Lisa Porter - Academia.edu (original) (raw)

Papers by Lisa Porter

Scientific reports, Mar 25, 2024

COVID-19 has been a global public health and economic challenge. Screening for the SARS-CoV-2 vir... more COVID-19 has been a global public health and economic challenge. Screening for the SARS-CoV-2 virus has been a key part of disease mitigation while the world continues to move forward, and lessons learned will benefit disease detection beyond COVID-19. Saliva specimen collection offers a less invasive, time-and cost-effective alternative to standard nasopharyngeal swabs. We optimized two different methods of saliva sample processing for RT-qPCR testing. Two methods were optimized to provide two cost-efficient ways to do testing for a minimum of four samples by pooling in a 2.0 mL tube and decrease the need for more highly trained personnel. Acid-pH-based RNA extraction method can be done without the need for expensive kits. Direct Lysis is a quick one-step reaction that can be applied quickly. Our optimized Acid-pH and Direct Lysis protocols are reliable and reproducible, detecting the beta-2 microglobulin (B2M) mRNA in saliva as an internal control from 97 to 96.7% of samples, respectively. The cycle threshold (Ct) values for B2M were significantly higher in the Direct Lysis protocol than in the Acid-pH protocol. The limit of detection for N1 gene was higher in Direct Lysis at ≤ 5 copies/μL than Acid-pH. Saliva samples collected over the course of several days from two COVID-positive individuals demonstrated Ct values for N1 that were consistently higher from Direct Lysis compared to Acid-pH. Collectively, this work supports that each of these techniques can be used to screen for SARS-CoV-2 in saliva for a cost-effective screening platform. As of September 2023, the COVID-19 pandemic was still a reality with the SARS-CoV-2 Omicron variant and subvariants circulating throughout both vaccinated and unvaccinated populations 1,2. The virus continued to mutate and spread, all while many countries relaxed most, if not all, their COVID-19 public health measures. The need for effective testing methods was a key concern throughout the pandemic, and rapid detection methods were an important tool in the prevention of outbreaks by identifying positive individuals and removing them from the population. The speed and accuracy of detection are particularly important in protecting high-risk populations, such as residents of long-term care/retirement homes and immunocompromised individuals. In other areas, such as university campuses and amongst high-performance athletes (e.g. National Basketball Association, National Hockey League), rapid testing methods were used to effectively control the spread of COVID-19, preventing further death and long-term illness in communities 3-5. Screening methods can also play an important role in preventing study or work disruptions, thereby protecting global economies. When combined with populationbased surveillance, such as wastewater-based virus detection, rapid screening of individuals can be a powerful platform in protecting society from the devastating consequences of pandemics like COVID-19 6-8 .

bioRxiv (Cold Spring Harbor Laboratory), Mar 13, 2024

Loss of Spy1 decreases tumourigenic potential of triple negative breast cancer Conflict of Intere... more Loss of Spy1 decreases tumourigenic potential of triple negative breast cancer Conflict of Interest: The authors declare no potential conflicts of interest.

bioRxiv (Cold Spring Harbor Laboratory), Mar 11, 2024

Glioblastoma is an aggressive brain tumour associated with high post-therapy recurrence and very ... more Glioblastoma is an aggressive brain tumour associated with high post-therapy recurrence and very poor survival rates. One of the factors contributing to the aggressive nature of this disease is the level of heterogeneity seen at the phenotypic and genetic level. Glioma Stem Cells (GSCs) are stem-like cells within the tumour with the ability to self-renew and give rise to different types of cells within the tumour, hence giving rise to the heterogeneity found in glioblastoma. GSCs are often implicated in the resistance of glioma to standard of care radiation and chemotherapy. The physical niche within a tumour mass supports stemness and aggressive characteristics of GSCs, hence, experimental systems providing a relevant tumour microenvironment are critical for adequate assessment of molecular mechanisms regulating GSC populations. Although, mouse models are a staple of an in vivo experimental design, they are neither time-nor cost-efficient. Danio rerio (zebrafish) patient-derived xenografts (PDXs) overcome several of the obstacles of the mammalian systems. Zebrafish constitute a high throughput, easily reproducible experimental platform allowing for life relevant investigation into the aggressiveness of GSC populations. This chapter describes methods required for generation of zebrafish PDXs to study aspects of GSC-mediated tumorigenesis and interactions with the tumour microenvironment. Consistency between labs for these experiments is required to move the discovery of effective treatments for glioblastoma moving forward.

