The doublecortin gene, a new molecular marker to detect minimal residual disease in neuroblastoma

Neuroblastoma (NB) is a pediatric cancer of highly variable clinical outcome. Much effort is devoted to detection of minimal residual (MRD) disease through RT-PCR or immunology of tissue-specific markers. Tyrosine hyrdroxylase (TH) has demonstrated a high utility to assess disease dissemination, although this marker can be lost due to clonal variability. Here we propose the use of the doublecortin (DCX) gene as a new molecular marker of neuroblastoma cells. DCX specifically appears in migrating neurons of the central and peripheral nervous system and interacts with and regulates the microtobule cytoskeleton. We have studied this gene by real-time quantitative RT-PCR in a total of 47 primary tumors and 202 samples of bone marrow or peripheral blood from 34 high-risk neuroblastoma patients as well as in 41 normal controls. The expression of DCX demonstrated a good specificity and concordance with TH, showing a higher expression rate in all the sample types studied as well as at different time points from diagnosis. We conclude that DCX would be a more efficient marker of minimal disease in neuroblastoma and perhaps other tumors of neuronal lineage.