Amplification and Overexpression of the Dual-specificity Tyrosine-(Y)-phosphorylation Regulated Kinase 2 (DYRK2) Gene in Esophageal and Lung Adenocarcinomas

Genomic amplification can lead to the activation of cellular proto-oncogenes during tumorigenesis, and is observed in most, if not all, human malignancies, including adenocarcinomas of lung and esophagus. Using a two-dimensional restriction landmark genomic scanning technique, we identified five NotI/HinfI fragments with increased genomic dosage in an adenocarcinoma of the gastroesophageal junction. Four of these amplified fragments were matched within three contigs of chromosome 12 using the bioinformatics tool, Virtual Genome Scan. All three of the contigs map to the 12q13-q14 region, and the regional amplification in the tumor was verified using comparative genomic hybridization analysis. The 12q14 amplicon was characterized using sequence tagged site-amplification mapping with DNA from paired normal-tumor tissues of 75 gastroesophageal and 37 lung adenocarcinomas. The amplicon spans a region of >12 Mb between genes DGKA and BLOV1. The core-amplified domain was determined to be <0.5 Mb between marker WI-12457 and gene IFNG. However, MDM2, a well-documented oncogene of the region, is outside the core-domain. Eleven genes and expressed sequence tags within the amplicon were selected for quantitative reverse transcription-PCR, and DYRK2, a member of the dual-specificity kinase family, was overexpressed in all of the tumors showing gene amplification. Among the sequence tagged site/expressed sequence tag/gene markers tested, DYRK2 demonstrated the highest DNA copy number and the highest level of mRNA overexpression in the tumors. Moreover, DYRK2 mRNA overexpression (>2.5-fold of normal mean) was found in 18.6% of additional 86 lung adenocarcinomas in an assay using oligonucleotide microarrays. DYRK2 mRNA overexpression occurs more frequently than gene amplification in both esophageal and lung adenocarcinomas. This is the first report of amplification and overexpression of DYRK2 in any tumor type.