Haloperidol induces apoptosis via the sigma2 receptor system and Bcl-XS

Possible involvement of apoptosis in the antipsychotics side effects: A minireview

Antipsychotics are used in the treatment of schizophrenia and other psychiatric disorders. Generally they are divided into typical and atypical ones, according to the fact that atypical antipychotics induce less side effects and are more effective in terms of social and cognitive improvements. Their pharmacological effects are mediated via broad range of receptors that consequently influence different cellular signaling pathways. Antipsychotics produce udesirable side effects that range from relatively minor to life-threatening ones. In vitro and in vivo studies have pointed to neurotoxic effect exerted by some antipsychotics and have shown that apoptosis might play role in some side effects induced by antipsyschotics, including tardive dyskinesia, weight gain, agranulocytosis, osteoporosis, myocarditis, etc. Although cumulative data have suggested safety of atypical antipsychotics use during pregnancy some of them have been shown to induce apoptotic neurodegenerative and structural changes in fetal brains with long-lasting impact on cognitive impairment of offsprings. Typical antipsychotics seem to be more cytotoxic than atypical ones. Recently, epidemiological studies have shown lower incidence of cancer in schizophrenic patients what suggest ability of antipsychotics to suppress risk of cancer development. Some antipsychotics have been reported to inhibit cancer cell proliferation and induce their apoptosis. Thus, antipsychotics apoptotic effect may be used as a tool in the treatmnet of some types of cancer, especially in combinatorial therapies. In this minireview, we focused on pro- and anti-apototic or "Dr. Jekyll and Mr. Hyde" effects of antipsychotics, which can be involved in their side effects, as well as their promising therapeutical indications. This article is protected by copyright. All rights reserved.

Cannabinoids in the management of behavioral, psychological, and motor symptoms of neurocognitive disorders: a mixed studies systematic review

Aim

We undertook this systematic review to determine the efficacy and safety of cannabis-based medicine as a treatment for behavioral, psychological, and motor symptoms associated with neurocognitive disorders.

Methods

We conducted a PRISMA-guided systematic review to identify studies using cannabis-based medicine to treat behavioral, psychological, and motor symptoms among individuals with Alzheimer's disease (AD) dementia, Parkinson’s disease (PD), and Huntington’s disease (HD). We considered English-language articles providing original data on three or more participants, regardless of design.

Findings

We identified 25 studies spanning 1991 to 2021 comprised of 14 controlled trials, 5 pilot studies, 5 observational studies, and 1 case series. In most cases, the cannabinoids tested were dronabinol, whole cannabis, and cannabidiol, and the diagnoses included AD (n = 11), PD (n = 11), and HD (n = 3). Primary outcomes were motor symptoms (e.g., dyskinesia), sleep disturbance, cognition, balance, body weight, and the occurrence of treatment-emergent adverse events.

Conclusions

A narrative summary of the findings from the limited number of studies in the area highlights an apparent association between cannabidiol-based products and relief from motor symptoms in HD and PD and an apparent association between synthetic cannabinoids and relief from behavioral and psychological symptoms of dementia across AD, PD, and HD. These preliminary conclusions could guide using plant-based versus synthetic cannabinoids as safe, alternative treatments for managing neuropsychiatric symptoms in neurocognitive vulnerable patient populations.

Bi-phasic dose response in the preclinical and clinical developments of sigma-1 receptor ligands for the treatment of neurodegenerative disorders

Introduction: The sigma-1 receptor (S1R) is attracting much attention for disease-modifying therapies in neurodegenerative diseases. It is a conserved protein, present in plasma and endoplasmic reticulum (ER) membranes and enriched in mitochondria-associated ER membranes (MAMs). It modulates ER-mitochondria Ca2+ transfer and ER stress pathways. Mitochondrial and MAM dysfunctions contribute to neurodegenerative processes in diseases such as Alzheimer, Parkinson, Huntington or Amyotrophic Lateral Sclerosis. Interestingly, the S1R can be activated by small druggable molecules and accumulating preclinical data suggest that S1R agonists are effective protectants in these neurodegenerative diseases.Area covered: In this review, we will present the data showing the high therapeutic potential of S1R drugs for the treatment of neurodegenerative diseases, focusing on pridopidine as a potent and selective S1R agonist under clinical development. Of particular interest is the bi-phasic (bell-shaped) dose-response effect, representing a common feature of all S1R agonists and described in numerous preclinical models in vitro, in vivo and in clinical trials.Expert opinion: S1R agonists modulate inter-organelles communication altered in neurodegenerative diseases and activate intracellular survival pathways. Research will continue growing in the future. The particular cellular nature of this chaperone protein must be better understood to facilitate the clinical developement of promising molecules.

