Akt

引言 调节性T（Treg）细胞是免疫系统中的一种特殊T细胞亚群，负责维持免疫耐受性和防止自身免疫性疾病的发生。它们通过抑制过度的免疫反应，避免对自身组织发起攻击。Treg细胞特异性表达Foxp3转录因子，并通过分泌抑制性细胞因子（如IL-10和TGF-β）或直接与其他免疫细胞接触来抑制其活性【1】。Treg细胞在控制慢性炎症、预防自身免疫性疾病以及调节肿瘤微环境中都发挥着重要作用【2】。Treg细胞表达一系列表面受体，其中Lag3是一种类似于CD4的共受体，主要在活化的T细胞和Treg细胞中表达【3】。Lag3被认为是一种抑制性共受体，能够限制常规T细胞的增殖和IL-2的产生。有研究报道，Lag3缺陷的Treg细胞不能缓解自身免疫性脑脊髓炎，但是Lag3可能会限制自身免疫性糖尿病中Treg细胞的增殖和功能【4,5】。虽然Lag3对Treg细胞功能的调节已经被证实，但是Lag3调节Treg细胞的确切机制仍不清楚。 近日，来自美国西北大学范伯格医学院的Booki Min课题组在Immunity上发表了研究论文Inhibitory co-receptor Lag3 supports Foxp3+ regulatory T cell function by restraining Myc-dependent metabolic programming。在本研究中，作者特异性突变Treg细胞的Lag3受体，揭示了Lag3通过PI3K-Akt通路抑制Myc的表达，从而支持Treg细胞免疫抑制功能的分子机制。 为了探究Lag3在Treg细胞功能调节中具体作用，研究人员在Lag3基因位点引入了loxP位点，将Lag3基因的1-3号外显子进行flox处理，然后与Foxp3CreYFP小鼠进行交配，构建了在Treg细胞中特异性缺陷Lag3的突变（Treg△Lag3E1-3）小鼠。通过诱导实验性自身免疫性脑脊髓炎（EAE），研究发现相较于野生型小鼠，Treg△Lag3E1-3小鼠的疾病进展更快且症状更严重，表现为中枢神经系统（CNS）中Treg细胞和CD4 T细胞浸润增加，促炎细胞因子也显著增加。这些结果表明，Lag3缺失的Treg细胞功能异常，未能有效控制EAE的发展。同时，研究人员还进一步的验证了Lag3在免疫抑制和肿瘤生长调控中的作用。总的来说，Lag3在维持Treg细胞的抑制功能和调节免疫反应方面发挥重要作用，其缺失可能导致更严重的炎症反应和免疫失调。 接下来，为了揭示Lag3调节Treg细胞功能的具体机制，研究人员先对CNS中分离的Treg细胞进行了RNA-seq分析。研究发现，代谢过程是Lag3缺失的Treg细胞中主要富集的途径。GSEA分析进一步确认，Lag3缺失的Treg细胞中上调的基因高度富集在细胞代谢途径中，包括Myc靶基因、氧化磷酸化、糖酵解和脂肪酸代谢途径。Myc是多种细胞代谢过程的关键调节因子，它直接激活几乎所有编码糖酵解酶的基因。在Lag3缺失的Treg细胞中，Myc表达高于对照组且与糖酵解相关的基因表达显著增加，与此相对应的是糖酵解活性增加。此外，在Lag3缺失的Treg细胞中敲低Myc的表达，糖酵解活性受到明显抑制，Treg细胞的免疫抑制功能得到恢复。研究人员还探究了Lag3抑制Myc表达的分子机制。他们发现Lag3胞质结构域缺失导致Myc及其代谢靶基因的过度表达，进而引发Treg细胞的代谢失调。这些结果表明，Lag3通过控制Myc的表达来调节Treg细胞的代谢和功能，Myc相关的代谢变化直接影响Treg细胞在体内的抑制功能。 研究人员还探究了Lag3抑制Myc表达的分子机制。他们发现Lag3胞质结构域缺失导致Myc及其代谢靶基因的过度表达，进而引发Treg细胞的代谢失调。之前的研究表明，PI3K-Akt信号通路在调控Myc表达中起重要作用，并且Lag3缺失在其他T细胞中能增强Akt磷酸化。因此作者推测Lag3可能通过PI3K-Akt信号通路抑制了Treg细胞中Myc的表达。为了证实这个推测，研究人员分析了Lag3缺失的Treg细胞中PI3K信号的激活情况以及使用PI3K-Akt通路的相关抑制剂处理细胞。结果表明，Lag3突变导致的PTEN下调、Rictor上调和Akt的异常磷酸化共同作用，引发Treg细胞的代谢失调和抑制功能减弱。当抑制PI3K和Rictor可以有效降低Myc的表达，恢复Lag3缺失的Treg细胞正常代谢活动，并改善其免疫抑制功能。 文章的最后，研究人员详细的分析了Lag3对Myc的调控是如何影响Treg细胞的代谢活动。前面介绍到Lag3的缺失会导致Treg细胞的糖酵解活性增强，一个显著特征是细胞外酸化率增加，而乳酸脱氢酶A（Ldha）是介导这种状况发生的关键基因，并且Ldha也是Myc的靶基因之一。因此，研究人员对Ldha的功能进行了分析。结果表明，Lag3缺失会导致Ldha的表达增加，这与Myc的表达升高相一致，乳酸分泌也随之增加。抑制Ldha的活性能够恢复Lag3缺失导致的Treg细胞功能障碍以及代谢异常，从而揭示了Myc-Ldha轴在Treg细胞功能中的关键作用。 模式图（Credit: Immunity） 总的来说，这篇文章揭示了Lag3共受体调节Treg细胞免疫抑制功能的具体机制，Lag3通过PI3K-Akt信号通路抑制Myc的表达，当Lag3缺失后Myc表达升高并激活下游代谢基因的表达，改写了Treg细胞的代谢进而影响了Treg细胞的抑制性功能。 参考文献 1. Sakaguchi, S., Yamaguchi, T., Nomura, T., and Ono, M. (2008). Regulatory T cells and immune tolerance. Cell 133, 775–787. 2. Vignali, D.A.A., Collison, L.W., and Workman, C.J. (2008). How regulatory T cells work. Nat. Rev. Immunol. 8, 523–532. 3. Andrews, L.P., Marciscano, A.E., Drake, C.G., and Vignali, D.A.A. (2017). LAG3 (CD223) as a cancer immunotherapy target. Immunol. Rev. 276, 80–96. 4. Kim, D., Le, H.T., Nguyen, Q.T., Kim, S., Lee, J., and Min, B. (2019). Cutting Edge: IL-27 Attenuates Autoimmune Neuroinflammation via Regulatory T Cell/Lag3-Dependent but IL-10-Independent Mechanisms In Vivo. J. Immunol. 202, 1680–1685. 5. Zhang, Q., Chikina, M., Szymczak-Workman, A.L., Horne, W., Kolls, J.K., Vignali, K.M., Normolle, D., Bettini, M., Workman, C.J., and Vignali, D.A.A. (2017). LAG3 limits regulatory T cell proliferation and function in autoimmune diabetes. Sci. Immunol. 2, eaah4569. https://doi-org.libproxy1.nus.edu.sg/10.1016/j.immuni.2024.08.008 责编|探索君 排版|探索君 来源|BioArt End 往期精选 围观 一文读透细胞死亡(Cell Death) | 24年Cell重磅综述（长文收藏版） 热文 Cell | 是什么决定了细胞的大小？ 热文 Nature | 2024年值得关注的七项技术 热文 Nature | 自身免疫性疾病能被治愈吗？科学家们终于看到了希望 热文 CRISPR技术进化史 | 24年Cell综述

