Carole J. R. Bataille

Synthesis of (−)-Hygromycin A: Application of Mitsunobu Glycosylation and Tethered Aminohydroxylation†

The natural product ( )-hygromycin A, ( )-1, was isolated from the fermentation of Streptomyces hygroscopicus in 1953 and shown to be a broad-spectrum antibiotic which also exhibits immunosuppressant activity. The mode of antibacterial action of the natural product has been shown to involve inhibition of the ribosomal peptidyl transferase activity, and hygromycin A binds to the ribosome in a manner that is closely related, but not identical, to that of chloroamphenicol. Recent interest from the pharmaceutical industry has centered around the possibility of using this compound, or analogues thereof, in the control of swine dysentery and other infectious diseases of economic importance in animal health.

Exploring the surfaceome of Ewing sarcoma identifies a new and unique therapeutic target.

Significance By investigating cell surface proteins of Ewing sarcoma we have identified an antigen that is uniquely expressed on these tumor cells compared with mesenchymal stem cells. This protein acts as a target for antibody drug conjugates that are internalized and can kill these tumor cells, presaging translating to clinical use in treating Ewing sarcoma, especially metastatic disease. The cell surface proteome of tumors mediates the interface between the transformed cells and the general microenvironment, including interactions with stromal cells in the tumor niche and immune cells such as T cells. In addition, the cell surface proteome of individual cancers defines biomarkers for that tumor type and potential proteins that can be the target of antibody-mediated therapy. We have used next-generation deep RNA sequencing (RNA-seq) coupled to an in-house database of genes encoding cell surface proteins (herein referred to as the surfaceome) as a tool to define a cell surface proteome of Ewing sarcoma compared with progenitor mesenchymal stem cells. This subtractive RNA-seq analysis revealed a specific surfaceome of Ewing and showed unexpectedly that the leucine-rich repeat and Ig domain protein 1 (LINGO1) is expressed in over 90% of Ewing sarcoma tumors, but not expressed in any other somatic tissue apart from the brain. We found that the LINGO1 protein acts as a gateway protein internalizing into the tumor cells when engaged by antibody and can carry antibody conjugated with drugs to kill Ewing sarcoma cells. Therefore, LINGO1 is a new, unique, and specific biomarker and drug target for the treatment of Ewing sarcoma.

Ligand-based virtual screening identifies a family of selective cannabinoid receptor 2 agonists

Graphical abstract

Thiazolidine derivatives as potent and selective inhibitors of the PIM kinase family

The PIM family of serine/threonine kinases have become an attractive target for anti-cancer drug development, particularly for certain hematological malignancies. Here, we describe the discovery of a series of inhibitors of the PIM kinase family using a high throughput screening strategy. Through a combination of molecular modeling and optimization studies, the intrinsic potencies and molecular properties of this series of compounds was significantly improved. An excellent pan-PIM isoform inhibition profile was observed across the series, while optimized examples show good selectivity over other kinases. Two PIM-expressing leukemic cancer cell lines, MV4-11 and K562, were employed to evaluate the in vitro anti-proliferative effects of selected inhibitors. Encouraging activities were observed for many examples, with the best example (44) giving an IC50 of 0.75μM against the K562 cell line. These data provide a promising starting point for further development of this series as a new cancer therapy through PIM kinase inhibition.

Dihydrobenz[e][1,4]oxazepin-2(3H)-ones, a new anthelmintic chemotype immobilising whipworm and reducing infectivity in vivo

Trichuris trichiura is a human parasitic whipworm infecting around 500 million people globally, damaging the physical growth and educational performance of those infected. Current drug treatment options are limited and lack efficacy against the worm, preventing an eradication programme. It is therefore important to develop new treatments for trichuriasis. Using Trichuris muris, an established model for T. trichiura, we screened a library of 480 novel drug-like small molecules for compounds causing paralysis of the ex vivo adult parasite. We identified a class of dihydrobenz[e][1,4]oxazepin-2(3H)-one compounds with anthelmintic activity against T. muris. Further screening of structurally related compounds and resynthesis of the most potent molecules led to the identification of 20 active dihydrobenzoxazepinones, a class of molecule not previously implicated in nematode control. The most active immobilise adult T. muris with EC50 values around 25–50μM, comparable to the existing anthelmintic levamisole. The best compounds from this chemotype show low cytotoxicity against murine gut epithelial cells, demonstrating selectivity for the parasite. Developing a novel oral pharmaceutical treatment for a neglected disease and deploying it via mass drug administration is challenging. Interestingly, the dihydrobenzoxazepinone OX02983 reduces the ability of embryonated T. muris eggs to establish infection in the mouse host in vivo. Complementing the potential development of dihydrobenzoxazepinones as an oral anthelmintic, this supports an alternative strategy of developing a therapeutic that acts in the environment, perhaps via a spray, to interrupt the parasite lifecycle. Together these results show that the dihydrobenzoxazepinones are a new class of anthelmintic, active against both egg and adult stages of Trichuris parasites. They demonstrate encouraging selectivity for the parasite, and importantly show considerable scope for further optimisation to improve potency and pharmacokinetic properties with the aim of developing a clinical agent.

Highlights of natural product synthesis

This report surveys the chemical literature for 2004 and 2005 and reports some of the highlights of natural products synthesis.

BRET-based RAS biosensors that show a novel small molecule is an inhibitor of RAS-effector protein-protein interactions.

