ABSTRACT
The transcription factor GATA3 is the master regulator that drives mammary luminal epithelial cell differentiation and maintains mammary gland homeostasis. Loss of GATA3 is associated with aggressive breast cancer development. We have identified ZNF503/ZEPPO2 zinc-finger elbow-related proline domain protein 2 (ZPO2) as a transcriptional repressor of GATA3 expression and transcriptional activity that induces mammary epithelial cell proliferation and breast cancer development. We show that ZPO2 is recruited to GATA3 promoter in association with ZBTB32 (Repressor of GATA, ROG) and that ZBTB32 is essential for down-regulation of GATA3 via ZPO2. Through this modulation of GATA3 activity, ZPO2 promotes aggressive breast cancer development. Our data provide insight into a mechanism of GATA3 regulation, and identify ZPO2 as a possible candidate gene for future diagnostic and therapeutic strategies.
Subject(s)
Breast Neoplasms/genetics , Breast Neoplasms/metabolism , GATA3 Transcription Factor/genetics , Gene Expression Regulation, Neoplastic , Animals , Binding Sites , Biopsy , Breast Neoplasms/pathology , Cell Line , Cell Line, Tumor , Chromatin Immunoprecipitation , Cluster Analysis , Disease Models, Animal , Disease Progression , Epithelial Cells/metabolism , Female , Gene Expression Profiling , Heterografts , High-Throughput Nucleotide Sequencing , Humans , Mice , Neoplasm Metastasis , Promoter Regions, Genetic , Protein BindingABSTRACT
The tumor microenvironment of brain metastases has become a focus in the development of immunotherapeutic drugs. However, countless brain metastasis patients have not experienced clinical benefit. Thus, understanding the immune cell composition within brain metastases, and how the immune cells interact with each other and other microenvironmental cell types, may be critical for optimizing immunotherapy. We applied spatial whole transcriptomic profiling with extensive multiregional sampling (19-30 regions per sample) and multiplex immunohistochemistry on formalin-fixed, paraffin-embedded lung cancer brain metastasis samples. We performed deconvolution of gene expression data to infer the abundances of immune cell populations and inferred spatial relationships from the multiplex immunohistochemistry data. We also described cytokine networks between immune and tumor cells and used a protein language model to predict drug-target interactions. Finally, we performed deconvolution of bulk RNA data to assess the prognostic significance of immune-metastatic tumor cellular networks. We show that immune cell infiltration has a negative prognostic role in lung cancer brain metastases. Our in-depth multiomics analyses further reveal recurring intratumoral immune heterogeneity and the segregation of myeloid and lymphoid cells into distinct compartments that may be influenced by distinct cytokine networks. By employing computational modeling, we identify drugs that may target genes expressed in both tumor core and regions bordering immune infiltrates. Finally, we illustrate the potential negative prognostic role of our immune-metastatic tumor cellular networks. Our findings advocate for a paradigm shift from focusing on individual genes or cell types, towards targeting networks of immune and tumor cells.
ABSTRACT
Bispecific T-cell engager (BiTE) molecules are biologic T cell-directing immunotherapies. Blinatumomab is approved for treatment of B-cell malignancies, but BiTE molecule development in solid tumors has been more challenging. Here, we employed intravital imaging to characterize exposure and pharmacodynamic response of an anti-muCD3/anti-huEGFRvIII mouse surrogate BiTE molecule in EGFR variant III (EGFRvIII)-positive breast tumors implanted within immunocompetent mice. Our study revealed heterogeneous temporal and spatial dynamics of BiTE molecule extravasation into solid tumors, highlighting physical barriers to BiTE molecule function. We also discovered that high, homogeneous EGFRvIII expression on cancer cells was necessary for a BiTE molecule to efficiently clear tumors. In addition, we found that resident tumor-infiltrating lymphocytes (TIL) were sufficient for optimal tumor killing only at high BiTE molecule dosage, whereas inclusion of peripheral T-cell recruitment was synergistic at moderate to low dosages. We report that deletion of stimulatory conventional type I DCs (cDC1) diminished BiTE molecule-induced T-cell activation and tumor clearance, suggesting that in situ antigen-presenting cell (APC) engagements modulate the extent of BiTE molecule efficacy. In summary, our work identified multiple requirements for optimal BiTE molecule efficacy in solid tumors, providing insights that could be harnessed for solid cancer immunotherapy development.