bioRxiv (Cold Spring Harbor Laboratory), Mar 8, 2024

Background: The cell cycle of mammary stem cells must be tightly regulated to ensure normal homeo... more Background: The cell cycle of mammary stem cells must be tightly regulated to ensure normal homeostasis of the mammary gland to prevent abnormal proliferation and susceptibility to tumorigenesis. The atypical cell cycle regulator, Spy1 can override cell cycle checkpoints, including those activated by the tumour suppressor p53 which mediates mammary stem cell homeostasis. Spy1 has also been shown to promote expansion of select stem cell populations in other developmental systems. Spy1 protein is elevated during proliferative stages of mammary gland development, is found at higher levels in human breast cancers, and promotes susceptibility to mammary tumourigenesis when combined with loss of p53. We hypothesized that Spy1 cooperates with loss of p53 to increase susceptibility to tumour initiation due to changes in susceptible mammary stem cell populations during development and drives the formation of more aggressive stem like tumours. Methods: Using a transgenic mouse model driving expression of Spy1 within the mammary gland, mammary development and stemness were assessed. These mice were intercrossed with p53 null mice to study the tumourigenic properties of Spy1 driven p53 null tumours, as well as global changes in signaling via RNA sequencing analysis. Results: We show that elevated levels of Spy1 leads to expansion of mammary stem cells, even in the presence of p53, and an increase in mammary tumour formation. Spy1-driven tumours have an increased cancer stem cell population, decreased checkpoint signaling, and demonstrate an increase in therapy resistance. Loss of Spy1 decreases tumor onset and reduces the cancer stem cell population. Conclusions: This data demonstrates the potential of Spy1 to expand mammary stem cell populations and contribute to the initiation and progression of aggressive, drug resistant breast cancers with increased cancer stem cell populations.

Cyclin-dependent kinases (CDKs) play a key role in activating essential cell biology processes in... more Cyclin-dependent kinases (CDKs) play a key role in activating essential cell biology processes including cellular proliferation. Inappropriate regulation of CDKs has been implicated in driving several different forms of cancer. One of the regulatory factors is the need to bind to Cyclin-partners before they can be activated and advance the cell cycle. Cyclins are overexpressed in several different cancers, hence activating their relevant CDK. Hyperactive CDK2 in particular is implicated in many cancers, and while many drugs have shown preclinical promise, none have successfully passed through clinical development. Among the complications of targeting CDK2 is the fact that non-classical cyclin partners from the Speedy/RINGO family of proteins can alter the conformation of the kinase. Using computational approaches, we provide data supporting that the active site of CDK2 differs when bound to Spy1 as compared to classical cyclins. Furthermore, combining computational models with experimental techniques we provide data that many small molecule inhibitors have reduced activity against Spy1-bound CDKs. This work supports the need to develop new inhibitors capable of inhibiting the Spy1-CDK2 complex, and suggests that computational tools can be beneficial toward accomplishing this goal.

PLOS ONE

Glucocorticoids, such as dexamethasone (Dex), are used to prevent common side effects induced by ... more Glucocorticoids, such as dexamethasone (Dex), are used to prevent common side effects induced by chemotherapy and are heavily prescribed for solid cancers such as breast cancer. There is substantial pre-clinical data to support that Dex activation of the glucocorticoid receptor overrides chemotherapy-induced apoptosis in breast cancer cell lines. These findings are compounded by a recent study demonstrating that increased glucocorticoid receptor activation by endogenous stress hormones increased breast cancer heterogeneity and metastasis. Our study is the first to use both in vitro and in vivo models to thoroughly compare the Dex response on the migration of multiple estrogen receptor negative (ER-) and ER+ cancer cell lines. ER+ and ER- breast cancer cell lines were studied to compare their endogenous glucocorticoid activity as well as their metastatic ability in response to Dex treatment. We show that in the ER- breast cancer lines, Dex increases cell numbers, invasiveness, and mi...

PLOS ONE, 2022

The objective of this study was to characterize commercially-available cotton fabrics to determin... more The objective of this study was to characterize commercially-available cotton fabrics to determine their suitability as materials for construction of cloth masks for personal and public use to reduce infectious disease spread. The study focused on cottons because of their widespread availability, moderate performance and they are recommended for inclusion in home-made masks by international health authorities. Fifty-two cottons were analyzed by electron microscopy to determine fabric characteristics and fabric weights. Sixteen fabrics were selected to test for breathability and to construct 2-ply cotton masks of a standard design to use in quantitative fit testing on a human participant. Cotton mask fitted filtration efficiencies (FFEs) for 0.02–1 μm ambient and aerosolized sodium chloride particles ranged from 40 to 66% compared with the mean medical mask FFE of 55±2%. Pressure differentials across 2-ply materials ranged from 0.57 to > 12 mm H2O/cm2 on samples of equal surface a...

A wastewater surveillance program targeting a university residence hall was implemented during th... more A wastewater surveillance program targeting a university residence hall was implemented during the spring semester 2021 as a proactive measure to avoid an outbreak of COVID-19 on campus. Over a period of 7 weeks from early February through late March 2021, wastewater originating from the residence hall was collected as grab samples 3 times per week. During this time, there was no detection of SARS-CoV-2 by RT-qPCR in the residence hall wastewater stream. Aiming to obtain a sample more representative of the residence hall community, a decision was made to use passive samplers beginning in late March onwards. Adopting a Moore Swab approach, SARS-CoV-2 was detected in wastewater samples on just two days after passive samplers were activated. These samples were also positive for the B.1.1.7 (Alpha) Variant of Concern (VOC) by RT-qPCR. The positive result triggered a public health case finding response including a mobile testing unit deployed to the residence hall the following day with ...

