Department of General Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100023, People's Republic of China.
Key Laboratory of Research in Pancreatic Tumor, Chinese Academy of Medical Sciences, Beijing, 100023, People's Republic of China.
J Exp Clin Cancer Res. 2023 Jun 28;42(1):155. doi: 10.1186/s13046-023-02698-x.
Pancreatic ductal adenocarcinoma (PDAC) tends to undergo distant metastasis, especially liver metastasis, leading to a poor prognosis. Metabolic remodelling and epigenetic reprogramming are two important hallmarks of malignant tumours and participate in regulating PDAC tumorigenesis and metastasis. However, the interaction between these two processes during PDAC metastasis has not been fully elucidated.
We performed metabolomics analysis to identify the critical metabolites associated with PDAC liver metastasis and focused on guanidinoacetic acid (GAA). Intracellular GAA content was significantly increased in liver metastatic PDAC cells compared to primary cancer cells in mouse xenograft tumour models. The effects of GAA supplementation and glycine amidinotransferase (GATM) knockdown on PDAC metastasis were assessed by analysing cell migration, filopodia formation, epithelial-mesenchymal transition (EMT), and in vivo metastasis in different cell and animal models. Next, ChIP‒qPCR, 3C‒qPCR, and CRISPRi/dCas9-KRAB experiments were used to validate the "epigenome-metabolome" mechanism. Finally, the results of in vitro approaches, including RNA-seq, CUT&RUN, RT‒qPCR, and western blot analyses, as well as luciferase reporter gene assay and transwell assay, revealed the GAA-c-Myc-HMGA axis and transcription-activating histone modifications reprogramming.
A high level of intracellular GAA was associated with PDAC liver metastasis. GAA could promote the migration, EMT, and liver metastasis of pancreatic cancer cells in vitro and in vivo. Next, we explored the role of GATM-mediated de novo GAA synthesis in pancreatic cancer metastasis. High expression of GATM was positively correlated with advanced N stage in PDAC. Knockdown of GATM significantly reduced the intracellular level of GAA, suppressed EMT, and inhibited PDAC liver metastasis, and these effects were attenuated by GAA supplementation. Mechanistically, we identified the active enhancers looped to the Gatm gene locus that promoted GATM expression and PDAC liver metastasis. Furthermore, we found that GAA promoted cell migration and EMT by regulating c-Myc-mediated high mobility group AT-hook protein expression. Moreover, GAA increased the H3K4me3 modification level by upregulating histone methyltransferases, which induced the transcription of metastasis-related genes, including Myc.
These findings revealed the critical role of the epigenome-metabolome interaction in regulating PDAC liver metastasis and suggested potential therapeutic strategies targeting GAA metabolism and epigenetic regulatory mechanisms.
胰腺导管腺癌（PDAC）往往发生远处转移，尤其是肝转移，导致预后不良。代谢重编程和表观遗传重编程是恶性肿瘤的两个重要标志，参与调节 PDAC 的肿瘤发生和转移。然而，PDAC 转移过程中这两个过程之间的相互作用尚未完全阐明。
我们进行了代谢组学分析，以鉴定与 PDAC 肝转移相关的关键代谢物，并重点关注胍基乙酸（GAA）。在小鼠异种移植肿瘤模型中，与原发性癌细胞相比，肝转移性 PDAC 细胞的细胞内 GAA 含量显着增加。通过分析细胞迁移、丝状伪足形成、上皮-间充质转化（EMT）以及不同细胞和动物模型中的体内转移，评估 GAA 补充和甘氨酸氨甲酰转移酶（GATM）敲低对 PDAC 转移的影响。接下来，使用 ChIP-qPCR、3C-qPCR 和 CRISPRi/dCas9-KRAB 实验验证“表观基因组-代谢组学”机制。最后，通过体外方法（包括 RNA-seq、CUT&RUN、RT-qPCR 和 Western blot 分析以及荧光素酶报告基因测定和 Transwell 测定）获得的结果，以及亮氨酸报告基因测定和 Transwell 测定，揭示了 GAA-c-Myc-HMGA 轴和转录激活组蛋白修饰的重编程。
高水平的细胞内 GAA 与 PDAC 肝转移相关。GAA 可以促进胰腺癌细胞在体外和体内的迁移、EMT 和肝转移。接下来，我们探讨了 GATM 介导的从头 GAA 合成在胰腺癌转移中的作用。GATM 的高表达与 PDAC 的晚期 N 期呈正相关。GATM 敲低显着降低细胞内 GAA 水平，抑制 EMT 并抑制 PDAC 肝转移，而 GAA 补充则减弱了这些作用。从机制上讲，我们确定了与 GATM 基因座环回的活性增强子，该增强子促进 GATM 表达和 PDAC 肝转移。此外，我们发现 GAA 通过调节 c-Myc 介导的高迁移率族 AT 钩蛋白表达来促进细胞迁移和 EMT。此外，GAA 通过上调组蛋白甲基转移酶增加 H3K4me3 修饰水平，从而诱导包括 Myc 在内的转移相关基因的转录。
这些发现揭示了表观基因组-代谢组相互作用在调节 PDAC 肝转移中的关键作用，并提出了针对 GAA 代谢和表观遗传调节机制的潜在治疗策略。
