Paclitaxel-induced Neurotoxicity Research Articles

Effect of Metformin on Epidermal Neural Crest Stem Cells and Their Potential Application in Ameliorating Paclitaxel-induced Neurotoxicity Phenotype.

Epidermal Neural Crest Stem Cells (EPI-NCSCs) have emerged as prospective ideal candidates to meet the fundamental requirements of cell-based therapies in neurodegenerative disorders. The present study aimed to identify the potential of metformin in driving EPI-NCSCs to neuronal/glial differentiation and express neurotrophic factors as well as assess their therapeutic potential for mitigating the main behavioral manifestations of chemotherapy-induced neurotoxicity (CIN). EPI-NCSCs were extracted from the bulge region of hair follicle. Following expansion, transcript and protein expression profiles of key markers for stemness (Nestin, EGR-1, SOX-2 and 10), neurotrophic activity (BDNF, GDNF, NGF, FGF-2, and IL-6), and neuronal (TUB3, DCX, NRF and NeuN) and glial (PDGFRα, NG2, GFAP, and MBP) differentiation were determined on days 1 and 7 post-treatment with 10 and 100μM metformin using real time-PCR and immunocytochemistry methods. Then, the in vivo function of metformin-treated stem cells was evaluated in the context of paclitaxel CIN. To do so, thermal hyperalgesia, mechanical allodynia, and spatial learning and memory tests were evaluated by Hotplate, Von Frey, and Morris water maze tests. Our result indicated that exposure of EPI-NCSCs to metformin was associated with progressive decline in stemness markers and enhanced expression levels of several neurotrophic, neuron and oligodendrocyte-specific markers. Further, it was observed that intranasal metformin-treated EPI-NCSCs improved the cognitive impairment, and mechanical and thermal hypersensitivity induced by paclitaxel in rats. Collectively, we reasoned that metformin pretreatment of EPI-NCSCs might further enhance their therapeutic benefits against CIN.

Efficient syntheses of KLS-13019 using palladium mediated cross couplings

KLS-13019 is a structural analogue of cannabidiol, that shows improved bioavailability and potency in both preventing and reversing paclitaxel-induced neurotoxicity in vitro and in vivo. KLS-13019 was selected as a development candidate and attention was turned to development of a scalable synthesis. The original synthesis of KLS-13019 was not efficient, regioselective, or high yielding. Two new syntheses are reported that make use of the palladium catalyzed cross couplings to a chemically advanced intermediate 5, dramatically shortening (3–4 steps) and improving the overall yield. In addition, a convenient one pot Boc-cleavage and acetylation procedure is described to avoid impurities generated from a step-wise process.

2,6-Disubstituted Piperidine Alkaloids with Neuroprotective Activity from Hippobroma longiflora.

Three new alkaloids, hipporidine A (1: ), hipporidine B (2: ), and (-)-lobeline N-oxide (3: ), were discovered from the whole plant of Hippobroma longiflora together with five known compounds (4: -8: ). Their 2,6-disubstituted piperidine structures were established based on the HRESIMS, NMR (COSY, HMBC, HSQC, NOESY), and UV spectroscopic data. Hipporidines A (1: ) and B (2: ) possess a rare 1,3-oxazinane moiety. Compound 3: is the N-oxide derivative of (-)-lobeline (6: ). Moreover, the absolute configuration of norlobeline (5: ) was established by single-crystal X-ray diffraction analysis. Three major secondary metabolites (6: -8: ) were evaluated for their neuroprotective effect against paclitaxel-induced neurotoxicity. Consequently, pretreatment with compound 8: at a concentration of 1.0 µM displayed significant attenuation on paclitaxel-damaged neurite outgrowth of dorsal root ganglion neurons without interfering with the cytotoxicity of paclitaxel on cervical cancer SiHa cells.

Hinokitiol functions as a ferroptosis inhibitor to confer neuroprotection.

