ABSTRACT
Pediatric acute myeloid leukemia (AML) is a rare disease whose prognosis is highly variable according to factors such as chromosomal abnormalities. Recurrent genomic rearrangements are detected in half of pediatric AML by karyotype. NUcleoPorin 98 (NUP98) gene is rearranged with 31 different fusion partner genes. These rearrangements are frequently undetected by conventional cytogenetics, as the NUP98 gene is located at the end of the chromosome 11 short arm (11p15). By screening a series of 574 pediatric AML, we detected a NUP98 rearrangement in 22 cases (3.8%), a frequency similar to CBFB-MYH11 fusion gene (4.0%). The most frequent NUP98 fusion gene partner is NSD1. These cases are homogeneous regarding their biological and clinical characteristics, and associated with bad prognosis only improved by bone marrow transplantation. We detailed the biological characteristics of these AML by exome sequencing which demonstrated few recurrent mutations (FLT3 ITD, WT1, CEBPA, NBPF14, BCR and ODF1). The analysis of the clonal structure in these cases suggests that the mutation order in the NUP98-rearranged pediatric AML begins with the NUP98 rearrangement leading to epigenetic dysregulations then followed by mutations of critical hematopoietic transcription factors and finally, activation of the FLT3 signaling pathway.
Subject(s)
Leukemia, Myeloid, Acute/diagnosis , Leukemia, Myeloid, Acute/genetics , Nuclear Pore Complex Proteins/genetics , Translocation, Genetic , Alleles , Biomarkers, Tumor , CCAAT-Enhancer-Binding Proteins/genetics , Child , Child, Preschool , Epigenesis, Genetic , Exome , Female , Gene Expression Regulation, Leukemic , Gene Frequency , High-Throughput Nucleotide Sequencing , Humans , In Situ Hybridization, Fluorescence , Infant , Infant, Newborn , Leukemia, Myeloid, Acute/metabolism , Leukemia, Myeloid, Acute/mortality , Male , Mutation , Oncogene Proteins, Fusion/genetics , Prognosis , Signal Transduction , WT1 Proteins/genetics , fms-Like Tyrosine Kinase 3/metabolismABSTRACT
Myeloproliferative neoplasms are frequently associated with aberrant constitutive tyrosine kinase (TK) activity resulting from chimaeric fusion genes or point mutations such as BCR-ABL1 or JAK2 V617F. We report here the cloning and functional characterization of two novel fusion genes BCR-RET and FGFR1OP-RET in chronic myelomonocytic leukemia (CMML) cases generated by two balanced translocations t(10;22)(q11;q11) and t(6;10)(q27;q11), respectively. The two RET fusion genes leading to the aberrant activation of RET, are able to transform hematopoietic cells and skew the hematopoietic differentiation program towards the monocytic/macrophage lineage. The RET fusion genes seem to constitutively mimic the same signaling pathway as RAS mutations frequently involved in CMML. One patient was treated with Sorafenib, a specific inhibitor of the RET TK function, and demonstrated cytological and clinical remissions.
