PLAG1 activation in lipoblastoma coinciding with low-level amplification of a derivative chromosome 8 with a deletion del(8)(q13q21.2)

Abstract

Lipoblastoma is a benign uncommon soft-tissue-tumor resembling fetal adipose tissue affecting mainly children under three years of age. In lipoblastoma, the typical cytogenetic changes are clonal rearrangements involving chromosomal region 8q11→q13. The oncogene PLAG1 (pleomorphic adenoma gene 1) is located within this chromosomal region on band 8q12. Recent reports have demonstrated that in lipoblastoma, the PLAG1 gene is activated by ‘promoter-swapping’. Herein, we demonstrate that in lipoblastoma, the PLAG1 gene may also be activated by low-level amplification. We report on a lipoblastoma with the karyotype 48∼50,XX,del(8)(q13q21.2),+del(8)(q13q21.2)×4[cp12]. Subsequent FISH analysis on uncultured tumor cells confirmed this result and demonstrated a low-level amplification of the chromosomal region 8pter→8q13 and 8q21.2→8qter. A partial monosomy was seen for the chromosomal region 8q13→8q21.2. No other gains or losses were observed by CGH analysis. RT-PCR analysis showed that the PLAG1 gene is activated in the tumor sample of the lipoblastoma analyzed, in contrast to normal fatty tissue without PLAG1 expression. In conclusion, our results demonstrate that low-level amplification is a further mechanism of PLAG1 activation in lipoblastomas.