Year: 2017

Preclinical evaluation of gentamicin B1 as treatment for inherited skin fragility disorders caused by nonsense mutations

More than 5,000 rare genetic diseases affect over one million Canadians. Most have no treatment and many patients die in childhood. The small number of patients each of these diseases affects makes it difficult to develop treatments. However, about 10% of cases are due to a nonsense mutation that creates a premature termination codon (PTC); the protein produced is consequently cut short at the mutation and cannot function. 

A potential therapy for this phenomenon is called ‘PTC readthrough,’ which allows the rest of the protein to form, restoring its function. As PTC readthrough is mutation-specific rather than gene-specific or disease-specific, it has the potential to treat many different rare diseases. However, drugs that induce therapeutic levels of PTC readthrough at safe doses are not yet available.

Dr. Roberge’s research has uncovered that gentamicin B1 (B1) potently induces PTC readthrough in tissue culture cells from patients with different rare diseases, making it a promising drug candidate. His lab will take B1 through the next stage of drug development—efficacy testing in cell and animal models—to see if it induces enough normal protein to correct the defect without toxic side effects. For these proof-of-principle studies he will focus on nonsense mutations causing epidermolysis bullosa (EB), a set of devastating, often fatal, skin fragility diseases.

Dr. Roberge has established collaborations with clinicians and researchers specializing in EB to create a collection of patient cells, from which human skin equivalents can be made, treated with B1, and their full-length protein production measured. A successful outcome would justify the activation of a start-up company in British Columbia to develop B1 towards the clinic, potentially working towards improved patient outcomes for many rare diseases.

A novel therapeutic for inflammatory skin diseases

Granzyme B (GzmB), an immune-secreted serine protease, is abundant in skin conditions characterized by excessive inflammation (such as burns, blisters, or scarring) at the hair follicle or at or just under the epidermis, and has been identified as a therapeutic target for autoimmune and chronic skin diseases. 

Studies have defined a role for GzmB at the interface between the outermost (epidermis) and inner (dermis) layers of skin known as the dermal-epidermal junction (DEJ). In fact, many of the key proteins that anchor these two layers together are proteolytic substrates of GzmB. Given that it is well-documented that GzmB accumulates in the DEJ in many autoimmune conditions associated with separation of these layers (e.g. blistering and skin peeling conditions), it is plausible that GzmB-mediated cleavage of such anchoring proteins would contribute to disruption of the DEJ leading to blistering. In support of this concept, when human GzmB is added to freshly obtained human skin, complete separation of the DEJ ensues. 

Dr. Granville has developed a topical first-in-class inhibitor of GzmB and have identified a condition known as Discoid lupus erythematosus (DLE) as our lead indication to enter the clinic. DLE is a rare, autoimmune skin condition that is usually triggered by sunlight. DLE lesions are characterized by DEJ inflammation, scarring, alopecia, and microvascular damage. Importantly, GzmB levels are highly elevated in this form of cutaneous lupus. 

The aim is to obtain first approval of our GzmB inhibitor for DLE followed by subsequent approvals for other skin conditions. This project will generate further proof-of-concept data to support the clinical development and commercialization of a topical GzmB therapeutic for inflammatory skin conditions.

Novel 18F-fluorinated amino acids as oncological PET radiotracers

Positron emission tomography (PET) is a non-invasive imaging technique used to detect tumours and provide information about a patient’s response to treatment. PET generates a 3D image of the inside of a patient’s body and highlights the location of tumors through detection of a radiotracer administered before generating the image. One of the most common forms of radiotracers are small, drug-like molecules containing a radioisotope that bind to or accumulate in cancer cells, precisely locating tumours. 

While many radioisotopes can be used for PET imaging, [18F] is arguably the most desirable due to its high positron output, small atomic size, metabolic stability and worldwide network of production facilities. Despite these advantages, the synthesis of [18F] radiotracers presents many challenges that have limited the scope of radiotracers available for oncological PET imaging. Thus, the majority of oncological PET imaging relies on a single radiotracer: [18F]-FDG, a sugar analogue that preferentially accumulates in cells that have increased metabolism (i.e., cancer cells). 

