Through screening by NMR spectroscopy, we discovered a novel scaffold (DPQ: 6,7-dimethoxy-2-(1-piperazinyl)-4-quinazolinamine) that binds specifically to the influenza A virus RNA promoter. The ...solution structure of the RNA-DPQ complex reported here demonstrates that the internal loop is the binding site of DPQ. The scaffold exhibits antiviral activity against influenza viruses.
Paneth cells are a highly specialized population of intestinal epithelial cells located in the crypt adjacent to Lgr5+ stem cells, from which they differentiate through a process that requires ...downregulation of the Notch pathway. Their ability to store and release antimicrobial peptides protects the host from intestinal pathogens and controls intestinal inflammation. Here, we show that PKCλ/ι is required for Paneth cell differentiation at the level of Atoh1 and Gfi1, through the control of EZH2 stability by direct phosphorylation. The selective inactivation of PKCλ/ι in epithelial cells results in the loss of mature Paneth cells, increased apoptosis and inflammation, and enhanced tumorigenesis. Importantly, PKCλ/ι expression in human Paneth cells decreases with progression of Crohn’s disease. Kaplan-Meier survival analysis of colorectal cancer (CRC) patients revealed that low PRKCI levels correlated with significantly worse patient survival rates. Therefore, PKCλ/ι is a negative regulator of intestinal inflammation and cancer through its role in Paneth cell homeostasis.
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•PKCλ/ι is required for Paneth cell differentiation•PKCλ/ι reduces EZH2 stability and promotes Atoh1 and Gfi1 expression•PKCλ/ι induces intestinal epithelial cell survival through the repression of JNK•PKCλ/ι loss enhances intestinal inflammation and cancer
Nakanishi et al. demonstrate that the atypical PKCλ/ι is lost in the intestinal epithelium of Crohn’s disease patients, and its genetic inactivation in mice results in defective Paneth cell differentiation, enhanced JNK activity, and apoptosis in the intestinal epithelium, which leads to increased intestinal inflammation and tumorigenesis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Oral and oropharyngeal cancers are the sixth most common cancers worldwide. Despite intensive investigation, oral squamous cell carcinomas (OSCC) represent a clinical challenge resulting in ...significant morbidity and mortality. Resistance to cell death is common in OSCC and is often mediated by the Bcl-2 family proteins. Among all anti-apoptotic Bcl-2 family members, Mcl-1 functions as a major survival factor, particularly in solid cancers. Despite the confirmed importance of Mcl-1 in several neoplasms, the role of Mcl-1 in OSCC survival has yet to be explored. In this study, we found that knocking down Mcl-1 sensitized OSCC cells to ABT-737, which binds to Bcl-2/Bcl-xL but not Mcl-1. We report for the first time that a BH3 mimetic, Sabutoclax, which functions as an inhibitor of all anti-apoptotic Bcl-2 proteins, induced cancer-specific cell death in an Mcl-1-dependent manner through both apoptosis and toxic mitophagy. In vivo studies demonstrated that Sabutoclax alone decreased tumor growth in a carcinogen-induced tongue OSCC mouse model. In a combination regimen, Sabutoclax and COX-2 inhibitor, Celecoxib, synergistically inhibited the growth of OSCC in vitro and also significantly reduced OSCC tumor growth in vivo. Overall, these results identify Mcl-1 as a therapeutic prospective target in OSCC.
Overexpression of antiapoptotic members of the Bcl-2 family proteins, such as Bcl-xL and Mfl-1, has been shown to be involved in resistance to chemotherapeutic drugs in many forms of cancers. Recent ...efforts from the Abbott Laboratories resulted in the development of the acylsulfonamide compound and clinical candidate that targets selectively Bcl-2, Bcl-xL, and Bcl-w while it is not active against Mcl-1 and Bfl-1. However, early clinical and preclinical studies suggest that pan-Bcl-2 antagonists, targeting simultaneously Mcl-1, Bcl-xL, and possibly all other four antiapoptotic Bcl-2 proteins, may result in more efficacious drugs. Here, following an NMR fragment-based approach, SAR by ILOEs, we report on compounds that exhibit nanomolar affinities for both Bcl-xL and Mcl-1 in vitro. We believe that these molecules can be used as useful starting point for the development of novel Bcl-2 antagonists, in particular targeting Mcl-1.
Abstract Owing to the high levels of antiapoptotic B-cell lymphoma 2 (BCL-2) family members observed in several cancers, there has been a major effort to develop inhibitors of the BCL2-family as ...chemotherapeutic agents. Of the different members in the BCL-2 family, myeloid cell leukemia sequence 1 (MCL-1) is commonly amplified in human tumors and is associated with their relapse and chemoresistance. As a result, specific inhibitors of MCL-1 are being designed to treat resistant tumors. However, there is increasing evidence for other nonapoptotic roles of the BCL-2 family, ranging from ionic homeostasis and autophagy to the regulation of fission-fusion dynamics in subcellular organelles, including the endoplasmic reticulum and mitochondria. In this study, we characterize the specificity of two novel putative MCL-1 inhibitors, BI97C1 (Sabutoclax) and BI112D1, in inducing apoptosis in a BAX/BAK-dependent manner and in an MCL-1-dependent system. In addition to their being proapoptotic, these inhibitors also cause enhanced mitochondrial fragmentation that accompanies a time-dependent loss of optic atrophy 1 (OPA1), suggesting an impairment of mitochondrial fusion. This mitochondrial fragmentation occurs independently of dynamin-related protein 1 (DRP1)-mediated fission activity and, unlike most apoptotic stimuli, occurs upstream of and/or independent of BAX, BAK, and other BH3-only proteins. Furthermore, this mitochondrial fragmentation occurred rapidly and preceded other hallmarks of apoptosis, including the loss in mitochondrial membrane potential and the release of cytochrome c . Although such mitochondrial fragmentation did not deplete total cellular adenosine triphosphate (ATP) or alter other mitochondrial complexes, there was significant accumulation of reactive oxygen species.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Targeting Influenza A Virus RNA Promoter Bottini, Angel; De, Surya K.; Wu, Bainan ...