The RAS family of proteins is amongst the most highly mutated in human cancers and has so far eluded drug therapy. Currently, much effort is being made to discover mutant RAS inhibitors and in vitro screening for RAS-binding drugs must be followed by cell-based assays. Here, we have developed a robust set of bioluminescence resonance energy transfer (BRET)-based RAS biosensors that enable monitoring of RAS-effector interaction inhibition in living cells. These include KRAS, HRAS and NRAS and a variety of different mutations that mirror those found in human cancers with the major RAS effectors such as CRAF, PI3K and RALGDS. We highlighted the utility of these RAS biosensors by showing a RAS-binding compound is a potent pan-RAS-effector interactions inhibitor in cells. The RAS biosensors represent a useful tool to investigate and characterize the potency of anti-RAS inhibitors in cells and more generally any RAS protein-protein interaction (PPI) in cells.

2,4-Diaminothieno[3,2-d]pyrimidines, a new class of anthelmintic with activity against adult and egg stages of whipworm

The human whipworm Trichuris trichiura is a parasite that infects around 500 million people globally, with consequences including damage to physical growth and educational performance. Current drugs such as mebendazole have a notable lack of efficacy against whipworm, compared to other soil-transmitted helminths. Mass drug administration programs are therefore unlikely to achieve eradication and new treatments for trichuriasis are desperately needed. All current drug control strategies focus on post-infection eradication, targeting the parasite in vivo. Here we propose developing novel anthelmintics which target the egg stage of the parasite in the soil as an adjunct environmental strategy. As evidence in support of such an approach we describe the actions of a new class of anthelmintic compounds, the 2,4-diaminothieno[3,2-d]pyrimidines (DATPs). This compound class has found broad utility in medicinal chemistry, but has not previously been described as having anthelmintic activity. Importantly, these compounds show efficacy against not only the adult parasite, but also both the embryonated and unembryonated egg stages and thereby may enable a break in the parasite lifecycle.

Chemical Instability and Promiscuity of Arylmethylidenepyrazolinone-Based MDMX Inhibitors

Targeting the protein–protein interaction between p53 and MDM2/MDMX (MDM4) represents an attractive anticancer strategy for the treatment of p53-competent tumors. Several selective and potent MDM2 inhibitors have been developed and entered the clinic; however, the repertoire of MDMX antagonists is still limited. The arylmethylidenepyrazolinone SJ-172550 has been reported as a selective MDMX antagonist; yet, uncertainties about its mechanism of action have raised doubts about its use as a chemical probe. Here, we show that, in addition to its unclear mode of action, SJ-172550 is unstable in aqueous buffers, giving rise to side products of unknown biological activity. Using an SJ-172550-derived affinity probe, we observed promiscuous binding to cellular proteins whereas cellular thermal shift assays did not reveal a stabilizing effect on MDMX. Overall, our results raise further questions about the interpretation of data using SJ-172550 and related compounds to investigate cellular phenotypes.

19. Using a Novel Combinatorial Non-Viral Vector and Small Molecules to Treat Familial Hypercholesterolaemia (FH)

Familial hypercholesterolaemia (FH) is a life-threatening genetic disorder characterised by elevated levels of plasma low density lipoprotein cholesterol (LDL-C). Loss-of-function mutations in the gene encoding the low density lipoprotein receptor (LDLR) are responsible for ~85% of all FH cases. We have previously generated mini-gene vectors carrying the human LDLR cDNA, driven by 10 kb of genomic DNA from the native human LDLR locus, encompassing a promoter region with all essential elements required for physiologically regulated expression (pLDLR-LDLR). We demonstrated that incorporation of the genomic DNA promoter elements resulted in long-term physiologically-regulated LDLR transgene expression that complemented Ldlr deficiency. Here we further enhance LDLR transgene expression by characterising and cloning in a miRNA, targeting Hmgcr (miR82) generating a combinatorial RNAi-LDLR vector (pLDLR-LDLR-miR82). We show in vivo that the combinatorial vector efficiently suppresses endogenous Hmgcr transcripts, which leads to an increase in LDLR transgene expression through induction of the LDLR promoter. In a preliminary study the pLDLR-LDLR-miR82 vector was able to significantly reduce total and LDL-C, in Ldlr−/− mice fed a 1% cholesterol diet at two and four weeks post vector delivery. We then carried out a longer term study in Ldlr−/− mice fed a 0.25% cholesterol diet, LDLR expression could be detected 12-weeks post-delivery with the plasmid able to be rescued as a functioning episome. LDL-C was significantly lowered throughout the study and this resulted in reduced atherosclerosis in the pLDLR-LDLR-miR82 vector treated mice. Here we demonstrate for the first time, that an episomal non-viral vector is able to significantly reduce LDL-C and the progression of atherosclerosis in a mouse model of FH. Based on the success of the miRNA to further enhance the lipid lowering of our non-viral vector, we went on to screen small molecules which can drive the expression of the human LDLR promoter. 216 molecules were screened, where we identified a novel series of small molecules that increased the LDLR in human and mouse cell lines at nano molar potencies. We then went on to elucidate the mechanism of action as squalene synthase inhibitors and demonstrated, that when used in combination with statins, these compounds give a much greater increase in LDLR expression than statins alone. These small molecules could be used in conjunction with low dose statins, alongside our non-viral vector to further enhance expression of the LDLR and provide greater therapeutic outcome for patients of FH.