Biology subjects

Zhang, J. A.

Publications and source records attributed to Zhang, J. A..

4 recordsLinked to original sources

bioRxiv2025

Site-Specific Immune and Stromal Architecture Drive Resistance to Trastuzumab Deruxtecan in HER2+ Metastatic Breast Cancer

Trastuzumab deruxtecan (T-DXd) is an antibody-drug conjugate (ADC) that has demonstrated remarkable efficacy in HER2+ and HER2-low metastatic breast cancer (mBC). Yet, 40-50% of patients fail to respond, and mechanisms underlying resistance, particularly those involving the immune microenvironment, remain poorly understood. To address this gap, we conducted spatial proteomic profiling of metastatic lesions from 25 HER2+ mBC patients treated with T-DXd, using the Bruker GeoMX Digital Spatial Profiler (DSP) platform. Regions of interest (ROIs) were segmented by CD45 expression to distinguish immune-rich versus immune-poor compartments, and spatial marker expression was compared between responders (R) and non-responders (NR). Spearman correlation analysis was used to assess spatial coordination among HER2, fibronectin, and immune markers. Non-responders exhibited greater HER2 heterogeneity, lower CD45+ immune infiltration, and consistent upregulation of fibronectin and granzyme B. In both bone and brain metastases, NR tissues showed strong correlations between fibronectin and T cell markers, indicating spatial immune exclusion. In contrast, NR lymph node metastases displayed negative correlations between fibronectin and immune markers and uncoordinated B-T cell clustering, suggesting an alternative resistance mechanism rooted in immune disorganization rather than exclusion. Collectively, these results implicate HER2 heterogeneity, fibrotic immune exclusion, and immune suppression as key drivers of T-DXd resistance across metastatic sites. By integrating spatial proteomics with clinical outcomes, this study provides novel insights into the spatial immune landscape of ADC resistance and identifies actionable biomarkers for patient stratification and combination therapy design, laying a critical foundation for developing biomarker-guided therapies and personalized treatment strategies to overcome ADC resistance in metastatic breast cancer. Translational SignificanceT-DXd represents a major advance in antibody-drug conjugate (ADC) therapies to address HER2 heterogeneity in tumors through bystander killing. However, treatment options following resistance to T-DXd remain limited, leaving a critical unmet need. As new ADCs continue to emerge, resistance will likely remain a persistent challenge across tumor types. This work extends beyond T-DXd resistance--it provides a framework to address resistance mechanisms common to other ADCs. By investigating immune-mediated mechanisms of ADC resistance, this research identifies therapeutic targets that can be leveraged to develop new treatment strategies. By integrating spatial biology with clinical data, this study offers unprecedented insights into immune-tumor interactions within the resistant tumor microenvironment. This approach deepens mechanistic understanding and enables personalized treatment strategies guided by spatially resolved biomarkers. This novel combination of spatial mechanistic research with clinical data represents advancement toward overcoming ADC resistance and improving outcomes for patients with few therapeutic options.

cancer biology↗

bioRxiv2023

A Highly Efficient Aorta-Gonad-Mesonephros-Like Definitive Hemogenic Endothelium From Human Pluripotent Stem Cells

Summary/AbstractHuman pluripotent stem cells are a tremendous tool to model early human development and disease including their use in the in vitro generation of blood cell fates. Hematopoietic progenitors and stem cells are the primary source of blood and the immune system from early development to adulthood and arise through successive waves of hemogenic mesoderm either in the yolk sac or embryo proper. Researchers have long sought a tractable human model for observing and distinguishing these waves of hematopoiesis in the dish for human developmental and disease modeling. Here we report a high-efficiency method for differentiating human pluripotent stem cells into an aorta-gonad-mesonephros-like definitive hemogenic mesoderm capable of giving rise to definitive hematopoietic progenitor and stem cells. The hematopoietic progenitor and stem cells exhibit robust multilineage in vitro colony forming potential. Gene expression analysis and single cell sequencing strongly support the developmental timing and notion that the pluripotent stem cell derived hematopoietic stem and progenitors are strikingly like bone fide hematopoietic stem cells. The hematopoietic progenitors can be subsequently differentiated into polarized macrophage and T-cells in vitro. Minimal silencing was observed upon differentiation of the pluripotent stem cells to hematopoietic lineages when conducting gene editing. Finally, upon engraftment into immunodeficient animals the hematopoietic progenitors and stem cells differentiate into multiple lineages including B-cells, T-cells, NK-cells, and monocytes.

developmental biology↗

bioRxiv2022

Sex differences in islet stress responses support female beta cell resilience

ObjectivePancreatic {beta} cells play a key role in glucose homeostasis; dysfunction of this critical cell type causes type 2 diabetes (T2D). Emerging evidence points to sex differences in {beta} cells, but few studies have examined male-female differences in {beta} cell stress responses and resilience across multiple contexts, including diabetes. Here, we address the need for high-quality information on sex differences in {beta} cell/islet gene expression and function using both human and rodent samples. MethodsWe compared {beta} cell gene expression and insulin secretion in donors living with T2D to non-diabetic donors in both males and females. In mice, we generated a well-powered islet RNAseq dataset from 20-week-old male and female siblings with equivalent insulin sensitivity. Because on our unbiased analysis of gene expression pointed to sex differences in endoplasmic reticulum (ER) stress response, we subjected islets isolated from age-matched male and female mice to thapsigargin treatment and monitored protein synthesis, cell death, and {beta} cell insulin production and secretion. Transcriptomic and proteomic analyses were used to characterize sex differences in islet responses to ER stress. ResultsOur single-cell analysis of human {beta} cells revealed sex-specific changes to gene expression and function in T2D, correlating with more robust insulin secretion in islets isolated from female donors living with T2D compared to male T2D donors. In mice, RNA sequencing revealed differential enrichment of unfolded protein response pathway-associated genes, where female islets showed higher expression of genes linked with protein synthesis, folding, and processing. This differential expression was biologically significant, as female islets were more resilient to ER stress induction with thapsigargin. Specifically, female islets maintained better insulin secretion and showed a distinct transcriptional response under ER stress compared with males. ConclusionsOur data demonstrate that physiologically significant sex differences in {beta} cell gene expression exist in both humans and mice, and that female {beta} cells maintain better insulin production and secretion across multiple physiological and pathological contexts.

cell biology↗

bioRxiv2018

Single-Cell RNA-seq Reveals a Subpopulation of Cells Underlying β Cell Expansion in the Postnatal Islets

Pancreatic {beta} cells undergo significant expansion and maturation during human and rodent postnatal development. Here, we used single-cell RNA-seq to characterize gene expression patterns at various stages of mouse islet cell development and uncovered a population of cells that is most abundant during the early postnatal period. This cell population lacks expression of FLTP and expresses PDGF receptors. Each of these conditions have previously been associated with proliferative capacity in {beta} cells suggesting that we have identified the proliferative competent of {beta} cell mass expansion. The subpopulation co-express many endocrine lineage-specific genes and exhibits a downregulation of genes associated with mitochondrial oxidative phosphorylation and global protein synthesis. It has upregulated activity of genes in the Wnt, Hippo, PDGF, and Notch pathways and has a significantly higher proliferation potential than the more mature {beta} population. We show that activity of the Notch pathway is required in postnatal {beta} cell expansion where it serves to maintain an undifferentiated endocrine state in the polyhormonal cell population. Collectively, our study identifies a proliferative, progenitor-like cell subpopulation in the postnatal islet as the source of postnatal {beta} cell expansion.

developmental biology↗