The p73 gene is less involved in the development but involved in the progression of neuroblastoma

We performed expression, mutation, loss of heterozygosity (LOH) and fluores cence in situ hybridization (FISH) analyses of the p73 gene in neuroblastom as (NBs). Reverse transcription-polymerase chain reaction (RT-PCR) using pr imers which can detect both the p73 alpha and p73 beta transcripts was perf ormed on 30 fresh NBs and 22 NB cell lines. Aberrant expression of the p73 gene was found in 4 (25%) of 16 primary tumors found by mass screening and in 10 (71.4%) of 14 primary tumors found clinically. The rates of expressio n in these two types of tumors were significantly different (p=0.026, Fishe r's exact test). The incidence of aberrant expression of the p73 gene was s ignificantly higher in stage IV patients than in stages I, II, III plus IVS patients (p=0.0236, Fisher's exact test). No homozygous deletions or rearr angements of the p73 gene were found in any samples examined. In addition t o the polymorphism in exon 2, a silent mutation (codon 336 GCC/ GCT) was fo und in one primary tumor. LOH of the p73 gene was detected in 5 (15%) of 33 primary NBs using PCR-LOH analysis. FISH analysis showed that all 17 NB ce ll lines used in this study revealed allelic loss of the p73 gene, while mo st of them expressed the p73 gene. These results suggest that the p73 gene is not monoallelically expressed in NB. We conclude that the p73 gene is le ss involved in the development but involved in the progression of neuroblas toma.