Paclitaxel Induces Neurotoxicity via Activating Ferroptosis by Suppressing Nrf2/SLC7A11/GSH/GPX4 Signaling

Abstract

Chemotherapy-induced neurotoxicity (CIN) is a prevalent and debilitating side effect of cancer treatment, with paclitaxel being a classic anticancer drug that often causes significant neurotoxicity. However, effective interventions are lacking. This study aimed to elucidate the mechanisms underlying paclitaxel-induced neurotoxicity. We confirmed that paclitaxel exerts cytotoxic effects on SH-SY5Y and HT-22 neuronal cells. RNA-seq analysis revealed that ferroptosis is among the top enriched pathways in paclitaxel-treated neurons, and gene set enrichment analysis (GSEA) confirmed the enrichment of ferroptosis-related pathways. Transmission electron microscopy showed fragmented mitochondria with decreased cristae and increased membrane density, characteristic of ferroptosis. Paclitaxel dose-dependently increased intracellular reactive oxygen species (ROS) and iron levels while decreasing glutathione (GSH) levels. Mechanistically, paclitaxel suppressed the expression of Nrf2, SLC7A11, and GPX4, key components of the Nrf2/SLC7A11/GSH/GPX4 signaling pathway that protects against ferroptosis. Rescue experiments with ferroptosis inhibitors (liproxstatin-1) further confirmed the involvement of ferroptosis. These findings demonstrate that paclitaxel induces neurotoxicity by activating ferroptosis via suppression of the Nrf2/SLC7A11/GSH/GPX4 axis, providing potential therapeutic targets for preventing and treating paclitaxel-induced neurotoxicity.

1. Introduction

Chemotherapy is the most widely used cancer treatment; however, it remains a double-edged sword, often precipitating a spectrum of adverse complications. Among these, chemotherapy-induced neurotoxicity (CIN) emerges as one of the most prevalent and debilitating sequelae. For example, in breast cancer, the incidence of peripheral CIN in long-term chemotherapy patients reaches 58.4% [1], while the prevalence of chemotherapy-induced cognitive dysfunction is 61% [2]. Paclitaxel is a classic anticancer drug that has revolutionized the treatment of various malignancies since its approval and remains one of the most widely used therapeutic regimens to date. Several studies have demonstrated that paclitaxel exhibits significant neurotoxicity, with neurotoxic mechanisms including induction of apoptosis and DNA damage, activation of inflammatory responses and oxidative stress, and modulation of microtubule dysfunction [3]. However, effective interventions for preventing or treating CIN remain lacking. The current clinical management of CIN primarily relies on symptomatic medications such as gabapentin, pregabalin, and duloxetine. However, these drugs neither reverse existing neuronal damage nor halt the progressive deterioration of CIN symptoms. Gaining a deeper understanding of the mechanisms underlying paclitaxel-induced neurotoxicity is crucial for developing therapeutic agents to prevent and alleviate this neuropathy.

To confirm the neurotoxicity of paclitaxel, we evaluated the cytotoxic effects of paclitaxel in SH-SY5Y and HT-22 neuronal cells. The results revealed that paclitaxel exerted significant cytotoxic effects on both neuronal cell lines (Figure 1A). To explore the potential mechanism of paclitaxel-induced neurotoxicity, RNA-seq analysis was performed to identify paclitaxel-regulated genes and signaling pathways in HT-22 neuronal cells (Figure 1B,C). The materials and methods used in this study are available as Supplementary Data. Through Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of cellular processes with a total of 1332 differentially expressed genes between the control and paclitaxel groups (adjusted P < 0.05 and |log2foldchange| > 1), ferroptosis was among the top enriched pathways (Figure 1D). To confirm the importance of ferroptosis involvement in paclitaxel-induced neurotoxicity, we applied an independent ferroptosis gene set from GO-BP to conduct gene set enrichment analysis (GSEA). A consistent result was achieved in which the ferroptosis pathway was highly enriched in neurons following paclitaxel treatment (|NES| > 1 and P < 0.05) (Figure 1E). Furthermore, several canonical ferroptosis-related pathways (marked in red) were also ranked among the top 10 enriched pathways by GSEA enrichment analysis using KEGG and WikiPathways (Figure 1F,G), including peroxisome, nicotinate and nicotinamide metabolism, tricarboxylic acid (TCA) cycle, tryptophan metabolism, fatty acid biosynthesis and cholesterol metabolism with Bloch and Kandutsch-Russell pathways (|NES| > 1 and P < 0.05) (Figure 1H–M). These results indicated that paclitaxel-induced neurotoxicity was closely associated with ferroptosis.