Transcriptional activation of HMGI-C in three pulmonary hamartomas each with a der(14) t(12; 14) as the sole cytogenetic abnormality

Aberrations involving the chromosomal region 12q14–15 are non-random cytogenetic abnormalities in many benign tumors, e.g. pulmonary chondroid hamartomas (PCH). Recently, we identified rearrangements of the HMGI-C gene within the third or fourth intron as the molecular mechanism underlying most of these chromosomal aberrations. Herein we report our FISH and RACE studies on three PCHs each showing a rare variant type of the translocation t(12;14)(q14–15;q24) with presence of two normal chromosomes 12 and a der(14) but missing the der(12). The results revealed that in all three cases the breakpoint is located 5′ to HMGI-C, suggesting that besides intragenic rearrangements also transcriptional activation of the gene can initiate tumor growth.