PDE3A

An overactive enzyme that causes an inherited form of high blood pressure also appears to protect against hypertension-induced cardiac damage. A team of researchers explains how this could fundamentally change the way hearts can be protected from damage. For decades, scientists in Berlin have been researching a strange hereditary condition that results in half the members of certain families having unusually short fingers and extremely high blood pressure. If left untreated, the affected patients usually die of a stroke at the age of 50 years. Researchers at the Max Delbrück Center (MDC) in Berlin identified the cause of the disease back in 2015 and were able to prove their hypothesis five years later using animal models: a mutation in the phosphodiesterase 3A gene (PDE3A) causes its encoded enzyme to become overactive, affecting bone growth and causing blood vessel hyperplasia -- resulting in elevated blood pressure. Immune to hypertension-related damage "High blood pressure almost always leads to the heart becoming weaker," says Dr. Enno Klußmann, head of the Anchored Signaling Lab at the Max Delbrück Center and a scientist at the German Centre for Cardiovascular Research (DZHK). As it has to pump against a higher pressure, Klußmann explains, the organ tries to strengthen its left ventricle. "But ultimately, this results in the thickening of the heart muscle -- known as cardiac hypertrophy -- which can lead to heart failure greatly decreasing its pumping capacity." But in the hypertension patients with the shortened fingers and mutated PDE3A gene, this doesn't happen. "For reasons that are now partly -- but not yet fully -- understood, their hearts appear immune to the damage that usually results from high blood pressure," says Klußmann. The study, which has been published in the journal Circulation, is the result of a collaboration between researchers at the Max Delbrück Center, Charité -- Universitätsmedizin Berlin, and the DZHK. In addition to Klußmann, professors Norbert Hübner and Michael Bader from the Max Delbrück Center were involved as final authors, along with Dr. Sylvia Bähring from the Experimental and Clinical Research Center (ECRC) -- a joint institution of Charité and the Max Delbrück Center. Together with 43 other researchers from Berlin, Bochum, Heidelberg, Kassel, Limburg, Lübeck, Canada, and New Zealand, the team has now reported its findings on the protective effects of the gene mutation -- and why these results could change the way heart failure is treated in the future. The publication has four first authors, three of whom conduct research at the Max Delbrück Center and one at the ECRC. Two mutations with the same effect The scientists performed their tests on human patients with hypertension and brachydactyly (HTNB) syndrome -- i.e., high blood pressure and abnormally short digits -- as well as on rat models and heart muscle cells. The cells were grown from specially engineered stem cells known as induced pluripotent stem cells. Before testing began, researchers altered the PDE3A gene in the cells and the animals to mimic HTNB mutations. "We came across a previously unknown PDE3A gene mutation in the patients we examined," reports Bähring. "Previous studies had always shown the mutation in the enzyme to be located outside the catalytic domain -- but we have now found a mutation right in the center of this domain." Surprisingly, both mutations have the same effect in that they make the enzyme more active than usual. This hyperactivity ramps up the degradation of one of the cell's important signaling molecules known as cAMP (cyclic adenosine monophosphate), which is involved in the contraction of the heart muscle cells. "It is possible that this gene modification -- regardless of its location -- causes two or more PDE3A molecules to cluster together and thus work more effectively," Bähring suspects. The proteins stay the same The researchers used a rat model -- created with CRISPR-Cas9 technology by Michael Bader's lab at the Max Delbrück Center -- to try to better understand the effects of the mutations. "We treated the animals with the agent isoproterenol, a so-called beta-receptor agonist," says Klußmann. Such medications are sometimes used in patients with end-stage heart failure. Isoproterenol is known to induce cardiac hypertrophy. "Yet surprisingly, this occurred in the gene-modified rats in a manner similar to what we observed in the wild-type animals. Contrary to what we expected, the existing hypertension did not aggravate the situation," reports Klußmann. "Their hearts were quite obviously protected from this effect of the isoproterenol." In further experiments, the team investigated whether proteins in a specific signaling cascade of the heart muscle cells changed as a result of the mutation and if so which ones. Through this chain of chemical reactions, the heart responds to adrenaline and beats faster in response to situations such as excitement. Adrenaline activates the cells' beta receptors, causing them to produce more cAMP. PDE3A and other PDEs stop the process by chemically altering cAMP. "However, we found little difference between mutant and wild-type rats at both the protein and the RNA levels," Klußmann says. More calcium in the cytosol The conversion of cAMP by PDE3A does not occur just anywhere in the heart muscle cell, but near a tubular membrane system that stores calcium ions. A release of these ions into the cytosol of the cell triggers muscle contraction, thus making the heart beat. After the contraction, the calcium is pumped back into storage by a protein complex. This process is also regulated locally by PDE. Klußmann and his team hypothesized that because these enzymes are hyperactive in the local region around the calcium pump, there should be less cAMP -- which would inhibit the pump's activity. "In the gene-modified heart muscle cells, we actually showed that the calcium ions remain in the cytosol longer than usual," says Dr. Maria Ercu, a member of Klußmann's lab and one of the study's four first authors. "This could increase the contractile force of the cells." Activating instead of inhibiting "PDE3 inhibitors are currently in use for acute heart failure treatment to increase cAMP levels," Klußmann explains. Regular therapy with these drugs would rapidly sap the heart muscle's strength. "Our findings now suggest that not the inhibition of PDE3, but -- on the contrary -- the selective activation of PDE3A may be a new and vastly improved approach for preventing and treating hypertension-induced cardiac damage like hypertrophic cardiomyopathy and heart failure," Klußmann says. But before that can happen, he says, more light needs to be shed on the protective effects of the mutation. "We have observed that PDE3A not only becomes more active, but also that its concentration in heart muscle cells decreases," the researcher reports, adding that it is possible that the former can be explained by oligomerization -- a mechanism that involves at least two enzyme molecules working together. "In this case," says Klußmann, "we could probably develop strategies that artificially initiate local oligomerization -- thus mimicking the protective effect for the heart."

