During the microbial degradation of borneol, a bicyclic plant monoterpene, it is first converted into camphor by borneol dehydrogenase (BDH) and then enters a known camphor-degradation pathway. Previously, a recombinant Pseudomonas BDH was found in inclusion bodies when expressed in Escherichia coli. After refolding, it was still unstable and was difficult to concentrate. Here, the protein-expression conditions were improved by changing the medium from lysogeny broth to Terrific Broth, yielding a soluble form of the enzyme with higher activity. The protein was crystallized and its 3D structure was determined by X-ray diffraction. Like other known homologues such as quinuclidinone reductase, the protein forms a tetramer with subunits containing Rossmann folds. Structural comparison revealed major differences in the C-terminal helices and the associated loops. It is likely that these regions contain the determinants for substrate recognition.

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.

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.