Mechanism of Action of TOP2-Directed Anticancer Drugs

TOP2靶向抗癌药物的作用机制

• 批准号: 8129544
• 负责人: LEROY F LIU
• 金额: $ 29.5万
• 依托单位: UNIV OF MED/DENT NJ-R W JOHNSON MED SCH
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-03-10 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8129544
• 关键词: Adverse effects; Animal Model; Antineoplastic Agents; Apoptotic; Binding; Bortezomib; Caspase Inhibitor; Cell Culture Techniques; Cell Cycle; Cells; Chimeric Proteins; Chromosomal translocation; Chromosome Condensation; Clinic; Complex; DNA; DNA Double Strand Break; DNA Sequence Rearrangement; DNA biosynthesis; DNA-Directed RNA Polymerase; Development; Down-Regulation; Doxorubicin; Drug Delivery Systems; Equilibrium; Etoposide; Event; Exhibits; Foundations; Gene Expression; Gene Fusion; Genes; Genetic Transcription; Goals; Health; Hematopoietic; Human; Isoenzymes; Knockout Mice; Lead; Link; MLL gene; Mediating; Mitoxantrone; Molecular; Molecular Models; Mus; Myeloid Progenitor Cells; Nonhomologous DNA End Joining; Pathway interactions; Pharmaceutical Preparations; Play; Proliferating; Proteasome Inhibition; Proteins; Role; Skin; Skin Carcinogenesis; Stem cells; TOP2A gene; Testing; Therapy-Related Acute Myeloid Leukemia; Topoisomerase II; Ubiquitin; base; cancer therapy; improved; molecular modeling; mouse model; multicatalytic endopeptidase complex; neoplastic cell; novel; nuclease; overexpression; promoter; segregation; small hairpin RNA; stem

DESCRIPTION (provided by applicant): The long-term goal of this application is to understand the mechanism of action of topoisomerase II (Top2)-targeting drugs. Top2-targeting drugs such as etoposide (VP-16), doxorubicin and mitoxantrone are among the most effective and widely used anticancer drugs in the clinic. Despite their impressive antitumor activities, Top2-targeting drugs are known to cause serious side effects such as t-AML (therapy-related acute myeloid leukemia). Etoposide-induced t-AML is frequently associated with balanced translocations of the mixed lineage leukemia gene (MLL) and many MLL partner genes, resulting in the expression of MLL fusion proteins. There has been substantial evidence that these translocations are primarily the consequence of etoposide-induced DNA cleavage(s) within the breakpoint cluster region (BCR) of the human MLL gene. Both Top2 and CAD (an apoptotic nuclease) have been shown to be involved in etoposide-induced DNA cleavage(s) within the MLL BCR. Our recent studies have suggested that the two Top2 isozymes, Top21 and Top22 may play different roles in the antitumor activity and side effects of Top2-targeting drugs. Top21 targeting has been suggested to contribute to the antitumor activity of etoposide while the role of Top22 targeting by etoposide is unclear. Our preliminary studies have demonstrated that Top22 targeting by etoposide triggers transcription-dependent, proteasome-mediated degradation of Top22 (Top22 down-regulation), resulting in the exposure of Top22-concealed DNA double-strand breaks. In addition, Top22 is primarily responsible for etoposide-induced DNA sequence rearrangements and skin carcinogenesis. In the current proposal, we plan to test the hypothesis that the Top22 isozyme is primarily responsible for etoposide-induced MLL translocations and t-AML. In addition, we plan to elucidate the molecular mechanism for etoposide-induced MLL translocations by determining the roles of Top22 isozyme, proteasome and CAD using both cell culture and animal models. The specific aims are (1) to determine the role of the Top22 isozyme in etoposide-induced MLL translocations and t-AML, (2) to determine whether proteasome and the apoptotic nuclease CAD are involved in etoposide-induced MLL translocations and t-AML, and (3) to elucidate the molecular mechanism for etoposide-induced Top22 down-regulation. Successful completion of the proposed studies will not only advance our understanding of the molecular basis for Top2 drug-induced t-AML but also provide a theoretical foundation for developing Top2 isozyme-specific anticancer drugs, as well as new strategies, for more efficacious Top2-based cancer therapy. PUBLIC HEALTH RELEVANCE: The successful demonstration of the role of Top22 in MLL translocations will provide the necessary theoretical foundation for developing Top21 isozyme-specific anticancer drugs which are expected to exhibit reduced toxic side effects (e.g. t-AML). In addition, elucidation of the molecular basis for etoposide-induced MLL translocations can also lead to development of new strategies for improving current Top2-based therapy. For example, ICRF-187 (for specific down-regulation of Top22), bortezomib (for inhibition of proteasome) or caspase inhibitors (for blocking CAD activation) could be employed to reduce the toxic side effects associated with current Top2-based therapy.

