Project Summary Chengcheng Jin, Ph.D Neutrophils are the most abundant immune cells in human blood. They are multi-functional innate myeloid cells that play key roles in pathogen infection, tissue repair, as well as cancer. As a main composition of the tumor- associated immune cells in multiple cancer types, neutrophils have emerged as a critical player to promote cancer progression via diverse mechanisms, such as mediating tissue remodeling, driving local inflammation, suppressing anti-tumor T cells. However, no viable strategy is currently available to target neutrophils for cancer therapy. This reveals fundamental questions and challenges: are tumor-associated neutrophils (TAN) distinct from normal blood neutrophils? Do all the neutrophils in the TME function identically and carry out the broad range of tumor-promoting activities? Is it possible to selectively target the tumor-promoting neutrophils without impairing those essential for protecting us from bacterial infection? Our vision is to develop an in-depth and broad understanding of transcriptional and epigenetic reprogramming of neutrophils in the tumor microenvironment (TME). This will reveal novel regulatory mechanisms unique to tumor-promoting neutrophils that can serve as targets of precision cancer immunotherapies while preserving immune surveillance in healthy tissues. Our strategy is to take an integrated approach that leverages the unique expertise and knowledge that we have established in genetically engineered mouse models. Specifically, we will (1) combine phenotypic, transcriptional and chromatin profiling of neutrophils in different TME at the single-cell level, (2) apply fate mapping and spatial transcriptomics to reveal the neutrophil dynamics in TME, (3) establish and utilize novel genetic perturbation tools to identify and functionally validate key regulators of neutrophil function in cancer. By analyzing the tissue/tumor-associated neutrophils from different microenvironment, we have identified distinct neutrophil subsets that are induced by different components of the TME. Therefore, our overall hypothesis is that specific factors in the tumor microenvironment such as the local microbiota and tissue-resident immune cells, as well as the genetic makeup and immunogenicity of cancer cells may differentially regulate the neutrophils. Our goal is to identify cell-extrinsic factors from the TME that reprogram neutrophils to functionally discrete subsets. Meanwhile, we will apply novel techniques to track TANs and dissect neutrophil-intrinsic pathways that direct their functional diversification in cancer. Our study will provide a blueprint for transcriptional control of neutrophil responses in cancer and opens possibilities for stage/gene/environment-specific therapeutic modulation of neutrophil function in cancer. Furthermore, the conceptual and technological advances generated here will build the foundation for future investigations into neutrophils in additional cancer types and beyond, shedding light on pathways and molecules that can serve as novel therapeutic targets to manipulate neutrophils for treating cancer and other diseases.

Project Narrative Chengcheng Jin, Ph.D Neutrophils have emerged as a critical player to promote cancer progression via diverse mechanisms; nevertheless, the regulatory mechanisms unique to tumor-associated neutrophils (TAN) are poorly understood. Taking an integrated approach that leverages genetically engineered mouse models with novel tools to track and manipulate TANs, we propose to (1) identify specific factors in the tumor microenvironment (TME) that reprogram neutrophils to functionally discrete subsets (2) dissect neutrophil-intrinsic pathways that direct their functional diversification in cancer. Our goal is to develop an in-depth and broad understanding of transcriptional and epigenetic reprogramming of neutrophils in the TME, elucidating targets for stage/gene/environment-specific therapeutic modulation of neutrophil function in cancer.