Biology subjects

Shawber, C. J.

Publications and source records attributed to Shawber, C. J..

3 recordsLinked to original sources

bioRxiv2025

A Novel Therapeutic Approach: Notch Inhibition Enhances Radiotherapy and Checkpoint Blockade Therapy via Reprogramming of the Tumor Microenvironment

BackgroundHigh-dose radiotherapy (RT) in cancer is immunogenic but also induces an immunosuppressive tumor microenvironment (TME) that limits the efficacy of immune checkpoint inhibitors (ICIs). Overcoming this immunosuppressive barrier is therefore critical to unlocking the full potential of RT-ICI combinations. As Notch signaling regulates tumor microenvironment, we hypothesized that the {gamma}-secretase inhibitor (GSI), AL101, would suppress radiation-induced immunosuppression and enhance antitumor efficacy when combined with RT and anti-PD-1 (aPD-1) therapy. MethodsSyngeneic neuroblastoma (9464D) and triple-negative breast cancer (EO771) tumors were established in C57BL/6, macrophage-depleted C57BL/6 mice, or athymic mice. Mice received 12 Gy RT (day 3), AL101 (6.5 mg/kg daily, day 0-9), and aPD-1 (days 0, 3, 6). Tumors were analyzed by spectral flow cytometry and single-cell RNA sequencing (scRNA-seq), and lung metastases were evaluated histologically. ResultsThe triple combination of RT, aPD-1, and GSI produced durable tumor growth inhibition and significantly prolonged survival in both models, with median survival more than doubled compared to all other treatment groups. Triple therapy also markedly reduced lung metastases in EO771 mice. These effects were abrogated in athymic nude mice and macrophage-depleted immunocompetent mice, consistent with an immune-dependent mechanism. Based on scRNA-seq and spectral flow cytometry analysis, RT alone increased exhausted T cells and immunosuppressive macrophages, while triple therapy reversed these effects, including expansion of activated CD8 T cells, reduction of Tregs and exhausted T cells, restoration of cross-presenting CD103 dendritic cells, and reprogramming of myeloid cells toward a proinflammatory state. ConclusionsGSI remodels the RT-induced immunosuppressive TME and potentiates the efficacy of RT + ICI. GSI combined with RT+aPD-1 reprograms the TME toward an immunostimulatory state and supports GSI as a promising immuno-radiotherapeutic strategy with strong translational potential.

cancer biology↗

bioRxiv2023

Immature myeloid cells are indispensable for intestinal regeneration post irradiation injury

The intestinal epithelium functions both in nutrient absorption and as a barrier, separating the luminal contents from a network of vascular, fibroblastic, and immune cells underneath. Following injury to the intestine, multiple different cell populations cooperate to drive regeneration of the mucosa. Immature myeloid cells (IMCs), marked by histidine decarboxylase (Hdc), participate in regeneration of multiple organs such as the colon and central nervous system. Here, we found that IMCs infiltrate the injured intestine and promote epithelial regeneration and modulate LEC activity. IMCs produce prostaglandin E2 (PGE2), which promotes LEC lymphangiogenesis and upregulation of pro-regenerative factors including RSPO3. Moreover, we found that IMC recruitment into the intestine is driven by invading microbial signals. Accordingly, antibiotic eradication of the intestinal microbiome prior to WB-IR inhibits IMC recruitment, and consequently, intestinal recovery. We propose that IMCs play a critical role in intestinal repair and implicate gut microbes as mediators of intestinal regeneration.

physiology↗

bioRxiv2021

Unique functions for Notch4 in murine embryonic lymphangiogenesis

In mice, embryonic dermal lymphatic development is well-understood and used to study gene functions in lymphangiogenesis. Notch signaling is an evolutionarily conserved pathway that modulates cell fate decisions, which has been shown to both inhibit and promote dermal lymphangiogenesis. Here, we demonstrate distinct roles for Notch4 signaling versus canonical Notch signaling in embryonic dermal lymphangiogenesis. Actively growing embryonic dermal lymphatics expressed NOTCH1, NOTCH4 and DLL4 which correlated with Notch activity. In lymphatic endothelial cells (LECs), DLL4 activation of Notch induced a subset of Notch effectors and lymphatic genes, which were distinctly regulated by Notch1 and Notch4 activation. Treatment of LECs with VEGF-A or VEGF-C upregulated Dll4 transcripts, and differentially and temporally regulated the expression of Notch1 and Hes/Hey genes. Mice nullizygous for Notch4 had an increase in the closure of the lymphangiogenic fronts which correlated with reduced vessel caliber in the maturing lymphatic plexus at E14.5, and reduced branching at E16.5. Activation of Notch4 suppressed LEC migration in a wounding assay significantly more than Notch1, suggesting a dominant role for Notch4 in regulating LEC migration. Unlike Notch4 nulls, inhibition of canonical Notch signaling by expressing a dominant negative form of MAML1 (DNMAML) in Prox1+ LECs led to increased lymphatic density consistent with an increased in LEC proliferation, described for the loss of LEC Notch1. Moreover, loss of Notch4 did not affect LEC canonical Notch signaling. Thus, we propose that Notch4 signaling and canonical Notch signaling have distinct functions in the coordination of embryonic dermal lymphangiogenesis.

developmental biology↗