Apoptosis is an intrinsic cell death program that plays critical roles in tissue homeostasis, especially in organs where high rates of daily cell production are offset by rapid cell turnover. The ...hematopoietic system provides numerous examples attesting to the importance of cell death mechanisms for achieving homeostatic control. Much has been learned about the mechanisms of apoptosis of lymphoid and hematopoietic cells since the seminal observation in 1980 that glucocorticoids induce DNA fragmentation and apoptosis of thymocytes and the demonstration in 1990 that depriving colony-stimulating factors from factor-dependent hematopoietic cells causes programmed cell death. From an understanding of the core components of the apoptosis machinery at the molecular and structural levels, many potential new therapies for leukemia and lymphoma are emerging. In this review, we introduce some of the drug discovery targets thus far identified within the core apoptotic machinery and describe some of the progress to date toward translating our growing knowledge about these targets into new therapies for cancer and leukemia.
We have recently reported on the use of aryl-fluorosulfates in designing water- and plasma-stable agents that covalently target Lys, Tyr, or His residues in the BIR3 domain of the inhibitor of the ...apoptosis protein (IAP) family. Here, we report further structural, cellular, and pharmacological characterizations of this agent, including the high-resolution structure of the complex between the Lys-covalent agent and its target, the BIR3 domain of X-linked IAP (XIAP). We also compared the cellular efficacy of the agent in two-dimensional (2D) and three-dimensional (3D) cell cultures, side by side with the clinical candidate reversible IAP inhibitor LCL161. Finally, in vivo pharmacokinetic studies indicated that the agent was long-lived and orally bioavailable. Collectively our data further corroborate that aryl-fluorosulfates, when incorporated correctly in a ligand, can result in Lys-covalent agents with pharmacodynamic and pharmacokinetic properties that warrant their use in the design of pharmacological probes or even therapeutics.
EphA2 overexpression has been associated with metastasis in multiple cancer types, including melanomas and ovarian, prostate, lung, and breast cancers. We have recently proposed the development of ...peptide–drug conjugates (PDCs) using agonistic EphA2-targeting agents, such as the YSA peptide or its optimized version, 123B9. Although our studies indicated that YSA– and 123B9–drug conjugates can selectively deliver cytotoxic drugs to cancer cells in vivo, the relatively low cellular agonistic activities (i.e., the high micromolar concentrations required) of the agents toward the EphA2 receptor remained a limiting factor to the further development of these PDCs in the clinic. Here, we report that a dimeric version of 123B9 can induce receptor activation at nanomolar concentrations. Furthermore, we demonstrated that the conjugation of dimeric 123B9 with paclitaxel is very effective at targeting circulating tumor cells and inhibiting lung metastasis in breast-cancer models. These studies represent an important step toward the development of effective EphA2-targeting PDCs.
Modulating disease-relevant protein–protein interactions (PPIs) using pharmacological tools is a critical step toward the design of novel therapeutic strategies. Over the years, however, targeting ...PPIs has proven a very challenging task owing to the large interfacial areas. Our recent efforts identified possible novel routes for the design of potent and selective inhibitors of PPIs using a structure-based design of covalent inhibitors targeting Lys residues. In this present study, we report on the design, synthesis, and characterizations of the first Lys-covalent BH3 peptide that has a remarkable affinity and selectivity for hMcl-1 over the closely related hBfl-1 protein. Our structural studies, aided by X-ray crystallography, provide atomic-level details of the inhibitor interactions that can be used to further translate these discoveries into novel generation, Lys-covalent pro-apoptotic agents.
Glioblastoma multiforme (GBM) is an intractable tumor despite therapeutic advances, principally because of its invasive properties. Radiation is a staple in therapeutic regimens, although cells ...surviving radiation can become more aggressive and invasive. Subtraction hybridization identified melanoma differentiation-associated gene 9 MDA-9/Syntenin; syndecan-binding protein (SDCBP) as a differentially regulated gene associated with aggressive cancer phenotypes in melanoma. MDA-9/Syntenin, a highly conserved double-PDZ domain-containing scaffolding protein, is robustly expressed in human-derived GBM cell lines and patient samples, with expression increasing with tumor grade and correlating with shorter survival times and poorer response to radiotherapy. Knockdown of MDA-9/Syntenin sensitizes GBM cells to radiation, reducing postradiation invasion gains. Radiation induces Src and EGFRvIII signaling, which is abrogated through MDA-9/Syntenin down-regulation. A specific inhibitor of MDA-9/Syntenin activity, PDZ1i (113B7), identified through NMR-guided fragment-based drug design, inhibited MDA-9/Syntenin binding to EGFRvIII, which increased following radiation. Both genetic (shmda-9) and pharmacological (PDZ1i) targeting of MDA-9/Syntenin reduced invasion gains in GBM cells following radiation. Although not affecting normal astrocyte survival when combined with radiation, PDZ1i radiosensitized GBM cells. PDZ1i inhibited crucial GBM signaling involving FAK and mutant EGFR, EGFRvIII, and abrogated gains in secreted proteases, MMP-2 and MMP-9, following radiation. In an in vivo glioma model, PDZ1i resulted in smaller, less invasive tumors and enhanced survival. When combined with radiation, survival gains exceeded radiotherapy alone. MDA-9/Syntenin (SDCBP) provides a direct target for therapy of aggressive cancers such as GBM, and defined small-molecule inhibitors such as PDZ1i hold promise to advance targeted brain cancer therapy.
