Genomic amplification is observed in many, if not all, types of human
malignancy and is one of the mechanisms for the activation of dominant-acting oncogenes in
tumorigenesis. In the present study, three amplified restriction fragments were identified in an esophageal
adenocarcinoma (P16) using the restriction landmark genome scanning two-dimensional gel technique. These fragments were cloned, sequenced, and mapped to chromosome band 14q13. Using the sequence tagged site-amplification mapping approach, we defined the core-amplified domain by screening 75 normal-
tumor paired esophageal samples. The frequency of 14q13 amplification is 6.7% in esophageal
tumors, and the amplicon spans >6 Mb in 1
tumor but is contained in a region <0.3 Mb in all of the remaining amplified
tumors. Quantitative reverse transcription-PCR (RT-PCR) of 8 genes and expressed sequence tags located within the core-amplified domain revealed that the HNF3alpha (FOXA1)(4) gene, a forkhead gene family member, was overexpressed in all of the amplified esophageal
tumors. HNF3alpha amplification was confirmed by Southern blot and interphase fluorescence in situ hybridization analyses, and the results of real-time RT-PCR were consistent with that of the regular quantitative RT-PCR. Increased immunohistochemical nuclear staining of the HNF3alpha
protein was detected in all of the
tumors containing 14q13 amplification. Affymetrix
oligonucleotide microarrays of 86
lung adenocarcinomas demonstrated that expression of the HNF3alpha
mRNA was elevated (> or =2.5-fold of mean expression in normal lung) in 37% (32 of 86) of the
tumors analyzed. Gene amplification of HNF3alpha was detected in 2 of the 5 overexpressed lung
tumors examined. This is the first report of HNF3alpha amplification, and overexpression in esophageal and
lung adenocarcinomas. Amplification of HNF3alpha in esophageal and lung
tumors may suggest a potential oncogenic role for this gene in
tumorigenesis.