor targets. Diverse ERα-bound loci were validated using electrophoretic mobility shift assay and ChIP-polymerase chain reaction (PCR). The functional significance of receptor-bound loci was demonstrated using luciferase reporter assays which proved that repetitive element ERE sequences contribute to enhancer function. ChIP-PCR demonstrated estrogen-dependent recruitment of the coactivator SRC3 to these loci in vivo. Our data demonstrate that ERα binds to widely variant EREs with less sequence specificity than had previously been suspected and that binding at repetitive and nonrepetitive genomic targets is favored by specific trinucleotide spacers

Actions of Retinoic Acid in the Pathophysiology of HIV Infection

The vitamin A metabolite all-trans retinoic acid (RA) plays a key role in tissue homeostasis and mucosal immunity. RA is produced by gut-associated dendritic cells, which are among the first cells encountered by HIV. Acute HIV infection results in rapid reduction of RA levels and dysregulation of immune cell populations whose identities and function are largely controlled by RA. Here, we discuss the potential link between the roles played by RA in shaping intestinal immune responses and the manifestations and pathogenesis of HIV-associated enteropathy and similar conditions observed in SIV-infected non-human primate models. We also present data demonstrating the ability of RA to enhance the activation of replication-competent viral reservoirs from subjects on suppressive anti-retroviral therapy. The data suggest that retinoid supplementation may be a useful adjuvant for countering the pathologic condition of the gastro-intestinal tract associated with HIV infection and as part of a strategy for reactivating viral reservoirs as a means of depleting latent viral infection

Adult intralesional cidofovir therapy for laryngeal papilloma: A 10-year perspective

Objective: To assess the long-term efficacy of intralesional cidofovir therapy in a previously reported cohort of adult subjects with laryngeal papilloma. Design: Retrospective review. Setting: Tertiary care medical center. Patients: We previously reported on the favorable clinical response to intralesional cidofovir therapy in 13 adult subjects. The subjects were enrolled in an opentrial prospective study (1997-2001) and completed the injection-only treatment protocol, and all subjects achieved a disease remission after a mean of 6 injections. In the present study, we review the clinical course of these subjects during an extended observational period (2001-2006). Intervention: Patients with documented relapse of disease underwent additional intralesional cidofovir injections. Main Outcome Measures: Additional interventions, disease severity, and adverse outcomes are reported. Results: Following the original cidofovir protocol, 6 patients (46%) received no further interventions. The remaining 7 patients (54%) required further treatment for disease relapse, with a mean duration of remission before relapse of 1.05 years. Of the 7 patients who experienced disease relapse, 2 continued to have stable disease with regular injections, 2 were lost to follow-up during relapse treatment, and 3 achieved disease remission again. For this latter cohort, the mean number of injections per year necessary to achieve a second remission was 3.82. This compares with a mean of 1.77 injections per year that these patients received on an as-needed basis prior to the original study. Conclusion: Intralesional cidofovir injections have been shown to be an effective therapy for adult laryngeal papilloma and should be considered in those patients who experience disease relapse. ©2008 American Medical Association. All rights reserved

Tumor development.

<p>Female HTZ and HMZ PAH^enu2 mice as indicated were subcutaneously implanted with a slow releasing MPA pellet at approximately 5 weeks of age, then treated with DMBA p.o. (1 mg/mouse) approximately 2 weeks later. Mice were given a total of 4 treatments of DMBA (one/week for 4 weeks). Tumor development in mice was assessed as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004292#s3" target="_blank">Materials and Methods</a>.</p