Metastasizing cancer cells encounter a multitude of stresses throughout the metastatic cascade. Oxidative stress is known to be a major barrier for metastatic colonization, such that metastasizing cancer cells must rewire their metabolic pathways to increase their antioxidant capacity. NADPH is essential for regeneration of cellular antioxidants and several NADPH-regenerating pathways have been shown to play a role in metastasis. We have found that metastatic melanoma cells have increased levels of both NADPH and NADP+ suggesting increased de novo biosynthesis of NADP+. De novo biosynthesis of NADP+ occurs through a single enzymatic reaction catalyzed by NAD+ kinase (NADK). Here we show that different NADK isoforms are differentially expressed in metastatic melanoma cells, with Isoform 3 being specifically upregulated in metastasis. We find that Isoform 3 is more potent in expanding the NADP(H) pools, increasing oxidative stress resistance and promoting metastatic colonization compared to Isoform 1. We have found that Isoform 3 is transcriptionally upregulated by oxidative stress through the action of NRF2. Together, our work presents a previously uncharacterized role of NADK isoforms in oxidative stress resistance and metastasis and suggests that NADK Isoform 3 is a potential therapeutic target in metastatic disease.

中文翻译：

---

NAD + 激酶的转录亚型调节氧化应激抵抗和黑色素瘤转移


转移癌细胞在整个转移级联反应中会遇到多种压力。众所周知，氧化应激是转移性定植的主要障碍，因此转移癌细胞必须重新连接其代谢途径以增加其抗氧化能力。NADPH 对于细胞抗氧化剂的再生至关重要，几种 NADPH 再生途径已被证明在转移中发挥作用。我们发现转移性黑色素瘤细胞的 NADPH 和 NADP+ 水平升高，表明 NADP+ 的从头生物合成增加。NADP+ 的从头生物合成是通过 NAD+ 激酶 （NADK） 催化的单一酶促反应发生的。在这里，我们表明不同的 NADK 亚型在转移性黑色素瘤细胞中差异表达，其中亚型 3 在转移中特异性上调。我们发现，与亚型 1 相比，亚型 3 在扩大 NADP（H） 库、增加抗氧化应激抵抗力和促进转移定植方面更有效。我们发现 Isoform 3 通过 NRF2 的作用被氧化应激转录上调。总之，我们的工作提出了 NADK 亚型在氧化应激抵抗和转移中以前未表征的作用，并表明 NADK 亚型 3 是转移性疾病的潜在治疗靶点。