A Mechanistic Investigation on the Anticancer Properties of SYA013, a Homopiperazine Analogue of Haloperidol with Activity against Triple Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) is one of the most malignant cancers associated with early metastasis, poor clinical prognosis, and high recurrence rate. TNBC is a distinct subtype of breast cancer that lacks estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 receptors (HER2). Development of effective TNBC therapies has been limited partially due to the lack of specific molecular targets and chemotherapy involving different cytotoxic drugs suffers from significant side effects and drug-resistance development. Therefore, there is an unmet need for the development of novel and efficient therapeutic drugs with reduced side effects to treat TNBC. We have previously reported that certain analogues of haloperidol (a typical antipsychotic drug used for treating mental/mood disorders such as schizophrenia and bipolar disorder) suppress the viability of a variety of solid tumor cell lines, and we have identified 4-(4-(4-chlorophenyl)-1,4-diazepan-1-yl)-1-(4-fluoro-phenyl)butan-1-one (SYA013) with such antiproliferative properties. Interestingly, unlike haloperidol, SYA013 shows moderate selectivity toward σ2 receptors. In this study, we explored the potential of SYA013 in modulating the important biological events associated with cell survival and progression as well as the mechanistic aspects of apoptosis in a representative TNBC cell line (MDA-MB-231). Our results indicate that SYA013 inhibits the proliferation of MDA-MB-231 cells in a concentration-dependent manner and suppresses cell migration and invasion. Apoptotic studies were also conducted in MDA-MB-468 cells (cells derived from a 51-year old Black female with metastatic adenocarcinoma of the breast.). In addition, we have demonstrated that SYA013 induces MDA-MB-231 cell death through the intrinsic apoptotic pathway and may suppress tumor progression and metastasis. Taken together, our study presents a mechanistic pathway of the anticancer properties of SYA013 against TNBC cell lines and suggests a potential for exploring SYA013 as a lead agent for development against TNBC.

Ca2+ signaling as a mechanism of haloperidol-induced cytotoxicity in human astrocytes and assessing the protective role of a Ca2+ chelator

Haloperidol, a typical antipsychotic medication, has been shown to possess various biological effects in different brain models. However, the impact of haloperidol on Ca²⁺ signaling in astrocytes is elusive. This study explored the effect of haloperidol on cytosolic free Ca²⁺ levels ([Ca²⁺]_i) and viability, and established these two connections in Gibco® Human Astrocytes (GHAs) and DI TNC1 rat astrocytes. Haloperidol (5-20 μM) caused [Ca²⁺]_i rises in a concentration-dependent manner in GHAs but not in DI TNC1 cells. Furthermore, removal of extracellular Ca²⁺ reduced haloperidol's effect by approximately 30% in GHAs. Haloperidol (20-40 μM) evoked concentration-dependent cytotoxicity in GHAs and DI TNC1 cells. However, chelating cytosolic Ca²⁺ with the Ca²⁺ chelator BAPTA/AM significantly reversed haloperidol's cytotoxicity only in GHAs. In GHAs, haloperidol-induced Ca²⁺ entry was inhibited by store-operated Ca²⁺ modulators (2-APB and SKF96365) and the protein kinase C (PKC) inhibitor GF109203X. This Ca²⁺ entry induced by haloperidol was confirmed by Mn²⁺ entry-induced quench of fura-2 fluorescence. In Ca²⁺-free medium, treatment with the endoplasmic reticulum Ca²⁺ pump inhibitor 2,5-di-tert-butylhydroquinone (BHQ) abolished haloperidol-induced [Ca²⁺]_i rises. Conversely, treatment with haloperidol inhibited 45% of BHQ-evoked [Ca²⁺]_i rises. Moreover, haloperidol-induced Ca²⁺ release from the endoplasmic reticulum was abolished by inhibition of phospholipase C (PLC) by U73122. Together, in GHAs but not in DI TNC1 cells, haloperidol caused Ca²⁺-associated cell death, induced Ca²⁺ entry via PKC-sensitive store-operated Ca²⁺ channels, and evoked PLC-dependent Ca²⁺ release from the endoplasmic reticulum. The protective effect of Ca²⁺ chelating on haloperidol-induced cytotoxicity in human astrocytes was also demonstrated.

