ErbB2 upregulates the Na+,HCO3 --cotransporter NBCn1/SLC4A7 in human breast cancer cells via Akt, ERK, Src, and Kruppel-like factor 4
ErbB2 upregulates the Na+,HCO3 --cotransporter NBCn1/SLC4A7 in human breast cancer cells via Akt, ERK, Src, and Kruppel-like factor 4
复制标题
DOI：
10.1096/fj.13-233288
复制
发表时间：
2014-01-01
期刊：
影响因子：
4.8
通讯作者：
Pedersen, Stine F.
中科院分区：
文献类型：
--
作者：
Gorbatenko, Andrej;Olesen, Christina W.;Pedersen, Stine F.
酸碱运输的失调在癌症的发展中起着核心作用。我们之前证明了截短的、组成型活性 ErbB2 (HER2) 受体 NErbB2 对 MCF-7 乳腺癌细胞中 Na+,HCO3- 协同转运蛋白 NBCn1 (SLC4A7) 的强烈上调，并表明患者乳腺癌组织中 NBCn1 的表达和活性增加。在这里，我们首次对 SLC4A7 启动子进行深入表征，并确定了其最小的 NErbB2 敏感区域。 PI3K、Akt1、ERK1/2 或 Src 的抑制或 siRNA 介导的敲低使表达 NErbB2 的 MCF-7 细胞中的 NBCn1 蛋白水平分别降低约 50%、60%、30% 和 35%。此外，转录因子 Kruppel 样因子 4 (KLF4) 的敲低使 NBCn1 蛋白表达减少约 40%，而 KLF4 过表达使 NBCn1 表达增加 50-80%。相反，敲低密切相关的转录因子特异性蛋白 1 (Sp1) 或转染显性失活 Sp1 可使 NBCn1 表达分别增加约 35% 和约 50%。刺激 SKBr3 细胞中的全长 ErbB1、-2 和 -3 受体（分别是 NRG1 或 EGF 的 1.5 倍和 2 倍）或在 MCF-7 细胞中进行外源表达后，NBCn1 表达也会增加。最后，NRG1 或 EGF 刺激使 SKBr3 细胞的酸排出能力增加了一倍以上。总之，ErbB 受体信号传导强烈上调 NBCn1，其方式涉及 KLF4 和 Sp1（在癌症发展中发挥核心作用的转录因子）的相反作用。 ErbB 诱导的 NBCn1 介导的酸挤出上调可能在乳腺上皮和其他具有高 ErbB 受体水平的组织中发挥重要的生理和病理生理作用。 Na+,HCO3--人乳腺癌细胞中通过 Akt、ERK、Src 和 Kruppel 样因子 4 的协同转运蛋白 NBCn1/SLC4A7。
Misregulation of acid-base transport plays central roles in cancer development. We previously demonstrated the strong up-regulation of the Na+,HCO3- cotransporter NBCn1 (SLC4A7) in MCF-7 breast cancer cells by a truncated, constitutively active ErbB2 (HER2) receptor, NErbB2, and showed that NBCn1 expression and activity are increased in breast cancer tissue from patients. Here, we present the first in-depth characterization of an SLC4A7 promoter and identify its minimal NErbB2-sensitive region. Inhibition or siRNA-mediated knockdown of PI3K, Akt1, ERK1/2, or Src decreased the NBCn1 protein level in NErbB2-expressing MCF-7 cells by approximate to 50, 60, 30 and 35%, respectively. Further, knockdown of the transcription factor Kruppel-like factor 4 (KLF4) reduced NBCn1 protein expression by approximate to 40%, and KLF4 overexpression increased NBCn1 expression by 50-80%. In contrast, knockdown of the closely related transcription factor specificity protein 1 (Sp1) or transfection with dominant-negative Sp1 increased NBCn1 expression by approximate to 35 and approximate to 50%, respectively. NBCn1 expression was also increased by stimulation of full-length ErbB1, -2, and -3 receptors in SKBr3 cells (1.5- and 2-fold by NRG1 or EGF, respectively) or after their exogenous expression in MCF-7 cells. Finally, stimulation with NRG1 or EGF more than doubled acid extrusion capacity in SKBr3 cells. In conclusion, NBCn1 is strongly upregulated by ErbB receptor signaling in a manner involving opposite effects of KLF4 and Sp1, transcription factors with central roles in cancer development. ErbB-induced up-regulation of NBCn1-mediated acid extrusion may play important physiological and pathophysiological roles in the breast epithelium and other tissues with high ErbB receptor levels.Gorbatenko, A., Olesen, C. W., MOrup, N., Thiel, G., Kallunki, T., Valen, E., Pedersen, S. F. ErbB2 upregulates the Na+,HCO3--cotransporter NBCn1/SLC4A7 in human breast cancer cells via Akt, ERK, Src, and Kruppel-like factor 4.