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Even though many GyrB and ParE inhibitors have been reported in the literature, few possess activity against Gram-negative bacteria. This is primarily due to limited permeability across Gram-negative bacterial membrane as well as bacterial efflux mechanisms. Permeability of compounds across Gram-negative bacterial membranes depends on many factors including physicochemical properties of the inhibitors. Herein, we show the optimization of pyridylureas leading to compounds with potent activity against Gram-negative bacterial species such as P.aeruginosa, E.coli and A.baumannii.

Porcupine is an O-acyltransferase that regulates Wnt secretion. Inhibiting porcupine may block the Wnt pathway which is often dysregulated in various cancers. Consequently porcupine inhibitors are thought to be promising oncology therapeutics. A high throughput screen against porcupine revealed several potent hits that were confirmed to be Wnt pathway inhibitors in secondary assays. We developed a pharmacophore model and used the putative bioactive conformation of a xanthine inhibitor for scaffold hopping. The resulting maleimide scaffold was optimized to subnanomolar potency while retaining good physical druglike properties. A preclinical development candidate was selected for which extensive in vitro and in vivo profiling is reported.

Protein kinase C iota (PKC-ι) is an atypical kinase implicated in the promotion of different cancer types. A biochemical screen of a fragment library has identified several hits from which an azaindole-based scaffold was chosen for optimization. Driven by a structure–activity relationship and supported by molecular modeling, a weakly bound fragment was systematically grown into a potent and selective inhibitor against PKC-ι.

Enhanced sensitivity to Wnts is an emerging hallmark of a subset of cancers, defined in part by mutations regulating the abundance of their receptors. Whether these mutations identify a clinical opportunity is an important question. Inhibition of Wnt secretion by blocking an essential post-translational modification, palmitoleation, provides a useful therapeutic intervention. We developed a novel potent, orally available PORCN inhibitor, ETC-1922159 (henceforth called ETC-159) that blocks the secretion and activity of all Wnts. ETC-159 is remarkably effective in treating RSPO-translocation bearing colorectal cancer (CRC) patient-derived xenografts. This is the first example of effective targeted therapy for this subset of CRC. Consistent with a central role of Wnt signaling in regulation of gene expression, inhibition of PORCN in RSPO3-translocated cancers causes a marked remodeling of the transcriptome, with loss of cell cycle, stem cell and proliferation genes, and an increase in differentiation markers. Inhibition of Wnt signaling by PORCN inhibition holds promise as differentiation therapy in genetically defined human cancers.

Over the past decade, academic groups and pharmaceutical companies have uncovered several components and targets for intervention in the Wnt pathway. One approach is to block Wnt signalling through the use of orally bioavailable small molecules that prevent Wnt ligand secretion. In recent years, the membrane bound O-acyl transferase (MBOAT) porcupine (PORCN) has emerged as a molecular target of interest in the search for clinical options to treat Wnt-driven cancers. This review shall provide an overview of the reported small molecule inhibitors for PORCN and discuss the progress made in identifying human disease models that are responsive to PORCN inhibitors.

The molecular structures of all but the R = Et/Y = NO2 derivative of the series of structures [(Ph2P(CH2)4PPh2){AuSC(OR)NC6H4Y-4}2] for R = Me, Et or iPr and Y = H, NO2 or Me, display anti-conformations with the carbonimidothioate ligands external to the dppb (Ph2P(CH2)4PPh2) bridge. In the exceptional structure, the thiolate ligands occupy positions proximate to the dppb bridge, an observation rationalized in terms of the dictates of crystal packing. Aurophilic (Au⋯Au) interactions are not observed in their molecular or in their crystal structures. In the Y = NO2 structures, C–H⋯O interactions dominate the crystal packing leading to chain (R = Me or iPr) and layer (R = Et) motifs. Synthons of the type {Au⋯S}2 dominate the crystal packing, leading to a chain, in one example, i.e. R = Me and Y = H. Similar {Au⋯S}2 synthons potentially appear in all the remaining structures except for R = Et and Y = H, but the Au⋯S distances are too long to be considered significant so that C–H⋯S interactions clearly dominate the crystal packing. With the exception of the layer motif found for the R = Et and Y = NO2 derivative, chain motifs, mediated by {Au⋯S}2, C–H⋯O or C–H⋯S interactions persist in the crystal structures.