Allosteric modulation of sigma receptors by BH3 mimetics ABT-737, ABT-263 (Navitoclax) and ABT-199 (Venetoclax)

ABT-737, ABT-263 (Navitoclax) and ABT-199 (Venetoclax) are under intensive preclinical and clinical investigation as treatments for hematologic and other malignancies. These small molecules mimic pro-death B-cell lymphoma-2 (Bcl-2) Homology 3 (BH3) domain-only proteins. They also bear a structural resemblance to certain sigma (σ) receptor ligands. Moreover, the Bcl-2 and σ receptor protein families are both located primarily at the endoplasmic reticulum, mediate cell death and survival through protein-protein interactions, and physically associate. Accordingly, we examined the ability of the ABT series of BH3 mimetics to interact with σ receptors using radioligand-binding techniques. Negative allosteric modulation of [3H](+)-pentazocine, an agonist, binding to σ1 receptors in guinea pig brain membranes was observed for ABT-737, ABT-263 and ABT-199. Findings included reduction of specific binding to distinct plateaus in concentration-dependent fashion, significant slowing of radioligand dissociation kinetics, and decreases in radioligand affinity with no or modest changes in maximal receptor densities. Using a ternary complex model, dissociation constants (KX) for modulator binding to the σ1 receptor ranged from 1 to 2.5 μM, while negative cooperativity factors (α), representing the changes in affinity of ligand and modulator when bound as a ternary complex with the receptor, ranged from 0.15 to 0.42. These observations were extended and reinforced by studies using intact small cell (NCI-H69) and non-small cell (NCI-H23) lung cancer cells, and by using an antagonist σ1 receptor radioligand, E-N-1-(3'-[125I]iodoallyl)-N'-4-(3″,4″-dimethoxyphenethyl)piperazine, in mouse brain membranes. By contrast, exploratory studies indicate marked enhancement of the σ2 receptor binding of [3H]1,3-di-(o-tolyl)guanidine/(+)-pentazocine in NCI-H23 cells and guinea pig brain membranes. These findings raise intriguing questions regarding mechanism and potential functional outcomes.

A Structure- and Ligand-Based Virtual Screening of a Database of "Small" Marine Natural Products for the Identification of "Blue" Sigma-2 Receptor Ligands

Sigma receptors are a fascinating receptor protein class whose ligands are actually under clinical evaluation for the modulation of opioid analgesia and their use as positron emission tomography radiotracers. In particular, peculiar biological and therapeutic functions are associated with the sigma-2 (σ₂) receptor. The σ₂ receptor ligands determine tumor cell death through apoptotic and non-apoptotic pathways, and the overexpression of σ₂ receptors in several tumor cell lines has been well documented, with significantly higher levels in proliferating tumor cells compared to quiescent ones. This acknowledged feature has found practical application in the development of cancer cell tracers and for ligand-targeting therapy. In this context, the development of new ligands that target the σ₂ receptors is beneficial for those diseases in which this protein is involved. In this paper, we conducted a search of new potential σ₂ receptor ligands among a database of 1517 “small” marine natural products constructed by the union of the Seaweed Metabolite and the Chemical Entities of Biological Interest (ChEBI) Databases. The structures were passed through two filters that were constituted by our developed two-dimensional (2D) and three-dimensional Quantitative Structure-Activity Relationship (3D-QSAR) statistical models, and successively docked upon a σ₂ receptor homology model that we built according to the FASTA sequence of the σ₂/TMEM97 (SGMR2_HUMAN) receptor.

Synthesis and evaluation of haloperidol metabolite II prodrugs as anticancer agents

The use of haloperidol metabolite II (HP-metabolite II) prodrugs is an emerging strategy in the treatment of cancer. HP-metabolite II exhibits antiproliferative properties at micromolar concentrations inducing apoptosis in different types of cancer. Thus, the application of the prodrug approach appears as a useful method leading to much more desirable pharmacokinetic and pharmacodynamic properties. Some studies have shown that the esterification of the hydroxyl group of HP-metabolite II with 4-phenylbutiric acid (4-PBA) or valproic acid enhances the anticancer therapeutic potency. The current progresses in the design, synthesis and evaluation of anticancer activity of HP metabolite II prodrugs will be discussed in this review.

Hyphenated 3D-QSAR statistical model-scaffold hopping analysis for the identification of potentially potent and selective sigma-2 receptor ligands

A 3D quantitative structure-activity relationship (3D-QSAR) model for predicting the σ₂ receptor affinity has been constructed with the aim of providing a useful tool for the identification, design, and optimization of novel σ₂ receptor ligands. The model has been built using a set of 500 selective σ₂ receptor ligands recovered from the sigma-2 receptor selective ligand database (S2RSLDB) and developed with the software Forge. The present model showed high statistical quality as confirmed by its robust predictive potential and satisfactory descriptive capability. The drawn up 3D map allows for a prompt visual comprehension of the electrostatic, hydrophobic, and shaping features underlying σ₂ receptor ligands interaction. A theoretic approach for the generation of new lead compounds with optimized σ₂ receptor affinity has been performed by means of scaffold hopping analysis. Obtained results further confirmed the validity of our model being some of the identified moieties have already been successfully employed in the development of potent σ₂ receptor ligands. For the first time is herein reported a 3D-QSAR model which includes a number of chemically diverse σ₂ receptor ligands and well accounts for the individual ligands affinities. These features will ensure prospectively advantageous applications to speed up the identification of new potent and selective σ₂ receptor ligands.

