The discovery of cancer stem cells emphasized the importance of interactions between stem cells and their microenvironment. More than 2 decades of research in Drosophila have documented the capacity of the supporting cellular microenvironment or “niche” in orchestrating renewal and differentiation of stem cell populations. In the context of cancer, we expect proper organisation of the cellular microenvironment will also be essential for preventing tumour formation. However, this area of cancer biology has remained enigmatic due to the difficulty in tracing interactions between human tumours and their niche in mammals. This project will extend on our exciting observations that loss of the MYC repressor Hfp/FIR from the Drosophila ovarian stem cell niche generates germline tumours far from the local niche. We aim to extend these observations to human and mouse models to begin dissecting contributions of the tumour microenvironment to initiation and progression of ovarian cancer.