Evodiamine attenuates oxidative stress and ferroptosis by inhibiting the MAPK signaling to improve bortezomib-induced peripheral neurotoxicity.

BACKGROUND: Bortezomib (BTZ) is a commonly used antitumor drug, but its peripheral neuropathy side effect poses a limitation on its dosage. Evodiamine (EVO) exhibits various biological activities, including antioxidant, anti-inflammatory, and anticancer effects. The purpose of this investigation is to confirm the impact of EVO on BTZ-induced peripheral neurotoxicity. METHODS: GeneCards and HERB were applied to analyze the targets of peripheral neurotoxicity and EVO. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enrichment analysis of the hub genes were identified by DAVID. Rat dorsal root ganglion neurons (DRGs) and rat RSC96 Schwann cells (SCs) were treated with BTZ to simulate peripheral neurotoxicity. BTZ-induced peripheral neurotoxicity was assessed by detecting cell viability, proliferation, oxidative stress, and ferroptosis in DRGs and SCs. The mitogen-activated protein kinase (MAPK) signaling was scrutinized by Western blot assay. RESULTS: The Venn diagram for the overlapping targets of EVO and peripheral neurotoxicity showed that EVO might regulate peripheral neurotoxicity by influencing cell oxidative stress, ferroptosis, and MAPK signaling pathway. EVO attenuated BTZ-induced toxicity in DRGs and SCs. EVO attenuated BTZ-induced oxidative stress damage in DRGs and SCs by reducing reactive oxygen species and malondialdehyde levels and enhancing glutathione level. EVO attenuated BTZ-induced ferroptosis in DRGs and SCs. EVO inhibited BTZ-induced activation of the MAPK signaling in DRGs and SCs. Activation of the MAPK signaling reversed the neuroprotective effect of EVO on BTZ-induced oxidative stress injury and ferroptosis. CONCLUSION: EVO attenuated oxidative stress and ferroptosis by inhibiting the MAPK signaling to improve BTZ-induced peripheral neurotoxicity.

Bortezomib-Induced Ovarian Toxicity in Mice.

Cancer survivors may experience long-term adverse effects of cancer treatments such as premature ovarian failure and infertility. We aimed to investigate the potential effects and toxicity of bortezomib (BTZ) as an effective anticancer drug on ovaries, raise awareness to the negative consequences of the treatment, and help increase the quality of life after treatment. Mice were distributed into bortezomib (BTZ1, BTZ2) and saline-injected control groups (C1, C2) at a dose of 1 mg/kg twice per week for 6 weeks. We sacrificed C1, BTZ1 groups at day 1 and C2, BTZ2 groups at 4 weeks after the last injection. Ovary samples were examined using histopathological and immunohistochemical methods. Ovarian follicle impairment was detected on BTZ-treated mice and was associated with a statistically significant decreased population of primordial and antral follicles compared with control groups. In experimental groups, Caspase-3 and Ki67 expressions were increased, whereas estrogen receptor alpha (ERα) and progesterone receptor (PR) expressions were decreased in various developmental stages of follicles. BTZ specifically targets granulosa cells by inducing granulosa cell apoptosis and may have long-term effects on follicles. Bortezomib treatment may adversely affect ovarian function by accelerating ovarian reserve depletion and changing ERα and PR hormone levels that can cause fertility problems in the long term.

Investigation of the effects of berberine on bortezomib-induced sciatic nerve and spinal cord damage in rats through pathways involved in oxidative stress and neuro-inflammation.

