Lithium inhibits invasion of glioma cells; possible involvement of glycogen synthase kinase-3

Unrevealing Lithium Repositioning in the Hallmarks of Cancer: Effects of Lithium Salts (LiCl and Li2CO3) in an In Vitro Cervical Cancer Model

Lithium, a natural element, has been employed as a mental stabilizer in psychiatric treatments; however, some reports indicate it has an anticancer effect, prompting the consideration of repurposing lithium for cancer treatment. The potential anticancer use of lithium may depend on its form (salt type) and the type of cancer cells targeted. Little is known about the effects of Li2CO3 or LiCl on cancer cells, so we focused on exploring their effects on proliferation, apoptosis, migration, and cell cycle as part of the hallmarks of cancer. Firstly, we established the IC50 values on HeLa, SiHa, and HaCaT cells with LiCl and Li2CO3 and determined by crystal violet that cell proliferation was time-dependent in the three cell lines (IC50 values for LiCl were 23.43 mM for SiHa, 23.14 mM for HeLa, and 15.10 mM for HaCaT cells, while the IC50 values for Li2CO3 were 20.57 mM for SiHa, 11.52 mM for HeLa, and 10.52 mM for HaCaT cells.) Our findings indicate that Li2CO3 and LiCl induce DNA fragmentation and caspase-independent apoptosis, as shown by TUNEL, Western Blot, and Annexin V/IP assay by flow cytometry. Also, cell cycle analysis showed that LiCl and Li2CO3 arrested the cervical cancer cells at the G1 phase. Moreover, lithium salts displayed an anti-migratory effect on the three cell lines observed by the wound-healing assay. All these findings imply the viable anticancer effect of lithium salts by targeting several of the hallmarks of cancer.

Sidechain structure-activity relationships of cyclobutane-based small molecule αvβ3 antagonists

The integrin family of cell surface extracellular matrix binding proteins are key to several physiological processes involved in tissue development, as well as cancer proliferation and dissemination. They are therefore attractive targets for drug discovery with cancer and non-cancer applications. We have developed a new integrin antagonist chemotype incorporating a functionalised cyclobutane ring as the central scaffold in an arginine-glycine-aspartic acid mimetic structure. Here, we report the synthesis of cyclobutanecarboxylic acids and cyclobutylamines with tetrahydronaphthyridine and aminopyridine arginine mimetic sidechains and masked carboxylic acid aspartic acid mimetic sidechains of varying length. Effective αvβ3 antagonists and new aspartic acid mimetics were identified in cell-based adhesion and invasion assays. A lead compound selected based on in vitro activity (IC50 < 1 μM), stability (t 1/2 > 80 minutes) and synthetic tractability was well-tolerated in vivo. These results show the promise of this synthetic approach for developing αvβ3 antagonists and provide a firm foundation to progress into advanced preclinical evaluation prior to progression towards the clinic. Additionally, they highlight the use of functionalised cyclobutanes as metabolically stable core structures and a straightforward and robust method for their synthesis. This important contribution to the medicinal chemists' toolbox paves the way for increased use of cyclobutanes in drug discovery.

Pharmacological Modulation of the Cytosolic Oscillator Affects Glioblastoma Cell Biology

The circadian system is a conserved time-keeping machinery that regulates a wide range of processes such as sleep/wake, feeding/fasting, and activity/rest cycles to coordinate behavior and physiology. Circadian disruption can be a contributing factor in the development of metabolic diseases, inflammatory disorders, and higher risk of cancer. Glioblastoma (GBM) is a highly aggressive grade 4 brain tumor that is resistant to conventional therapies and has a poor prognosis after diagnosis, with a median survival of only 12-15 months. GBM cells kept in culture were shown to contain a functional circadian oscillator. In seeking more efficient therapies with lower side effects, we evaluated the pharmacological modulation of the circadian clock by targeting the cytosolic kinases glycogen synthase kinase-3 (GSK-3) and casein kinase 1 ε/δ (CK1ε/δ) with specific inhibitors (CHIR99021 and PF670462, respectively), the cryptochrome protein stabilizer (KL001), or circadian disruption after Per2 knockdown expression in GBM-derived cells. CHIR99021-treated cells had a significant effect on cell viability, clock protein expression, migration, and cell cycle distribution. Moreover, cultures exhibited higher levels of reactive oxygen species and alterations in lipid droplet content after GSK-3 inhibition compared to control cells. The combined treatment of CHIR99021 with temozolomide was found to improve the effect on cell viability compared to temozolomide therapy alone. Per2 disruption affected both GBM migration and cell cycle progression. Overall, our results suggest that pharmacological modulation or molecular clock disruption severely affects GBM cell biology.

