CRUK Grand Challenge Initiative


Last month Cancer Research UK announced that it had awarded significant grants to several projects under its Grand Challenge Scheme. This scheme was set up by CRUK to fund ‘game changing research’ to try to address some of the leading problems in cancer research.

Seven grand challenge topics were set:

  • Challenge 1 – Develop vaccines to prevent non-viral cancers.
  • Challenge 2 – Eradicate EBV-induced cancers from the world.
  • Challenge 3 – Discover how unusual patterns of mutation are induced by different cancer-causing events.
  • Challenge 4 – Distinguish between lethal cancers that need treating, and non-lethal cancers that don’t.
  • Challenge 5 – Find a way of mapping tumours at the molecular and cellular level.
  • Challenge 6 – Develop innovative approaches to target the cancer super-controller MYC.
  • Challenge 7 – Deliver biologically active macromolecules to any and all cells in the body.

Sarah 1

https://iamstem.wordpress.com/2013/11/20/scientists-fingerprint-single-cancer-cells-to-map-cancers-family-tree/

The intention was to fund one project, but CRUK were so inspired by the applications that from a total of 56 bids, a total of 4 international teams have received funding of up to £20 million over five years.

  1. Professor Sir Mike Stratton, Principal Investigator – Identifying preventable causes of cancer
  2. Professor Greg Hannon, Principal investigator – Creating virtual reality maps of tumours
  3. Dr Jelle Wesseling, Principal Investigator – Preventing unnecessary breast cancer treatment
  4. Dr Josephine Bunch, Principal investigator – Studying tumour metabolism from every angle

Professor Mike Stratton’s team are working on identifying preventable causes of cancer by studying DNA mutational fingerprints from patients. Changes can occur in the DNA due to damage caused by environmental factors such as UV exposure or lifestyle behaviours like smoking and drinking alcohol. These leave a ‘scar’ in the DNA. The causes of some mutational fingerprints have already been identified (as shown in the figure) but there are many more where the causes are currently unknown.

Sarah 2

This ambitious project plans to study patient samples from over five continents to attempt to identify causes of more of these fingerprints in the hope that many common cancers may be prevented.

This research could also be extremely important in the longer term for oncology drug discovery. By gaining more information about the causes of DNA damage and how it is repaired, as well as identifying the early mutations that drive tumour growth, new targets for cancer treatments could be identified.

 

Blog written by Sarah Walker

References:

http://www.cancerresearchuk.org/funding-for-researchers/how-we-deliver-research/grand-challenge-award/funded-teams-stratton

http://www.sanger.ac.uk/news/view/sanger-scientists-win-20-million-grand-challenge-funding-cancer-research-uk

 

Live Cell Imaging – a cell Biologist’s Dream?


Biological science is renowned for is intrinsic variability that as Biologists we try to account for with controls galore. The cell biologist has the task of getting to know a huge variety of cell lines and primary cultures with their own preferences for nutrients, density and transfection conditions and individual tolerances to stress.

Andrea 1

We’re often left guessing at what the cells are up to between splitting or after treatment; what the best time-point is for end-point measurements; when a protein begins to be expressed.

What if we could watch our cells Big Brother style 24-7?

I am about to find out.

We are trialling the IncuCyte® ZOOM from Essen bioscience through April.

Andrea 3

This live-cell analysis system allows continuous monitoring of cells within the incubator. Monitoring can be label-free phase-contrast imaging to assess growth or coupled with fluorescent labels to assess cell death, protein expression or transfection efficiency.

The following paper gives an example of the advantages of live cell imaging for accurately and sensitively quantifying drug-induced cell death by multiplexing staining for lives cells with staining for cells undergoing cell death by apoptosis.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5261025/

Andrea 5

Andrea 6

They effectively measure drug-induced apoptosis controlling for differences in cell number between samples due to proliferation effects and dead cell detachment with a rapid, zero-handling method producing data consistent with gold standard methods in the field.

I’m looking forward to spying on my cells during the InCuCyte trial and hopefully rapidly generating some high quality data of my own.

Blog written by Andrea Gunnell

 

CLCA1 and TMEM16A: The link towards a potential cure for airway diseases


Numerous potentially harmful particles constantly enter our lungs. To guard against this, they are lined with a physical barrier called airway epithelium. In the conducting airways, this pseudostratified layer consists predominantly of mucus secreting goblet cells and ciliated cells. Their joint function is to trap and physically propel these particles out of the lung-a tightly regulated innate defence mechanism known as mucociliary clearance (MCC) 1.

Ciliated cells play a dual role in this process via ciliary beating and ion transport. The former is based on a coordinated wave-like motion of cilia. These are located on the apical membrane of the cell, layered by the periciliary liquid (PCL), which hydrates the airways and enables their smooth movement. Formation of PCL is a result of the water movement from serosa onto the apical surface through the tight junctions and is mediated by ion flow across the epithelium (Fig.1). A defect in this hydration mechanism results in conditions such as asthma, cystic fibrosis and chronic obstructive pulmonary disease1.

Karin 1

 

Figure 1. Ion transport hydration model in airway epithelium  (Hollenhorst, 2011)

Currently, one of the main therapeutic targets is the ion channel TMEM16A, a member of Calcium Activated Chloride Channel family (CaCC). In the lung, upregulation of its Cl and HCO3 secretion would promote PCL formation and re-establish airway homeostasis2. However, it has been demonstrated that a family of goblet-cell-derived proteins, known as Calcium-activated chloride channel regulators (CLCA), can regulate CaCC-mediated chloride currents. Chloride channel accessory 1 (CLCA1), one of the family members, and TMEM16A were found to be upregulated in response to inflammatory mediators, especially in conditions such as asthma and COPD, where they contribute to excessive mucus production3.

