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Overcoming drug resistance using small molecule activators of protein phosphatase 2A

使用蛋白磷酸酶 2A 小分子激活剂克服耐药性

基本信息

批准号：
10513191
负责人：
JENNIFER D. BLACK
金额：
$ 22.9万
依托单位：
UNIVERSITY OF NEBRASKA MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-08-03 至 2024-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10513191
关键词：
Address Autophagocytosis Biological Breast Cancer Patient CDK2 gene CDK4 gene CRISPR/Cas technology Cancer cell line Cell Cycle Cell Cycle Progression Cell Cycle Proteins Cell Line Cell Proliferation Cell Survival Cells Chemoresistance Clinic Clinical Trials Complex Cyclin D1 Cyclin-Dependent Kinase Inhibitor Cyclins DNA Down-Regulation Drug resistance FDA approved G1 Phase Genetic Genetic Transcription Genotoxic Stress Head and Neck Squamous Cell Carcinoma Holoenzymes Human Immunodeficient Mouse Investigation Knock-out Link Maintenance Malignant Neoplasms Mediating Mitogens Mus Mutation Nature Non-Small-Cell Lung Carcinoma Normal Cell Oncogenic Organoids Patients Pharmaceutical Preparations Pharmacology Pharmacy (field)Phenotype Protein Phosphatase 2A Regulatory Subunit PR53 Protein phosphatase Proteins Proteolysis Publishing Rattus Research Personnel Resistance Role Seminal Signal Transduction Testing Therapeutic Toxic effect Translations Tumor Suppression Tumor Suppressor Proteins Ubiquitin Up-Regulation Xenograft procedure anti-cancer antitumor agent antitumor effect base cancer cell cancer type cell type follow-up genome-wide in vivo Model in vivo evaluation inhibitor mRNA Stability melanoma mouse model multicatalytic endopeptidase complex neoplastic cell novel novel therapeutics nutrient deprivation overexpression preclinical study protein complex resistance mechanism response retinoblastoma tumor suppressor sensor small molecule targeted cancer therapy therapeutic target tumor tumorigenesis ubiquitin-protein ligase uncontrolled cell growth

项目摘要

Uncontrolled cell proliferation resulting from aberrant activity of cell cycle proteins is a hallmark of cancer. Overexpression of the mitogen sensor cyclin D1 is among the most frequent abnormalities in tumors, enhancing the activity of cyclin dependent kinases 4 and 6 (CDK4/6) to drive G1→S phase progression and promote cell survival and chemoresistance. Increased expression of D-type cyclins is required not only for tumorigenesis but also for tumor maintenance and progression. Thus, aberrant cyclin D-CDK4/6 activity represents an actionable target for cancer therapy and D-type cyclin function is among the top therapeutic targets for cancer management. Inhibitors of CDK4/6 activity have shown promise in the clinic and palbociclib, abemaciclib, and ribociclib are FDA-approved for use in patients. Several hundred clinical trials are currently ongoing to evaluate the antitumor effects of these agents in a broad spectrum of cancer types. However, the therapeutic promise of CDK4/6 inhibitors is dampened by inevitable emergence of resistance. Recent seminal studies have identified a novel mechanism of resistance to these agents mediated by deficiency of autophagy and beclin 1 regulator 1 (AMBRA1), an E3 ligase adaptor and master regulator of cyclin D1, D2, and D3 protein stability. Loss or mutation of AMBRA1 is seen in a significant subset of human cancers, in association with poor patient survival. AMBRA1 deficiency promotes the accumulation of D-type cyclins, a hyperproliferative phenotype, and tumorigenesis, while reducing the sensitivity of tumor cells to all three FDA-approved CDK4/6 inhibitors. Evidence that upregulation of D-type cyclins and the formation of non-canonical cyclin D-CDK2 and p27-cyclin D-CDK4 complexes underpins resistance to these agents forms the basis of this proposal. Strategies are proposed to explore the mechanism-driven application of Small Molecule Activators of PP2A (SMAPs) for overcoming resistance to CDK4/6 inhibitors in the context of AMBRA1 deficiency. SMAPs are a novel class of antitumor agents that selectively activate a subset of PP2A holoenzymes for potent tumor suppression in a variety of cancer types. This project builds on our discovery that SMAPs potently downregulate cyclins D1, D2 and D3 in all cell types tested. Importantly, SMAPs act as AMBRA1-independent D-type cyclin ‘degraders,’ promoting rapid proteolysis of these molecules via a proteasome-dependent mechanism that remains functional following loss of AMBRA1. Based on these findings, we hypothesize that combining CDK4/6 inhibitor treatment with a SMAP ‘D-type cyclin degrader’ will enhance antitumor activity and reverse resistance to CDK4/6 inhibitors driven by AMBRA1 deficiency. Proof-of-concept studies will be performed in two Specific Aims: (1) Explore the effects of combining CDK4/6 inhibitors and SMAPS in the context of AMBRA1-deficiency, and (2) Evaluate the effects of SMAP- CDK4/6 inhibitor combinations in tumor models in vivo. Importantly, in addition to addressing consequences of AMBRA1-deficiency, our proof-of-concept findings are anticipated to be broadly applicable to tumors harboring increased levels of D-type cyclins and aberrant CDK activity resulting from other tumor-associated alterations.

细胞周期蛋白异常活动导致的不受控制的细胞增殖是癌症的一个标志。