Non-cytotoxic Concentration of Cisplatin Decreases Neuroplasticity-Related Proteins and Neurite Outgrowth Without Affecting the Expression of NGF in PC12 Cells

RNA-seq revealed the protective effect of Huangqi Guizhi Wuwu Decoction against cisplatin induced PC12 cell injury

BACKGROUND

Chemotherapy-induced peripheral neuropathy not only affects the tolerability of chemotherapy, but also causes intolerable and prolonged neuropathic pain in cancer patients. Currently, duloxetine is the only drug used to treat chemotherapy-induced peripheral neuropathy. However, the clinical use of this drug still faces several challenges. Therefore, we focused on traditional Chinese medicine to find an effective and safe alternative medicine. Huangqi Guizhi Wuwu Decoction is a traditional Chinese medicine that has been clinically used for treating nerve pain for thousands of years. This study aimed to investigate the neuroprotective effect of Huangqi Guizhi Wuwu Decoction on cisplatin-induced nerve injury in PC12 cells and to elucidate its potential mechanism of action.

METHODS

Huangqi Guizhi Wuwu Decoction-containing serum and blank serum were prepared from a rat model. The protective effects of Huangqi Guizhi Wuwu Decoction on cisplatin (10 µmol/L)-induced PC12 cell injury were assessed by a Cell Counting Kit-8 assay. RNA expression in Huangqi Guizhi Wuwu Decoction-protected PC12 cells was analyzed using RNA-seq, and subsequently, differentially expressed genes were further analyzed using Gene Ontology and Gene Set Enrichment Analysis.

RESULTS

The Cell Counting Kit-8 results showed that pretreatment of PC12 cells with Huangqi Guizhi Wuwu Decoction-containing serum (5%, 10%, 15%) significantly increased cells' viability to 10 µmol/L cisplatin-induced cell death. RNA-seq analysis revealed 843 differentially expressed genes in the chemotherapy-induced peripheral neuropathy group and 249 in the Huangqi Guizhi Wuwu Decoction group. The gene set enrichment analysis results in this study suggest that Huangqi Guizhi Wuwu Decoction may treat chemotherapy-induced peripheral neuropathy by enhancing axon guidance.

CONCLUSIONS

This study provides valuable evidence for using Huangqi Guizhi Wuwu Decoction in treating chemotherapy-induced peripheral neuropathy, partially achieved by improving axon guidance pathways.

Arc-Mediated Synaptic Plasticity Regulates Cognitive Function in a Migraine Mouse Model

Previous clinical and basic studies have shown that migraine is associated with cognitive impairment, anxiety, and depression. It severely affects the quality of life. In this study, C57BL/6 mice were randomly divided into four groups: IS group, IS+M group, and IS+S group with repeated application of dural inflammatory soup (IS) stimulation to establish a migraine model, followed by PBS, memantine, and sumatriptan interventions, respectively; the blank control group underwent the same treatment procedure but with PBS instead of IS and intervention drugs. The cognitive function of the mice was used as the main outcome indicator. After application of the IS, mice showed reduced pain threshold for mechanical stimulation, decreased learning memory capacity, attention deficit, a reduced number of dendritic spines in hippocampal neurons, and altered synaptic ultrastructure. The cognitive function indexes of mice in the IS+M group recovered with changes in Arc protein expression to a level not statistically different from that of the Control group, while the IS and IS+S groups remained at lower levels. The present results suggest that Arc-mediated synaptic plasticity may be an essential mechanism of cognitive dysfunction in migraine.

Investigation of effects of quercetin and low-level laser therapy in cisplatin-induced in vitro peripheral neuropathy model

