Delayed and sustained activation of extracellular signal-regulated kinase in human keratinocytes by UVA - Implications in carcinogenesis
Delayed and sustained activation of extracellular signal-regulated kinase in human keratinocytes by UVA - Implications in carcinogenesis
复制标题
DOI：
10.1074/jbc.m405781200
复制
发表时间：
2004-12-17
影响因子：
4.8
通讯作者：
Chignell, CF
中科院分区：
文献类型：
--
作者：
He, YY;Huang, JL;Chignell, CF
暴露于太阳的紫外线辐射似乎是参与皮肤癌发展的最重要的环境因素。UVA是阳光中紫外线辐射的主要部分，被认为是人类致癌物质。在这项研究中，我们研究了延迟和持续激活ERK MAPK的UVA暴露。平行地，在UVA暴露后观察到具有类似时程的延迟Ras激活。被激活的Ras被发现定位于内膜，如高尔基体，而不是质膜。显性负性Ras（N17 Ras）的表达可阻断UVA对ERK的激活。表皮生长因子（EGF）受体（EGFR）激酶抑制剂AG 1478的存在对ERK或Ras活化没有影响，表明EGFR激酶活性不参与UVA对ERK的活化。相反，蛋白激酶C（PKC）消耗慢性12-O-十四烷酰佛波醇-13-乙酸酯治疗几乎取消UVA诱导的ERK和Ras激活。Ca 2+依赖性PKC抑制剂Go 6976的存在具有类似的效果。这些结果表明，ERK激活UVA介导的PKC在Ras依赖性途径。此外，通过流式细胞术检测到UVA暴露后细胞内钙水平逐渐增加。PLC抑制剂U 73122或钙螯合剂1，2-双（2-氨基苯氧基）乙烷-N，N，N ′，N ′-四乙酸四（乙酰氧基甲基酯）（BAPTA-AM）的存在阻断ERK和Ras活化，表明PLC和钙都是ERK活化所需的。我们的研究结果表明，与UVC和UVB不同，UVA诱导的延迟和持续ERK激活是EGFR激酶活性无关的，但PLC/钙/PKC介导的。延迟和持续的ERK激活为人HaCaT角质形成细胞提供了生存信号，这可能是UVA暴露引起的细胞转化和潜在皮肤致癌的重要机制。
Exposure to the sun's UV radiation appears to be the most important environmental factor involved in the development of skin cancer. UVA is the major portion of UV radiation in sunlight and is considered to be a human carcinogen. In this study, we have investigated the delayed and sustained activation of ERK MAPK by UVA exposure. In parallel, a delayed Ras activation with a similar time course was observed after UVA exposure. The activated Ras was found to be localized in endomembranes such as the Golgi apparatus instead of plasma membranes. Expression of dominant negative Ras (N17Ras) abolished ERK activation by UVA. The presence of AG1478, an epidermal growth factor (EGF) receptor ( EGFR) kinase inhibitor, had no effect on ERK or Ras activation, indicating that EGFR kinase activity is not involved in ERK activation by UVA. In contrast, protein kinase C (PKC) depletion by chronic 12-O-tetradecanoylphorbol-13-acetate treatment nearly abolished UVA-induced ERK and Ras activation. The presence of the Ca2+-dependent-PKC inhibitor Go6976 had a similar effect. These findings suggest that ERK activation by UVA is mediated by PKC in a Ras-dependent pathway. In addition, a gradual increase in intracellular calcium level after UVA exposure was detected by flow cytometry. The presence of the PLC inhibitor U73122 or the calcium chelator 1,2-bis(2-aminophenoxy)ethane-N, N, N',N'-tetraacetic acid tetrakis (acetoxymethyl ester) (BAPTA-AM) blocked both ERK and Ras activation, suggesting that both PLC and calcium are required for ERK activation. Our findings demonstrated that, different from UVC and UVB, UVA-induced delayed and sustained ERK activation is EGFR kinase activity-independent, but PLC/calcium/PKC-mediated. The delayed and sustained ERK activation provides a survival signal to human HaCaT keratinocytes, which may serve as an important mechanism for cell transformation and potential skin carcinogenesis in vivo caused by UVA exposure.