However, a recently published study by Sala-Rabanal et al. (2015) was the first to functionally link the two proteins, and specifically identify CLCA1 as a secreted modifier of TMEM16A. The hypothesis is that this effector protein acts in a paracrine fashion and exerts its effect via stabilising the TMEM16A channel dimer on the cell surface. As a result, it increases its surface expression and potentially elevates calcium dependent chloride currents, which could therefore increase MCC (Fig.2)4.

This makes both the CLCA1 and its site of interaction with TMEM16A, promising, and perhaps optimal, therapeutic targets for chronic obstructive airway diseases. Especially, since very few of the molecular players involved in mucus overproduction, driven by mucous cell metaplasia (MCM), have been identified so far5. Nevertheless, much more information will be required regarding the CLCA1-TMEM16A structure and interaction, within the MCC and MCM pathway.

Karin 2

Figure 2. Proposed mechanism of CLCA1-TMEM16A inter-/action (Sala-Rabanal, 2015)

Blog by Karin Smrekar

References

  1. Hollenhorst, M. I., Richter, K., Fronius, M. (2011). Ion Transport by Pulmonary Epithelia. Journal of Biomedicine and Biotechnology, 2011.
  2. Caputo, A., Caci, E., Ferrera, L., Pedemonte, N., Barsanti, C., Sondo, E., Pfeffer, U., Ravazzolo, R., Zeagara-Moran, O., Galietta, L.J.. (2008). TMEM16A, a membrane protein associated with calcium-dependent chloride channel activity. Science, 590-594.
  3. Alevy, Y.G., Patel, A.C., Romero, A.G., Patel,D.A., Tucker, J., Roswit, W.T., Miller, C.A., Heier, R.F., Byers, D.E., Brett, T.J., Holtzman, M.J. (2012), IL-13–induced airway mucus production is attenuated by MAPK13 inhibition. The Journal of Clinical Investigation, 122 (2); 4555-4568.
  4. Sala-Rabanal, M., Yurtsever, Z., Nichols, C.G., Brett, T.J. (2015). Secreted CLC1 modulates TMEM16A to activate Ca2+ -dependent chloride currents in human cells. eLife.
  5. Brett, T.J. (2015). CLCA1 and TMEM16A: the link towards a potential cure for airway diseases. Expert Review of Respiratory Medicine, 503-506.

 

The rise of diversity-oriented synthesis in drug discovery


Molecular diversity is a crucial feature in bioactive compound libraries. This makes sense as it would expand the chemical space around the studied biological targets or processes and therefore increase the chance to find hit compounds. During the 1990S and early 2000S, combinatorial chemistry was very popular within big pharmas as a privileged method to quickly generate diversity by simultaneously preparing multiple compound libraries; especially using the solid-phase synthesis techniques (i.e., functionalized lanterns and Merrifield resin beads).1 Yet, the major drawback is the lack of structural diversity (i.e., poor scaffold diversity) within the chemical series. Without throwing the baby out with the bathwater, combinatorial chemistry greatly contributes to fuel up many high-throughput screening campaigns and could be useful to assess quickly structure-activity relationships of different compounds having similar backbones. However, how can we efficiently achieve scaffold diversity? How can we navigate simultaneously into different regions of biologically relevant chemical space?

In my opinion, diversity-oriented synthesis (DOS) could be a potential answer to those questions.

The DOS approach considers the efficient and simultaneous synthesis of structurally different compounds with the purpose to probe large portions of the bioactive small molecules space.2 Compared to the target-oriented synthesis where each step is performed sequentially to yield a final product, DOS starts from simple and similar building blocks towards complex and diverse compounds, usually in few steps (Fig. 1). To be fruitful, four parameters have to be considered to create high molecular diversity: i) the building blocks, ii) the stereochemistry, iii) the functional groups and iv) the molecular skeleton, which is the most important criterion.

MB 1

Figure 1. Synthetic approach in combinatorial synthesis and DOS.

Obviously, DOS heavily depends on reliable, atom-economic and high-yielding reactions and must work on a wide range of susbtrates as well as functional groups. Reactions such as multicomponent reactions (Ugi, Passerini, Petasis), tandem/domino and pericyclic processes as well as ring-closing metathesis (RCM) amongst others are now widely used in DOS. Recently, Nielsen and Schreiber have noticed that several DOS methodologies followed three distinct phases: Build/Couple/Pair (B/C/P).3 The Build part correspond to the synthesis of the starting materials, the Couple part refer to coupling reactions to form linear precursors. Finally, the Pair phase refer to folding reactions that trigger intramolecular pairing between compatible functional groups.

As a good example, Marcaurelle et al. have reported an aldol-based B/C/P strategy for the generation of structurally diverse macrocyclic histone deacetylase (HDAC) inhibitors.4 Using different asymmetric syn– and anti-aldol reactions in the Build phase, four stereoisomers of a Boc-protected g-amino acid were generated. On the other hand, chiral amine partners consisted in both stereoisomers of O-PMB-protected alaninol. Thus, in the Couple phase, eight chiral amides were prepared by coupling the chiral acid and amine starting materials. The resulting amides were then reduced to generate the related secondary amines. The fun part starts in the Pair phase where three different reactions – a nucleophilic aromatic substitution (SNAr), a [3+2] azide-alkyne cycloaddition and a ring-closing metathesis (RCM) – were used to greatly diversify the whole matrix, thus providing a variety of macrocycles of different size (8- to 14-membered rings, Figure 2). Finally, the combinatorial diversification of the scaffolds resulting from the RCM reaction, further yielded a 14 400 macrolactams library. This has led to the discovery of a novel class of HDAC inhibitors.

