Role of p62 in metabolic reprograming of the tumor stroma in prostate cancer

摘要 不仅癌细胞，而且肿瘤微环境的其他成分作出反应的过程 对营养具有挑战性的条件并不为人所知。拟议的研究将提供详细的 了解前列腺癌上皮通过下调p62来分泌间质的机制， 以及缺乏p62的间质如何重新编程其新陈代谢，以产生更耐受的微环境 营养压力。这一应用基于两组初步数据：1)缺乏p62的基质细胞 重新编程它们的代谢，以介导基质对谷氨酰胺(Gln)剥夺的抵抗，并促进 前列腺癌上皮细胞在谷氨酰胺限制条件下的生长；2)乳酸下调间质p62的表达 由前列腺癌上皮细胞通过JunB介导的p62启动子抑制而分泌。根据这些数据，我们 假设Pca细胞下调间质中p62的表达构成了Pca的肿瘤策略 上皮细胞获得在缺乏谷氨酰胺的肿瘤下增殖所需的代谢支持 微环境。我们将在以下目标中解决癌症生物学中的这个基本问题：(1) 明确p62缺乏如何在谷氨酰胺缺乏的条件下重新编程基质代谢。我们假设 ATF4的上调是基质细胞中p62的丢失重新编程葡萄糖的核心机制 新陈代谢来弥补谷氨酰胺的缺乏。为了验证这一假说，我们将：(1)ATF4的机制 P62-PKCλ/ι复合体的调节；(1B)确定p62缺乏如何重新编程丝氨酸/甘氨酸代谢 通过PKCλ/ι-ATF4应答谷氨酸氨基转移酶缺失；(1C)确定p62缺乏如何促进天冬氨酸氨基转移酶的合成 通过PKCλ/ι-ATF4反应谷氨酰胺缺失；(1D)定义p62-PKCλ/ι-ATF4信号转导途径 级联调节丙酮酸代谢；(1E)决定依赖p62的基质的功能相关性 体内前列腺癌的代谢重编程。(2)确定Pca如何下调肿瘤间质中p62的表达： 在此背景下，我们将：(2A)鉴定乳酸- P62启动子上有反应的AP-1位点；(2B)表征受 乳酸；(2C)定义NRF2在JunB介导的p62抑制中的作用；(2D)定义 已确定的诱导p62下调的转录因子和信号通路。这是一项创新 该提案将通过定义代谢之间的关系来填补癌症代谢领域的一个关键空白 肿瘤间质中的重新连接和信号及其对前列腺癌进展的影响。这些发现的影响将是 指导新的治疗策略，旨在控制基质的新陈代谢。

SUMMARY The process by which not only cancer cells but also other components of the tumor microenvironment respond to nutritionally challenging conditions is not well known. The proposed study will provide a detailed understanding of the mechanisms whereby the PCa epithelium educates the stroma by downregulating p62, and how p62-deficient stroma reprograms its metabolism to generate a microenvironment more resistant to nutrient stress. This application is based on two sets of preliminary data: 1) p62-deficient stromal cells reprogram their metabolism to mediate stromal resistance to glutamine (Gln) deprivation, and promote the growth of PCa epithelial cells even under Gln-limiting conditions; 2) stromal p62 is downregulated by lactate secreted by the PCa epithelium by JunB-mediated repression of the p62-promoter. Based on these data, we hypothesize that p62 downregulation in the stroma by PCa cells constitutes a tumor strategy for the PCa epithelium to obtain the metabolic support necessary to proliferate under the Gln-deprived tumor microenvironment. We will address this fundamental problem in cancer biology in the following Aims: (1) Define how p62 deficiency reprograms stromal metabolism in Gln-deprived conditions. We hypothesize that ATF4 upregulation is central to the mechanisms whereby the loss of p62 in stromal cells reprograms glucose metabolism to compensate for the lack of Gln. To test this hypothesis, we will: (1A) Mechanisms of ATF4 regulation by the p62-PKCλ/ι complex; (1B) Define how p62 deficiency reprograms serine/glycine metabolism in response to Gln deprivation through PKCλ/ι-ATF4; (1C) Define how p62 deficiency promotes Asn synthesis in response to Gln deprivation through PKCλ/ι-ATF4; (1D) Define how the p62-PKCλ/ι-ATF4 signaling cascade regulates pyruvate metabolism; (1E) Determine the functional relevance of p62-dependent stromal metabolic reprograming in PCa in vivo. (2) Define how p62 is downregulated by PCa in the tumor stroma: To unravel the mechanisms that regulate p62 repression in this context, we will: (2A) Identify the lactate- responsive AP-1 site in the p62 promoter; (2B) Characterize the JunB-containing AP-1 complex regulated by lactate; (2C) Define the role of NRF2 in JunB-mediated p62 repression; (2D) Define the biological relevance of the identified transcription factors and signaling pathways that induce p62-downregulation. This innovative proposal will fill a key gap in the cancer metabolism field by defining the relationship between metabolic rewiring and signaling in the tumor stroma and its impact on PCa progression. The impact of these findings will instruct new therapeutic strategies aimed at manipulating the metabolism of the stroma.