New Advances in the Pharmacology and Toxicology of Lithium: A Neurobiologically Oriented Overview

Over the last six decades, lithium has been considered the gold standard treatment for the long-term management of bipolar disorder due to its efficacy in preventing both manic and depressive episodes as well as suicidal behaviors. Nevertheless, despite numerous observed effects on various cellular pathways and biologic systems, the precise mechanism through which lithium stabilizes mood remains elusive. Furthermore, there is recent support for the therapeutic potential of lithium in other brain diseases. This review offers a comprehensive examination of contemporary understanding and predominant theories concerning the diverse mechanisms underlying lithium's effects. These findings are based on investigations utilizing cellular and animal models of neurodegenerative and psychiatric disorders. Recent studies have provided additional support for the significance of glycogen synthase kinase-3 (GSK3) inhibition as a crucial mechanism. Furthermore, research has shed more light on the interconnections between GSK3-mediated neuroprotective, antioxidant, and neuroplasticity processes. Moreover, recent advancements in animal and human models have provided valuable insights into how lithium-induced modifications at the homeostatic synaptic plasticity level may play a pivotal role in its clinical effectiveness. We focused on findings from translational studies suggesting that lithium may interface with microRNA expression. Finally, we are exploring the repurposing potential of lithium beyond bipolar disorder. These recent findings on the therapeutic mechanisms of lithium have provided important clues toward developing predictive models of response to lithium treatment and identifying new biologic targets. SIGNIFICANCE STATEMENT: Lithium is the drug of choice for the treatment of bipolar disorder, but its mechanism of action in stabilizing mood remains elusive. This review presents the latest evidence on lithium's various mechanisms of action. Recent evidence has strengthened glycogen synthase kinase-3 (GSK3) inhibition, changes at the level of homeostatic synaptic plasticity, and regulation of microRNA expression as key mechanisms, providing an intriguing perspective that may help bridge the mechanistic gap between molecular functions and its clinical efficacy as a mood stabilizer.

Wnt Signaling in Brain Tumors: A Challenging Therapeutic Target

The involvement of Wnt signaling in normal tissue homeostasis and disease has been widely demonstrated over the last 20 years. In particular, dysregulation of Wnt pathway components has been suggested as a relevant hallmark of several neoplastic malignancies, playing a role in cancer onset, progression, and response to treatments. In this review, we summarize the current knowledge on the instructions provided by Wnt signaling during organogenesis and, particularly, brain development. Moreover, we recapitulate the most relevant mechanisms through which aberrant Wnt pathway activation may impact on brain tumorigenesis and brain tumor aggressiveness, with a particular focus on the mutual interdependency existing between Wnt signaling components and the brain tumor microenvironment. Finally, the latest anti-cancer therapeutic approaches employing the specific targeting of Wnt signaling are extensively reviewed and discussed. In conclusion, here we provide evidence that Wnt signaling, due to its pleiotropic involvement in several brain tumor features, may represent a relevant target in this context, although additional efforts will be needed to: (i) demonstrate the real clinical impact of Wnt inhibition in these tumors; (ii) overcome some still unsolved concerns about the potential systemic effects of such approaches; (iii) achieve efficient brain penetration.

