LMP student seminars: 15 April
Each week during term time, MSc and PhD candidates in the Department of Laboratory Medicine and Pathobiology present their research.
Anyone is welcome. No need to register.
Location: Medical Sciences Building, rooms 4171 or 4279, see below.
As part of the core research curriculum, students taking LMP1001/2/3: Graduate Seminars in Laboratory Medicine and Pathobiology will present their projects. Please see abstracts below.
3. Cardiovascular, Physiology and Metabolism/ Molecular and Cell Biology and Regenerative Medicine
Location: MSB 4279
Khyati Mittal
- Title: Understanding the Impact of Chronic E-cigarette Aerosol exposure on Airway Epithelial Cell Function
- Supervisor: Dr. Theo Moraes
Paola Driza
- Title: TBA
- Supervisor: TBA
2. Cancer, Development and Aging
Location: MSB 4171
SKB
- Title: YAP/TAZ-mediated suppression of chemotherapy-induced antiviral signaling in lung cancer
- Supervisor: Dr. Kelsie Thu
Ryan Gabriel Ripsman
- Title: Integrating cell-free DNA into a Pediatric Precision Oncology Program: A pilot study
- Supervisor: Dr. Adam Shlien
Abstracts
Khyati Mittal: Understanding the Impact of Chronic E-cigarette Aerosol exposure on Airway Epithelial Cell Function
Background: Over the past decade, e-cigarette use, or vaping, has increased exponentially. The base components found in e-liquid are nicotine and the delivery vehicles: propylene glycol (PG) and vegetable glycerol (VG). While initially considered a ‘safe’ alternative to smoking, emerging literature suggests that vaping is not innocuous. However, the impacts of chronic vaping on lung health have not been established. To address this knowledge gap, this study investigated the effects of exposure to aerosolized PG/VG alone and nicotine-containing e-cigarette aerosol in human airway epithelial cells (HNECs).
Methods: Well-differentiated HNECs (n=7) were exposed to aerosolized STLTH containing PG/VG alone or PG/VG±20 mg/mL nicotine using the Vaping Product Exposure System (VaPES), which generates a 6-second puff every 5 minutes for a total of 40 puffs. Exposure occurred for 1-day to study acute response and 7-consecutive days for chronic response.
Results: Cells exposed to both PG/VG and nicotine-containing vapor showed increased ciliary beat frequency. Elevated IL-8 levels were recorded in response to exposure with nicotine-containing vapor but not with PG/VG alone. Increased cytotoxicity was also observed after chronic exposure of 7 days. Membrane fluidity was increased after both acute and chronic exposure to PG/VG alone.
Conclusions: An increase in CBF suggests an increase in mucociliary clearance, a protective measure stimulated by irritant exposure to clear out the airways. Some inflammation was observed in HNECs with chronic exposure to nicotine-containing vapor, especially on Day-3. Increase in cytotoxicity suggests cell death or damage. Lastly, changes in membrane fluidity due to PG/VG suggest that it alters the intracellular membrane and may affect protein function. Results suggest that nicotine might alleviate this effect of PG/VG. Thus, these findings highlight the potential dangers of PG/VG and nicotine exposure during e-cigarette use.
Paola Driza: TBA
TBA
SKB: YAP/TAZ-mediated suppression of chemotherapy-induced antiviral signaling in lung cancer
Introduction: Chemotherapy is widely used to treat lung cancer (LC) and initially induces tumour regressions in most patients; however, chemoresistance inevitably develops. Thus, an improved understanding of the biology driving chemoresistance is needed to enhance chemotherapeutic efficacy in patients. YAP and TAZ are transcriptional regulators whose overactivation is well-documented to promote LC chemoresistance. Interestingly, some chemotherapies induce antiviral signaling in tumours, which contributes to their anti-cancer effects, and recent studies suggest that YAP/TAZ antagonize antiviral immunity by suppressing induction of type I interferons and interferon stimulated genes. Therefore, we aim to test the hypothesis that suppression of antiviral signaling by YAP/TAZ represents a previously unrecognized mechanism of chemoresistance.
