BGP-15, a hydroximic acid derivative, protects against cisplatin- or taxol-induced peripheral neuropathy in rats

Potential small effector molecules restoring cellular defects due to sialic acid biosynthetic enzyme deficiency: Pathological relevance to GNE myopathy

GNEM (GNE Myopathy) is a rare neuromuscular disease caused due to biallelic mutations in sialic acid biosynthetic GNE enzyme (UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine Kinase). Recently direct or indirect role of GNE in other cellular functions have been elucidated. Hyposialylation of IGF-1R leads to apoptosis due to mitochondrial dysfunction while hyposialylation of β1 integrin receptor leads to altered F-actin assembly, disrupted cytoskeletal organization and slow cell migration. Other cellular defects in presence of GNE mutation include altered ER redox state and chaperone expression such as HSP70 or PrdxIV. Currently, there is no cure to treat GNEM. Possible therapeutic trials focus on supplementation with sialic acid, ManNAc, sialyllactose and gene therapy that slows the disease progression. In the present study, we analyzed the effect of small molecules like BGP-15 (HSP70 modulator), IGF-1 (IGF-1R ligand) and CGA (cofilin activator) on cellular phenotypes of GNE heterozygous knock out L6 rat skeletal muscle cell line (SKM‑GNEHz). Treatment with BGP-15 improved GNE epimerase activity by 40 % and reduced ER stress by 45 % for SKM‑GNEHz. Treatment with IGF-1 improved epimerase activity by 37.5 %, F-actin assembly by 100 %, cell migration upto 36 % (36 h) and atrophy by 0.44-fold for SKM‑GNEHz. Treatment with CGA recovered epimerase activity by 49 %, F-actin assembly by 132 % and cell migration upto 41 % (24 h) in SKM‑GNEHz. Our study shows that treatment with these small effector molecules reduces the detrimental phenotype observed in SKM‑GNEHz, thereby, providing insights into potential therapeutic targets for GNEM.

BGP-15 alleviates LPS-induced depression-like behavior by promoting mitophagy

The high prevalence of major depressive disorder (MDD) frequently imposes severe constraints on psychosocial functioning and detrimentally impacts overall well-being. Despite the growing interest in the hypothesis of mitochondrial dysfunction, the precise mechanistic underpinnings and therapeutic strategies remain unclear and require further investigation. In this study, an MDD model was established in mice using lipopolysaccharide (LPS). Our research findings demonstrated that LPS exposure induced depressive-like behaviors and disrupted mitophagy by diminishing the mitochondrial levels of PINK1/Parkin in the brains of mice. Furthermore, LPS exposure evoked the activation of the NLRP3 inflammasome, accompanied by a notable elevation in the concentrations of pro-inflammatory factors (TNF-α, IL-1β, and IL-6). Additionally, neuronal apoptosis was stimulated through the JNK/p38 pathway. The administration of BGP-15 effectively nullified the impact of LPS, corresponding to the amelioration of depressive-like phenotypes and restoration of mitophagy, prevention of neuronal injury and inflammation, and suppression of reactive oxygen species (ROS)-mediated NLRP3 inflammasome activation. Furthermore, we elucidated the involvement of mitophagy in BGP-15-attenuated depressive-like behaviors using the inhibitors targeting autophagy (3-MA) and mitophagy (Mdivi-1). Notably, these inhibitors notably counteracted the antidepressant and anti-inflammatory effects exerted by BGP-15. Based on the research findings, it can be inferred that the antidepressant properties of BGP-15 in LPS-induced depressive-like behaviors could potentially be attributed to the involvement of the mitophagy pathway. These findings offer a potential novel therapeutic strategy for managing MDD.

Complicated Role of Post-translational Modification and Protease-Cleaved Fragments of Tau in Alzheimer's Disease and Other Tauopathies

Tau, a microtubule-associated protein predominantly localized in neuronal axons, plays a crucial role in promoting microtubule assembly, stabilizing their structure, and participating in axonal transport. Perturbations in tau's structure and function are implicated in the pathogenesis of neurodegenerative diseases collectively known as tauopathies, the most common disorder of which is Alzheimer's disease (AD). In tauopathies, it has been found that tau has a variety of post-translational modification (PTM) abnormalities and/or tau is cleaved into a variety of fragments by some specific proteolytic enzymes; however, the precise contributions of these abnormal modifications and fragments to disease onset and progression remain incompletely understood. Herein, we provide an overview about the involvement of distinctive abnormal tau PTMs and different tau fragments in the pathogenesis of AD and other tauopathies and discuss the involvement of proteolytic enzymes such as caspases, calpains, and asparagine endopeptidase in mediating tau cleavage while also addressing the intercellular transmission role played by tau. We anticipate that further exploration into PTMs and fragmented forms of tau will yield valuable insights for diagnostic approaches and therapeutic interventions targeting AD and other related disorders.

Acetylated tau exacerbates learning and memory impairment by disturbing with mitochondrial homeostasis

Increased tau acetylation at K274 and K281 has been observed in the brains of Alzheimer's disease (AD) patients and animal models, and mitochondrial dysfunction are noticeable and early features of AD. However, the effect of acetylated tau on mitochondria has been unclear until now. Here, we constructed three type of tau forms, acetylated tau mutant by mutating its K274/K281 into Glutamine (TauKQ) to mimic disease-associated lysine acetylation, the non-acetylation tau mutant by mutating its K274/K281 into Arginine (TauKR) and the wild-type human full-length tau (TauWT). By overexpression of these tau forms in vivo and in vitro, we found that, TauKQ induced more severe cognitive deficits with neuronal loss, dendritic plasticity damage and mitochondrial dysfunctions than TauWT. Unlike TauWT induced mitochondria fusion, TauKQ not only induced mitochondria fission by decreasing mitofusion proteins, but also inhibited mitochondrial biogenesis via reduction of PGC-1a/Nrf1/Tfam levels. TauKR had no significant difference in the cognitive and mitochondrial abnormalities compared with TauWT. Treatment with BGP-15 rescued impaired learning and memory by attenuation of mitochondrial dysfunction, neuronal loss and dendritic complexity damage, which caused by TauKQ. Our data suggested that, acetylation at K274/281 was an important post translational modification site for tau neurotoxicity, and BGP-15 is a potential therapeutic drug for AD.