Over the past decade, academic groups and pharmaceutical companies have uncovered several components and targets for intervention in the Wnt pathway. One approach is to block Wnt signalling through the use of orally bioavailable small molecules that prevent Wnt ligand secretion. In recent years, the membrane bound O-acyl transferase (MBOAT) porcupine (PORCN) has emerged as a molecular target of interest in the search for clinical options to treat Wnt-driven cancers. This review shall provide an overview of the reported small molecule inhibitors for PORCN and discuss the progress made in identifying human disease models that are responsive to PORCN inhibitors.

Wnt proteins regulate various cellular functions and serve distinct roles in normal development throughout life. Wnt signaling is dysregulated in various diseases including cancers. Porcupine (PORCN) is a membrane-bound O-acyltransferase that palmitoleates the Wnts and hence is essential for their secretion and function. The inhibition of PORCN could serve as a therapeutic approach for the treatment of a number of Wnt-dependent cancers. Herein, we describe the identification of a Wnt secretion inhibitor from cellular high throughput screening. Classical SAR based cellular optimization provided us with a PORCN inhibitor with nanomolar activity and excellent bioavailability that demonstrated efficacy in a Wnt-driven murine tumor model. Finally, we also discovered that enantiomeric PORCN inhibitors show very different activity in our reporter assay, suggesting that such compounds may be useful for mode of action studies on the PORCN O-acyltransferase.

Porcupine is a component of the Wnt pathway which regulates cell proliferation, migration, stem cell self-renewal, and differentiation. The Wnt pathway has been shown to be dysregulated in a variety of cancers. Porcupine is a membrane bound O-acyltransferase that palmitoylates Wnt. Inhibiting porcupine blocks the secretion of Wnt and effectively inhibits the Wnt pathway. Using high throughput screening, we have identified a number of novel porcupine inhibitors with diverse scaffolds. The pharmacophore requirements for our porcupine inhibitors were elucidated, and a pharmacophore model is proposed. Our compounds as well as all currently published porcupine inhibitors may be fitted to this model in low energy conformations with good superimposition of the pharmacophore elements. The model also explains the stereochemical requirements of our chiral porcupine inhibitors. The pharmacophore model was successfully used for designing 3 new series of porcupine inhibitors having a tricyclic xantine, a phtalimide, or a piperidine-maleimide scaffold.

X-ray crystallography shows the gold atoms in [R3PAu{SC(OMe)=NC6H4NO2-4}] (R = Et, Cy, Ph; 1-3, respectively) and [(Ph2P-R-PPh2){AuSC(OMe)=NC6H4NO2-4}(2)] (R = CH2, (CH2)2, (CH2)3, (CH2)4, Fc; 4-8, respectively) are linearly coordinated by phosphorus and thiolate-sulfur; weak intramolecular Au...O interactions are featured in all structures. The smaller ethyl substituents in 1 allow for supramolecular association via Au...S and Au...Au interactions that are not found in 2 and 3, which contain larger phosphorus-bound Cy and Ph groups, respectively. Intramolecular Au...Au interactions are found in the dppm, dppe, dppp, and Fc structures but not in the dppp analogue, for which an anti conformation was found. The structures have been correlated with the results from photophysical study conducted in the solid state. Thus, photoexcitation of 1-7 with lambda > 350 in the solid state and in solution produces green and blue luminescence, respectively. The spectra in each medium are remarkably similar to each other, and so the emission energy and excitation maxima observed for 1-7 appear to be independent of the nature of the ancillary phosphines, as well as the presence or absence of Au...Au interactions, either intermolecularly or intramolecularly.

The molecular structures of Ph3PAu · (S2CC5H6NH2-2) and (4-MeOC6H4)3PAu(S2CC5H6NH2-2) · CH2Cl2 display the expected linear S-Au-P coordination geometries. The hydrogen-bonding functionality in the 1,1-dithiolate ligands, i.e., —NH2 groups, allows for the formation of hydrogen-bonded, i.e., N—H…S, mediated chains in the respective crystal structures.