Targeting the Bcl-2 family for cancer therapy Thomas, Shibu; Quinn, Bridget A; Das, Swadesh K ...
Expert opinion on therapeutic targets,
01/2013, Letnik:
17, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Introduction:
Programmed cell death is well-orchestrated process regulated by multiple pro-apoptotic and anti-apoptotic genes, particularly those of the Bcl-2 gene family. These genes are well ...documented in cancer with aberrant expression being strongly associated with resistance to chemotherapy and radiation.
Areas covered:
This review focuses on the resistance induced by the Bcl-2 family of anti-apoptotic proteins and current therapeutic interventions currently in preclinical or clinical trials that target this pathway. Major resistance mechanisms that are regulated by Bcl-2 family proteins and potential strategies to circumvent resistance are also examined. Although antisense and gene therapy strategies are used to nullify Bcl-2 family proteins, recent approaches use small molecule inhibitors (SMIs) and peptides. Structural similarity of the Bcl-2 family of proteins greatly favors development of inhibitors that target the BH3 domain, called BH3 mimetics.
Expert opinion:
Strategies to specifically identify and inhibit critical determinants that promote therapy resistance and tumor progression represent viable approaches for developing effective cancer therapies. From a clinical perspective, pretreatment with novel, potent Bcl-2 inhibitors either alone or in combination with conventional therapies hold significant promise for providing beneficial clinical outcomes. Identifying SMIs with broader and higher affinities for inhibiting all of the Bcl-2 pro-survival proteins will facilitate development of superior cancer therapies.
Processing of certain viral proteins and bacterial toxins by host serine proteases is a frequent and critical step in virulence. The coronavirus spike glycoprotein contains three (S1, S2, and S2') ...cleavage sites that are processed by human host proteases. The exact nature of these cleavage sites, and their respective processing proteases, can determine whether the virus can cross species and the level of pathogenicity. Recent comparisons of the genomes of the highly pathogenic SARS-CoV2 and MERS-CoV, with less pathogenic strains (e.g., Bat-RaTG13, the bat homologue of SARS-CoV2) identified possible mutations in the receptor binding domain and in the S1 and S2' cleavage sites of their spike glycoprotein. However, there remains some confusion on the relative roles of the possible serine proteases involved for priming. Using anthrax toxin as a model system, we show that in vivo inhibition of priming by pan-active serine protease inhibitors can be effective at suppressing toxicity. Hence, our studies should encourage further efforts in developing either pan-serine protease inhibitors or inhibitor cocktails to target SARS-CoV2 and potentially ward off future pandemics that could develop because of additional mutations in the S-protein priming sequence in coronaviruses.
Abstract
Oncology drugs osimertinib, ibrutinib, neratinib, and afatinib have all been approved in very recent years by the FDA, and all target a cysteine that is present in proximity to the binding ...site of their respective targets. More recently, Amgen reported on AMG 510 as a first-in-class investigational drug designed to selectively and irreversibly target the KRAS G12C protein. These drugs rely on acrylamides moieties strategically incorporated in their chemical structures to selectively and efficiently react with binding site cysteine residues. Obviously, the approach is limited to drug targets that present a cysteine residue in proximity to the binding site, which often is not the case. This druggable target space for covalent drugs is called the Cysteinome. My laboratory has been developing and applying novel strategies aimed at deriving potent, selective, cell-permeable, and efficacious covalent therapeutics by designing agents that can selectively react with lysine residues (1,2). The approach relies on introducing stable aryl-fluorosulfates or sulfonyl-fluorides in drug leads to selectively and efficiently react with lysine residues. Because lysines are more ubiquitously found within the binding pocket of the target oncogenes, the approach defines a much larger target space for covalent drugs: the Lysinome. In addition, I will demonstrate that the approach is amenable also to tackle difficult targets such as those involving protein-protein interactions (PPIs). Hence, our work widens the available target space beyond cysteine and also allows the development of novel drug candidates against PPIs, which represent an untapped large class of therapeutic targets in oncology. Examples will include potent and selective Lys-covalent agents targeting antiapoptotic proteins in the IAP and Bcl-2 families of proteins, including particularly exciting, yet to be published results.
References: 1. Gambini L, Baggio C, Udompholkul P, Jossart J, Salem AF, Perry JJP, Pellecchia M. Covalent inhibitors of protein-protein interactions targeting lysine, tyrosine, or histidine residues. J Med Chem 2019;13;62(11):5616-27. 2. Baggio C, Udompholkul P, Gambini L, Salem AF, Jossart J, Perry JJP, Pellecchia M. Aryl-fluorosulfate-based lysine covalent pan-inhibitors of apoptosis protein (IAP) antagonists with cellular efficacy. J Med Chem 2019;Oct. 8. doi: 10.1021/acs.jmedchem.9b01108.
Citation Format: Maurizio Pellecchia. Targeting difficult targets with lysine-covalent ligands: Expanding the druggable space for covalent drugs abstract. In: Proceedings of the AACR Special Conference on Advancing Precision Medicine Drug Development: Incorporation of Real-World Data and Other Novel Strategies; Jan 9-12, 2020; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_1):Abstract nr 20.
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