Nicotinic Amidoxime Derivate BGP-15, Topical Dosage Formulation and Anti-Inflammatory Effect

BGP-15 is a Hungarian-developed drug candidate with numerous beneficial effects. Its potential anti-inflammatory effect is a common assumption, but it has not been investigated in topical formulations yet. The aim of our study was to formulate 10% BGP-15 creams with different penetration enhancers to ensure good drug delivery, improve bioavailability of the drug and investigate the potential anti-inflammatory effect of BGP-15 creams in vivo. Since the exact mechanism of the effect is still unknown, the antioxidant effect (tested with UVB radiation) and the ability of BGP-15 to decrease macrophage activation were evaluated. Biocompatibility investigations were carried out on HaCaT cells to make sure that the formulations and the selected excipients can be safely used. Dosage form studies were also completed with texture analysis and in vitro release with Franz diffusion chamber apparatus. Our results show that the ointments were able to reduce the extent of local inflammation in mice, but the exact mechanism of the effect remains unknown since BGP-15 did not show any antioxidant effect, nor was it able to decrease LPS-induced macrophage activation. Our results support the hypothesis that BGP-15 has a potential anti-inflammatory effect, even if it is topically applied, but the mechanism of the effect remains unclear and requires further pharmacological studies.

Improved Survival and Retinal Function of Aging ZDF Rats in Long-Term, Uncontrolled Diabetes by BGP-15 Treatment

Retinal complications of diabetes often lead to deterioration or even loss of vision. This hastens discovery of pharmacological agents able to counterbalance diabetic retinopathy. BGP-15, an emerging small molecule agent, was formerly proven by our workgroup to be retinoprotective on nonobese diabetic animals, Goto-Kakizaki rats. In the present study, we aimed to examine its long-term tolerability or incidental side effects on obese-prone Zucker diabetic fatty (ZDF) rats to further increase the rationale for a future human translation. To make terminal visual status comparable with our other investigations, we also carried out electroretinography (ERG) at the end of the experiment. Our study was started on 16-week-old ZDF rats and lasted for 52 weeks, while BGP was administered daily by gavage. During the 12 months of treatment, 100% of BGP-treated animals survived compared to the non-treated ZDF group, where 60% of the animals died, which was a statistically significant difference. Based on ERG results, BGP-15 was able to counterbalance visual deterioration of ZDF rats caused by long-term diabetes. Some moderate but significant changes were seen in OGTT results and some relationship to oxidative stress by the western blot method: BGP-15 was able to increase expression of HSP70 and decrease that of NFkB in eyes of rats. These were in concert with our previous observations of SIRT1 increment and MMP9 decrement in diabetic eyes by BGP. In summary, not only is BGP-15 not harmful in the long run but it is even able to reduce the related mortality and the serious consequences of diabetes. BGP-15 is an excellent candidate for future drug development against diabetic retinopathy.

Myocardial ischaemia reperfusion injury and cardioprotection in the presence of sensory neuropathy: Therapeutic options

During the last decades, mortality from acute myocardial infarction has been dramatically reduced. However, the incidence of post‐infarction heart failure is still increasing. Cardioprotection by ischaemic conditioning had been discovered more than three decades ago. Its clinical translation, however, is still an unmet need. This is mainly due to the disrupted cardioprotective signalling pathways in the presence of different cardiovascular risk factors, co‐morbidities and the medication being taken. Sensory neuropathy is one of the co‐morbidities that has been shown to interfere with cardioprotection. In the present review, we summarize the diverse aetiology of sensory neuropathies and the mechanisms by which these neuropathies may interfere with ischaemic heart disease and cardioprotective signalling. Finally, we suggest future therapeutic options targeting both ischaemic heart and sensory neuropathy simultaneously.

LINKED ARTICLES

This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.23/issuetoc

Retinoprotection by BGP-15, a Hydroximic Acid Derivative, in a Type II Diabetic Rat Model Compared to Glibenclamide, Metformin, and Pioglitazone

High blood glucose and the consequential ischemia-reperfusion (I/R) injury damage vessels of the retina, deteriorating its function, which can be clearly visualized by electroretinography (ERG). The aim of the present study was to evaluate the possible retinoprotective effects of systemic BGP-15, an emerging drug candidate, in an insulin resistant animal model, the Goto-Kakizaki rat, and compare these results with well-known anti-diabetics such as glibenclamide, metformin, and pioglitazone, which even led to some novel conclusions about these well-known agents. Experiments were carried out on diseased animal model (Goto-Kakizaki rats). The used methods include weight measurement, glucose-related measurements—like fasting blood sugar analysis, oral glucose tolerance test, hyperinsulinemic euglycemic glucose clamp (HEGC), and calculations of different indices from HEGC results—electroretinography and Western Blot. Beside its apparent insulin sensitization, BGP-15 was also able to counteract the retina-damaging effect of Type II diabetes comparable to the aforementioned anti-diabetics. The mechanism of retinoprotective action may include sirtuin 1 (SIRT1) and matrix metalloproteinase 9 (MMP9) enzymes, as BGP-15 was able to elevate SIRT1 and decrease MMP9 expression in the eye. Based on our results, this emerging hydroximic acid derivative might be a future target of pharmacological developments as a potential drug against the harmful consequences of diabetes, such as diabetic retinopathy.

