Repurposing antipsychotics as glioblastoma therapeutics: Potentials and challenges

High-throughput identification of repurposable neuroactive drugs with potent anti-glioblastoma activity

Glioblastoma, the most aggressive primary brain cancer, has a dismal prognosis, yet systemic treatment is limited to DNA-alkylating chemotherapies. New therapeutic strategies may emerge from exploring neurodevelopmental and neurophysiological vulnerabilities of glioblastoma. To this end, we systematically screened repurposable neuroactive drugs in glioblastoma patient surgery material using a clinically concordant and single-cell resolved platform. Profiling more than 2,500 ex vivo drug responses across 27 patients and 132 drugs identified class-diverse neuroactive drugs with potent anti-glioblastoma efficacy that were validated across model systems. Interpretable molecular machine learning of drug-target networks revealed neuroactive convergence on AP-1/BTG-driven glioblastoma suppression, enabling expanded in silico screening of more than 1 million compounds with high patient validation accuracy. Deep multimodal profiling confirmed Ca2+-driven AP-1/BTG-pathway induction as a neuro-oncological glioblastoma vulnerability, epitomized by the anti-depressant vortioxetine synergizing with current standard-of-care chemotherapies in vivo. These findings establish an actionable framework for glioblastoma treatment rooted in its neural etiology.

Antipsychotics possess anti-glioblastoma activity by disrupting lysosomal function and inhibiting oncogenic signaling by stabilizing PTEN

The repurposing of medications developed for central nervous system (CNS) disorders, possessing favorable safety profiles and blood-brain barrier permeability, represents a promising strategy for identifying new therapies to combat glioblastoma (GBM). In this study, we investigated the anti-GBM activity of specific antipsychotics and antidepressants in vitro and in vivo. Our results demonstrate that these compounds share a common mechanism of action in GBM, disrupting lysosomal function and subsequently inducing lysosomal membrane rupture and cell death. Notably, PTEN intact GBMs possess an increased sensitivity to these compounds. The inhibition of lysosomal function synergized with inhibitors targeting the EGFR-PI3K-Akt pathway, leading to an energetic and antioxidant collapse. These findings provide a foundation for the potential clinical application of CNS drugs in GBM treatment. Additionally, this work offers critical insights into the mechanisms and determinants of cytotoxicity for drugs currently undergoing clinical trials as repurposing agents for various cancers, including Fluoxetine, Sertraline, Thioridazine, Chlorpromazine, and Fluphenazine.

Overcoming Barriers in Glioblastoma-Advances in Drug Delivery Strategies

The world of cancer treatment is evolving rapidly and has improved the prospects of many cancer patients. Yet, there are still many cancers where treatment prospects have not (or hardly) improved. Glioblastoma is the most common malignant primary brain tumor, and even though it is sensitive to many chemotherapeutics when tested under laboratory conditions, its clinical prospects are still very poor. The blood-brain barrier (BBB) is considered at least partly responsible for the high failure rate of many promising treatment strategies. We describe the workings of the BBB during healthy conditions and within the glioblastoma environment. How the BBB acts as a barrier for therapeutic options is described as well as various approaches developed and tested for passing or opening the BBB, with the ultimate aim to allow access to brain tumors and improve patient perspectives.

Iloperidone and Temozolomide Synergistically Inhibit Growth, Migration and Enhance Apoptosis in Glioblastoma Cells

Glioblastoma (GBM) is a fatal astrocytic glioma with poor prognosis and treatment resistance. Repurposing potential FDA-approved drugs like anti-psychotics can address the concerns in a timely and cost-effective manner. Epidemiological studies have shown that patients with schizophrenic using anti-psychotics have a low incidence of GBM. Therefore, we aimed to investigate the therapeutic potential of atypical anti-psychotic Iloperidone (ILO) alone and in combination with Temozolomide (TMZ) against GBM. The study assessed the growth inhibitory effect of ILO, TMZ, and their combination (ILO + TMZ) on U-87MG and T-98G cell lines using an MTT assay. The drug interaction coefficient (CDI) was determined, and doses with synergistic effects were used for subsequent experiments, including migratory, invasion, and TUNEL assays. The expressions of DRD2, β-catenin, Dvl2, Twist, and Slug were assessed by RTq-PCR, whereas the β-catenin protein expression was also determined by immunocytochemistry. ILO (p < 0.05) and TMZ (p < 0.01) significantly inhibited the growth of U-87MG cells at all tested doses. The combination of 60 µM of both drugs showed synergistic activity with CDI < 1. The inhibition of migration and apoptosis was more pronounced in the case of combination treatment (p < 0.001). Inhibition of the invading cells was also found to be significant in ILO- and combination-treated groups (p < 0.001). ILO and combination treatment also significantly downregulated the expression of DRD2, while TMZ upregulated the expression (p < 0.001). The expressions of β-catenin (p < 0.001), Dvl2 (p < 0.001), Twist (p < 0.001), and Slug (p < 0.001) were also significantly downregulated in all treatment groups as compared to the vehicle control. The data suggest that ILO possesses strong growth inhibitory activity, possibly due to its effect on DRD2 and β-catenin expression and has the potential to be repurposed against GBM.

Eco-friendly synthesis of new olanzapine derivatives and evaluation of their anticancer potential

New derivatives of the known antipsychotic drug olanzapine have been obtained as potential compounds with anticancer activity in two metabolically different breast cancer cell lines: MCF-7 and triple negative MDA-MB-231. The compounds were obtained under phase transfer catalysis (PTC) in the presence of microwave irradiation (MW) or ultrasound (")))"), evaluating the effect of solvents such as dimethylformamide, water, or choline chloride/urea (natural deep eutectic solvent, NaDES). In the best option, the compounds were obtained within 2 minutes with a yield of 57-86% in MW. Two of the obtained compounds which have a naphthalimide moiety and a pentyl (7) or hexyl chain (8) show pronounced cytotoxicity. Interestingly, neither olanzapine nor desmethylolanzapine (DOLA), which was one of the substrates for the synthesis reaction, showed any significant activity in the study.

Targeting Prostate Cancer, the 'Tousled Way'

Androgen deprivation therapy (ADT) has been the mainstay of prostate cancer (PCa) treatment, with success in developing more effective inhibitors of androgen synthesis and antiandrogens in clinical practice. However, hormone deprivation and AR ablation have caused an increase in ADT-insensitive PCas associated with a poor prognosis. Resistance to ADT arises through various mechanisms, and most castration-resistant PCas still rely on the androgen axis, while others become truly androgen receptor (AR)-independent. Our research identified the human tousled-like kinase 1 (TLK1) as a crucial early mediator of PCa cell adaptation to ADT, promoting androgen-independent growth, inhibiting apoptosis, and facilitating cell motility and metastasis. Although explicit, the growing role of TLK1 biology in PCa has remained underrepresented and elusive. In this review, we aim to highlight the diverse functions of TLK1 in PCa, shed light on the molecular mechanisms underlying the transition from androgen-sensitive (AS) to an androgen-insensitive (AI) disease mediated by TLK1, and explore potential strategies to counteract this process. Targeting TLK1 and its associated signaling could prevent PCa progression to the incurable metastatic castration-resistant PCa (mCRPC) stage and provide a promising approach to treating PCa.

