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Retinoic acid pathway activity in Wilms tumors and characterization of biological responses in vitro

ABSTRACT: Wilms tumor (WT) is one of the most common malignancies in childhood. With current therapy protocols up to 90 % of patients can be cured, but there is still a need to improve therapy for patients with aggressive WT and to reduce treatment intensity where possible. Prior data suggested deregulation of the retinoic acid (RA) pathway in high-risk WT. This could be validated in a large independent tumor set. Reduced RA pathway activity and MYCN overexpression were found in high risk tumors as opposed to tumors with low/intermediate risk, suggesting a beneficial impact of RA on advanced WT. To investigate the possible mode of action of retinoids as a novel therapeutic agent we treated primary tumor cell cultures with all-trans-RA (ATRA), 9cis-RA, fenretinide and combinations of retinoids and a histone deacetylase (HDAC) inhibitor. Genes deregulated in high risk tumors showed opposite changes upon treatment suggesting a positive effect of retinoids. 6/7 primary cultures tested reduced proliferation, irrespective of prior RA signaling levels. The only variant culture was derived from mesoblastic nephroma, a distinct childhood kidney neoplasm. Retinoid / HDAC inhibitor combinations provided no synergistic effect. ATRA and 9cis-RA induced morphological changes suggestive of differentiation, while fenretinide induced apoptosis in several cultures tested. Microarray analysis of ATRA treated WT cells revealed differential expression of many genes involved in extracellular matrix formation and osteogenic, neuronal or muscle differentiation. Although some of the effects appear to be reversible, these findings provide further evidence of a potential utility of retinoids in Wilms tumor treatment.

ORGANISM(S): Homo sapiens

PROVIDER: GSE28807 | GEO | 2012/04/21

SECONDARY ACCESSION(S): PRJNA138801

REPOSITORIES: GEO

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Project description:Targets of Retinoic Acid (RA) and 3,4-didehydroretinoic acid (ddRA) were identified in primary human epidermal keratinocytes grown in the presence of atRA or ddRA for 4 and 24 hours. Retinoids (natural forms and synthetic derivatives of vitamin A) are used as therapeutic agents for numerous skin diseases such as keratinization disorders (e.g. ichthyoses) and psoriasis. Two endogenous ligands for retinoic acid receptors exist, retinoic acid (atRA) and 3,4-didehydroretinoic acid (ddRA). In primary human epidermal keratinocytes many transcriptional targets for atRA are known, whereas the targets for ddRA are unknown. In an attempt to determine the targets, we compared the effect of atRA and ddRA on transcriptional profiles in undifferentiated and differentiating human primary keratinocytes. First, as expected, many genes were induced or suppressed in response to keratinocyte differentiation. Furthermore, the two retinoids affected substantially more genes in differentiated keratinocytes (more than 350) than in proliferating keratinocytes (20). In differentiating keratinocytes markers of cornification were suppressed suggesting a de-differentiating effect by the two retinoids. When comparing the expression profile of atRA to that of ddRA, no differently regulated genes were found. The array analysis also found that a minor number of miRNAs and a large number of non-coding transcripts were changed during differentiation and in response to the two retinoids. Furthermore, the expression of all, except one, genes known to cause autosomal recessive congenital ichthyosis (ARCI) were found to be induced by differentiation. These results comprehensively document that atRA and ddRA exert similar transcriptional changes in keratinocytes and also add new insights into the molecular mechanism influenced by retinoids in the epidermis. Furthermore, it suggests which ARCI patients could benefit from therapy with retinoids. Proliferating and differentiated keratinocytes were harvested after 4 and 24 hours after treatment with atRA, ddRA and vehicle for RNA extraction and hybridization on Affymetrix microarrays. Triplicate samples were generated for each time point and each treatment.

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Retinoic acid pathway activity in Wilms tumors and characterization of biological responses in vitro

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