Pharmacological Overview of the BGP-15 Chemical Agent as a New Drug Candidate for the Treatment of Symptoms of Metabolic Syndrome

BGP-15 is a new insulin sensitizer drug candidate, which was developed by Hungarian researchers. In recent years, numerous research groups have studied its beneficial effects. It is effective in the treatment of insulin resistance and it has protective effects in Duchenne muscular dystrophy, diastolic dysfunction, tachycardia, heart failure, and atrial fibrillation, and it can alleviate cardiotoxicity. BGP-15 exhibits chemoprotective properties in different cytostatic therapies, and has also proven to be photoprotective. It can additionally have advantageous effects in mitochondrial-stress-related diseases. Although the precise mechanism of the effect is still unknown to us, we know that the molecule is a PARP inhibitor, chaperone co-inducer, reduces ROS production, and is able to remodel the organization of cholesterol-rich membrane domains. In the following review, our aim was to summarize the investigated molecular mechanisms and pharmacological effects of this potential API. The main objective was to present the wide pharmacological potentials of this chemical agent.

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.

Heat-Shock Proteins in Neuroinflammation

The heat-shock response, one of the main pro-survival mechanisms of a living organism, has evolved as the biochemical response of cells to cope with heat stress. The most well-characterized aspect of the heat-shock response is the accumulation of a conserved set of proteins termed heat-shock proteins (HSPs). HSPs are key players in protein homeostasis acting as chaperones by aiding the folding and assembly of nascent proteins and protecting against protein aggregation. HSPs have been associated with neurological diseases in the context of their chaperone activity, as they were found to suppress the aggregation of misfolded toxic proteins. In recent times, HSPs have proven to have functions apart from the classical molecular chaperoning in that they play a role in a wider scale of neurological disorders by modulating neuronal survival, inflammation, and disease-specific signaling processes. HSPs are gaining importance based on their ability to fine-tune inflammation and act as immune modulators in various bodily fluids. However, their effect on neuroinflammation processes is not yet fully understood. In this review, we summarize the role of neuroinflammation in acute and chronic pathological conditions affecting the brain. Moreover, we seek to explore the existing literature on HSP-mediated inflammatory function within the central nervous system and compare the function of these proteins when they are localized intracellularly compared to being present in the extracellular milieu.

Co-treatment With BGP-15 Exacerbates 5-Fluorouracil-Induced Gastrointestinal Dysfunction

Gastrointestinal (GI) side-effects of chemotherapy present a constant impediment to efficient and tolerable treatment of cancer. GI symptoms often lead to dose reduction, delays and cessation of treatment. Chemotherapy-induced nausea, bloating, vomiting, constipation, and/or diarrhea can persist up to 10 years post-treatment. We have previously reported that long-term 5-fluorouracil (5-FU) administration results in enteric neuronal loss, acute inflammation and intestinal dysfunction. In this study, we investigated whether the cytoprotectant, BGP-15, has a neuroprotective effect during 5-FU treatment. Balb/c mice received tri-weekly intraperitoneal 5-FU (23 mg/kg/d) administration with and without BGP-15 (15 mg/kg/d) for up to 14 days. GI transit was analyzed via in vivo serial X-ray imaging prior to and following 3, 7, and 14 days of treatment. On day 14, colons were collected for assessment of ex vivo colonic motility, neuronal mitochondrial superoxide, and cytochrome c levels as well as immunohistochemical analysis of myenteric neurons. BGP-15 did not inhibit 5-FU-induced neuronal loss, but significantly increased the number and proportion of choline acetyltransferase (ChAT)-immunoreactive (IR) and neuronal nitric oxide synthase (nNOS)-IR neurons in the myenteric plexus. BGP-15 co-administration significantly increased mitochondrial superoxide production, mitochondrial depolarization and cytochrome c release in myenteric plexus and exacerbated 5-FU-induced colonic inflammation. BGP-15 exacerbated 5-FU-induced colonic dysmotility by reducing the number and proportion of colonic migrating motor complexes and increasing the number and proportion of fragmented contractions and increased fecal water content indicative of diarrhea. Taken together, BGP-15 co-treatment aggravates 5-FU-induced GI side-effects, in contrast with our previous findings that BGP-15 alleviates GI side-effects of oxaliplatin.

PARP inhibition in platinum-based chemotherapy: Chemopotentiation and neuroprotection

Cisplatin, carboplatin and oxaliplatin represent the backbone of platinum therapy for several malignancies including head and neck, lung, colorectal, ovarian, breast, and genitourinary cancer. However, the efficacy of platinum-based drugs is often compromised by a plethora of severe toxicities including sensory and enteric neuropathy. Acute and chronic neurotoxicity following platinum chemotherapy is a major constraint, contributing to dose-reductions, treatment delays, and cessation of treatment. Identifying drugs that effectively prevent these toxic complications is imperative to improve the efficacy of anti-cancer treatment and patient quality of life. Oxidative stress and mitochondrial dysfunction have been highlighted as key players in the pathophysiology of platinum chemotherapy-induced neuropathy. Inhibition of poly(ADP-ribose) polymerase (PARP), a nuclear enzyme activated upon DNA damage, has demonstrated substantial sensory and enteric neuroprotective capacity when administered in combination with platinum chemotherapeutics. Furthermore, administration of PARP inhibitors alongside platinum chemotherapy has been found to significantly improve progression-free survival in patients with breast and ovarian cancer when compared to those receiving chemotherapy alone. This review summarises the current knowledge surrounding mitochondrial damage and oxidative stress in platinum chemotherapy-induced neuropathy and highlights a potential role for PARP in chemopotentiation and neuroprotection.

Poly(adenosine diphosphate-ribose) polymerase as therapeutic target: lessons learned from its inhibitors

Poly(ADP-ribose) polymerases are a family of DNA-dependent nuclear enzymes catalyzing the transfer of ADP-ribose moieties from cellular nicotinamide-adenine-dinucleotide to a variety of target proteins. Although they have been considered as resident nuclear elements of the DNA repair machinery, recent works revealed a more intricate physiologic role of poly(ADP-ribose) polymerases with numerous extranuclear activities. Indeed, poly(ADP-ribose) polymerases participate in fundamental cellular processes like chromatin remodelling, transcription or regulation of the cell-cycle. These new insight into the physiologic roles of poly(ADP-ribose) polymerases widens the range of human pathologies in which pharmacologic inhibition of these enzymes might have a therapeutic potential. Here, we overview our current knowledge on extranuclear functions of poly(ADP-ribose) polymerases with a particular focus on the mitochondrial ones and discuss potential fields of future clinical applications.