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the dose-dependent side effects of cisplatin. The loss of sensory neurons is observed in CIPN. There are many methods to minimalize CIPN symptoms such as pharmacological agents and photobiostimulation but the mechanisms of these methods are unclear. Our study is aimed at determining the effects of quercetin and low-level laser therapy (LLLT) in undifferentiated and nerve growth factor-differentiated PC12 cells in cisplatin-induced peripheral neuropathy. PC12 cells with cisplatin were co-treated with quercetin and LLLT (diode pumped all-solid-state laser, 670 nm, output 500 mW, and the laser beam surface area was 1.96 cm2). The effects of quercetin and LLLT on GAP-43 and Synapsin I expressions were analyzed by real-time PCR, cell viability was assessed by MTT assay, Annexin and dead assay measured the induction of apoptosis, the alterations in mitopotential were assessed by mitopotential assay, and lactate dehydrogenase activity in cells was analyzed. All experiment data were analyzed by the Tukey test and applied as a post hoc test, and statistical evaluation was made. Our results indicated that cisplatin increased apoptosis (24,210 ± 2189, 46,504 ± 8246) cells, mitochondrial dysfunction (44,312 ± 0.751, 68,788 ± 1271), and LDH activity (62,821 ± 8245, 87,838 ± 8116). Furthermore, it decreased cell viability (42,447 ± 1780, 36,140 ± 3682) and inhibited GAP-43 and Synapsin I genes in undifferentiated and differentiated PC12 cells. However, apoptosis, the alterations in mitopotential, and lactate dehydrogenase activity decreased by applications of quercetin and LLLT. It has been recommended that quercetin and low-level laser therapy roles on cisplatin-induced peripheral neuropathy should be investigated in vivo, and the relationship between quercetin and low-level laser therapy should be molecular.

Neuron Compatibility and Antioxidant Activity of Barium Titanate and Lithium Niobate Nanoparticles

The biocompatibility and the antioxidant activity of barium titanate (BaTiO₃) and lithium niobate (LiNbO₃) were investigated on a neuronal cell line, the PC12, to explore the possibility of using piezoelectric nanoparticles in the treatment of inner ear diseases, avoiding damage to neurons, the most delicate and sensitive human cells. The cytocompatibility of the compounds was verified by analysing cell viability, cell morphology, apoptotic markers, oxidative stress and neurite outgrowth. The results showed that BaTiO₃ and LiNbO₃ nanoparticles do not affect the viability, morphological features, cytochrome c distribution and production of reactive oxygen species (ROS) by PC12 cells, and stimulate neurite branching. These data suggest the biocompatibility of BaTiO₃ and LiNbO₃ nanoparticles, and that they could be suitable candidates to improve the efficiency of new implantable hearing devices without damaging the neuronal cells.

Implantable Drug Reservoir Devices for Inner Ear Delivery of Pharmacotherapeutics

Objective

Cisplatin is a platinum-based chemotherapeutic drug that secondarily induces toxicity in inner ear sensory epithelia, contributing to auditory and vestibular dysfunction. We describe the creation of a drug reservoir device (DRD) to combat this ototoxicity for the duration of chemotherapy. As ototoxic side effects of chemotherapy may limit an oncologist’s ability to prescribe first-line agents such as cisplatin, mitigating such devastating effects through prolonged topical therapy would be tremendously valuable.

Study Design

We investigated (1) the ability of an electrospun polylactic acid DRD to provide prolonged delivery of the posited otoprotectant metformin and (2) the development of an in vitro model utilizing Sh-Sy5y human neuroblastoma cells to assess the efficacy of metformin in reducing cisplatin-induced toxicity.

Setting

Neurophysiology laboratory.

Methods

Basic science experiments were performed to assess DRD properties and metformin’s effects on cisplatin toxicity in culture.

Results

We found that DRDs with increasing polylactic acid concentrations exhibited metformin release for up to 8 weeks. In modeling elution across the round window in vitro, continued elution of metformin was observed for at least 6 weeks, as quantified by spectrophotometry. Unfortunately, metformin did not exhibit protective efficacy in this model using Sh-Sy5y cells.

Conclusion

While metformin was not found to be protective in Sh-Sy5y cells, these results suggest that an electrospun DRD can provide a tailorable drug delivery system providing medication for the duration of chemotherapy treatment. This represents a novel drug delivery system and efficacy screening assay with broad clinical applications in personalized delivery of inner ear therapies.

Overview of cisplatin-induced neurotoxicity and ototoxicity, and the protective agents

Cisplatin has dramatically improved the survival rate of cancer patients, but it has also increased the prevalence of hearing and neurological deficits in this population. Cisplatin induces ototoxicity, peripheral (most prevalent) and central (rare) neurotoxicity. This review addresses the ototoxicity and the neurotoxicity associated with cisplatin-based chemotherapy, providing an integrated view of the potential protective agents that have been evaluated in vitro, in vivo and in clinical trials, their targets and mechanisms of protection and their effects on the antitumor activity of cisplatin. So far, the findings are insufficient to support the use of any oto- or neuroprotective agent before, during or after cisplatin chemotherapy. Despite their promising effects in vitro and in animal studies, many agents have not been evaluated in clinical trials. Additionally, the clinical trials have limitations concerning the sample size, controls, measurement, heterogeneous groups, several arms of treatment, short follow-up or no blinding. Besides that, for most agents, the effects on the antitumor activity of cisplatin have not been evaluated in tumor-bearing animals, which discourages clinical trials. Further well-designed randomized controlled clinical trials are necessary to definitely demonstrate the effectiveness of the oto- or neuroprotective agents proposed by animal and in vitro studies.