The intrinsic link of ferroptosis to neurodegeneration, such as Parkinson's disease and Alzheimer's disease, has set promises to apply ferroptosis inhibitors for treatment of neurodegenerative disorders. Herein, we report that the natural small molecule hinokitiol (Hino) functions as a potent ferroptosis inhibitor to rescue neuronal damages in vitro and in vivo. The action mechanisms of Hino involve chelating irons and activating cytoprotective transcription factor Nrf2 to upregulate the antioxidant genes including solute carrier family 7 member 11, glutathione peroxidase 4 and Heme oxygenase-1. In vivo studies demonstrate that Hino rescues the deficits of locomotor activity and neurodevelopment in zebrafishes. In addition, Hino shows the efficient blood-brain barrier permeability in mice, supporting the application of Hino for brain disorders. Paclitaxel is one of the most widely used broad-spectrum antineoplastic agents. However, its neurotoxic side effect is a severe concern. We demonstrate that the neurotoxicity of paclitaxel is ferroptosis-related and Hino also alleviates the paclitaxel-induced neurotoxicity without compromising its cytotoxicity to cancer cells. Hino also salvages the neurobehavioral impairment by paclitaxel in zebrafishes. Collectively, the discovery of Hino as a novel ferroptosis inhibitor and disclosure of its action mechanisms establish a foundation for the further development of Hino as a neuroprotective agent.

Inhibitors of Mitochondrial Human Carbonic Anhydrases VA and VB as a Therapeutic Strategy against Paclitaxel-Induced Neuropathic Pain in Mice.

Neuropathy development is a major dose-limiting side effect of anticancer treatments that significantly reduces patient’s quality of life. The inadequate pharmacological approaches for neuropathic pain management warrant the identification of novel therapeutic targets. Mitochondrial dysfunctions that lead to reactive oxygen species (ROS) increase, cytosolic Ca2+ imbalance, and lactate acidosis are implicated in neuropathic pain pathogenesis. It has been observed that in these deregulations, a pivotal role is played by the mitochondrial carbonic anhydrases (CA) VA and VB isoforms. Hence, preclinical studies should be conducted to assess the efficacy of two novel selenides bearing benzenesulfonamide moieties, named 5b and 5d, and able to inhibit CA VA and VB against paclitaxel-induced neurotoxicity in mice. Acute treatment with 5b and 5d (30–100 mg/kg, per os – p.o.) determined a dose-dependent and long-lasting anti-hyperalgesic effect in the Cold plate test. Further, repeated daily treatment for 15 days with 100 mg/kg of both compounds (starting the first day of paclitaxel injection) significantly prevented neuropathic pain development without the onset of tolerance to the anti-hyperalgesic effect. In both experiments, acetazolamide (AAZ, 100 mg/kg, p.o.) used as the reference drug was partially active. Moreover, ex vivo analysis demonstrated the efficacy of 5b and 5d repeated treatments in reducing the maladaptive plasticity that occurs to glia cells in the lumbar portion of the spinal cord and in improving mitochondrial functions in the brain and spinal cord that were strongly impaired by paclitaxel-repeated treatment. In this regard, 5b and 5d ameliorated the metabolic activity, as observed by the increase in citrate synthase activity, and preserved an optimal mitochondrial membrane potential (ΔΨ) value, which appeared depolarized in brains from paclitaxel-treated animals. In conclusion, 5b and 5d have therapeutic and protective effects against paclitaxel-induced neuropathy without tolerance development. Moreover, 5b and 5d reduced glial cell activation and mitochondrial dysfunction in the central nervous system, being a promising candidate for the management of neuropathic pain and neurotoxicity evoked by chemotherapeutic drugs.

TMI-1, TNF-α-Converting Enzyme Inhibitor, Protects Against Paclitaxel-Induced Neurotoxicity in the DRG Neuronal Cells In Vitro.

Background: Chemotherapy-induced peripheral neuropathy (CIPN) negatively impacts cancer survivors’ quality of life and is challenging to treat with existing drugs for neuropathic pain. TNF-α is known to potentiate TRPV1 activity, which contributes to CIPN. Here, we assessed the role of TMI-1, a TNF-α-converting enzyme inhibitor, in paclitaxel (PAC)-induced neurotoxicity in dorsal root ganglion (DRG) cells. Materials and Methods: Immortalized DRG neuronal 50B11 cells were cultured and treated with PAC or PAC with TMI-1 following neuronal differentiation. Cell viability, analysis of neurite growth, immunofluorescence, calcium flow cytometry, western blotting, quantitative RT-PCR, and cytokine quantitation by ELISA were performed to determine the role of TMI-1 in neurotoxicity in neuronal cells. Results: PAC administration decreased the length of neurites and upregulated the expression of TRPV1 in 50B11 cells. TMI-1 administration showed a protective effect by suppressing inflammatory signaling, and secretion of TNF-α. Conclusion: TMI-1 partially protects against paclitaxel-induced neurotoxicity by reversing the upregulation of TRPV1 and decreasing levels of inflammatory cytokines, including TNF-α, IL-1β, and IL-6 in neuronal cells.