Targeting Nanocarriers with Anisamide: Fact or Artifact?

Encapsulating chemotherapeutics in nanoparticles can reduce the side effects of intravenous administration and improve their antitumor efficacy. Additionally, surface decoration of the nanocarriers with tumor-targeting ligands may enhance their specificity for cancer cells overexpressing the corresponding ligand-binding counterpart. The focus here is on anisamide, a low-molecular-weight benzamide derivative used as a tumor-directing moiety in functionalized nanosystems, based on its alleged interaction with Sigma receptors. The scintigraphic agents that initially inspired the use of anisamide for tumor targeting are described, and the published anisamide-tethered nanocarrier formulations are reviewed, together with a critical overview of the ligand's tumor-targeting properties. Moreover, anisamide's putative but dubious cellular target, the Sigma-1 receptor, is discussed with regard to its subcellular localization and implications in cancer. Data from in vivo studies reveal that the effect of anisamide on the antitumor efficacy of the decorated nanosystems varies considerably among the published reports. Together with the evidence questioning the interaction of anisamide with the Sigma receptors, the variability of anisamide's effect on the tumor deposition and the antitumor efficacy of the decorated drug carriers calls into question the extent of the ligand's tumor-targeting effect. Further research is necessary to elucidate the ligand's utility in tumor targeting.

Sigma-2 receptor agonist derivatives of 1-Cyclohexyl-4-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)propyl]piperazine (PB28) induce cell death via mitochondrial superoxide production and caspase activation in pancreatic cancer

Background

Despite considerable efforts by scientific research, pancreatic cancer is the fourth leading cause of cancer related mortalities. Sigma-2 receptors, which are overexpressed in several tumors, represent promising targets for triggering selective pancreatic cancer cells death.

Methods

We selected five differently structured high-affinity sigma-2 ligands (PB28, PB183, PB221, F281 and PB282) to study how they affect the viability of diverse pancreatic cancer cells (human cell lines BxPC3, AsPC1, Mia PaCa-2, and Panc1 and mouse Panc-02, KCKO and KP-02) and how this is reflected in vivo in a tumor model.

Results

Important cytotoxicity was shown by the compounds in the aggressive Panc02 cells, where cytotoxic activity was caspase-3 independent for four of the five compounds. However, both cytotoxicity and caspase-3 activation involved generation of Reactive Oxygen Species (ROS), which could be partially reverted by the lipid antioxidant α-tocopherol, but not by the hydrophilic N-acetylcysteine (NAC) indicating crucial differences in the intracellular sites exposed to oxidative stress induced by sigma-2 receptor ligands. Importantly, all the compounds strongly increased the production of mitochondrial superoxide radicals except for PB282. Despite a poor match between in vitro and the in vivo efficacy, daily treatment of C57BL/6 mice bearing Panc02 tumors resulted in promising effects with PB28 and PB282 which were similar compared to the current standard-of-care chemotherapeutic gemcitabine without showing signs of systemic toxicities.

Conclusions

Overall, this study identified differential sensitivities of pancreatic cancer cells to structurally diverse sigma-2 receptor ligands. Of note, we identified the mitochondrial superoxide pathway as a previously unrecognized sigma-2 receptor-activated process, which encourages further studies on sigma-2 ligand-mediated cancer cell death for the targeted treatment of pancreatic tumors.

Sigma1 Pharmacology in the Context of Cancer

Sigma1 (also known as sigma-1 receptor, Sig1R, σ1 receptor) is a unique pharmacologically regulated integral membrane chaperone or scaffolding protein. The majority of publications on the subject have focused on the neuropharmacology of Sigma1. However, a number of publications have also suggested a role for Sigma1 in cancer. Although there is currently no clinically used anti-cancer drug that targets Sigma1, a growing body of evidence supports the potential of Sigma1 ligands as therapeutic agents to treat cancer. In preclinical models, compounds with affinity for Sigma1 have been reported to inhibit cancer cell proliferation and survival, cell adhesion and migration, tumor growth, to alleviate cancer-associated pain, and to have immunomodulatory properties. This review will highlight that although the literature supports a role for Sigma1 in cancer, several fundamental questions regarding drug mechanism of action and the physiological relevance of aberrant SIGMAR1 transcript and Sigma1 protein expression in certain cancers remain unanswered or only partially answered. However, emerging lines of evidence suggest that Sigma1 is a component of the cancer cell support machinery, that it facilitates protein interaction networks, that it allosterically modulates the activity of its associated proteins, and that Sigma1 is a selectively multifunctional drug target.

