N-myc amplification and cell proliferation rate in human neuroblastoma

In neuroblastoma, N-myc amplification has been found to be strikingly associated with rapid tumour progression and poor prognosis. Recent studies have demonstrated that cell proliferative activity also significantly predicts the clinical outcome in patients with neuroblastoma. In order to define the correlation between N-myc amplification and cell proliferation rate, in the present investigation the two parameters were first assessed in 48 neuroblastoma tumours. N-myc amplification was evaluated in frozen specimens by Southern-blot analysis using the NB 19-21 probe and it was detected in nine patients. Cell proliferative activity was determined by measuring the AgNOR protein area in histological sections selectively stained by silver. The mean AgNOR protein area value of neuroblastomas with N-myc amplification (3.63 ± 1.62 μm²) was not significantly different from that of neuroblastomas without N-myc amplification (2.46 ± 1.57 μm²; P=0.30). On the other hand, both N-myc amplification and AgNOR protein expression were found to be significantly related to the clinical outcome of the disease (P