Chromosome 9p21 gene copy number and prognostic significance of p16 in ESFT

Chromosome 9p21 gene copy number in Ewing's sarcoma family of tumour (ESFT) cell lines and primary ESFT has been evaluated using Multiplex Ligation-dependent probe amplification, and the clinical significance of CDKN2A loss and p16/p14ARF expression investigated. Homozygous deletion of CDKN2A was identified in 4/9 (44%) of ESFT cell lines and 4/42 (10%) primary ESFT; loss of one copy of CDKN2A was identified in a further 2/9 (22%) cell lines and 2/42 (5%) tumours. CDKN2B was co-deleted in three (33%) cell lines and two (5%) tumours. Co-deletion of the MTAP gene was observed in 1/9 (11%) cell lines and 3/42 (7%) tumours. No correlation was observed between CDKN2A deletion and clinical parameters. However, co-expression of high levels of p16/p14ARF mRNA predicted a poor event-free survival (P=0.046, log-rank test). High levels of p16/p14ARF mRNA did not correlate with high expression of p16 protein. Furthermore, p16 protein expression did not predict event-free or overall survival. Methylation is not a common mechanism of p16 gene silencing in ESFT. These studies demonstrate that loss (homozygous deletion or single copy) of CDKN2A was not prognostically significant in primary ESFT. However, high levels of p16/p14ARF mRNA expression were predictive of a poor event-free survival and should be investigated further

Refinement of 1p36 Alterations Not Involving PRDM16 in Myeloid and Lymphoid Malignancies

Fluorescence in situ hybridization was performed to characterize 81 cases of myeloid and lymphoid malignancies with cytogenetic 1p36 alterations not affecting the PRDM16 locus. In total, three subgroups were identified: balanced translocations (N = 27) and telomeric rearrangements (N = 15), both mainly observed in myeloid disorders; and unbalanced non-telomeric rearrangements (N = 39), mainly observed in lymphoid proliferations and frequently associated with a highly complex karyotype. The 1p36 rearrangement was isolated in 12 cases, mainly myeloid disorders. The breakpoints on 1p36 were more widely distributed than previously reported, but with identifiable rare breakpoint cluster regions, such as the TP73 locus. We also found novel partner loci on 1p36 for the known multi-partner genes HMGA2 and RUNX1. We precised the common terminal 1p36 deletion, which has been suggested to have an adverse prognosis, in B-cell lymphomas [follicular lymphomas and diffuse large B-cell lymphomas with t(14;18)(q32;q21) as well as follicular lymphomas without t(14;18)]. Intrachromosomal telomeric repetitive sequences were detected in at least half the cases of telomeric rearrangements. It is unclear how the latter rearrangements occurred and whether they represent oncogenic events or result from chromosomal instability during oncogenesis

EWSR1 (Ewing sarcoma region 1)

Review on EWSR1 (Ewing sarcoma region 1), with data on DNA, on the protein encoded, and where the gene is implicated

Ten novel 11q23 chromosomal partner sites. European 11q23 Workshop participants.

The MLL gene located at 11q23 has been described as a 'promiscuous' gene due its involvement with a large number of genetic partners. The EU Concerted Action Workshop on 11q23 provided 550 cases for study of which 82 showed abnormalities which did not involve the established translocations or deletion of 11q23. In these 'other' cases, which included inversions and duplications, 11q23 was found to be involved with 25 chromosome partners of which 10 had not been previously reported. These were 1q31, 4p11, 6q13, 8q21, 10q22, 10q25, 11q11, 11q21, 13q34 and 18q23. This study demonstrated the value of the Workshop, in confirming the diversity of chromosomal partner sites involved with 11q23 and in the identification of new partners