Use of an anti-ras ribozyme to alter the malignant phenotype of a human bladder cancer cell line.

PURPOSE

In this study, we evaluated the ability of a ribozyme (catalytic RNA), which site specifically cleaves the mRNA of the activated H-ras gene, to alter the malignant phenotype of an invasive human bladder cancer cell line.

MATERIALS AND METHODS

The human bladder cancer cell line EJ which contains the activated H-ras gene was used in these studies. Cell lines with and without the anti-ras ribozyme were examined for their malignant potential in athymic (nude) mice by using an orthotopic model of bladder cancer. Endpoints evaluated included tumor take and animal survival.

RESULTS

EJ tumors containing the anti-ras ribozyme showed a reduction in tumor take (35% versus 45%) and prolonged survival (74 days versus 65 days) compared with standard EJ cells. This survival advantage was not as pronounced as anticipated. To evaluate this finding, we examined the tumor from mice originally inoculated with the ribozyme-containing cell line to determine if the ribozyme was still present. Approximately 60% of the animals had lost ribozyme expression. Animals that maintained ribozyme expression had a mean survival of 81 +/- 4 days which was significantly prolonged compared with control mice (65 +/- 5 days).

CONCLUSION

This study suggests that the invasive phenotype is blunted with the anti-ras ribozyme, delaying but not abolishing the metastatic phenotype. These results further delineate the roles of ras genes in malignancy and demonstrate that ribozymes may be a powerful tool for exploring the role of individual oncogenes and may be used as anticancer agents.