MB 2

Figure 2. Aldol-based DOS strategy towards novel macrolactams inhibiting the HDAC enzyme by Marcaurelle et al.

Hence, by pushing the synthetic boundaries always further, DOS could serve as the perfect tool to rapidly interrogate the medicinally relevant chemical space.

Blog written by Mohamed Benchekroun

References

(1)          Carroll, J. Will Combinatorial Chemistry Keep Its Promise? Biotechnol. Healthc. 2005, 2 (3), 26–32.

(2)          Galloway, W. R. J. D.; Isidro-Llobet, A.; Spring, D. R. Diversity-Oriented Synthesis as a Tool for the Discovery of Novel Biologically Active Small Molecules. Nat. Chem. 2010, 1, 80.

(3)          Nielsen, T. E.; Schreiber, S. L. Towards the Optimal Screening Collection: A Synthesis Strategy. Angew. Chem. Int. Ed. 2008, 47 (1), 48–56.

(4)          Marcaurelle, L. A.; Comer, E.; Dandapani, S.; Duvall, J. R.; Gerard, B.; Kesavan, S.; Lee, M. D.; Liu, H.; Lowe, J. T.; Marie, J.-C.; Mulrooney, C. A.; Pandya, B. A.; Rowley, A.; Ryba, T. D.; Suh, B.-C.; Wei, J.; Young, D. W.; Akella, L. B.; Ross, N. T.; Zhang, Y.-L.; Fass, D. M.; Reis, S. A.; Zhao, W.-N.; Haggarty, S. J.; Palmer, M.; Foley, M. A. An Aldol-Based Build/Couple/Pair Strategy for the Synthesis of Medium- and Large-Sized Rings: Discovery of Macrocyclic Histone Deacetylase Inhibitors. J. Am. Chem. Soc. 2010, 132 (47), 16962–16976.

 

Some useful tools to give your pharmacokinetics ‘wings’


stephen-brand

Translational research is all about finding novel therapeutic targets and seeing if they’re relevant to a disease. One of the most challenging (and possibly nerve-wracking) scenarios for a drug-discovery team can be investigating a ‘promising’ new target – the scientific and commercial benefits can be profound. In some circumstances, standard biological target validation methods such as knock-out mice, antibodies, etc. which could give confidence in the concept might not be possible. In which case the future of the project may well rely on getting chemical validation in an animal.

To a medicinal chemist this sort of programme will look very different to your standard me-too-we-want-a-slice-of-the-pie-type drug discovery project where the expected outcome is an exquisitely drug-like and squeaky clean molecule ready for the clinic (ideally!). The emphasis will be more on quickly finding a ‘tool compound’ that ‘finds and binds’ your new target so you can see if it has the desired effect in an in-vivo disease model. Finding a compound which binds is usually the easier part, but because increasingly more challenging targets [i.e. with fussy active sites] are being explored the search for a tool with great binding AND great pharmacokinetics can be a nightmare [I’m thinking getting Bcl-2 inhibitors into the brain, for instance]. You now have a couple of options – use skill and tenacity (and time and money) to optimise your compound’s PK, or use a pharmacokinetic ‘get out of jail free card’ to help by-pass the most frequently encountered barriers….

  1. The Gut Wall: For a poorly absorbed compound (low solubility/permeability) the gut can be by-passed by simply injecting a compound (obvious!), which probably results in significantly better exposure. If i.v. injection doesn’t provide sustained drug levels however (perhaps due to high clearance), an osmotic pump1 can be implanted subcutaneously. Osmotic pumps consist of a capsule containing drug and osmogens, coated with a semipermeable membrane. As the core absorbs water, hydrostatic pressure pushes the drug solution out at a controllable rate through the delivery ports – hey presto, sustained delivery!

 

 

Figure 1. An osmotic pump allows controllable and sustained compound exposure: http://www.alzet.com/products/ALZET_Pumps/howdoesitwork.html

 2. The Liver: The hepatic reductase null mouse (HRN) is a transgenic mouse developed by Cancer Research UK, which has the Por gene knocked-out. Since this gene encodes the reductase that regenerates the entire cytochrome p450 system, these mice have no hepatic p450 activity. If first-pass metabolism is the cause of poor PK, then using HRN mice can markedly increase circulating drug levels. [NB: comparison of circulating drug levels in HRN versus wild-type mice can also indicate whether hepatic clearance is your issue and whether efficacy or toxicity is caused by formation of a metabolite]. A comparable chemical cytochrome knock-out can be achieved by pre-administration with the pan-Cyp inhibitor 1-aminobenzotriazole3.

stephen-brand3-jpg

Figure 2. Mean concentration time profiles of (A) docetaxel, (B) midazolam, and (C) theophylline in HRN and WT mice (from Boggs JW et. al. Mol Pharm. 2014 Mar 3;11(3):1062-8).