Findings questioning the involvement of Sigma-1 receptor in the uptake of anisamide-decorated particles

Anisamide is a small benzamide previously suggested as a tumor-targeting ligand for nanocarriers and it has been shown to enhance tumor uptake in vitro as well as in vivo when grafted on the nanoparticle surface. Anisamide has been hypothesized to interact with the Sigma-1 receptor, based on the binding of larger benzamides, which contain anisamide in their structure, to this receptor. However, the interaction between anisamide and Sigma-1 receptor has never been thoroughly studied. We developed fluorescent PEGylated particles decorated with anisamide, which were preferentially taken up in vitro by melanoma cells compared to macrophages. The anisamide-decorated particles were used to study their interaction with the Sigma-1 receptor. The absence of competition of Sigma-1 receptor ligands for the particle uptake was a first indication that the receptor might not be involved in the uptake process. In addition, the extent of particle uptake did not correlate with the levels of cellular expression of Sigma-1 receptor in the cell models tested. Immunostaining of the receptor on melanoma cells revealed intracellular localization, indirectly excluding the possibility of anisamide binding to the receptor when grafted on the particles. All these data question the previously suggested Sigma-1 receptor-mediated uptake of the anisamide-decorated particles, a finding which may have an impact on the use of anisamide as a targeting ligand.

Targeted pancreatic cancer therapy with the small molecule drug conjugate SW IV-134

Pancreatic adenocarcinoma is highly resistant to conventional therapeutics and has been shown to evade apoptosis by deregulation of the X-linked and cellular inhibitors of apoptosis proteins (XIAP and cIAP). Second mitochondria-derived activator of caspases (Smac) induces and amplifies cell death by reversing the anti-apoptotic activity of IAPs. Thus, Smac-derived peptide analogues (peptidomimetics) have been developed and shown to represent promising cancer therapeutics. Sigma-2 receptors are overexpressed in many proliferating tumor cells including pancreatic cancer. Selected ligands to this receptor are rapidly internalized by cancer cells. These characteristics have made the sigma-2 receptor an attractive target for drug delivery because selective delivery to cancer cells has the potential to increase therapeutic efficacy while minimizing toxicity to normal tissues. Here, we describe the initial characterization of SW IV-134, a chemically linked drug conjugate between the sigma-2 ligand SW43 and the Smac mimetic SW IV-52 as a novel treatment option for pancreatic adenocarcinoma. The tumor killing characteristics of our dual-domain therapeutic SW IV-134 was far greater than either component in isolation or in an equimolar mix and suggests enhanced cellular delivery when chemically linked to the sigma-2 ligand. One of the key findings was that SW IV-134 retained target selectivity of the Smac cargo with the involvement of the NF-κB/TNFα signaling pathway. Importantly, SW IV-134 slowed tumor growth and improved survival in murine models of pancreatic cancer. Our data support further study of this novel therapeutic and this drug delivery strategy because it may eventually benefit patients with pancreatic cancer.

Synthesis and in vitro evaluation of tetrahydroisoquinolines with pendent aromatics as sigma-2 (σ2) selective ligands

Sigma-2 selective ligands – a SAR study showing increased potency and selectivity with derivatives showing the potential to be converted into radiolabelled ligands.

Neuroprotective targets through which 6-acetyl-3-(4-(4-(4-fluorophenyl)piperazin-1-yl)butyl)benzo[d]oxazol-2(3H)-one (SN79), a sigma receptor ligand, mitigates the effects of methamphetamine in vitro