Longitudinal multi-omics alterations response to 8-week risperidone monotherapy: Evidence linking cortical thickness, transcriptomics and epigenetics

Background

Antipsychotic treatment-related alterations of cortical thickness (CT) and clinical symptoms have been previously corroborated, but less is known about whether the changes are driven by gene expression and epigenetic modifications.

Methods

Utilizing a prospective design, we recruited 42 treatment-naive first-episode schizophrenia patients (FESP) and 38 healthy controls. Patients were scanned by TI weighted imaging before and after 8-week risperidone monotherapy. CT estimation was automatically performed with the FreeSurfer software package. Participants' peripheral blood genomic DNA methylation (DNAm) status, quantified by using Infinium^® Human Methylation 450K BeadChip, was examined in parallel with T1 scanning. In total, CT measures from 118 subjects and genomic DNAm status from 114 subjects were finally collected. Partial least squares (PLS) regression was used to detect the spatial associations between longitudinal CT variations after treatment and cortical transcriptomic data acquired from the Allen Human Brain Atlas. Canonical correlation analysis (CCA) was then performed to identify multivariate associations between DNAm of PLS1 genes and patients' clinical improvement.

Results

We detected the significant PLS1 component (2,098 genes) related to longitudinal alterations of CT, and the PLS1 genes were significantly enriched in neurobiological processes, and dopaminergic- and cancer-related pathways. Combining Laplacian score and CCA analysis, we further linked DNAm of 33 representative genes from the 2,098 PLS1 genes with patients' reduction rate of clinical symptoms.

Conclusions

This study firstly revealed that changes of CT and clinical behaviors after treatment may be transcriptionally and epigenetically underlied. We define a "three-step" roadmap which represents a vital step toward the exploration of treatment- and treatment response-related biomarkers on the basis of multiple omics rather than a single omics type as a strategy for advancing precise care.

DRD1 and DRD4 are differentially expressed in breast tumors and breast cancer stem cells: pharmacological implications

BACKGROUND

Abnormal expression of dopamine receptors (DRs) has been described in multiple tumors, but their roles in breast cancer are inconclusive or contradictory since evidence of pro- and anti-tumoral effects have been reported. Herein, we analyzed the expression of DRs in breast cancer, especially in the subpopulation of cancer stem cells (CSCs), and evaluated the functional role of the receptors by pharmacological targeting.

METHODS

Expression of DRD1, DRD2, DRD3, DRD4 and DRD5 was investigated in human breast tumors and cancer cell lines using public databases. Correlation between gene expression and clinical outcome was studied by Kaplan-Mayer analyses. By flow cytometry, we assessed DRD1, DRD2, and DRD4 expression in cultures of MCF-7 (luminal) and MDA-MB-231 (triple-negative) cells. Using the previously reported SORE6 reporter system we examined the differential expression of DRD1, DRD2, and DRD4 in CSCs and tumor-bulk cells. The effect of pharmacological modulation of DRs on stemness and cell migration was studied by quantification of the reporter-positive fraction and wound healing assays, respectively.

RESULTS

DRD1, DRD2 and DRD4 transcripts were expressed in breast tumors. DRD4 was overexpressed compared to normal tissue and showed prognostic value. DRD1, DRD2 and DRD4 transcripts were also found in MCF-7 and MDA-MB-231 cells, but only DRD1 and DRD4 proteins were detected. DRD4 was underexpressed in CSCs compared to tumor-bulk cells, whereas DRD1 was found only in the CSCs fraction, suggesting that those receptors may have relevance in stemness control. Subtoxic concentrations of DRD1-targeting compounds did not induced significant changes in the CSCs pool. On the other hand, DRD4 inhibition by Haloperidol slightly increased the CSCs content but also reduced cell migration.

CONCLUSIONS

Pharmacological modulation of DRD1 in MCF-7 or MDA-MB-231 cells seems to be irrelevant for stemness maintenance. DRD4 reduced expression in breast CSCs or its inhibition by Haloperidol favors CSCs-pool expansion. DRD4 inhibition can also reduce cell migration, indicating that DRD4 plays different roles in stem and non-stem breast cancer cells.

Treatment of cancer with antipsychotic medications: Pushing the boundaries of schizophrenia and cancer

Over a century ago, the phenothiazine dye, methylene blue, was discovered to have both antipsychotic and anti-cancer effects. In the 20th-century, the first phenothiazine antipsychotic, chlorpromazine, was found to inhibit cancer. During the years of elucidating the pharmacology of the phenothiazines, reserpine, an antipsychotic with a long historical background, was likewise discovered to have anti-cancer properties. Research on the effects of antipsychotics on cancer continued slowly until the 21st century when efforts to repurpose antipsychotics for cancer treatment accelerated. This review examines the history of these developments, and identifies which antipsychotics might treat cancer, and which cancers might be treated by antipsychotics. The review also describes the molecular mechanisms through which antipsychotics may inhibit cancer. Although the overlap of molecular pathways between schizophrenia and cancer have been known or suspected for many years, no comprehensive review of the subject has appeared in the psychiatric literature to assess the significance of these similarities. This review fills that gap and discusses what, if any, significance the similarities have regarding the etiology of schizophrenia.

Diazepam diminishes temozolomide efficacy in the treatment of U87 glioblastoma cell line

AIMS

Many patients with glioblastoma (GBM) suffer from comorbid neurological/psychiatric disorders and, therefore, are treated with psychopharmacological agents. Diazepam (DIA) is widely adopted to treat status epilepticus, alleviate anxiety, and inhibit chemotherapy-associated delayed emesis in GBM patients. Even though temozolomide (TMZ) and DIA could be found as possible combination therapy in clinical practice, there are no reports of their combined effects in GBM. Hence, it may be of interest to investigate whether DIA enhances the antitumor efficacy of TMZ in GBM cells.

METHODS

U87 human GBM was used to examine the effects of combined TMZ and DIA on cell viability, and the oxygen consumption within the cells, in order to evaluate mitochondrial bioenergetic response upon the treatment.

RESULTS

The cooperative index showed the presence of antagonism between TMZ and DIA, which was confirmed on long-term observation. Moreover, the level of apoptosis after the TMZ treatment was significantly decreased when administered with DIA (p < 0.001). Concomitant use of TMZ and DIA increased the basal cell respiration rate, the oxidative phosphorylation rate, and maximal capacity of mitochondrial electron transport chain, as well as the activities of complexes I and II, vs. TMZ alone (p < 0.001).

CONCLUSION

Comparing our results with data reported that DIA elicits cell cycle arrest in the G0/G1 phase and favors senescence reveals that DIA diminishes TMZ efficacy in concomitant use in the treatment of GBM. However, due to its great potency to hinder GBM proliferation and metabolism, it could be considered using DIA as maintenance therapy after TMZ cycles.

