Molecular cytogenetic characterization of two non-MYCN amplified neuroblastoma cell lines with complex t(11;17).

The pediatric tumor neuroblastoma is characterized by a very variable, and at times unpredictable, pattern of clinical behavior, ranging from a benign localized tumor to an aggressive malignancy with poor prognosis. Standard clinical and pathological assessments do not always differentiate reliably between tumor subtypes and, therefore, genetic markers are now playing an increasingly important role in treatment decisions. MYCN oncogene amplification, for example, provides a useful marker of poor prognosis. However, less than one-half of all patients who present with, or who later develop, metastatic disease show MYCN amplification. Consequently, the identification of characteristic patterns of genetic alteration in the remaining tumors is of importance. In this report, we describe two new cell lines that we have established from metastatic, non-MYCN amplified, advanced stage neuroblastomas. These cell lines show a number of features in common, including unbalanced translocation between 11q and 17q, loss of 3p, 4p and 11q and gain of 17q. Therefore, they provide a valuable resource for the characterization of genetic pathways leading to aggressive tumor growth in non-MYCN amplified neuroblastomas.

Cytogenetically cryptic AML1-ETO and CBF beta-MYH11 gene rearrangements: incidence in 412 cases of acute myeloid leukaemia.

The rearrangements t(8;21)(q22;22) and inv(16)(p13q22) are two of the most frequently seen in acute myeloid leukaemia (AML), accounting for 8% and 4% of cases respectively. Detection of these abnormalities is important for disease management as both are associated with good responses to conventional chemotherapy and prolonged disease-free survival. Recent reports using reverse transcriptase polymerase chain reaction (RT-PCR) suggest that significant proportions of AML cases without a visible t(8;21) or inv(16) show expression of an abnormal fusion gene transcript and, consequently, they could not be detected using conventional cytogenetic analysis alone. We present here a four centre study involving 412 cases of AML screened using both standard cytogenetics and RT-PCR for AML1-ETO and CBF beta-MYH11. We detected a cytogenetic t(8;21) in 31 out of 412 (7.5%) cases and an inv(16) or t(16;16) variant in 27 out of 412 (6.6%) cases. RT-PCR detected only two cases (0.5%) of cryptic t(8;21) and no instances of cryptic inv(16). Both cryptic t(8;21) cases had the classic M2 FAB morphology for this type of disease. Our data concur with the established FAB type distribution of the rearrangements and indicate that cryptic t(8;21) and inv(16) may be much less frequent than reported elsewhere.