Lithium: A Promising Anticancer Agent

Lithium is a therapeutic cation used to treat bipolar disorders but also has some important features as an anti-cancer agent. In this review, we provide a general overview of lithium, from its transport into cells, to its innovative administration forms, and based on genomic, transcriptomic, and proteomic data. Lithium formulations such as lithium acetoacetate (LiAcAc), lithium chloride (LiCl), lithium citrate (Li3C6H5O7), and lithium carbonate (Li2CO3) induce apoptosis, autophagy, and inhibition of tumor growth and also participate in the regulation of tumor proliferation, tumor invasion, and metastasis and cell cycle arrest. Moreover, lithium is synergistic with standard cancer therapies, enhancing their anti-tumor effects. In addition, lithium has a neuroprotective role in cancer patients, by improving their quality of life. Interestingly, nano-sized lithium enhances its anti-tumor activities and protects vital organs from the damage caused by lipid peroxidation during tumor development. However, these potential therapeutic activities of lithium depend on various factors, such as the nature and aggressiveness of the tumor, the type of lithium salt, and its form of administration and dosage. Since lithium has been used to treat bipolar disorder, the current study provides an overview of its role in medicine and how this has changed. This review also highlights the importance of this repurposed drug, which appears to have therapeutic cancer potential, and underlines its molecular mechanisms.

Lithium in Cancer Therapy: Friend or Foe?

Lithium, a trace element important for fetal health and development, is considered a metal drug with a well-established clinical regime, economical production process, and a mature storage system. Several studies have shown that lithium affects tumor development by regulating inositol monophosphate (IMPase) and glycogen synthase kinase-3 (GSK-3). Lithium can also promote proliferation and programmed cell death (PCD) in tumor cells through a number of new targets, such as the nuclear receptor NR4A1 and Hedgehog-Gli. Lithium may increase cancer treatment efficacy while reducing side effects, suggesting that it can be used as an adjunctive therapy. In this review, we summarize the effects of lithium on tumor progression and discuss the underlying mechanisms. Additionally, we discuss lithium's limitations in antitumor clinical applications, including its narrow therapeutic window and potential pro-cancer effects on the tumor immune system.

Tau Protein as Therapeutic Target for Cancer? Focus on Glioblastoma

Despite being extensively studied for several decades, the microtubule-associated protein Tau has not finished revealing its secrets. For long, Tau has been known for its ability to promote microtubule assembly. A less known feature of Tau is its capability to bind to cancer-related protein kinases, suggesting a possible role of Tau in modulating microtubule-independent cellular pathways that are associated with oncogenesis. With the intention of finding new therapeutic targets for cancer, it appears essential to examine the interaction of Tau with these kinases and their consequences. This review aims at collecting the literature data supporting the relationship between Tau and cancer with a particular focus on glioblastoma tumors in which the pathological significance of Tau remains largely unexplored. We will first treat this subject from a mechanistic point of view showing the pivotal role of Tau in oncogenic processes. Then, we will discuss the involvement of Tau in dysregulating critical pathways in glioblastoma. Finally, we will outline promising strategies to target Tau protein for the therapy of glioblastoma.

Phosphorylation of PI3K/Akt at Thr308, but not MAPK kinase, mediates lithium-induced neuroprotection against cerebral ischemia in mice

Lithium, in addition to its effect on acute and long-term bipolar disorder, is involved in neuroprotection after ischemic stroke. Yet, its mechanism of action is still poorly understood, which was only limited to its modulatory effect on GSK pathway. Therefore, we initially analyzed the dose-dependent effects of lithium on neurological deficits, infarct volume, brain edema and blood-brain barrier integrity, along with neuronal injury and survival in mice subjected to focal cerebral ischemia. Thereafter, we investigated the involvement of the PI3K/Akt and MEK signal transduction pathways and their components. Our observations revealed that 2 mmol/kg lithium significantly improved post-ischemic brain tissue survival. Although, 2 mmol/kg lithium had no negative effect on brain microcirculation, 5 and 20 mmol/kg lithium reduced brain perfusion. Furthermore, supratherapeutic dose of lithium in 20 mmol/kg lead to animal death. In addition, improvement of brain perfusion with L-arginine, did not change the effect of 5 mmol/kg lithium on brain injury. Additionally, post-stroke blood-brain barrier leakage, hemodynamic impairment and apoptosis have been reversed by lithium treatment. Interestingly, lithium-induced neuroprotection was associated with increased phosphorylation of Akt at Thr308 and suppressed GSK-3β phosphorylation at Ser9 residue. Lithium upregulated Erk-2 and downregulated JNK-2 phosphorylation. To distinguish whether neuroprotective effects of lithium are modulated by PI3K/Akt or MEK, we sequentially blocked these pathways and demonstrated that the neuroprotective activity of lithium persisted during MEK/ERK inhibition, whereas PI3K/Akt inhibition abolished neuroprotection. Collectively, we demonstrated lithium exerts its post-stroke neuroprotective activity via the PI3K/Akt pathway, specifically via Akt phosphorylation at Thr308, but not via MEK/ERK.