SOUTH SAN FRANCISCO, CA, USA I October 30, 2024 I TheRas, Inc. d/b/a BridgeBio Oncology Therapeutics (“BBOT” or the “Company”), a clinical-stage biopharmaceutical company focused on RAS-pathway malignancies, has announced that the first patient has been dosed with BBO-10203 in the BREAKER-101 trial. BBO-10203 is a first-in-class orally bioavailable RAS:PI3Ka breaker that blocks the interaction between RAS and PI3Kα to inhibit PI3Kα-AKT signaling in tumors, without directly inhibiting the catalytic activity of PI3Kα. “I am thrilled to partner with BBOT to bring a potentially transformable new therapeutic to the clinic,” said Dr. Minal Barve, Chief Medical Officer and Principal Investigator at Mary Crowley Cancer Research, Dallas, TX. “BBO-10203 represents a first-in-class drug with potential to address high unmet medical needs and change the landscape of cancer care. We look forward to evaluating BBO-10203 in the BREAKER-101 trial.” BBO-10203 was designed to bind covalently and selectively to the RAS-binding domain (RBD) of PI3Kα. This selective inhibition is agnostic to the mutational status of PI3Kα and RAS, and in preclinical models, results in complete inhibition of RAS-driven pAKT signal at single digit nanomolar concentration. Additionally, no hyperglycemia was observed in preclinical species treated with BBO-10203. The discovery of BBO-10203 was the result of a collaboration between the RAS Initiative at Frederick National Laboratory, Lawrence Livermore National Laboratory, and BBOT. “BBO-10203 is a first-in-class program that inhibits the interaction of the two most mutated oncogenes in human cancer, and it will allow us to test, for the first time, the importance of RAS-coordinated activation of the MAPK and AKT signaling pathways,” said Pedro Beltran, PhD, Chief Scientific Officer of BBOT. “The discovery of BBO-10203 was made possible by the dedicated collaboration between academic, national laboratory, and industry experts that synergized to advance medicines for patients suffering from cancer.” The BREAKER-101 trial will enroll patients globally with locally advanced or metastatic HER2-positive breast cancer, HR-positive/HER2-negative breast cancer, KRAS mutant advanced colorectal cancer, and KRAS mutant advanced non-small cell lung cancer. “There is a tremendous opportunity to improve the standard of care in oncology by inhibiting oncogenic pAKT signaling without the metabolic side effects observed with kinase inhibitors, and the initiation of the Phase 1 study of BBO-10203 marks an important milestone in this regard,” said Yong (Ben) Ben, MD, Chief Medical and Development Officer of BBOT. “The second IND within six months of establishing BBOT clearly demonstrates our team’s capability in advancing our novel programs into the clinic. This novel mechanism and scientific rationale behind it will allow tremendous combination