Detection of neuroblastoma cells in blood by reverse transcriptase-polymerase chain reaction

To determine whether circulating tumor cells are present in patients with localized or disseminated neuroblastoma (NB).

Sixteen pediatric malignant tumor cell lines, including 10 NB, 4 primitive neuroectodermal tumor (PENT), 2 Wilms' tumor and 39 samples (tumor tissue, bone marrow and peripheral blood) from 8 patients with NB, were evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR) using two markers: neuroendocrine protein gene products 9.5 (PGP 9.5) and tyrosine hydroxylase (TH).

Analysis of RT-PCR products by agarose electrophoresis demonstrated that in culture cell lines the specificity for NB was highest in TH (9/10 with NB, 3/4 with PNET, 0/2 with Wilms' tumor) and the sensitivity was highest in PGP 9.5 10(-7). PGP 9.5 and TH mRNA were undetectable in the peripheral blood mononuclear cells (PBMNC) from normal children. Expression of these markers in 8 patients with NB at diagnosis and during treatment was found positive in 5 out of 8, all had been proved paralleling with their disease status. Two of the 5 became negative after further treatment.

These systems allow the detection of circulating NB cells with higher sensitivity and specificity. When RT-PCR is clinically used for the detection of NB cells in blood, that both PGP 9.5 and TH should be selected is recommended. The assessment of bone marrow alone might not be used as a single index of tumor dissemination.