Although cytoreductive surgery followed by adjuvant chemotherapy is effective as a standard treatment for early-stage ovarian cancer, the majority of ovarian cancer cases are diagnosed at the advanced stages with dissemination to the peritoneal cavity, leading to a poor prognosis. Therefore, it is crucial to understand the cellular and molecular mechanisms underlying metastasis and identify novel therapeutic targets.
In this study, we aimed to elucidate the mechanisms underlying gene expression alterations during the acquisition of metastatic potential and characterize the metastatic subpopulations within ovarian cancer cells.
We conducted single-cell RNA sequencing of two human ovarian cancer cell lines: SKOV-3 and SKOV-3-13, a highly metastatic subclone of SKOV-3. Suppression of NFE2L1 expression was performed through siRNA-mediated knockdown and CRISPR-Cas9-mediated knockout.
Clustering and pseudotime trajectory analysis revealed pro-metastatic subpopulation within these cells. Furthermore, gene set enrichment analysis and prognosis analysis indicated that NFE2L1 could be a key transcription factor in the acquisition of metastasis potential. Inhibition of NFE2L1 significantly reduced migration and viability of both cells. In addition, NFE2L1 knockout cells exhibited significantly reduced tumor growth in a mouse xenograft model, recapitulating in silico and in vitro results.
The results presented in this study deepen our understanding of the molecular pathogenesis of ovarian cancer metastasis with the ultimate goal of developing treatments targeting pro-metastatic subclones prior to metastasis.

Wide peritoneal metastasis is the cause of the highest lethality of ovarian cancer in gynecologic malignancies. Ascites play a key role in ovarian cancer metastasis, but involved mechanism is uncertain. Here, we performed a quantitative proteomics of ascites, and found that collagen type I alpha 1 (COL1A1) was notably elevated in ascites from epithelial ovarian cancer patients compared to normal peritoneal fluids, and verified that elevated COL1A1 was mainly originated from fibroblasts. COL1A1 promoted migration and invasion of ovarian cancer cells, but such effects were partially eliminated by COL1A1 antibodies. Intraperitoneally injected COL1A1 accelerated intraperitoneal metastasis of ovarian cancer xenograft in NOD/SCID mice. Further, COL1A1 activated downstream AKT phosphorylation by binding to membrane surface receptor integrin β1 (ITGB1). Knockdown or blockage of ITGB1 reversed COL1A1 enhanced migration and invasion in ovarian cancer cells. Conversely, ovarian cancer ascites and fibrinogen promoted fibroblasts to secrete COL1A1. Elevated fibrinogen in ascites might be associated with increased vascular permeability induced by ovarian cancer. Our findings suggest that microenvironment remodeled by tumor cells and stromal cells promotes fibroblasts to secrete COL1A1 and facilitates the metastasis of ovarian cancer, which may provide a new approach for ovarian cancer therapeutics.

BACKGROUND: We aimed to develop inhibitory short peptides that can prevent protein interactions of SOS1/EPS8/ABI1 tri-complex, a key component essential for ovarian cancer metastasis.
METHODS: Plasmids containing various regions of HA-tagged ABI1 were co-transfected into ovarian cancer cells with Flag-tagged SOS1 or Myc-tagged EPS8. Co-immunoprecipitation and GST-pulldown assay were used to identify the regions of ABI1 responsible for SOS1 and EPS8 binding. Inhibitory short peptides of these binding regions were synthesized and modified with HIV-TAT sequence. The blocking effects of the peptides on ABI1-SOS1 or ABI1-EPS8 interactions in vitro and in vivo were determined by GST-pulldown assay. The capability of these short peptides in inhibiting invasion and metastasis of ovarian cancer cell was tested by Matrigel invasion assay and peritoneal metastatic colonization assay.
RESULTS: The formation of endogenous SOS1/EPS8/ABI1 tri-complex was detected in the event of LPA-induced ovarian cancer cell invasion. In the tri-complex, ABI1 acted as a scaffold protein holding together SOS1 and EPS8. The SH3 and poly-proline+PxxDY regions of ABI1 were responsible for SOS1 and EPS8 binding, respectively. Inhibitory short peptides p + p-8 (ppppppppvdyedee) and SH3-3 (ekvvaiydytkdkddelsfmegaii) could block ABI1-SOS1 and ABI1-EPS8 interaction in vitro. TAT-p + p-8 peptide could disrupt ABI1-EPS8 interaction and suppress the invasion and metastasis of ovarian cancer cells in vivo.
CONCLUSIONS: TAT-p + p-8 peptide could efficiently disrupt the ABI1-EPS8 interaction, tri-complex formation, and block the invasion and metastasis of ovarian cancer cells.