Activation of mitochondrial fusion provides a new treatment for mitochondria-related diseases

Mitochondria fragmentation destabilizes mitochondrial membranes, promotes oxidative stress and facilitates cell death, thereby contributing to the development and the progression of several mitochondria-related diseases. Accordingly, compounds that reverse mitochondrial fragmentation could have therapeutic potential in treating such diseases. BGP-15, a hydroxylamine derivative, prevents insulin resistance in humans and protects against several oxidative stress-related diseases in animal models. Here we show that BGP-15 promotes mitochondrial fusion by activating optic atrophy 1 (OPA1), a GTPase dynamin protein that assist fusion of the inner mitochondrial membranes. Suppression of Mfn1, Mfn2 or OPA1 prevents BGP-15-induced mitochondrial fusion. BGP-15 activates Akt, S6K, mTOR, ERK1/2 and AS160, and reduces JNK phosphorylation which can contribute to its protective effects. Furthermore, BGP-15 protects lung structure, activates mitochondrial fusion, and stabilizes cristae membranes in vivo determined by electron microscopy in a model of pulmonary arterial hypertension. These data provide the first evidence that a drug promoting mitochondrial fusion in in vitro and in vivo systems can reduce or prevent the progression of mitochondria-related disorders.

Oxaliplatin-induced enteric neuronal loss and intestinal dysfunction is prevented by co-treatment with BGP-15

BACKGROUND AND PURPOSE

Gastrointestinal side effects of chemotherapy are an under-recognized clinical problem, leading to dose reduction, delays and cessation of treatment, presenting a constant challenge for efficient and tolerated anti-cancer treatment. We have found that oxaliplatin treatment results in intestinal dysfunction, oxidative stress and loss of enteric neurons. BGP-15 is a novel cytoprotective compound with potential HSP72 co-inducing and PARP inhibiting properties. In this study, we investigated the potential of BGP-15 to alleviate oxaliplatin-induced enteric neuropathy and intestinal dysfunction.

EXPERIMENTAL APPROACH

Balb/c mice received oxaliplatin (3 mg·kg^-1 ·day^-1 ) with and without BGP-15 (15 mg·kg^-1 ·day^-1 : i.p.) tri-weekly for 14 days. Gastrointestinal transit was analysed via in vivo X-ray imaging, before and after treatment. Colons were collected to assess ex vivo motility, neuronal mitochondrial superoxide and cytochrome c levels and for immunohistochemical analysis of myenteric neurons.

KEY RESULTS

Oxaliplatin-induced neuronal loss increased the proportion of neuronal NO synthase-immunoreactive neurons and increased levels of mitochondrial superoxide and cytochrome c in the myenteric plexus. These changes were correlated with an increase in PARP-2 immunoreactivity in the colonic mucosa and were attenuated by BGP-15 co-treatment. Significant delays in gastrointestinal transit, intestinal emptying and pellet formation, impaired colonic motor activity, reduced faecal water content and lack of weight gain associated with oxaliplatin treatment were restored to sham levels in mice co-treated with BGP-15.

CONCLUSION AND IMPLICATIONS

Our results showed that BGP-15 ameliorated oxidative stress, increased enteric neuronal survival and alleviated oxaliplatin-induced intestinal dysfunction, suggesting that BGP-15 may relieve the gastrointestinal side effects of chemotherapy.

BGP-15 prevents the death of neurons in a mouse model of familial dysautonomia

Hereditary sensory and autonomic neuropathy type III, or familial dysautonomia [FD; Online Mendelian Inheritance in Man (OMIM) 223900], affects the development and long-term viability of neurons in the peripheral nervous system (PNS) and retina. FD is caused by a point mutation in the gene IKBKAP/ELP1 that results in a tissue-specific reduction of the IKAP/ELP1 protein, a subunit of the Elongator complex. Hallmarks of the disease include vasomotor and cardiovascular instability and diminished pain and temperature sensation caused by reductions in sensory and autonomic neurons. It has been suggested but not demonstrated that mitochondrial function may be abnormal in FD. We previously generated an Ikbkap/Elp1 conditional-knockout mouse model that recapitulates the selective death of sensory (dorsal root ganglia) and autonomic neurons observed in FD. We now show that in these mice neuronal mitochondria have abnormal membrane potentials, produce elevated levels of reactive oxygen species, are fragmented, and do not aggregate normally at axonal branch points. The small hydroxylamine compound BGP-15 improved mitochondrial function, protecting neurons from dying in vitro and in vivo, and promoted cardiac innervation in vivo. Given that impairment of mitochondrial function is a common pathological component of neurodegenerative diseases such as amyotrophic lateral sclerosis and Alzheimer's, Parkinson's, and Huntington's diseases, our findings identify a therapeutic approach that may have efficacy in multiple degenerative conditions.

BGP-15 Protects against Oxidative Stress- or Lipopolysaccharide-Induced Mitochondrial Destabilization and Reduces Mitochondrial Production of Reactive Oxygen Species

Reactive oxygen species (ROS) play a critical role in the progression of mitochondria-related diseases. A novel insulin sensitizer drug candidate, BGP-15, has been shown to have protective effects in several oxidative stress-related diseases in animal and human studies. In this study, we investigated whether the protective effects of BGP-15 are predominantly via preserving mitochondrial integrity and reducing mitochondrial ROS production. BGP-15 was found to accumulate in the mitochondria, protect against ROS-induced mitochondrial depolarization and attenuate ROS-induced mitochondrial ROS production in a cell culture model, and also reduced ROS production predominantly at the complex I-III system in isolated mitochondria. At physiologically relevant concentrations, BGP-15 protected against hydrogen peroxide-induced cell death by reducing both apoptosis and necrosis. Additionally, it attenuated bacterial lipopolysaccharide (LPS)-induced collapse of mitochondrial membrane potential and ROS production in LPS-sensitive U-251 glioma cells, suggesting that BGP-15 may have a protective role in inflammatory diseases. However, BGP-15 did not have any antioxidant effects as shown by in vitro chemical and cell culture systems. These data suggest that BGP-15 could be a novel mitochondrial drug candidate for the prevention of ROS-related and inflammatory disease progression.