Porcupine (PORCN), a muti-pass integral membrane-bound-O-Acyl acyltransferase (MBOAT), resides in the in the endoplasmic reticulum (ER) and is required for biogenesis of Wnt ligands. The secreted mature Wnt ligands bind to their cognate receptors (Frizzled, LRP5/6 and transmembrane receptor ROR) to form the ligand - receptor complex which is capable to activate the Wnt-β-catenin signalling cascade and downstream signalling pathways such as mTOR, GSK3, Akt, and PKC. The deregulation of and aberrant activation of the various components of Wnt-β-catenin signalling pathway have been implicated in tumorigenesis, cell proliferation, survival and differentiation. Hyperactivity of PORCN is found to be associated with cancerous cell growth. Knockdown of Porcn mRNA significantly reduced the proliferation of breast cancer cells and resulted in the delay of MDA-MB-231 tumor formation in mouse xenograft models (Covey et al 2012). Loss of function mutations of RNF43, a negative regulation of Wnt-signalling via Frizzled receptor, is recently reported to be involved with pancreatic ductal adenocarcinoma. Inhibition of the PDAC cell lines bearing RNF43 mutations enhanced Wnt-β-catenin signalling and resulted in suppression of proliferation and differentiation of PDAC tumor cells (Jiang et al 2013). Taken together porcupine could be an attractive therapeutic approach for a particular Wnt-driven cancer population. We have identified the porcupine lead compounds (ETC-159, ETC-535, ETC-611 and ETC-539) from different novel chemical scaffolds. The aim of this study was to evaluate their pharmacokinetic properties and antitumor efficacy in different cancer mouse models, the murine MMTV-Wnt1 breast cancer and the human pancreatic HPAF-II cancer. All porcupine lead compounds had good oral pharmacokinetic properties with the absolute oral bioavailability greater than 42%. They had the maximum tolerated dose (MTD-7d) up to 200 mg/kg. They produced antitumor efficacy ranging from 24% to 79% at 1 mg/kg, 38% to 89% at 3 mg/kg, and 58 to 97% at 10 mg/kg in MMTV-Wnt1 tumor mouse model. In vivo inhibition of PORCN led to reduce the expression level of Axin2 in MMTV-Wnt tumors upto 8h. At 100 mg/kg, they produced antitumor efficacy ranging from 34% to 91% in human HPAF-II pancreatic xenograft mouse model. Of 4 porcupine lead compounds, ETC-159 demonstrated great oral pharmacokinetic properties and produced significantly antitumor efficacy (p value < 0.0001) in both cancer mouse models. ETC-1922159 was selected as the preclinical development candidate and currently is under investigation in Phase 1 clinical trial. Citation Format: Vishal Pendharkar, Yun Shan Chew, Vithya Manoharan, Choon Bing Low, Hongqian Esther Ong, Soo Yei Ho, Wei Ling Wang, Jeyaraj Duraiswamy Athisayamani, Babita Madan, David Virshup, Thomas Hugo Keller, May Ann Lee, Alex Matter, Jeffrey Hill, Kanda Sangthongpitag. In vivo pharmacokinetic properties and antitumor efficacy of porcupine lead inhibitors in the orthotopic murine MMTV-Wnt1 breast tumor model and the human HPAF-II pancreatic xenograft mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1172. doi:10.1158/1538-7445.AM2017-1172

A near-linear P—Au—S geometry is found for the Au atom in the title complex, (C6H11)3PAu[SC(OCH2CH3)=NC6H4{C(=O}OCH3-4)] or [Au(C11H12NO3S)(C18H33P)].

A linear coordination geometry defined by S and P atoms is found for Au in both components of the title 1:1 cocrystal, [Au(C6H15P)(C11H12NO3S)]·[Au(C6H15P)(C12H14NO3S)]. Pairs of molecules disordered over an inversion centre associate via Au⋯·S inter­actions and these dimeric units are connected into chains via C—H⋯O inter­actions.

