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842 Tranexamic acid inhibit melanogenesis via up-regulating the level of TGF-β1 secreted by keratinocytes

      Objective: To observe the effects of tranexamic acid on the expression and secretion of TGF-β1 in human keratinocyte cell line(HaCaT),and to further investigate the effects of tranexamic acid-induced HaCaT-secreted TGF-β1 on melanogenesis by transferring the HaCaT-conditioned medium to normal human melanocytes(NHEMs). Methods: HaCaT cells were cultured with tranexiamic acid of different concentration. RT-PCR and ELISA were used to detcect the mRNA and protein expression of TGF-β1. Then we transfer the tranexamic acid-treated HaCaT-conditioned medium to NHEMs. Then we transfect normal control siRNA and TGF-β1 siRNA in HaCaT cells to knockdown TGF-β1, and transfer HaCaT-conditioned medium to NHEMs. RT-PCR and Western blot were used to detect the mRNA and protein expression of melanogenic-related genes, such as MITF, TRP-1 and TYR; melanin contents and tyrosinase activity were measured by NaOH assay and L-dopa assay. Results: Tranexamic acid increased the mRNA and protein expression of TGF-β1 in HaCaT cells. The mRNA and protein expressions of MITF, TRP-1 and TYR, melanin contents and tyrosinase activity were significantly reduced in NHEMs co-cultured with the tranexamic acid-treated HaCaT-conditioned medium. Moreover, melanin contents, tyrosinase activity, and the mRNA and protein expressions of MITF, TRP-1 and TYR were recovered in NHEMs when NHEMs were co-cultured with CCN1-knockdown tranexamic acid-treated HaCaT-conditioned medium. Conclusion: Tranexamic acid-induced HaCaT-secreted TGF-β1 inhibits melanogenesis in NHEMs. Keywords: Tranexamic acid; HaCaT; NHEMs; TGF-β1; melanogenesis