Transcription Profile and Pathway Analysis of the Endocannabinoid Receptor Inverse Agonist AM630 in the Core and Infiltrative Boundary of Human Glioblastoma Cells

Background: We have previously reported that the endocannabinoid receptor inverse agonist AM630 is a potent inhibitor of isocitrade dehydrogenase-1 wild-type glioblastoma (GBM) core tumour cell proliferation. To uncover the mechanism behind the anti-tumour effects we have performed a transcriptional analysis of AM630 activity both in the tumour core cells (U87) and the invasive margin cells (GIN-8), the latter representing a better proxy of post-surgical residual disease. Results: The core and invasive margin cells exhibited markedly different gene expression profiles and only the core cells had high expression of a potential AM630 target, the CB1 receptor. Both cell types had moderate expression of the HTR2B serotonin receptor, a reported AM630 target. We found that the AM630 driven transcriptional response was substantially higher in the central cells than in the invasive margin cells, with the former driving the up regulation of immune response and the down regulation of cell cycle and metastatic pathways and correlating with transcriptional responses driven by established anti-neoplastics as well as serotonin receptor antagonists. Conclusion: Our results highlight the different gene sets involved in the core and invasive margin cell lines derived from GBM and an associated marked difference in responsiveness to AM630. Our findings identify AM630 as an anti-neoplastic drug in the context of the core cells, showing a high correlation with the activity of known antiproliferative drugs. However, we reveal a key set of similarities between the two cell lines that may inform therapeutic intervention.

From GWAS to drug screening: repurposing antipsychotics for glioblastoma

BACKGROUND

Glioblastoma is currently an incurable cancer. Genome-wide association studies have demonstrated that 41 genetic variants are associated with glioblastoma and may provide an option for drug development.

METHODS

We investigated FDA-approved antipsychotics for their potential treatment of glioblastoma based on genome-wide association studies data using a 'pathway/gene-set analysis' approach.

RESULTS

The in-silico screening led to the discovery of 12 candidate drugs. DepMap portal revealed that 42 glioma cell lines show higher sensitivities to 12 candidate drugs than to Temozolomide, the current standard treatment for glioblastoma.

CONCLUSION

In particular, cell lines showed significantly higher sensitivities to Norcyclobenzaprine and Protriptyline which were predicted to bind targets to disrupt a certain molecular function such as DNA repair, response to hormones, or DNA-templated transcription, and may lead to an effect on survival-related pathways including cell cycle arrest, response to ER stress, glucose transport, and regulation of autophagy. However, it is recommended that their mechanism of action and efficacy are further determined.

Drug Repurposing for Glioblastoma and Current Advances in Drug Delivery-A Comprehensive Review of the Literature

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults with an extremely poor prognosis. There is a dire need to develop effective therapeutics to overcome the intrinsic and acquired resistance of GBM to current therapies. The process of developing novel anti-neoplastic drugs from bench to bedside can incur significant time and cost implications. Drug repurposing may help overcome that obstacle. A wide range of drugs that are already approved for clinical use for the treatment of other diseases have been found to target GBM-associated signaling pathways and are being repurposed for the treatment of GBM. While many of these drugs are undergoing pre-clinical testing, others are in the clinical trial phase. Since GBM stem cells (GSCs) have been found to be a main source of tumor recurrence after surgery, recent studies have also investigated whether repurposed drugs that target these pathways can be used to counteract tumor recurrence. While several repurposed drugs have shown significant efficacy against GBM cell lines, the blood–brain barrier (BBB) can limit the ability of many of these drugs to reach intratumoral therapeutic concentrations. Localized intracranial delivery may help to achieve therapeutic drug concentration at the site of tumor resection while simultaneously minimizing toxicity and side effects. These strategies can be considered while repurposing drugs for GBM.

Repurposing of Anticancer Stem Cell Drugs in Brain Tumors

Brain tumors in adults may be infrequent when compared with other cancer etiologies, but they remain one of the deadliest with bleak survival rates. Current treatment modalities encompass surgical resection, chemotherapy, and radiotherapy. However, increasing resistance rates are being witnessed, and this has been attributed, in part, to cancer stem cells (CSCs). CSCs are a subpopulation of cancer cells that reside within the tumor bulk and have the capacity for self-renewal and can differentiate and proliferate into multiple cell lineages. Studying those CSCs enables an increasing understanding of carcinogenesis, and targeting CSCs may overcome existing treatment resistance. One approach to weaponize new drugs is to target these CSCs through drug repurposing which entails using drugs, which are Food and Drug Administration-approved and safe for one defined disease, for a new indication. This approach serves to save both time and money that would otherwise be spent in designing a totally new therapy. In this review, we will illustrate drug repurposing strategies that have been used in brain tumors and then further elaborate on how these approaches, specifically those that target the resident CSCs, can help take the field of drug repurposing to a new level.

Prochlorperazine enhances radiosensitivity of non-small cell lung carcinoma by stabilizing GDP-bound mutant KRAS conformation

Lung cancer is considered as leading cancer with the highest mortality. The KRAS-oncogenic mutations are dominant in lung carcinoma leading to poor prognosis and radioresistance, which is a major impediment to radiotherapy. Thus, KRAS mutant inhibitors that synergistically sensitize tumours to radiation are urgently needed. In pursuance of the search for a novel radiosensitizer, high-throughput screening of FDA-approved drugs was performed at active site of K-Ras. Prochlorperazine (PCZ), an antipsychotic drug, showed good binding affinity with KRAS-mutant proteins. PCZ binds to the GTP-binding pocket of KRAS-mutant protein and inhibits its constitutive activation by stabilizing the GDP-bound conformation of K-Ras mutants by 9 kcal/mol compared to WT. PCZ alongwith radiation decreased the clonogenic survival of KRAS-mutant NSCLC but not KRAS-WT cells. The combination treatment activates p-ATM, p53, and p21 proteins, leading to cell cycle arrest. PCZ with increasing radiation caused a linear increase in γH2AX foci, suggesting enhanced DSBs-associated apoptosis in radioresistant A549 cells. Pharmacokinetics study showed C_max = 526 ng/ml at 30min, 4.6h half-life in plasma, and highest accumulation in tumours. PCZ and 10Gy irradiation synergistically radiosensitize mice xenografts via downregulation of Ras/Raf/MEK/ERK pathway. Our efforts have led to the discovery of PCZ as a lead compound. In preclinical analyses, treatment with PCZ alone and in combination with radiation led to regression of KRAS^-G12S tumours.

Autophagy activation, lipotoxicity and lysosomal membrane permeabilization synergize to promote pimozide- and loperamide-induced glioma cell death

Increasing evidence suggests that induction of lethal macroautophagy/autophagy carries potential significance for the treatment of glioblastoma (GBM). In continuation of previous work, we demonstrate that pimozide and loperamide trigger an ATG5- and ATG7 (autophagy related 5 and 7)-dependent type of cell death that is significantly reduced with cathepsin inhibitors and the lipid reactive oxygen species (ROS) scavenger α-tocopherol in MZ-54 GBM cells. Global proteomic analysis after treatment with both drugs also revealed an increase of proteins related to lipid and cholesterol metabolic processes. These changes were accompanied by a massive accumulation of cholesterol and other lipids in the lysosomal compartment, indicative of impaired lipid transport/degradation. In line with these observations, pimozide and loperamide treatment were associated with a pronounced increase of bioactive sphingolipids including ceramides, glucosylceramides and sphingoid bases measured by targeted lipidomic analysis. Furthermore, pimozide and loperamide inhibited the activity of SMPD1/ASM (sphingomyelin phosphodiesterase 1) and promoted induction of lysosomal membrane permeabilization (LMP), as well as release of CTSB (cathepsin B) into the cytosol in MZ-54 wild-type (WT) cells. Whereas LMP and cell death were significantly attenuated in ATG5 and ATG7 knockout (KO) cells, both events were enhanced by depletion of the lysophagy receptor VCP (valosin containing protein), supporting a pro-survival function of lysophagy under these conditions. Collectively, our data suggest that pimozide and loperamide-driven autophagy and lipotoxicity synergize to induce LMP and cell death. The results also support the notion that simultaneous overactivation of autophagy and induction of LMP represents a promising approach for the treatment of GBM.Abbreviations: ACD: autophagic cell death; AKT1: AKT serine/threonine kinase 1; ATG5: autophagy related 5; ATG7: autophagy related 7; ATG14: autophagy related 14; CERS1: ceramide synthase 1; CTSB: cathepsin B; CYBB/NOX2: cytochrome b-245 beta chain; ER: endoplasmatic reticulum; FBS: fetal bovine serum; GBM: glioblastoma; GO: gene ontology; HTR7/5-HT7: 5-hydroxytryptamine receptor 7; KD: knockdown; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LAP: LC3-associated phagocytosis; LMP: lysosomal membrane permeabilization; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MTOR: mechanistic target of rapamycin kinase; RB1CC1: RB1 inducible coiled-coil 1; ROS: reactive oxygen species; RPS6: ribosomal protein S6; SMPD1/ASM: sphingomyelin phosphodiesterase 1; VCP/p97: valosin containing protein; WT: wild-type.

