In vitro investigations of mechanisms of action for the reversal of drug resistance in KB-8-5 and H460/Tax-R cell lines.

The overexpression of Pgp was inhibited in KB-8-5 cells but not H460/Tax-R cells after exposure to 5 μM 5FU (A). RT-PCR analysis showed Pgp mRNA levels to be consistent with protein levels (B). MTT assay demonstrated that low dose of 5FU (5 μM) reversed the resistance status of KB-8-5 cells to the treatment of Taxol (PTX) (C). However, no difference was observed in the H460/Tax-R cell line (D). Statistical analysis was performed using Student’s t-test (** p<0.01).