Membrane lipid therapy: Modulation of the cell membrane composition and structure as a molecular base for drug discovery and new disease treatment

Nowadays we understand cell membranes not as a simple double lipid layer but as a collection of complex and dynamic protein-lipid structures and microdomains that serve as functional platforms for interacting signaling lipids and proteins. Membrane lipids and lipid structures participate directly as messengers or regulators of signal transduction. In addition, protein-lipid interactions participate in the localization of signaling protein partners to specific membrane microdomains. Thus, lipid alterations change cell signaling that are associated with a variety of diseases including cancer, obesity, neurodegenerative disorders, cardiovascular pathologies, etc. This article reviews the newly emerging field of membrane lipid therapy which involves the pharmacological regulation of membrane lipid composition and structure for the treatment of diseases. Membrane lipid therapy proposes the use of new molecules specifically designed to modify membrane lipid structures and microdomains as pharmaceutical disease-modifying agents by reversing the malfunction or altering the expression of disease-specific protein or lipid signal cascades. Here, we provide an in-depth analysis of this emerging field, especially its molecular bases and its relevance to the development of innovative therapeutic approaches.

Curcumin Ameliorates Functional and Structural Abnormalities in Cisplatin-induced Neuropathy

Peripheral neuropathy is one of the major side effects of cisplatin; however, effective treatments are lacking. Curcumin is a polyphenol found in the root of Curcuma longa and has been shown neuroprotective against several neurological diseases. Nevertheless, its effects on cisplatin neuropathy remain unclear. This study aimed to clarify this issue by inducing neuropathy in the rats with intraperitoneal injection of cisplatin 2 mg/kg twice a week for 5 consecutive weeks. Curcumin 200 mg/kg/day was given by gavage to a group of cisplatin-treated rats during these five weeks. The results showed that cisplatin induced thermal hypoalgesia in the 5^th week which could be prevented by curcumin. In the 5^th and 8^th weeks, sciatic motor nerve conduction velocity was reduced in the cisplatin compared with the control groups. Curcumin significantly attenuated this deficit. Morphometric analysis of L4 dorsal root ganglia from the cisplatin group revealed nuclear and nucleolar atrophy including loss of neurons in the 8^th week. These alterations were significantly blocked by curcumin. Moreover, curcumin also ameliorated the reduced myelin thickness in the sciatic nerve of cisplatin-treated rats. Taken together, our findings suggest the favorable effects of curcumin on both functional and structural abnormalities in cisplatin neuropathy. Future studies are needed to clarify the exact underlying mechanisms.

Evaluation of multi-neuroprotective effects of erythropoietin using cisplatin induced peripheral neurotoxicity model

Cisplatin (CDDP) is severely neurotoxic anti-neoplastic drug that causes peripheral neuropathies with clinical signs known as chemotherapy-induced peripheral neurotoxicity. The ameliorating effects of erythropoeitin on cisplatin-induced neuropathy, which seem to be mediated by enhancing the cell resistance to side effects of cisplatin rather than by influencing the formation or repair rates of cisplatin-induced cross-links in the nuclear DNA, had been previously reported. The main objective of our study is to investigate the roles of nitro-oxidative stress, nuclear factor kappa B (NFκB) gene expressions and TNF levels on the previous reported erythropoietin anti-apoptotic neuroprotective effects during cisplatin induced neurotoxicity. The present study compared the effects of erythropoietin (50 μg/kg/d thrice weekly) on cisplatin (2mg/kg/d i.p. twice weekly for 4 weeks) induced neurophysiologic changes and the associated changes in the inflammatory mediators (TNF alpha and NFKB), oxidative stress (malondialdehyde (MDA), superoxide dismutases (SOD) and glutathione) and gene expression of both neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS). In addition, sciatic nerve pro-apoptotic and anti-apoptotic indicators (Bcl, Bax, Caspase 3) were measured. We found that concomitant administration of erythropoietin significantly reversed the cisplatin induced nitro-oxidative stress - with significant increases in sciatic nerve glutathione and superoxide dismutase antioxidant enzyme levels and a significant decrease in iNOS gene expression. We conclude that erythropoietin anti-apoptotic neuro-protective effects could partially contribute to observed antioxidant effects of erthropoietin.

The heat-shock response co-inducer arimoclomol protects against retinal degeneration in rhodopsin retinitis pigmentosa

Retinitis pigmentosa (RP) is a group of inherited diseases that cause blindness due to the progressive death of rod and cone photoreceptors in the retina. There are currently no effective treatments for RP. Inherited mutations in rhodopsin, the light-sensing protein of rod photoreceptor cells, are the most common cause of autosomal-dominant RP. The majority of mutations in rhodopsin, including the common P23H substitution, lead to protein misfolding, which is a feature in many neurodegenerative disorders. Previous studies have shown that upregulating molecular chaperone expression can delay disease progression in models of neurodegeneration. Here, we have explored the potential of the heat-shock protein co-inducer arimoclomol to ameliorate rhodopsin RP. In a cell model of P23H rod opsin RP, arimoclomol reduced P23H rod opsin aggregation and improved viability of mutant rhodopsin-expressing cells. In P23H rhodopsin transgenic rat models, pharmacological potentiation of the stress response with arimoclomol improved electroretinogram responses and prolonged photoreceptor survival, as assessed by measuring outer nuclear layer thickness in the retina. Furthermore, treated animal retinae showed improved photoreceptor outer segment structure and reduced rhodopsin aggregation compared with vehicle-treated controls. The heat-shock response (HSR) was activated in P23H retinae, and this was enhanced with arimoclomol treatment. Furthermore, the unfolded protein response (UPR), which is induced in P23H transgenic rats, was also enhanced in the retinae of arimoclomol-treated animals, suggesting that arimoclomol can potentiate the UPR as well as the HSR. These data suggest that pharmacological enhancement of cellular stress responses may be a potential treatment for rhodopsin RP and that arimoclomol could benefit diseases where ER stress is a factor.