 3. The Blood-Brain Barrier: There are some really exotic methods under investigation to circumvent the blood-brain barrier [including hyperosmotic blood-brain barrier opening and ‘trojan horse’ methods using antibodies or surface-modified liposomes which hijack endothelial cell transcytotic mechanisms]4. However, the P-glycoprotein, an ATP-driven drug efflux transporter is most commonly responsible for restricting access of experimental compounds into the brain5. Again, transgenic and chemical tools are available which can by-pass this obstacle to improve delivery of intrinsically permeable compounds to CNS targets. For example, inhibition of P-glycoprotein by the inhibitor Valspodar increases taxol levels in the brain by ten-fold allowing efficacy against glioblastoma6. However, Elacridar is a more commonly used tool to inactivate P-gp at the intestinal or blood-brain barrier, since it has better PK.

stephen-brand4

Recently Cornell researchers showed that transiently reducing expression of P-gp with the approved drug Lexiscan can open the BBB for a brief window of time – long enough to deliver various therapies to the brain.7 Transgenic knock-out mice [i.e. mdr1a/1b (-/-)] are also available which do not express functional P-gp and these can be used to engage CNS targets with otherwise non CNS penetrant tool molecules.8

Any one of these tools may just give your compound wings and help you better investigate your novel target.

     Blog written by Stephen Brand        

 REFS:

  1. Osmotic Drug Delivery System as a Part of Modified Release Dosage Form. ISRN Pharm. 2012, 528079. doi: 10.5402/2012/528079.
  2. Inactivation of the hepatic cytochrome P450 system by conditional deletion of hepatic cytochrome P450 reductase. J Biol Chem 2003; 278: 13480–6. doi: 10.1074/jbc.M212087200
  3. In vitro and in vivo characterization of CYP inhibition by 1-aminobenzotriazole in rats. Biopharmaceutics & Drug Disposition. 2016, 37, 1099. doi: 10.1002/bdd.2000.
  4. A review of nanocarrier-based CNS delivery systems. Curr Drug Deliv. 2006;3:219–232.
  5. Blood-brain barrier drug targeting: the future of brain drug development. Mol Interv. 2003; 3: 90–105. doi: 10.1124/mi.3.2.90.
  6. Transport of paclitaxel (Taxol) across the blood-brain barrier in vitro and in vivo. J Clin Invest 2002;110:1309–1318. doi: 10.1172/JCI15451.
  7. http://www.nature.com/scibx/journal/v4/n39/full/scibx.2011.1080.html
  8. Normal viability and altered pharmacokinetics in mice lacking mdr1-type (drug-transporting) P-glycoproteins. Proc Natl Acad Sci U S A. 1997, 94(8), 4028-33.

 

 

The endocannabinoid system: an emerging target in neurological and neurodegenerative diseases


The endogenous cannabinoid system (ECS) has been described as a conserved lipid-signalling network modulating neuronal functions and inflammatory processes, potentially involved in the aetiology of certain human lifestyle diseases. Endogenous cannabinoids (ECBs), such as Anandamide (AEA) and 2-arachidonoylglycerol (2-AG), activate type-1 and type-2 cannabinoid receptors (CB1R and CB2R) to modulate a wide range of responses (pain, appetite, motility, sleep, thermoregulation, cognitive and emotional states) and the actions of these signalling lipids are rapidly terminated by cellular reuptake and subsequent hydrolysis operated by a number of enzymes. The fatty acid amide hydrolase (FAAH) was originally identified as the enzyme responsible for AEA hydrolysis and to be also the main regulator of the endogenous tone of AEA in vivo. In addition to FAAH, monoacylglycerol lipase (MGL) was later identified as additional ECBs-metabolizing enzyme, playing a pivotal role in the catabolism and homeostasis of the 2-AG in the central nervous system.(1)

samuele

Figure 1. – Schematic representation of the main elements of the ECS.

In the past few years, an increasing body of evidence has suggested the ECS as a valuable target in several neurological and neurodegenerative diseases, since a hypofunctionality or dysregulation of this system may be responsible for some of the symptomatology of Alzheimer Disease, Huntington Disease, Multiple Sclerosis (MS), and Amyotrophic lateral sclerosis.(2)

Giving that, small molecules able to modulate the ECS, by inhibiting ECBs degrading enzymes and increasing ECBs tissue levels, could represent an interesting tool to address the abovementioned pathologies. These compounds are also less likely to cause psychoactive effects related to direct agonism of CB1R while maintaining the beneficial effects of CB1R/CB2R activation.(3)

Some interesting results have been achieved with the synthesis of a novel class of potent and selective MGL inhibitors tested in mice suffering from experimental autoimmune encephalomyelitis (EAE), a rodent demyelinating disease model universally accepted as an animal model of MS.(4) As proposed, in vivo administration of MGL inhibitors reduces the clinical severity of the EAE, induces re-myelinisation of damaged neurons and diminishes neuroinflammation. These encouraging results support the hypothesis of a tight intersection between the ECS and MS, suggesting MGL inhibition as an innovative therapeutic approach for treating MS.

Other recent investigations have addressed the involvement of ECS and ECBs levels in autism.(5) Being this uniquely human, there are only a few validated animal models useful to clarify the effects of ECBs-metabolizing enzymes inhibitors. However, an inherited disorder called Fragile X syndrome (FXS), caused by mutations in the fmr1 protein, produces autistic features in a high percentage of patients affected by this pathology. Thus, fmr1 knockout mice provide a good animal model to identify novel targets for autism. It has been reported that the ablation of fmr1 gene also causes dysfunctions on 2-AG metabolism. Then, stimulation of 2-AG signalling could be a useful treatment for mitigating FXS symptoms, since it is able to restore synaptic activity through type I metabotropic glutamate activation. These evidences highlight once again how important is the role of ECS in neurological disorders, pointing out the usefulness of efficient ECS tone modulators.

