# SREBP1 knockdown triggers ferroptosis by suppressing the Nrf2-XCT/GPX4 axis in ovarian cancer

## TL;DR

This study shows that reducing SREBP1 in ovarian cancer cells causes cell death through ferroptosis by weakening the Nrf2-XCT/GPX4 pathway.

## Contribution

The study reveals a novel mechanism linking SREBP1 to ferroptosis resistance via the Nrf2-XCT/GPX4 axis in ovarian cancer.

## Key findings

- SREBP1 silencing reduces GSH, XCT, and GPX4 levels while increasing lipid peroxidation, inducing ferroptosis.
- SREBP1 silencing suppresses proliferation and EMT in ovarian cancer cells.
- Nrf2 activator THBQ reverses SREBP1 silencing effects, confirming the role of Nrf2 in the process.

## Abstract

Reprogramming of lipid metabolism is a hallmark of malignant tumors, and targeting key enzymes in lipid metabolism has emerged as a critical strategy to inhibit tumor progression. Sterol regulatory element-binding protein 1 (SREBP1), a master regulator of lipid biosynthesis, drives lipid metabolic reprogramming that not only promotes malignant progression but also confers resistance to ferroptosis in tumor cells. Ferroptosis is a distinct form of regulated cell death characterized by iron accumulation and lipid peroxidation. In this study, we demonstrate that silencing SREBP1 in ovarian cancer cells leads to decreased glutathione (GSH) levels, reduced protein expression of XCT and GPX4, and increased levels of malondialdehyde (MDA) and lipid peroxidation, indicating that SREBP1 silencing induces ferroptosis in ovarian cancer cells. Further experiments, including the CCK-8, EdU, colony formation assays and flow cytometry, confirmed that SREBP1 silencing suppresses proliferation by inducing cell cycle arrest. Transwell assays, immunofluorescence (IF) staining, Nile Rad staining, and measurements of triglyceride (TG) and total cholesterol (TC) levels demonstrated that SREBP1 silencing inhibits epithelial–mesenchymal transition (EMT) and lipid synthesis in ovarian cancer cells. Notably, SREBP1 silencing downregulates the expression of Nrf2, and treatment with the Nrf2 activator THBQ reverses the effects of SREBP1 silencing on ovarian cancer cell proliferation and ferroptosis. Mechanistically, SREBP1 silencing promotes ubiquitination-mediated degradation of the Nrf2 protein, thereby suppressing the expression of XCT and GPX4, ultimately triggering ferroptosis in ovarian cancer cells. Our findings establish SREBP1 as a key mediator of ferroptosis resistance and nominates it as both a therapeutic target and a potential prognostic biomarker in ovarian cancer.

Schematic diagram illustrating the mechanism whereby silent SREBP1 mediates the Nrf2/XCT/GPX4 pathway to induce ferroptosis in ovarian cancer cells.

Schematic diagram illustrating the mechanism whereby silent SREBP1 mediates the Nrf2/XCT/GPX4 pathway to induce ferroptosis in ovarian cancer cells.