Genes proximal and distal to MYCN are highly expressed in human neuroblastoma as visualized by comparative expressed sequence hybridization.

MYCN amplification is associated with poor prognosis in neuroblastoma disease. To improve our understanding of the influence of the MYCN amplicon and its corresponding expression, we investigated the 2p expression pattern of MYCN amplified (n = 13) and nonamplified (n = 4) cell lines and corresponding primary tumors (n = 3) using the comparative expressed sequence hybridization technique. All but one MYCN amplified cell line displayed overexpression at 2p. Expression peaks were observed frequently at 2pter and less frequently at 2p24 (MYCN locus), 2p23.3-23.2, and/or 2p23.1. Importantly, cell lines and two corresponding primary tumors displayed expression peaks at similar loci. No significant 2p24 expression level was observed for those cell lines displaying a low amplification rate (n = 3) by comparative genomic hybridization. Only the cell lines with an enhanced peak at 2p23.2-23.3 displayed coamplification of the ALK gene (2p23.2), reported to be associated with unfavorable prognosis. Finally, two of four cell lines without MYCN amplification, both derived from patients with poor outcome, also showed an expression peak at 2p23.2. These data indicate that, besides MYCN, other genes proximal and distal to MYCN are highly expressed in neuroblastoma. The prognostic significance of expression peaks at 2p23.2-23.3, independent of MYCN and ALK status, remains to be investigated.