High-grade serous ovarian cancer is the most deadly type of the disease, and is the 5th leading cause of cancer mortality in women in the United States. Ovarian cancer is actually a misnomer, as it is increasingly clear that at least 50%-60% of HGSOC cases are derived from the fallopian tube (FT), not the ovary. In vitro pre-clinical models that recapitulate the diversity of HGSOC are urgently needed to better understand disease pathogenesis and therapeutic response. However, ovarian cancer is highly underrepresented in public repositories with only handful of cell lines available. A paucity of suitable cell culture-based systems, especially FT-derived lines, that properly model disease and can be used to evaluate targeted therapies remains a key bottleneck for improving ovarian cancer outcomes.
“Organoids” are in vitro 3D-structures, derived from tissue stem cells that provide miniaturized, simplified versions of an organ. Organoids have been found to be powerful tools for exploring the effectiveness of current and experimental cancer therapies in many systems, including colon, lung, prostate and brain tumors. I have developed a 3D organoid culture system from normal mouse FT and the mouse equivalent of serous tubular intraepithelial carcinomas (STICs), a pre-malignant lesion. In my system, organoids derived from single cells indefinitely self-renew and form tube-like structures containing ciliated and secretory cells. I have also found that tumor organoids from a mouse model of HGSOC can faithfully recapitulate STIC parameters in vitro and form tumors following transplantation in mice.
My system enables the use of powerful mouse genetic systems and potentially rapid transit between in vitro and in vivo models of HGSOC pathogenesis. However, two major problems remain to credential organoids as valid models of normal FT development and HGSOC: 1) the origin of the putative stem cell for normal FT organoids is not clear; and 2) although large-scale genomic sequencing projects have generated a catalog of genetic lesions associated with HGSOC, it is unclear whether the pathologic effects of these mutations can be modeled using organoids.
Hence, the over-arching goals of my proposal are: (1) To use a technique called “lineage-tracing” combined with mouse models to test the ability of specific cell types within the FT to give rise to organoids. By combining lineage tracing with an exciting new technology that allows single cells to be sequenced, I will attempt to identify adult FT stem cells, the cells that give rise to all other cell types in the FT. (2) To use state-of-the art genetic manipulation strategies to introduce select combinations of human HGSOC mutations into organoids, measure effects on organoid properties in vitro, and generate genetically defined HGSOC in vivo. Successful completion of these aims should provide new insights into the origin and pathogenesis of HGSOC and could enable new therapeutic approaches for this deadly disease.