Specific Mechanisms of Chromosomal Instability Indicate Therapeutic Sensitivities in High-Grade Serous Ovarian Carcinoma

Abstract

Chromosomal instability (CIN) comprises continual gain and loss of chromosomes or parts of chromosomes and occurs in the majority of cancers, often conferring poor prognosis. Due to a scarcity of functional studies and poor understanding of how genetic or gene expression landscapes connect to specific CIN mechanisms, causes of CIN in most cancer types remain unknown. High-grade serous ovarian carcinoma (HGSC), the most common subtype of ovarian cancer, is the major cause of death due to gynaecological malignancy in the Western world, with chemotherapy resistance developing in almost all patients. HGSC exhibits high rates of chromosomal aberrations and knowledge of causative mechanisms would represent an important step towards combating this disease. Here we perform the first in-depth functional characterization of mechanisms driving CIN in HGSC in seven cell lines that accurately recapitulate HGSC genetics. Multiple mechanisms co-existed to drive CIN in HGSC, including elevated microtubule dynamics and DNA replication stress that can be partially rescued to reduce CIN by low doses of paclitaxel and nucleoside supplementation, respectively. Distinct CIN mechanisms indicated relationships with HGSC-relevant therapy including Poly (ADP-Ribose) Polymerase (PARP) inhibition and microtubule-targeting agents. Comprehensive genomic and transcriptomic profiling revealed deregulation of various genes involved in genome stability but were not directly predictive of specific CIN mechanisms, underscoring the importance of functional characterization to identify causes of CIN. Overall, we show that HGSC CIN is complex and suggest that specific CIN mechanisms could be used as functional biomarkers to indicate appropriate therapy. Statement of SignificanceFindings characterize multiple deregulated mechanisms of genome stability that lead to chromosomal instability in ovarian cancer and demonstrate the benefit of integrating analysis of said mechanisms into predictions of therapy response.

Modelling TGFβR and Hh pathway regulation of prognostic matrisome molecules in ovarian cancer

“…AOCS1 was also established from a patient with HGSOC and kept at a low passage number. Both cell lines showed genetic changes characteristic of HGSOC (Tamura et al, 2020). The original tissue biopsies for both cell lines showed malignant cell PAX8 positivity and cell lines cultured in vitro maintained PAX8 nuclear positivity (Figure 3A).…”

“…The G164 cell line was established in our laboratory from an omental HGSOC tumor collected during interval debulking surgery in 2015. G164 cells were TP53 and PAX8 positive (Tamura et al, 2020). Malignant cells were cultured in DMEM:F12 (Gibco), 10% FCS, 1% penicillin and streptomycin in a 5% CO2 humidified incubator at 37 C. The immortalized human FTSE cell line, wild-type FT318, was kindly given by Professor Ronny Drapkin (Perelman School of Medicine, University of Pennsylvania) and grown in serum-free WIT-P medium (Cellaria) without antibiotics and 100ng/ml cholera toxin (Sigma-Aldrich).…”

Effects of long-term norepinephrine treatment on normal immortalized ovarian and fallopian tube cells

“…HGSOC is characterized by highly abnormal karyotypes along with other features of genomic instability including numerical and structural variants 32 – 35 . CIN has also be demonstrated in ovarian cancer cell lines and in ascites derived from patients with HGSOC and several underlying mechanisms have been suggested, including DNA replication stress and elevated microtubule dynamics 33 , 36 .…”

A human multi-cellular model shows how platelets drive production of diseased extracellular matrix and tissue invasion

“…The medium was then replaced with 200 ml of mesothelial cell medium (Medium 199 (Gibco) with insulin-transferrin-selenium (Gibco), 10% heat-inactivated FBS (Hyclone) and penicillin-streptomycin (Sigma-Aldric)) containing 200,000 human primary mesothelial cells and incubated for 24 hr. G164 or AOCS1 ovarian cancer cells (Tamura et al, 2020) were then seeded at 40,000 cells per gel and incubated for 24 hr before loosening and transferring the gels to a 24 well dish in growth medium. To make up the penta-culture model, a ratio of 1:100 cancer cells:isolated platelets was added to the culture.…”

“…(H) Hierarchical cluster analysis of tetra-and penta-culture illustrates that both cluster more closely with historic HGSOC RNASeq (Pearce et al, 2018) Next we asked if we could use this cell model to study malignant cell invasion. We added HGSOC cell lines AOCS1 (Milagre et al, 2015) (Figure 1F) or G164 (Tamura et al, 2020) (Figure 1G) as a single cell suspension, creating an omental metastasis tetra-culture model. We found that both AOCS1 and G164 malignant cells attached to the surface of the cultures forming colonies (Figure 1G), similar to what we observed in patient tissues of early metastatic lesions (Figure S1A), where they could be clearly defined from other cells present in the model using nuclear PAX8 as a marker.…”