Bortezomib (BTZ), a proteasome inhibitor, causes dose-limiting peripheral neuropathy in humans. Berberine (BBR), which has various biological and pharmacological properties, is known to have neuroprotective properties. The possible protective effects of BBR on peripheral neuropathy caused by BTZ were investigated in this study. For this purpose, BTZ was intraperitoneally given to Sprague dawley rats on the 1 st, 3rd, 5th, and 7th days with a cumulative dose of 0.8 mg/kg. Moreover, animals were orally administered 50 or 100 mg/kg BBR daily from day 1 to day 10. As a result of the analyzes performed on the sciatic nerve and spinal cord, it was observed that MDA levels and NRF-2, HO-1, NQO1, GCLC and GCLM mRNA transcript levels increased due to oxidative stress caused by BTZ, and the levels of these markers decreased after BBR administration. Also, it was determined that SOD, CAT, GPx and GSH levels increased after BBR treatment. It was observed that BTZ caused inflammation by triggering NF-κB, TNF-α, IL-1ß and IL-6 cytokines, on the other hand, with BBR treatment, these cytokines were suppressed and inflammation was alleviated. In addition, it was determined that the expressions of RAGE, STAT3, NLRP3 and TLR4, which have important roles in inflammation, increased with BTZ administration, but BBR suppressed the expressions of these genes. It was determined that the expressions of SIRT1, which plays an important role in neuropathic pain, and CREB-LI neurons, which has an active role in neurite outgrowth and survival, decreased with BTZ administration. It was observed that GFAP levels increased with BTZ administration and decreased with BBR administration. Given all the findings, it was concluded that BBR exhibits protective qualities in the sciatic nerve and spinal cord induced by BTZ.

Interplay between Prokineticins and Histone Demethylase KDM6A in a Murine Model of Bortezomib-Induced Neuropathy.

Chemotherapy-induced neuropathy (CIN) is a major adverse effect associated with many chemotherapeutics, including bortezomib (BTZ). Several mechanisms are involved in CIN, and recently a role has been proposed for prokineticins (PKs), a chemokine family that induces proinflammatory/pro-algogen mediator release and drives the epigenetic control of genes involved in cellular differentiation. The present study evaluated the relationships between epigenetic mechanisms and PKs in a mice model of BTZ-induced painful neuropathy. To this end, spinal cord alterations of histone demethylase KDM6A, nuclear receptors PPARα/PPARγ, PK2, and pro-inflammatory cytokines IL-6 and IL-1ß were assessed in neuropathic mice treated with the PK receptors (PKRs) antagonist PC1. BTZ treatment promoted a precocious upregulation of KDM6A, PPARs, and IL-6, and a delayed increase of PK2 and IL-1ß. PC1 counteracted allodynia and prevented the increase of PK2 and of IL-1ß in BTZ neuropathic mice. The blockade of PKRs signaling also opposed to KDM6A increase and induced an upregulation of PPAR gene transcription. These data showed the involvement of epigenetic modulatory enzymes in spinal tissue phenomena associated with BTZ painful neuropathy and underline a role of PKs in sustaining the increase of proinflammatory cytokines and in exerting an inhibitory control on the expression of PPARs through the regulation of KDM6A gene expression in the spinal cord.

Tubulin binding potentially clears up Bortezomib and Carfilzomib differential neurotoxic effect.

Proteasome inhibitors (PIs) represent the gold standard in the treatment of multiple myeloma. Among PIs, Bortezomib (BTZ) is frequently used as first line therapy, but peripheral neuropathy (PN), occurring approximately in 50% of patients, impairs their life, representing a dose-limiting toxicity. Carfilzomib (CFZ), a second-generation PI, induces a significantly less severe PN. We investigated possible BTZ and CFZ off-targets able to explain their different neurotoxicity profiles. In order to identify the possible PIs off-targets we used the SPILLO-PBSS software that performs a structure-based in silico screening on a proteome-wide scale. Among the top-ranked off-targets of BTZ identified by SPILLO-PBSS we focused on tubulin which, by contrast, did not turn out to be an off-target of CFZ. We tested the hypothesis that the direct interaction between BTZ and microtubules would inhibit the tubulin alfa GTPase activity, thus reducing the microtubule catastrophe and consequently furthering the microtubules polymerization. This hypothesis was validated in a cell-free model, since BTZ (but not CFZ) reduces the concentration of the free phosphate released during GTP hydrolysis. Moreover, NMR binding studies clearly demonstrated that BTZ, unlike CFZ, is able to interact with both tubulin dimers and polymerized form. Our data suggest that different BTZ and CFZ neurotoxicity profiles are independent from their proteasome inhibition, as demonstrated in adult mice dorsal root ganglia primary sensory neurons, and, first, we demonstrate, in a cell free model, that BTZ is able to directly bind and perturb microtubules.

Pilot Study: Quantitative Photoacoustic Evaluation of Peripheral Vascular Dynamics Induced by Carfilzomib In Vivo.

