Biology subjects

Gordon, P. M.

Publications and source records attributed to Gordon, P. M..

9 recordsLinked to original sources

bioRxiv2026

ABCB1-Mediated Drug Efflux Drives Resistance to VpreB1-Targeted Antibody-Drug Conjugates in B-cell Lymphoblastic Leukemia

Although B-cell acute lymphoblastic leukemia (B-ALL) is highly responsive to antigen-directed immunotherapies, treatment resistance remains a major barrier to achieving durable responses in patients. We recently developed a novel VpreB1 (CD179a)-directed antibody-drug conjugate with calicheamicin (VpreB1-ADC) that exploits the restricted expression of VpreB1 within the surrogate light chain in early B cells, including B-ALL. In the present work, we investigated mechanisms of resistance to the VpreB1-ADC. Mechanisms of resistance were evaluated using a TCF3::HLF B-ALL model, assessing target engagement parameters including VpreB1 surface expression and antibody internalization. The role of the multidrug resistance transporter ABCB1 (P-glycoprotein) was evaluated via pharmacologic inhibition, using tariquidar and zosuquidar, and enforced overexpression across multiple B-ALL cell lines. Sensitivity to alternative non-ABCB1 substrate payloads exatecan and PNU-159682 was also assessed. Resistant TCF3::HLF cells retained VpreB1 expression and efficient antibody internalization. Instead, resistance was driven by elevated ABCB1 expression and activity. ABCB1 inhibition with tariquidar or zosuquidar restored VpreB1-ADC sensitivity. Conversely, enforced ABCB1 overexpression conferred ADC resistance, which was reversed by ABCB1 inhibition. Cells with high ABCB1 activity remained fully sensitive to alternative payloads, including exatecan and PNU-159682, which are not ABCB1 substrates. ABCB1-mediated drug efflux drives intrinsic resistance to calicheamicin-conjugated ADCs in B-ALL. Combining ADCs with ABCB1 inhibitors or selecting payloads non-susceptible to ABCB1 efflux offer viable strategies to overcome resistance and optimize future ADC therapies.

cancer biology↗

bioRxiv2025

Engineered lymphatic stroma model applications in central nervous system leukemia

Central nervous system (CNS) involvement frequently occurs in acute lymphoblastic leukemia (ALL), but many questions remain about how leukemia cells access, persist in, and exploit the CNS. The CNS is protected by the meninges, which are fluid filled membranes that surround the brain. Within the meninges, meningeal lymphatic vessels drain cerebrospinal fluid to cervical lymph nodes for immunosurveillance, a potential pathway for leukemia cell migration into or egress from the CNS. Here, we utilize tissue engineered models of the meningeal lymphatics and lymph node stroma to probe how leukemia cells interact with these key tissues. We first demonstrate that standard-of-care chemotherapeutics can damage meningeal lymphatic barriers. Next, we showed that soluble factors from the meningeal lymphatics can support leukemia cell growth while soluble factors from the lymph node model under flow can promote leukemia cell migration. Finally, we show that leukemia cells migrate through the lymph node model under both static and flow conditions. Overall, we have demonstrated the feasibility of using engineered lymphatic models to study leukemia cell behavior in the CNS with the goal of expanding the available experimental platforms for understanding CNS metastasis and relapse. Insight BoxLeukemia commonly infiltrates the central nervous system (CNS), requiring intensive CNS-directed therapies that are often ineffective and cause both acute and long-term toxicities, especially in pediatric patients. The meningeal lymphatics and the deep cervical lymph nodes constitute a pivotal axis in CNS immunity, facilitating drainage of fluid and waste and enabling peripheral immune surveillance in response to CNS-derived signals. Here, we employ in vitro models of the meningeal lymphatics and lymph node stroma to demonstrate their crosstalk in influencing leukemia cell growth and migration. These engineered platforms serve as valuable tools for uncovering mechanistic insights into the meningeal-lymph node axis in the context of CNS-leukemia relapse.

bioengineering↗

bioRxiv2025

Muscle Strength and Size Relationships with Unilateral Progressive Resistance Training

