Expression of apoptosis, cell proliferation, and drug resistance genes in pediatric Wilms' tumors.

The expression of genes associated with apoptosis, cell proliferation and drug resistance in tumor cells was investigated in two pediatric Wilms' tumor patients (MCH-WT-1 and MCH-WT-3) for their association with cell cycle, daunorubicin accumulation and clinical data. DNA content, cell cycle and drug accumulation were analyzed immediately after surgery by flow cytometry and mRNA expression by reverse transcriptase-polymerase chain reaction (RT-PCR) assay. Primary cell cultures were established from tumor specimens and tumor cells in both cases showed epithelial morphology. Although cell proliferation markers (Ki67 and PCNA) were expressed in both cases, MCH-WT-3 showed higher levels of mRNA expression, which corresponded, with metastatic behavior of the tumor in the patient. While p53 and p21 mRNAs were expressed at low levels in MCH-WT1, MCH-WT-3 showed high levels of p21 mRNA only. The increased expression of cyclin kinase inhibitor (p21) in MCH-WT-3 compared to MCH-WT-1 correlated with a higher percentage of G0/G1 cell population in the tumor specimen. Despite the expression of multidrug resistance markers (MDR1 and LRP) in MCH-WT-1, flow cytometric analysis showed tumor cell populations with very low and high daunorubicin accumulation and with the absence of any effect for verapamil and dipyridamole on daunorubicin accumulation of tumor cells.