Autophagy inhibition represents a promising therapeutic approach for the management of various cancers including nonsmall cell lung cancer (NSCLC). We previously reported SBP-7455, a dual inhibitor of unc-51-like kinase 1 (ULK1) and its homologue ULK2 and described its effects on triple-negative breast cancer (TNBC) cells. Herein we report the design, synthesis, and characterization of SBP-5147 and SBP-7501, two new dual ULK1/2 inhibitors that are cytotoxic against NSCLC cells, inhibit autophagic flux in A549 cells, and present greater oral exposure than SBP-7455 at a lower dose. In addition, SBP-5147 effectively modulates autophagy and increases the expression of major histocompatibility complex (MHC) class I in NSCLC cells, which may support the rationale for ULK1/2 inhibition as a strategy to overcome resistance to immunotherapy. Together these data support the use of ULK inhibitors as part of a cancer treatment strategy, either as a single agent or in combination with current therapies.

PDF - 2226KB, Cell viability assays of A) breast cancer cell lines treated with increasing concentrations of the indicated IAP antagonists, B) cancer cells isolated from a patient mammary tumor fragment pretreated with vehicle or 5 μM of the indicated IAP antagonists for 4 h before treatment with TRAIL for a further 20 h, C) MDA-MB-231 cells pretreated with vehicle or 5 μM of the indicated IAP antagonists for 20 h before treatment with TRAIL for a further 20 h and D) MDA-MB-231 cells pretreated with vehicle, 100 μM 3-FC, 5 μM MLS-0390982 or both for 4 h before treatment with TRAIL for a further 20 h. E) Caspase-3/-7 activity assay with NB7 cells expressing empty vector (NB7+Empty Vector), caspase-8 or inactive caspase-8 (C360A) pretreated with 5 μM SBI-0636457 before treatment with 100 ng/mL TRAIL for 4 h. Activity is in relative units.

PDF - 53KB, Legend for Supplementary Figure 1.

Inhibition of autophagy, the major cellular recycling pathway in mammalian cells, is a promising strategy for the treatment of triple-negative breast cancer (TNBC). We previously reported SBI-0206965, a small molecule inhibitor of unc-51-like autophagy activating kinase 1 (ULK1), which is a key regulator of autophagy initiation. Herein, we describe the design, synthesis, and characterization of new dual inhibitors of ULK1 and ULK2 (ULK1/2). One inhibitor, SBP-7455 (compound 26), displayed improved binding affinity for ULK1/2 compared with SBI-0206965, potently inhibited ULK1/2 enzymatic activity in vitro and in cells, reduced the viability of TNBC cells and had oral bioavailability in mice. SBP-7455 inhibited starvation-induced autophagic flux in TNBC cells that were dependent on autophagy for survival and displayed synergistic cytotoxicity with the poly (ADP-ribose) polymerase (PARP) inhibitor olaparib against TNBC cells. These data suggest that combining ULK1/2 and PARP inhibition may have clinical utility for the treatment of TNBC.

The heterogeneous group of diseases collectively termed cancer results not just from aberrant cellular proliferation but also from a lack of accompanying homeostatic cell death. Indeed, cancer cells regularly acquire resistance to programmed cell death, or apoptosis, which not only supports cancer progression but also leads to resistance to therapeutic agents. Thus, various approaches have been undertaken in order to induce apoptosis in tumor cells for therapeutic purposes. Here, we will focus our discussion on agents that directly affect the apoptotic machinery itself rather than on drugs that induce apoptosis in tumor cells indirectly, such as by DNA damage or kinase dependency inhibition. As the roles of the Bcl-2 family have been extensively studied and reviewed recently, we will focus in this review specifically on the inhibitor of apoptosis protein (IAP) family. IAPs are a disparate group of proteins that all contain a baculovirus IAP repeat domain, which is important for the inhibition of apoptosis in some, but not all, family members. We describe each of the family members with respect to their structural and functional similarities and differences and their respective roles in cancer. Finally, we also review the current state of IAPs as targets for anti-cancer therapeutics and discuss the current clinical state of IAP antagonists.

Many tumors become addicted to autophagy for survival, suggesting inhibition of autophagy as a potential broadly applicable cancer therapy. ULK1/Atg1 is the only serine/threonine kinase in the core autophagy pathway and thus represents an excellent drug target. Despite recent advances in the understanding of ULK1 activation by nutrient deprivation, how ULK1 promotes autophagy remains poorly understood. Here, we screened degenerate peptide libraries to deduce the optimal ULK1 substrate motif and discovered 15 phosphorylation sites in core autophagy proteins that were verified as in vivo ULK1 targets. We utilized these ULK1 substrates to perform a cell-based screen to identify and characterize a potent ULK1 small molecule inhibitor. The compound SBI-0206965 is a highly selective ULK1 kinase inhibitor in vitro and suppressed ULK1-mediated phosphorylation events in cells, regulating autophagy and cell survival. SBI-0206965 greatly synergized with mechanistic target of rapamycin (mTOR) inhibitors to kill tumor cells, providing a strong rationale for their combined use in the clinic.

