Elucidating Early Events in HGSC Pathogenesis: A Single-Cell Multiomics Approach to Robustly Trace Cell Lineage, Clonality, and Phenotypes of TP53-Mutated Cells
Abstract
The most common and lethal subtype of ovarian cancer is high-grade serous carcinoma (HGSC); the poor prognosis of HGSC in due in large part to the fact that most cases are unfortunately diagnosed at advanced stages of disease. An enigma in ovarian carcinoma pathogenesis is that the ovary contains no epithelial cell populations. The surface of the ovary has a specialized lining termed the ovarian surface epithelium (OSE) and, until recently, was thought to be the origin of HGSC. Over the past 15 years, it has been recognized that the fallopian tube may be the origin of most if not all so-called ovarian HGSC. This is largely based on the presence of intraepithelial (non-invasive) precursor lesions identified in the fallopian tube fimbria. Women with germline mutations in BRCA1/2 are known to be at high risk for developing HGSC. The traditional preventive strategy is early removal of the fallopian tubes and ovaries (prophylactic salpingo-oophorectomy), which induces surgical menopause. Alternative preventive efforts (removal of fallopian tubes with delayed oophorectomy) may avoid surgical menopause in young women at high risk for HGSC, allowing preservation of fertility as well as improving quality of life and cardiovascular health. However, these benefits must be weighed against the risk of developing ovarian cancer. Additionally, opportunistic salpingectomy, where the fallopian tubes are removed at the time of surgery for other indications (such as hysterectomy for fibroids), is an approach being employed in many institutions and may result in decreased incidence of ovarian carcinoma in women without known risk factors for HGSC. The effectiveness of these preventive approaches depends on the proportion of tumors that originate in the fallopian tube. This proposal addresses the critical problem of cell of origin in ovarian cancer. Precisely understanding the cell of origin for HGSC is at the core of delineating the risk of delayed oophorectomy and benefits of opportunistic salpingectomy. We will deploy an entirely novel approach to this critical problem using cutting-edge single-cell multi-omics technologies to enable understanding of the molecular changes that occur in HGSC and the earliest precursor lesions in the fallopian tube and to demonstrate, in the most direct way possible, cell of origin. To do this, we will leverage mitochondrial DNA mutation analysis at the single cell level. In addition to a cell s nucleus, mitochondria have their own genome. The mitochondrial genome accumulates mutations at a much higher rate (10- to 100-fold) than the nuclear genome owing to its lack of DNA repair machinery. Additionally, in contrast to the nuclear genome, which generally contains two copies of each gene, individual cells contain up to 1,000 mitochondria, with each mitochondrion containing 2-10 copies of the mitochondrial genome. In this way, mitochondrial mutations act like a natural barcode, or fingerprint, of a cell s history and origin. In each cell, we will analyze the mitochondrial mutations to allow for direct tracing of cell lineage from HGSC tumor cells to the benign epithelial cells of the fallopian tube, OSE, or endometrium. In addition, we will measure cellular protein abundances (including markers of fallopian tube epithelium and the TP53-encoded protein, a hallmark of HGSC) and chromatin accessibility states (epigenetic features independent of DNA sequence) to be able to track the change in cell differentiation and phenotypes over time. We plan to do this in tens of thousands of individual cells for each patient, creating an immense amount of data and a powerful way to directly track cell lineages. Specifically, we will trace the lineage of HGSC tumor cells all the way back to benign epithelium to determine the cell of origin. Our single cell multi-omics approach will also identify cellular features that may be targetable and/or uncover novel mechanisms of tumor progression. Addition
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 28, 2022
- Source ID
- W81XWH2210273
Entities
People
- Brooke Howitt
Organizations
- Stanford University
- United States Army