Plasma membranes as heat stress sensors: from lipid-controlled molecular switches to therapeutic applications

The classic heat shock (stress) response (HSR) was originally attributed to protein denaturation. However, heat shock protein (Hsp) induction occurs in many circumstances where no protein denaturation is observed. Recently considerable evidence has been accumulated to the favor of the "Membrane Sensor Hypothesis" which predicts that the level of Hsps can be changed as a result of alterations to the plasma membrane. This is especially pertinent to mild heat shock, such as occurs in fever. In this condition the sensitivity of many transient receptor potential (TRP) channels is particularly notable. Small temperature stresses can modulate TRP gating significantly and this is influenced by lipids. In addition, stress hormones often modify plasma membrane structure and function and thus initiate a cascade of events, which may affect HSR. The major transactivator heat shock factor-1 integrates the signals originating from the plasma membrane and orchestrates the expression of individual heat shock genes. We describe how these observations can be tested at the molecular level, for example, with the use of membrane perturbers and through computational calculations. An important fact which now starts to be addressed is that membranes are not homogeneous nor do all cells react identically. Lipidomics and cell profiling are beginning to address the above two points. Finally, we observe that a deregulated HSR is found in a large number of important diseases where more detailed knowledge of the molecular mechanisms involved may offer timely opportunities for clinical interventions and new, innovative drug treatments. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.

Effect of synthetic eel calcitonin, elcatonin, on cold and mechanical allodynia induced by oxaliplatin and paclitaxel in rats

Oxaliplatin and paclitaxel are commonly used anti-cancer drugs, but they frequently cause peripheral neuropathic pain. In this study, we investigated the effect of elcatonin, a synthetic eel calcitonin, on oxaliplatin- and paclitaxel-induced neuropathy in rats. The rats were treated with a single dose of oxaliplatin (6 mg/kg, i.p.) or repeated doses of paclitaxel (2 mg/kg, i.p.) on 4 alternate days. Both treatments resulted in cold and mechanical allodynia. We assessed the anti-allodynic effects of subcutaneously administered elcatonin (20 U/kg/day) by using a newly developed method to provide cold stimulation (8°C) directly to the hind paw of the rats and by using the von Frey test. Elcatonin almost completely reversed the effects of both cold and mechanical allodynia. To determine the mechanism of this anti-allodynic effect, we examined the effect of elcatonin on neuropathy induced by intraplantar injection of two organic compounds: allyl isothiocyanate (1 nmol/paw), which activates transient receptor potential ankyrin-1 channels, and menthol (1.28 μmol/paw), which activates transient receptor potential ankyrin-1 and melastatin-8. Pre-administration of elcatonin almost completely prevented cold and mechanical allodynia from being induced by both compounds. These results suggest that elcatonin attenuates oxaliplatin- and paclitaxel-induced neuropathic pain by inhibiting the cellular signaling related to transient receptor potential ankyrin-1 and melastatin-8. Thus, we conclude that administration of elcatonin may improve the quality of life of cancer patients receiving chemotherapy.

Cannabinoid type-1 receptor reduces pain and neurotoxicity produced by chemotherapy

Painful peripheral neuropathy is a dose-limiting complication of chemotherapy. Cisplatin produces a cumulative toxic effect on peripheral nerves, and 30-40% of cancer patients receiving this agent experience pain. By modeling cisplatin-induced hyperalgesia in mice with daily injections of cisplatin (1 mg/kg, i.p.) for 7 d, we investigated the anti-hyperalgesic effects of anandamide (AEA) and cyclohexylcarbamic acid 3'-carbamoyl-biphenyl-3-yl ester (URB597), an inhibitor of AEA hydrolysis. Cisplatin-induced mechanical and heat hyperalgesia were accompanied by a decrease in the level of AEA in plantar paw skin. No changes in motor activity were observed after seven injections of cisplatin. Intraplantar injection of AEA (10 μg/10 μl) or URB597 (9 μg/10 μl) transiently attenuated hyperalgesia through activation of peripheral CB₁ receptors. Co-injections of URB597 (0.3 mg/kg daily, i.p.) with cisplatin decreased and delayed the development of mechanical and heat hyperalgesia. The effect of URB597 was mediated by CB₁ receptors since AM281 (0.33 mg/kg daily, i.p.) blocked the effect of URB597. Co-injection of URB597 also normalized the cisplatin-induced decrease in conduction velocity of Aα/Aβ-fibers and reduced the increase of ATF-3 and TRPV1 immunoreactivity in dorsal root ganglion (DRG) neurons. Since DRGs are a primary site of toxicity by cisplatin, effects of cisplatin were studied on cultured DRG neurons. Incubation of DRG neurons with cisplatin (4 μg/ml) for 24 h decreased the total length of neurites. URB597 (100 nM) attenuated these changes through activation of CB₁ receptors. Collectively, these results suggest that pharmacological facilitation of AEA signaling is a promising strategy for attenuating cisplatin-associated sensory neuropathy.

BGP-15, a PARP-inhibitor, prevents imatinib-induced cardiotoxicity by activating Akt and suppressing JNK and p38 MAP kinases

In this study, we investigate the cardiotoxic effects of the well-known cytostatic agent imatinib mesylate (Gleevec), and presented evidence for the cardioprotective effect of BGP-15 which is a novel insulin sensitizer. The cardiotoxic effect of imatinib mesylate was assessed in Langendorff rat heart perfusion system. The cardiac high-energy phosphate levels (creatine phosphate (PCr) and ATP) were monitored in situ by (31)P NMR spectroscopy. The protein oxidation, lipid peroxidation, and the activation of signaling pathways were determined from the freeze-clamped hearts. Prolonged treatment of the heart with imatinib mesylate (20 mg/kg) resulted in cardiotoxicity, which were characterized by the depletion of high-energy phosphates (PCr and ATP), and significantly increased protein oxidation and lipid peroxidation. Imatinib mesylate treatment-induced activation of MAP kinases (including ERK1/2, p38, and JNK) and the phosphorylation of Akt and GSK-3beta. BGP-15 (200 μM) prevented the imatinib mesylate-induced oxidative damages, attenuated the depletion of high-energy phosphates, altered the signaling effect of imatinib mesylate by preventing p38 MAP kinase and JNK activation, and induced the phosphorylation of Akt and GSK-3beta. The suppressive effect of BGP-15 on p38 and JNK activation could be significant because these kinases contribute to the cell death and inflammation in the isolated perfused heart.