Ketogenic diet prevents paclitaxel-induced neuropathic nociception through activation of PPARγ signalling pathway and inhibition of neuroinflammation in rat dorsal root ganglion.

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect during the course of cancer treatment, which is mainly manifested as a series of sensory abnormalities. At present, there are no recommended prevention or treatment strategies, and the underlying mechanisms are unclear. The ketogenic diet (KD), a special diet that is high in fat and low in carbohydrate intake, shows good therapeutic potential in children with epilepsy. In this study, it was found that KD significantly prevented paclitaxel-induced neuropathic nociception. Using the GSE113941 database, 281 differentially expressed genes (DEGs) were found in an animal model of CIPN and controls. The DEGs were mainly enriched in peroxisome proliferator activated receptor (PPAR) and oxidative phosphorylation signalling pathways. As a main regulatory pathway of lipid metabolism, the PPARγ signalling pathway was significantly upregulated in the KD model. In addition, KD also inhibited the expression of pro-inflammatory cytokines and the TLR4/NF-κB signalling pathway in the dorsal root ganglion (DRG) in paclitaxel-treated rats. In vitro, rat primary DRG neurons were used to investigate the role of PPARγ in paclitaxel-induced neurotoxicity. It was found that PPARγ agonist rosiglitazone significantly protected DRG neurons against cell apoptosis and reactive oxygen species generation induced by paclitaxel administration. Therefore, KD is a prospective treatment option when applied as a dietary intervention in the prevention and treatment of paclitaxel-induced neuropathic nociception, possibly through the activation of PPARγ and its neuroprotective functions.

Weekly Paclitaxel-Induced Neurotoxicity in Breast Cancer: Outcomes and Dose Response.

Paclitaxel treatment produces significant peripheral neuropathy, but the time course of neuropathy development and outcomes are unclear. Dose reduction is the only strategy to prevent neurotoxicity, however, the impact of dose-reduction on neuropathy outcomes remains unknown. This study aimed to prospectively evaluated neuropathy development from weekly paclitaxel treatment and evaluate the impact of dose-reduction on post-treatment neuropathy outcomes. Breast cancer patients receiving paclitaxel (80mg/m2 ) weekly for 12-weeks were prospectively assessed using patient reported (Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity; FACTGOG-Ntx), clinical (Total Neuropathy Score clinical version; TNSc) and neurophysiological measures up to 12-months post completion. The impact of dose-reduction on post-treatment (3.6 ± 0.1 months) clinical and patient reported outcomes was evaluated in 105 weekly paclitaxel-treated patients. Significant neuropathy was present by 6-weeks across patient-reported, clinical, and objective neurophysiological assessments, increasing in prevalence and severity over the treatment course. Limited recovery occurred, with significant neuropathy being maintained up to 12 months (p < .05). Patients who received dose reduction had worse patient reported (FACT-GOG-Ntx: 40.2 ± .1.4) and clinical neuropathy outcomes (TNSc: 4.3 ± 0.4) compared to those who received the full dose (FACT-GOG-Ntx: 45.9 ± 0.9; TNSc: 3.3 ± 0.3, p < .05). Patients who ceased treatment early demonstrated the worse deficits (TNSc: 5.0 ± 0.6; FACT-GOG-Ntx: 37.3 ± 2.7) compared to those who received the complete dose (TNSc: 3.5 ± 0.3; FACT-GOG-Ntx: 45.3 ± 0.9, p < .05). Weekly paclitaxel produces symptomatic and objective neuropathy early in the treatment course which can persist. Dose reduction does not necessarily lead to more favorable neuropathy outcomes, with individual risk factors likely important in addition to cumulative dose. Weekly paclitaxel schedules are extensively used in breast cancer. Patients may develop symptomatic and objective neuropathy early in the treatment course, with these individuals requiring closer monitoring. Furthermore, neuropathy is a long-term sequela that may impact quality of life and require appropriate supportive services. Results suggest that dose reduction does not necessarily lead to better neuropathy outcomes. Understanding schedule-specific toxicity and risk factors for neuropathy will be critical to determining individualized treatment strategies and improving quality of life in breast cancer survivors.

