Gene Expression Profile of Acute Myeloid Leukemia (AML) with t(8;16)(p11;p13) and MYST3/CREBBP Rearrangement.

Abstract

Translocation t(8;16)(p11;p13) is an infrequent chromosomal abnormality in de novo and secondary AML cases, leading to the fusion of MYST3 (MOZ) and CREBBP (CBP) genes, both of them harboring histone lysine acetyl-transferase activity. This AML variety displays specific clinical and biological features, although its gene expression profile is currently unknown. In this study, the genetic signature of AML cases with MYST3/CREBBP rearrangement was compared with the genetic profile of other well-defined AML subtypes. Genotypic analyses using oligonucleotide U133A arrays (Affymetrix) were performed on RNA of 19 AML samples, including t(8;16)-AML (n=3), t(15;17) (n=3), t(8;21) (n=2), inv(16)/t(16;16) (n=3), t(9;11) with AF9/MLL rearrangement (n=2), 3 cases with normal karyotype and flt-3 internal tandem duplication (flt-3 ITD), the three remaining samples corresponding to monocytic cases (M4/M5) without MLL rearrangement nor flt-3 ITD. After unsupervised analysis, cases of AML with t(8;16) clustered together, displaying a differential expression profile. Supervised analysis allowed the identification of the top 53 up-regulated and 28 down-regulated genes. Among the set of genes overexpressed, genes involved in chromatin remodelling and transcription (HOXA9, HOXA10, MEIS1, CHD3, SATB1) and protooncogenes (RET, flt-3, LMO2) were identified. In contrast, CREBBP gene and several members of the JAK-STAT pathway (STAT3, STAT5B, JAK2) were underexpressed. Interestingly, overexpression of multiple homeobox genes was detected in flt-3 ITD cases, some of them as a distinctive finding (HOXA2, HOXA3, HOXB6), and others (HOXA9, HOXA10, MEIS1) were found to be highly expressed in MYST3/CREBBP and MLL-rearranged samples. In conclusion, AML with t(8;16) and MYST3/CREBBP rearrangement shows a distinctive gene expression profile, with some similarities with MLL rearranged leukemias and flt-3 ITD AML cases, thus suggesting a partially common leukemogenic pathway.