OBJECTIVETo investigate the effect of small interfering RNA (siRNA)-mediated COX-2 gene silencing in enhancing the chemosensitivity of KB/VCR cell lines.

METHODSKB/VCR cells were trasnfected with COX-2 siRNA were examined for expressions of COX-2 and MDR-1 mRNAs with RT-PCR and for Rho-123 accumulation using flow cytometry. MTT assay was used to analyze the proliferation of the transfected KB/VCR cells.

RESULTSCompared with the negative and blank control groups, COX-2 siRNA transfection resulted in significant growth inhibition of KB/VCR cells exposed to vincristine (P<0.01), down-regulated the expressions of COX-2 and MDR-1 mRNAs, and obviously increased Rho-123 accumulation in KB/VCR cells.

CONCLUSIONCOX-2 gene silencing can enhance the chemosensitivity of KB/VCR cells to vincristine, the mechanism of which may involve down-regulated MDR-1 gene expression and inhibition of P-glycoprotein activity.

ATP Binding Cassette Transporter, Sub-Family B ; genetics ; metabolism ; Cyclooxygenase 2 ; genetics ; metabolism ; Drug Resistance, Neoplasm ; genetics ; Gene Expression Regulation, Neoplastic ; Gene Silencing ; Humans ; KB Cells ; RNA, Messenger ; RNA, Small Interfering ; Transfection ; Vincristine