Non-essential amino acids and sphingolipid diversity in cancer progression

摘要 癌细胞重新编程代谢途径，以响应其代谢途径的变化而存活和增殖。 微环境虽然致癌途径维持糖酵解代谢，以提高生存期间 在肿瘤发生中，线粒体代谢在细胞外基质（ECM）接触丧失后显著改变 和在非锚定条件下的生长。将代谢流分析（MFA）应用于肿瘤 球状体，我们已经确定了丝氨酸，丙氨酸和鞘脂代谢的特殊变化， 肿瘤细胞在这样的微环境中生长。许多肿瘤扩增或过表达磷酸羟基丙酮酸 丝氨酸脱氢酶（PHGDH）和丝氨酸合成途径中的其他酶来支持生长，尽管 该途径支持侵袭性肿瘤生长的具体机制仍不清楚。丝氨酸和 丙氨酸代谢通过鞘脂生物合成连接，其中丝氨酸棕榈酰转移酶 (SPT)在富含丙氨酸和低丝氨酸水平的情况下产生毒性脱氧鞘脂（doxSL）。 这些非典型的doxSL在锚定非依赖性生长和妥协期间以较高的速率产生 线粒体代谢以减轻球体生长。通过调节丝氨酸的产生和可用性， 丙氨酸和鞘脂，我们可以在体外和体内控制肿瘤生长。这些发现提供了一种新的， 丝氨酸剥夺限制癌细胞生长的未探索机制。该提案旨在利用 通过操纵膳食氨基酸和内源性丝氨酸合成在肿瘤中产生doxSL， 减轻肿瘤生长和转移。在目标1中，我们将应用MFA来表征线粒体和 氨基酸途径在锚定独立的增长。在目标2中，我们将量化鞘脂 在球状体生长期间，生物合成受到影响，并确定为什么doxSL物质对肿瘤细胞有毒。在 目的3：我们将设计特殊配方的饮食，通过调节doxSL来减轻肿瘤的生长和转移 单独给药或与PHGDH抑制剂联合给药时产生。我们还将设计 在肿瘤细胞中的鞘脂生物合成途径，以验证我们的中心假设。如果成功的话，这个提议 将定义一种新的机制，通过这种机制，丝氨酸剥夺限制了肿瘤的生长，可以通过以下方式加以利用： 饮食干预，并用于在临床上识别反应性肿瘤类型。

Abstract Cancer cells reprogram metabolic pathways to survive and proliferate in response to changes in their microenvironment. While oncogenic pathways sustain glycolytic metabolism to enhance survival during tumorigenesis, mitochondrial metabolism is significantly altered upon loss of extracellular matrix (ECM) contact and growth under anchorage-independent conditions. By applying metabolic flux analysis (MFA) to tumor spheroids, we have identified particular changes in serine, alanine, and sphingolipid metabolism that control tumor cell growth in such microenvironments. Many tumors amplify or overexpress phosphohydroxypyruvate dehydrogenase (PHGDH) and other enzymes within the serine synthesis pathway to support growth, though the specific mechanisms through which this pathway supports aggressive tumor growth remain unclear. Serine and alanine metabolism are linked via sphingolipid biosynthesis, where the enzyme serine palmitoyltransferase (SPT) produces toxic deoxysphingolipids (doxSLs) in the context of abundant alanine and low serine levels. These atypical doxSLs are produced at higher rates during anchorage-independent growth and compromise mitochondrial metabolism to mitigate spheroid growth. By modulating the production and availability of serine, alanine, and sphingolipids we can control in vitro and in vivo tumor growth. These findings provide a novel and unexplored mechanism through which serine deprivation limits cancer cell growth. This proposal aims to exploit the production of doxSLs in tumors by manipulating dietary amino acids and endogenous serine synthesis to mitigate tumor growth and metastasis. In Aim 1 we will apply MFA to characterize changes in mitochondrial and amino acid pathways during anchorage-independent growth. In Aim 2 we will quantify how sphingolipid biosynthesis is impacted during spheroid growth and determine why doxSL species are toxic to tumor cells. In Aim 3 we will design specifically formulated diets that mitigate tumor growth and metastasis by modulating doxSL production when administered alone or in combination with PHGDH inhibitors. We will also engineer the sphingolipid biosynthesis pathway in tumor cells to validate our central hypothesis. If successful, this proposal will define a novel mechanism through which serine deprivation limits tumor growth that can be exploited via dietary interventions and used to identify responsive tumor types in the clinic.