日前，美国癌症研究协会（AACR）2022年会落下帷幕。AACR是全球规模最大的癌症研究会议之一，聚集了来自全球各地高质量的肿瘤学研究和临床进展。在其“New Drugs on the Horizon”系列报告中，多家生物技术和医药公司首次公布了在研疗法的分子结构。 1、候选药物：BAY 2666605，首款抗癌PDE3A-SLFN12分子胶 研发机构：拜耳，Broad研究所 BAY 2666605是由拜耳（Bayer）和Broad研究所的科学家联合开发的一款促进PDE3A和SLFN12构成复合体的分子胶。PDE3A和SLFN12是在多种癌症中过度表达的两种蛋白。PDE3A和SLFN12的结合会刺激SLFN12的RNA酶活性，导致其特异性底物tRNA-Leu-TAA的切割，而tRNA-Leu-TAA的切割导致核糖体停顿，抑制蛋白合成并导致癌细胞死亡。 BAY 2666605已经进入1期临床试验阶段，用于治疗同时表达PDE3A和SLFN12的晚期实体瘤患者，包括黑色素瘤、卵巢癌和肉瘤。 2、候选药物：CFT8634，靶向BRD9蛋白降解剂 研发机构：C4 Therapeutics CFT8634靶向的BRD9蛋白是控制染色质重塑的SWI/SNF复合体的重要组分，这一复合体在多种癌症中经常出现突变。CFT8634是一款双特异性分子，它能够将BRD9和E3泛素链接酶CRBN连接在一起，在BRD9蛋白上添加泛素修饰，导致BRD9的特异性降解。 在滑膜肉瘤的临床前模型中，CFT8634表现出持续降低肿瘤体积的效果。这款在研疗法已经获得美国FDA授予治疗滑膜肉瘤的孤儿药资格，其IND申请在今年2月底获得许可，预计在上半年开始针对滑膜肉瘤患者的1期临床试验。 3、C4 Therapeutics公司还在AACR大会上公布了在研CRBN E3连接酶调节剂（CELMoDs）CFT7455作为单药疗法，治疗复发/难治性多发性骨髓瘤患者的初步临床试验结果。CFT7455通过与E3泛素连接酶CRBN结合，促进IKZF1/3的降解。 4、候选药物：FHD-286，BAF复合体别构抑制剂 研发机构：Foghorn Therapeutics FHD-286是一款潜在“first-in-class”，BAF复合体口服抑制剂。BAF复合体（又名SWI/SNF复合体）在对DNA的表观遗传学调控方面起到重要作用。在很多癌症中，表观遗传学调控的变化导致致癌基因的过度表达或者抑癌基因的表达受到抑制，从而引发细胞的癌变。FHD-286通过选择性别构抑制BAF复合体中的ATP酶成分SMARCA4和SMARCA2，抑制BAF的功能。 临床前研究显示，葡萄膜黑色素瘤和血液癌症细胞系对BAF复合体抑制剂尤为敏感。目前，FHD-286正在两项1期临床试验中接受检验，用于治疗复发/难治性急性髓系白血病和转移性葡萄膜黑色素瘤。该公司还在利用靶向蛋白降解的策略来降解BAF复合体，其靶向降解BRD9的在研疗法FHD-609也已经进入临床试验阶段。 5、候选药物：EZM0414，组蛋白甲基转移酶SETD2抑制剂 研发机构：Epizyme EZM0414和上面提到的FHD-286和CFT8634一样，都是旨在通过靶向表观遗传学机制来治疗癌症。Epizyme公司致力于靶向表观遗传学调控开发创新疗法。其EZH2抑制剂Tazverik是首款获得FDA批准的EZH2抑制剂，EZH2是组蛋白甲基转移酶PRC2的催化亚基。Tazverik的获批也为靶向表观遗传学机制治疗癌症的策略做出了临床验证。 EZM0414是一款潜在“first-in-class”SETD2抑制剂。SETD2是一种组蛋白甲基转移酶，与PCR2具有类似的作用。EZM0414已经获得美国FDA授予的快速通道资格，用于治疗复发或难治性弥漫性大B细胞淋巴瘤（DLBCL）。Epizyme已经启动1期临床试验，检验它在多发性骨髓瘤和DLBCL患者中的效果。 6、候选药物：ABBV-CLS-484，磷酸酶PTPN2/N1抑制剂 研发机构：AbbVie，Calico，Broad研究所 PTPN2/N1是蛋白酪氨酸磷酸酶，它们的作用是去除酪氨酸上添加的磷酸基团。在癌症免疫反应的多个步骤中起到重要作用。比如PTPN2可以调节耗竭CD8阳性T细胞的产生。磷酸酶是很难于靶向的靶点，由于它的催化亚基部分高度保守，靶向催化亚基的药物很容易同时抑制其它磷酸酶的活性，导致毒副作用。ABBV-CLS-484是一款靶向PTPN2活性位点的抑制剂，能够在pM水平抑制其活性。目前艾伯维已经开展1期临床试验，检验它与免疫检查点抑制剂联用的效果。 