Flow cytometric and molecular analysis of proliferative activity and DNA content in neuroblastoma: presence of stationary cells in S-phase.

Twenty-nine previously untreated neuroblastomas were analyzed for DNA content and percentage of cells in S-phase, both determined by flow cytometry, and N-myc oncogene copy number. Twelve of them were also tested for histone H3 transcript levels as a marker of actual proliferative activity. A significantly higher S-phase fraction was associated with advanced stages of disease, unfavorable (i.e., near-diploid and near-tetraploid) DNA content, and N-myc amplification. The occurrence of six tumors with a remarkable (greater than or equal to 10%) S-phase fraction but lacking histone H3 transcripts suggests the presence of stationary S-phase cells in neuroblastoma.