Expression of the multidrug transporter, P-glycoprotein, in acute leukemia cells and correlation to clinical drug resistance

JNK signal transduction pathway regulates MDR1/P-glycoprotein-mediated multidrug resistance in colon carcinoma cells

AIM: To investigate the relationship between the JNK (c-Jun NH₂-terminal kinase) signal transduction pathway and multidrug resistance 1 (MDR1)/P-glycoprotein (P-gp)-mediated multidrug resistance of human colon carcinoma HCT8/V cells.

METHODS: The sensitivity of multidrug-resistant HCT8/V cells and drug-sensitive HCT8 cells to a variety of antitumor drugs was evaluated by MTT assay. After inhibition of the activation of the JNK signaling pathway, MDR1 promoter transcriptional activity and expression of MDR1 mRNA and P-gp were evaluated by luciferase activity assay, real-time fluorescence quantitative PCR (RFQ-PCR) and Western blot, respectively.

RESULTS: HCT8/V cells exhibited 10.49-fold higher resistance to vincristine than their parental counterparts. The IC₅₀ value of SP600125 (20 μmol/L) decreased from 191.08 mg/L ± 18.18 mg/L to 50.34 mg/L ± 15.71 mg/L and resistance index (RI) reached 3.80 (P < 0.01). After inhibition of the activation of the JNK signaling pathway with a JNK specific inhibitor, MDR1 promoter transcriptional activity showed a 2.55-fold decrease (0.03647 ± 0.00191 vs 0.01362 ± 0.00196, P < 0.01) and the expression of MDR1/P-gp was significantly down-regulated (0.34275 ± 0.0339 vs 0.13625 ± 0.0196, 0.88132 ± 0.1026 vs 0.56174 ± 0.1014, both P < 0.01) in HCT8/V cells.

CONCLUSION: The JNK signal transduction pathway regulates MDR1/P-glycoprotein-mediated multidrug resistance of HCT8/V cells possibly by up-regulating MDR1/P-gp expression.