Paclitaxel neurotoxicity is triggered by epidermal EG5-dependent microtubule fasciculation and X-ROS formation.

Taxanes are frontline chemotherapeutics that stabilize microtubules, induce mitotic arrest, and drive tumor remission. However, their off-target effects in healthy tissues, most notably cutaneous axon degeneration underlying chemotherapy-induced peripheral neuropathy (CIPN), remain poorly understood. Here, we show that paclitaxel induces microtubule fasciculation in epidermal keratinocytes through the mitotic kinesin Eg5, thereby initiating CIPN. Mechanistically, paclitaxel enhances Eg5-dependent fasciculation of detyrosinated (stabilized) microtubules, which constrict and breach the nuclear lamina. This deformation triggers tension-dependent NADPH oxidase-mediated nuclear ROS (X-ROS) formation upstream of transcription, a pathway we previously demonstrated drives sensory axon degeneration. Employing a cross-species framework spanning zebrafish, mice, human skin biopsies, and a breast adenocarcinoma cell line, we uncover a conserved paclitaxel-Eg5 mechanism leading to fasciculation of stable microtubules in both healthy epidermis and cancer cells. These findings highlight the dualistic nature of paclitaxel action and underscore the challenge of preserving anticancer efficacy while preventing neurotoxic side effects.