opportunities that optimally inhibit both pAKT and pERK – an approach we hope will bring unprecedented benefit to patients with RAS-driven cancers.” About TheRas, Inc. d/b/a BridgeBio Oncology Therapeutics (BBOT) BridgeBio Oncology Therapeutics (BBOT) is a clinical-stage biopharmaceutical company advancing a next generation pipeline of novel small molecule therapeutics targeting RAS and PI3K malignancies. Initially formed as a subsidiary of BridgeBio, BBOT completed a $200M private financing with external investors in 2024 with the goal of improving outcomes for patients with cancers driven by the two most prevalent oncogenes in human tumors. For more information visit bridgebiooncology.com . SOURCE: BridgeBio Oncology Therapeutics

AKTive-001 is a Phase 1/1b study of ALTA2618 in adults with AKT1 E17K-mutant solid tumors ALTA2618 is the first clinical mutant-selective inhibitor of AKT SAN DIEGO, CA, USA I October 30, 2024 I Alterome Therapeutics, Inc. , a clinical stage biopharmaceutical company pioneering the development of next generation, small molecule targeted therapies for the treatment of cancer, today announced the dosing of the first patient in AKTive-001, a Phase 1/1b trial of ALTA2618 in adults with AKT1 E17K-mutant advanced solid tumors. ALTA2618 is the first mutant-selective allosteric inhibitor of AKT1 E17K and is designed to avoid on-target toxicities associated with inhibition of AKT family kinases. AKT1 E17K is a clinically validated oncogene that drives ~5% of breast cancer, particularly hormone positive disease, and 1-2% of all cancer, including endometrial (~3%) and prostate (~2%) cancers. “Dosing the first patient in the AKTive-001 trial marks a significant milestone for Alterome as we advance the first program from our mutation-selective and isoform-selective discovery pipeline to the clinic,” said Eric Murphy, Ph.D., co-founder and CEO of Alterome Therapeutics. “ALTA2618 was designed to selectively target the AKT1 E17K mutation by pioneering a novel covalent approach to capture the lysine mutation. From concept to clinic, ALTA2618 illustrates the relentless execution of our team and dedication to developing novel mutation-selective therapies that will improve outcomes for patients with cancer.” AKTive-001 is a Phase 1/1b, open-label, dose escalation and multiple expansion cohort study evaluating ALTA2618 as an oral monotherapy. The study will evaluate the safety, tolerability, pharmacokinetics, and preliminary clinical activity of ALTA2618 in patients aged 18 years or above with AKT1 E17K-mutated advanced unresectable or metastatic solid tumors (NCT06533059). Additional clinical sites across Europe, Asia and Australia will initiate enrollment over the next year. About Alterome Therapeutics, Inc. Alterome Therapeutics, Inc. is a precision oncology biotech developing alteration-specific therapeutics to address high-value and validated oncogenic drivers. The company is led by an expert team of precision oncology R&D leaders with a history of developing marketed oncology small molecule drugs. For more information, visit www.alterome.com . Follow us on LinkedIn and Twitter . SOURCE: Alterome Therapeutic