Carfilzomib is mainly used to treat multiple myeloma. Several side effects have been reported in patients treated with carfilzomib, especially those associated with cardiovascular events, such as hypertension, congestive heart failure, and coronary artery disease. However, the side effects, especially the manifestation of cardiovascular events through capillaries, have not been fully investigated. Here, we performed a pilot experiment to monitor peripheral vascular dynamics in a mouse ear under the effects of carfilzomib using a quantitative photoacoustic vascular evaluation method. Before and after injecting the carfilzomib, bortezomib, and PBS solutions, we acquired high-resolution three-dimensional PAM data of the peripheral vasculature of the mouse ear during each experiment for 10 h. Then, the PAM maximum amplitude projection (MAP) images and five quantitative vascular parameters, i.e., photoacoustic (PA) signal, diameter, density, length fraction, and fractal dimension, were estimated. Quantitative results showed that carfilzomib induces a strong effect on the peripheral vascular system through a significant increase in all vascular parameters up to 50%, especially during the first 30 min after injection. Meanwhile, bortezomib and PBS do not have much impact on the peripheral vascular system. This pilot study verified PAM as a comprehensive method to investigate peripheral vasculature, along with the effects of carfilzomib. Therefore, we expect that PAM may be useful to predict cardiovascular events caused by carfilzomib.

Prokineticin Receptor Inhibition With PC1 Protects Mouse Primary Sensory Neurons From Neurotoxic Effects of Chemotherapeutic Drugs in vitro.

Neurotoxicity is a common side effect of chemotherapeutics that often leads to the development of chemotherapy-induced peripheral neuropathy (CIPN). The peptide Prokineticin 2 (PK2) has a key role in experimental models of CIPN and can be considered an insult-inducible endangering mediator. Since primary afferent sensory neurons are highly sensitive to anticancer drugs, giving rise to dysesthesias, the aim of our study was to evaluate the alterations induced by vincristine (VCR) and bortezomib (BTZ) exposure in sensory neuron cultures and the possible preventive effect of blocking PK2 signaling. Both VCR and BTZ induced a concentration-dependent reduction of total neurite length that was prevented by the PK receptor antagonist PC1. Antagonizing the PK system also reduced the upregulation of PK2, PK-R1, TLR4, IL-6, and IL-10 expression induced by chemotherapeutic drugs. In conclusion, inhibition of PK signaling with PC1 prevented the neurotoxic effects of chemotherapeutics, suggesting a promising strategy for neuroprotective therapies against the sensory neuron damage induced by exposure to these drugs.

Mitochondrial Functions, Energy Metabolism and Protein Glycosylation are Interconnected Processes Mediating Resistance to Bortezomib in Multiple Myeloma Cells.

The proteasome inhibitor bortezomib (BTZ) has emerged as an effective drug for the treatment of multiple myeloma even though many patients relapse from BTZ therapy. The present study investigated the metabolic pathways underlying the acquisition of bortezomib resistance in multiple myeloma. We used two different clones of multiple myeloma cell lines exhibiting different sensitivities to BTZ (U266 and U266-R) and compared them in terms of metabolic profile, mitochondrial fitness and redox balance homeostasis capacity. Our results showed that the BTZ-resistant clone (U266-R) presented increased glycosylated UDP-derivatives when compared to BTZ-sensitive cells (U266), thus also suggesting higher activities of the hexosamine biosynthetic pathway (HBP), regulating not only protein O- and N-glycosylation but also mitochondrial functions. Notably, U266-R displayed increased mitochondrial biogenesis and mitochondrial dynamics associated with stronger antioxidant defenses. Furthermore, U266-R maintained a significantly higher concentration of substrates for protein glycosylation when compared to U266, particularly for UDP-GlcNac, thus further suggesting the importance of glycosylation in the BTZ pharmacological response. Moreover, BTZ-treated U266-R showed significantly higher ATP/ADP ratios and levels of ECP and also exhibited increased mitochondrial fitness and antioxidant response. In conclusions, our findings suggest that the HBP may play a major role in mitochondrial fitness, driving BTZ resistance in multiple myeloma and thus representing a possible target for new drug development for BTZ-resistant patients.

