Mechanisms of Chemically Induced Photosensitivity

我们已经证明，低剂量、非致死剂量的UVA暴露可诱导人HaCaT角质形成细胞的剂量依赖性细胞周期进展。我们发现UVA诱导了cyclin D1的积累，而cyclin D1的siRNA敲低阻断了UVA诱导的细胞周期进程，表明这一过程是由cyclin D1介导的。UVA辐照也能诱导AKT活化；用PI3K/AKT抑制剂孵育或显性负AKT感染细胞，细胞周期进展和增殖均受到抑制，提示AKT激活参与了uva诱导的细胞周期进展。相比之下，UVA暴露不会激活ERK；与ERK/MAPK抑制剂孵育对uva诱导的细胞周期进程没有影响。UVA暴露后观察到EGFR的活化。EGFR激酶抑制剂AG1478减弱了uva诱导的细胞周期进程，表明EGFR激活参与其中。此外，金属蛋白酶抑制剂GM6001阻断了uva诱导的细胞周期进程，而ADAM17的siRNA敲低具有类似的抑制作用，表明ADAM17在介导uva诱导的细胞周期进程中发挥作用。与ADAM17的作用一致，抗体阻断双侧调节蛋白减弱了uva诱导的细胞周期进程，暗示双侧调节蛋白参与其中。这些信号通路在uva诱导的细胞增殖中的识别将促进有效和安全的皮肤癌化学预防和治疗策略的发展。我们已经确定皮肤脂质胆固醇-5,7,9(11)-三烯-3 - β -醇（9- ddhc）可能是uva诱导的Smith-Lemli-Opitz综合征患者皮肤光敏的原因。9-DDHC在UVA照射下产生单线态氧和超氧化物，对角质形成细胞具有光毒性，在UVA敏感患者的血浆中发现浓度较高。我们已经证明，黄芪中的主要生物碱小檗碱对人类视网膜色素上皮细胞和晶状体细胞具有光毒性，而在St . Johns Wort中发现的金丝桃素对视网膜色素上皮细胞具有光毒性。我们已经成功地利用免疫自旋测定技术绘制了角化细胞中单线态氧的细胞内空间定位。最后，我们发现阻燃剂3,3,5,5-四溴双酚A （TBBPA）受到单线态分子氧的光敏氧化作用。TBBPA等阻燃剂的广泛使用会对环境造成危害，研究它们如何降解是很有意义的。

We have demonstrated that a low, non-lethal dose of UVA exposure induces dose-dependent cell cycle progression in human HaCaT keratinocytes. We found that UVA induced cyclin D1 accumulation, while siRNA knockdown of cyclin D1 blocked the UVA-induced cell cycle progression, indicating that this process is mediated by cyclin D1. UVA irradiation also induced AKT activation; when cells were incubated with PI3K/AKT inhibitor or infected with dominant negative AKT, cell cycle progression and proliferation were inhibited, suggesting that AKT activation is involved in UVA-induced cell cycle progression. In contrast, ERK was not activated by UVA exposure; incubation with ERK/MAPK inhibitor had no effect on UVA-induced cell cycle progression. Activation of EGFR was observed after UVA exposure. EGFR kinase inhibitor AG1478 attenuated UVA-induced cell cycle progression, indicating the involvement of EGFR activation. Furthermore, metalloprotease inhibitor GM6001 blocked UVA-induced cell cycle progression, and siRNA knockdown of ADAM17 had a similar inhibitory effect, demonstrating that ADAM17 has a role in mediating the UVA-induced cell cycle progression. Consistent with the role of ADAM17, antibody blocking amphiregulin attenuated UVA-induced cell cycle progression, implying the involvement of amphiregulin. Identification of these signaling pathways in UVA-induced cell proliferation will facilitate the development of efficient and safe chemopreventive and therapeutic strategies for skin cancer.We have identified the skin lipid cholesta-5,7,9(11)-trien-3 beta-ol (9-DDHC) as the putative agent responsible for UVA-induced skin photosensitivity in Smith-Lemli-Opitz syndrome patients. 9-DDHC generates singlet oxygen and superoxide upon UVA irradiation, is phototoxic to keratinocytes and is found in higher concentrations in plasma from UVA sensitive patients. We have demonstrated that berberine, the main alkaloid present in Goldenseal, is phototoxic to human retinal pigment epithelial cells and lens cells, while hypericin, found in St Johns Wort, is photototoxic to retinal pigment epithelial cells. We have successfully mapped the intracellular spatial localization of singlet oxygen in keratinocytes using the immuno-spin assay technique. Finally, We have found that the flame retardant 3,3,5,5-tetrabromobisphenol A (TBBPA) is subject to photosensitized oxidation involving singlet molecular oxygen. Wide use of flame retardants such as TBBPA can pose an environmental hazard and it is of interest to investigate how they may degrade.