Combination antiretroviral therapy (ART) is able to suppress HIV-1 replication to undetectable levels. However, the persistence of latent viral reservoirs allows for a rebound of viral load upon cessation of therapy. Thus, therapeutic strategies to eradicate the viral latent reservoir are critically needed. Employing a targeted RNAi screen, we identified the ubiquitin ligase BIRC2 (cIAP1), a repressor of the noncanonical NF-κB pathway, as a potent negative regulator of LTR-dependent HIV-1 transcription. Depletion of BIRC2 through treatment with small molecule antagonists known as Smac mimetics enhanced HIV-1 transcription, leading to a reversal of latency in a JLat latency model system. Critically, treatment of resting CD4+ T cells isolated from ART-suppressed patients with the histone deacetylase inhibitor (HDACi) panobinostat together with Smac mimetics resulted in synergistic activation of the latent reservoir. These data implicate Smac mimetics as useful agents for shock-and-kill strategies to eliminate the latent HIV reservoir.

Combination antiretroviral therapy (ART) is able to suppress HIV-1 replication to undetectable levels. However, the persistence of latent viral reservoirs allows for a rebound of viral load upon cessation of therapy. Thus, therapeutic strategies to eradicate the viral latent reservoir are critically needed. Employing a targeted RNAi screen, we identified the ubiquitin ligase BIRC2 (cIAP1), a repressor of the noncanonical NF- κ B pathway, as a potent negative regulator of LTR-dependent HIV-1 transcription. Depletion of BIRC2 through treatment with small molecule antagonists known as Smac mimetics enhanced HIV-1 transcription, leading to a reversal of latency in a JLat latency model system. Critically, treatment of resting CD4+ T cells isolated from ART-suppressed patients with the histone deacetylase inhibitor (HDACi) panobinostat together with Smac mimetics resulted in synergistic activation of the latent reservoir. These data implicate Smac mimetics as useful agents for shock-and-kill strategies to eliminate the latent HIV reservoir. we B as as a therapeutic target for the reversal of latency. Small molecule antagonists of BIRC2, in combination with HDAC inhibitors, activated latent proviruses in both cell line-based models of latency and in primary CD4+ T cells isolated from ART-suppressed HIV-1-infected patients. The results of this study indicate that the pharmacological activation of the noncanonical NF- κ B pathway can be used as a component of a combinatorial regimen to reactivate latent HIV-1, while potentially limiting toxicity risks associated with systemic activation of NF- κ B signaling by PKC agonists.

Abstract TNF-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent because it shows apoptosis-inducing activity in transformed, but not in normal, cells. As with most anticancer agents, however, its clinical use is restricted by either inherent or acquired resistance by cancer cells. We demonstrate here that small-molecule SMAC mimetics that antagonize the inhibitor of apoptosis proteins (IAP) potently sensitize previously resistant human cancer cell lines, but not normal cells, to TRAIL-induced apoptosis, and that they do so in a caspase-8–dependent manner. We further show that the compounds have no cytotoxicity as single agents. Also, we demonstrate that several IAP family members likely participate in the modulation of cellular sensitivity to TRAIL. Finally, we note that the compounds that sensitize cancer cells to TRAIL are the most efficacious in binding to X-linked IAP, and in inducing cellular-IAP (cIAP)-1 and cIAP-2 degradation. Our studies thus describe valuable compounds that allow elucidation of the signaling events occurring in TRAIL resistance, and demonstrate that these agents act as potent TRAIL-sensitizing agents in a variety of cancer cell lines. Mol Cancer Ther; 13(1); 5–15. ©2013 AACR.

A practical and efficient method for the synthesis of substituted 2-aminopyridines from pyridine N-oxides is reported. Yields of purified, isolated products of up to 84% are observed for the one-pot, two-step process. The reaction involves an in situ deprotection of an isolable N-formylaminopyridine intermediate and facilitates the synthesis of 2-aminopyridines for which other methods fail.

Abstract The standard of care for ovarian cancer patients is carboplatin and paclitaxel. While many tumors initially respond to these drugs, patients often relapse with resistant disease. One of the mechanisms implicated in this development of resistance is evasion of apoptosis. Exploiting alternative death pathways, including necroptosis, is one strategy to treat such recurrent disease. Overexpressed in many cancers, inhibitor of apoptosis proteins (IAPs) represent one family of promising targets. Treatment of cells with an IAP antagonist can activate apoptosis or, if caspases are blocked, necroptosis. Among a panel of ovarian cancer cell lines screened for sensitivity to an IAP antagonist in combination with a pan-caspase inhibitor, only one (OVCAR3) was found to be sensitive, but this sensitivity was also exhibited by serous ovarian cancer cells isolated from patients. Combination treatment induces the formation of a p62-associated necrosome (RIPK1/RIPK3/FADD/caspase-8), and death can be rescued with inhibitors of RIPK1 and MLKL, two key proteins in the necroptosis pathway. All sensitive cell lines, but no resistant lines, express RIPK3 protein, and data from knockdown and ectopic expression studies demonstrate the dependency of cell death on kinase-active RIPK3, as well as caspase-8. Studies using a TNFα neutralizing antibody suggest that the combination elicits autocrine production of TNFα, which likely, in turn, activates the extrinsic death pathway in these cells. In conclusion, these findings illustrate that necroptosis can be induced in RIPK3-expressing ovarian cancer cells and indicate that in vivo studies are warranted. Citation Format: Katelyn E. McCabe, Karl Bacos, Dan Lu, Joe R. Delaney, Mitchell Vamos, Nicholas D. P. Cosford, Dwayne G. Stupack. Induction of necroptosis in ovarian cancer cells as a therapeutic strategy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1340. doi:10.1158/1538-7445.AM2014-1340

