Towards a mechanistic understanding of axon transport and endocytic changes underlying paclitaxel-induced peripheral neuropathy

The Molecular and Clinical Impact of Atorvastatin Exposure on Paclitaxel Neurotoxicity in Sensory Neurons and Cancer Patients

Recent evidence suggests that atorvastatin exacerbates paclitaxel neurotoxicity via P-glycoprotein inhibition. We used a translational approach to investigate if atorvastatin or simvastatin exacerbates (i) paclitaxel neurotoxicity in human sensory neurons and (ii) paclitaxel-induced peripheral neuropathy (PIPN) in cancer patients. Paclitaxel neurotoxicity was assessed by quantifying neuronal networks of human induced pluripotent stem cell-derived sensory neurons (iPSC-SNs) with and without atorvastatin or simvastatin exposure. We estimated the odds ratio (OR) of early paclitaxel discontinuation due to PIPN in a nationwide cohort of paclitaxel-treated women (2014-2018), comparing atorvastatin users to simvastatin users and nonusers of statins. Only the highest concentration of atorvastatin (100 nM) significantly exacerbated paclitaxel neurotoxicity in iPSC-SNs (p < 0.05). Among 576 paclitaxel-treated women, atorvastatin use was not significantly associated with early paclitaxel discontinuation due to PIPN, with adjusted ORs of 0.80 [95% confidence interval (CI) 0.34-1.88] compared with simvastatin, and 1.24 [95% CI 0.44-3.53] compared with nonuse. Supplementary analyses showed varying but statistically nonsignificant results. Our in vitro findings suggest that atorvastatin, not simvastatin, significantly worsens paclitaxel neurotoxicity. However, no link was found between atorvastatin use and early paclitaxel discontinuation due to PIPN. Larger, well-designed studies are required to clarify the discrepancy between in vitro and clinical data and the inconsistencies with previous clinical evidence.

Preventing neuropathy and improving anti-cancer chemotherapy with a carbazole-based compound

Advances in cancer treatment have led to a steady increase in the rate of disease remission. However, while many treatment-related adverse effects gradually resolve after therapy, chemotherapy-induced peripheral neuropathy (CIPN) often persists, with no means of prevention or direct treatment available. Herein, we present Carba1, a novel bi-functional carbazole that mitigates neuropathy through two distinct mechanisms. First, by interacting with tubulin, Carba1 reduces the required dose of taxanes, widely used chemotherapy drugs notorious for their toxic side effects, including CIPN. Second, Carba1 activates nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the NAD salvage pathway, triggering a metabolic rewiring that enhances the resilience of neurons and Schwann cells against chemotherapy-induced toxicity. We demonstrate the neuroprotective efficacy of Carba1 both in vitro, against neurotoxicity induced by paclitaxel (PTX), cisplatin, and bortezomib, and in vivo in a rat model of PTX-induced neuropathy. Importantly, we establish that Carba1 does not compromise the therapeutic efficacy of PTX nor promotes tumor growth. Comparative analyses of Carba1 derivatives further suggest the potential of designing compounds with either dual synergistic and neuroprotective activity or exclusive neuroprotective properties. Altogether, our findings position Carba1 as a promising therapeutic candidate for preventing CIPN, with the potential, if successfully translated to clinical settings, to improve both the quality of life and treatment outcome for cancer patients.

StableMARK-decorated microtubules in cells have expanded lattices

Microtubules are crucial in cells and are regulated by various mechanisms like posttranslational modifications, microtubule-associated proteins, and tubulin isoforms. Recently, the conformation of the microtubule lattice has also emerged as a potential regulatory factor, but it has remained unclear to what extent different lattices co-exist within the cell. Using cryo-electron tomography, we find that, while most microtubules have a compacted lattice (∼41 Å monomer spacing), approximately a quarter of the microtubules displayed more expanded lattice spacings. The addition of the microtubule-stabilizing agent Taxol increased the lattice spacing of all microtubules, consistent with results on reconstituted microtubules. Furthermore, correlative cryo-light and electron microscopy revealed that the stable subset of microtubules labeled by StableMARK, a marker for stable microtubules, predominantly displayed a more expanded lattice spacing (∼41.9 Å), further suggesting a close connection between lattice expansion and microtubule stability. The coexistence of different lattices and their correlation with stability implicate lattice spacing as an important factor in establishing specific microtubule subsets.