PurposeThis study defines correlative and causal relationships between muscle strength and size before and after unilateral resistance training (RT) in a large cohort of healthy adults, focusing on sex differences within these relationships. MethodsResults from 1233 participants (504 males and 729 females) in a retrospective analysis were included. Maximal voluntary isometric contraction strength (MVC), one-repetition maximum strength (1RM), biceps cross-sectional area (CSA) and elbow flexor volume (VOL) measures of the non-dominant and dominant arm were evaluated from baseline and after 12-wk RT twice per week. Correlations of MVC and VOL and 1RM and VOL were calculated in the whole cohort and within each sex independently. Causal analysis modeling was used to infer mechanistic relationships among variables. ResultsAbsolute muscle strength and size related to one another both at baseline and following training, however correlation strength in each sex were weak. After RT, MVC relative change and VOL relative change correlations were correlated for the whole cohort (r=0.16; p<0.001) and females (r=0.18; p<0.001), but not in males (r=0.11; p=0.07). No significant correlations for relative change in 1RM and VOL were observed for the whole cohort or within sex. Causal discovery determined that change in VOL caused significant change in 1RM (but not MVC) and age was identified as a potential cause. ConclusionsSex differences occur in muscle size and strength relationship adaptations following resistance training, most notably the absence of significant relationships between relative size and strength changes in men. Simpsons paradox bias, where assessing the combined data of males and females (also affecting overall sample size) affects identifies patterns differently than assessing relationships within each sex, may partially explain our findings.

physiology↗

bioRxiv2024

Single-chain nanobody inhibition of Notch and avidity enhancement utilizing the β-pore forming toxin Aerolysin

Notch plays critical roles in developmental processes and disease pathogenesis, which has led to numerous efforts to modulate its function with small molecules and antibodies. Here we present a nanobody inhibitor of Notch signaling, derived from a synthetic phage-display library targeting the notch Negative Regulatory Region (NRR). The nanobody inhibits Notch signaling in a luciferase reporter assay and in Notch-dependent hematopoietic progenitor cell differentiation assay, despite a modest 19uM affinity for Notch. We addressed the low affinity by fusion to a membrane-associating domain derived from the {beta}-Pore forming toxin Aerolysin, resulting in a significantly improved IC50 for Notch inhibition. The nanobody-aerolysin fusion inhibits proliferation of T-ALL cell lines with similar efficacy to other Notch pathway inhibitors. Overall, this study reports the development of a Notch inhibitory antibody, and demonstrates a proof-of-concept for a generalizable strategy to increase the efficacy and potency of low-affinity antibody binders.

biochemistry↗

bioRxiv2023

An expression-directed linear mixed model (edLMM) discovering low-effect genetic variants

Detecting genetic variants with low effect sizes using a moderate sample size is difficult, hindering downstream efforts to learn pathology and estimating heritability. In this work, by utilizing informative weights learned from training genetically predicted gene expression models, we formed an alternative approach to estimate the polygenic term in a linear mixed model (LMM). Our LMM estimates the genetic background by incorporating their relevance to gene expression. Our protocol, expression-directed linear mixed model (edLMM), enables the discovery of subtle signals of low-effect variants using moderate sample size. By applying edLMM to cohorts of around 5,000 individuals with either binary (WTCCC) or quantitative (NFBC1966) traits, we demonstrated its power gain at the low-effect end of the genetic etiology spectrum. In aggregate, the additional low-effect variants detected by edLMM substantially improved estimation of missing heritability. edLMM moves precision medicine forward by accurately detecting the contribution of low-effect genetic variants to human diseases.

genetics↗

bioRxiv2020

Human patient SFPQ homozygous mutation is found deleterious for brain and motor development in a zebrafish model

SFPQ (Splicing factor proline- and glutamine-rich) is a DNA and RNA binding protein involved in transcription, pre-mRNA splicing, and DNA damage repair and it has been previously implicated in neurodegenerative disorders. A homozygous p.Ser660Asn variant in SFPQ was identified through whole exome sequencing (WES) in an Italian woman presented a complex neurological phenotype with intellectual disability, peripheral neuropathy, bradykinesia, extrapyramidal rigidity and rest (heads) tremor and neuroradiological anomalies including thin dysplastic corpus callosum, hypomyelination and hypointensity of the globus pallidus and of the mesencephalic substantia nigra (resembling neurodegeneration with brain iron accumulation; NBIA). Using a zebrafish SFPQ genetic model we have showed that a rescue with this SFPQS660N mutant revealed robust defects in the developing central nervous system (CNS) of the embryos, including abnormal branching of the motor axons innervating body muscles and misfolding of the posterior brain neuroepithelium. The defects hereby identified in the model organism indicate a potential contribution of the homozygous SFPQ p.Ser660Asn variant in some of the patient's neurodegenerative features, including the clinical parkinsonism and the NBIA-like pattern on brain imaging.