Ovarian cancer patients are typically treated with carboplatin and paclitaxel, but suffer a high rate of relapse with recalcitrant disease. This challenge has fostered the development of novel approaches to treatment, including antagonists of the ‘inhibitor of apoptosis proteins’ (IAPs), also called SMAC mimetics, as apoptosis-inducing agents whose action is opposed by caspase inhibitors. Surprisingly, IAP antagonist plus caspase inhibitor (IZ) treatment selectively induced a tumor necrosis factor- α (TNF α )-dependent death among several apoptosis-resistant cell lines and patient xenografts. The induction of necroptosis was common in ovarian cancer, with expression of catalytically active receptor-interacting protein kinase-3 (RIPK3) necessary for death, and in fact sufficient to compromise survival of RIPK3-negative, necroptosis-resistant ovarian cancer cells. The formation of a necrosome-like complex with a second critical effector, receptor-interacting serine–threonine kinase-1 (RIPK1), was observed. RIPK1, RIPK3 and TNF α were required for the induction of death, as agents that inhibit the function of any of these targets prevented cell death. Abundant RIPK3 transcript is common in serous ovarian cancers, suggesting that further evaluation and targeting of this RIPK3-dependent pathway may be of clinical benefit.

ChemInformVolume 45, Issue 34 Heterocyclic Compounds ChemInform Abstract: 2-Aminopyridines via Reaction of Pyridine N-Oxides and Activated Isocyanides. Mitchell Vamos, Mitchell Vamos Conrad Prebys Cent. Chem. Genom., Sanford-Burnham Med. Res. Inst., La Jolla, CA 92037, USASearch for more papers by this authorNicholas D. P. Cosford, Nicholas D. P. Cosford Conrad Prebys Cent. Chem. Genom., Sanford-Burnham Med. Res. Inst., La Jolla, CA 92037, USASearch for more papers by this author Mitchell Vamos, Mitchell Vamos Conrad Prebys Cent. Chem. Genom., Sanford-Burnham Med. Res. Inst., La Jolla, CA 92037, USASearch for more papers by this authorNicholas D. P. Cosford, Nicholas D. P. Cosford Conrad Prebys Cent. Chem. Genom., Sanford-Burnham Med. Res. Inst., La Jolla, CA 92037, USASearch for more papers by this author First published: 07 August 2014 https://doi.org/10.1002/chin.201434176Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume45, Issue34August 26, 2014 RelatedInformation

A series of novel, potent antagonists of the inhibitor of apoptosis proteins (IAPs) were synthesized in a highly convergent and rapid fashion (≤6 steps) using the Ugi four-component reaction as the key step, thus enabling rapid optimization of binding potency. These IAP antagonists compete with caspases 3, 7, and 9 for inhibition by X chromosome-linked IAP (XIAP) and bind strongly (nanomolar binding constants) to several crucial members of the IAP family of cancer pro-survival proteins to promote apoptosis, with a particularly unique selectivity for melanoma IAP (ML-IAP). Experiments in cell culture revealed powerful cancer cell growth inhibitory activity in multiple (breast, ovarian, and prostate) cell lines with single agent toxicity at low nanomolar levels against SKOV-3 human ovarian carcinoma cells. Administration of the compounds to human foreskin fibroblast cells revealed no general toxicity to normal cells. Furthermore, computational modeling was performed, revealing key contacts between the IAP proteins and antagonists, suggesting a structural basis for the observed potency.

Herein we report the discovery and SAR of a novel metabotropic glutamate receptor 3 (mGlu(3)) NAM probe (ML289) with 15-fold selectivity versus mGlu(2). The mGlu(3) NAM was discovered via a 'molecular switch' from a closely related, potent mGlu(5) positive allosteric modulator (PAM), VU0092273. This NAM (VU0463597, ML289) displays an IC(50) value of 0.66 μM and is inactive against mGlu(5).

The synthesis of a propellane derivative of salinosporamide A having increased stability under physiological-like conditions is reported. The synthesis took advantage of a substrate-controlled stereoselective Ugi 4-center 3-component reaction to construct the required syn-bicyclic pyroglutamic acid framework.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.