Fig. 2

Pt suppressed UVA-induced α-MSH expression in HaCaT cells and other melanogenic proteins in B16F10 cells. (A) HaCaT cells were first treated with Pt (0–5 μM) or Rv (10 μM) for 24 h and then irradiated or not with 3 J/cm2 UVA. After 8 h, cells were collected, proteins were extracted. The Western blot method to determine POMC and α-MSH protein levels. (B–D) The conditioned medium obtained from Pt pretreated (2.5 or 5 μM, 24 h) and 3 J/cm2 UVA-irradiated HaCaT cells were tested on B16F10 cells for the indicated time points. The Western blot method determined the expression of CREB, p-CREB (2 h) (B), MITF (4 h) (C) or tyrosinase (24 h) proteins (D). β-actin or histone proteins were used as loading control proteins. AlphaEaseFC™ software was used to measure the immunoreactive protein bands (Genetic Technologies, Inc. Florida, USA). (E) Pt inhibited melanin formation in α-MSH-stimulated B16F10 cells – different concentrations of Pt (0–30 μM, 24 h) were first treated to B16F10 cells, and then stimulated or not with α-MSH (1 μM, 24 h). Melanin was quantified as described in the methodology. Results were denoted as mean ± SD of three or more independent experiments. Statistical significance was considered as ***p < 0.001 compared to untreated control and ###p < 0.001 compared to α-MSH-stimulated cells.