Wnt and PI3K/Akt/mTOR Survival Pathways as Therapeutic Targets in Glioblastoma

Glioblastoma (GBM) is a devastating type of brain tumor, and current therapeutic treatments, including surgery, chemotherapy, and radiation, are palliative at best. The design of effective and targeted chemotherapeutic strategies for the treatment of GBM require a thorough analysis of specific signaling pathways to identify those serving as drivers of GBM progression and invasion. The Wnt/β-catenin and PI3K/Akt/mTOR (PAM) signaling pathways are key regulators of important biological functions that include cell proliferation, epithelial–mesenchymal transition (EMT), metabolism, and angiogenesis. Targeting specific regulatory components of the Wnt/β-catenin and PAM pathways has the potential to disrupt critical brain tumor cell functions to achieve critical advancements in alternative GBM treatment strategies to enhance the survival rate of GBM patients. In this review, we emphasize the importance of the Wnt/β-catenin and PAM pathways for GBM invasion into brain tissue and explore their potential as therapeutic targets.

Drug Resistance in Glioma Cells Induced by a Mesenchymal-Amoeboid Migratory Switch

Cancer cell invasion is a precondition for tumour metastasis and represents one of the most devastating characteristics of cancer. The development of drugs targeting cell migration, known as migrastatics, may improve the treatment of highly invasive tumours such as glioblastoma (GBM). In this study, investigations into the role of the cell adhesion protein Cellular communication network factor 1 (CCN1, also known as CYR61) in GBM cell migration uncovered a drug resistance mechanism adopted by cells when treated with the small molecule inhibitor CCG-1423. This inhibitor binds to importin α/β inhibiting the nuclear translocation of the transcriptional co-activator MKL1, thus preventing downstream effects including migration. Despite this reported role as an inhibitor of cell migration, we found that CCG-1423 treatment did not inhibit GBM cell migration. However, we could observe cells now migrating by mesenchymal-amoeboid transition (MAT). Furthermore, we present evidence that CCN1 plays a critical role in the progression of GBM with increased expression in higher-grade tumours and matched blood samples. These findings support a potential role for CCN1 as a biomarker for the monitoring and potentially early prediction of GBM recurrence, therefore as such could help to improve treatment of and increase survival rates of this devastating disease.

Drug repositioning: Using psychotropic drugs for the treatment of glioma

Psychotropic drugs can penetrate the blood-brain barrier and regulate the levels of neurotransmitters and neuromodulators such as γ-aminobutyric acid, glutamate, serotonin, dopamine, and norepinephrine in the brain, and thus influence neuronal activity. Neuronal activity in the tumor microenvironment can promote the growth and expansion of glioma. There is increasing evidence that in addition to their use in the treatment of mental disorders, antipsychotic, antidepressant, and mood-stabilizing drugs have clinical potential for cancer therapy. These drugs have been shown to inhibit the malignant progression of glioma by targeting signaling pathways related to cell proliferation, apoptosis, or invasion/migration or by increasing the sensitivity of glioma cells to conventional chemotherapy or radiotherapy. In this review, we summarize findings from preclinical and clinical studies investigating the use of antipsychotics, antidepressants, and mood stabilizers in the treatment of various types of cancer, with a focus on glioma; and discuss their presumed antitumor mechanisms. The existing evidence indicates that psychotropic drugs with established pharmacologic and safety profiles can be repurposed as anticancer agents, thus providing new options for the treatment of glioma.

Crosstalk of the Wnt/β-Catenin Signaling Pathway in the Induction of Apoptosis on Cancer Cells

The Wnt/β-catenin signaling pathway plays a major role in cell survival and proliferation, as well as in angiogenesis, migration, invasion, metastasis, and stem cell renewal in various cancer types. However, the modulation (either up- or downregulation) of this pathway can inhibit cell proliferation and apoptosis both through β-catenin-dependent and independent mechanisms, and by crosstalk with other signaling pathways in a wide range of malignant tumors. Existing studies have reported conflicting results, indicating that the Wnt signaling can have both oncogenic and tumor-suppressing roles, depending on the cellular context. This review summarizes the available information on the role of the Wnt/β-catenin pathway and its crosstalk with other signaling pathways in apoptosis induction in cancer cells and presents a modified dual-signal model for the function of β-catenin. Understanding the proapoptotic mechanisms induced by the Wnt/β-catenin pathway could open new therapeutic opportunities.

