Augmentation of tissue transglutaminase expression and activation by epidermal growth factor inhibit doxorubicin-induced apoptosis in human breast cancer cells
Augmentation of tissue transglutaminase expression and activation by epidermal growth factor inhibit doxorubicin-induced apoptosis in human breast cancer cells
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DOI：
10.1074/jbc.m404976200
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发表时间：
2004-10-01
影响因子：
4.8
通讯作者：
Cerione, RA
中科院分区：
文献类型：
--
作者：
Antonyak, MA;Miller, AM;Cerione, RA
组织转氨酶（TGase）具有GTP结合/水解能力和酶转酰胺活性。TGase表达和活化的增加通常响应于促进细胞分化和凋亡的刺激而发生，但是这些刺激用于调节TGase表达和活化的信号传导机制以及TGase在这些细胞过程中的作用还不清楚。维甲酸（RA）持续诱导TGase的表达和活化，并且最近显示RA诱导的TGase表达在与表皮生长因子（EGF）共刺激的NIH 3 T3小鼠成纤维细胞中被抑制。在这里，我们调查是否EGF也拮抗RA诱导的TGase在乳腺癌细胞中的表达。我们发现EGF刺激对这些癌细胞中TGase表达和活化的影响非常不同。EGF不仅不能阻断RA诱导的TGase表达，而且单独的EGF足以有效地上调SKBR 3细胞以及MDAMB 468和BT-20细胞中的TGase表达和活化。抑制磷脂酰肌醇3-激酶活性严重削弱了EGF和RA增加TGase蛋白水平的能力，而组成型活性形式的磷脂酰肌醇3-激酶增强了SKBR 3细胞中EGF对TGase表达的诱导。由于EGF是一种公认的抗凋亡因子，我们研究了EGF提供的保护是否依赖于其上调SKBR 3和BT-20细胞中TGase活性的能力。将细胞暴露于TGase抑制剂或表达显性阴性形式的TGase可有效抑制EGF介导的保护作用，使其免受阿霉素诱导的细胞凋亡的影响。此外，外源性TGase在SKBR 3细胞中的表达模拟了EGF的生存优势，这表明TGase激活对于EGF的抗凋亡特性是必要的和足够的。这些发现首次表明EGF可以诱导人乳腺癌细胞中TGase的表达和激活，并且这通过促进化疗抗性而有助于其致癌潜力。
Tissue transglutaminase ( TGase) exhibits both a GTP binding/hydrolytic capability and an enzymatic transamidation activity. Increases in TGase expression and activation often occur in response to stimuli that promote cellular differentiation and apoptosis, yet the signaling mechanisms used by these stimuli to regulate TGase expression and activation and the role of TGase in these cellular processes are not well understood. Retinoic acid ( RA) consistently induces TGase expression and activation, and it was shown recently that RA-induced TGase expression was inhibited in NIH3T3 mouse fibroblasts co-stimulated with epidermal growth factor (EGF). Here we investigate whether EGF also antagonized RA-induced TGase expression in breast cancer cells. We found that EGF stimulation affected TGase expression and activation very differently in these cancer cells. Not only did EGF fail to block RA-induced TGase expression, but also EGF alone was sufficient to potently up-regulate TGase expression and activation in SKBR3 cells, as well as MDAMB468 and BT-20 cells. Inhibiting phosphoinositide 3-kinase activity severely diminished the ability of EGF and RA to increase TGase protein levels, whereas a constitutively active form of phosphoinositide 3-kinase potentiated the induction of TGase expression by EGF in SKBR3 cells. Because EGF is an established antiapoptotic factor, we examined whether the protection afforded by EGF was dependent on its ability to up-regulate TGase activity in SKBR3 and BT-20 cells. Exposure of cells to a TGase inhibitor or expression of a dominant-negative form of TGase potently inhibited EGF-mediated protection from doxorubicin-induced apoptosis. Moreover, expression of exogenous TGase in SKBR3 cells mimicked the survival advantage of EGF, suggesting that TGase activation is necessary and sufficient for the antiapoptotic properties of EGF. These findings indicate for the first time that EGF can induce TGase expression and activation in human breast cancer cells and that this contributes to their oncogenic potential by promoting chemoresistance.