Additional alkaloids from Zoanthus vietnamensis with neuroprotective and anti-angiogenic effects

A chemical investigation of the zoantharian Zoanthus vietnamensis, collected off Taiwan, yielded eleven new alkaloids, 7α-hydroxykuroshine J (1), 18β-hydroxykuroshine J (2), 5α-hydroxyzoanthenamine (3), 5β-hydroxyzoanthenamine (4), 14α-hydroxyzoanthenamine (5), 30-hydroxyzoanthenamine (6), 11-dehydroxy-18-epi-kuroshine A (7), 5α-hydroxykuroshine A (8), 7β-hydroxykuroshine A (9), 11-keto-oxyzoanthamine (10), and 30-hydroxyzoanthamine (11), along with eight known compounds (12–19). The structures of these compounds were identified by detailed spectroscopic data, including HRESIMS, IR, NMR, and UV spectra. All secondary metabolites isolated from Z. vietnamensis were investigated for the anti-angiogenic effect in human endothelial progenitor cells (EPCs). Compounds 6, 7, 11, and 13 exhibited mild anti-angiogenic effect by blocking cell growth and tube formation of EPCs. The neuroprotective potential of four major compounds 12, 14, 15, and 19 against paclitaxel-induced neurotoxicity was evaluated. Pretreatment of 14 and 15 protected paclitaxel-damaged neurite outgrowth of dorsal root ganglion (DRG) neurons, without interfering the cytotoxic activity of paclitaxel on cervical cancer SiHa cells.

Different types of components obtained from Monascus purpureus with neuroprotective and anti-inflammatory potentials.

The mold Monascus has been used as a natural food coloring agent and food additive for more than 1000 years in Asian countries. In Chinese herbology, it was also used for easing digestion and antiseptic effects. Through a thorough investigation of a citrinin-free strain: M. purpureus BCRC 38110, four azaphilones, three benzenoids, one benzofuranone, one 5',6'-dihydrospiro[isochromane-1,2'-pyran]-4'(3'H)-one derivative, two steroids, and six tetralones have been successfully identified. Among them, monapyridine A (1), monatetralones A-E (2-6), and monabenzofuranone (7) were first reported. Their structures were characterized by 1D and 2D NMR, UV, IR, and HRESIMS analyses. With a series of bioactivity screening, monascuspirolide B (14) and ergosterol peroxide (16) exhibited concentration-dependent attenuation of the paclitaxel-induced neurite damage of mouse dorsal root ganglion neurons. The interleukin (IL)-1β-induced release of inflammatory cytokines IL-8 and tumor necrosis factor (TNF)-α in human chondrosarcoma cells was inhibited by monapurpureusone (8) and monascuspirolide B (14). Altogether, M. purpureus BCRC 38110 possessed potentials as natural therapeutics against inflammatory osteoarthritis and paclitaxel-induced neurotoxicity.

Targeting Axon Integrity to Prevent Chemotherapy-Induced Peripheral Neuropathy.

