AIM:To establish a luciferase reporter cell line that respondsdioxin-like chemicals (DLCs) and on this basis to evaluateits characteristics and application in the determination ofDLCs.METHODS:A recombinant luciferase reporter plasmid wasconstructed by inserting dioxin-responsive element (DREs)and MMTV promoter segments into the pGL_3-promoterplasmid immediately upstream of the luciferase gene,whichwas structurally demonstrated by fragment mapping analysisin gel electrophoresis and transfected into the humanhepatoma cell line HepG_2,both transiently and stably,toidentify the inducible expression of luciferase by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).The time course,responsive period,sensitivity,structure-inducibility and dose-effect relationships of inducible luciferase expression to DLCswas dynamically observed in HepG_2 cells stably transfectedby the recombinant vector (HepG_2-Luc) and compared withthat assayed by ethoxyresorufin-O-deethylase (EROD) innon-transfected HepG_2 cells (HepG_2-wt).RESULTS:The inducible luciferase expression of HepG_2-Luc cells was noted in a time-,dose-,and AhR-dependentmanner,which peaked at 4 h and then decreased to a stablelevel at 14 h after TCDD treatment.The responsiveness ofHepG_2-Luc cells to TCDD induction was decreased withculture time and became undetectable at 10~(th) month ofHepG_2-Luc cell formation.The fact that luciferase activityinduced by 3,3’,4,4’-PCB in HepG_2-Luc cells was muchless than that induced by TCDD suggests a structure-inducibility relationship existing among DLCs.Within theconcentrations from 3.5×10~(-12) to 5×10~(-9) mol/L,significantcorrelations between TCDD doses and EROD activities wereobserved in both HepG_2-luc and HepG_2-wt cells.The correlationbetween TCDD doses from 1.1×10~(-13) to 1×10~(-8) mol/L andluciferase activities was also found to be significant in HepG_2-luc cells (r=0.997,P<0.001),but not in their HepG_2-wtcounterparts.For the comparison of the enzyme responsivenessbetween cell lines to TCDD,the luciferase sensitivity andreproducibility in HepG_2-luc cells were both better than thatof EROD in HepG_2-wt cells,the former was at 1.1×10~(-13) mol/L and 3.5×10~(-12) mol/L,and the coefficients of variation(CV) of the latter was 15-30% and 22-38%,respectively.CONCLUSION:The luciferase expression of HepG_2-luc cellsestablished in the present study could sensitively respondto the DLCs stimulation and might be a prospective tool forthe determination of DLCs. AIM: To establish a luciferase reporter cell line that respondsdioxin-like chemicals (DLCs) and on this basis to evaluate the characteristics and application in the determination of DLCs. METHODS: A recombinant luciferase reporter plasmid wasconstructed by inserting dioxin-responsive elements (DREs) and MMTV promoter segments into the pGL_3-promoterplasmid immediately upstream of the luciferase gene, whichwas structurally demonstrated by fragment mapping analysisin gel electrophoresis and transfected into the human hepatoma cell line HepG_2, both transiently and stably, toidentify the inducible expression of luciferase by 2,3,7, The time course, responsive period, sensitivity, structure-inducibility and dose-effect relationships of inducible luciferase expression to DLCswas predominantly observed in HepG_2 cells stably transfected by the recombinant vector (HepG_2-Luc) and compared withthat assayed by ethoxyresorufin-O-deethylase (EROD) innon-transfected HepG_2 cells (HepG_2-wt) .RESULTS: The inducible luciferase expression of HepG_2-Luc cells was noted in a time-, dose-, and AhR-dependentmanner, which peaked at 4 h and then decreased to a stable level at 14 h after TCDD treatment. The responsiveness ofHepG_2-Luc cells to TCDD induction was decreased with culture time and became undetectable at 10 ~ (th) month ofHepG_2-Luc cell formation.The fact that luciferase activityinduced by 3,3 ’, 4,4’-PCB in HepG_2-Luc cells was muchless than that induced by TCDD suggests a structure-inducibility relationship existing among DLCs.Within the concentrations from 3.5 × 10 ~ (-12) to 5 × 10 ~ (-9) mol / L, significantcorrelationsbetween TCDD doses and EROD activities wereobserved in both HepG_2-luc and HepG_2-wt cells. The correlation between TCDD doses from 1.1 × 10 ~ (-13) to 1 × 10 ~ (-8) mol / L and luciferase activities was also found to be significant in HepG_2-luc cells r = 0.997, P <0.001), but not in their HepG_2-wtcounterparts.For the comparison of the enzyme responsivenessbetween cells lines to TCDD, the luciferase sensitivity and reproducibility in HepG_2-luc cells were both better than that of EROD in HepG_2-wt cells, the former was at 1.1 × 10 ~ (-13) mol / L and 3.5 × 10 ~ (-12) mol / L, and the coefficients of variation (CV) of the latter was 15-30% and 22-38%, respectively. CONCLUSION: The luciferase expression of HepG_2-luc cell established in the present study could be sensitively respond to the DLCs stimulation and might be a prospective tool forthe determination of DLCs.