Fluocinolone Acetonide Enhances Anterograde Mitochondria Trafficking and Promotes Neuroprotection against Paclitaxel-Induced Peripheral Neuropathy

Phytic Acid Maintains Peripheral Neuron Integrity and Enhances Survivability against Platinum-Induced Degeneration via Reducing Reactive Oxygen Species and Enhancing Mitochondrial Membrane Potential

Phytic acid (PA) has been reported to possess anti-inflammatory and antioxidant properties that are critical for neuroprotection in neuronal disorders. This raises the question of whether PA can effectively protect sensory neurons against chemotherapy-induced peripheral neuropathy (CIPN). Peripheral neuropathy is a dose-limiting side effect of chemotherapy treatment often characterized by severe and abnormal pain in hands and feet resulting from peripheral nerve degeneration. Currently, there are no effective treatments available that can prevent or cure peripheral neuropathies other than symptomatic management. Herein, we aim to demonstrate the neuroprotective effects of PA against the neurodegeneration induced by the chemotherapeutics cisplatin (CDDP) and oxaliplatin. Further aims of this study are to provide the proposed mechanism of PA-mediated neuroprotection. The neuronal protection and survivability against CDDP were characterized by axon length measurements and cell body counting of the dorsal root ganglia (DRG) neurons. A cellular phenotype study was conducted microscopically. Intracellular reactive oxygen species (ROS) was estimated by fluorogenic probe dichlorofluorescein. Likewise, mitochondrial membrane potential (MMP) was assessed by fluorescent MitoTracker Orange CMTMRos. Similarly, the mitochondria-localized superoxide anion radical in response to CDDP with and without PA was evaluated. The culture of primary DRG neurons with CDDP reduced axon length and overall neuronal survival. However, cotreatment with PA demonstrated that axons were completely protected and showed increased stability up to the 45-day test duration, which is comparable to samples treated with PA alone and control. Notably, PA treatment scavenged the mitochondria-specific superoxide radicals and overall intracellular ROS that were largely induced by CDDP and simultaneously restored MMP. These results are credited to the underlying neuroprotection of PA in a platinum-treated condition. The results also exhibited that PA had a synergistic anticancer effect with CDDP in ovarian cancer in vitro models. For the first time, PA's potency against CDDP-induced PN is demonstrated systematically. The overall findings of this study suggest the application of PA in CIPN prevention and therapeutic purposes.

Electrical stimulation enhances mitochondrial trafficking as a neuroprotective mechanism against chemotherapy-induced peripheral neuropathy

Electrical stimulation (ESTIM) has shown to be an effective symptomatic treatment to treat pain associated with peripheral nerve damage. However, the neuroprotective mechanism of ESTIM on peripheral neuropathies is still unknown. In this study, we identified that ESTIM has the ability to enhance mitochondrial trafficking as a neuroprotective mechanism against chemotherapy-induced peripheral neuropathies (CIPNs). CIPN is a debilitating and painful sequalae of anti-cancer chemotherapy treatment which results in degeneration of peripheral nerves. Mitochondrial dynamics were analyzed within axons in response to two different antineoplastic mechanisms by chemotherapy drug treatments paclitaxel and oxaliplatin in vitro. Mitochondrial trafficking response to chemotherapy drug treatment was observed to decrease in conjunction with degeneration of distal axons. Using low-frequency ESTIM, we observed enhanced mitochondrial trafficking to be a neuroprotective mechanism against CIPN. This study confirms ESTIM enhances regeneration of peripheral nerves by increased mitochondrial trafficking.

Mitochondrial trafficking as a protective mechanism against chemotherapy drug-induced peripheral neuropathy: Identifying the key site of action

AIMS

Chemotherapy induced peripheral neuropathy (CIPN) is a common side effect seen in patients who have undergone most chemotherapy treatments to which there are currently no treatment methods. CIPN has been shown to cause axonal degeneration leading to Peripheral Neuropathy (PN), which can lead to major dosage reduction and may prevent further chemotherapy treatment due to oftentimes debilitating pain. Previously, we have determined the site-specific action of Paclitaxel (PTX), a microtubule targeting agent, as well as the neuroprotective effect of Fluocinolone Acetonide (FA) against Paclitaxel Induced Peripheral Neuropathy (PIPN).

MAIN METHODS

Mitochondrial trafficking analysis was determined for all sample sets, wherein FA showed enhanced anterograde (axonal) mitochondrial trafficking leading to neuroprotective effects for all samples.

KEY FINDINGS

Using this system, we demonstrate that PTX, Monomethyl auristatin E (MMAE), and Vincristine (VCR), are toxic at clinically prescribed levels when treated focally to axons. However, Cisplatin (CDDP) was determined to have a higher toxicity when treated to cell bodies. Although having different targeting mechanisms, the administration of FA was determined to have a significant neuroprotective effect for against all chemotherapy drugs tested.

SIGNIFICANCE

This study identifies key insights regarding site of action and neuroprotective strategies to further development as potential therapeutics against CIPN. FA was treated alongside each chemotherapy drug to identify the neuroprotective effect against CIPN, where FA was found to be neuroprotective for all drugs tested. This study found that treatment with FA led to an enhancement in the anterograde movement of mitochondria based on fluorescent imaging.