No evidence for induction of key components of the Notch signaling pathway (Notch-1, Jagged-1) by treatment with UV-B, 1,25(OH)₂D₃, and/or epigenetic drugs (TSA, 5-Aza) in human keratinocytes in vitro

Figures & data

Figure 1. Treatment with 1,25(OH)₂D₃ protects human keratinocytes in part against the antiproliferative effects of UV-B-radiation. As shown here for HaCaT keratinocytes, treatment with 1,25(OH)₂D₃ protects human keratinocytes after 24, 48 and 72 h in part against the antiproliferative effects of UV-B-radiation. Proliferation was measured using a dye (CV)-based assay as described in Materials and Methods. Please note that 24 h following treatment with UV-B and 1,25(OH)₂D₃, 1,25(OH)₂D₃-mediated effects are more pronounced in cells treated with 100 J UV-B as compared with those treated with 500 J UV-B. Please also note that epigenetic drugs TSA and 5-Aza as well modulate the proliferation of HaCaT keratinocytes treated with and without UV-B.

Figure 2. Treatment with UV-B, 1,25(OH)₂D₃ and epigenetic drugs, alone or in combination, does not exert strong effects on protein expression of Notch-1 in non-malignant and in malignant human keratinocytes. Western analysis revealed that Notch-1 protein is expressed in cultured non-malignant (HaCaT keratinocytes) and malignant (SCL-1 cells) human keratinocytes. Results of representative experiments in HaCaT keratinocytes 48 h after UV-B irradiation are shown here. Please note that treatment with UV-B [(A) 0 J; (B) 100 J; (C) 500 J] and/or 1,25(OH)₂D₃ (10⁻⁸ M) does not exert strong effects on protein expression of Notch-1 after 24, 48 or 72 h. Please also note that treatment with epigenetic modulating drugs (TSA, 5-Aza) does not exert strong effects, alone or in combination with UV-B and/or 1,25(OH)₂D₃, on protein expression of Notch-1 in HaCaT keratinocytes. Western analysis of GAPDH protein (lower band) served as control.

Figure 3. Treatment with UV-B, 1,25(OH)₂D₃ and epigenetic drugs, alone or in combination, does not exert strong effects on protein expression of Jagged-1 in non-malignant and in malignant human keratinocytes. Western analysis revealed that Jagged 1 protein is expressed in cultured non-malignant (HaCaT keratinocytes) and malignant (SCL-1 cells) human keratinocytes. Results of representative experiments in HaCaT keratinocytes 48 h after UV-B irradiation are shown here. Please note that treatment with UV-B [(A) 0 J; (B) 100 J; (C) 500 J] and/or 1,25(OH)₂D₃ (10⁻⁸ M) does not exert strong effects on protein expression of Jagged 1 after 24, 48 or 72 h. Please also note that treatment with epigenetic modulating drugs (TSA, 5-Aza) does not exert pronounced effects, alone or in combination with UV-B and/or 1,25(OH)₂D₃, on protein expression of Jagged 1 in HaCaT keratinocytes. Western analysis of GAPDH protein (lower band) served as control.