MLL2, the second human homolog of the Drosophila trithorax gene, maps to 19q13.1 and is amplified in solid tumor cell lines

The Mixed Lineage Leukemia (MLL) gene is commonly involved in translocation s in infantile leukemia and is amplified in some cases of adult myeloid leu kemia. A homolog of MLL denoted MLL2, which represents the second human hom olog of the Drosophila trithorax gene, was characterized by assembling ESTs , the KIAA0304 cDNA clone, RT-PCR fragments and a new clone isolated from a cDNA phage library and compared to the available genomic sequence. The MLL 2 gene maps to 19q13.1, a region of frequent rearrangement or amplification in solid tumors. MLL2 consists of an 8.5-9 kb transcript and spans 20 kb o f genomic DNA, The predicted MLL2 protein possesses all of the major domain s defined in MLL and the two genes have a similar genomic structure. We fin d that MLL2 is amplified in two of 14 pancreatic carcinoma cell lines and o ne of five glioblastoma cell lines and is a likely critical gene in 19q13.1 amplifications. It is also a candidate for chromosomal rearrangements invo lving this chromosome locus, MLL2 is one additional mammalian trithorax-gro up gene with involvement in human cancer.