miRNAs in the Expression Regulation of Dopamine-Related Genes and Proteins in Endometrial Cancer

Disruption of the dopaminergic system leads to many diseases, including cancer. Dopamine and its receptors are involved in the regulation of proliferation, cell death, invasion, and migration. Better understanding of the mechanisms involved in these processes could reveal new molecular markers and therapeutic targets. The aim of this study was to determine the expression profile of dopamine-related genes and proteins in endometrial cancer and to assess whether miRNAs are involved in its regulation. Sixty women were recruited for the study: 30 with endometrial cancer and 30 without cancer. The expression profiles of dopamine-related genes were determined in endometrial tissue samples using microarrays and qRT-PCR. Then, protein concentration was determined with the ELISA test. In the last step, miRNA detection was performed using microarrays. The matching of miRNAs to the studied genes was carried out using the TargetScan tool. The analysis showed DRD2 and DRD3 overexpression, with a reduction in DRD5 expression, which could be due to miR-15a-5p, miR-141-3p, miR-4640-5p, and miR-221-5p activity. High levels of OPRK1 and CXCL12, related to the activity of miR-124-3p.1 and miR-135b-5p, have also been reported. Low COMT expression was probably not associated with miRNA regulation in endometrial cancer.

Pharmacological characterization of the imipridone anti-cancer drug ONC201 reveals a negative allosteric mechanism of action at the D2 dopamine receptor

ONC201 is a first-in-class imipridone compound that is in clinical trials for the treatment of high-grade gliomas and other advanced cancers. Recent studies identified that ONC201 antagonizes D2-like dopamine receptors at therapeutically relevant concentrations. In the current study, characterization of ONC201 using radioligand binding and multiple functional assays revealed that it was a full antagonist of the D2 and D3 receptors (D2R and D3R) with low micromolar potencies, similar to its potency for anti-proliferative effects. Curve-shift experiments using D2R-mediated b-arrestin recruitment and cAMP assays revealed that ONC201 exhibited a mixed form of antagonism. An operational model of allostery was used to analyze these data, which suggested that the predominant modulatory effect of ONC201 was on dopamine efficacy with little to no effect on dopamine affinity. To investigate how ONC201 binds to the D2R, we employed scanning mutagenesis coupled with a D2R-mediated calcium efflux assay. Eight residues were identified as being important for ONC201's functional antagonism of the D2R. Mutation of these residues followed by assessing ONC201 antagonism in multiple signaling assays highlighted specific residues involved in ONC201 binding. Together with computational modeling and simulation studies, our results suggest that ONC201 interacts with the D2R in a bitopic manner where the imipridone core of the molecule protrudes into the orthosteric binding site, but does not compete with dopamine, whereas a secondary phenyl ring engages an allosteric binding pocket that may be associated with negative modulation of receptor activity. Significance Statement ONC201 is a novel antagonist of the D2 dopamine receptor with demonstrated efficacy in the treatment of various cancers, especially high-grade glioma. In this study, we demonstrate that it antagonizes the D2 receptor with novel bitopic and negative allosteric mechanisms of action, which may explain its high selectivity and some of its clinical anti-cancer properties that are distinct from other D2 receptor antagonists widely used for the treatment of schizophrenia and other neuropsychiatric disorders.

G-protein-coupled receptors as therapeutic targets for glioblastoma

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumour in adults. Treatments include surgical resection, radiotherapy, and chemotherapy. Despite this, the prognosis remains poor, with an impacted quality of life during treatment coupled with brain tumour recurrence; thus, new treatments are desperately needed. In this review, we focus on recent advances in G-protein-coupled receptor (GPCR) targets. To date, the most promising targets are the chemokine, cannabinoid, and dopamine receptors, but future work should further examine the melanocortin receptor-4 (MC4R), adhesion, lysophosphatidic acid (LPA) and smoothened (Smo) receptors to initiate new drug-screening strategies and targeted delivery of safe and effective GBM therapies.

Depression and anxiety in recurrent giant cell tumor of bone

Giant cell tumor of bone (GCTB) is a benign neoplasia more frequently encountered in young females. The pathogenic and evolutionary dynamics of the disease is strongly influenced by the presence of depression and cellular mechanisms, especially proinflammatory and immune. Although it is not a malignant tumor, it is often recurrent, which determines a high level of depression, anxiety, and fear of the patients. Cytokine mechanisms, especially through increased tumor necrosis factor alpha (TNFα) and interleukin-6 (IL-6), as well as the involvement of the receptor activator of nuclear factor-kappa B (RANK)–RANK ligand (RANK-L) system, can be correlated with the risk of malignancy. Unfavorable evolution is associated with persistent pain, difficulties of movement and body dysmorphic symptoms. The diagnosis is based mainly on histopathological (HP) assessment. The patients can be treated with pharmacological agents (Denosumab), surgery with tumor excision, reconstruction or osteosynthesis, and radiotherapy. Patients with GCTB require HP and imaging evaluations, especially of relapses, to detect the risk of metastasis or malignancy, simultaneously with psychological and psychiatric monitoring to detect depression, addictive behaviors, and suicide risk. It is necessary to evaluate in a multidisciplinary team to avoid unfavorable oncological and psychiatric developments. Through its clinical, HP, and therapeutic features, GCTB has multiple connections with the psychological and psychopathological dimension.

Novel dopamine receptor 3 antagonists inhibit the growth of primary and temozolomide resistant glioblastoma cells

Treatment for the lethal primary adult brain tumor glioblastoma (GBM) includes the chemotherapy temozolomide (TMZ), but TMZ resistance is common and correlates with promoter methylation of the DNA repair enzyme O-6-methylguanine-DNA methyltransferase (MGMT). To improve treatment of GBMs, including those resistant to TMZ, we explored the potential of targeting dopamine receptor signaling. We found that dopamine receptor 3 (DRD3) is expressed in GBM and is also a previously unexplored target for therapy. We identified novel antagonists of DRD3 that decreased the growth of GBM xenograft-derived neurosphere cultures with minimal toxicity against human astrocytes and/or induced pluripotent stem cell-derived neurons. Among a set of DRD3 antagonists, we identified two compounds, SRI-21979 and SRI-30052, that were brain penetrant and displayed a favorable therapeutic window analysis of The Cancer Genome Atlas data demonstrated that higher levels of DRD3 (but not DRD2 or DRD4) were associated with worse prognosis in primary, MGMT unmethylated tumors. These data suggested that DRD3 antagonists may remain efficacious in TMZ-resistant GBMs. Indeed, SRI-21979, but not haloperidol, significantly reduced the growth of TMZ-resistant GBM cells. Together our data suggest that DRD3 antagonist-based therapies may provide a novel therapeutic option for the treatment of GBM.