Higher proteotoxic stress rather than mitochondrial damage is involved in higher neurotoxicity of bortezomib compared to carfilzomib.

Proteasome inhibitors have great success for their therapeutic potential against hematologic malignancies. First generation proteasome inhibitor bortezomib induced peripheral neuropathy is considered as a limiting factor in chemotherapy and its second-generation counterpart carfilzomib is associated with lower rates of neurotoxicity. The mitochondrial toxicity (mitotoxicity) hypothesis arises from studies with animal models of bortezomib induced peripheral neuropathy. However, molecular mechanisms are not fully elucidated and the role of mitotoxicity in bortezomib and carfilzomib induced neurotoxicity has not been investigated comparatively. Herein, we characterized the neurotoxic effects of bortezomib and carfilzomib at the molecular level in human neuronal cells using LC-MS/MS analysis, flow cytometry, RT-qPCR, confocal microscopy and western blotting. We showed that bortezomib and carfilzomib affected the human neuronal proteome differently, and bortezomib caused higher proteotoxic stress via protein oxidation, protein K48-ubiquitination, heat shock protein expression upregulation and reduction of mitochondria membrane potential. Bortezomib and carfilzomib did not affect the gene expression levels related to mitochondrial dynamics (optic atrophy 1; OPA1, mitofusin 1; MFN1, mitofusin 2; MFN2, fission 1; FIS1, dynamin-related protein 1; DRP1) and overall mitophagy rate whereas, PINK1/Parkin mediated mitophagy gene expressions were altered with both drugs. Bortezomib and carfilzomib caused downregulation of the contents of mitochondrial oxidative phosphorylation complexes, voltage-dependent anion channel 1 (VDAC1) and uncoupling protein 2 (UCP2) similarly. Our findings suggest that, both drugs induce mitotoxicity besides proteotoxic stress in human neuronal cells and the higher incidence of neurotoxicity with bortezomib than carfilzomib is not directly related to mitochondrial pathways.

Optimization of cell viability assays to improve replicability and reproducibility of cancer drug sensitivity screens.

Cancer drug development has been riddled with high attrition rates, in part, due to poor reproducibility of preclinical models for drug discovery. Poor experimental design and lack of scientific transparency may cause experimental biases that in turn affect data quality, robustness and reproducibility. Here, we pinpoint sources of experimental variability in conventional 2D cell-based cancer drug screens to determine the effect of confounders on cell viability for MCF7 and HCC38 breast cancer cell lines treated with platinum agents (cisplatin and carboplatin) and a proteasome inhibitor (bortezomib). Variance component analysis demonstrated that variations in cell viability were primarily associated with the choice of pharmaceutical drug and cell line, and less likely to be due to the type of growth medium or assay incubation time. Furthermore, careful consideration should be given to different methods of storing diluted pharmaceutical drugs and use of DMSO controls due to the potential risk of evaporation and the subsequent effect on dose-response curves. Optimization of experimental parameters not only improved data quality substantially but also resulted in reproducible results for bortezomib- and cisplatin-treated HCC38, MCF7, MCF-10A, and MDA-MB-436 cells. Taken together, these findings indicate that replicability (the same analyst re-performs the same experiment multiple times) and reproducibility (different analysts perform the same experiment using different experimental conditions) for cell-based drug screens can be improved by identifying potential confounders and subsequent optimization of experimental parameters for each cell line.

(1 → 3)-ß-d-glucan enhances the toxicity induced by Bortezomib in rat testis.

