Identification and elucidation of the roles of methylarginine-containing proteins in stress and aging in Saccharomyces cerevisiae
Adam Frankel, Jennifer Brown
Investigators
Summary
Organisms depend on nutrients to grow and proliferate, but the availability of such resources can be limiting at times. This situation represents a stress on a cellular level. The response to this type of stress is studied in the unicellular organism Saccharomyces cerevisiae (baker’s yeast). Research has emerged that cells experiencing nutrient deprivation undergo significant changes to ensure their longterm survival through the winter of their discontent. Under these conditions, cells break down and recycle their components within a vacuole compartment in a process called autophagy, which is necessary for extending the lifespan of the organism. The amino acid arginine is stored in the vacuole and used as one of many protein building blocks. My laboratory studies a methyltransferase enzyme family that attaches small carbon units to the ends of arginine within proteins to form monomethylarginine (MMA) or dimethylarginine (DMA). These simple modifications exert profound cellular effects by altering molecular interactions. The project investigates how the methylated arginine metabolites from autophagy affect cell survival and lifespan. In our investigation into the yeast response to nutrient deprivation, we found significant changes on methylated arginine outside of cells that was dependent on which gene was deleted. We plan to show that this amino acid efflux is a product of autophagy, and that preventing methylated arginine efflux from yeast under stress compromises important processes required for longterm survival. We will search for and characterize new arginine methyltransferases in yeast whose gene deletions impact the efflux of specific methylarginine species. Our findings in yeast will have broad implications for understanding regulatory factors that affect eukaryotic cell survival.
Development of small-molecule inhibitors against protein arginine N-methyltransferase 2
Adam Frankel, Michael Rowley
Investigators
Adam Frankel, Michael Rowley
Summary
Arginine methylation is a prevalent post-translation in biology that facilitates the activities of proteins in regulating gene transcription. Frequently in cancer and other disease phenotypes, proteins can be hypermethylated, resulting in the deregulation of gene transcription and decreased expression of tumor suppressors, leading to uncontrolled cell growth and/or division. Protein arginine N-methyltransferases (PRMTs) are the enzymes responsible for arginine methylation and have emerged as targets for inhibition in specific diseased states. It has been demonstrated that curtailing the activity of PRMTs can reduce the malevolent phenotype of various forms of cancer. In particular, several groups have developed small molecule inhibitors to this end, many of which are in clinical trial stages. PRMT2 has largely been neglected due to its lackluster in vitro kinetics despite being a prominent therapeutic target for specific cancers including aggressive brain tumours. This research seeks to establish a target engagement assay against human PRMT2 to be used in our effort to develop inhibitors capable of arresting cancer cell growth.
Drug delivery to the lungs and tumors with embolizing microspheres
Urs Häfeli
Investigator
Summary
Intravenously injected microspheres of 12 μm will reach the lungs and then get stuck in the capillaries, where they can release drugs (e.g., antimicrobial drugs, anticancer drugs) while slowly degrading. This project is about making drug releasing microspheres of the appropriate size, measuring the release kinetics, and quantifying the drug that reach the target area and induce a treatment response.
Pharmaco-kinetics and -dynamics of radiolabeled biopharmaceuticals measured by SPECT and PET
Urs Häfeli
Investigator
Summary
Evaluation of drug exposure (pharmacokinetics, PK) and response (pharmaco-dynamics, PD) is critical to select appropriate molecules, assess safety and efficacy of drug candidates, and design optimal dosing strategies. PK for biopharmaceuticals can be determined by imaging techniques like PET and SPECT, and yields fully quantitative biodistribution and kinetic data. Biopharmaceuticals in this project can include antibodies, peptides, metal-binding small molecules and nanoparticles.
Next Generation Therapies for Severe Monogenic Diseases
Sarah Hedtrich
Summary
Monogenic diseases of human epithelia such as autosomal recessive congenital ichthyosis (ARCI) mainly affecting the skin or cystic fibrosis (CF; affecting the lung) are monogenic diseases. A correction of which would mitigate the disease. Indeed, for recessively inherited conditions such as ARCI and CF, correction in even a small percentage of disease-affected cells should be therapeutic. Recent advances, particularly the rise of CRISPR/Cas9 technology, have greatly improved the efficacy, fidelity and cost of gene editing. However, efficient delivery of the components of CRISPR/Cas9 to their target site is a major bottleneck especially when it comes to human epithelia. Currently, the Hedtrich lab is actively exploring the feasibility of an in-situ gene therapy for human epithelia.