Blog by Samuele Maramai

  1. Pharmacol Rev. 2006, 58 (3), 389–462
  2. British Journal of Pharmacology, 2010, 160, 480–498
  3. Recent Patents on CNS Drug Discovery, 2012, 7, 49-70
  4. J. Med. Chem. 2016, 59, 2612−2632
  5. Neurotherapeutics, 2015, 12, 837–847

Will PTP1B be a new therapeutic option for T2DM and Obesity?


Insulin and Lectin are two hormones which play crucial roles in energy storage and peripheral energy uptake. Resistance to these hormones is a hallmark for both Type 2 Diabetes Mellitus (T2DM) and obesity1. Nearly 220 million people are living with diabetes and WHO projected the death due to diabetes would double between 2005 and 20302. The global epidemic nature of T2DM and obesity demand the need for new therapeutic approaches. PTP1B stands out in the PTP family as a negative regulator of insulin signal transduction pathway through its ability to dephosphorylate and inactivate the insulin receptor3. PTP1B also negatively regulates the leptin signalling pathway by dephosphorylating JAK2 (a phosphorylated tyrosine kinase) in the hypothalamus. Leptin is a key hormone directly associated with obesity that regulates food intake and energy expenditure4,11.

sri-1

Fig.1: PTP1B dephosphorylates the insulin receptor during its biosynthesis in the endoplasmic reticulum (ER)4

Natural products like prenylated xanthones, flavonoids, bromophenols, phenolic acids, cumarins, terpenes, steroids were isolated and tested to have potent PTP1B inhibition of 1.6-30.0 µmol/L5. These natural products have opened the gate to many small molecule inhibitors for PTP1B. However, carboxylates and phosphonates with nanomolar inhibition have failed to progress to the clinic due to poor membrane penetration6.

Many studies have postulated that existing anti-diabetic drugs belonging to the thiazolidinediones (TZDs) family, commonly known as glitazones (rosiglitazone7, pioglitazones etc.), could inhibit PTP1B8. Early competitive PTP1B inhibitors based on Vanadium compounds (vanadates and pentavanadates) have significant therapeutic values in human but they are not specific8,11. Series of benzofurans, benzothiophenes and phosphonates have been synthesised and patented as potential PTP1B inhibitors6,8. Unfortunately, none of them has made Phase II clinical trials9. Ertiprotafab from Wyeth, the first PTP1B inhibitor, was halted in Phase II due to data inconsistencies10.

Selectivity6,11 and bioavailability12 are the main challenges in developing potent PTP inhibitors. The PTP1B catalytic site shares structural motifs of other enzymes of PTP family and is highly charged. Consequently, highly charged inhibitors with very strong PTP1B inhibition lack biovailability11. Achieving selectivity against TC-PTP13 is the most challenging task for medicinal chemists. Many clinical trials, patent applications and drugs validation experiments proves that PTP1B has emerged as a novel target for the management, treatment of T2DM. However, the journey in the search for selective PTP1B inhibitors has been facing many pitfalls.

Interestingly, current phase II trial on Trodusquemine14 and PTP1B antisense oligonucleotides (IONIS-GCGRRX) by Ionis pharmaceuticals15 could be an alternate therapeutic option for T2DM and obesity.  At least one of the clinical candidates in Phase II studies will receive green signal from FDA in few years’ time

Blog by Srinivasan Natarajan

References

  1. D.Popov, Biochemical and Biophysical Research Communications, 2011, 410, 377-381

www.sciencedirect.com/science/journal/0006291X/410/3

  1. WHO diabetes fact sheet available from

http://www.who.int/mediacentre/factsheets/fs312/en/

  1. S.Koren and I.G Fantus., Best Practice & research Clinical Endocrinology & Metabolism, 2007, 21(4), 621-640

https://www.ncbi.nlm.nih.gov/pubmed/18054739

  1. J.Montalibet and B.P.Kennedy., Drug Discovery Today: Therapeutic Stragies, 2005, 2, 129-135.

www.sciencedirect.com/science/article/pii/S1740677305000069

  1. C.S JIANG, L.LIANG and Y GUO, Acta Pharmacologica Sinica (2012) 33: 1217–1245

https://www.ncbi.nlm.nih.gov/pubmed/22941286

  1. H.Cho Vitamins and Harmones, V 91, chapter 17, 2013, Elsevier Inc.,

https://www.ncbi.nlm.nih.gov/pubmed/23374726

  1. The antidiabetic drug rosiglitazone was withdrawn from European market since 2010 due to the increased risk of heart attack

https://en.wikipedia.org/wiki/Rosiglitazone

  1. Review by A.K Tamarkar and A.K. Rai, Expert Opin. Ther. Patents, 2014, 24(10), 1-15.

https://www.ncbi.nlm.nih.gov/pubmed/25120222

  1. Review by M.L.Tremblay et al., Crit.Rev.Biochem.Mol.Biol., 2013, 48(5), 430-445

https://www.ncbi.nlm.nih.gov/pubmed/23879520

  1. DV. Erbe et al. Molecular Pharmacology, 67(1), 69-77.

http://molpharm.aspetjournals.org/content/67/1/69

  1. S.Koren, I.G. Fantus, Best Practice & Research Clinical Endocrinology & Metabolism, 214, 621-640.

http://www.sciencedirect.com/science/article/pii/S1521690X07000814

Tonks N.K et al., Nature Chemical Biology, 2014, 10, 558-568

http://www.nature.com/nchembio/journal/v10/n7/abs/nchembio.1528.html

  1. H.Oh et al., Molecules, 2015, 20, 11173-11183

www.mdpi.com/1420-3049/20/6/11173/pdf

  1. T.Tcell PTP (TC-PTP) which linked to the development of several inflammatory disorder including type 1diabetes, Crohn disease and rheumatoid arthritis (J.Am.Chem.Soc.,2009, 131(36), 13072-79)

