Project 2

项目2概要 肺癌中半胱氨酸必需性的降低 癌细胞由于胱氨酸摄取增加和半胱氨酸的损失而积累显著的细胞内半胱氨酸。 自我平衡控制半胱氨酸衍生的分子对于癌细胞存活和增殖是至关重要的， 其硫部分的结果，这有利于多种功能，包括酶催化，能量 转移和氧化还原代谢。因此，我们发现许多肺癌细胞系是高度敏感的， 缺乏半胱氨酸从头合成的能力，这表明它们依赖于 外源性胱氨酸作为半胱氨酸的来源。重要的是，最近开发的半胱氨酸（E）酶消耗 细胞外胱氨酸和半胱氨酸，表明它可能对肺癌有治疗效果。 然而，细胞内代谢回路可以改变细胞对饥饿的反应， 转硫能力因此，了解半胱氨酸饥饿的补偿机制至关重要 用于肺癌中半胱氨酸的有效治疗靶向。重要的是，我们的研究结果表明， NRF2转录因子的一个重要靶点，合成机制具有谷胱甘肽非依赖性作用， 保护细胞免受半胱氨酸饥饿诱导的铁凋亡。此外，肿瘤微环境具有 显著水平的半胱氨酸替代来源，包括谷胱甘肽、胱硫醚和蛋白质， 在细胞培养中缺乏，并且可以在没有胱氨酸的情况下促进存活。这项提议的核心假设是 是肿瘤组织起源、对胱氨酸饥饿的代谢反应和肿瘤内硫源的改变 微环境影响胱氨酸在肺癌中的重要性，从而导致靶向代谢 漏洞我们将在以下具体目标中检验这一假设： 在目的1中，我们将评估组织和细胞来源对半胱氨酸代谢的影响和必要性。 在目标2中，我们将破译决定半胱氨酸限制反应性的代谢回路。 在目标3中，我们将评估肿瘤微环境中的半胱氨酸代谢。 本项目的最终目标和总体影响是描述半胱氨酸的关键决定因素 代谢和依赖性，以确定治疗干预的机会。

PROJECT 2 SUMMARY INVESTIGATING CYSTEINE ESSENTIALITY IN LUNG CANCER Cancer cells accumulate significant intracellular cysteine due to increased cystine uptake and loss of homeostatic control. Cysteine-derived molecules are crucial for cancer cell survival and proliferation as a consequence of their sulfur moiety, which facilitates diverse functions, including enzyme catalysis, energy transfer, and redox metabolism. Consistently, we have found that many lung cancer cell lines are highly sensitive to cystine starvation and lack the capacity for de novo cysteine synthesis, suggesting they are dependent on exogenous cystine as a source of cysteine. Importantly, the recently developed cyst(e)inase enzyme depletes extracellular cystine and cysteine efficiently, suggesting it may have therapeutic efficacy against lung cancer. However, intracellular metabolic circuits can modify the cellular response to starvation independent of transsulfuration capacity. Thus, understanding the compensatory mechanisms to cysteine starvation is crucial for efficient therapeutic targeting of cysteine in lung cancer. Importantly, our results suggest the glutathione synthesis machinery, an important target of the NRF2 transcription factor, has a glutathione-independent role to protect cells against cysteine starvation-induced ferroptosis. In addition, the tumor microenvironment has significant levels of alternative sources of cysteine, including glutathione, cystathionine and protein, that are lacking in cell culture and may promote survival in the absence of cystine. The central hypothesis of this proposal is that tissue of origin, metabolic responses to cystine starvation, and alteration in sulfur sources within the tumor microenvironment influence cystine essentiality in lung cancer, thereby leading to targetable metabolic vulnerabilities. We will test this hypothesis in the following specific aims: In Aim 1 we will evaluate the influence of tissue and cell of origin on cysteine metabolism and essentiality. In Aim 2 we will decipher metabolic circuits that dictate responsiveness to cysteine limitation. In Aim 3 we will evaluate cysteine metabolism in the tumor microenvironment. The ultimate goal, and the overall impact, of this project is to characterize key determinants of cysteine metabolism and dependence in lung cancer in order to define opportunities for therapeutic intervention.