Unfortunately, [18F]-FDG is not cancer-specific and also tends to bind to other tissues such as brain and bladder, and at sites of inflammation, limiting its utility for detecting tumors in those areas. In recent years there has been considerable interest in identifying complementary radiotracers to FDG, and much attention has focused on the synthesis of 18F-labelled amino acids, which also accumulate in rapidly dividing cancer cells. Dr. Britton’s lab has recently discovered a method for incorporating the [18F] radioisotope into complex drug precursors without the need for elaborate precursor synthesis. 

Dr. Britton aims to:

  • Rapidly expand the number of available amino acid radiotracers using new unique capabilities.
  • Evaluate promising lead radiotracers for oncological PET imaging.
  • Advance selected radiotracers into preclinical animal studies.

In addition to these research aims, Dr. Britton has filed a provisional patent application and will work with the SFU Innovation Office to identify an industrial partner for this new technology. These new amino acid radiotracers could have a profound impact on the early detection of cancer and positively impact the lives of many British Columbians.

Improving whole-genome sequencing as a clinical test for intellectual disability

Intellectual disability (ID) is a life-long affliction that impairs the cognitive functioning and adaptive behavior of affected individuals. About two to three percent of people worldwide suffer from ID. ID is mostly caused by irregularities in the DNA of an individual and is the most common reason for genetic testing. There are thousands of different mutations that we now know can cause ID. Diagnosis is necessary for accurate and effective genetic counselling, however deciphering the underlying genetic component remains a challenge.

The emergence of next-generation sequencing technologies, notably whole-genome sequencing (WGS), has empowered the identification of genetic cause in more than half of all patients with severe ID. WGS allows scanning of the entire genome of an individual for abnormalities in DNA sequence. The number of accurate diagnoses are three to four times higher than what is achievable with current methods. The current major limitation is that WGS fails to detect certain types of mutations.

Dr. Rajan Babu’s research aims to improve the clinical effectiveness of WGS by expanding its detection abilities to include all ID-causing pathogenic mutations, including those that aren’t currently being identified. She will employ an advanced WGS technology and analyze the generated data using three well-optimized bioinformatics pipelines, enhancing the diagnostic sensitivity of WGS.

The results of this research will be incorporated in the standard clinical diagnostic evaluation of patients with ID to promote earlier and definitive diagnosis, and enable optimal clinical care and counselling of affected patients and their families. All patients with clinically actionable finding will be offered genetic counselling and consultation with appropriate medical specialists. Ultimately, Dr. Rajan Babu’s research could facilitate discovery of novel genetic aberrations and refine our understanding of the genes and the biological mechanisms involved in ID as well as reveal new potential targets for therapeutic intervention.

Elucidating the effect of O-GlcNAc modification on protein stability

The glycosylation of proteins with O-GlcNAc is a ubiquitous post-translational modification found throughout the metazoans. Deregulation of O-GlcNAcylation is implicated in several human diseases including type II diabetes, Alzheimer’s disease, and cancer.

 

However, the basic biochemical roles of O-GlcNAcylation remain largely unanswered. Several recent studies have demonstrated a clear link between O-GlcNAc and cellular thermotolerance.

 

It is likely that a basic function of the O-GlcNAc modification prevents the unfolding or aggregation of target proteins. Dr. King will investigate its role in protein stability through series of biochemical and biophysical experiments to probe the effect of O-GlcNAc on protein unfolding, folding, and aggregation. The results of this research will provide important insights into the basic molecular mechanisms governing O-GlcNAc deregulation in human disease.