Analysis of the cytotoxic effects, cellular uptake and cellular distribution of paclitaxel-loaded nanoparticles in glioblastoma cells in vitro

Glioblastoma is the most common and aggressive type of brain tumor. Although treatments for glioblastoma have been improved recently, patients still suffer from local recurrence in addition to poor prognosis. Previous studies have indicated that the efficacy of chemotherapeutic or bioactive agents is severely compromised by the blood-brain barrier and the inherent drug resistance of glioblastoma. The present study developed a delivery system to improve the efficiency of delivering therapeutic agents into glioblastoma cells. The anticancer drug paclitaxel (PTX) was packed into nanoparticles that were composed of amphiphilic poly (γ-glutamic-acid-maleimide-co-L-lactide)-1,2-dipalmitoylsn-glycero-3-phosphoethanolaminecopolymer conjugated with targeting moiety transferrin (Tf). The Tf nanoparticles (Tf-NPs) may enter glioblastoma cells via transferrin receptor-mediated endocytosis. MTT assay and flow cytometry were used to explore the cytotoxic effects, cellular uptake and cellular distribution of paclitaxel-loaded nanoparticles. The results indicated that both PTX and PTX-Tf-NPs inhibited the viability of rat glioblastoma C6 cells in a dose-dependent manner, but the PTX-Tf-NPs exhibited a greater inhibitory effect compared with PTX, even at higher concentrations (0.4, 2 and 10 µg/ml). However, both PTX and PTX-Tf-NPs exhibited a reduced inhibitory effect on the viability of mouse hippocampal neuronal HT22 cells compared with that on C6 cells. Additionally, in contrast to PTX alone, PTX-Tf-NPs treatment of C6 cells at lower concentrations (0.0032, 0.0160 and 0.0800 µg/ml) induced increased G₂/M arrest, although this difference did not occur at a higher drug concentration (0.4 µg/ml). It was observed that FITC-labeled PTX-Tf-NPs were endocytosed by C6 cells within 4 h. Furthermore, FITC-labeled PTX-Tf-NPs or Tf-NPs co-localized with a lysosomal tracker, Lysotracker Red DND-99. These results of the present study indicated that Tf-NPs enhanced the cytotoxicity of PTX in glioblastoma C6 cells, suggesting that PTX-Tf-NPs should be further explored in animal models of glioblastoma.

Dopamine Receptors in Cancer: Are They Valid Therapeutic Targets?

The dopamine receptors (DRs) family includes 5 members with differences in signal transduction and ligand affinity. Abnormal DRs expression has been correlated multiple tumors with their clinical outcome. Thus, it has been proposed that DRs-targeting drugs-developed for other diseases as schizophrenia or Parkinson's disease-could be helpful in managing neoplastic diseases. In this review, we discuss the role of DRs and the effects of DRs-targeting in tumor progression and cancer cell biology using multiple high-prevalence neoplasms as examples. The evidence shows that DRs are valid therapeutic targets for certain receptor/disease combinations, but the data are inconclusive or contradictory for others. In either case, further studies are required to define the precise role of DRs in tumor progression and propose better therapeutic strategies for their targeting.

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.

Generation of Phenothiazine with Potent Anti-TLK1 Activity for Prostate Cancer Therapy

Through in vitro kinase assays and docking studies, we report the synthesis and biological evaluation of a phenothiazine analog J54 with potent TLK1 inhibitory activity for prostate cancer (PCa) therapy. Most PCa deaths result from progressive failure in standard androgen deprivation therapy (ADT), leading to metastatic castration-resistant PCa. Treatments that can suppress the conversion to mCRPC have high potential to be rapidly implemented in the clinics. ADT results in increased expression of TLK1B, a key kinase upstream of NEK1 and ATR and mediating the DNA damage response that typically results in temporary cell-cycle arrest of androgen-responsive PCa cells, whereas its abrogation leads to apoptosis. We studied J54 as a potent inhibitor of this axis and as a mediator of apoptosis in vitro and in LNCaP xenografts, which has potential for clinical investigation in combination with ADT. J54 has low affinity for the dopamine receptor in modeling and competition studies and weak detrimental behavioral effects in mice and C. elegans.

Drug rechanneling: A novel paradigm for cancer treatment

Cancer continues to be one of the leading contributors towards global disease burden. According to NIH, cancer incidence rate per year will increase to 23.6 million by 2030. Even though cancer continues to be a major proportion of the disease burden worldwide, it has the lowest clinical trial success rate amongst other diseases. Hence, there is an unmet need for novel, affordable and effective anti-neoplastic medications. As a result, a growing interest has sparkled amongst researchers towards drug repurposing. Drug repurposing follows the principle of polypharmacology, which states, "any drug with multiple targets or off targets can present several modes of action". Drug repurposing also known as drug rechanneling, or drug repositioning is an economic and reliable approach that identifies new disease treatment of already approved drugs. Repurposing guarantees expedited access of drugs to the patients as these drugs are already FDA approved and their safety and toxicity profile is completely established. Epidemiological studies have identified the decreased occurrence of oncological or non-oncological conditions in patients undergoing treatment with FDA approved drugs. Data from multiple experimental studies and clinical observations have depicted that several non-neoplastic drugs have potential anticancer activity. In this review, we have summarized the potential anti-cancer effects of anti-psychotic, anti-malarial, anti-viral and anti-emetic drugs with a brief overview on their mechanism and pathways in different cancer types. This review highlights promising evidences for the repurposing of drugs in oncology.

Receptor tyrosine kinase targeting in glioblastoma: performance, limitations and future approaches

From all central nervous system tumors, gliomas are the most common. Nowadays, researchers are looking for more efficient treatments for these tumors, as well as ways for early diagnosis. Receptor tyrosine kinases (RTKs) are major targets for oncology and the development of small-molecule RTK inhibitors has been proven successful in cancer treatment. Mutations or aberrant activation of the RTKs and their intracellular signaling pathways are linked to several malignant diseases, including glioblastoma. The progress in the understanding of malignant glioma evolution has led to RTK targeted therapies with high capacity to improve the therapeutic response while reducing toxicity. In this review, we present the most important RTKs (i.e. EGFR, IGFR, PDGFR and VEGFR) currently used for developing cancer therapeutics together with the potential of RTK-related drugs in glioblastoma treatment. Also, we focus on some therapeutic agents that are currently at different stages of research or even in clinical phases and proved to be suitable as re-purposing candidates for glioblastoma treatment.

