Objective       To determine the effect of silencing pregnane X receptor (PXR) expression by RNA interference on the chemosensitivity of LS174T cells to oxaliplatin.       Methods      The PXR RNAi expression plasmids were constructed

and then transfected LS174T cells to establish stable transfection cell clones. The expression of specificity protein (SP) 1 and multidrug resistance-associate protein 3 (MRP3) were detected by RT-PCR and Western blotting. The chemosensitivity of the transfected and nontransfected cells to oxaliplatin was ev

aluated by MTT assay.       Results      The cell clones PXRi 1# and PXRi 2# with stable PXR silence were constructed successfully. In cell clones PXRi 1# and PXRi 2#

the expression of MRP3 at mRNA and protein levels was decreased markedly

and that of SP1 also was decreased. Compared with control group

the IC

50

of PXRi 1# and PXRi 2# cells to oxaliplatin was significantly decreased (4.83±0.22 and 4.75±0.19 vs 9.44±0.37

P0.05).       Conclusion       Interference of PXR expression can elevate the chemosensitivity of LS174T cells to oxaliplatin

which might be through PXR knock-down downregulating SP1 and MRP3.