Alain Bernheim

Risk of Secondary Leukemia After a Solid Tumor in Childhood According to the Dose of Epipodophyllotoxins and Anthracyclines: A Case-Control Study by the Société Française d’Oncologie Pédiatrique

PURPOSEnTo estimate the risk of secondary leukemia as a function of the dose of epipodophyllotoxins and anthracyclines.nnnMETHODSnWe conducted a case-control study of the risk of secondary leukemia or myelodysplasia after a solid tumor in childhood within the Société Française dOncologie Pédiatrique, including 61 patients with leukemia matched with 196 controls. The characteristics of the first cancer, the patients family history of cancer, and the treatment (type, cumulative dose of chemotherapy, schedule of etoposide administration, and radiation dose delivered to active bone marrow) were compared in the two groups.nnnRESULTSnOnly two factors were found to increase the risk of leukemia in multivariate analysis, namely, the type of the first tumor, with an excess risk in patients with Hodgkins disease (relative risk 6.4; 95% confidence interval [CI], 1.6 to 24) or osteosarcoma (relative risk 5; 95% CI, 1.3 to 19), and exposure to epipodophyllotoxins and anthracyclines. The risk of leukemia increased regularly with the cumulative dose of etoposide. In summary, patients who received between 1.2 and 6 g/m(2) of epipodophyllotoxins or more than 170 mg/m(2) of anthracyclines had a seven-fold higher risk (95% CI, 2.6 to 19) compared with patients who received lower doses or none of these drugs. The risk of leukemia in patients who received more than 6 g/m(2) of epipodophyllotoxins was multiplied by 197 (95% CI, 19 to 2,058). The risk of leukemia was not increased by exposure to alkylating agents or radiotherapy.nnnCONCLUSIONnBoth epipodophyllotoxins and anthracyclines increase the risk of secondary leukemia. The current challenge is to minimize the mutagenic effects of these drugs by diminishing cumulative doses without losing the therapeutic benefits.

A new translocation in Burkitt's tumor cells

SummaryA t(8;22)(q24;q11) translocation was found in blood, bone marrow, and ascites cells from a European Burkitts lymphoma. Cell surface markers were identified as monoclonal IgG. The relationship between these two unusual findings is questionable in this cytologically typical Burkitts lymphoma.

Abnormalities of the short arm of chromosome 12 in acute nonlymphocytic leukemia and dysmyelopoietic syndrome

Abnormalities of the short arm of chromosome #12 (12p) were found in 18 patients, 7 with previously untreated acute nonlymphocytic leukemia (ANLL) and 11 with dysmyelopoietic syndromes (MDS) or ANLL following treatment for another malignant disease. The chromosome #12 abnormality was a partial deletion in 15 patients and a translocation in 3. The 12p- was the sole chromosomal abnormality in seven patients (four with de novo ANLL) and was associated with other chromosome abnormalities in eight patients. Thus, partial monosomy for 12p was often associated with other chromosomal changes and was a secondary abnormality in some cases. The consequences of this hemizygosity for genes located at 12p are discussed with references to the possible expression of a potentially mutated recessive gene. The study of c-K-ras 2, normally located at 12p, must be done in such cases, as the association of secondary blood disorders and multiple chromosome abnormalities suggests a possible mutation of this c-oncogene on chromosome #12.

In Vivo Elimination of Acentric Double Minutes Containing Amplified MYCN from Neuroblastoma Tumor Cells Through the Formation of Micronuclei

Neuroblastoma, the most common solid extracranial neoplasm in children, shows an appreciable variability in clinical evolution. Amplification of the MYCN oncogene in this tumor is detected in 25 to 30% of cases and is associated with poor clinical outcome. In this study, quantitative polymerase chain reaction and fluorescence in situ hybridization were used to determine MYCN amplification status in 46 neuroblastoma tumors. MYCN amplification was detected in tumors from 11 patients. Fluorescence in situ hybridization revealed the presence of micronuclei containing amplified MYCN sequences in 8 of the 11 tumors. Micronuclei are indicative of spontaneous elimination or loss of amplified sequences by tumor cells. Because the elimination of amplified sequences can be enhanced in vitro by specific drugs such as hydroxyurea, our observations suggest a new therapeutic strategy specifically targeted to cells with amplified genes.

