AIM: To investigate small interfering RNA(si RNA)-mediated inhibition of nuclear factor-kappa B(NF-κB) activation and multidrug-resistant(MDR) phenotype formation in human Hep G2 cells. METHODS: Total RNA was extracted from human Hep G2 or LO2 cells. NF-κB/p65 m RNA was amplified by nested reverse transcription polymerase chain reaction and confirmed by sequencing. NF-κB/p65 was analyzed by immunohistochemistry. Specific-si RNA was transfected to Hep G2 cells to knock down NF-κB/p65 expression. The effects on cell proliferation, survival, and apoptosis were assessed, and the level of NF-κB/p65 or P-glycoprotein(P-gp) was quantitatively analyzed by enzyme-linked immunosorbent assay.RESULTS: Hep G2 cells express NF-κB/p65 and express relatively less phosphorylated p65(P-p65) and little P-gp. After treatment of Hep G2 cells with different doses of doxorubicin, the expression of NF-κB/p65, P-p65, and especially P-gp were dose-dependently upregulated. After Hep G2 cells were transfected with NF-κB/p65 si RNA(100 nmol/L), the expression of NF-κB/p65, P-p65, and P-gp were downregulatedsignificantly and dose-dependently. The viability of Hep G2 cells was decreased to 23% in the combination NF-κB/p65 si RNA(100 nmol/L) and doxorubicin(0.5 μmol/L) group and 47% in the doxorubicin(0.5 μmol/L) group(t = 7.043, P < 0.001). CONCLUSION: Knockdown of NF-κB/p65 with si RNA is an effective strategy for inhibiting Hep G2 cell growth by downregulating P-gp expression associated chemosensitization and apoptosis induction. AIM: To investigate small interfering RNA (si RNA) -mediated inhibition of nuclear factor-kappa B (NF-κB) activation and multidrug-resistant (MDR) phenotype formation in human Hep G2 cells. METHODS: Total RNA was extracted from human Hep NF-κB / p65 was amplified by nested reverse transcription polymerase chain reaction and confirmed by sequencing. NF-κB / p65 was analyzed by immunohistochemistry. Specific-si RNA was transfected to Hep G2 cells to knock down NF The effects on cell proliferation, survival, and apoptosis were assessed, and the level of NF-κB / p65 or P-glycoprotein (P-gp) was quantitatively analyzed by enzyme-linked immunosorbent assay .RESULTS: Hep After treatment of Hep G2 cells with different doses of doxorubicin, the expression of NF-κB / p65 and P-p65, P-p65, and especially P-gp were dose-dependently upregulated. After Hep G2 cells were transfec The expression of NF-κB / p65, P-p65, and P-gp were downregulated statistically and dose-dependently. The viability of Hep G2 cells was decreased to 23 % in the combination of NF-κB / p65 si RNA (100 nmol / L) and doxorubicin (0.5 μmol / L) group and 47% in the doxorubicin (0.5 μmol / L) : Knockdown of NF-κB / p65 with si RNA is an effective strategy for inhibiting Hep G2 cell growth by downregulating P-gp expression associated with chemosensitization and apoptosis induction.