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

项目摘要 我们最近发现，低，而不是高，磷酸甘油酸脱氢酶（PHGDH）的表达， 丝氨酸生物合成途径指示三阴性乳腺癌（TNBC）原发性 肿瘤的我们的初步实验表明，PHGDH的低表达导致唾液酸水平的上调。 酸生物合成途径，这反过来又激活转移所需的细胞程序。然而，催化 PHGDH的抑制不增加唾液酸的生物合成或转移，表明PHGDH的非催化作用。 PHGDH。本项目的目的是：1）研究PHGDH在调节唾液酸中的非经典作用 生物合成，2）破译指示唾液酸代谢的低-PHGDH活化的代谢重新布线， 阐明低PHGDH、高唾液酸代谢驱动转移的机制。为了确认非- 为了证明PHGDH的典型功能，我们将敲除其他丝氨酸生物合成基因，以表明它不抑制 丝氨酸生物合成驱动唾液酸上调和转移。我们将研究PHGDH蛋白- 蛋白质相互作用和亚细胞定位的PHGDH蛋白，以进一步探测其非典型功能。 低PHGDH细胞中的代谢重新布线将使用质谱方法详细阐明。我们将 也过表达从糖酵解分支的代谢途径中的基因，以确定唾液酸是否 代谢通量对碳通量转向竞争途径敏感。最后，我们初步的数据链接 高唾液酸代谢通量增加EMT标志物和p38和c-SRC的磷酸化，作为 转移我们将研究p38和SRC磷酸化在增强转移中的重要性， 研究这种联系是否是由细胞表面唾液酸流量增加或唾液酸化介导的。我们的整体 目的是阐明低PHGDH驱动的唾液酸上调作为乳腺癌的促进因素的机制， 癌症转移，这将导致新的转移生物标志物（低PHGDH，高唾液酸）， 开发转移性TNBC的新治疗策略。

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.