Abstract: Objective To investigate the effect of acitretin and narrow-band UVB(NB-UVB) on the cell proliferation and mRNA expression of heparin-binding epidermal growth factor like growth factor (HB-EGF) of cultured normal human keratinocytes.Methods Keratinocytes were isolated from the foreskin of young adults,and subjected to primary culture.After 3-5 passages,the keratinocytes were cultured with 1μmol/L acitretin for 12 h and/or irradiated with 100 mJ/cm² NB-UVB.The proliferation potency of cells was detected by MTT colorimetric assay,and mRNA expression of HB-EGF by reverse transcription polymerase chain reaction(RT-PCR) and real-time quantitative RT-PCR.Results The treatment with acitretin and/or NB-UVB inhibited the keratinocyte growth and upregulated the mRNA expression of HB-EGF.The keratinocyte proliferation was inhibited by 14.4%,8.7% and 19.7%,and the mRNA expression of HB-EGF was elevated by 7.1,2.5 and 8.6 folds,respectively by 1μmol/L acitretin,100 mJ/cm² NB-UVB and the combination of them.Conclusions Acitretin and NB-UVB could synergistically upregulate the expression of HB-EGF,which may be involved in the modulation of the inhibitory effect on the proliferation of keratinocytes.

Key words: Growth substances, Keratinocytes, Retinoids, Ultraviolet rays