Ovarian cancer is an extremely lethal gynecologic disease; with the high-grade serous subtype predominantly associated with poor survival rates. Lack of early diagnostic biomarkers and prevalence of post-treatment recurrence, present substantial challenges in treating ovarian cancers. These cancers are also characterized by a high degree of heterogeneity and protracted metastasis, further complicating treatment. Within the ovarian tumor microenvironment, cancer stem-like cells and mechanical stimuli are two underappreciated key elements that play a crucial role in facilitating these outcomes. In this review article, we highlight their roles in modulating ovarian cancer metastasis. Specifically, we outline the clinical relevance of cancer stem-like cells, and challenges associated with their identification and characterization and summarize the ways in which they modulate ovarian cancer metastasis. Further, we review the mechanical cues in the ovarian tumor microenvironment, including, tension, shear, compression and matrix stiffness, that influence (cancer stem-like cells and) metastasis in ovarian cancers. Lastly, we outline the challenges associated with probing these important modulators of ovarian cancer metastasis and provide suggestions for incorporating these cues in basic biology and translational research focused on metastasis. We conclude that future studies on ovarian cancer metastasis will benefit from the careful consideration of mechanical stimuli and cancer stem cells, ultimately allowing for the development of more effective therapies.

Ovarian cancer is the fifth leading cause of cancer deaths in U.S. women and the deadliest gynecologic malignancy. This lethality is largely due to the fact that most cases are diagnosed at metastatic stages of the disease when the prognosis is poor. Epidemiologic studies consistently demonstrate that parous women have a reduced risk of developing ovarian cancer, with a greater number of births affording greater protection; however little is known about the impact of parity on ovarian cancer metastasis. Here we report that multiparous mice are less susceptible to ovarian cancer metastasis in an age-matched syngeneic murine allograft model. Interferon pathways were found to be upregulated in healthy adipose tissue of multiparous mice, suggesting a possible mechanism for the multiparous-related protective effect against metastasis. This protective effect was found to be lost with age. Based on this work, future studies exploring therapeutic strategies which harness the multiparity-associated protective effect demonstrated here are warranted.

Despite chemotherapy and surgical debulking options, ovarian cancer recurs and disseminates frequently, with poor prognosis. However, the molecular mechanisms underlying ovarian cancer metastasis still remain unelucidated. The tumor microenvironment, consisting of stromal cells (including fibroblasts, macrophages, regulatory T cells, myeloid-derived suppressor cells, endothelial cells, pericytes and platelets), the extracellular matrix component (EMC) (including inflammatory cytokines, chemokines, matrix metalloproteinases, integrins, and other secreted molecules) and exosomes (small extracellular vesicles loaded with molecules), establishes an autocrine-paracrine communication circuit that reinforces invasion and cancer cell metastasis via reciprocal signaling. Recent evidences have unraveled the significant contribution of tumor microenvironment to ovarian cancer metastasis. In this review, we provide a comprehensive landscape of the reciprocity between tumor stroma and ovarian cancer cells upon metastasis, aiming to offer novel clues on the development of novel diagnostic biomarkers and therapeutic targets for ovarian cancer in future clinical practice.