Exposure to high or repeated doses of methamphetamine can cause hyperthermia and neurotoxicity, which are thought to increase the risk of developing a variety of neurological conditions. Sigma receptor antagonism can prevent methamphetamine-induced hyperthermia and neurotoxicity, but the underlying cellular targets through which the neuroprotection is conveyed remain unknown. Differentiated NG108-15 cells were thus used as a model system to begin elucidating the neuroprotective mechanisms targeted by sigma receptor antagonists to mitigate the effects of methamphetamine. In differentiated NG108-15 cells, methamphetamine caused the generation of reactive oxygen/nitrogen species, an increase in PERK-mediated endoplasmic reticulum stress and the activation of caspase-3, -8 and -9, ultimately resulting in apoptosis at micromolar concentrations, and necrotic cell death at higher concentrations. The sigma receptor antagonist, 6-acetyl-3-(4-(4-(4-fluorophenyl)piperazin-1-yl)butyl)benzo[d]oxazol-2(3H)-one (SN79), attenuated methamphetamine-induced increases in reactive oxygen/nitrogen species, activation of caspase-3, -8 and -9 and accompanying cellular toxicity. In contrast, 1,3-di(2-tolyl)-guanidine (DTG), a sigma receptor agonist, shifted the dose response curve of methamphetamine-induced cell death towards the left. To probe the effect of temperature on neurotoxicity, NG108-15 cells maintained at an elevated temperature (40 °C) exhibited a significant and synergistic increase in cell death in response to methamphetamine, compared to cells maintained at a normal cell culture temperature (37 °C). SN79 attenuated the enhanced cell death observed in the methamphetamine-treated cells at 40 °C. Together, the data demonstrate that SN79 reduces methamphetamine-induced reactive oxygen/nitrogen species generation and caspase activation, thereby conveying neuroprotective effects against methamphetamine under regular and elevated temperature conditions.

Mechanisms of antidepressant action: an integrated dopaminergic perspective

The molecular mechanisms that cause and maintain the major depressive disorder (MDD) are currently unknown. Consistently, antidepressant treatments are characterized by insufficient success rates. This causes high social costs and severe personal sufferings. In the present review we analyze some of the paradigms that are used to explain MDD, particularly from the perspective of the dopaminergic (DA) system. DA has been more classically associated with psychosis and substance abuse disorders, even though a role of DA in MDD has been proposed as well and some antidepressants with DA profile exist. In the present work, we review some of the molecular mechanisms that underpin MDD from the perspective of the dopaminergic system, in the hope of unifying some of the major theories of MDD - the monoaminergic, inflammatory, epigenetics, neurotrophin and anti-apoptotic theories. Several shared components of these theories are highlighted, partially accounted by the functions of the DA system (see supplementary video).

Structure-activity study to develop cationic lipid-conjugated haloperidol derivatives as a new class of anticancer therapeutics

Haloperidol (HP), a neuroleptic drug, shows high affinity toward σ receptors (SR). HP and reduced-HP at higher concentration were known to induce apoptosis in SR-overexpressing carcinomas and melanomas. Herein, we report the development of cationic lipid-conjugated haloperidol as a new class of anticancer therapeutics. In comparison to HP, the C-8 carbon chain analogue (HP-C8) showed significantly high, SR-assisted antiproliferative activity against cancer cells via caspase-3-mediated apoptosis and down-regulation of pAkt. Moreover, melanoma tumor aggressiveness in HP-C8-treated mice was significantly lower than that in HP-treated mice. HP-C8 simultaneously reduced Akt-protein level and increased Bax/Bcl-2 ratio in vascular endothelial cells, thereby indicating a possible protein kinase down-regulatory and apoptosis inducing role in tumor-associated vascular cells. In conclusion, we developed σ receptor-targeting cationic lipid-modified HP derivatives as a promising class of anticancer therapeutic that concurrently affects cancer and tumor environment associated angiogenic vascular cells through induction of apoptosis and Akt protein down-regulation.

The novel sigma-2 receptor ligand SW43 stabilizes pancreas cancer progression in combination with gemcitabine

Background

Sigma-2 receptors are over-expressed in proliferating cancer cells, making an attractive target for the targeted treatment of pancreatic cancer. In this study, we investigated the role of the novel sigma-2 receptor ligand SW43 to induce apoptosis and augment standard chemotherapy.

Results

The binding affinity for sigma-2 ligands is high in pancreas cancer, and they induce apoptosis with a rank order of SV119 < SW43 < SRM in vitro. Combining these compounds with gemcitabine further increased apoptosis and decreased viability. Our in vivo model showed that sigma-2 ligand treatment decreased tumor volume to the same extent as gemcitabine. However, SW43 combination treatment with gemcitabine was superior to the other compounds and resulted in stabilization of tumor volume during treatment, with minimal toxicities.

Conclusions

This study shows that the sigma-2 ligand SW43 has the greatest capacity to augment gemcitabine in a pre-clinical model of pancreas cancer and has provided us with the rationale to move this compound forward with clinical investigations for patients with pancreatic cancer.