Chemotherapy-induced peripheral neuropathy (CIPN) is an irreversible off-target adverse effect of many chemotherapeutic agents such as paclitaxel, yet its mechanism is poorly understood and no preventative measure is available. CIPN is characterized by peripheral nerve damages resulting in permanent sensory function deficits. Our recent unbiased genome-wide analysis revealed that heat shock protein (Hsp) 27 is part of a transcriptional network induced by axonal injury and highly enriched for genes involved in adaptive neuronal responses, particularly axonal regeneration. To examine if Hsp27 could prevent the occurrence of CIPN, we first demonstrated that paclitaxel-induced allodynia was associated directly with axonal degeneration in sensory neurons in a mouse model of CIPN. We therefore hypothesize that by preventing axonal degeneration could prevent the development of CIPN. We drove expression of human Hsp27 (hHsp27) specifically in neurons. Development of mechanical and thermal allodynia was prevented completely in paclitaxel-treated hHsp27 transgenic mice. Strikingly, hHsp27 protected against paclitaxel-induced neurotoxicity in vivo including degeneration of afferent nerve fibers, demyelination, mitochondrial swelling, apoptosis, and restored sensory nerve action potential. Finally, we delineated signaling cascades that link CIPN development to caspase 3 and RhoA/cofilin activation in sensory neurons and peripheral nerves. hHsp27 exerted anti-apoptotic effect and maintained axon integrity by restoring caspase 3 and RhoA expression to basal levels. Taken together, our data suggest that by preventing axonal degeneration might prove beneficial as anti-CIPN drugs, which represents an emerging research area for therapeutic development.

Synthetic lethality in CCNE1-amplified high grade serous ovarian cancer through combined inhibition of Polo-like kinase 1 and microtubule dynamics.

The taxanes are effective microtubule-stabilizing chemotherapy drugs that inhibit mitosis, induce apoptosis, and produce regression in a fraction of cancers that arise at many sites including the ovary. Novel therapeutic targets that augment taxane effects are needed to improve clinical chemotherapy response in CCNE1-amplified high grade serous ovarian cancer (HGSOC) cells. In this study, we conducted an siRNA-based kinome screen to identify modulators of mitotic progression in CCNE1-amplified HGSOC cells that may influence clinical paclitaxel response. PLK1 is overexpressed in many types of cancer, which correlates with poor prognosis. Here, we identified a novel synthetic lethal interaction of the clinical PLK1 inhibitor BI6727 and the microtubule-targeting drug paclitaxel in HGSOC cell lines with CCNE1-amplification and elucidated the underlying molecular mechanisms of this synergism. BI6727 synergistically induces apoptosis together with paclitaxel in different cell lines including a patient-derived primary ovarian cancer culture. Moreover, the inhibition of PLK1 reduced the paclitaxel-induced neurotoxicity in a neurite outgrowth assay. Mechanistically, the combinatorial treatment with BI6727/paclitaxel triggers mitotic arrest, which initiates mitochondrial apoptosis by inactivation of anti-apoptotic BCL-2 family proteins, followed by significant loss of the mitochondrial membrane potential and activation of caspase-dependent effector pathways. This conclusion is supported by data showing that BI6727/paclitaxel-co-treatment stabilizes FBW7, a component of SCF-type ubiquitin ligases that bind and regulate key modulators of cell division and growth including MCL-1 and Cyclin E. This identification of a novel synthetic lethality of PLK1 inhibitors and a microtubule-stabilizing drug has important implications for developing PLK1 inhibitor-based combination treatments in CCNE1-amplified HGSOC cells.

TRPV4 inhibition prevents paclitaxel-induced neurotoxicity in preclinical models

Paclitaxel is a cytotoxic drug which frequently causes sensory peripheral neuropathy in patients. Increasing evidence suggests that altered intracellular calcium (Ca2+) signals play an important role in the pathogenesis of this condition. In the present study, we examined the interplay between Ca2+ release channels in the endoplasmic reticulum (ER) and Ca2+ permeable channels in the plasma membrane in the context of paclitaxel mediated neurotoxicity. We observed that in small to medium size dorsal root ganglia neurons (DRGN) the inositol-trisphosphate receptor (InsP3R) type 1 was often concentrated in the periphery of cells, which is in contrast to homogenous ER distribution. G protein-coupled designer receptors were used to further elucidate phosphoinositide mediated Ca2+ signaling: This approach showed strong InsP3 mediated Ca2+ signals close to the plasma membrane, which can be amplified by Ca2+ entry through TRPV4 channels. In addition, our results support a physical interaction and partial colocalization of InsP3R1 and TRPV4 channels. In the context of paclitaxel-induced neurotoxicity, blocking Ca2+ influx through TRPV4 channels reduced cell death in cultured DRGN. Pretreatment of mice with the pharmacological TRPV4 inhibitor HC067047 prior to paclitaxel injections prevented electrophysiological and behavioral changes associated with paclitaxel-induced neuropathy.In summary, these results underline the relevance of TRPV4 signaling for the pathogenesis of paclitaxel-induced neuropathy and suggest novel preventive strategies.

