Leveraging the GTP Biosynthetic Pathway for Anti-Tumor Therapies

侵袭是包括乳腺癌在内的所有癌症中最有害的特征之一，因为它允许细胞 逃离原发部位，在远处器官形成转移。尽管在预防和早期预防方面取得了进展 在病变检测方面，与转移性乳腺癌相关的死亡率仍然极高。这是 对于出现三重阴性乳腺癌(TNBC，特征是缺乏 ER、PR和Her2的表达)，这是乳腺癌中最具侵袭性和最致命的亚型， 到目前为止还缺乏治疗干预的具体目标。了解以下机制 促进肿瘤细胞的侵袭将使我们能够设计更有效的治疗策略来预防或 减少转移。 我们小组已经建立了GTP代谢和肿瘤细胞侵袭性之间的基本联系； 我们揭示了GTP及其代谢酶(GME)在肿瘤进展和转移中的关键作用 潜力。我们已经为细胞内GTP开发了独特的荧光记者，这使得我们能够 确定在活细胞中，GTP在细胞内的分布并不均匀，并提出了假说 GTP的局部浓度可以影响GTP依赖的过程。特别是，我们之前已经 表明GTP代谢途径的遗传或药物调节深深地影响着 Rho家族小GTP酶的激活状态及其与肿瘤细胞侵袭能力的关系。因此，在 目的1探索一种基于GME亚细胞定位的G蛋白激活新机制。 我们的初步结果表明，GTP从头产生的限速酶--肌醇 单磷酸脱氢酶2(IMPDH2)在对细胞迁移至关重要的细胞膜位置富含 和侵袭性(即灶性粘连、FA和内陷)。IMPDH2在这些地点的作用实际上是 没有特征的。因此，在目标2中，我们将评估IMPDH2在FA和FA中的催化和结构作用。 不定足的形成，以及粘着斑激酶(FAK)引导的致癌运动。 对GTP代谢酶转录调控的了解还远未完全。身份识别 GTP生物合成途径的转录主调控子可作为药理学靶点 将提供一种更有效的方式来抑制这一途径。我们的初步结果表明，类似克鲁佩尔的 因子9(KLF9)和芳香烃受体(AHR)在转录调控中发挥拮抗作用 GTP代谢酶，KLF9抑制，而AHR诱导GTP产生。因此，在目标3中，我们 将阐明这一调节，并探索药物治疗来调节这些活性 转录因子。

Invasion is one of the most detrimental features of all cancers, including breast cancer, as it allows cells to escape the primary site and form metastases at distant organs. Despite progress in prevention and early lesions detection, the mortality associated with metastatic breast cancer is still extremely high. This is especially true for patients presenting with triple negative breast cancer (TNBC, characterized by lack of expression of ER, PR, and Her2 ), which is the most aggressive and deadliest subtype of breast cancer and the one that so far lack specific targets for therapeutic intervention. Understanding the mechanisms that facilitate the invasion of tumor cells will enable us to design more efficient therapeutic strategies to prevent or reduce metastasis. Our group has established a fundamental connection between GTP metabolism and tumor cell invasiveness; we have unveiled GTP and its metabolic enzymes (GME) as key players in tumor progression and metastatic potential. We have developed unique fluorescent reporters for intracellular GTP that have allowed us to determine that, in live cells, the intracellular GTP distribution is not uniform, and brought forward the hypothesis that local concentration of GTP can influence GTP-dependent processes. In particular, we have previously shown that genetic or pharmacological modulation of the GTP metabolic pathway deeply affected the activation status of small GTPases of the RHO-family and, with it, the tumor cells' invasive capability. Thus, in Aim 1 we will explore a novel mechanism of G-proteins activation based on GME subcellular localization. Our preliminary results showed that the rate-limiting enzyme for GTP de novo production, inositol monophosphate dehydrogenase 2 (IMPDH2) enriches at cell membrane sites that are critical for cell migration and invasion (namely focal adhesion, FA, and invadopodia). The role of IMPDH2 at these sites is virtually uncharacterized. Thus, in Aim 2 we will assess the catalytic and structural role of IMPDH2 in FA and invadopodia formation, as well as in focal adhesion kinase (FAK)-directed oncogenic motility. The understanding of GTP metabolic enzymes transcriptional regulation is far from complete. Identification of transcriptional master regulators of the GTP biosynthetic pathway that could be pharmacologically targeted would offer a more efficient way of suppressing this pathway. Our preliminary results suggest that Kruppel-like factor 9 (KLF9) and aryl hydrocarbon receptor (AHR) play antagonistic roles in the transcriptional regulation of GTP metabolic enzymes, with KLF9 suppressing, whereas AHR inducing GTP production. Thus, in Aim 3 we will elucidate this regulation and explore pharmacological treatments to regulate the activity of these transcription factors.