 

End of Award Update: July 2022

 

Most exciting outputs

The modification of proteins by O-linked N-acetylglucosamine (O-GlcNAc) is a widespread post-translational modification (PTM) that is dysregulated in several human diseases including type II diabetes, Alzheimer’s disease and cancer. However, research progress in this area is hampered by the fact that it is challenging to detect O-GlcNAc on proteins. Further, the basic biochemical roles of O-GlcNAcylation remain largely unanswered.

 

Therefore, we developed a mass spectrometry based method to precisely map sites of O-GlcNAc on proteins. This method employs a UV laser to produce a diversity of O-GlcNAc retained fragment ions, enabling mapping protein modification sites with unprecedented precision.

 

We then explored the role of O-GlcNAc as a biochemical regulator of protein stability. We developed a new high-throughput approach to profile the effect of O-GlcNAc on the thermostability of the proteome. Using this method, we identify several proteins that are regulated by O-GlcNAc. Interestingly, the majority of these proteins display an O-GlcNAc dependent decrease in stability, challenging the prevailing view of O-GlcNAc as being a predominantly stabilizing modification. Thus, we show that O-GlcNAc is a bi-directional regulator of protein stability. We deliver a powerful approach that provides a blueprint for determining the impact of, in principle, any PTM on the thermostability of thousands of proteins in parallel.

 

Impacts so far
This work delivers powerful tools for exploring the role of O-GlcNAc and other labile PTMs as regulators of protein biochemistry.

 

Potential future influence
Decreased levels of protein O-GlcNAcylation is associated with Alzheimer’s disease. However, the basic biochemical mechanisms underlying this association remain unknown. Here we show that O-GlcNAc regulates the stability of several proteins within human cells, a phenomenon that may impact cellular protein levels in Alzheimer’s disease. This fundamental research is important for understanding the impact O-GlcNAc has on protein structure and stability, particularly in the context of its dysregulation in neurodegenerative disorders.

 

Next steps
We plan to continue exploring the influence O-GlcNAc has on protein structure and function. In doing so, we hope to improve our understanding of the fundamental mechanisms underlying neurodegeneration. This research may ultimately provide knowledge that contributes toward the development of new therapeutic strategies.

 

Useful links

Development of improved substrates for live cell imaging to aid in discovering new glucocerebrosidase therapeutic agents

Parkinson’s disease (PD) is a neurodegenerative disorder that affects millions of people worldwide, with no standard treatment currently available. Therefore, there is a major need for new therapeutic agents to treat or prevent the progression of PD. One promising solution involves targeting the protein glucocerebrosidase (GCase) encoded by the gene GBA1. Studies have shown small molecules that increase GCase activity could help prevent the progression of PD.

Dr. Ashmus will use a combination of organic chemistry, chemical biology, and cell biology to discover new therapeutic agents that increase GCase activity. Fluorescently-quenched substrates will be chemically synthesized and used in enzymatic assays to monitor GCase activity in vitro and in neuroblastoma cells. The assay will then be adapted and optimized for use in a high-throughput screen of compounds from the Canadian Glycomics Network and from a natural products collaborator, Roger Linington, at SFU.

The results of this research could produce new lead compounds that increase GCase activity. In addition, the compound screen could aid in identifying new therapeutic targets for PD, which would drive preclinical translation research in this area.

End of Award Update – March 2022

Most exciting outputs

An exciting and successful specific output as part of the project was that we were able to develop a newly designed probe that performs better than the original probe the Vocadlo Lab published and patented back in 2015. The new probe is also capable of being used in a high-throughput screening in live cells. Moreover, the new design led to the development of probes that could for the first-time target other disease-related enzymes of interest in live cells and led to a high-impact publication in Nature Chemical Biology.

Impacts so far

While the main purpose of the research project failed to discover any lead compounds that could be developed as a potential therapeutic agent for Gaucher/Parkinson’s disease, the steps (develop a better probe and optimize use for screening) required to reach the point of running the screen were successful. The data collected (unpublished) has helped secure funding for the Vocadlo Lab and led to collaborations with biotech companies interested in targeting the same enzyme.