Prevention of paclitaxel-induced allodynia by minocycline: Effect on loss of peripheral nerve fibers and infiltration of macrophages in rats

Background

Although paclitaxel is a frontline antineoplastic agent for treatment of solid tumors, the paclitaxel-evoked pain syndrome is a serious problem for patients. There is currently no valid drug to prevent or treat the paclitaxel-induced allodynia, partly due to lack of understanding regarding the cellular mechanism. Studies have shown that minocycline, an inhibitor of microglia/macrophage, prevented neuropathic pain and promoted neuronal survival in animal models of neurodegenerative disease. Recently, Cata et al also reported that minocycline inhibited allodynia induced by low-dose paclitaxel (2 mg/kg) in rats, but the mechanism is still unclear.

Results

Here, we investigate by immunohistochemistry the change of intraepidermal nerve fiber (IENF) in the hind paw glabrous skin, expression of macrophage and activating transcription factor 3 (ATF3) in DRG at different time points after moderate-dose paclitaxel treatment (cumulative dose 24 mg/kg; 3 × 8 mg/kg) in rats. Moreover, we observe the effect of minocycline on the IENF, macrophages and ATF3. The results showed that moderate-dose paclitaxel induced a persisted, gradual mechanical allodynia, which was accompanied by the loss of IENF in the hind paw glabrous skin and up-regulation of macrophages and ATF3 in DRG in rats. The expressions of ATF3 mainly focus on the NF200-positive cells. More importantly, we observed that pretreatment of minocycline at dose of 30 mg/kg or 50 mg/kg, but not 5 mg/kg, prevented paclitaxel-evoked allodynia. The evidence from immunohistochemistry showed that 30 mg/kg minocycline rescued the degeneration of IENF, attenuated infiltration of macrophages and up-regulation of ATF3 induced by paclitaxel treatment in rats.

Conclusions

Minocycline prevents paclitaxel-evoked allodynia, likely due to its inhibition on loss of IENF, infiltration of macrophages and up-regulation of ATF3 in rats. The finding might provide potential target for preventing paclitaxel-induced neuropathic pain.

Influence of dosing schedules on toxicity and antitumour effects of combined cisplatin and docetaxel treatment in mice

Objectives

The combination of cisplatin and docetaxel shows a better cure rate against non-small-cell lung cancer than other drug combinations in clinical studies; however, severe myelosuppression and nephrotoxicity are dose-limiting factors. The purpose of this study was to establish a suitable dosing schedule to reduce adverse effects and improve the antitumour effects.

Methods

Cisplatin and docetaxel were administered i.p. to male ICR mice simultaneously, or sequentially with either cisplatin or docetaxel first followed by the second drug 12 h later (docetaxel–cisplatin and cisplatin–docetaxel groups). Antitumour effects of these schedules were also tested in C57BL/6N mice bearing Lewis lung carcinomas.

Key findings

The simultaneous docetaxel/cisplatin group showed the lowest survival rate and the highest blood urea nitrogen (BUN) concentration. Cisplatin concentrations in the plasma and kidney were higher in the simultaneous dosing group than the sequential dosing groups. Antitumour effect was the greatest in the docetaxel–cisplatin group.

Conclusions

The docetaxel–cisplatin regimen inhibited tumour growth the best and reduced mortality and nephrotoxicity.

BGP-15 inhibits caspase-independent programmed cell death in acetaminophen-induced liver injury

It has been recently shown that acute acetaminophen toxicity results in endoplasmic reticulum redox stress and an increase in cells with apoptotic phenotype in liver. Since activation of effector caspases was absent, the relevance of caspase-independent mechanisms in acetaminophen-induced programmed cell death was investigated. BGP-15, a drug with known protective actions in conditions involving redox imbalance, has been co-administered with a single sublethal dose of acetaminophen. Proapoptotic events and outcome of the injury were investigated. ER redox alterations and early ER-stress-related signaling events induced by acetaminophen, such as ER glutathione depletion, phosphorylation of eIF2alpha and JNK and induction of the transcription factor GADD153, were not counteracted by co-treatment with BGP-15. However, BGP-15 prevented AIF mitochondria-to-nucleus translocation and mitochondrial depolarization. BGP-15 co-treatment attenuated the rate of acetaminophen-induced cell death as assessed by apoptotic index and enzyme serum release. These results reaffirm that acute acetaminophen toxicity involves oxidative stress-induced caspase-independent cell death. In addition, pharmacological inhibition of AIF translocation may effectively protect against or at least delay acetaminophen-induced programmed cell death.

Changes in tracheo-bronchial sensory neuropeptide receptor gene expression pattern in rats with cisplatin-induced sensory neuropathy

An attenuated neurogenic broncho-constriction underpinned by a decrease in sensory neuropeptide release has been shown to be characteristic of cisplatin-induced neuropathy. The present work was to explore if beyond neuropeptide release, cisplatin at a treatment schedule attaining sensory neuropathy, produced changes in the expression of the receptors of sensory neuropeptides such as somatostatin, calcitonin gene-related peptide (CGRP) and substance P (SP) in bronchial tissue of the rat. Twenty-four Wistar rats were divided into three groups. The animals in the "Treatment groups 1 and 2" were given cisplatin (1.5mgkg(-1)) and mannitol (75mgkg(-1)) over 5 days. The rats in the "Control" group were given mannitol+isotonic saline. Four animals from each group were used to study the expression pattern of the neuropeptide receptors in bronchial tissue. The levels of somatostatin receptor 4 (SSTR 4), neurokinin 1 (NK1), neurokinin 2 (NK2) and CGRP receptor expression were examined by quantitative real time polymerase chain reaction (RT-PCR) method, 11 and 22 days after the last cisplatin/vehicle dose. The cisplatin treatment significantly increased plasma somatostatin immunoreactivity and the expression of SSTR4 receptor detected both on the 11th and 22nd post-treatment days with no change in either CGRP, NK1, and NK2 receptor gene expression or plasma CGRP and substance P levels. We conclude that cisplatin neuropathy is accompanied by an increase in plasma somatostatin immunoreactivity with an increase in SSTR4 expression in rats.