neuroscience↗

bioRxiv2019

Disrupting the leukemia niche in the central nervous system attenuates leukemia chemoresistance

Protection from acute lymphoblastic leukemia (ALL) relapse in the central nervous system (CNS) is crucial to survival and quality of life for ALL patients. Current CNS-directed therapies cause significant toxicities and are only partially effective. Moreover, the impact of the CNS microenvironment on leukemia biology is poorly understood. Herein, we showed that leukemia cells associated with the meninges of xenotransplanted mice, or co-cultured with meningeal cells, exhibit enhanced chemoresistance due to effects on both apoptosis balance and quiescence. From a mechanistic standpoint, we identified that leukemia chemoresistance is primarily mediated by direct leukemia-meningeal cell interactions and overcome by detaching the leukemia cells from the meninges. Next, we used a co-culture adhesion assay to identify drugs that disrupted leukemia-meningeal adhesion. In addition to identifying several drugs that inhibit canonical cell adhesion targets we found that Me6TREN, a novel hematopoietic stem cell (HSC) mobilizing compound, also disrupts leukemia-meningeal adhesion in vitro and in vivo. Finally, Me6TREN enhanced the efficacy of cytarabine in treating CNS leukemia in xenotransplanted mice. This work demonstrates that the meninges exert a critical influence on leukemia chemoresistance, elucidates mechanisms of CNS relapse beyond the well-described role of the blood-brain barrier, and identifies novel therapeutic approaches for overcoming chemoresistance.

cancer biology↗

bioRxiv2019

The meninges enhance leukemia survival in cerebral spinal fluid

Central nervous system (CNS) relapse is a common cause of treatment failure in patients with acute lymphoblastic leukemia (ALL) despite current CNS-directed therapies that are also associated with significant short and long-term toxicities. Herein, we showed that leukemia cells exhibit decreased proliferation, elevated reactive oxygen species (ROS), and increased cell death in CSF both in vitro and in vivo. However, interactions between leukemia and meningeal cells mitigated these adverse effects. This work expands our understanding of the pathophysiology of CNS leukemia and suggests novel therapeutic approaches for more effectively targeting leukemia cells in the CNS.

cancer biology↗

bioRxiv2019

A shared core microbiome in soda lakes separated by large distances

In alkaline soda lakes, high concentrations of dissolved carbonates establish an environment favouring productive phototrophic microbial mat communities. Here we show how different species of microbial phototrophs and autotrophs contribute to this exceptional productivity. Four years of amplicon and shotgun DNA sequencing data from microbial mats from four different lakes indicated the presence of over 2,000 different species of Bacteria and Eukaryotes. Metagenome-assembled-genomes were obtained for a core microbiome of <100 abundant bacteria, which was shared among lakes and accounted for half of the extracted DNA throughout the four year sampling period. Most of the associated species were related to similar microbes previously detected in sediments of Central Asian alkaline soda lakes, showing that common selection principles drive community assembly from a globally distributed reservoir of alkaliphile biodiversity. Dispersal events between the two distant lake systems were shown to be extremely rare, with dispersal rates a function of abundance in microbial mats, but not sediments. Detection of more than 7,000 expressed proteins showed how phototrophic populations allocated resources to specific processes and occupied complementary niches. Carbon fixation only proceeded by the Calvin-Benson-Bassham cycle, detected in Cyanobacteria, Alphaproteobacteria, and, suprisingly, Gemmatomonadetes. Our study not only provides new fundamental insight into soda lake ecology, but also provides a template, guiding future efforts to engineer robust and productive biotechnology for carbon dioxide conversion.\n\nImportanceAlkaline soda lakes are among the most productive ecosystems worldwide, despite their high pH. This high productivity leads to growth of thick \"mats\" of filamentous cyanobacteria. Here, we show that such mats have very high biodiversity, but at the same time contain a core, shared set of only approximately 100 different bacteria that perform key functions, such as photosynthesis. This \"core microbiome\" occurs both in Canadian and Central Asian soda lakes, >8,000 km apart. We present evidence for (very rare) dispersion of some core microbiome members from Canadian mats to Central Asian soda lake sediments. The close similarity between distant microbial communities indicates that these communities share common design principles, that reproducibly lead to a high and robust productivity. We unravel a few examples of such principles and speculate that these might be applied to create robust biotechnology for carbon dioxide conversion, to mitigate of global climate change.

microbiology↗