Sodium-glucose cotransporter 1 exacerbates colon cancer malignancy by suppressing ferroptosis via the Nrf2/HO-1/SLC7A11/GPX4 axis under high glucose conditions.

BACKGROUND

Hyperglycemia is an independent risk factor for colon cancer progression, but its underlying mechanisms remain unclear. Ferroptosis is a form of programmed cell death, yet whether sodium-glucose cotransporter 1 (SGLT1) regulates ferroptosis to affect colon cancer under high glucose has not been reported. This study aims to clarify the mechanism by which SGLT1 regulates the malignant phenotype of colon cancer under high-glucose conditions and explore the therapeutic potential of targeting SGLT1 combined with ferroptosis inducers.

METHODS

HT29 and SW480 cells were treated with mmol/L high glucose. Cell proliferation and migration were detected by CCK-8, colony formation and wound-healing assays. Ribonucleic acid sequencing (RNA-seq) screened SGLT1-regulated downstream pathways. Ferroptosis was evaluated by malondialdehyde (MDA), glutathione (GSH), reactive oxygen species (ROS), ferrous ions (Fe2+) levels and mitochondrial ultrastructure. Western blot detected nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1)/solute carrier family 7 member 11 (SLC7A11)/glutathione peroxidase 4 (GPX4) pathway proteins. Interventions included ferrostatin-1 (Fer-1), tert-butylhydroquinone (TBHQ) and SLC7A11 overexpression. In vivo antitumor efficacy was assessed in diabetic nude mouse xenografts.

RESULTS

High glucose significantly enhanced HT29 and SW480 cell viability, colony formation and migration, with upregulated SGLT1. SGLT1 knockdown reversed these phenotypes, while overexpression aggravated them. RNA-seq showed ferroptosis was the most enriched pathway after SGLT1 knockdown, with downregulated GPX4 and SLC7A11. Only Fer-1 reversed SGLT1 knockdown-induced cell viability decrease (78.5%, P < 0.0001). SGLT1 knockdown increased MDA (3.53/3.40 vs. 2.33 nmol/mL, P < 0.0001), ROS (6.91/7.12 vs. 3.57 a.u., P < 0.01) and Fe2+ (44.50/44.74 vs. 8.54 a.u., P < 0.0001), decreased GSH (35.93/37.04 vs. 46.96 μg/mL, P < 0.0001), and induced mitochondrial atrophy; overexpression had opposite effects. SLC7A11 overexpression restored GPX4 (0.97 vs. 0.40, P = 0.0187) and reversed ferroptosis and growth inhibition. SGLT1 knockdown suppressed Nrf2/HO-1, which was rescued by TBHQ, increasing HO-1 (1.03 vs. 0.62, P = 0.0218), SLC7A11 (0.99 vs. 0.56, P = 0.0303) and GPX4 (1.37 vs. 0.30, P = 0.0065), while concurrently reversing ferroptosis. In vivo, SGLT1 knockdown reduced tumor weight from 264.6 to 36.76 mg (P < 0.0001); mizagliflozin plus erastin achieved 90.69% tumor inhibition (Bliss score 0.087).

CONCLUSIONS

High glucose promotes colon cancer cell proliferation and migration by upregulating SGLT1. SGLT1 is a key driver of high glucose-induced colon cancer malignant phenotypes. SGLT1 knockdown inhibits colon cancer mainly by activating ferroptosis, characterized by increased lipid peroxidation, GSH depletion, iron accumulation and mitochondrial atrophy. SGLT1 regulates ferroptosis via the SLC7A11/GPX4 axis. It inhibits ferroptosis by activating Nrf2/HO-1 to upregulate SLC7A11 and GPX4. Targeting SGLT1 enhances colon cancer cell sensitivity to ferroptosis inducers. Combined targeting of SGLT1 and ferroptosis is a novel therapeutic strategy for diabetic colon cancer patients.