http://pubs.acs.org/doi/pdf/10.1021/ja903733z

  1. K.A. Lantz et al. Obesity, 2010, 18(8), 1516-1523.

https://www.ncbi.nlm.nih.gov/pubmed/20075852

  1. Phase II for IONIS-GCGRRX completed in January 2017. See the company website http://www.ionispharma.com/pipeline/

also see https://www.ncbi.nlm.nih.gov/pubmed/25197025  for anti -sense oligos for PTP1B

 

 

 

 

Making ‘Marvelous Medicines’ at the Brighton Science Festival


As part of the Brighton science festival the Sussex Drug Discovery Centre (SDDC) has participated for the last two years by doing an activity at the bright sparks event. The bright sparks weekend is aimed at 7-14 year olds and is the festival’s flagship event where there are over 50 stalls, stands and shows across the two days.

The SDDC activity aimed to do a journey though drug discovery called Making Marvelous Medicines. We did this by creating 4 stations of activity lasting 50 minutes. The 4 stations included: What are proteins, Designing Drugs, Synthetic Chemistry and Testing Drugs.

What Are Proteins ?

This station aimed to introduce the concept of proteins, by explaining their role as tiny machines doing millions of jobs that allow us to function healthily.james-1

To illustrate the “power of proteins” the enzyme catalase was used in liver to degrade hydrogen peroxide in our bubbly volcano experiment. An animated video of the motor protein kinesin was also used, and the use of ATP as protein food to give them energy was also introduced.

 

Designing Drugs

Now we introduced a ATP “eating” protein from tuberculosis, using molymods the children built molecules to fit into the ATP binding pocket of this protein. We then introduced a human ATP binding protein and tested the selectivity of the molecule.

Synthetic Chemistry

Participants were introduced to the concept of a chemical reaction using baking as an analogy: different reagents (“ingredients”) can be combined in order to make new chemical products e.g. a new medicine. The young people carried out their own reaction to make their “drug”  – we used the popular “golden rain” precipitation reaction between potassium iodide and lead nitrate https://www.youtube.com/watch?v=zJkv0HiqApo.

Gasps of awe and wonder came from the young scientists (and the adults with them) when two seemingly colorless solutions formed a bright yellow solid when mixed together.  The student demonstrators also recrystallized the products the children had formed in order to explain the importance of purifying medicines that are made in a lab.

  Testing Drugs

In the final stall, we aimed to simulate a biochemical assay to test our drugs effectiveness. This assay tuned blue for negative and pink for positive. The actual reagents used for this were Phenolphthalein and Thymolphthalein.

james-6

Feedback from parents and children was really positive and the audience grasped the key concepts. Parents were often just as interested as the children. At the end some children left comments on the white board.

james-7

Blog written by James Noble [PhD Student]

 

 

 

 

 

Synthesise a CNS drug that can cross the blood brain barrier?


Central nervous system (CNS) drugs include analgesics, sedatives, and anticonvulsants, with drugs being used to treat the effects of a wide variety of medical conditions such as Alzheimer’s disease, Parkinson’s disease, and depression. More than 1 billion people globally suffer from a CNS disease, with one in five Americans taking at least one psychiatric drug. In the US and Europe combined, the overall cost of the economic burden of CNS diseases is estimated to be more than $2 trillion, with that figure expecting to triple by 2030 (1). Whilst most pharmaceutical companies are patient centric, these figures are financially appealing. However, development of therapies for CNS diseases has lagged behind that for other therapeutic areas. CNS drugs can take more than 20 months longer to develop than other drugs, with attrition rates greater than 50%. These failures can be attributed to a number of reasons such as inadequate dosage to hit the therapeutic target, high placebo effect, high patient dropout rate, inaccuracies of preclinical disease models, and incomplete understanding of brain disease mechanisms. (1)

One of the challenges of working on a CNS drug discovery project is for the drug to traverse the blood-brain barrier (BBB). The BBB protects the brain from most pathogens, sheltering it from the systemic circulation. It also prevents most large molecule neurotherapeutics and more than 98% of all small molecule drugs reaching the brain from the bloodstream, the tight junctions of the endothelial cells lining brain capillaries restricting paracellular movement of substances across the BBB. The BBB serves roles other than that of blocking circulating substances from entering the CNS. It also facilitates and regulates the entry of many substances that are critical to CNS function and secretes substances into the blood and CNS. These extra-barrier functions allow the BBB to influence the homeostatic, nutritive, and immune environments of the CNS and to regulate the exchange of informational molecules between the CNS and blood. (3)

High attrition rates of preclinical and clinical drug candidates led Wager et al (4) to design a tool based on key physicochemical properties (clogP, clogD, molecular weight, topological polar surface area, hydrogen bond donors, and pKa) that would enable multiparameter optimisation (MPO) of druglike properties to accelerate the identification of drug candidates with optimal pharmacokinetic and safety profiles. After nearly 8 years of using this tool at Pfizer, Wager et al have reported a reduction in the number of compounds submitted to exploratory toxicity studies and an increase in the survival of the CNS MPO candidates through regulatory toxicology into first in human studies. (5) The tool has also been used outside of Pfizer to reduce attrition and improve compound quality in the design phase.