We aimed to determine the possible effects of the antioxidant agent (1 â†’ 3)-ß-D-glucan on bortezomib-induced rat testis damage. We used five groups of rats; control, (1 â†’ 3)-ß-D-glucan (75 mg/kg), bortezomib group, bortezomib + (1 â†’ 3)-ß-D-glucan groups (injection of (1 â†’ 3)-ß-D-glucan after bortezomib and sacrificed at 48th or 72nd h). The effects of these substances were assessed by measuring the levels of the antioxidant enzymes and LPO, and by performing immunohistochemical analysis with NF-κB. The histology of testis was evaluated using aniline blue staining. (1 â†’ 3)-ß-D-glucan leads to significant reductions in the levels of antioxidant enzymes and increased levels of LPO in testes. Moreover, it increased the NF-κB immunopositivity significantly in testis, especially in Bortezomib + (1 â†’ 3)-ß-D-glucan group at 48th h. The histological changes were observed in the bortezomib and/or (1 â†’ 3)-ß-D-glucan groups. Our results demonstrated that testis damage caused by the treatment with bortezomib was not eliminated by (1 â†’ 3)-ß-D-glucan and shockingly it increased the damage. PRACTICAL APPLICATIONS: The testis damage caused by the treatment with bortezomib was not eliminated by (1 â†’ 3)-ß-D-glucan and as a result, ß-1,3-(D)-glucan enhanced the toxicity by leading a decrease in the levels of GSH, SOD, and CAT, thus caused an elevation in the immunoreactivity of NF-κB and altered the histopathological changes by enhancing the toxic effects of bortezomib. The findings of the previous studies about the antioxidative activity of (1 â†’ 3)-ß-D-glucan are controversial. So, it is necessary to consider the cytotoxicity of (1 â†’ 3)-ß-D-glucan in testis tissue. Thus, more studies on testis tissue are necessary to confirm that (1 â†’ 3)-ß-D-glucan is safe as an antioxidant.

Bortezomib induces HSV-1 lethality in mice with neutrophil deficiency.

Bortezomib suppressing NF-κB activity is an effective therapy for patients with myeloma or lymphoma. However, this drug can cause adverse effects, neutropenia, and recurrent infections of herpes viruses. Among herpes viruses, HSV-1 can reactivate to induce mortality. The important issues regarding how bortezomib diminishes neutrophils, whether bortezomib can induce HSV-1 reactivation, and how bortezomib exacerbates HSV-1 infection, need investigation. Using the murine model, we found that bortezomib induced HSV-1 reactivation. Bortezomib diminished neutrophil numbers in organs of uninfected and HSV-1-infected mice and turned a nonlethal infection to lethal with elevated tissue viral loads. In vitro results showed that bortezomib and HSV-1 collaborated to enhance the death and apoptosis of mouse neutrophils. The leukocyte deficiency induced by chemotherapies is generally believed to be the cause for aggravating virus infections. Here we show the potential of pathogen to exacerbate chemotherapy-induced leukocyte deficiency.

Non-lethal proteasome inhibition activates pro-tumorigenic pathways in multiple myeloma cells.

Multiple myeloma (MM) is a haematological malignancy being characterized by clonal plasma cell proliferation in the bone marrow. Targeting the proteasome with specific inhibitors (PIs) has been proven a promising therapeutic strategy and PIs have been approved for the treatment of MM and mantle-cell lymphoma; yet, while outcome has improved, most patients inevitably relapse. As relapse refers to MM cells that survive therapy, we sought to identify the molecular responses induced in MM cells after non-lethal proteasome inhibition. By using bortezomib (BTZ), epoxomicin (EPOX; a carfilzomib-like PI) and three PIs, namely Rub999, PR671A and Rub1024 that target each of the three proteasome peptidases, we found that only BTZ and EPOX are toxic in MM cells at low concentrations. Phosphoproteomic profiling after treatment of MM cells with non-lethal (IC10 ) doses of the PIs revealed inhibitor- and cell type-specific readouts, being marked by the activation of tumorigenic STAT3 and STAT6. Consistently, cytokine/chemokine profiling revealed the increased secretion of immunosuppressive pro-tumorigenic cytokines (IL6 and IL8), along with the inhibition of potent T cell chemoattractant chemokines (CXCL10). These findings indicate that MM cells that survive treatment with therapeutic PIs shape a pro-tumorigenic immunosuppressive cellular and secretory bone marrow microenvironment that enables malignancy to relapse.

In vitro and in vivo investigation of cardiotoxicity associated with anticancer proteasome inhibitors and their combination with anthracycline.

