Biology subjects

Wheeler, D. L.

Publications and source records attributed to Wheeler, D. L..

4 recordsLinked to original sources

bioRxiv2026

A Novel Syngeneic Mouse Model to Study Immune Evasion in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide, and patient outcomes have remained largely unchanged despite advances in multimodal therapy. Immune checkpoint inhibitors (ICIs), which block the PD-1/PD-L1 axis to restore T cell-mediated anti-tumor immunity, have emerged as a promising treatment strategy. However, response rates remain below 20% in HNSCC, underscoring the need to better understand mechanisms of immune evasion within the tumor microenvironment. Syngeneic mouse models are essential for studying tumor-immune interactions, yet currently available HNSCC models are limited. Here, we report the development of a novel FVB/NJ-derived syngeneic HNSCC model generated from 7,12-dimethylbenz(a)anthracene (DMBA)-induced primary on floor of mouth/buccal tumors, designated FMOC1, FMOC2, and FMOC3 (FVB/NJ Mouse Oral Cancer). In vitro, all FMOC cell lines exhibited robust proliferative capacity with distinct proliferation kinetics. In vivo, all FMOC cell lines exhibited characteristic HNSCC histopathology, including cytokeratin 5 positivity, and were tumorigenic in immunodeficient NCG mice; however, in syngeneic immunocompetent mice, only FMOC1 demonstrated sustained tumor growth at orthotopic and flank sites, whereas FMOC2 and FMOC3 tumors underwent spontaneous regression within 2 weeks, indicating differential immune-dependent tumorigenicity among the lines. Consistent with this, depletion of CD4+ and/or CD8+ T cells restored tumor growth in FMOC2 and FMOC3 models, indicating a critical role for T cell-mediated immunity in tumor suppression. Notably, FMOC1 tumors were responsive to anti-PD-L1 and anti-CTLA-4 therapy, supporting their utility for evaluating immunotherapeutic strategies. Collectively, these findings establish the FMOC model as a novel and versatile platform to study tumor-immune interactions and immune evasion mechanisms in HNSCC, with potential applications in preclinical immunotherapy development.

cancer biology↗

bioRxiv2022

Turning coldspots into hotspots: targeted recruitment of axis protein Hop1 stimulates meiotic recombination in Saccharomyces cerevisiae

The DNA double strand breaks (DSBs) that initiate meiotic recombination are formed in the context of the meiotic chromosome axis, which in budding yeast contains a meiosis-specific cohesin isoform and the meiosis-specific proteins Hop1 and Red1. Hop1 and Red are important for DSB formation; DSB levels are reduced in their absence and their levels, which vary along the lengths of chromosomes, are positively correlated with DSB levels. How axis protein levels influence DSB formation and recombination remains unclear. To address this question, we developed a novel approach that uses a bacterial ParB-parS partition system to recruit axis proteins at high levels to inserts at recombination coldspots where Hop1 and Red1 levels are normally low. Recruiting Hop1 markedly increased DSBs and homologous recombination at target loci, to levels equivalent to those observed at endogenous recombination hotspots. This local increase in DSBs did not require Red1 or the meiosis-specific cohesin component Rec8, indicating that, of the axis proteins, Hop1 is sufficient to promote DSB formation. However, while most crossovers at endogenous recombination hotspots are formed by the meiosis-specific MutL{gamma} resolvase, only a small fraction of crossovers that formed at an insert locus required MutL{gamma}, regardless of whether or not Hop1 was recruited to that locus. Thus, while local Hop1 levels determine local DSB levels, the recombination pathways that repair these breaks can be determined by other factors, raising the intriguing possibility that different recombination pathways operate in different parts of the genome.

genetics↗

bioRxiv2021

Repeated strand invasion and extensive branch migration are hallmarks of meiotic recombination

Currently favored models for meiotic recombination posit that both noncrossover and crossover recombination are initiated by DNA double strand breaks but form by different mechanisms, noncrossovers by synthesis dependent strand annealing, and crossovers by formation and resolution of double Holliday junctions centered around the break. This dual mechanism hypothesis predicts different hybrid DNA patterns in noncrossover and crossover recombinants. We show that these predictions are not upheld, by mapping with unprecedented resolution, parental strand contributions to recombinants at a model locus. Instead, break repair in both noncrossovers and crossovers involves synthesis-dependent strand annealing, often with multiple rounds of strand invasion. Crossover-specific double Holliday junction formation occurs via processes that involve branch migration as an integral feature and that can be separated from break repair itself. These findings reveal meiotic recombination to be a highly dynamic process and prompt a new view of the relationship between crossover and noncrossover recombination.

genetics↗

bioRxiv2020

The Ephrin receptor A2 and Roundabout Guidance Receptor 1 heterodimer: A potential theranostic for squamous cell carcinomas

Squamous cell carcinomas (SCC) of the lung (LSCC) and head and neck (HNSCC) are very prevalent with poor prognosis and limited treatment options. In both cancer types, Ephrin receptor A2 (EPHA2) is known to be overexpressed and exhibit opposing effects via two distinct signaling mechanisms. While it can inhibit cancer cell survival and migration by ligand-dependent signaling through tyrosine kinase phosphorylation at Y588 and Y772, it can promote tumor progression and cell migration in a ligand-independent manner via phosphorylation at S897. Variable ABnormal morphology (VAB-1) is the C. elegans ortholog of the human ephrin receptor (EPHR) that interacts genetically and biochemically in a dose-dependent manner with the axon guidance receptor, SAX3, the worm ortholog of ROBO. Double mutants of vab-1(EPHR)/sx-3(ROBO) are synthetic lethal, underscoring the interaction between the two signaling pathways which prompted us to investigate their role in SCC. Using biochemical and biophysical techniques, we show that EPHA2 and ROBO1 reside in the same complex and interact physically to form a functional heterodimer in LSCC and HNSCC. Furthermore, we show that treating squamous cells with the SLIT2, ligand of ROBO1, hinders phosphorylation of EPHA2 at S897, and thereby, attenuates cell proliferation. Interestingly, SLIT2 can interact with EPHA2 and attenuate the proliferation of cells that have low ROBO1 expression. Additionally, SLIT2 can act synergistically with the EPHA2 inhibitor, Ensartinib to attenuate cell growth in LSCC and HNSCC cells. Taken together, the data suggest that SLIT2 may serve as a novel therapeutic for LSCC and HNSCC. Here, we propose to stratify patients for treatment with SLIT2 and/or Ensartinib, based on their EPHA2 and ROBO1 expression levels in the diseased tissue. Thus 85% of LSCC cases can be treated with combination of SLIT2+Ensartinib and 55% of HNSCC cases can be treated with either SLIT2 or Ensartinib. Furthermore, EPHA2 and ROBO1 may represent novel theranostics in these two diseases. One sentence summaryHeterodimerization of EPHA2 and ROBO1 receptors attenuates growth of squamous cell carcinomas of the lung and head and neck.

cancer biology↗