Background. Neuroblastoma is the most common extracranial solid tumor in children. Tumor cells commonly express tyrosine hydroxylase (TH), the first enzyme of the cathecolamine byosinthesis. TH expression has been frequently found in peripheral blood and bone marrow of patients with advanced-stage neuroblastoma. Since TH expression not always correlates with clinical behaviour, we decided to quantify the amount of residual disease in a group of neuroblastoma patients. Objective. To evaluate the usefulness of the RT-Nested-PCR technique in the study of minimal residual disease in neuroblastoma. Methods. We used a nested-RT-PCR assay for TH with serial dilutions, in five patients with advanced neuroblastoma. Patients were monitored at diagnosis, during treatment, and at regular intervals after completion of therapy. Twenty samples of peripheral blood and 13 bone marrow samples were analyzed. We used peripheral blood from 30 healthy donors as negative control, and the IMR-32 cell line as positive control. The sensitivity of the assay was stablished in the detection of 1 tumor cell in 107 normal cells. Results. TH gene expression was found in 65% of peripheral blood and in 46% of bone marrow from neuroblastoma patients. We also found TH expression in 33% of the samples of peripheral blood from healthy donors. The specificity of PCR products was determined by sequentation. In four out of five patient studied, we found a relative increase in the degree of residual disease over the period analyzed. Two of them presented a clinical relapse, and two remain disease-free. The other patient who presented stable levels of residual disease is disease-free. Conclusions. The quantification of residual disease in neuroblastoma by the analysis of TH expression allows to differentiate patients with minimal residual disease whose levels of expression change over the time. The detection of TH expression in the peripheral blood of healthy donors suggest the presence of illegitimate expression.
|Translated title of the contribution||Monitoring of minimal residual disease in neuroblastoma by a RT-PCR assay with serial dilutions|
|Number of pages||5|
|Publication status||Published - 2001|