描述（由申请人提供）：本申请的长期目标是了解拓扑异构酶II（TOP2）靶向药物的作用机理。前2个靶向药物，例如依托泊苷（VP-16），阿霉素和米托甘坦酮是诊所中最有效且最广泛使用的抗癌药物之一。尽管具有令人印象深刻的抗肿瘤活性，但众所周知，靶向前2个靶向药物会引起严重的副作用，例如T-AML（与治疗相关的急性髓样白血病）。依托泊苷诱导的T-AML经常与混合谱系白血病基因（MLL）和许多MLL伴侣基因的平衡易位有关，从而导致MLL融合蛋白的表达。有大量证据表明，这些易位主要是依托泊苷诱导的DNA裂解（S）在人类MLL基因的断点群集区域（BCR）中的结果。 TOP2和CAD（凋亡核酸酶）均已证明与MLL BCR内的依托泊苷诱导的DNA裂解有关。我们最近的研究表明，TOP2同工酶TOP21和TOP22在抗肿瘤活性和TOP2靶向药物的副作用中可能起不同的作用。 TOP21的靶向靶向有助于依托泊苷的抗肿瘤活性，而依托泊苷的TOP22靶向作用尚不清楚。我们的初步研究表明，依托泊苷靶向TOP22会触发转录依赖性的，蛋白酶体介导的TOP22（TOP22下调）的降解，从而导致TOP22连续的DNA DNA双重股突破。此外，TOP22主要负责依托泊苷诱导的DNA序列重排和皮肤致癌作用。在当前的建议中，我们计划检验TOP22同工酶主要负责依托泊苷诱导的MLL易位和T-AML的假设。此外，我们计划通过使用细胞培养和动物模型来确定TOP22同工酶，蛋白酶体和CAD的作用来阐明依托泊苷诱导的MLL易位的分子机制。具体目的是（1）确定TOP22同工酶在依托波胺诱导的MLL易位和T-AML中的作用，（2），以确定蛋白酶体和凋亡核酸酶CAD是否参与依托泊苷诱导的MLL易感和T-AML和T-AML，以及（3），以及（3）以阐明了eToposillim powrop222222222222222222222。成功完成拟议的研究不仅会提高我们对TOP2药物诱导的T-AML的分子基础的理解，而且还为开发TOP2同工酶特异性抗癌药物以及新策略提供了理论基础，以进行更有效的TOP2基于TOP2的癌症治疗。公共卫生相关性：TOP22在MLL易位中的作用的成功证明将为开发TOP21同工酶特异性抗癌药物提供必要的理论基础，这些药物有望表现出降低的毒性副作用（例如T-AML）。此外，阐明依托泊苷诱导的MLL易位的分子基础也可能导致发展新的策略来改善当前的基于TOP2的治疗。例如，可以使用ICRF-187（用于TOP22的特定下调），硼替佐米（用于抑制蛋白酶体）或caspase抑制剂（用于阻断CAD激活）来减少与当前基于TOP2的治疗相关的毒性副作用。