Examining PHGDH-mediated activation of sialic acid metabolism to drive triple-negative breast cancer metastasis

项目总结 我们最近发现，磷酸甘油脱氢酶(PHGDH)的低表达，而不是高表达 丝氨酸生物合成途径提示三阴性乳腺癌(TNBC)的转移 肿瘤。我们的初步实验表明，低PHGDH表达导致唾液酸上调 酸生物合成途径，进而激活转移所需的细胞程序。然而，催化 抑制PHGDH不会增加唾液酸的生物合成或转移，这表明对 PHGDH。本项目的目的是：1)研究PHGDH在调节唾液酸中的非典范作用 生物合成，2)破译指示唾液酸代谢的低PHGDH激活的代谢重连， 3)阐明低PHGDH、高唾液酸代谢驱动转移的机制。确认非- 典型的PHGDH功能，我们将敲除其他丝氨酸生物合成基因，以表明它并没有抑制 丝氨酸的生物合成，驱动唾液酸上调和转移。我们将研究PHGDH蛋白- 蛋白质相互作用和PHGDH蛋白的亚细胞定位，以进一步探讨其非规范功能。 低PHGDH值细胞中的代谢重新连接将使用质谱学方法详细阐明。我们会 在糖酵解分支的代谢途径中也过表达基因，以确定唾液酸是否 代谢流对碳流转移到竞争途径很敏感。最后，我们的初步数据链接 高唾液酸代谢流导致EMT标志物和p38和c-SRC磷酸化增加 转移。我们将研究p38和SRC磷酸化在促进转移和 研究这种联系是否由细胞表面唾液酸通量增加或唾液酸化所介导。我们的整体 目的：阐明低PHGDH驱动的唾液酸上调作为乳房促进剂的机制。 癌症转移，这将导致新的生物标志物(低PHGDH，高唾液酸)的转移和 转移性TNBC治疗新策略的发展。

PROJECT SUMMARY We recently discovered that low, rather than high, expression of phosphoglycerate dehydrogenase (PHGDH) in the serine biosynthesis pathway is indicative of metastasis in triple negative breast cancer (TNBC) primary tumors. Our preliminary experiments indicate that low PHGDH expression results in upregulation of the sialic acid biosynthesis pathway, which in turn activates cellular programs required for metastasis. However, catalytic inhibition of PHGDH does not increase sialic acid biosynthesis or metastasis, suggesting a non-catalytic role for PHGDH. This project aims to: 1) investigate this non-canonical role of PHGDH in modulating sialic acid biosynthesis, 2) decipher the metabolic rewiring that dictates low-PHGDH activation of sialic acid metabolism, and 3) elucidate the mechanism of low PHGDH, high sialic acid metabolism-driven metastasis. To confirm non- canonical PHGDH function, we will knock out other serine biosynthetic genes to show that it is not inhibition of serine biosynthesis that drives sialic acid upregulation and metastasis. We will investigate PHGDH protein- protein interactions and subcellular localization of PHGDH protein to further probe its non-canonical function. Metabolic rewiring in low-PHGDH cells will be elucidated in detail using mass spectrometry methods. We will also overexpress genes in metabolic pathways branching from glycolysis to determine whether sialic acid metabolic flux is sensitive to diversion of carbon flux into competing pathways. Finally, our preliminary data links high sialic acid metabolic flux to increased phosphorylation of EMT markers and p38 and c-SRC as drivers of metastasis. We will study the importance of p38 and SRC phosphorylation in potentiating metastasis and investigate whether this link is mediated by increased sialic acid flux or sialylation at the cell surface. Our overall objective is to elucidate the mechanism of low PHGDH driven sialic acid upregulation as an enabler of breast cancer metastasis, which will lead to new biomarkers (low PHGDH, high sialic acid) for metastasis and development of novel therapeutic strategies for metastatic TNBC.