Potential future influence

I think some of the work described briefly will start to gain more attention in the next few years. Over the past year or so, I have noticed an increased interest from research institutes and biotech companies in studying enzymes found within the lysosome. This is in part because more of these lysosomal enzymes are being linked to neurological diseases so having biochemical tools that can study them in live cells will be desired. I think some of the probes we have developed over the past couple of years will be of interest to a broader scientific community.

Next steps

The work searching for potential therapeutic agents for Gaucher/Parkinson’s disease is currently ongoing. The majority of my research efforts have shifted to developing and evaluating novel probes targeting other disease-related enzymes. One notable example is a new project collaborating with an expert clinician in Fabry’s Disease. Using one of our recently developed probes, we aim to advance current diagnostic methods and improve dosing and timing of current therapeutics for Fabry Disease patients. I am excited to see some of my work being used in a clinical setting and hope this can lead to something more fruitful in time. Dissemination of the work will be continued through publications, presentations at conferences and through social media platforms.

Useful links

The acute impact of spinal cord injury on cardiac function, and novel hemodynamic management in SCI patients

Following acute spinal cord injury (SCI), one of the only presently available neuroprotective strategies is to try and optimize management of spinal cord blood flow. This treatment specifically aims to immediately increase blood flow to the injured spinal cord tissue to prevent the spread of injury to surrounding spinal cord tissues.
Currently, vasopressors are administered to increase blood pressure to a similar threshold in all patients; however, its efficacy in improving neurological outcomes has not been consistent, and in some patients has been found to actually worsen outcomes. A more optimized and individualized approach to blood flow management in SCI patients is needed.

High-thoracic SCI immediately impairs the brainstem and neural control of the heart. Our pilot data suggest this decentralization of the heart immediately impairs cardiac function, which could have significant implications for the acute management of blood flow in SCI patients. Dr. Williams will investigate the immediate and acute cardiac responses to high-thoracic SCI, and determine whether improvements to cardiac function can improve spinal cord blood flow and neurological outcomes in SCI patients.

Dr. Williams will conduct translational studies utilizing a porcine model of SCI. She will test the efficacy of potential novel management strategies, including restoring cardiac function alone or in combination with vasopressor therapy. A simultaneous study will look at acutely injured individuals with SCI at Vancouver General Hospital, examining heart function during the first three days after injury.

To date, very little work has characterized the impact of SCI on cardiac function in the initial period following injury. Combining invasive and integrative studies in pigs and humans provides us with the unique opportunity to conduct highly translatable studies that could have an immediate impact on SCI patient outcomes.

 

End of Award Update – July 2022

Most exciting outputs
Our research to date has identified how high-level spinal cord injuries (i.e. at or above the mid-back level) impact the heart immediately after the injury occurs. We found that those injuries impact the heart’s output within the first hours post-injury, and further identified a treatment that could harness the heart to support blood pressure and potentially reduce secondary damage to the spinal cord.

 

Impacts so far
The award has allowed us to examine alternative approaches to treating acute spinal cord injury which could ultimately improve outcomes if that approach is effective in the clinical setting. Moreover, as a trainee this award has provided the critical opportunity for me to expand my skillset in the realms of clinical and pre-clinical research, and apply gold-standard techniques to answer questions about the heart that have traditionally been overlooked in the field of spinal cord injury research.

 

Potential future influence
With the support of this award I have made significant strides in my training toward becoming an established cardiovascular researcher. First, it has allowed me to expand my expertise in the heart and its neural control. Second, I have gained invaluable experience in clinical and pre-clinical research, which truly round out my training as a physiologist. Finally, I have been able to produce and output impactful research across those domains and in doing so built strong collaborations with local and international leaders in these respective fields.

 

Next steps
We have yet to publish additional research that has stemmed from this award, looking at the long-term benefits of heart-focused approaches to treating spinal cord injury, and would like to pursue opportunities to implement such an approach in the clinical setting.