The Au atom in the title complex, [(c-C6H11)3PAu(6-MP)]CH3CH2OH (6-MP is 6-mercaptopurinate) or [Au(C5H3N4S)(C18H33P)]·C2H6O, is linearly coordinated within an SP donor set. The solvent ethanol mol­ecules are associated with the complex via O—H⋯N inter­actions so that two ethanol mol­ecules bridge two 6-MP residues via a 12-membered {HO⋯HNCN}2 system.

Tankyrases constitute potential drug targets for cancer and myelin-degrading diseases. We have applied a structure- and biophysics-driven fragment-based ligand design strategy to discover a novel family of potent inhibitors for human tankyrases. Biophysical screening based on a thermal shift assay identified highly efficient fragments binding in the nicotinamide-binding site, a local hot spot for fragment binding. Evolution of the fragment hit 4-methyl-1,2-dihydroquinolin-2-one (2) along its 7-vector yields dramatic affinity improvements in the first cycle of expansion. A crystal structure of 7-(2-fluorophenyl)-4-methylquinolin-2(1H)-one (11) reveals that the nonplanar compound extends with its fluorine atom into a pocket, which coincides with a region of the active site where structural differences are seen between tankyrases and other poly(ADP-ribose) polymerase (PARP) family members. A further cycle of optimization yielded compounds with affinities and IC50 values in the low nanomolar range and with good solubility, PARP selectivity, and ligand efficiency.

Various mutations in the Wnt pathway contribute to aberrant activation of Wnt signaling, which is implicated in multiple cancers. Besides the mutation of Adenomatous polyposis coli (APC) or beta-catenin which causes the continuous activation of Wnt signaling by stabilizing beta-catenin, there are mutations of other genes such as RNF43 that regulate Wnt signaling at the level of the ligand or cell surface receptor. Inhibition of the secretion of all human Wnts by blocking their palmitoleoylation by the O-acyltransferase, Porcupine (PORCN), could be an alternative therapeutic approach. Here we have developed a compound with a novel pharmacophore that can inhibit PORCN activity and hence Wnt signaling in nanomolar concentration. In vivo efficacy study demonstrated that the compound is highly efficacious in preventing tumor growth in genetic modification model MMTV-WNT1 mouse. We have identified a subset of pancreatic cancer, cholangiocarcinoma and mucinous ovarian cancer cell lines that are sensitive to the compound. Most of these cell lines harbor mutations in RNF43. Xenograft tumor models derived from the cancer cell lines were found to be sensitive to the compound. Our results demonstrate that inhibiting the Wnt/beta-catenin pathway by targeting PORCN with small-molecule inhibitors in a subset of cancers with mutation in RNF43 is a feasible and nontoxic strategy to overcome the problem of redundancy of Wnts, thereby, providing new option for therapy in diseases with up regulated Wnt expression. Citation Format: Zhiyuan Ke, Babita Madan, Shermaine Q.y. Lim, Sifang Wang, Jenefer Alam, Soo Yei Ho, Duraiswamy Athisayamani Jeyaraj, Kakaly Ghosh, Yun Shan Chew, Li Jun Ding, Vithya Monoharan, Vishal Pendharkar, Esther Ong, Jeffrey Hill, Kanda Sangthongpitag, Thomas Keller, May Ann Lee, David M. Virshup. A novel Porcupine inhibitor is effective in the treatment of cancers with RNF43 mutations. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4449. doi:10.1158/1538-7445.AM2015-4449

Each gold atom in the binuclear title compound, [Au(2)(C(9)H(9)N(2)O(3)S)(2)(C(25)H(22)P(2))], is coordinated within an S,P-donor set that defines a slightly distorted linear geometry [S-Au-P angles = 172.77 (6) and 173.84 (6)°], with the distortion due in part to a close intra-molecular Au⋯O contact [2.968 (11) and 2.963 (4) Å]. The mol-ecule adopts a U-shaped conformation allowing for the formation of an aurophilic Au⋯Au inter-action [3.2320 (5) Å]. Mol-ecules are consolidated in the crystal structure by C-H⋯π inter-actions. Disorder was noted for one of the eth-oxy groups with two orientations being resolved in a 0.679 (16):0.321 (16) ratio.

