From the Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260.
the Women's Cancer Research Center of the UPMC Hillman Cancer Center, Pittsburgh, Pennsylvania 15232, and.
J Biol Chem. 2018 Jan 26;293(4):1120-1137. doi: 10.1074/jbc.M117.814368. Epub 2017 Nov 20.
Triple-negative breast cancer (TNBC) comprises ∼20% of all breast cancers and is the most aggressive mammary cancer subtype. Devoid of the estrogen and progesterone receptors, along with the receptor tyrosine kinase ERB2 (HER2), that define most mammary cancers, there are no targeted therapies for patients with TNBC. This, combined with a high metastatic rate and a lower 5-year survival rate than for other breast cancer phenotypes, means there is significant unmet need for new therapeutic strategies. Herein, the anti-neoplastic effects of the electrophilic fatty acid nitroalkene derivative, 10-nitro-octadec-9-enoic acid (nitro-oleic acid, NO-OA), were investigated in multiple preclinical models of TNBC. NO-OA reduced TNBC cell growth and viability , attenuated TNFα-induced TNBC cell migration and invasion, and inhibited the tumor growth of MDA-MB-231 TNBC cell xenografts in the mammary fat pads of female nude mice. The up-regulation of these aggressive tumor cell growth, migration, and invasion phenotypes is mediated in part by the constitutive activation of pro-inflammatory nuclear factor κB (NF-κB) signaling in TNBC. NO-OA inhibited TNFα-induced NF-κB transcriptional activity in human TNBC cells and suppressed downstream NF-κB target gene expression, including the metastasis-related proteins intercellular adhesion molecule-1 and urokinase-type plasminogen activator. The mechanisms accounting for NF-κB signaling inhibition by NO-OA in TNBC cells were multifaceted, as NO-OA () inhibited the inhibitor of NF-κB subunit kinase β phosphorylation and downstream inhibitor of NF-κB degradation, () alkylated the NF-κB RelA protein to prevent DNA binding, and () promoted RelA polyubiquitination and proteasomal degradation. Comparisons with non-tumorigenic human breast epithelial MCF-10A and MCF7 cells revealed that NO-OA more selectively inhibited TNBC function. This was attributed to more facile mechanisms for maintaining redox homeostasis in normal breast epithelium, including a more favorable thiol/disulfide balance, greater extents of multidrug resistance protein-1 (MRP1) expression, and greater MRP1-mediated efflux of NO-OA-glutathione conjugates. These observations reveal that electrophilic fatty acid nitroalkenes react with more alkylation-sensitive targets in TNBC cells to inhibit growth and viability.
三阴性乳腺癌（TNBC）约占所有乳腺癌的 20%，是最具侵袭性的乳腺癌症亚型。由于缺乏定义大多数乳腺肿瘤的雌激素和孕激素受体，以及受体酪氨酸激酶 ERB2（HER2），因此针对 TNBC 患者没有靶向治疗方法。这与转移性率高以及比其他乳腺癌表型的 5 年生存率低相结合，意味着需要新的治疗策略来满足巨大的未满足需求。本文研究了亲电脂肪酸硝烯衍生物 10-硝基-十八-9-烯酸（硝基油酸，NO-OA）在多种 TNBC 临床前模型中的抗肿瘤作用。NO-OA 降低了 TNBC 细胞的生长和活力，减弱了 TNFα 诱导的 TNBC 细胞迁移和侵袭，并抑制了 MDA-MB-231 TNBC 细胞在雌性裸鼠乳腺脂肪垫中的异种移植肿瘤生长。这些侵袭性肿瘤细胞生长、迁移和侵袭表型的上调部分是由 TNBC 中固有激活的促炎核因子κB（NF-κB）信号转导介导的。NO-OA 抑制了 TNFα 诱导的人 TNBC 细胞中 NF-κB 转录活性，并抑制了下游 NF-κB 靶基因表达，包括细胞间黏附分子-1 和尿激酶型纤溶酶原激活物等转移相关蛋白。NO-OA 抑制 TNBC 细胞中 NF-κB 信号转导的机制是多方面的，因为 NO-OA () 抑制了 NF-κB 亚基激酶β磷酸化和 NF-κB 降解抑制剂的磷酸化， () 烷基化 NF-κB RelA 蛋白以阻止 DNA 结合，和 () 促进 RelA 多泛素化和蛋白酶体降解。与非致瘤性人乳腺上皮 MCF-10A 和 MCF7 细胞的比较表明，NO-OA 更选择性地抑制了 TNBC 的功能。这归因于正常乳腺上皮中维持氧化还原平衡的机制更为简单，包括更有利的巯基/二硫键平衡、多药耐药蛋白 1（MRP1）表达程度更大以及更大程度的 MRP1 介导的 NO-OA-谷胱甘肽轭合物外排。这些观察结果表明，亲电脂肪酸硝烯与 TNBC 细胞中更易发生烷基化的靶标反应，从而抑制生长和活力。