ABSTRACTTuberin is a member of a large protein complex, Tuberous Sclerosis Complex, and acts as a... more ABSTRACTTuberin is a member of a large protein complex, Tuberous Sclerosis Complex, and acts as a sensor for nutrient status regulating protein synthesis and cell cycle progression. Mutations in the Tuberin gene, TSC2, lead to the formation of tumors and developmental defects in many organ systems, including the central nervous system. Tuberin is expressed in the brain throughout development and levels of Tuberin have been found to decrease during neuronal differentiation in cell lines in vitro. Our current work investigates the levels of Tuberin at two stages of embryonic development in vivo, and we study the mRNA and protein levels during a time course using immortalized cell lines in vitro. Our results show that Tuberin levels remain stable in the olfactory bulb but decrease in the Purkinje cell layer during embryonic mouse brain development. We show here that Tuberin levels are higher when cells are cultured as neurospheres, and knockdown of Tuberin results in a reduction in the...

bioRxiv (Cold Spring Harbor Laboratory), Dec 24, 2023

Purposec-Myc is frequently upregulated in breast cancers, however, targeting c-Myc has proven to ... more Purposec-Myc is frequently upregulated in breast cancers, however, targeting c-Myc has proven to be a challenge. Targeting of downstream mediators of c-Myc, such as the ‘cyclin-like’ cell cycle regulator Spy1, may be a viable therapeutic option in a subset of breast cancer subtypes.MethodsMouse mammary tumour cells isolated from MMTV-Myc mice and human breast cancer cell lines were used to manipulate Spy1 levels followed by tamoxifen or chemotherapeutic treatment with a variety of endpoints. Patient samples from TNBC patients were obtained and constructed into a TMA and stained for c-Myc and Spy1 protein levels.ResultsOver time, MMTV-Myc cells show a decreased response to tamoxifen treatment with increasing levels of Spy1 in the tamoxifen-resistant cells. shRNA against Spy1 re-establishes tamoxifen sensitivity. Spy1 was found to be highly elevated in human TNBC cell and patient samples, correlating to c-Myc protein levels. c-Myc was found to be stabilized by Spy1 and knocking down S...

Frontiers in Cell and Developmental Biology

The ability of cells to sense diverse environmental signals, including nutrient availability and ... more The ability of cells to sense diverse environmental signals, including nutrient availability and conditions of stress, is critical for both prokaryotes and eukaryotes to mount an appropriate physiological response. While there is a great deal known about the different biochemical pathways that can detect and relay information from the environment, how these signals are integrated to control progression through the cell cycle is still an expanding area of research. Over the past three decades the proteins Tuberin, Hamartin and TBC1D7 have emerged as a large protein complex called the Tuberous Sclerosis Complex. This complex can integrate a wide variety of environmental signals to control a host of cell biology events including protein synthesis, cell cycle, protein transport, cell adhesion, autophagy, and cell growth. Worldwide efforts have revealed many molecular pathways which alter Tuberin post-translationally to convey messages to these important pathways, with most of the focus ...

American journal of biomedical sciences, Oct 1, 2011

Barrier materials used in medical gloves and condoms to prevent the penetration of infectious age... more Barrier materials used in medical gloves and condoms to prevent the penetration of infectious agents are of utmost importance for the preservation of public health. Surrogate viruses have proven effective as conservative measures of infectious potential. Previous work has tested the integrity of barrier materials exposed to a host of pressures and stresses, however none have tested the effects of pH exposure mimicking that prevailing through coitus. We optimized the use of bacteriophage ФX174 and PCR detection to conduct a pilot study on the effects of pH on the viral penetration of latex condoms. Our results suggest that exposure of condoms to acidic pH ranges of physiological significance increases the frequency of condom failure rate. This proof of principal work supports the need for a larger study to investigate the significance of these effects over a wide range of condom brands.

6-alkoxy-2-aminopurine derivatives are potent inhibitors of Cyclin Dependent Kinases (CDKs), with... more 6-alkoxy-2-aminopurine derivatives are potent inhibitors of Cyclin Dependent Kinases (CDKs), with some selectivity towards CDK2 and thus have potential as cancer therapeutics. Development of these inhibitors for targeting CDK2-cyclin A/E complexes has previously involved a thorough investigation of structure activity relationships of the C 2 amine moiety. However, the established synthesis of these compounds, which uses the alcohol reagent as solvent, limits the complexity of the O 6 functionality which is required for more selective targeting. Herein we report an improved and refocused synthesis of a model CDK2 inhibitor (NU6247), affording convenient access to inhibitors with O 6 substituents whose parent alcohol is not amenable for use as solvent. This revised synthesis allows for a meaningful exploration of the O 6 position in this class of CDK2 inhibitors.