Molecular characterization of the putative oncogene myeov

The myeov gene was identified using the tumorigenicity assay with DNA from a patient suffering a gastric carcinoma. The Myeov gene is localized at chromosome band 11q13, a frequent site for chromosomal rearrangements in various carcinomas and B-cell neoplasms. The gene was shown to be involved in cases of multiple myeloma harboring the t(11;14)(q13;q32). In addition, myeov is coamplified with cyclin D1 and overexpressed in carcinomas of the breast, lung, bladder, esophageal squamous cell carcinomas and oral squamous cell carcinomas. Myeov DNA amplification and overexpression was detected in several carcinoma cell lines, however, hardly any MYEOV protein could be detected using specific antibodies in Western blot analysis. The 5 untranslated region (5UTR) of the myeov gene is long, encompasses four upstream AUG codons (uAUGs) and is predicted to fold in a strong secondary structure. These features are common among mRNAs regulated by their 5UTR and suggest that MYEOV protein synthesis might be regulated at a posttranscriptional level. These findings prompted us to investigate the possible role of the myeov 5UTR in controlling its protein level, and the possibility of MYEOV protein synthesis to be mediated by an internal ribosome entry site (IRES). Here we show that initial experiments using mono- and bicistronic reporter constructs supported this view. However, further examination by in vitro transcription/translation assays, Northern blot analysis and the application of promoterless constructs revealed promoter activity in the myeov 5UTR. Despite this strong promoter activity, we did not find any translation products. Our experiments showed that this was due to the presence of uAUGs codons present in the myeov 5UTR. DNA and RNA transfection of the wild type and mutated 5UTR, where the uAUGs were mutated to AAG, confirmed that these uAUGs abrogate translation of the reporter gene as well as the myeov gene. Alternative splicing mechanisms in specific cell types and/or developmental stages may be a way to evade this translation control. %%%%Das Myeov Gen wurde mittels eines Tumorigenizitatsassays aus der DNA eines Patienten mit einem Magentumor isoliert. Das Gen ist auf der Chromosomenbande 11q13 lokalisiert worden, einem haufig betroffenen Abschnitt fur chromosomale Rekombinationen in verschiedenen Karzinomen und B-Zell-Neoplasien. Es ist nachweislich an Fallen multipler Myelome beteiligt, die eine t(11;14)(q13;q32) zeigen. Auch findet man Myeov zusammen mit Cyclin D1 koamplifiziert und uberexprimiert in Karzinomen der Brust, der Lunge, der Blase, sowie in Epithelzellkarzinomen des Osophagus und der Mundhohle. Amplifikation und Uberexpression von MYEOV wurden zwar in mehreren Karzinom-Zelllinien gezeigt, jedoch konnte in der Western-Blot-Analyse mit myeov-spezifischen Antikorpern kein Protein nachgewiesen werden. Die 5 nichttranslatierte Region (5UTR) des Myeov-Gens ist relativ lang, sie enthalt vier vorgeschaltete AUG Kodons (uAUGs) und ist laut Prognose eines Computerprogramms in der Lage, eine starke Sekundarstruktur…