Modulation of uridine phosphorylase gene expression by tumor necrosis factor-α enhances the antiproliferative activity of the capecitabine intermediate 5′-deoxy-5-fluorouridine in breast cancer cells
Modulation of uridine phosphorylase gene expression by tumor necrosis factor-α enhances the antiproliferative activity of the capecitabine intermediate 5′-deoxy-5-fluorouridine in breast cancer cells
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DOI：
10.1124/mol.105.018515
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发表时间：
2006-04-01
影响因子：
3.6
通讯作者：
Pizzorno, G
中科院分区：
文献类型：
--
作者：
Wan, LX;Cao, DL;Pizzorno, G
尿苷磷酸化酶（UPase）已被证明在5-氟尿嘧啶（5- fu）的抗肿瘤活性和其口服前药卡培他滨的合成代谢中发挥重要作用，通过将5'-脱氧-5-氟吡啶（5'-DFUR）转化为5- fu。本研究探讨了肿瘤坏死因子- α (tumor necrosis factor- α, tnf - α)对UPase基因表达和5′-DFUR抗增殖活性的影响，并阐明了其信号转导途径。我们的数据表明，tnf - α显著诱导EMT6小鼠乳腺癌细胞中UPase mRNA的表达及其酶活性，导致5'-DFUR的细胞毒性增强。这进一步证实了5'- dfur来源的5- fu核苷酸进入核酸的增加。为了阐明tnf - α诱导UPase表达的机制，我们首先通过一系列5'缺失启动子-荧光素酶构建体观察了tnf - α对UPase启动子活性的影响。瞬时转染分析显示，EMT6细胞中tnf - α诱导模式与UPase启动子区域存在核因子- κ B （nf - κ B）结合元件（-1332/-1312 bp）一致。此外，电泳迁移率转移实验、超转移实验和共转染实验显示，p65的激活是tnf - α诱导UPase的原因。最后，tnf - α诱导的UPase可以被nf - κ B抑制剂PS-341抑制。综上所述，tnf - α通过NF-kappa B亚基p65依赖途径有效诱导UPase基因表达，增强细胞对5'-DFUR的敏感性。阐明这一调控机制可能有助于临床应用以5- fu为基础的化疗。
Uridine phosphorylase (UPase) has been shown to play an important role in the antineoplastic activity of 5-fluorouracil (5-FU) and in the anabolism of its oral prodrug, capecitabine, through the conversion of 5'-deoxy-5-fluorouridine (5'-DFUR) into 5-FU. In this study, we investigated the effect of tumor necrosis factor-alpha (TNF-alpha) on UPase gene expression and 5'-DFUR antiproliferative activity and elucidated the involved signal transduction pathway. Our data indicate that TNF-alpha significantly induced UPase mRNA expression and its enzymatic activity in EMT6 murine breast cancer cells, leading to an enhanced cytotoxicity of 5'-DFUR. This is further confirmed by an increased incorporation of 5'-DFUR-originated 5-FU nucleotides into nucleic acids. To clarify the mechanism of TNF-alpha-induced UPase expression, we first observed the effect of TNF-alpha on the UPase promoter activity with a series of 5'-deleted promoter-luciferase constructs. Transient transfection analysis showed that the TNF-alpha-inductive pattern in EMT6 cells was consistent with the presence of a nuclear factor-kappa B (NF-kappa B) binding element (-1332/-1312 bp) in the UPase promoter region. Furthermore, electrophoretic mobility shift assays, supershift, and cotransfection assays revealed that the activation of p65 was responsible for UPase induction by TNF-alpha. Finally, the induction of UPase by TNF-alpha could be suppressed by PS-341, a NF-kappa B inhibitor. In summary, TNF-alpha efficiently induces UPase gene expression through a NF-kappa B subunit p65-dependent pathway enhancing cell sensitivity to 5'-DFUR. The elucidation of this regulation mechanism may aid in the clinical use of 5-FU-based chemotherapy.