An understanding of the barrier and extra-barrier aspects of BBB physiology is also critical to developing drugs that can access the CNS. A recent CNS paper by Patel et al (6) discusses several key approaches for brain targeting including physiological transport mechanisms such as adsorptive-mediated transcytosis, inhibition of active efflux pumps, receptor-mediated transport, cell-mediated endocytosis, and the use of peptide vectors. Drug-delivery approaches comprise delivery from microspheres, biodegradable wafers, and colloidal drug-carrier systems (e.g., liposomes, nanoparticles, nanogels, dendrimers, micelles, nanoemulsions, polymersomes, exosomes, and quantum dots). These alternative approaches look promising.

The Canadian company Angiochem is using a physiological approach to gain entry across the BBB. They have engineered ANG1005, an Angiopep-2 paclitaxel conjugate to gain entry into the brain by targeting lipoprotein receptor-related protein (LRP-1), which is one of the most highly-expressed receptors on the surface of the BBB.  Once inside the brain, ANG1005 enters tumour cells using the same receptor-mediated pathway through LRP-1, which is upregulated in various cancer cells including malignant glioma and metastatic cancers in the brain. (7) Phase II data presented in October 2016 shows ANG1005 has demonstrated clinical benefit, both intracranially and extracranially in pre-treated breast cancer patients with recurrent brain metastases. (8)

Blog written by Kamlesh Bala

References

(1)www.parexel.com/files/4314/4113/4032/Venturing_Into_a_New_Era_of_CNS_Drug_Development_to_Improve_Success.pdf

(2) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC539316/

(3) https://bmcneurol.biomedcentral.com/articles/10.1186/1471-2377-9-S1-S3

(4) ACS Chem Neurosci. 2010 Jun 16;1(6):435-49

(5) ACS Chem. Neurosci. 2016, 7, 767−775

(6) Patel, M.M. & Patel, B.M. CNS Drugs (2017).

(7) http://angiochem.com

(8) http://angiochem.com/angiochems-ang1005-shows-clinical-benefits-and-prolonged-survival-breast-cancer-patients-brain

 

A powerful small molecule; believing in GABA


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GABA (γ-aminobutyrate) is the major inhibitory neurotransmitter in the mammalian brain. It contributes to the all-important excitatory-inhibitory balance of neuronal communication. Dysfunction of the GABAergic system is implicated in disease, such as epilepsy, insomnia, schizophrenia and anxiety disorders. The history of GABA, from when it was first discovered to when its power as an inhibitory neurotransmitter was accepted, is an interesting one. It is wrapped up in personal accounts of the scientists involved, and looking back at the winding path of acceptance is fascinating.[1],[2],[3]

The story starts with the discovery of a ninhydrin-reactive material in mouse brain tumours by Eugene Roberts and Sam Frankel in 1949.[4] GABA had been known since 1910, of course, and had been found in bacteria and fungi and potatoes.[5] Once the structure of this ninhydrin-reactive material was confirmed to be GABA by Sidney Udenfriend, Roberts scribbles “the brain is like a potato!” in his notebook, and sets about proving its biological significance. [6],[7]

Roberts and Frankel’s work was published in 1950 for a conference at which Jorge Awapara also reported the presence of an “unidentified amino acid” found only in the brain.[8] By the time of the conference Awapara had also recognised it was GABA. At the conference a room-shortage led these two into close proximity, and Awapara and Roberts apparently agreed that Roberts would continue working on metabolism of GABA, and Awapara would continue working on the metabolism of taurine.7b

Six years pass, and scientists were still questioning whether the presence of GABA in the brain meant it had a role in signal conductance.[9] It should be noted that the debate over whether synaptic transmission was electrical or chemical had only just reached its chemical conclusion.[10] Ernst Florey had found Factor I, a chemical of unknown composition, extracted from mammalian brain and which inhibited the crayfish muscle system amongst others.[11] With help from Merck scientist Alva Bazemore, they purified over 45 kg of cow brain, and, using over 450 L of acetone they managed to yield crystalline Factor I. It was GABA, obviously.[12] There were still things to clear up, however, as some of their earlier work on the spinal cord of cats was initially unrepeatable by David Curtis, a fact now anecdotally put down to the allosteric modulation by the barbiturates also used in the experiments, or contamination of glycine in Florey’s earlier samples.11, [13]

Evidence against GABA being a neurotransmitter was accruing. The fact that GABA was so widespread in the brain was a worry for many in the field. “It’s just a metabolic wastebasket” remarked one great neurochemist.7b Strychnine was known to inhibit transmission in the spinal cord, and yet did not compete with GABA, which was another point of confusion at the time. With hindsight we know it was the as-yet-undiscovered glycine receptors in the spine causing havoc here.

Some scientists remained convinced there was more to the story, and Eugene Roberts was one of them. “Stop bringing your GABA solutions to our labs,” pleaded biologists, daily. “They take up room, and we’re not going to test them.”

In 1959 a notable conference was convened to hear the latest research and clear up the confusion. This proceeding (the 1st Interdisciplinary Conference on GABA) at a nearby pub (City of Hope Research Institute) was attended by many of the leading people in the field. Excitement was in the air as scientists from Australia, Canada, England, France, Hungary, Japan, the United States and the former Soviet Union bustled together, spilling pints and talking Neuroanatomy. Most researchers had a top night, and left feeling like they had made life-long friends and collaborations from all over the world.