In the title compound, [Au(C(9)H(9)N(2)O(3)S)(C(6)H(15)P)], two virtually identical mol-ecules comprise the asymmetric unit. These are connected by Au⋯Au [3.6796 (4) Å] and Au⋯S [3.6325 (18) and 3.5471 (18) Å] contacts, forming a dimeric aggregate. The presence of intra-molecular Au⋯O contacts [2.993 (5) and 2.957 (5) Å] is responsible for the slight deviations from the ideal linear coordination environments about the Au(I) ions. The conformation about the central C=N double bond is Z. Supra-molecular chains sustained by π-π [3.573 (4) Å] and C-H⋯π inter-actions are evident in the crystal structure. These are connected into layers via weak inter-molecular C-H⋯O inter-actions involving the nitro-group O atoms.

The dinuclear title complex, (Ph2PCH2CH2PPh2)[AuSC(OCH2CH3)=N(C6H5)]2 or [Au2(C9H10NOS)2(C26H24P2)], is centrosymmetric and a linear coordination geometry defined by S and P atoms is found for the Au atom. Supra­molecular chains mediated by C—H⋯S inter­actions and weakly associated {Au⋯S}2 synthons are evident in the crystal structure.

Two independent mol­ecules comprise the asymmetric unit of the title compound, C9H11NOS, each of which adopts an E conformation about the central C—N bond and exists in the thione form. N—H⋯S hydrogen-bond inter­actions link the independent mol­ecules into dimers.

Dysregulation of the Wnt signaling cascades is implicated in multiple disorders. There are 19 human Wnts that mediate signaling through diverse downstream pathways. To achieve maximum benefit from inhibition of Wnt signaling, targeting all of these pathways may be useful. The secretion and biological activity of all human Wnts requires palmitoylation mediated by Porcupine (PORCN), an endoplasmic reticulum-localized membrane bound O-acyltransferase. Several small molecule inhibitors of PORCN have been developed. Here we report a novel pharmacophore with derivatives that are nanomolar inhibitors of Wnt signaling. By a number of criteria, these compounds potently inhibit PORCN catalytic activity and hence suppress downstream Wnt-activated signaling pathways. The compounds effectively reduce autocrine Wnt signaling activity in selected cancer cell lines. The inhibitory activity is stereospecific, as an (R) enantiomer is inactive. Compounds with good oral bioavailability were tested for their in vivo activity and found to be highly efficacious in reversing tumor growth in both MMTV-WNT1 mice and of tumor xenografts. Treated tumors showed marked nuclear exclusion and decreased cytoplasmic staining of beta-catenin compared to vehicle controls. Importantly the treatment modulated downstream markers of Wnt signaling. No signs of toxicity were observed in mice at therapeutically effective doses. These results and our published results on C59 demonstrate that inhibiting the Wnt/beta-catenin pathway by targeting PORCN with small-molecule inhibitors is a feasible and nontoxic strategy. Use of porcupine inhibitors overcomes the problem of redundancy of Wnts, thereby, providing new options for therapy in diseases with high Wnt activity. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C248. Citation Format: Babita Madan, Zhiyuan Ke, Shermaine Q.y. Lim, Jenefer Alam, Soo Yei Ho, Duraiswamy A. Jeyaraj, Kakaly Ghosh, Yun Shan Chew, Jamal Aliyev, Li Jun Ding, Vishal Pendharkar, Sifang Wang, Kanda Sangthongpitag, Thomas Keller, May Ann Lee, David M. Virshup. Novel PORCN inhibitors are safe and effective in the treatment of WNT-dependent cancers. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C248.

The central CNC(=S)O entity in MeOC(=S)N(H)Ph, C8H9NOS, is effectively planar and shows that the mol­ecule exists as a thione. In the crystal structure, mol­ecules related by a centre of symmetry are associated via N—H⋯S interactions, forming thio­amide dimers.

