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This Article Full Text Full Text (PDF) All Versions of this Article: ERC-08-0060v1 15/3/817    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Zhou, C. Articles by Melmed, S. PubMed PubMed Citation Articles by Zhou, C. Articles by Melmed, S.

Departments of¹ , Medicine² Pathology, David Geffen School of Medicine at UCLA, Cedars-Sinai Medical Center, Los Angeles, California 90048, USA

(Correspondence should be addressed to S Melmed, Cedars-Sinai Research Institute, Room 2015, Los Angeles, California 90048, USA; Email: melmed{at}csmc.edu)

As human pituitary tumor transforming gene (hPTTG1) is upregulated in endocrine tumors, we studied regulatory mechanisms for hPTTG1 expression. We identified Oct-1-binding motifs in the hPTTG1 promoter region and show Oct-1-specific binding to the hPTTG1 promoter using chromatin immunoprecipitation. We overexpressed Oct-1 and observed 2.5-fold activation of hPTTG1 promoter luciferase constructs (–2642/–1 and –1717/–1). Transcriptional activation was abrogated by co-transfection of an inactive Oct-1 form lacking the POU domain or by utilizing mutated hPTTG1 promoters or mutants devoid of two Oct-1-binding motifs (–1717/–1mut, –637/–1 or –433/–1). Using biotin–streptavidin pull-down assays, we confirmed Oct-1 binding to the two octamer motifs in the hPTTG1 promoter (–1669/–1631 and –1401/–1361). Endogenous hPTTG1 mRNA and protein increased up to approximately fourfold in Oct-1 transfectants, as measured by real-time PCR and western blot. In contrast, siRNA-mediated suppression of endogenous Oct-1 attenuated both the hPTTG1 mRNA and protein levels. Using confocal immunofluorescence imaging, Oct-1 and hPTTG1 were concordantly upregulated in pituitary (57 and 62%, n=79, P<0.01) and breast tumor specimens (57 and 42%, n=77, P<0.05) respectively. The results show that Oct-1 transactivates hPTTG1, and both proteins are concordantly overexpressed in endocrine tumors, thus offering a mechanism for endocrine tumor hPTTG1 abundance.