Roles of the Akt/GSK-3 and Wnt signaling pathways in schizophrenia and antipsychotic drug action

Dopamine D(2) receptor antagonism is a unifying property of all antipsychotic drugs in clinical use. Remarkably, the effector molecules through which these medications exert their actions remain poorly characterized. Increasing attention is being focused on Akt/glycogen synthase kinase-3 (GSK-3) and wingless (Wnt) signaling pathways, which have been associated with schizophrenia in a number of genetic and postmortem studies. Antipsychotic medications may treat symptoms of psychosis, at least in part, through modulation of levels and activity of Akt, GSK-3, and Wnt-related intracellular signaling. The authors review evidence that Akt/GSK-3 and Wnt-related pathways are involved in the pathogenesis of schizophrenia as well as details of intracellular events related to these molecules mediated by both typical and atypical antipsychotic medications. Further study of Akt/GSK-3 and Wnt signaling may ultimately lead to alternative therapeutics of schizophrenia-related disorders.

The pharmacology of sigma-1 receptors

Originally considered an enigmatic protein, the sigma-1 receptor has recently been identified as a unique ligand-regulated molecular chaperone in the endoplasmic reticulum of cells. This discovery causes us to look back at the many proposed roles of this receptor, even before its molecular function was identified, in many diseases such as methamphetamine or cocaine addiction, amnesia, pain, depression, Alzheimer's disease, stroke, retinal neuroprotection, HIV infection, and cancer. In this review, we examine the reports that have clearly shown an agonist-antagonist relationship regarding sigma-1 receptors in models of those diseases and also review the relatively known mechanisms of action of sigma-1 receptors in an attempt to spur the speculation of readers on how the sigma-1 receptor at the endoplasmic reticulum might relate to so many diseases. We found that the most prominent action of sigma-1 receptors in biological systems including cell lines, primary cultures, and animals is the regulation and modulation of voltage-regulated and ligand-gated ion channels, including Ca(2+)-, K(+)-, Na(+), Cl(-), and SK channels, and NMDA and IP3 receptors. We found that the final output of the action of sigma-1 receptor agonists is to inhibit all above-mentioned voltage-gated ion channels, while they potentiate ligand-gated channels. The inhibition or potentiation induced by agonists is blocked by sigma-1 receptor antagonists. Other mechanisms of action of sigma-1 receptors, and to some extent those of sigma-2 receptors, were also considered. We conclude that the sigma-1 and sigma-2 receptors represent potential fruitful targets for therapeutic developments in combating many human diseases.

Effect of chronic treatment of haloperidol on the rat liver: a stereological and histopathological study

Haloperidol is commonly used in therapy for patients with acute and chronic schizophrenia. Because it can have some adverse effects on specific target organs such as the liver, we analyzed whether haloperidol exerts a toxic effect on rat liver by means of stereological and histopathological methods. Fifteen adult male rats, divided into three groups, were used in the experiments. Once a day for 6 weeks, either saline or 0.4 or 0.8 mg kg(-1) doses of haloperidol were given interperitoneally to the control, low-dose, and high-dose groups, respectively. At the end of the experiment, rats were killed by an overdose of a general anesthetic, and the livers were dissected out, fixed for sectioning, and evaluated using stereological and histopathological methods. Hepatocyte numbers were found to be 271.672, 291.072, and 238.415 hepatocytes per cubic millimeter in the liver of the control, low-dose, and high-dose groups, respectively. The differences between high-dose and control groups and also between high-dose and low-dose groups were significant (p < 0.05). Our histopathological findings at both the structural and the ultra-structural level were confirmed by stereological estimations. Results suggest a relationship between haloperidol dose and toxic effects on the liver, and they indicate that a high dose of haloperidol may result in irreversible liver damage.

Erythropoietin prevents haloperidol treatment-induced neuronal apoptosis through regulation of BDNF

Functional alterations in the neurotrophin, brain-derived neurotrophic factor (BDNF) have recently been implicated in the pathophysiology of schizophrenia. Furthermore, animal studies have indicated that several antipsychotic drugs have time-dependent (and differential) effects on BDNF levels in the brain. For example, our previous studies in rats indicated that chronic treatment with the conventional antipsychotic, haloperidol, was associated with decreases in BDNF (and other neurotrophins) in the brain as well as deficits in cognitive function (an especially important consideration for the therapeutics of schizophrenia). Additional studies indicate that haloperidol has other deleterious effects on the brain (eg increased apoptosis). Despite such limitations, haloperidol remains one of the more commonly prescribed antipsychotic agents worldwide due to its efficacy for the positive symptoms of schizophrenia and its low cost. Interestingly, the hematopoietic hormone, erythropoietin, in its recombinant human form rhEPO has been reported to increase the expression of BDNF in neuronal tissues and to have neuroprotective effects. Such observations provided the impetus for us to investigate in the present study whether co-treatment of rhEPO with haloperidol could sustain the normal levels of BDNF in vivo in rats and in vitro in cortical neuronal cultures and further, whether BDNF could prevent haloperidol-induced apoptosis through the regulation of key apoptotic/antiapoptotic markers. The results indicated that rhEPO prevented the haloperidol-induced reduction in BDNF in both in vivo and in vitro experimental conditions. The sustained levels of BDNF in rats with rhEPO prevented the haloperidol-induced increase in caspase-3 (p<0.05) and decrease in Bcl-xl (p<0.01) protein levels. Similarly, in vitro experiments showed that rhEPO prevented (p<0.001) the haloperidol-induced neuronal cell death as well as the decrease in Bcl-xl levels (p<0.01). These findings may have significant implications for the development of neuroprotective strategies to improve clinical outcomes when antipsychotic drugs are used chronically.