 

Useful links

The role of PCSK9 in clearance of bacterial lipids and the development of anti-PCSK9 treatment for sepsis

Sepsis, which is characterized as an uncontrolled inflammatory response to severe infection, is the leading cause of death in intensive care units. In Canada, sepsis led to a total of 13,500 deaths in 2011, which translates to approximately one in 18 deaths in Canada involving sepsis. Despite this pressing medical need, there are currently no effective treatments for sepsis. 

It is well established that bacterial lipids, such as lipopolysaccharide (LPS) in Gram-negative bacteria and lipoteichoic acid (LTA) in Gram-positive bacteria, induce aberrant inflammatory response in sepsis and they associate with various lipoprotein fractions in the blood. Recent research has revealed that septic patients with Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) loss-of-function mutations have better survival rates due to increased bacterial lipid clearance. It is likely that inhibition of PCSK9 leads to enhanced clearance of bacterial lipids and thus an improved chance of survival. 

Dr. Leung will characterize the role of PCSK9 in these two major pathways of bacterial lipid clearance by utilizing a novel in vivo imager to monitor the distribution of fluorescently-tagged LPS and LTA in mice. He will assess the therapeutic potential of PCKS9 inhibition by examining the ability of anti-PCSK9 monoclonal antibodies to clear bacterial lipid-laden LDL and VLDL through the LDLR and VLDLR pathways, respectively. 

Dr. Leung’s research will address a current knowledge gap in the role of lipoprotein pathways in the clearance of inflammatory bacterial lipids from circulation. 

 

Evolutionary determinants of treatment resistant high grade serous ovarian cancer investigated at single cell resolution

Women diagnosed with high grade serous ovarian cancer (HGS) continue to face poor prognosis, with ten-year survival at only 30-40%. Surgical cytoreduction followed by platinum and taxane-based chemotherapy result in clinical remission for a majority of patients. However, up to 80% of patients will suffer relapse because their disease is treatment resistant. Improved outcomes for HGS require both biomarkers of treatment resistance and development of additional treatments targeting tumour cells resistant to first line therapies.

Relapse in HGS is thought to result from the emergence of resistant tumour clones that evolve de-novo or are selected for during treatment. Dr. McPherson will leverage state-of-the-art single cell genome sequencing technologies to study the genomes of treatment naive primary and metastatic HGS samples, in addition to patient derived xenografts subjected to chemotherapeutic agents. His analysis will focus on understanding the genomic changes that confer treatment resistance, and the evolutionary dynamics that produce those changes.

An improved understanding of the mechanisms and dynamics of treatment resistance will result in improved ability to identify patients with relapse potential and provide targeted therapies to improve survival in HGS.

 

The real-world effectiveness of hepatitis C virus (HCV) treatment on decompensated cirrhosis and hospitalizations

Between 230,000 to 450,000 Canadians are infected with hepatitis C virus (HCV). Most of these people were infected decades ago and remained untreated due to the severe side effects and low effectiveness of interferon-based treatment regimens. Therefore, HCV associated liver related morbidity and mortality are now on the rise, with substantial impact on health care utilization. 

Recently, highly effective interferon-free direct acting antiviral (DAA) treatments have started to become available. However, data on real-world effectiveness of DAAs in terms of hospitalization, cirrhosis, decompensation, hepatocellular carcinoma  and mortality is not yet available. 

Dr. Darvishian will address crucial knowledge gaps in the HCV response to DAAs. Specifically, her research will:

  1. Assess the real-world effectiveness of DAA treatments on overall and liver disease-related hospitalizations and the number of hospital admissions.
  2. Assess the real-world effectiveness of DAA treatments in preventing decompensated cirrhosis.
  3. Assess the potential modifying effect of metformin and/or statin on effect of DAAs and their synergestic effects on hospitalizations and decompensated cirrhosis.

The results of this study will be critical for designing an optimal strategy for HCV care and DAA treatment and refining HCV treatment guidelines and strategies.