Mutant BRAF induces DNA strand breaks, activates DNA damage response pathway, and up-regulates glucose transporter-1 in nontransformed epithelial cells.
Mutant BRAF induces DNA strand breaks, activates DNA damage response pathway, and up-regulates glucose transporter-1 in nontransformed epithelial cells.
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突变体 BRAF 诱导 DNA 链断裂，激活 DNA 损伤反应途径，并上调非转化上皮细胞中的葡萄糖转运蛋白 1。
DOI：
10.1016/j.ajpath.2011.11.026
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Shih,Ie-Ming
中科院分区：
文献类型：
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作者：
Sheu,JimJinn-Chyuan;Guan,Bin;Tsai,Fuu-Jen;Hsiao,ErinYi-Ting;Chen,Chih-Mei;Seruca,Raquel;Wang,Tian-Li;Shih,Ie-Ming
尽管BRAF突变的致癌功能在人类癌症中已被明确证实，但它们在非转化上皮细胞中的作用仍不清楚。研究突变型BRAF在非转化上皮细胞中表达的细胞反应对于理解BRAF在癌症发病机制中的作用是至关重要的。在这项研究中，我们使用两个非转化cyst 108和RK 3E上皮细胞系作为模型，比较表达BRAFWT和BRAFV 600 E的细胞的表型。我们发现，转染BRAFV 600 E，而不是BRAFWT，表达载体抑制细胞增殖，并诱导两种细胞类型的凋亡。BRAFV 600 E产生活性氧，诱导DNA双链断裂，并引起随后的DNA损伤反应，表现为pCHK 2和γ H2 AX核灶数量增加以及pCHK 2、p53和p21的上调。因为BRAF 1和KRAS（别名Ki-ras）突变与编码葡萄糖转运蛋白1的GLUT 1上调相关，我们在此证明BRAFV 600 E的表达，而不是BRAFWT的表达，足以上调GLUT 1。总之，我们的研究结果为突变型BRAF诱导的致癌应激提供了新的见解，突变型BRAF诱导的致癌应激通过激活非转化细胞中的pCHK 2-p53-p21途径表现为DNA损伤和生长停滞，同时它也赋予肿瘤促进表型，如GLUT 1的上调，这有助于增强肿瘤细胞的葡萄糖代谢。
Although the oncogenic functions of activatingBRAFmutations have been clearly demonstrated in human cancer, their roles in nontransformed epithelial cells remain largely unclear. Investigating the cellular response to the expression of mutant BRAF in nontransformed epithelial cells is fundamental to the understanding of the roles of BRAF in cancer pathogenesis. In this study, we used two nontransformed cyst108 and RK3E epithelial cell lines as models in which to compare the phenotypes of cells expressing BRAFWTand BRAFV600E. We found that transfection of the BRAFV600E, but not the BRAFWT, expression vector suppressed cellular proliferation and induced apoptosis in both cell types. BRAFV600Egenerated reactive oxygen species, induced DNA double-strand breaks, and caused subsequent DNA damage response as evidenced by an increased number of pCHK2 and γH2AX nuclear foci as well as the up-regulation of pCHK2, p53, and p21. BecauseBRAFandKRAS(aliasKi-ras)mutations have been correlated withGLUT1up-regulation, which encodes glucose transporter-1, we demonstrated here that expression of BRAFV600E, but not BRAFWT, was sufficient to up-regulate GLUT1. Taken together, our findings provide new insights into mutant BRAF-induced oncogenic stress that is manifested by DNA damage and growth arrest by activating the pCHK2-p53-p21 pathway in nontransformed cells, while it also confers tumor-promoting phenotypes such as the up-regulation ofGLUT1that contributes to enhanced glucose metabolism that characterizes tumor cells.