Although proteasome inhibitors (PIs) are modern targeted anticancer drugs, they have been associated with a certain risk of cardiotoxicity and heart failure (HF). Recently, PIs have been combined with anthracyclines (ANTs) to further boost their anticancer efficacy. However, this raised concerns regarding cardiac safety, which were further supported by several in vitro studies on immature cardiomyocytes. In the present study, we investigated the toxicity of clinically used PIs alone (bortezomib (BTZ), carfilzomib (CFZ)) as well as their combinations with an ANT (daunorubicin (DAU)) in both neonatal and adult ventricular cardiomyocytes (NVCMs and AVCMs) and in a chronic rabbit model of DAU-induced HF. Using NVCMs, we found significant cytotoxicity of both PIs around their maximum plasma concentration (cmax) as well as significant augmentation of DAU cytotoxicity. In AVCMs, BTZ did not induce significant cytotoxicity in therapeutic concentrations, whereas the toxicity of CFZ was significant and more profound. Importantly, neither PI significantly augmented the cardiotoxicity of DAU despite even more profound proteasome-inhibitory activity in AVCMs compared with NVCMs. Furthermore, in young adult rabbits, no significant augmentation of chronic ANT cardiotoxicity was noted with respect to any functional, morphological, biochemical or molecular parameter under study, despite significant inhibition of myocardial proteasome activity. Our experimental data show that combination of PIs with ANTs is not accompanied by an exaggerated risk of cardiotoxicity and HF in young adult animal cardiomyocytes and hearts.

Targeting prokineticin system counteracts hypersensitivity, neuroinflammation, and tissue damage in a mouse model of bortezomib-induced peripheral neuropathy.

BACKGROUND: Neuropathy is a dose-limiting side effect of many chemotherapeutics, including bortezomib. The mechanisms underlying this condition are not fully elucidated even if a contribution of neuroinflammation was suggested. Here, we investigated the role of a chemokine family, the prokineticins (PKs), in the development of bortezomib-induced peripheral neuropathy (BIPN), and we used a PK receptor antagonist to counteract the development and progression of the pathology. METHODS: Neuropathy was induced in male C57BL/6J mice by using a protocol capable to induce a detectable neuropathic phenotype limiting systemic side effects. The presence of allodynia (both mechanical and thermal) and thermal hyperalgesia was monitored over time. Mice were sacrificed at two different time points: 14 and 28 days after the first bortezomib (BTZ) injection. At these times, PK system activation (PK2 and PK-Rs), macrophage and glial activation markers, and cytokine production were evaluated in the main station involved in pain transmission (sciatic nerve, DRG, and spinal cord), and the effect of a PK receptors antagonist (PC1) on the same behavioral and biochemical parameters was assessed. Structural damage of DRG during BTZ treatment and an eventual protective effect of PC1 were also evaluated. RESULTS: BTZ induces in mice a dose-related allodynia and hyperalgesia and a progressive structural damage to the DRG. We observed a precocious increase of macrophage activation markers and unbalance of pro- and anti-inflammatory cytokines in sciatic nerve and DRG together with an upregulation of GFAP in the spinal cord. At higher BTZ cumulative dose PK2 and PK receptors are upregulated in the PNS and in the spinal cord. The therapeutic treatment with the PK-R antagonist PC1 counteracts the development of allodynia and hyperalgesia, ameliorates the structural damage in the PNS, decreases the levels of activated macrophage markers, and prevents full neuroimmune activation in the spinal cord. CONCLUSIONS: PK system may be a strategical pharmacological target to counteract BTZ-induced peripheral neuropathy. Blocking PK2 activity reduces progressive BTZ toxicity in the DRG, reducing neuroinflammation and structural damage to DRG, and it may prevent spinal cord sensitization.

Critical role of Cav3.2 T-type calcium channels in the peripheral neuropathy induced by bortezomib, a proteasome-inhibiting chemotherapeutic agent, in mice.