Development of the Solvent-Assisted Active Loading Technology (SALT) for Liposomal Loading of Poorly Water-Soluble Compounds
Shyh-Dar Li
Investigator
Summary
A large proportion of pharmaceutical compounds exhibit poor water solubility, impacting their delivery. These compounds can be passively encapsulated in the lipid bilayer of liposomes to improve their water solubility, but the loading capacity and stability are poor, leading to burst drug leakage. The solvent-assisted active loading technology (SALT) was developed to promote active loading of poorly soluble drugs in the liposomal core to improve the encapsulation efficiency and formulation stability. By adding a small volume (~5 vol%) of a water miscible solvent to the liposomal loading mixture, we achieved complete, rapid loading of a range of poorly soluble compounds and attained a high drug-to-lipid ratio with stable drug retention. This led to improvements in the circulation half-life, tolerability, and efficacy profiles. The Li lab is utilizing this robust and versatile platform to improve drug solubility and targeting for cancer chemotherapy, cancer immunotherapy, and developing child-friendly oral formulations.
A Carboxymethylcellulose-PEG Conjugate Platform for Delivery of Insoluble Cytotoxic Agents to Tumors
Shyh-Dar Li
Investigator
Summary
Cytotoxic chemotherapeutic agents are used as the standard therapy for a range of significant cancers, but many of these drugs suffer from poor water solubility and low selectivity, limiting their clinical efficacy. To overcome these shortcomings, Cellax™ drug delivery platform was developed. Cellax™ is a polymer-based nanoparticle drug delivery system designed to solubilize hydrophobic drugs and target them to solid tumors, thereby enhancing the efficacy and reducing the side effects. Cellax-docetaxel (Cellax-DTX) displayed improved pharmacokinetic, safety, and efficacy profiles compared to native DTX (Taxotere®) and Nab-paclitaxel (Nab-PTX, Abraxane®) in multiple animal models. Cellax-DTX was shown to interact with serum albumin and SPARC (secreted protein acidic and rich in cysteine) that is highly expressed by tumor stromal cells, leading to superior stroma depleting activity in orthotopic breast and pancreatic tumor models and subsequently reduced incidence of visceral metastases compared to free DTX and Nab-PTX. The Cellax™ platform was employed to deliver podophyllotoxin (Cellax-PPT) and cabazitaxel (Cellax-CBZ), and increased their safety and efficacy against multidrug-resistant tumors. The Li lab is working with their industry partners to commercialize this platform technology.
Developing new assays and inhibitors of Signal Transducer and Activator of Transcription (STAT) proteins
Brent Page
Investigator
Summary
STAT proteins are important signaling molecules that mediate the cellular response to extracellular cytokine or growth factor stimulation. Deregulation of STAT signaling is commonly found in cancer and inflammatory conditions such as rheumatoid arthritis. While many STAT inhibitors have been reported, primarily focusing on STAT3 inhibitors as anti-cancer agents, our recently developed assays have shown that many of these compounds do not directly bind to STAT proteins in cells, and instead may bind to upstream regulators of STATs. We are now using these same assays to develop novel STAT1 and STAT3 inhibitors and are optimizing compounds that were identified from recent high-throughput screening campaigns.
Exploiting the anti-cancer activity of Pyrimethamine analogues
Brent Page, Adam Frankel
Investigators
Summary
Pyrimethamine is a clinically approved anti-malaria drug that was recently discovered to inhibit STAT3 activity in cancer cells and induce promising anti-cancer activity. In the malaria parasite, pyrimethamine binds to dihydrofolate reductase (DHFR), however, this was not initially suspected to be the target for pyrimethamine in cancer cells. Recent work by our group has confirmed that DHFR is the primary target for pyrimethamine in human cells and we are working closely with the David Frank Laboratory at the Dana-Farber Cancer Institute to decipher the link between DHFR and STAT3 inhibition. Ongoing efforts in our lab aim to optimize the activity of new DHFR inhibitors that we hope further develop into promising anti-cancer agents.
Translating the immune glyco-code
Simon Wisnovsky
Investigator
Summary
Prof. Wisnovsky's lab studies the cell surface glycome, a dense network of sugar molecules that coats the surface of every living cell. The glycome plays a fundamental role in regulating the activity of our immune system, helping immune cells to distinguish normal, healthy cells from abnormal cells and invading pathogens. In diseases like cancer, the structure of the cell-surface glycome becomes profoundly altered, allowing tumour cells to escape immune detection. Prof. Wisnovsky's group applies cutting-edge CRISPR genomic screening technologies to better understand the complex genetic mechanisms that regulate these changes in cellular glycosylation. The overarching goal of his research is to identify druggable pathways that can be targeted to modulate the cell-surface glycome, generating new therapeutic options for the treatment of cancer and autoimmune disease.
New technologies for glycome-wide screening
Hundreds of distinct carbohydrate structures (glycans) are attached to thousands of different protein scaffolds on the cell surface. The Wisnovsky lab is building new CRISPR-based technologies that will allow us to directly screen the function of these glycans in a pooled, high-throughput manner. We hope these tools will create new opportunities in translational glycoscience.