New drugs are not enough‑drug repositioning in oncology: An update

Drug repositioning refers to the concept of discovering novel clinical benefits of drugs that are already known for use treating other diseases. The advantages of this are that several important drug characteristics are already established (including efficacy, pharmacokinetics, pharmacodynamics and toxicity), making the process of research for a putative drug quicker and less costly. Drug repositioning in oncology has received extensive focus. The present review summarizes the most prominent examples of drug repositioning for the treatment of cancer, taking into consideration their primary use, proposed anticancer mechanisms and current development status.

Current state and future perspective of drug repurposing in malignant glioma

Malignant gliomas are still extremely difficult to treat because complete surgical resection is biologically not feasible due to the invasive nature of these diseases and the proximity of tumors to functionally sensitive areas. Moreover, adjuvant therapies are facing a strong therapeutic resistance since the central nervous system is a highly protected environment and the tumor cells display a vast intra-tumoral genetic and epigenetic variation. As a consequence, new therapeutics are urgently needed but the process of developing novel compounds that finally reach clinical application is highly time-consuming and expensive. Drug repurposing is an approach to facilitate and accelerate the discovery of new cancer treatments. In malignant glioma, like in other cancers, pre-existing physiological pathways that regulate cell growth, cell death or cell migration are dysregulated causing malignant transformation. A wide variety of drugs are clinically used to treat non-cancerous diseases interfering with these malignancy-associated pathways. Repurposed drugs have key advantages: They already have approval for clinical use by national regulatory authorities. Moreover, they are for the most part inexpensive and their side effect and safety profiles are well characterized. In this work, we provide an overview on current repurposing strategies for the treatment of malignant glioma.

Surprising Anticancer Activities of Psychiatric Medications: Old Drugs Offer New Hope for Patients With Brain Cancer

Despite decades of research and major efforts, malignant brain tumors remain among the deadliest of all cancers. Recently, an increasing number of psychiatric drugs has been proven to possess suppressing activities against brain tumors, and rapid progress has been made in understanding the potential mechanisms of action of these drugs. In particular, the traditional mood stabilizer valproic acid, the widely used antidepressants fluoxetine and escitalopram oxalate, and the atypical psychiatric drug aripiprazole have demonstrated promise for application in brain tumor treatment strategies through multiple lines of laboratory, preclinical, and clinical evidence. The unexpected discovery of the anticancer properties of these drugs has ignited interest in the repurposing of other psychiatric drugs to combat brain cancer. In this review, we synthesize recent progress in understanding the potential molecular mechanisms underlying the brain cancer-killing activities of representative psychiatric drugs. We also identify key limitations in the repurposing of these medications that must be overcome to enhance our ability to successfully prevent and treat brain cancer, especially in the most vulnerable groups of patients, such as children and adolescents, pregnant women, and those with unfavorable genetic variants. Moreover, we propose perspectives that may guide future research and provide long-awaited new hope to patients with brain cancer and their families.

High-throughput screening discovers antifibrotic properties of haloperidol by hindering myofibroblast activation

Fibrosis is a hallmark in the pathogenesis of various diseases, with very limited therapeutic solutions. A key event in the fibrotic process is the expression of contractile proteins, including α-smooth muscle actin (αSMA) by fibroblasts, which become myofibroblasts. Here, we report the results of a high-throughput screening of a library of approved drugs that led to the discovery of haloperidol, a common antipsychotic drug, as a potent inhibitor of myofibroblast activation. We show that haloperidol exerts its antifibrotic effect on primary murine and human fibroblasts by binding to sigma receptor 1, independent from the canonical transforming growth factor-β signaling pathway. Its mechanism of action involves the modulation of intracellular calcium, with moderate induction of endoplasmic reticulum stress response, which in turn abrogates Notch1 signaling and the consequent expression of its targets, including αSMA. Importantly, haloperidol also reduced the fibrotic burden in 3 different animal models of lung, cardiac, and tumor-associated fibrosis, thus supporting the repurposing of this drug for the treatment of fibrotic conditions.

The tumor suppressor FOXO3a mediates the response to EGFR inhibition in glioblastoma cells

PURPOSE

Although EGFR activation is a hallmark of glioblastoma (GBM), anti-EGFR therapy has so far not yielded the desired effects. Targeting PI3K/Akt has been proposed as a strategy to increase the cellular sensitivity to EGFR inhibitors. Here we evaluated the contribution of FOXO3a, a key Akt target, in the response of GBM cells to EGFR inhibition.

METHODS

FOXO3a activation was assessed by immunofluorescence and gene reporter assays, and by evaluating target gene expression using Western blotting and qRT-PCR. Cellular effects were evaluated using cell viability and apoptosis assays, i.e., Annexin V/PI staining and caspase 3/7 activity measurements. Drug synergism was evaluated by performing isobolographic analyses. Gene silencing experiments were performed using stable shRNA transfections.

RESULTS

We found that EGFR inhibition in GBM cells led to FOXO3a activation and to transcriptional modulation of its key targets, including repression of the oncogene FOXM1. In addition, we found that specific FOXO3a activation recapitulated the molecular effects of EGFR inhibition, and that the FOXO3a activator trifluoperazine, a FDA-approved antipsychotic agent, reduced GBM cell growth. Subsequent isobolographic analyses of combination experiments indicated that trifluoperazine and erlotinib cooperated synergistically and that their concomitant treatment induced a robust activation of FOXO3a, leading to apoptosis in GBM cells. Using gene silencing, we found that FOXO3a is essential for the response of GBM cells to EGFR inhibition.

CONCLUSIONS

Our data indicate that FOXO3a activation is a crucial event in the response of GBM cells to EGFR inhibition, suggesting that FOXO3a may serve as an actionable therapeutic target that can be modulated using FDA-approved drugs.

Targeting the TLK1/NEK1 DDR axis with Thioridazine suppresses outgrowth of androgen independent prostate tumors

Standard therapy for advanced Prostate Cancer (PCa) consists of antiandrogens, which provide respite from disease progression, but ultimately fail resulting in the incurable phase of the disease: mCRPC. Targeting PCa cells before their progression to mCRPC would greatly improve the outcome. Combination therapy targeting the DNA Damage Response (DDR) has been limited by general toxicity, and a goal of clinical trials is how to target the DDR more specifically. We now show that androgen deprivation therapy (ADT) of LNCaP cells results in increased expression of TLK1B, a key kinase upstream of NEK1 and ATR and mediating the DDR that typically results in a temporary cell cycle arrest of androgen responsive PCa cells. Following DNA damage, addition of the TLK specific inhibitor, thioridazine (THD), impairs ATR and Chk1 activation, establishing the existence of a ADT > TLK1 > NEK1 > ATR > Chk1, DDR pathway, while its abrogation leads to apoptosis. Treatment with THD suppressed the outgrowth of androgen‐independent (AI) colonies of LNCaP and TRAMP‐C2 cells cultured with bicalutamide. Moreover, THD significantly inhibited the growth of several PCa cells in vitro (including AI lines). Administration of THD or bicalutamide was not effective at inhibiting long‐term tumor growth of LNCaP xenografts. In contrast, combination therapy remarkably inhibited tumor growth via bypass of the DDR. Moreover, xenografts of LNCaP cells overexpressing a NEK1‐T141A mutant were durably suppressed with bicalutamide. Collectively, these results suggest that targeting the TLK1/NEK1 axis might be a novel therapy for PCa in combination with standard of care (ADT).

What's new?