OATP1B2 deficiency protects against paclitaxel-induced neurotoxicity.

Paclitaxel is among the most widely used anticancer drugs and is known to cause a dose-limiting peripheral neurotoxicity, the initiating mechanisms of which remain unknown. Here, we identified the murine solute carrier organic anion-transporting polypeptide B2 (OATP1B2) as a mediator of paclitaxel-induced neurotoxicity. Additionally, using established tests to assess acute and chronic paclitaxel-induced neurotoxicity, we found that genetic or pharmacologic knockout of OATP1B2 protected mice from mechanically induced allodynia, thermal hyperalgesia, and changes in digital maximal action potential amplitudes. The function of this transport system was inhibited by the tyrosine kinase inhibitor nilotinib through a noncompetitive mechanism, without compromising the anticancer properties of paclitaxel. Collectively, our findings reveal a pathway that explains the fundamental basis of paclitaxel-induced neurotoxicity, with potential implications for its therapeutic management.

Partial Protection of Paclitaxel-induced Neurotoxicity by Antioxidants.

In order to search for substances that reduce the neurotoxicity of paclitaxel, the sensitivity of differentiated rat neuronal PC12 cells to paclitaxel was compared to that of malignant and non-malignant cells, and the extent to which four antioxidants can alleviate paclitaxel-induced neurotoxicity was investigated. Viability of cells was determined by the MTT method. Cytotoxicity was evaluated as the concentration that reduced cell viability by 50% (CC50). Tumor specificity of paclitaxel was determined as the ratio of CC50 against non-malignant cells to that against malignant cells. Paclitaxel was three-fold more cytotoxic towards human oral squamous cell carcinoma cell lines (Ca9-22, HSC-2, HSC-3. HSC-4) than human normal epithelial and mesenchymal (human gingival fibroblast, human periodontal ligament fibroblast, human pulp cell) normal cells, confirming its antitumor potential. However, paclitaxel at as low a concentration as 5 ng/ml significantly reduced neurite formation in nerve growth factor-induced differentiated PC12 cells, although complete killing of cells was not achieved even at 2,000-fold higher concentration (10 μM). Paclitaxel-induced neurotoxicity was enhanced with the prolongation of incubation time and reduction of inoculation cell density. Four antioxidants, namely docosahexaenoic acid, acetyl-L-carnitine hydrochloride, N-acetyl-L-cysteine and sodium ascorbate, only partially protected PC12 cells from paclitaxel-induced toxicity. The present study suggests the involvement of both oxidative and other mechanisms in paclitaxel-induced neurotoxicity.

Application of stem cell derived neuronal cells to evaluate neurotoxic chemotherapy

The generation of induced pluripotent stem cells (iPSCs) and differentiation to cells composing major organs has opened up the possibility for a new model system to study adverse toxicities associated with chemotherapy. Therefore, we used human iPSC-derived neurons to study peripheral neuropathy, one of the most common adverse effects of chemotherapy and cause for dose reduction. To determine the utility of these neurons in investigating the effects of neurotoxic chemotherapy, we measured morphological differences in neurite outgrowth, cell viability as determined by ATP levels and apoptosis through measures of caspase 3/7 activation following treatment with clinically relevant concentrations of platinating agents (cisplatin, oxaliplatin and carboplatin), taxanes (paclitaxel, docetaxel and nab-paclitaxel), a targeted proteasome inhibitor (bortezomib), an antiangiogenic compound (thalidomide), and 5-fluorouracil, a chemotherapeutic that does not cause neuropathy. We demonstrate differential sensitivity of neurons to mechanistically distinct classes of chemotherapeutics. We also show a dose-dependent reduction of electrical activity as measured by mean firing rate of the neurons following treatment with paclitaxel. We compared neurite outgrowth and cell viability of iPSC-derived cortical (iCell® Neurons) and peripheral (Peri.4U) neurons to cisplatin, paclitaxel and vincristine. Goshajinkigan, a Japanese herbal neuroprotectant medicine, was protective against paclitaxel-induced neurotoxicity but not oxaliplatin as measured by morphological phenotypes. Thus, we have demonstrated the utility of human iPSC-derived neurons as a useful model to distinguish drug class differences and for studies of a potential neuroprotectant for the prevention of chemotherapy-induced peripheral neuropathy.

