NF-κB/Lipocalin 2 Signaling Pathway Mitigates the Chemoresistance of BRAFV600E-Mutant Colorectal Cancer to Cisplatin by Promoting Ferroptosis.

Background: Colorectal cancers (CRCs) harboring the BRAFV600E (V600E) mutation exhibit aggressive clinical behavior and chemotherapy resistance, yet the underlying mechanisms remain poorly understood. Ferroptosis, which is driven by iron-dependent lipid peroxidation, has emerged as a potential therapeutic vulnerability.

This study aimed to explore whether the NF-κB/Lipocalin 2 (LCN2) pathway modulates cisplatin sensitivity through Fenton-reaction-induced ferroptosis in BRAFV600E-overexpressing CRC cells. Methods: BRAF mutation status and the expression of LCN2, PTGS2, and cleaved caspase3 were examined in clinical CRC specimens by immunohistochemistry. The correlations between ferroptosis and apoptosis markers and 5-year survival rate were evaluated in TCGA datasets. CRC cells with LCN2 knockdown/knockout or BRAF/V600E/LCN2 overexpression were established to assess the proliferation, lipid metabolism, iron levels, and NF-κB/LCN2 signaling under cisplatin treatment.

In vivo studies were employed with BALB/c xenograft models. Results: V600E-mutant clinical specimens exhibit significantly reduced expression of the ferroptosis marker PTGS2, and the iron metabolism regulators LCN2. Within a KRAS-mutant cellular model, V600E overexpression attenuated cisplatin-induced ferroptosis through suppression of the NF-κB/LCN2 signaling axis, leading to impairment of Fenton-reaction-mediated lipid peroxidation. Restoration of LCN2 expression re-sensitized V600E-overexpressing cells to cisplatin both in vitro and in vivo.

Interestingly, inhibition of apoptosis contributes to the resistance of cisplatin induced ferroptosis in V600E overexpression cells, implying a crosstalk between ferroptosis and apoptosis within the therapeutic resistance. Conclusions: Our findings show that the NF-κB/LCN2 axis drives Fenton-reaction-induced ferroptosis to promote the vulnerability of V600E overexpression CRC cells within a KRAS-mutant background to cisplatin. LCN2 restoration partially overcomes V600E overexpression resistance both in vitro and in vivo, suggesting LCN2 as a promising therapeutic target. The crosstalk between ferroptosis and apoptosis may offer potential strategies to overcome chemotherapy resistance of this high-risk CRC subtype.