Tang-Yuan Chu

Ovulation-Derived Fibronectin Promotes Peritoneal Seeding of High-Grade Serous Carcinoma Precursor Cells via Integrin β1 Signaling

High-grade serous ovarian carcinoma (HGSC) is predominantly diagnosed at advanced stages with extensive peritoneal metastasis. A pivotal early event in HGSC development is the peritoneal seeding of tumor cells originating from the fallopian tube epithelial (FTE) precursor lesions. Ovulation releases follicular fluid (FF), which is known to contain oncogenic factors that promote FTE cell transformation. However, the specific mechanisms and factors within FF that drive the early metastatic seeding of precancerous FTE cells remain poorly defined. We investigated the role of FF in the peritoneal dissemination of FTE-derived cells, and the abundance of fibronectin (FN) as a potential key mediator. Functional assays were performed using FN-depleted FF to assess its impact on migration, invasion, anchorage-independent growth, and peritoneal attachment. The role of the fibronectin receptor, integrin β1 (ITGB1), and the signaling pathways were evaluated via knockdown studies. In vivo xenograft models were used to quantify peritoneal seeding, and mechanistic studies elucidated the involved signaling pathways. We identified FN as a critical component of FF, present at high concentrations (~210 µg/mL), that potently drives FTE cell migration, invasion, and peritoneal seeding. Depletion of FN from FF abrogated the majority of these pro-metastatic activities in vitro and led to a dramatic 82% reduction in peritoneal tumor seeding in vivo. Knockdown of ITGB1 similarly impaired seeding. Mechanistically, FF-derived FN activates the ITGB1/FAK-SRC signaling pathway to promote tumor cell motility and colonization. Our study establishes FF-fibronectin as an important regulator of the early peritoneal seeding of HGSC precursor cells. These findings reveal a direct link between ovulation and HGSC development, suggesting that targeting the FN-ITGB1 signaling axis may offer a novel preventive strategy for high-risk individuals.

A Novel Serum-Based Bioassay for Quantification of Cancer-Associated Transformation Activity: A Case–Control and Animal Study

Background/Objectives: The detection of ovarian cancer remains challenging due to the lack of reliable serum biomarkers that reflect malignant transformation rather than mere tumor presence. We developed a novel biotest using an immortalized human fallopian tube epithelial cell line (TY), which exhibits anchorage-independent growth (AIG) in response to cancer-associated serum factors. Methods: Sera from ovarian and breast cancer patients, non-cancer controls, and ID8 ovarian cancer-bearing mice were tested for AIG-promoting activity in TY cells. Results: TY cells (passage 96) effectively distinguished cancer sera from controls (68.50 ± 2.12 vs. 17.50 ± 3.54 colonies, p < 0.01) and correlated with serum CA125 levels (r = 0.73, p = 0.03) in ovarian cancer patients. Receiver operating characteristic (ROC) analysis showed high diagnostic accuracy (AUC = 0.85, cutoff: 23.75 colonies). The AIG-promoting activity was mediated by HGF/c-MET and IGF/IGF-1R signaling, as inhibition of these pathways reduced phosphorylation and AIG. In an ID8 mouse ovarian cancer model, TY-AIG colonies strongly correlated with tumor burden (r = 0.95, p < 0.01). Conclusions: Our findings demonstrate that the TY cell-based AIG assay is a sensitive and specific biotest for detecting ovarian cancer and potentially other malignancies, leveraging the fundamental hallmark of malignant transformation.

Ovulation releases G-CSF to induce peritoneal neutrophil influx and netosis, facilitating peritoneal seeding of high-grade serous carcinoma

High-grade serous ovarian cancer (HGSC), the most lethal subtype of epithelial ovarian cancer (EOC), often originates from serous tubal intraepithelial carcinoma (STIC) and is typically diagnosed at advanced stages. However, the mechanisms underlying the dissemination of STIC cells into the peritoneal cavity remain poorly understood. This study aims to clarify whether the immune microenvironment triggered by physiological ovulation contributes to this early metastatic process. We investigated the link between ovulation-induced peritoneal neutrophil extracellular trap (NET) formation, NETosis, and cancer cell seeding. Peritoneal fluid from humans and mice at various ovulatory stages was analyzed for immune cell composition. NETosis was assessed by neutrophil DNA staining and detection of PAD4 and citrullinated histone H3 (CitH3). STIC-mimicking and HGSC cells were used with or without NET inhibition to evaluate effects on early metastatic seeding. Ovulatory follicular fluid (FF) robustly induced peritoneal neutrophil recruitment and rapid NET formation via a G-CSF-mediated, ROS/NOX/PAD4-dependent mechanism. NETs promoted cell clustering and anchorage-independent growth through extracellular DNA, while NET-derived soluble factors enhanced cell adhesion and invasion. In vivo, exposure to FF enhanced early intraperitoneal tumor cell seeding, which was significantly reduced by PAD4 inhibition. Physiological ovulation induces neutrophil influx and NETosis, creating a pro-metastatic peritoneal niche that facilitates both the dissemination and transformation of STIC cells. These findings reveal a novel mechanism linking ovulation to HGSC progression and suggest NETosis as a potential target for early intervention.