Single cell sequencing reveals heterogeneity within ovarian cancer epithelium and cancer associated stromal cells

Abstract

Objectives The purpose of this study was to determine the level of heterogeneity in high grade serous ovarian cancer (HGSOC) by analyzing RNA expression in single epithelial and cancer associated stromal cells. In addition, we explored the possibility of identifying subgroups based on pathway activation and pre-defined signatures from cancer stem cells and chemo-resistant cells. Methods A fresh, HGSOC tumor specimen derived from ovary was enzymatically digested and depleted of immune infiltrating cells. RNA sequencing was performed on 92 single cells and 66 of these single cell datasets passed quality control checks. Sequences were analyzed using multiple bioinformatics tools, including clustering, principle components analysis, and geneset enrichment analysis to identify subgroups and activated pathways. Immunohistochemistry for ovarian cancer, stem cell and stromal markers was performed on adjacent tumor sections. Results Analysis of the gene expression patterns identified two major subsets of cells characterized by epithelial and stromal gene expression patterns. The epithelial group was characterized by proliferative genes including genes associated with oxidative phosphorylation and MYC activity, while the stromal group was characterized by increased expression of extracellular matrix (ECM) genes and genes associated with epithelial-to-mesenchymal transition (EMT). Neither group expressed a signature correlating with published chemo-resistant gene signatures, but many cells, predominantly in the stromal subgroup, expressed markers associated with cancer stem cells. Conclusions Single cell sequencing provides a means of identifying subpopulations of cancer cells within a single patient. Single cell sequence analysis may prove to be critical for understanding the etiology, progression and drug resistance in ovarian cancer.

Decoding transcriptomic intra‐tumour heterogeneity to guide personalised medicine in ovarian cancer

“…A recent study utilised the single‐cell RNA sequencing approach to profile one single HGSOC tumour sample and identified two distinct cell populations. Both an epithelial cell population and a separate mesenchymal, stem cell‐like population were identified, reaffirming the prevalence of ITH in OC .…”

Ovarian cancer‐associated mesothelial cells induce acquired platinum‐resistance in peritoneal metastasis via the FN1/Akt signaling pathway

“…CAFs, potentially originating from various types of cells, appear in all stages of cancer and have pivotal roles in creating tumor microenvironments . As it relates to OvCa, a variety of CAFs have been reported to comprise the tumor stroma, thereby contributing to the development of stromal heterogeneity . Moreover, it has been recognized that mesenchymal conversion of MCs is associated with tissue fibrosis in peritoneal dialysis .…”

“…25 As it relates to OvCa, a variety of CAFs have been reported to comprise the tumor stroma, thereby contributing to the development of stromal heterogeneity. 43,44 Moreover, it has been recognized that mesenchymal conversion of MCs is associated with tissue fibrosis in peritoneal dialysis. 45,46 It has also been proposed that the transition of mesothelial cells, predominantly initiated by TGF-β1, has an important role in the development of peritoneal metastasis.…”

Challenges and Opportunities in Studying the Epidemiology of Ovarian Cancer Subtypes

“…New experimental techniques provide the opportunity to interrogate such hypotheses directly. This phenomenon has been observed in 66 single cells in a HGSC tumor [87] and a subset of glioblastoma tumors by single cell profiling [88]. However, it has been recently shown that glioblastoma tumors are inherently heterogeneous by chance [89], and more single cell data is required to fully explore this phenomenon.…”