Bortezomib, a first-line agent for treatment of multiple myeloma, exhibits anticancer activity through proteasome inhibition. However, bortezomib-induced peripheral neuropathy (BIPN) is one of the most serious side effects. Since decreased proteasomal degradation of Cav3.2 T-type calcium channels in the primary afferents is involved in persistent pain, we investigated whether BIPN involves increased protein levels of Cav3.2 in mice. Six repeated i.p. administrations of bortezomib for 12 days developed persistent mechanical allodynia. Systemic administration of novel T-type calcium channel blockers, (2R/S)-6-prenylnaringenin and KTt-45, and of TTA-A2, the well-known blocker, reversed the BIPN. Ascorbic acid, known to block Cav3.2, but not Cav3.1 or 3.3, and silencing of Cav3.2 gene also suppressed BIPN. Protein levels of Cav3.2 in the dorsal root ganglion (DRG) at L4-L6 levels increased throughout days 1-21 after the onset of bortezomib treatment. Protein levels of USP5, a deubiquitinating enzyme that specifically inhibits proteasomal degradation of Cav3.2, increased in DRG on days 3-21, but not day 1, in bortezomib-treated mice. In DRG-derived ND7/23 cells, bortezomib increased protein levels of Cav3.2 and T-channel-dependent currents, as assessed by a patch-clamp method, but did not upregulate expression of Cav3.2 mRNA or USP5 protein. MG-132, another proteasome inhibitor, also increased Cav3.2 protein levels in the cultured cells. Given the previous evidence for USP5 induction following nociceptor excitation, our data suggest that BIPN involves the increased protein levels of Cav3.2 in nociceptors through inhibition of proteasomal degradation of Cav3.2 by bortezomib itself and then by USP5 that is upregulated probably in an activity-dependent manner.

Proteomic approach for understanding milder neurotoxicity of Carfilzomib against Bortezomib.

The proteasomal system is responsible for the turnover of damaged proteins. Because of its important functions in oncogenesis, inhibiting the proteasomal system is a promising therapeutic approach for cancer treatment. Bortezomib (BTZ) is the first proteasome inhibitor approved by FDA for clinical applications. However neuropathic side effects are dose limiting for BTZ as many other chemotherapeutic agents. Therefore second-generation proteasome inhibitors have been developed including carfilzomib (CFZ). Aim of the present work was investigating the mechanisms of peripheral neuropathy triggered by the proteasome inhibitor BTZ and comparing the pathways affected by BTZ and CFZ, respectively. Neural stem cells, isolated from the cortex of E14 mouse embryos, were treated with BTZ and CFZ and mass spectrometry was used to compare the global protein pool of treated cells. BTZ was shown to cause more severe cytoskeletal damage, which is crucial in neural cell integrity. Excessive protein carbonylation and actin filament destabilization were also detected following BTZ treatment that was lower following CFZ treatment. Our data on cytoskeletal proteins, chaperone system, and protein oxidation may explain the milder neurotoxic effects of CFZ in clinical applications.

Tamoxifen suppresses paclitaxel-, vincristine-, and bortezomib-induced neuropathy via inhibition of the protein kinase C/extracellular signal-regulated kinase pathway.

Chemotherapy-induced neuropathy is a highly problematic, dose-limiting effect of potentially curative regimens of cancer chemotherapy. When neuropathic pain is severe, patients often either switch to less-effective chemotherapy agents or choose to discontinue chemotherapy entirely. Conventional chemotherapy drugs used to treat lung and breast cancer, multiple myeloma, and lymphoma include paclitaxel, vincristine, and bortezomib. Approximately 68% of patients receiving these anticancer drugs develop neuropathy within the first month of treatment, and while strategies to prevent chemotherapy-induced neuropathy have been investigated, none have yet been proven as effective. Recent reports suggest that chemotherapy-induced neuropathy is associated with signal transduction molecules, including protein kinase C and mitogen-activated protein kinases. It is currently unclear whether protein kinase C inhibition can prevent chemotherapy-induced neuropathy. In this study, we found that tamoxifen, a protein kinase C inhibitor, suppressed paclitaxel-, vincristine-, and bortezomib-induced cold and mechanical allodynia in mice. In addition, chemotherapy drugs induce neuropathy via the protein kinase C/extracellular signal-regulated kinase pathway in the spinal cord in lumbar segments 4-6 and dorsal root ganglions. In addition, tamoxifen was shown to act synergistically with paclitaxel to inhibit tumor-growth in mice injected with tumor cells. Our results indicated that paclitaxel-, vincristine-, and bortezomib-induced neuropathies were associated with the protein kinase C/extracellular signal-regulated kinase pathway in the lumbar spinal cord and dorsal root ganglions, which suggest that protein kinase C inhibitors may be therapeutically effective for the prevention of chemotherapy-induced neuropathy when administered with standard chemotherapy agents.

Reduction of SIRT1 epigenetically upregulates NALP1 expression and contributes to neuropathic pain induced by chemotherapeutic drug bortezomib.

