Unexpected dose response of HaCaT to UVB irradiation
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Application of high-dosage UVB irradiation in phototherapeutic dermatological treatments present health concerns attributed to UV-exposure. In assessing UV-induced photobiological damage, we investigated dose-dependent effects of UVB irradiation on human keratinocyte cells (HaCaT). Our study implemented survival and apoptosis assays and revealed an unexpected dose response wherein higher UVB-dosage induced higher viability. Established inhibitors, such as AKT− (LY294002), PKC− (Gö6976, and Rottlerin), ERK− (PD98059), P38 MAPK− (SB203580), and JNK− (SP600125), were assessed to investigate UV-induced apoptotic pathways. Despite unobvious contributions of known signaling pathways in dose-response mediation, microarray analysis identified transcriptional expression of UVB-response genes related to the respiratory-chain. Observed correlation of ROS-production with UVB irradiation potentiated ROS as the underlying mechanism for observed dose responses. Inability of established pathways to explain such responses suggests the complex nature underlying UVB-phototherapy response.
KeywordsProliferation Apoptosis UVB, ultraviolet B Phototherapy ROS, reactive oxygen species
The work was supported by grants from the Ministry of Science and Technology, Taiwan (MOST 104-2112-M-007-016). C.S.C was supported by the Ministry of Science and Technology, Taiwan (MOST 105-2112-M-007-010).
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