Caffeic Acid Phenethyl Ester (CAPE) Protects PC12 Cells Against Cisplatin-Induced Neurotoxicity by Activating the AMPK/SIRT1, MAPK/Erk, and PI3k/Akt Signaling Pathways

Peripheral sensory neuropathy (PSN) is a well-known side effect of cisplatin characterized by axonal damage. In the early stage of neurotoxicity, cisplatin affects proteins that modulate neurite outgrowth and neuroplasticity, without inducing mitochondrial damage or apoptosis. There are no preventive therapies for cisplatin-induced peripheral neuropathy; therefore, measures to improve axonal growth and connectivity would be beneficial. Caffeic acid phenethyl ester (CAPE) is a bioactive component of propolis with neurotrophic and neuroprotective activities. We have recently showed that CAPE protects against cisplatin-induced neurotoxicity by activating NGF high-affinity receptors (trkA) and inducing neuroplasticity. We have now assessed other potential early targets of cisplatin and additional mechanisms involved in the neuroprotection of CAPE. Cisplatin reduced axonal cytoskeletal proteins (F-actin and β-III-tubulin) without inducing oxidative damage in PC12 cells. It also reduced energy-related proteins (AMPK α, p-AMPK α, and SIRT1) and glucose uptake. At this stage of neurotoxicity, glutamate excitotoxicity is not involved in the toxicity of cisplatin. CAPE attenuated the downregulation of the cytoskeleton and energy-related markers as well as SIRT1 and phosphorylated AMPK α. Moreover, the neuroprotective mechanism of CAPE also involves the activation of the neurotrophic signaling pathways MAPK/Erk and PI3k/Akt. The PI3K/Akt pathway is involved in the upregulation of SIRT1 induced by CAPE, but not in the upregulation of cytoskeletal proteins. Altogether, these findings suggest that the neuroprotective effect of CAPE against cisplatin-induced neurotoxicity involves both (a) a neurotrophic mechanism that mimics the mechanism triggered by the NGF itself and (b) a non-neurotrophic mechanism that upregulates the cytoskeletal proteins.

Caffeic Acid Phenethyl Ester (CAPE) Protects PC12 Cells from Cisplatin-Induced Neurotoxicity by Activating the NGF-Signaling Pathway

Cisplatin is a highly effective chemotherapeutic drug that is toxic to the peripheral nervous system. Findings suggest that axons are early targets of the neurotoxicity of cisplatin. Although many compounds have been reported as neuroprotective, there is no effective treatment against the neurotoxicity of cisplatin. Caffeic acid phenethyl ester (CAPE) is a propolis component with neuroprotective potential mainly attributed to antioxidant and anti-inflammatory mechanisms. We have recently demonstrated the neurotrophic potential of CAPE in a cellular model of neurotoxicity related to Parkinson's disease. Now, we have assessed the neurotrophic and neuroprotective effects of CAPE against cisplatin-induced neurotoxicity in PC12 cells. CAPE (10 μM) attenuated the inhibition of neuritogenesis and the downregulation of markers of neuroplasticity (GAP-43, synapsin I, synaptophysin, and 200-kD neurofilament) induced by cisplatin (5 μM). This concentration of cisplatin does not affect cell viability, and it was used in order to assess the early neurotoxic events triggered by cisplatin. When a lethal dose of cisplatin was used (IC50 = 32 μM), CAPE (10 μM) increased cell viability. The neurotrophic effect of CAPE is not dependent on NGF nor is it additive to the effect of NGF, but it might involve the activation of the NGF-high-affinity receptors (trkA). The involvement of other neurotrophin receptors such as trkB and trkC is unlikely. This is the first study to demonstrate the protective potential of CAPE against the neurotoxicity of cisplatin and to suggest the involvement of trkA receptors in the neuroprotective mechanism of CAPE. Based on these findings, the beneficial effect of CAPE on cisplatin-induced peripheral neuropathy should be further investigated.