Chemopotentiation by PARP inhibitors in cancer therapy

Poly(ADP-ribose) polymerases (PARP) constitute a family of enzymes involved in the regulation of many cellular processes such as DNA repair, gene transcription, cell cycle progression, cell death, chromatin functions and genomic stability. Among the 18 members identified so far, PARP-1 and PARP-2 are the only proteins stimulated by DNA strand breaks and implicated in the repair of DNA injury. Therefore, these molecules have been exploited as potential targets for the development of pharmacological strategies to increase the antitumor efficacy of chemotherapeutic agents, which induce DNA damage. PARP inhibitors have been shown to restore sensitivity of resistant tumors to methylating agents or topoisomerase I inhibitors, drugs presently used for the treatment of primary and secondary brain tumors or malignancies refractory to standard chemotherapy. Interestingly, PARP inhibitors may also provide protection from the untoward effects exerted by certain anticancer drugs, which cause oxidative stress and consequent PARP overactivation. The aim of this article is to provide a brief overview of the recent literature on preclinical studies with the specific and potent inhibitors newly synthesized.

Decreased sensory neuropeptide release in isolated bronchi of rats with cisplatin-induced neuropathy

We studied if attenuated neurogenic bronchoconstriction was associated with a change in sensory neuropeptide release in preparations from rats with cisplatin-induced neuropathy. Electrical field stimulation (100 stimuli, 20 V, 0.1 ms, 20 Hz) induced an increase in the release of somatostatin, calcitonin gene-related peptide (CGRP) and substance P determined by radioimmunoassay from baseline 0.18+/-0.01, 0.17+/-0.01 and 0.86+/-0.02, to 0.59+/-0.02, 1.77+/-0.04 and 5.96 fmol/mg wet tissue weight, respectively, in organ fluid of tracheal tubes from rats. This was significantly attenuated to post-stimulation values of 0.36+/-0.02, 0.45+/-0.02, 4.68+/-0.24 fmol/mg wet tissue weight for somatostatin, CGRP, and substance P, respectively, with a significant decrease in field stimulation-induced contraction of bronchial preparations from animals 11 days after a 5-day treatment period with cisplatin (1.5 mg/kg i.p. once a day). The cisplatin-treated animals developed sensory neuropathy characterized by a 40% decrease in femoral nerve conduction velocity. The results show that a decrease in tracheo-bronchial sensory neuropeptide release associates with feeble bronchomotor responses in rats with cisplatin-induced sensory neuropathy.

Ethosuximide reverses paclitaxel- and vincristine-induced painful peripheral neuropathy

Paclitaxel (Taxol) is one of the most effective and frequently used chemotherapeutics for the treatment of solid tumours. However, paclitaxel produces peripheral neurotoxicity with patients reporting sensory abnormalities and neuropathic pain during and often persisting after paclitaxel therapy. The mechanisms underlying this dose-limiting side effect are currently unknown and there are no validated drugs for its prevention or control. Male Sprague-Dawley rats received four intraperitoneal (i.p.) injections on alternate days of 2 mg/kg paclitaxel. Behavioural assessment using von Frey filaments and acetone showed that such paclitaxel treatment induced a pronounced mechanical and cold allodynia/hyperalgesia. Thus these studies aim to test potential analgesics on established paclitaxel-induced pain. Paclitaxel-induced pain appears to be relatively resistant to opioid therapy i.p. 4 mg/kg morphine was ineffective and i.p. 8 mg/kg morphine only elicited up to a 50% reversal of mechanical allodynia/hyperalgesia. Interestingly, a maximally tolerated dose (i.p. 0.2 mg/kg) of the potent NMDA receptor antagonist MK-801 produced no significant reversal of the mechanical allodynia/hyperalgesia suggesting that NMDA receptors have little role in paclitaxel-induced pain. Ethosuximide (i.p. 450 mg/kg) an anti-epileptic and relatively selective T-type calcium channel blocker elicited a near complete reversal of mechanical allodynia/hyperalgesia. Repetitive dosing with ethosuximide (i.p. 100 or 300 mg/kg daily for 3 days) showed a dose-related consistent reversal of mechanical allodynia/hyperalgesia with no evidence of tolerance. Ethosuximide (i.p. 300 mg/kg) also reversed paclitaxel-induced cold allodynia and vincristine-induced mechanical allodynia/hyperalgesia. These data suggest that T-type calcium channels may play a role in chemotherapy-induced neuropathy and moreover identify ethosuximide as a new potential treatment for chemotherapy-induced pain.

Effect of chronic vincristine treatment on mechanical withdrawal response and pre-pulse inhibition in the rat

Chemotherapeutic agents are associated with a number of serious side-effects. In addition to the development of peripheral neuropathy, patients often complain of additional symptoms related to attentional mechanisms. Although a great deal of interest is directed towards understanding the mechanisms underlying the development of peripheral neuropathy, there is a paucity of research that has examined the extent of impairment of attention in animals receiving chemotherapeutic agents. Therefore, the purpose of this experiment was to examine attentional mechanisms using the method of pre-pulse inhibition in animals that were chronically treated with vincristine. Although vincristine treated animals developed signs of peripheral neuropathy, there was no associated alteration of pre-pulse inhibition relative to vehicle treated animals. These results highlight the importance of continuing to develop methodology to model symptom burden in patients receiving chemotherapy.