Gene expression on liver toxicity induced by administration of haloperidol in rats with severe fatty liver

Sudden deaths are often encountered in schizophrenic patients prescribed with antipsychotic drugs, and fatty liver may be more prevalent among patients with schizophrenia. The aim of this study is to investigate the adverse effects of antipsychotic drugs on fatty liver. We administered haloperidol intraperitoneally to fatty liver rats and examined the mRNA expression in the liver. Basic expressions of cytochrome P450 (CYP)1A2, CYP2C11 and CYP3A2 decreased, and response of these CYPs to haloperidol was reduced in the fatty liver. Metabolism of haloperidol was also suppressed in the fatty liver rats. Moreover, hepatic injury by administration of haloperidol was shown pathohistologically and molecular-biologically in severe fatty liver. These results suggest that fatty liver increases susceptibility to adverse effects of haloperidol, possibly leading to life-threatening events. It should be noted by clinicians that excessive dose of antipsychotic drugs may be more harmful in patients with fatty liver.

Chemo brain - a psychotropic drug phenomenon?

The phenomenon of 'chemo brain' refers to a cluster of potentially long-lasting, cognitive deficiencies which are caused by systemic cancer treatments. While the oncology community has gradually acknowledged the existence of chemo brain as an unintended consequence of anti-neoplastic therapies, other fields of medicine have been less astute. Preliminary research evidence has suggested a role for many existing psychopharmaceuticals in fighting malignancies, based upon the capacity of these drugs to modify gene expression, cell turnover, and cell death (e.g., apoptosis). The author presents the hypothesis that the same mechanisms which suppress the growth and survival of cancer cells may pose similar hazards to non-diseased neurons, thereby inducing the cognitive changes which oncologists have come to associate with chemo brain. The article discusses the specific examples of valproic acid, clomipramine, and fluoxetine as treatments for solid tumors, primary brain tumors, and Burkitt's lymphoma, respectively. Clinicians, regardless of specialization, are encouraged to consider the potential reality of psychotropic chemo brain, in order to avoid or limit the use of medications which cause it, and in order to prioritize the delivery of rehabilitative strategies in an effort to mitigate or reverse its features.

Selective sigma-2 ligands preferentially bind to pancreatic adenocarcinomas: applications in diagnostic imaging and therapy

BACKGROUND

Resistance to modern adjuvant treatment is in part due to the failure of programmed cell death. Therefore the molecules that execute the apoptotic program are potential targets for the development of anti-cancer therapeutics. The sigma-2 receptor has been found to be over-expressed in some types of malignant tumors, and, recently, small molecule ligands to the sigma-2 receptor were found to induce cancer cell apoptosis.

RESULTS

The sigma-2 receptor was expressed at high levels in both human and murine pancreas cancer cell lines, with minimal or limited expression in normal tissues, including: brain, kidney, liver, lung, pancreas and spleen. Micro-PET imaging was used to demonstrate that the sigma-2 receptor was preferentially expressed in tumor as opposed to normal tissues in pancreas tumor allograft-bearing mice. Two structurally distinct sigma-2 receptor ligands, SV119 and WC26, were found to induce apoptosis to mice and human pancreatic cancer cells in vitro and in vivo. Sigma-2 receptor ligands induced apoptosis in a dose dependent fashion in all pancreatic cell lines tested. At the highest dose tested (10 muM), all sigma-2 receptor ligands induced 10-20% apoptosis in all pancreatic cancer cell lines tested (p < 0.05). In pancreas tumor allograft-bearing mice, a single bolus dose of WC26 caused approximately 50% apoptosis in the tumor compared to no appreciable apoptosis in tumor-bearing, vehicle-injected control animals (p < 0.0001). WC26 significantly slowed tumor growth after a 5 day treatment compared to vehicle-injected control animals (p < 0.0001) and blood chemistry panels suggested that there is minimal peripheral toxicity.

CONCLUSION

We demonstrate a novel therapeutic strategy that induces a significant increase in pancreas cancer cell death. This strategy highlights a new potential target for the treatment of pancreas cancer, which has little in the way of effective treatments.