Tumour-infiltrating Tregs (TI-Tregs) and stromal cells, including epithelial stem cells (SCs), are key components of the tumour-microenvironment and play important roles in cancer progression, yet their relationships and interdependencies remain poorly understood. To elucidate TI-Treg association with diverse tumour-supporting accessory cell types, this project will explore immediate early changes in their single-cell transcriptomes and intratumoural localisation in i) mouse cancer models (e.g. B16-F10 melanoma) where Tregs are genetically deleted, and ii) primary human tumour sample analysis.
Year 1/2. Identifying Treg SC niches. a) Identify the abundance and activation of Tregs and accessory cell types in tumour tissues by flow cytometry and imaging using reporter mice for Foxp3 (transcription factor to identify Tregs) b) Conditional deletion of Tregs in Foxp3-DTR mice during early tumour development to assess impact on tumour cell populations using RNA sequencing and multi-labelled tissue array (TAs) based in situ transcriptomic and proteomics.
Year 2/3. Interrogate Treg function via manipulation of the niche. We hypothesise that deletion of Tregs during early cancer development will impact specific populations of stromal and/or epithelial SCs. We will then assess the impact on tumour-progression and metastasis in the cancer model.
Year 3/4. Characterizing tumour SC-Treg dialogue. Single-cell RNA sequencing will be used to unravel the molecular basis of the tumour SC-Treg dialogue in tumours, through identification of pairs of ligands/receptors that are expressed by tumour cells and Tregs. The candidate molecules in the niche will be tested using using Cre/lox mediated conditional gene-targeting and validation in human tumour samples using TAs and flow cytometry.
The Ali lab has specific expertise in tissue immune cell-stem cell interactions and has established genetic tools to study Tregs and tissue stromal cells in cancer models. The Lombardi lab has over 30 years of experience with studying the mechanisms used by both human and mouse TI-Tregs.