Standard therapy for advanced Prostate Cancer (PCa) consists of anti‐androgens, which only provide temporary respite from disease progression to metastatic castrate‐resistant prostate cancer (mCRPC). Here, the authors show in the LNCaP cell model that the increased expression with ADT of TLK1B, a prosurvival checkpoint pathway that is enacted before conversion to androgen‐independent growth, offers a unique target for attacking more specifically PCa cells before their conversion to CRPC. Moreover, they suggest to re‐purpose thioridazine or other phenothiazine antipsychotic drugs as inhibitors of the TLK1 > Nek1 > ATR > Chk1 DNA Damage Response (DDR) axis for the early treatment of advanced PCa still responsive to ADT.

The Antitumor Activity of a Lead Thioxanthone is Associated with Alterations in Cholesterol Localization

The search for novel anticancer small molecules and strategies remains a challenge. Our previous studies have identified TXA1 (1-{[2-(diethylamino)ethyl]amino}-4-propoxy-9H- thioxanthen-9-one) as a hit compound, with in vitro antitumor potential by modulating autophagy and apoptosis in human tumor cell lines. In the present study, the mechanism of action and antitumor potential of the soluble salt of this molecule (TXA1.HCl) was further investigated using in vitro and mouse xenograft tumor models of NSCLC. Our results showed that TXA1.HCl affected steroid biosynthesis, increased RagD expression, and caused abnormal cellular cholesterol localization. In addition, TXA1.HCl treatment presented no toxicity to nude mice and significantly reduced the growth of human NSCLC cells xenografts in mice. Overall, this work provides new insights into the mechanism of action of TXA1, which may be relevant for the development of anticancer therapeutic strategies, which target cholesterol transport.

Antiproliferative activities of the second-generation antipsychotic drug sertindole against breast cancers with a potential application for treatment of breast-to-brain metastases

Epidemiological observations have shown that schizophrenia patients after long-term drug treatment exhibited reduced tumor incidences. The potential anticancer effects of antipsychotic drugs are subsequently demonstrated. These drugs are of great interest as agents against untreatable brain metastases because of their ability to traverse the blood-brain barrier (BBB). Most drugs tested thus far are the first-generation antipsychotics (FGAs). But their clinical application may be limited due to high risks of deaths in elderly patients. There is an urgent need to find additional BBB-traversing anticancer agents with lower risks of deaths. In this work, we investigated antitumor activities of eight second-generation-antipsychotic (SGA) drugs, since they exhibit lower mortality rates than FGAs. We discovered that sertindole showed broad antiproliferative activities against seven cancer types including 29 cell-lines and exhibited potent effects toward breast cancer cell-lines, with half maximal concentration to inhibit proliferation by 50% (IC₅₀) as low as 800 nM. We further found that sertindole caused cell death through autophagy-associated apoptosis and its directly-binding inhibition of 5-HT6 involved in this process. In xenotransplant mice, sertindole administration approaching maximal therapeutic dose attenuated breast-tumor growth by 22.7%. Therefore, our study reveals promising anticancer potentials of sertindole against breast cancers, with probable applications for breast-to-brain metastases.

Developments in Blood-Brain Barrier Penetrance and Drug Repurposing for Improved Treatment of Glioblastoma

Glioblastoma (GBM) is one of the most common, deadly, and difficult-to-treat adult brain tumors. Surgical removal of the tumor, followed by radiotherapy (RT) and temozolomide (TMZ) administration, is the current treatment modality, but this regimen only modestly improves overall patient survival. Invasion of cells into the surrounding healthy brain tissue prevents complete surgical resection and complicates treatment strategies with the goal of preserving neurological function. Despite significant efforts to increase our understanding of GBM, there have been relatively few therapeutic advances since 2005 and even fewer treatments designed to effectively treat recurrent tumors that are resistant to therapy. Thus, while there is a pressing need to move new treatments into the clinic, emerging evidence suggests that key features unique to GBM location and biology, the blood-brain barrier (BBB) and intratumoral molecular heterogeneity, respectively, stand as critical unresolved hurdles to effective therapy. Notably, genomic analyses of GBM tissues has led to the identification of numerous gene alterations that govern cell growth, invasion and survival signaling pathways; however, the drugs that show pre-clinical potential against signaling pathways mediated by these gene alterations cannot achieve effective concentrations at the tumor site. As a result, identifying BBB-penetrating drugs and utilizing new and safer methods to enhance drug delivery past the BBB has become an area of intensive research. Repurposing and combining FDA-approved drugs with evidence of penetration into the central nervous system (CNS) has also seen new interest for the treatment of both primary and recurrent GBM. In this review, we discuss emerging methods to strategically enhance drug delivery to GBM and repurpose currently-approved and previously-studied drugs using rational combination strategies.

The nervous system: a new target in the fight against cancer

During cancer progression, tumor cells interact with the neighboring environment, including neuronal tissue. The important influence of the nervous system on growth and metastasis of cancer is now widely accepted. As such, using medications that traditionally target the nervous system may be an avenue toward treating cancer. The focus of this review is to detail how several classes of medications, traditionally used to treat nervous system disorders, impact cancer. Specifically, we review the preclinical and clinical evidence that support the use of anti-β-adrenergic, anticholinergic, antipsychotic, and antidepressant medications to treat some cancers. In addition, we discuss the use of ablative modalities, such as physical and chemical denervation, to treat cancer or protect against cancer development. Using the medications that target the nervous system to treat cancer is a promising addition to an existing therapy or an alternative treatment strategy. Furthermore, rapidly expanding basic science research in this area will likely yield novel cancer therapies that work by targeting the nervous system.

Potent effect of the MDM2 inhibitor AMG232 on suppression of glioblastoma stem cells

Testing new ways to identify untapped opportunities for glioblastoma therapies remains highly significant. Amplification and overexpression of MDM2 gene is frequent in glioblastoma and disrupting the MDM2-p53 interaction is a promising strategy to treat the cancer. RG7112 is the first-in class inhibitor and recently discovered AMG232 is the most potent MDM2 inhibitor known to date. Here, we compared the effects of these two clinical MDM2 inhibitors in six glioblastoma cell lines and ten patient-derived glioblastoma stem cells. Targeted sequencing of the TP53, MDM2 genes and whole transcriptome analysis were conducted to verify genetic status associated with sensitivity and resistance to the drugs. Although TP53 wild-type glioblastoma cell lines are similarly sensitive to AMG232 and RG7112, we found that four TP53 wild-type out of ten patient-derived glioblastoma cells are much more sensitive to AMG232 than RG7112 (average IC₅₀ of 76 nM vs. 720 nM). Among these, 464T stem cells containing MDM2 gene amplification were most sensitive to AMG232 with IC₅₀ of 5.3 nM. Moreover, AMG232 exhibited higher selectivity against p53 wild-type cells over p53 mutant stem cells compared to RG7112 (average selectivity of 512-fold vs. 16.5-fold). Importantly, we also found that AMG232 is highly efficacious in three-dimensional (3D) tumor spheroids growth and effectively inhibits the stemness-related factors, Nestin and ZEB1. Our data provide new evidence that glioblastoma stem cells have high susceptibility to AMG232 suggesting the potential clinical implications of MDM2 inhibition for glioblastoma treatment. These will facilitate additional preclinical and clinical studies evaluating MDM2 inhibitors in glioblastoma and direct further efforts towards developing better MDM2-targeted therapeutics.

