Enzyme Inhibitors as Potential Anticancer and Antiviral

A.蛋白激酶C项目 蛋白激酶C包括参与细胞信号调节的10多种同工酶的家族。根据它们的结构和调节，它们被分为3个亚类。经典或钙依赖性（cPKC）、新型或钙非依赖性（nPKC）和非典型或二酰基甘油（DAG）/佛波酯非依赖性（aPKC）。前两种类型响应于第二信使DAG的释放，第二信使DAG将酶从它们的非活性胞质位置募集到膜，在膜中它们变得变构激活。用佛波醇酯也可以达到类似的效果，佛波醇酯对PKC的结合亲和力比DAG高得多。正是由于这个原因，佛波醇酯已成为研究PKC激活作用的优选试剂。另一方面，我们已经合成了一组合理设计的DAG-内酯，尽管它们的结构简单，表现为高度有效的PKC配体，能够显示相当的，虽然不同的活动，佛波醇酯，有时甚至超过他们的效力。去年，我们报道了第一个同工酶特异性PKC激活剂的设计，能够诱导PKC-α的细胞膜和PKC-δ的核膜的独家易位。该化合物还能够在人前列腺癌细胞中诱导强烈的细胞凋亡，并且在60细胞系NCI筛选中发现了对小细胞癌和黑色素瘤细胞的有效和选择性抑制。该化合物的毒理学研究正在DTP的主持下进行。 B。DNA甲基转移酶项目（Zebularine）。 我们已经证明了zebularine [2（1H）-嘧啶酮核苷]在10 T1/2细胞中诱导肌原性表型的能力，这是DNA甲基化抑制剂特有的现象。我们还提供了证据表明，zebularine可以重新激活沉默的p16基因和脱甲基的T24膀胱癌细胞系在体外以及在BALB/c nu/nu小鼠的肿瘤生长的启动子区域。因此，一个密集的合成计划已经开始，旨在了解zebularine及其类似物的结构-活性关系。令人惊讶的是，尽管2 '-脱氧泽布拉林-5'-三磷酸被怀疑是关键代谢物，但2 '-脱氧泽布拉林是无活性的。几种亲脂性增加的类似物的合成正在进行中，以提高生物利用度并促进2 '-脱氧zebularine-5'-三磷酸的形成。 蛋白激酶C同工酶。银鲛激活/抑制，药物设计。锌指。DNA甲基化，肿瘤抑制基因。凋亡

A. Protein Kinase C Projet. Protein kinase C comprises a family of more than 10 isozymes involved in the regulation of cell signalling. They have been grouped into 3 subclasses according to their structure and regulation. Classical or calcium-dependent (cPKC), novel or calcium-independent (nPKC) and atypical or diacylglycerol (DAG)/phorbol ester-independent (aPKC). The first two types respond to the release of the second messenger DAG, which recruits the enzymes from their inactive cytosolic location to the membrane where they become allosterically activated. A similar effect can be achieved pharmacologically with the phorbol esters, which have substantially higher binding affinity for PKC than the DAGs. It is for that reason, that the phorbol esters have become the preferred agents to study the effects of PKC activation. On the other hand, we have synthesized a set of rationally designed DAG-lactones, which despite their structural simplicity, behave as highly potent PKC ligands capable of displaying comparable, albeit distinct activities to that of the phorbol esters, sometimes even surpassing them in potency. Last year we reported the design of the first isozyme-specific PKC activator capable of inducing the exclusive tranlocation of PKC-alpha to the cellular membrane and PKC-delta to the nuclear membrane. This compound was also able to induce strong apoptosis in human prostate cancer cells, and in the 60-cell line NCI screen potent and selective inhibition of small cell carcinoma and melanoma cells was discovered. Toxicological studies with this compound are underway under the auspices of DTP. B. DNA Methyl Transferase Project (Zebularine). We have demonstrated the ability of zebularine [2(1H)-pyrimidinone riboside] to induce the myogenic phenotype in 10T1/2 cells, which is a phenomenon unique to DNA methylation inhibitors. We also have provided evidence that zebularine can reactivate a silenced p16 gene and demethylate the promoter region in the T24 bladder carcinoma cell line in vitro as well as in tumors grown in BALB/c nu/nu mice. As a result an intensive synthetic program has started aimed at understanding the structure-activity relationship of zebularine and its analogues. Surprisingly, 2'-deoxyzebularine is inactive despite the fact that 2'-deoxyzebularine-5'-triphosphate is suspected of being the key metabolite. Synthesis of several analogues with increased lipophilicity to enhance bioavailability and facilitate formation of 2'-deoxyzebularine-5'-triphosphate is in progress. Protein kinase C isozymes. Chimaerins. Activation/inhibition, Drug design. Zinc finger. DNA methyation, Tumor suppressor genes. Apoptosis.