GABA itself, however, fared badly. It was not going to join the echelons of the neurotransmitters quite yet. Alongside everything else it was seen not to have a rapid, enzymatic degradation pathway, unlike the newly-discovered acetylcholine neurotransmitter. This was thought to preclude it from involvement in rapid on-off communication. GABA was a metabolite with some generalised depressant nature, but that was all.[14]

It was not until nearly ten years later that unequivocal proof was published by Krešimir Krnjević and Susan Schwartz in 1967 that GABA was shown to be the major inhibitory neurotransmitter.[15] Intracellular recordings, as well as pharmacological tests revealing selective block by picrotoxin and bicuculline, clearly demonstrated GABAergic transmission.[16] After this proof, there was an exponential growth in GABA research. Writing in 1974, Eugene Roberts says ‘In the 25 years since the discovery of GABA … the status of the compound has passed from that of a biochemical curiosity and physiological enigma to that of a major inhibitory transmitter.’[17] At fifty years GABA receptors are shown to have decisive roles in many diseases, and they become big targets in drug discovery, including big-hitting benzodiazepines and general anaesthetics.[18] At 67 years, there are a huge 74,000 references containing ‘gamma-aminobutyric acid’ on Scifinder Scholar.[19]

The mixture of personal and peer-reviewed literature accounts of how GABA came to be accepted is what makes it fascinating. It is useless to deny that the direction of any scientific progress is open to contemporary influences and personal preferences. Perhaps it just reminds us that, as Carl Sagan writes: “Nature is always more subtle, more intricate, more elegant than what we are able to imagine.” And that means the path to understanding this transmitter will never stop winding.

Blog written by Rosemary Huckvale

POST SCRIPTS

  1. Dr Eugene (Gene) Roberts died last year on 8th November 2016 at the age of 96. His obituaries can be found here.
  2. This blog hopes to relate only a small portion of the history surrounding the establishment of GABA as a major inhibitory transmitter. There will have been other important contributions not mentioned here.

REFERENCES

[1] Johnston, G.A.R, GABA Australis, some reflections on the history of GABA receptor research in Australia, Pharmacological Research, article in press, 2016.

[2] Avoli, M., Krnjević, K., The Long and Winding Road to Gamma-amino-butyric acid as neurotransmitter The Canadian Journal of Neurological Science, 43:219-226, 2016.

[3] Krnjević, K. How does a little acronym become a big transmitter? Biochemical Pharmacology, 68:1549-1555, 2004.

[4] a) Roberts, E. and Frankel, S. γ-aminobutyric acid in brain. Federation Proceedings 9:219, 1950. b) Roberts, E. and Frankel, S. γ-aminobutyric acid in brain: its formation from glutamic acid. Journal of Biological Chemistry 187:55-63, 1950.

[5] Steward FC, Thompson JF, Dent CE. γ-Aminobutyric acid. A constituent of the potato tuber? Science 110:439-440, 1949.

[6] Udenfriend, S. Identification of gamma-aminobutyric acid in brain by the isotope derivative method. Journal of Biological Chemistry 187:65-9, 1950.

[7] Roberts, E.. Gamma-aminobutyric acid, Scholarpedia, 2(10):3356, 2007. B) Roberts, E., The History of Neuroscience in Autobiography Volume 2, Edited by Squire, L.R, Academic Press, 350-395, 1999.

[8] a) Awapara, J. Detection and identification of metabolites in tissues by means of paper chromatography. Federation Procedings, 9:148, 1950. b) Awapara, J., Landua, A.J., Fuerst, R., and Seale, B. Free gamma-aminobutyric acid in brain. Journal of Biological Chemistry 187:35-9, 1950.

[9] Roberts E. Formation and utilization of γ-aminobutyric acid in brain. Edited by Korey S.R., and Nurnberger J.I., Progress in neurobiology. 1. Neurochemistry. New York: Hoeber-Harper, 1956;11-25.

[10] Eccles, J.C., The Synapse: From electrical to Chemical transmission, Annual Review of Neuroscience, 5:325-39, 1982.

[11] For overview see Florey, E., GABA: history and perspectives, Canadian Journal of Physiology and Pharamcology, 69(7):1049-56, 1991.

[12] Bazemore, A.W., Elliott, K.A.C., Florey, E., Isolation of Factor I, Journal of Neurochemistry, 1:334-9, 1957.

[13] Johnston, G.A.R, GABA Australis, some reflections on the history of GABA receptor research in Australia, Pharmacological Research, article in press, 2016.

[14] Bowery, N.G, Smart, T.G, GABA and glycine as neurotransmitters: a brief history. British Journal of Pharmacology, 147:109-119, 2006. And references therein.

[15] a) Krnjević, K. & Schwartz, S. Is γ-aminobutyric acid an inhibitory transmitter? Nature, 211:1372, 1966. b) Krnjević, K. & Schwartz, S. The action of γ-aminobutyric acid on cortical neurones. Experimental Brain Research, 3, 320–326, 1967.

[16] Curtis, D.R., Duggan, A.W., Felix, D., Johnston, G.A.R., GABA, Bicuculline and central inhibition., Nature, 226:1222-1225, 1970.

[17] Roberts, E., γ-aminobutyric acid and nervous system function – a perspective, Biochemical Pharmacology, 23:2637-2649, 1974.

[18] GABA in the Nervous System: The view at Fifty Years, Edited by Martin, D.L and Olsen, R.W., Lippincott Williams & Wilkins, 2000.

[19] Accessed Jan 2017.