Methods: In the lung cancer cell line, H1299, siRNA was used to knockdown YAP and/or TAZ. Cells were then treated for 48h with Cisplatin, Doxorubicin, or Paclitaxel, and Poly(I:C) for 4h as a positive control for inducing antiviral signaling. qPCR was used to measure IFN-β, OASL, CXCL10, CCL5 as readouts of antiviral signaling.
Results: H1299 cells stimulated with Poly(I:C) had a 2-3-fold increase in IFN-β with YAP or TAZ knockdown and a 5-fold increase in IFN-β with combined YAP/TAZ knockdown relative to control siRNA. Induction of OASL, CXCL10 and CCL5 by chemotherapy was greater in cells with YAP or TAZ knockdown and greatest in cells with combined YAP/TAZ knockdown. This confirms that YAP/TAZ suppress IFN-β induction by Poly(I:C) and OASL, CXCL10 and CCL5 induction by chemotherapy, and suggests that YAP/TAZ negatively regulate chemo-induced antiviral signaling which could contribute to chemoresistance.
Ryan Gabriel Ripsman: Integrating cell-free DNA into a Pediatric Precision Oncology Program: A pilot study
Background: Cell-free DNA (cfDNA), DNA found in the plasma, has shown promise as a tool for interrogating the genomic characteristics of tumours without the need for an invasive biopsy or surgery to obtain tumour tissue. Numerous proof-of-principle studies have shown that cfDNA can be used to identify druggable mutations from a patient’s tumour and can be used to reconstruct tumour evolution with unprecedented resolution. However, few precision pediatric oncology programs have fully integrated cfDNA into their workflow. Furthermore, most studies rely on targeted panels of cfDNA rather than high-pass whole genome sequencing (WGS), which allows for more comprehensive analysis of tumour evolution. In this study we developed a workflow for integrating cfDNA into the SickKids Cancer Sequencing precision oncology program (KiCS) and demonstrated the utility of both targeted panels and WGS of cfDNA for precision oncology.
Methods: WGS was performed on 12 cfDNA samples from 11 patients enrolled in the KiCS program at a depth of 60-100x. When available, matching genomic DNA was extracted and underwent WGS at a depth of 30-40x. 5 patients had cfDNA and matched white blood cells sequenced using a targeted panel with over 900 cancer associated genes to a depth of at least 2500x. All patients in the study had both WGS and targeted sequencing performed on at least one tissue tumour sample for comparison. Mutation calling was performed using Mutect2, and Sage and filtered using a custom script. Copy number variations were called using ichorCNA for the WGS data and CNVkit for the targeted panel data. Fusions and other large structural variants were called from the WGS data using GRIDSS. Mutational signatures were fit using SigProfiler to signatures from COSMIC version 3.
Results: cfDNA can be reliably extracted from pediatric patients with relapsed or refractory tumours. Evidence of tumour derived variants were found in 4/12 WGS samples and 4/5 targeted panel samples. New proposed cancer drivers were found in 1/12 WGS samples and 1/5 targeted panels. In one of the patients, a proposed cancer driver was found in a region of the genome not covered by the targeted panel. Overall, mutational signature profiles were similar between cfDNA and patient-matched tissue samples. However, a novel therapy-associated mutational signatures were discovered in one of the patients, indicating that cfDNA may be useful for monitoring changes in mutation etiology, and the development of treatment resistance.
Conclusions: Targeted panels of cfDNA are a useful resource for the discovery and surveillance of driver mutations in pediatric patients. WGS of tumours shows promise for the identification of tumour drivers in regions not covered by the panel as well as for the analysis of tumour development and evolution. A larger retrospective study and the integration of cfDNA into the KiCS program on a prospective basis is warranted based on the results of this study.
Contact
No need to register.
Contact lmp.grad@utoronto.ca with any questions