7、候选药物：KSQ-4279，潜在“first-in-class”别构USP1抑制剂 研发机构：KSQ Therapeutics KSQ-4279是一款强力选择性USP1别构抑制剂，USP1是泛素特异性加工（ubiquitin-specific processing）蛋白家族的一员，在DNA损伤反应中具有重要作用。KSQ Therapeutics公司使用其基于CRISPR筛选的CRISPRomics技术平台发现，USP1是靶向特定基因组不稳定癌症的创新合成致死靶点。 KSQ-4279的别构抑制的特征让它对USP1具有很高的选择性，显著优于其它USP蛋白家族。临床前研究显示它作为单药或者与PARP抑制剂联用，在多款携带BRCA突变或同源重组缺陷的癌症模型中显示出疗效。 而且，功能性基因组耐药性筛选发现，驱动对USP1抑制剂耐药性的遗传因素与驱动PARP抑制剂耐药性的遗传因子并不重叠。这意味着这一组合可能延缓或预防耐药性的产生。目前KSQ Therapeutics已经启动1期临床试验，在晚期实体瘤患者中评估它的效果。 8、候选药物：MRTX0902，针对KRAS驱动癌症的SOS1抑制剂 研发机构：Mirati Therapeutics 过去几年中，靶向KRAS G12C的努力获得重大突破，安进公司的sotorasib和Mirati公司的adagrasib（MRTX849）都在临床试验中表现出活性。SOS蛋白是一款鸟嘌呤核苷酸交换因子（GEF），它在激活RAS家族蛋白方面起到重要作用。 MRTX0902是一款强力选择性SOS1口服抑制剂。Mirati公司的科学家采用基于结构的设计，发现了一系列化合物可以扰乱SOS1和KRAS之间的相互作用，阻止SOS1介导GTP取代与KRAS结合的GDP。与GDP结合的KRAS处于失活状态，而adagrasib能够与处于失活状态的KRAS G12C结合，抑制它的活性。因此，MRTX0902与adagrasib联用有望进一步增强adagrasib的效果。 9、候选疗法：GDC-6036，口服KRAS G12C共价抑制剂 研发机构：基因泰克 罗氏旗下基因泰克公司开发的GDC-6036是一款KRAS G12C共价抑制剂，它与安进公司的sotorasib和Mirati公司开发的adagrasib具有相同的作用机制，通过与失活状态的KRAS G12C结合，将KRAS锁定在失活状态。目前它正在1期临床试验中作为单药，以及与其它抗癌疗法联用，治疗非小细胞癌、结直肠癌等携带KRAS G12C突变的癌症类型。 10、候选药物：NPX800，热休克因子1（HSF1）抑制剂 研发机构：伦敦癌症研究所，Nuvectis Pharma HSF1是一款应激诱导的转录因子，在激发真核细胞热休克反应中起到关键性作用。在癌细胞中，HSF1被“劫持”用于激发与经典热休克反应类似的基因表达。HSF1信号通路在肿瘤发生中起到重要作用，是多项研究验证的抗癌药物靶点。 伦敦癌症研究所的研究人员通过表型筛选，最初发现了抑制HSF1活性的化合物，并且与Nuvectis Pharma合作将其优化成为临床期候选药物。NXP800是一款潜在“first-in-class”，口服HSF1信号通路抑制剂。目前它正在1期临床试验中接受评估，治疗晚期实体瘤患者。 参考资料： [1] New Drug Candidates at AACR New Orleans 2022. Retrieved April 11, 2022, from https://drughunter.com/new-drug-candidates-at-aacr-new-orleans-2022/ [2] KSQ Therapeutics To Present Data At The American Association For Cancer Research (AACR) 2022 Annual Meeting. Retrieved April 11, 2022, from https://ksqtx.com/news-events/ksq-therapeutics-to-present-data-at-the-american-association-for-cancer-research-aacr-2022-annual-meeting/ [3] NXP800: A first-in-class, orally active, smallmolecule HSF1* pathway inhibitor. Retrieved April 12, 2022, from https://nuvectis.com/wp-content/uploads/2022/04/NXP800-New-Drugs-on-the-Horizon_-AACR-2022.pdf 内容来源于网络，如有侵权，请联系删除，谢谢