BACKGROUND: Bortezomib is a frequently used chemotherapeutic drug for the treatment of multiple myeloma and other nonsolid malignancies. Accumulating evidence has demonstrated that bortezomib-induced persistent pain serves as the most frequent reason for treatment discontinuation. METHODS: The von Frey test was performed to evaluate neuropathic pain behavior, and real-time quantitative reverse transcription polymerase chain reaction, chromatin immunoprecipitation, western blot, immunohistochemistry, and small interfering RNA were performed to explore the molecular mechanisms in adult male Sprague-Dawley rats. RESULTS: We found that application of bortezomib significantly increased the expression of NALP1 protein and mRNA levels in spinal dorsal horn neurons, and intrathecal application of NALP1 siRNA attenuated the bortezomib-induced mechanical allodynia. In addition, bortezomib also decreased the SIRT1 expression, and treatment with SIRT1 activator resveratrol ameliorated the NALP1 upregulation and mechanical allodynia induced by bortezomib. Meanwhile, knockdown of SIRT1 using the SIRT1 siRNA induced the NALP1 upregulation in dorsal horn and mechanical allodynia in normal animal. These results suggested that reduction of SIRT1 induced the NALP1 upregulation in dorsal horn neurons, and participated in bortezomib-induced mechanical allodynia. Importantly, we found that the binding of SIRT1 and NALP1 promoter region did not change before and after bortezomib treatment, but SIRT1 downregulation increased p-STAT3 expression. Furthermore, the activation of STAT3 enhanced the recruitment of p-STAT3 to the Nalp1 gene promoter, which increased the acetylation of histone H3 and H4 in NALP1 promoter regions and epigenetically upregulated NALP1 expression in the rodents with bortezomib treatment. CONCLUSION: These findings suggested a new epigenetic mechanism for NALP1 upregulation involving SIRT1 reduction and subsequent STAT3-mediated histone hyperacetylation in NALP1 promoter region in dorsal horn neurons, which contributed to the bortezomib-induced mechanical allodynia.

High-dose intravenous immunoglobulins reduce nerve macrophage infiltration and the severity of bortezomib-induced peripheral neurotoxicity in rats.

BACKGROUND: Chemotherapy-induced peripheral neurotoxicity (CIPN) is a severe adverse effect in patients receiving antitumor agents, and no effective treatment is available. Although the mechanisms responsible for the development of CIPN are poorly understood, recent findings make neuroinflammation an attractive target to be investigated, particularly when neuropathic pain is a prominent feature such as after bortezomib administration. The aim of our study was to evaluate the effect of intravenous immunoglobulins (IVIg) delivery in chronic CIPN. The related neuro-immune aspects were investigated in a well-characterized rat model of bortezomib-induced peripheral neurotoxicity (BIPN). METHODS: After determination of a suitable schedule based on a preliminary pharmacokinetic pilot study, female Wistar rats were treated with IVIg 1 g/kg every 2 weeks. IVIg treatment was started at the beginning of bortezomib administration ("preventive" schedule), or once BIPN was already ensued after 4 weeks of treatment ("therapeutic" schedule). Neurophysiological and behavioral studies were performed to assess the extent of painful peripheral neurotoxicity induced by bortezomib, and these functional assessments were completed by pathologic examination of peripheral nerves and intraepidermal nerve fiber quantification (IENF). The role of the innate immune response in BIPN was investigated by immunochemistry characterization of macrophage infiltration in peripheral nerves. RESULTS: Both schedules of IVIg administration were able to significantly reduce bortezomib-induced heat and mechanical allodynia. Although these changes were not evidenced at the neurophysiological examination of peripheral nerves, they behavioral effects were paralleled in the animals treated with the preventive schedule by reduced axonopathy in peripheral nerves and significant protection from loss of IENF. Moreover, IVIg administration was very effective in reducing infiltration in peripheral nerves of macrophages with the M1, pro-inflammatory phenotype. CONCLUSION: Our results suggest a prominent role of neuroinflammation in BIPN and that IVIg might be considered as a possible safe and effective therapeutic option preventing M1 macrophage infiltration. However, since neuropathic pain is frequent also in other CIPN types, it also indicates the need for further investigation in other forms of CIPN.