Ethoxyquin provides neuroprotection against cisplatin-induced neurotoxicity

Ethoxyquin was recently identified as a neuroprotective compound against toxic neuropathies and efficacy was demonstrated against paclitaxel-induced neurotoxicity in vivo. In this study we examined the efficacy of ethoxyquin in preventing neurotoxicity of cisplatin in rodent models of chemotherapy-induced peripheral neuropathy and explored its mechanism of action. Ethoxyquin prevented neurotoxicity of cisplatin in vitro in a sensory neuronal cell line and primary rat dorsal root ganglion neurons. In vivo, chronic co-administration of ethoxyquin partially abrogated cisplatin-induced behavioral, electrophysiological and morphological abnormalities. Furthermore, ethoxyquin did not interfere with cisplatin’s ability to induce tumor cell death in ovarian cancer cell line in vitro and in vivo. Finally, ethoxyquin reduced the levels of two client proteins (SF3B2 and ataxin-2) of a chaperone protein, heat shock protein 90 (Hsp90) when co-administered with cisplatin in vitro. These results implied that the neuroprotective effect of ethoxyquin is mediated through these two client proteins of Hsp90. In fact, reducing levels of SF3B2 in tissue-cultured neurons was effective against neurotoxicity of cisplatin. These findings suggest that ethoxyquin or other compounds that inhibit chaperone activity of Hsp90 and reduce levels of its client protein, SF3B2 may be developed as an adjuvant therapy to prevent neurotoxicity in cisplatin-based chemotherapy protocols.

Insulin-like growth factor-1 attenuates apoptosis and protects neurochemical phenotypes of dorsal root ganglion neurons with paclitaxel-induced neurotoxicity in vitro

Paclitaxel (PT)-induced neurotoxicity is a significant problem associated with successful treatment of cancers. Insulin-like growth factor-1 (IGF-1) is a neurotrophic factor and plays an important role in promoting axonal growth from dorsal root ganglion (DRG) neurons. Whether IGF-1 has protective effects on neurite growth, cell viability, neuronal apoptosis and neuronal phenotypes in DRG neurons with PT-induced neurotoxicity is still unclear. In this study, primary cultured rat DRG neurons were used to assess the effects of IGF-1 on DRG neurons with PT-induced neurotoxicity. The results showed that PT exposure caused neurite retraction in a dose-dependent manner. PT exposure caused a decrease of cell viability and an increase in the ratio of apoptotic cells which could be reversed by IGF-1. The percentage of calcitonin gene-related peptide immunoreactive (CGRP-IR) neurons and neurofilament (NF)-200-IR neurons, mRNA, and protein levels of CGRP and NF-200 decreased significantly after treatment with PT. IGF-1 administration had protective effects on CGRP-IR neurons, but not on NF-200-IR neurons. Either extracellular signal-regulated protein kinase (ERK1/2) inhibitor PD98059 or phosphatidylinositol 3-kinase (PI3 K) inhibitor LY294002 blocked the effect of IGF-1. The results imply that IGF-1 may attenuate apoptosis to improve neuronal cell viability and promote neurite growth of DRG neurons with PT-induced neurotoxicity. Moreover, these results support an important neuroprotective role of exogenous IGF-1 on distinct subpopulations of DRG neurons which is responsible for skin sensation. The effects of IGF-1 might be through ERK1/2 or PI3 K/Akt signaling pathways. These findings provide experimental evidence for IGF-1 administration to alleviate neurotoxicity of distinct subpopulations of DRG neurons induced by PT.

