The aim of this study was to investigate the underlying molecular mechanism behind the promotion of cell survival under conditions of glucose deprivation by -lactate. To accomplish this, we performed tissue microarray and immunohistochemistry staining to analyze the correlation between the abundance of pan-Lysine lactylation and prognosis. evaluations of tumor growth were conducted using the KPC and nude mice xenograft tumor model. For mechanistic studies, multi-omics analysis, RNA interference, and site-directed mutagenesis techniques were utilized. Our findings robustly confirmed that -lactate promotes cell survival under glucose deprivation conditions, primarily by relying on GLS1-mediated glutaminolysis to support mitochondrial respiration. Mechanistically, we discovered that -lactate enhances the NMNAT1-mediated NAD salvage pathway while concurrently inactivating p-38 MAPK signaling and suppressing DDIT3 transcription. Notably, Pan-Kla abundance was significantly upregulated in patients with Pancreatic adenocarcinoma (PAAD) and associated with poor prognosis. We identified the 128th Lysine residue of NMNAT1 as a critical site for lactylation and revealed EP300 as a key lactyltransferase responsible for catalyzing lactylation. Importantly, we elucidated that lactylation of NMNAT1 enhances its nuclear localization and maintains enzymatic activity, thereby supporting the nuclear NAD salvage pathway and facilitating cancer growth. Finally, we demonstrated that the NMNAT1-dependent NAD salvage pathway promotes cell survival under glucose deprivation conditions and is reliant on the activity of Sirt1. Collectively, our study has unraveled a novel molecular mechanism by which -lactate promotes cell survival under glucose deprivation conditions, presenting a promising strategy for targeting lactate and NAD metabolism in the treatment of PAAD.

中文翻译：

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乳酸增强 NMNAT1 乳酰化以维持核 NAD+ 挽救途径并促进胰腺腺癌细胞在葡萄糖剥夺条件下的存活

本研究的目的是调查β-乳酸在葡萄糖剥夺条件下促进细胞存活的潜在分子机制。为了实现这一目标，我们进行了组织微阵列和免疫组织化学染色，以分析泛赖氨酸乳酰化丰度与预后之间的相关性。使用KPC和裸鼠异种移植肿瘤模型对肿瘤生长进行评估。对于机制研究，利用了多组学分析、RNA 干扰和定点诱变技术。我们的研究结果有力地证实，β-乳酸在葡萄糖剥夺条件下促进细胞存活，主要是通过依赖 GLS1 介导的谷氨酰胺分解来支持线粒体呼吸。从机制上讲，我们发现β-乳酸增强了 NMNAT1 介导的 NAD 挽救途径，同时失活 p-38 MAPK 信号传导并抑制 DDIT3 转录。值得注意的是，胰腺腺癌 (PAAD) 患者中 Pan-Kla 丰度显着上调，且与不良预后相关。我们将 NMNAT1 的第 128 个赖氨酸残基确定为乳酰化的关键位点，并揭示 EP300 是负责催化乳酰化的关键乳酰转移酶。重要的是，我们阐明了 NMNAT1 的乳酰化增强了其核定位并维持酶活性，从而支持核 NAD 挽救途径并促进癌症生长。最后，我们证明 NMNAT1 依赖性 NAD 挽救途径可促进葡萄糖剥夺条件下的细胞存活，并且依赖于 Sirt1 的活性。总的来说，我们的研究揭示了一种新的分子机制，β-乳酸通过该机制在葡萄糖剥夺条件下促进细胞存活，为治疗 PAAD 中的乳酸和 NAD 代谢提供了一种有前途的策略。