Gunnar Wrobel — Page 2

PubMed2002

Classical Hodgkin lymphoma is characterized by recurrent copy number gains of the short arm of chromosome 2.

Hodgkin- and Reed-Sternberg (HRS) cells microdissected from 41 classical Hodgkin lymphomas (cHL) of 40 patients comprising 8 lymphocyte-rich (cHL-LR), 16 nodular sclerosis (cHL-NS), 15 mixed-cellularity (cHL-MC), and 2 lymphocyte-depletion (cHL-LD) subtypes were analyzed by comparative genomic hybridization for recurrently imbalanced chromosomal subregions. Chromosomal gains most frequently involved chromosome 2p (54%), 12q (37%), 17p (27%), 9p and 16p (24% each), and 17q and 20q (20% each), whereas losses primarily affected chromosome 13q (22%). Using fluorescence in situ hybridization, amplification of the REL oncogene was demonstrated within a distinct 2p15-p16 amplicon. The high frequency of 2p overrepresentations including REL, particularly in cHL-NS (88%), suggests that an alternative mechanism of constitutive activation of nuclear factor NF-kappaB is a hallmark of HRS cells. Hierarchical cluster analysis of chromosomal imbalances revealed a closer relationship among cHL-NS than other subtypes. Furthermore, there is a tendency for different subtypes of cHL-MC tumors characterized by different ages at the time of tumor onset and gain of chromosome 17p. The imbalance pattern of cHL subtypes suggests that different molecular pathways are activated, with REL or other genes on chromosomal band 2p15-p16 playing a fundamental role in the pathogenesis of classical Hodgkin lymphoma.

Adolescent↗

PubMed2002

Automated screening for genomic imbalances using matrix-based comparative genomic hybridization.

Genome-wide screening for chromosomal imbalances using comparative genomic hybridization (CGH) revealed a wealth of data on previously unrecognized tumor-specific genomic alterations. CGH to microarrays of DNA, an approach termed matrix-CGH, allows detection of genomic imbalances at a much higher resolution. We show that matrix CGH is also feasible from small tissue samples requiring universal amplification of genomic DNA. Because widespread application of matrix-CGH experiments using large numbers of DNA targets demands a high degree of automation, we have developed a protocol for a fully automated procedure. The use of specialized instrumentation for the generation of DNA chips, their hybridization, scanning, and evaluation required numerous alterations and modifications of the initial protocol. We here present the elaboration and testing of automated matrix-CGH. A chip consisting of 188 different genomic DNA fragments, cloned in bacterial artificial chromosome (BAC) or P1-derived artificial chromosome (PAC) vectors and immobilized in replicas of 10, was used to assess the performance of the automated protocol in determining the gene dosage variations in tumor cell lines COLO320-HSR, HL60, and NGP. Although ratios of matrix-CGH were highly concordant with results of chromosomal CGH (85%), the dynamic range of the matrix-CGH ratios was highly superior. Investigation of the two amplicons on 8q24 in COLO320-HSR and HL60, containing the MYC gene, revealed a homogeneous amplicon in COLO320-HSR but a heterogeneous amplification pattern in HL60 cells. Although control clones for normalization of the signal ratios can be predicted in cases with defined chromosomal aberrations, in primary tumors such data are often not available, requiring alternative normalization algorithms. Testing such algorithms in a primary high-grade B-cell lymphoma, we show the feasibility of this approach. With the matrix-CGH protocol presented here, robust and reliable detection of genomic gains and losses is accomplished in an automated fashion, which provides the basis for widespread application in tumor and clinical genetics.

Chromosome Aberrations↗