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

总结 不仅癌细胞而且肿瘤微环境的其他组分响应的过程 对营养条件的挑战并不为人所知。拟议的研究将提供详细的 了解PCa上皮细胞通过下调p62来分化基质的机制， 以及缺乏p62的基质如何重新编程其代谢，以产生一个更能抵抗 营养胁迫本申请基于两组初步数据：1）p62缺陷型基质细胞 重新编程其代谢以介导基质对谷氨酰胺（Gln）剥夺的抗性，并促进 甚至在Gln限制条件下PCa上皮细胞的生长; 2）基质p62被乳酸下调 由PCa上皮通过JunB介导的p62启动子抑制分泌。根据这些数据，我们 假设PCa细胞在间质中p62下调构成了PCa的肿瘤策略 上皮以获得在缺乏Gln的肿瘤下增殖所必需的代谢支持 微环境我们将在以下目标中解决癌症生物学中的这一基本问题：（1） 定义在缺乏谷氨酰胺的条件下p62缺陷如何重新编程基质代谢。我们假设 ATF 4上调是基质细胞中p62丢失重编程葡萄糖的机制的核心 代谢，以弥补缺乏谷氨酰胺。为了验证这一假设，我们将：（1A）ATF 4的机制 p62-PKCλ/1复合物的调节;（1B）定义p62缺陷如何重新编程丝氨酸/甘氨酸代谢 通过PKCλ/1-ATF 4响应Gln剥夺;（1C）定义p62缺陷如何促进Asn合成 （1D）定义p62-PKCλ/1-ATF 4信号传导如何与Gln剥夺相关; 级联调节丙酮酸代谢;（1 E）确定p62依赖性基质细胞的功能相关性， 体内PCa的代谢重编程。(2)定义肿瘤间质中PCa如何下调p62： 在这种情况下，我们将解开调节p62抑制的机制，我们将：（2A）确定乳酸- （2B）表征p62启动子中的含JunB的AP-1复合物， （2C）确定NRF 2在JunB介导的p62抑制中的作用;（2D）确定NRF 2在JunB介导的p62抑制中的生物学相关性。 已鉴定的诱导p62下调的转录因子和信号通路。这一创新 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 肿瘤间质中的重新布线和信号传导及其对PCa进展的影响。这些发现的影响将 指导旨在操纵基质代谢的新治疗策略。

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.