Translation of paclitaxel-induced peripheral neurotoxicity from mice to patients: the importance of model selection

ABSTRACT

Paclitaxel-induced peripheral neurotoxicity (PIPN) is a potentially dose-limiting side effect in anticancer chemotherapy. Several animal models of PIPN exist, but their results are sometimes difficult to be translated into the clinical setting. We compared 2 widely used PIPN models characterized by marked differences in their methodologies. Female C57BL/6JOlaHsd mice were used, and they received only paclitaxel vehicle (n = 38) or paclitaxel via intravenous injection (n = 19, 70 mg/kg) once a week for 4 weeks (Study 1) or intraperitoneally (n = 19, 10 mg/kg) every 2 days for 7 times (Study 2). At the end of treatment and in the follow-up, mice underwent behavioral and neurophysiological assessments of PIPN. At the same time points, some mice were killed and dorsal root ganglia, skin, and sciatic and caudal nerve samples underwent pathological examination. Serum neurofilament light levels were also measured. The differences in the neurotoxicity parameters were analyzed using a nonparametric Mann-Whitney test, with significance level set at P < 0.05. Study 1 showed significant and consistent behavioral, neurophysiological, pathological, and serological changes induced by paclitaxel administration at the end of treatment, and most of these changes were still evident in the follow-up period. By contrast, study 2 evidenced only a transient small fiber neuropathy, associated with neuropathic pain. Our comparative study clearly distinguished a PIPN model recapitulating all the clinical features of the human condition and a model showing only small fiber neuropathy with neuropathic pain induced by paclitaxel.

Ursolic acid alleviates paclitaxel-induced peripheral neuropathy through PPARγ activation

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) reduces the overall quality of life and leads to interruption of chemotherapy. Ursolic acid, a triterpenoid naturally which presents in fruit peels and in many herbs and spices, can function as a peroxisome proliferator-activated receptor γ (PPARγ) agonist, and has been widely used as an herbal medicine with a wide spectrum of pharmacological activities, including anti-cancer, anti-inflammatory and neuroprotective effect.

METHODS

We used a phenotypic drug screening approach to identify ursolic acid as a potential neuroprotective drug in vitro and in vivo and carried out additional biochemical experiments to identify its mechanism of action.

RESULTS

Our study demonstrated that ursolic acid reduced neurotoxicity and cell apoptosis induced by pacilitaxel, resulting in an improvement of CIPN. Moreover, we explored the potential mechanisms of ursolic acid on CIPN. As a result, ursolic acid inhibited CHOP (C/EBP Homologous Protein) expression, indicating the endoplasmic reticulum (ER) stress suppression, and regulating CHOP related apoptosis regulator (the Bcl2 family) to reverse pacilitaxel induced apoptosis. Moreover, we showed that the therapeutic effect of ursolic acid on the pacilitaxel-induced peripheral neuropathy is PPARγ dependent.

CONCLUSIONS

Taken together, the present study suggests ursolic acid has potential as a new PPARγ agonist targeting ER stress-related apoptotic pathways to ameliorate pacilitaxel-induced peripheral neuropathic pain and nerve injury, providing new clinical therapeutic method for CIPN.

Microtubule-Targeting Agents: Disruption of the Cellular Cytoskeleton as a Backbone of Ovarian Cancer Therapy

Microtubules are dynamic polymers composed of α- and β-tubulin heterodimers. Microtubules are universally conserved among eukaryotes and participate in nearly every cellular process, including intracellular trafficking, replication, polarity, cytoskeletal shape, and motility. Due to their fundamental role in mitosis, they represent a classic target of anti-cancer therapy. Microtubule-stabilizing agents currently constitute a component of the most effective regimens for ovarian cancer therapy in both primary and recurrent settings. Unfortunately, the development of resistance continues to present a therapeutic challenge. An understanding of the underlying mechanisms of resistance to microtubule-active agents may facilitate the development of novel and improved approaches to this disease.