Highlights of This Issue

This study engineered an existing antibody to discriminate between FGFR isoforms. While inhibiting FGFR2 or FGFR3 does not disrupt tissue homeostasis, blocking FGFR1 or FGFR4 carries a greater safety risk. R3Mab, an anti-FGFR3 antibody, was initially modified to bind tightly to FGFR3 and FGFR2 and moderately to FGFR4. Based on X-ray crystallographic data, it was further engineered to decrease FGFR4 binding affinity while retaining affinity for FGFR3 and FGFR2. The resulting dual-specific antibodies blocked FGF binding to FGFR3 and FGFR2 and displayed efficacy in mice against human tumor xenografts overexpressing FGFR3 or FGFR2. Thus, a monospecific antibody can be engineered to modify binding to closely related targets in order to expand and refine therapeutic potential.This study demonstrates that small cell lung cancer (SCLC) cells are exquisitely sensitive to growth inhibition by the BET inhibitor JQ1. JQ1 treatment has no impact on MYC protein expression, but results in downregulation of the lineage-specific transcription factor ASCL1. SCLC cells that are sensitive to JQ1 are also sensitive to ASCL1 depletion by RNA interference. Chromatin immunoprecipitation studies confirmed the binding of the BET protein BRD4 to the ASCL1 enhancer, and the ability of JQ1 to disrupt the interaction. The study provides a mechanistic basis for the sensitivity of SCLC to BET inhibition, and a rationale for the clinical development of BET inhibitors in this disease with high unmet medical need.This study aimed to discover potential neuroprotective drugs for paclitaxel-induced neurotoxicity. An image-based high-content platform was first developed to screen for potential neuroprotective drugs. In drug screening from compound libraries of ion channel ligands, REDOX and GABAergic ligands, 5-hydroxydecanoate (5-HD) exhibited the most significant neuroprotective effects against paclitaxel-induced neurotoxicity, both in cortical and dorsal root ganglion (DRG) neurons. In mouse behavioral tests, 5-HD restored the thermal sensitivity and alleviated mechanical allodynia induced by paclitaxel. The study establishes an imaged-based high-content screening platform and a protocol for verifying the neuroprotective effect in vivo, by which 5-HD was identified and validated as a potential neuroprotective drug for paclitaxel-induced neuropathy.Genetically engineered mouse models of lung cancer are important in understanding the function of novel lung cancer oncogenes and tumor suppressor genes identified in genomic studies of human lung cancer. Further, they are important platforms for preclinical therapeutic studies. This study generated a mouse model of lung adenocarcinoma driven by mutation of the discoidin domain receptor 2 (DDR2) gene combined with loss of TP53 and analyzed results to reach a conclusion that DDR2 mutation can drive lung cancer initiation in vivo and provide a novel mouse model for lung cancer therapeutics studies.

Integrating Image-Based High-Content Screening with Mouse Models Identifies 5-Hydroxydecanoate as a Neuroprotective Drug for Paclitaxel-Induced Neuropathy.

Chemotherapy-induced neurotoxicity is a common adverse effect of cancer treatment. No medication has been shown to be effective in the prevention or treatment of chemotherapy-induced neurotoxicity. This study aimed to discover potential neuroprotective drugs for paclitaxel-induced neurotoxicity. An image-based high-content platform was first developed to screen for potential neuroprotective drugs. The screening system comprised of automated image acquisition and multiparameter analysis, including neuronal viability, neurite outgrowth, and synaptogenesis. By this platform, we obtained a candidate list from compound libraries. In the drug screening from compound libraries of ion channel ligands, REDOX and GABAergic ligands, 5-hydroxydecanoate (5-HD) exhibited the most significant neuroprotective effects against paclitaxel-induced neurotoxicity in both cortical and dorsal root ganglion (DRG) neurons. In mouse behavioral tests, 5-HD restored the thermal sensitivity and alleviated mechanical allodynia induced by paclitaxel. Electron micrographs of sciatic nerve revealed that 5-HD reduced the damages caused by paclitaxel in the nonmyelinated and smaller myelinated fibers. The mechanistic study on DRG neurons suggested that 5-HD rescued the dysregulation of intracellular calcium homeostasis provoked by paclitaxel. Importantly, 5-HD did not jeopardize the antitumor effect of paclitaxel in tumor xenograft models. In conclusion, we established an imaged-based high-content screening platform and a protocol for verifying the neuroprotective effect in vivo, by which 5-HD was identified and validated as a potential neuroprotective drug for paclitaxel-induced neuropathy.