Chemical biology & drug design,
October 2015, Volume:
86, Issue:
4
Journal Article
Peer reviewed
Open access
The emergence of drug‐resistant strains of influenza virus makes exploring new classes of inhibitors that target universally conserved viral targets a highly important goal. The influenza A viral ...genome is made up of eight single‐stranded RNA‐negative segments. The RNA promoter, consisting of the conserved sequences at the 3′ and 5′ end of each RNA genomic segment, is universally conserved among influenza A virus strains and in all segments. Previously, we reported on the identification and NMR structure of DPQ (6,7‐dimethoxy‐2‐(1‐piperazinyl)‐4‐quinazolinamine) (compound 1) in complex with the RNA promoter. Here, we report on additional screening and SAR studies with compound 1, including ex vivo anti‐influenza activity assays, resulted in improved cellular activity against influenza A virus in the micromolar range.
The influenza A RNA promoter is universally conserved among influenza A virus strains, making it potentially an ideal drug target for novel antiviral agents. Using an NMR‐based approach, we report on the characterization and initial SAR studies of RNA binding compounds, including ex vivo anti‐influenza activity assays.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Identification of a Novel Mcl-1 Protein Binding Motif Placzek, William J.; Sturlese, Mattia; Wu, Bainan ...
Journal of biological chemistry/The Journal of biological chemistry,
11/2011, Volume:
286, Issue:
46
Journal Article
Peer reviewed
Open access
Recent characterization of Mcl-1 as the primary anti-apoptotic Bcl-2 family member expressed in solid tumors, coupled with its ability to enable therapeutic resistance, has provided the impetus for ...further study into how Mcl-1 is involved in apoptosis signaling. Here, we employ Sabutoclax, a potent and effective Mcl-1 antagonist, as a competing agent to screen a randomized 12-residue phage display library for peptides that bind strongly to the Bcl-2 homology 3 (BH3) binding groove of Mcl-1. Although the screen identified a number of α-helical peptides with canonical BH3 domain sequences, it also isolated a pair of unique peptide sequences. These sequences exhibit a reverse organization of conserved hydrophobic and acidic residues when compared with canonical BH3 sequences, and we therefore refer to them as reverse BH3 (rBH3) peptides. Furthermore, studies of the rBH3 peptides using NMR spectroscopy, fluorescence polarization displacement assays, and alanine scanning data all suggest that they bind to the BH3 binding groove of Mcl-1 selectively over Bcl-xL. A search for proteins containing the rBH3 motif has identified a number of interesting Mcl-1 protein partners, some of which have previously been associated with apoptosis regulation involving Mcl-1. These findings provide insights into the development of more specific Mcl-1 antagonists and open the way to the identification of a previously unknown family of apoptosis-regulating and Mcl-1 interacting proteins.
Background: We sought to identify novel peptide sequences that interact at the BH3 binding groove of Mcl-1.
Results: We identified a peptide that binds to Mcl-1 in a reverse orientation compared with canonical BH3 peptides.
Conclusion: The peptide binds to Mcl-1 selectively over other Bcl-2 proteins.
Significance: The novel sequence is useful in identifying Mcl-1 binding partners and for developing possible therapeutics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We report comprehensive structure−activity relationship studies on a novel series of c-Jun N-terminal kinase (JNK) inhibitors. The compounds are substrate competitive inhibitors that bind to the ...docking site of the kinase. The reported medicinal chemistry and structure-based optimizations studies resulted in the discovery of selective and potent thiadiazole JNK inhibitors that display promising in vivo activity in mouse models of insulin insensitivity.
Summary
The E3 ubiquitin ligase Siah2 has been implicated in the regulation of the hypoxia response, as well as in the control of Ras, JNK/p38/NF‐κB signaling pathways. Both Ras/mitogen‐activated ...protein kinase (MAPK) and hypoxia pathways are important for melanoma development and progression, pointing to the possible use of Siah2 as target for treatment of this tumor type. In the present study, we have established a high‐throughput electro‐chemiluninescent‐based assay in order to screen and identify inhibitors of Siah2 ubiquitin ligase activity. Of 1840 compounds screened, we identified and characterized menadione (MEN) as a specific inhibitor of Siah2 ligase activity. MEN attenuated Siah2 self‐ubiquitination, and increased expression of its substrates PHD3 and Sprouty2, with concomitant decrease in levels of HIF‐1α and pERK, the respective downstream effectors. MEN treatment no longer affected PHD3 or Sprouty2 in Siah‐KO cells, pointing to its Siah‐dependent effects. Further, MEN inhibition of Siah2 was not attenuated by free radical scavenger, suggesting it is ROS‐independent. Significantly, growth of xenograft melanoma tumors was inhibited following the administration of MEN or its derivative. These findings reveal an efficient platform for the identification of Siah inhibitors while identifying and characterizing MEN as Siah inhibitor that attenuates hypoxia and MAPK signaling, and inhibits melanoma tumorigenesis.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
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