SEMINAR: María Martín / Irene Zúñiga Centenero

12:00 – 12:30: María Martín Grau

Effect of PFOA exposure on a chronic mouse model of MASLD

Abstract:

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) encompasses a spectrum of liver conditions, beginning with fat accumulation in hepatocytes (steatosis) and potentially progressing to inflammation and fibrosis. Various factors contribute to MASLD, including exposure to endocrine-disrupting chemicals (EDCs). EDCs are exogenous compounds that mimic endogenous molecules (e.g., hormones), disrupting cellular metabolism by activating or inhibiting different receptors. The liver, as a key organ for xenobiotic metabolism, is particularly vulnerable to these chemicals. Per fluorinated compounds like perfluorooctanoic acid (PFOA), widely used for their grease-repelling properties, have been associated with obesity and fatty liver. Emerging evidence suggests that PFOA exposure may initiate or exacerbate MASLD. This study aims to elucidate the molecular mechanisms through which PFOA affects MASLD development and progression.

Methods: A 38-week chronic study was conducted using C57BL/6NTac mice. Male and female animals were assigned to different experimental groups, fed either a chow or GAN diet, and exposed to either no PFOA, 0.05 mg/day/kg PFOA in drinking water, or 0.3 mg/day/kg PFOA in drinking water. Food and water intake, as well as body weight, were monitored weekly. Urine, serum, and fecal samples were collected longitudinally at seven different time points. At euthanasia, all organs were collected, along with a final serum sample. Urine, serum, feces, and liver samples were analyzed by liquid chromatography–mass spectrometry (LC-MS). RNA was extracted from liver samples for sequencing. In addition, liver tissue was analyzed by histology.

Results: Sample analysis is currently ongoing; therefore, the results presented are preliminary. GAN-fed and PFOA-treated groups exhibited increased liver weight, which was significant in both males and females. Histological analysis did not reveal overt steatosis but suggested mild inflammatory changes. RNA-seq analysis showed significant differences between control and PFOA-treated groups, as well as between chow- and GAN-fed animals.
Conclusion: Long-term exposure to PFOA alters liver metabolism and increases liver weight. These findings support further studies to better define the molecular mechanisms by which PFOA influences MASLD progression.

12:30 – 13:00: Irene Zúñiga Centenero

Hyaluronan Promotes Cancer Plasticity in High Grade Serous Ovarian Cancer

Abstract:

High­grade serous ovarian cancer (HGSOC) is the deadliest epithelial ovarian cancer, usually diagnosed at advanced stages with peritoneal metastases and malignant ascites. In the HGSOC microenvironment, hyaluronic acid (HA) drives extracellular matrix remodelling and metastasis. In this context, HAS2 is the isoform responsible for the production of high-molecular-weight hyaluronic acid (HMW-HA), which is associated with tumour progression. Altered HA promotes an immunosuppressive niche facilitating peritoneal dissemination Consequently, this study focuses on the role of HMW-HA in the plasticity and progression of HGSOC.

Clinical analysis of HAS2 using KMplot showed that its overexpression is associated with an increased risk of relapse (HR=2.32). To investigate this finding further, HAS2 was overexpressed in a murine HGSOC cell line (HGS2). Spheroid formation under 3D conditions, the response to HA inhibitors (hyaluronidase and 4-MU), transcriptomic profiles (RNA-seq), cellular metabolism and mechanical properties were evaluated. Furthermore, in vivo studies of ascites formation were conducted.

Overexpression of HAS2 promoted the formation of microsatellites and increased survival under non-adherent conditions, effects that were reversed by HA inhibition. Transcriptomic analysis revealed an enrichment in hypoxia-related pathways. Functionally, the cells exhibited increased ATP-coupled respiration and lipid accumulation. Furthermore, the spheroids exhibited greater deformability and lower compaction, whilst in vivo they induced earlier ascites formation. Additionally, a drug screen was conducted, identifying compounds capable of inhibiting microsatellite formation. Taken together, HMW-HA was found to drive tumour aggressiveness through metabolic adaptation, making it a potential therapeutic target.

To investigate the contribution of HMW­HA to HGSOC plasticity, HAS2 was overexpressed in a murine HGSOC cell line (HGS2). HAS2 overexpression promoted microsatellite formation around spheroids and enhanced survival under 3D non­adherent conditions, mimicking malignant ascites. Treatment with recombinant hyaluronidase or 4­methylumbelliferone (4­MU) prevented microsatellite formation without disrupting spheroid cores, indicating a specific role for HMW­HA in tumour cell plasticity. RNA­seq analysis of HAS2­overexpressing cells revealed enrichment of hypoxia­related gene ontology terms. Functionally, these cells exhibited increased ATP­linked respiration and neutral lipid accumulation. Mechanical compression assays further demonstrated greater deformability and reduced compactness in HGS2­HAS2 spheroids, consistent with enhanced mechanical compliance.

In vivo, HAS2­expressing cells induced earlier ascites formation. Based on these findings, we are currently performing a drug repurposing screen using the Prestwick Chemical Library to identify compounds capable of targeting HA­driven plasticity.

Collectively, these results identify HMW­HA as a driver of metabolic adaptation and aggressiveness in HGSOC, highlighting HA metabolism as a promising therapeutic vulnerability.