Retained heterodisomy is associated with high gene expression in hyperhaploid inflammatory leiomyosarcoma (Illumina)

ABSTRACT: Inflammatory leiomyosarcoma (ILMS) is a soft tissue tumor that morphologically resembles conventional leiomyosarcoma (LMS) admixed with a prominent inflammatory infiltrate. Genetic data on ILMS are still limited but have suggested that this entity is characterized by hyperhaploidy (24-34 chromosomes). This low chromosome number is otherwise uncommon in neoplasia and has been found only in 0.2-0.3% of cytogenetically investigated tumors. Here, three ILMS were investigated using cytogenetic, SNP array and global gene expression analyses. All cases displayed a hyperhaploid origin. Combined with previously reported cases, hyperhaploidy has been found in six of seven cytogenetically investigated ILMS. The copy number distribution of individual chromosomes is clearly nonrandom; the hyperhaploid clones of all six cases displayed disomy for chromosomes 5 and 20, and two copies of chromosomes 18, 21 and 22 were also common. All chromosomes identified as disomic showed a biparental origin by SNP array analysis; whether this is of pathogenetic importance is not known. Compared with conventional LMS, ILMS had a distinct gene expression signature. Furthermore, the number of chromosome copies correlated well with gene expression levels, a finding which has not previously been reported for hyperhaploid tumors. Genes on disomic chromosomes showed higher expression levels in ILMS compared to LMS and disomic chromosomes showed higher average gene expression levels than monosomic chromosomes. Taken together, our findings suggest that disomy for some chromosomes, notably 5 and 20, as well as distorted gene expression balance achieved through massive loss of other chromosomes are essential for the development of ILMS. Tumor DNA was hybridized onto Illumina Human CNV370-Quad v3_C (case 1) and Illumina Human CNV370 v1_C (cases 2 and 3) BeadChips, containing ~370,000 markers, following standard protocols supplied by the manufacturer (Illumina). Data analysis was performed using the GenomeStudio software (Illumina), detecting imbalances by visual inspection.

ORGANISM(S): Homo sapiens

SUBMITTER: Karolin Nord 

PROVIDER: E-GEOD-38015 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress