The purpose of this study is to evaluate the correlations between the multidrug resistance-associated protein (MRP) and multidrug resistance (MDR1) gene in osteosarcoma, and their prognostic significances by RT-PCR method.

We isolated RNA from 34 fresh deep-frozen primary osteosarcoma tissue specimens and evaluated the expression level of MRP and MDR1 m-RNA using RT-PCR method. GAPDH was used as the housekeeping gene for the experiment.

The average MRP/GAPDH m-RNA ratio was 0.550 and the average MDR1/GAPDH m-RNA ratio was 0.419. There were moderate degree of correlations between MRP/GAPDH m-RNA and MDR1/GAPDH m-RNA ratio (p<0.05). There was significant correlations between the chemotherapy response and the MDR1/GAPDH m-RNA ratio (p<0.05), but not with the MRP/GAPDH ratio. Multivariate analysis for the correlation between the MRP and MDR1 gene expression and the chemotherapy response revealed that only the MDR1/GAPDH m-RNA ratio was significantly related to it (p<0.05).

There was a moderate degree of correlation between the expressions of MRP and MDR1 genes. However, the chemotherapy response showed significant correlations with the expression of MDR1 gene, but not with MRP gene.