The current study presents a case of sarcoidosis manifesting as hepatic and splenic nodules, which was difficult to differentiate from ovarian cancer metastases. A 24-year-old female, who was previously diagnosed with right ovarian cancer and underwent surgery at the age of 21, was found to have two nodules in the spleen revealed by contrast-enhanced computed tomography (CT). 18F-fluorodeoxyglucose positron emission tomography/CT revealed two abnormal high uptake lesions in the spleen and one abnormal high uptake lesion in the liver. Under a diagnosis of hepatic and splenic metastases from right ovarian cancer, a laparoscopic splenectomy and partial hepatectomy were performed. Histopathological examination showed that a large number of non-caseating epithelioid cell granulomas formed these nodules, which was compatible with sarcoidosis. This case indicates that it is difficult to distinguish sarcoidosis from metastatic disease even using the latest modalities, and that laparoscopic surgery is a minimally invasive and useful tool for forming a differential diagnosis.

The role of mesothelial cells in the intraperitoneal spread of ovarian cancer is still elusive. In particular, it is unclear whether these cells constitute a passive barrier preventing cancer cell progression or perhaps act as an active promoter of this process. In this report we show that omental human peritoneal mesothelial cells (HPMCs) stimulate adhesion and proliferation of ovarian cancer cells (A2780, OVCAR-3, SKOV-3). The latter was associated with the paracrine activity of GRO-1, IL-6, and IL-8 released to the environment by HPMCs. Furthermore, the growth dynamics of ovarian cancer xenografts produced in response to i.p. injection of ovarian cancer cells together with HPMCs was remarkably greater than for implantation of cancer cells alone. A layer of peritoneal mesothelium was consistently present in close proximity to the tumor mass in every xenograft model. In conclusion, our results indicate that HPMCs play a supporting role in the intraperitoneal invasiveness of ovarian malignancy, whose effect may be attributed to their ability to stimulate adhesion and proliferation of cancer cells.

Although current treatments for localized ovarian cancer are highly effective, this cancer still remains the most lethal gynecological malignancy, largely owing to the fact that it is often detected only after tumor cells leave the primary tumor. Clinicians have long noted a clear predilection for ovarian cancer to metastasize to the soft omentum. Here, we show that this tropism is due not only to chemical signals but also mechanical cues. Metastatic ovarian cancer cells (OCCs) preferentially adhere to soft microenvironments and display an enhanced malignant phenotype, including increased migration, proliferation and chemoresistance. To understand the cell-matrix interactions that are used to sense the substrate rigidity, we utilized traction force microscopy (TFM) and found that, on soft substrates, human OCCs increased both the magnitude of traction forces as well as their degree of polarization. After culture on soft substrates, cells underwent morphological elongation characteristic of epithelial-to-mesenchymal transition (EMT), which was confirmed by molecular analysis. Consistent with the idea that mechanical cues are a key determinant in the spread of ovarian cancer, the observed mechanosensitivity was greatly decreased in less-metastatic OCCs. Finally, we demonstrate that this mechanical tropism is governed through a Rho-ROCK signaling pathway.

Background. Primary ovarian carcinoma with metastasis to the breast is rare, with only 39 cases reported in the current literature. Ovarian metastasis to the breast presenting as inflammatory breast carcinoma is even more infrequent, with only 6 cases reported.Case. We present a patient who developed metastatic inflammatory cancer of the breast from a stage IIIC papillary serous ovarian adenocarcinoma approximately 1 year after the original diagnosis. Pathologic analysis confirmed the origin of the tumor: a high-grade adenocarcinoma morphologically similar to the previously diagnosed ovarian cancer. In addition, the tumor was strongly positive on immunohistochemistry for CA-125, identical to the ovarian primary. The patient died of diffuse metastasis 5 months after the breast tumor was noted.Conclusion. Although ovarian metastasis to the breast presenting as inflammatory breast cancer is rare, it should be included in the differential diagnosis for any patient with a personal history of ovarian cancer. Accurate differentiation is necessary because treatment differs significantly for patients with ovarian metastasis to the breast, as compared with patients with primary inflammatory breast cancer. Ovarian metastasis to the breast confers a poor prognosis: patient survival ranged from 3 to 18 months, with a median survival of 6 months after the diagnosis of the breast metastasis.