[Effect of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin on the expression of AhR and TGF-alpha]

To study HaCaT-keratinocyte cell lines, a chosen model of human epidermis in an attempt to analyze the mRNA expression of AhR and TGF-alpha induced by TCDD METHODS: Semi-quantitative reverse transcription PCR-technique was used for assaying the relative levels of AhR and TGF-alpha mRNA of HaCaT-cells during the proliferation period when the cells were cultured for 24 hours.

Relative level of the AhR-transcripts (corrected with beta-actin) decreased with the elevated concentration of TCDD and the relevant coefficient between the proliferation rate and concentration was -0.548, and the differences among all groups were significant (F =4.124, P =0.021). The vehicle control was respectively compared with 7 x 10(-10) mol/L (0.0620 +/- 0.0085) and 7 x 10(-9) mol/L (0.0518 +/- 0.0194) group, significantly different from the control group (0.1138 +/- 0.0227) (t = -3.48, P <0.05; t = -4.17, P <0.01), the expression amount being 55% and 45% of the control. Relative levels of TGF-alpha mRNA tended to increase with the elevated concentration with the significant coefficient of 0.695 (P < 0.01), and the differences among all groups were significant (F = 15.789, P =0.000). In two higher concentration group 7 x 10(-10) mol/L (0.1474 +/- 0.0390) and 7 x 10 (-9) mol/L (0.2133 +/- 0.0364), their relative expression amount of TGF-alpha mRNA was 2.6-fold, 3.8-fold of the control group (0.0561 +/- 0.0100) respectively. Further analysis for the relevant relationship between the amounts of the AhR mRNA and TGF- alpha mRNA showed a highly negative correlation, the coefficient being - 0.561 (P <0.05).

TCDD down-regulate the expression of AhR and up-regulate the expression of TGF-alpha. A strong negative correlation between AhR and TGF-alpha expression is found.