C-banding studies in various blood disorders

Abstract A C-banding pattern study has been performed on 70 patients having Philadelphia chromosome-positive chronic myeloid leukemia (CML), 35 with polycythemia vera, 21 with myeloid metaplasias, 40 with acute myeloblastic leukemia (AML) as well as on 70 controls. The length of the C blocks were classified into five levels by comparison with the short arm of chromosome 16, using Patil and Lubs proposals. A significant difference in the distribution of C-band levels of chromosome 1 and an excess of asymmetrical pairs were found for CML compared with the controls. An abnormal distribution of chromosome 9 C variants were also found in blood disorder patients compared with the controls. In CML patients a random distribution of C variants between 9q+ and 9 were found. For the chromosome 16 a significant difference was found concerning the intrapair asymmetry distribution in AML compared with controls.

MYCN gene overrepresentation detected in primary neuroblastoma tumour cells without amplification.

Neuroblastoma is the most frequent solid extracranial neoplasm of childhood, with a median age of presentation of under 2 years. This tumour is highly malignant in patients older than 12 months of age with metastatic disease. Clinical studies have confirmed that amplification of the MYCN proto‐oncogene is one of the best prognostic indicators of poor outcome. Approximately 30% of neuroblastoma tumours present MYCN amplification at diagnosis. Far less is known about the incidence and consequences of overrepresentation of the gene due to duplication or rearrangement of the chromosome arm in which the gene is situated. This study has analysed 110 neuroblastomas by FISH and has detected a gain of 1–3 copies per cell of MYCN in 8% of MYCN‐non‐amplified tumours. In these primary tumours, cells gained small numbers of additional MYCN genes by two mechanisms: formation of an isochromosome 2p, or an unbalanced translocation involving the short arm of chromosome 2 (with MYCN) and various partner chromosomes. Quantitative RT‐PCR showed three‐ to seven‐fold elevated MYCN expression in three tumours. Although the follow‐up time to date is still short, clinical outcome suggests that low‐level overexpression of the MYCN gene does not enhance tumour aggressiveness and rapidity of disease progression, as is often seen in neuroblastoma with MYCN amplification. It is hypothesized that the small elevation in MYCN expression could alter the regulation of apoptosis, as has been shown in experimental models. Copyright

Regional assignment of red cell acid phosphatase locus to band 2p25.

SummaryCytogenetic and enzyme studies of a child trisomic for 6p and monosomic for band 2p25 are reported. A tentative assignment of the ACP1 gene locus to band 2p25 is suggested by a 50% decrease in red cell acid phosphatase activity.

Two Burkitt's lymphomas with chromosome 6 long arm deletions

Two new European Burkitts lymphoma (BL) cases are reported. Their karyotypic abnormalities were unusual, without involvement of chromosomes #8, #14, #2, or #22. However, in both tumors, a 6q- chromosome was, present. These findings raise questions about the definition of BL and the involvement of various different DNA sequences in the mechanisms of BL genesis.

Two populations of double minute chromosomes harbor distinct amplicons, the MYC locus at 8q24.2 and a 0.43-Mb region at 14q24.1, in the SW613-S human carcinoma cell line

High-level amplifications observed in tumor cells are usually indicative of genes involved in oncogenesis. We report here a high resolution characterization of a new amplified region in the SW613-S carcinoma cell line. This cell line contains tumorigenic cells displaying high-level MYC amplification in the form of double minutes (DM+ cells) and non tumorigenic cells exhibiting low-level MYC amplification in the form of homogeneously staining regions (DM– cells). Both cell types were studied at genomic and functional levels. The DM+ cells display a second amplification, corresponding to the 14q24.1 region, in a distinct population of DMs. The 0.43-Mb amplified and overexpressed region contains the PLEK2, PIGH, ARG2, VTI1B, RDH11, and ZFYVE26 genes. Both amplicons were stably maintained upon in vitro and in vivo propagation. However, the 14q24.1 amplicon was not found in cells with high-level MYC amplification in the form of HSRs, either obtained after spontaneous integration of endogenous DM MYC copies or after transfection of DM– cells with a MYC gene expression vector. These HSR-bearing cells are highly tumorigenic. The 14q24.1 amplification may not play a role in malignancy per se but might contribute to maintaining the amplification in the form of DMs.

Intragenic breakpoints localized by array CGH in a t(2;6) familial translocation

A 244K genome-wide array based comparative genomic hybridization study was carried out in a familial translocation t(2;6)(p25;p21) balanced in the mother and unbalanced in her daughter. In the past, this translocation has allowed us to localize the HLA multigene cluster to chromosome 6. With microarray technology, confirmation of the chromosome localization of the HLA system was easily obtained, showing that such approach may be applied to the breakpoint localizations of other familial structural changes when they are unbalanced. The disruption of genes at the translocation breakpoints that did not have any phenotypic consequences in the parent will allow the generation of a map of ‘haplotolerant genes’. In addition, many genomic variants were detected with this technology, enlarging the possibility of analyzing their possible contribution to phenotypic diversity.