Repurposing drugs for glioblastoma: From bench to bedside

Glioblastoma multiforme is the most common, aggressive and lethal type of brain tumor. It is a stage IV cancer disease with a poor prognosis, as the current therapeutic options (surgery, radiotherapy and chemotherapy) are not able to eradicate tumor cells. The approach to treat glioblastoma has not suffered major changes over the last decade and temozolomide (TMZ) remains the mainstay for chemotherapy. However, resistance mechanisms to TMZ and other chemotherapeutic agents are becoming more frequent. The lack of effective options is a reality that may be counterbalanced by repositioning known and commonly used drugs for other diseases. This approach takes into consideration the available pharmacokinetic, pharmacodynamic, toxicity and safety data, and allows a much faster and less expensive drug and product development process. In this review, an extensive literature search is conducted aiming to list drugs with repurposing usage, based on their preferential damage in glioblastoma cells through various mechanisms. Some of these drugs have already entered clinical trials, exhibiting favorable outcomes, which sparks their potential application in glioblastoma treatment.

Drug Repositioning in Glioblastoma: A Pathway Perspective

Glioblastoma multiforme (GBM) is the most malignant primary adult brain tumor. The current standard of care is surgical resection, radiation, and chemotherapy treatment, which extends life in most cases. Unfortunately, tumor recurrence is nearly universal and patients with recurrent glioblastoma typically survive <1 year. Therefore, new therapies and therapeutic combinations need to be developed that can be quickly approved for use in patients. However, in order to gain approval, therapies need to be safe as well as effective. One possible means of attaining rapid approval is repurposing FDA approved compounds for GBM therapy. However, candidate compounds must be able to penetrate the blood-brain barrier (BBB) and therefore a selection process has to be implemented to identify such compounds that can eliminate GBM tumor expansion. We review here psychiatric and non-psychiatric compounds that may be effective in GBM, as well as potential drugs targeting cell death pathways. We also discuss the potential of data-driven computational approaches to identify compounds that induce cell death in GBM cells, enabled by large reference databases such as the Library of Integrated Network Cell Signatures (LINCS). Finally, we argue that identifying pathways dysregulated in GBM in a patient specific manner is essential for effective repurposing in GBM and other gliomas.

Tumor progression: the neuronal input

One of the challenges of cancer is its heterogeneity and rapid capacity to adapt. Notwithstanding significant progress in the last decades in genomics and precision medicine, new molecular targets and therapies appear highly necessary. One way to approach this complex problem is to consider cancer in the context of its cellular and molecular microenvironment, which includes nerves. The peripheral nerves, the topic of this review, modulate the biological behavior of the cancer cells and influence tumor progression, including the events related to the metastatic spread of the disease. This mechanism involves the release of neurotransmitters directly into the microenvironment and the activation of the corresponding membrane receptors. While this fact appears to complicate further the molecular landscape of cancer, the neurotransmitters are highly investigated molecules, and often are already targeted by well-developed drugs, a fact that can help finding new therapies at a fraction of the cost and time needed for new medicines (through the so-called drug repurposing). Moreover, the modulation of tumor progression by neurotransmitters can probably explain the long-recognized effects of psychological factors on the burden of cancer. We begin with an introduction on the tumor-nervous-connections and a description of the perineural invasion and neoneurogenesis, the two most important interaction patterns of cancer and nerves. Next, we discuss the most recent data that unequivocally demonstrate the necessity of the nervous system for tumor onset and growth. We introduce the molecular players of the tumor-nervous-connections by citing the role of three main families: neurotropic factors, axon guidance molecules, and neurotransmitters. Finally, we review the role the most important neurotransmitters in tumor biology and we conclude by analyzing the significance of the presented data for cancer therapy, with all the potential advantages and caveats.

Repurposing psychiatric drugs as anti-cancer agents

Cancer is a major public health problem and one of the leading contributors to the global disease burden. The high cost of development of new drugs and the increasingly severe burden of cancer globally have led to increased interest in the search and development of novel, affordable anti-neoplastic medications. Antipsychotic drugs have a long history of clinical use and tolerable safety; they have been used as good targets for drug repurposing. Being used for various psychiatric diseases for decades, antipsychotic drugs are now reported to have potent anti-cancer properties against a wide variety of malignancies in addition to their antipsychotic effects. In this review, an overview of repurposing various psychiatric drugs for cancer treatment is presented, and the putative mechanisms for the anti-neoplastic actions of these antipsychotic drugs are reviewed.

Identification of antipsychotic drug fluspirilene as a potential anti-glioma stem cell drug

Glioma stem cell (GSC)-targeted therapy is expected to be one of the most innovative approaches to treat patients with glioblastoma (GBM). A number of the drugs that restrain the signaling pathway essential for GSC maintenance have been under clinical trials. Here, we identified fluspirilene, a traditional antipsychotic drug, as a GSC-targeting agent, selected from thousands of existing drugs, and investigated its therapeutic effects against GBM with the purpose of drug repositioning. To develop novel therapeutics targeting GSCs, we initially screened drug libraries for small-molecule compounds showing a greater efficacy, compared to that of controls, in inhibiting the proliferation and survival of different GSC lines using cell proliferation assay. Drugs already reported to show therapeutic effects against GBM or those under clinical trials were excluded from subsequent screening. Finally, we found three drugs showing remarkable antiproliferative effects on GSCs at low concentrations and investigated their therapeutic effects on GSCs, glioma cell lines, and in a GBM mouse model. Of the three compounds, fluspirilene demonstrated a significant inhibitory effect on the proliferation and invasion of glioma cells as well as in the model mice treated with the drug. These effects were associated with the inactivation of the signal transducer and activator of transcription 3 (STAT3). Redeveloping of fluspirilene is a promising approach for the treatment of GBM.

Multiplexed RNAi therapy against brain tumor-initiating cells via lipopolymeric nanoparticle infusion delays glioblastoma progression

Brain tumor-initiating cells (BTICs) have been identified as key contributors to therapy resistance, recurrence, and progression of diffuse gliomas, particularly glioblastoma (GBM). BTICs are elusive therapeutic targets that reside across the blood-brain barrier, underscoring the urgent need to develop novel therapeutic strategies. Additionally, intratumoral heterogeneity and adaptations to therapeutic pressure by BTICs impede the discovery of effective anti-BTIC therapies and limit the efficacy of individual gene targeting. Recent discoveries in the genetic and epigenetic determinants of BTIC tumorigenesis offer novel opportunities for RNAi-mediated targeting of BTICs. Here we show that BTIC growth arrest in vitro and in vivo is accomplished via concurrent siRNA knockdown of four transcription factors (SOX2, OLIG2, SALL2, and POU3F2) that drive the proneural BTIC phenotype delivered by multiplexed siRNA encapsulation in the lipopolymeric nanoparticle 7C1. Importantly, we demonstrate that 7C1 nano-encapsulation of multiplexed RNAi is a viable BTIC-targeting strategy when delivered directly in vivo in an established mouse brain tumor. Therapeutic potential was most evident via a convection-enhanced delivery method, which shows significant extension of median survival in two patient-derived BTIC xenograft mouse models of GBM. Our study suggests that there is potential advantage in multiplexed targeting strategies for BTICs and establishes a flexible nonviral gene therapy platform with the capacity to channel multiplexed RNAi schemes to address the challenges posed by tumor heterogeneity.