Stefania Scicchitano

Ferroptosis Induction is Insufficient to Ensure NK Cell Activation in High-Grade Ovarian Cancer

Background: High-grade ovarian cancer (HGOC) is a heterogeneous and aggressive malignancy with a tumor microenvironment (TME) that suppresses immune responses, limiting immunotherapy efficacy. Ferroptosis, an iron-dependent form of regulated cell death, has emerged as a potential therapeutic target. Methods: We investigated the immunomodulatory effects of the ferroptosis inducer RAS-Selective Lethal 3 (RSL3) in four HGOC cell lines (ES-2, OVCAR-5, HEY, PEO-1) using flow cytometry and lactate dehydrogenase (LDH) release assays. Results: RSL3 modulated Natural Killer (NK) ligand expression in a cell line-dependent manner, resulting in differential susceptibility to NK cell-mediated cytotoxicity. OVCAR-5 cells became more susceptible to NK cell killing after treatment, whereas HEY cells showed reduced susceptibility, and ES-2 and PEO-1 cells exhibited minimal changes. Conclusions: Ferroptosis induction alone does not consistently enhance NK cell-mediated cytotoxicity in HGOC cells. These findings underscore the heterogeneity of tumor responses and highlight the need for further studies, particularly in in vivo models, to elucidate mechanisms linking ferroptosis to immune recognition and thereby inform therapeutic development.

Zinc Finger 521 Modulates the Nrf2-Notch Signaling Pathway in Human Ovarian Carcinoma

The human zinc finger protein 521 (ZNF521) is a co-transcriptional factor with multiple recognized regulatory functions in a range of normal, cancer and stem cell compartments. ZNF521 regulates proliferation, progression and CSC (cancer stem cell) compartments in human ovarian cancer (hOC), which is a very aggressive and late-diagnosed female tumor. Two other important regulators of hOC are the NRF2 and NOTCH signaling pathways. In the present paper, the mRNA and protein levels of ZNF521 were correlated with those of the NRF2-NOTCH signaling components in two different hOC cell lines and in a public dataset of 381 hOC patients. The data show that high levels of ZNF521 significantly increase NRF2-NOTCH signaling expression; conversely, the silencing of ZNF521 impairs NRF2-NOTCH signaling. This experimental work shows that, in hOC, different levels of ZNF521 modulate the NRF2-NOTCH signaling pathway and also influences hOC CSC properties.

The Double-Edged Sword of Oleuropein in Ovarian Cancer Cells: From Antioxidant Functions to Cytotoxic Effects

Oleuropein plays a key role as a pro-oxidant as well as an antioxidant in cancer. In this study, the activity of oleuropein, in an in vitro model of ovarian (OCCs) and breast cancer cells (BCCs) was investigated. Cell viability and cell death were analyzed. Oxidative stress was measured by CM-H2DCFDA flow cytometry assay. Mitochondrial dysfunction was evaluated based on mitochondrial reactive oxygen species (ROS) and GPX4 protein levels. Further, the effects on iron metabolism were analyzed by measuring the intracellular labile iron pool (LIP). We confirmed that high doses of oleuropein show anti-proliferative and pro-apoptotic activity on HEY and MCF-7 cells. Moreover, our results indicate that low doses of oleuropein impair cell viability without affecting the mortality of cells, and also decrease the LIP and ROS levels, keeping them unchanged in MCF-7 cells. For the first time, our data show that low doses of oleuropein reduce erastin-mediated cell death. Interestingly, oleuropein decreases the levels of intracellular ROS and LIP in OCCs treated with erastin. Noteworthily, we observed an increased amount of ROS scavenging enzyme GPX4 together with a consistent reduction in mitochondrial ROS, confirming a reduction in oxidative stress in this model.

Enhanced ZNF521 expression induces an aggressive phenotype in human ovarian carcinoma cell lines

Epithelial ovarian carcinoma (EOC) is the most lethal gynecological tumor, that almost inevitably relapses and develops chemo-resistance. A better understanding of molecular events underlying the biological behavior of this tumor, as well as identification of new biomarkers and therapeutic targets are the prerequisite to improve its clinical management. ZNF521 gene amplifications are present in >6% of OCs and its overexpression is associated with poor prognosis, suggesting that it may play an important role in OC. Increased ZNF521 expression resulted in an enhancement of OC HeyA8 and ES-2 cell growth and motility. Analysis of RNA isolated from transduced cells by RNA-Seq and qRT-PCR revealed that several genes involved in growth, proliferation, migration and tumor invasiveness are differentially expressed following increased ZNF521 expression. The data illustrate a novel biological role of ZNF521 in OC that, thanks to the early and easy detection by RNA-Seq, can be used as biomarker for identification and treatment of OC patients.