The Au atom in the title compound, (p-MeOC6H4)3PAu(S2COEt) or [Au(C3H5OS2)(C21H21O3P)], exists in a linear geometry, such that the Au—S bond length is 2.3004 (8) A and Au—P is 2.2505 (7) A, and the angle at gold is 175.87 (3)°.

Sulfur- and phospho­rus-donor atoms define an approximately linear geometry about the Au atom in the title compound, [Au(S2CNEt2){(p-MeO-C6H4)3P}]. The key geometric parameters are Au—S 2.3350 (8) A, Au—P 2.2528 (7) A and an S—Au—P angle of 169.80 (3)°. The deviation from linearity is ascribed to a close intramolecular Au⋯S contact of 3.0564 (8) A.

The Au atom in the title compound, (c-C6H11)3PAu(S2CNEt2) or [Au(C18H33P)(C5H10NS2)], exists in a linear geometry so that Au—S is 2.3340 (11), Au—P is 2.2599 (10) A and the angle at gold is 171.61 (4)°. The distortion from linearity may be traced to the close approach of the non-coordinating S atom which is separated from the Au atom by 3.0859 (13) A.

The Au atom in the title compound, (p-MeOC6H4)3PAuCl or [AuCl(C7H7O3P)], exhibits a linear geometry so that the Au—Cl bond length is 2.2885 (9) A, Au—P is 2.2333 (8) A and the angle at gold is 175.94 (3)°.

The structures of R3PAu[SC(OMe)=NR′], for R = Ph, o-tol, m-tol or p-tol, and R′ = Ph, o-tol, m-tol, p-tol or C6H4NO2-4, feature linear P-Au-S coordination geometries with intramolecular Au⋯O or Au⋯π interactions depending on the substitution patterns of the R and/or R′ groups. For R = Ph, intramolecular Au⋯O interactions are observed exclusively but when R = p-tol, intramolecular Au⋯π interactions are found unless precluded by steric crowding, i.e. in the case when R′ = m-tol, or by electronic reasons such as the presence of an electron withdrawing nitro group, i.e. when R′ = C6H4NO2-4. In the latter case, aurophilic interactions (Au⋯Au = 3.0872(4) A) are formed, uniquely amongst the series. The mode of coordination of the thiolate ligands in these complexes, arising from either steric or electronic factors or both, has a profound influence on the supramolecular aggregation patterns operating in their crystal structures. In the solvent-free systems that feature intramolecular Au⋯O interactions, columns of molecules stack so that the thiolate residues interdigitate to a greater or lesser extent leaving the aryl groups of the phosphine ligands facing each other, forming phenyl embraces in the Ph3P species or being connected by C–H⋯π contacts involving methyl-H atoms in the isomeric tolyl3P structures. In structures featuring intramolecular Au⋯π interactions, the methoxy-O atom is more accessible for the formation of C–H⋯O contacts. Finally, in the cases where the nitro substituent is present, at least one of the nitro-O atoms is involved in C–H⋯O intercations. In summary, subtle changes in electronic character and/or steric profile of the phosphine and thiolate ligands are seen to influence, systematically, the crystal packing.

Structural investigations, i.e. solid-state (X-ray), solution (1H NMR) and gas-phase (theoretical), on molecules with the general formula MeOC(S)N(H)C6H4-4-Y: Y = H (1), NO2 (2), C(O)Me (3), Cl (4) have shown a general preference for the adoption of an E-conformation about the central C–N bond. Such a conformation allows for the formation of a dimeric hydrogen-bonded {⋯H–N–CS}2 synthon as the building block. In the cases of 1–3, additional C–H⋯O interactions give rise to the formation of tapes of varying topology. A theoretical analysis shows that the preference for the E-conformation is about the same as the crystal packing stabilisation energy and consistent with this, the compound with Y = C(O)OMe, (5), adopts a Z-conformation in the solid-state that facilitates the formation of N–H⋯O, C–H⋯O and C–H⋯S interactions, leading to a layer structure. Global crystal packing considerations are shown to be imperative in dictating the conformational form of molecules 1–5.