Lithium and Therapeutic Targeting of GSK-3

Lithium salts have been in the therapeutic toolbox for better or worse since the 19th century, with purported benefit in gout, hangover, insomnia, and early suggestions that lithium improved psychiatric disorders. However, the remarkable effects of lithium reported by John Cade and subsequently by Mogens Schou revolutionized the treatment of bipolar disorder. The known molecular targets of lithium are surprisingly few and include the signaling kinase glycogen synthase kinase-3 (GSK-3), a group of structurally related phosphomonoesterases that includes inositol monophosphatases, and phosphoglucomutase. Here we present a brief history of the therapeutic uses of lithium and then focus on GSK-3 as a therapeutic target in diverse diseases, including bipolar disorder, cancer, and coronavirus infections.

Drug repurposing towards targeting cancer stem cells in pediatric brain tumors

In the pediatric population, brain tumors represent the most commonly diagnosed solid neoplasms and the leading cause of cancer-related deaths globally. They include low-grade gliomas (LGGs), medulloblastomas (MBs), and other embryonal, ependymal, and neuroectodermal tumors. The mainstay of treatment for most brain tumors includes surgical intervention, radiation therapy, and chemotherapy. However, resistance to conventional therapy is widespread, which contributes to the high mortality rates reported and lack of improvement in patient survival despite advancement in therapeutic research. This has been attributed to the presence of a subpopulation of cells, known as cancer stem cells (CSCs), which reside within the tumor bulk and maintain self-renewal and recurrence potential of the tumor. An emerging promising approach that enables identifying novel therapeutic strategies to target CSCs and overcome therapy resistance is drug repurposing or repositioning. This is based on using previously approved drugs with known pharmacokinetic and pharmacodynamic characteristics for indications other than their traditional ones, like cancer. In this review, we provide a synopsis of the drug repurposing methodologies that have been used in pediatric brain tumors, and we argue how this selective compilation of approaches, with a focus on CSC targeting, could elevate drug repurposing to the next level.

The Effect of Lithium on Inflammation-Associated Genes in Lipopolysaccharide-Activated Raw 264.7 Macrophages

Lithium remains the preferred Food and Drug Administration- (FDA-) approved psychiatric drug for treatment of bipolar disorders since its medical establishment more than half a century ago. Recent studies revealed a promising role for lithium in the regulation of inflammation, oxidative stress, and neurodegeneration albeit unclear about its exact mode of action. Thus, the intention of this study is to delineate the regulatory mechanisms of lithium on oxidative stress in lipopolysaccharide- (LPS-) activated macrophages by evaluating its effects on nuclear factor-κB (NF-κB) activity and mRNA expression of multiple oxidative stress-related NF-κB genes. Raw 264.7 macrophages were treated with up to 10 mM lithium, and no change in cell proliferation, viability, growth, and cell adhesion was observed in real time. Pretreatment with low doses of lithium was shown to reduce nitric oxide (NO) production in LPS-activated macrophages. A reduced internal H₂DCFDA fluorescence intensity, indicative of reduced reactive oxygen species (ROS) production, was observed in LPS-activated Raw 264.7 macrophages treated with lithium. Lithium has been shown to lower the production of the chemokine RANTES; furthermore, this inhibitory action of lithium has been suggested to be independent of glycogen synthase kinase-3 β (GSK3β) activity. It is shown here that lithium modulates the expression of several inflammatory genes including IκB-α, TRAF3, Tollip, and NF-κB1/p50 which are regulators of the NF-κB pathway. Moreover, lithium inhibits NF-κB activity by lowering nuclear translocation of NF-κB in LPS-activated macrophages. This is the first study to associate Tollip, Traf-3, and IκB-α mRNA expression with lithium effect on NF-κB activity in LPS-activated Raw 264.7 macrophages. Although these effects were obtained using extratherapeutic concentrations of lithium, results of this study provide useful information towards understanding the mode of action of lithium. This study associates lithium with reduced oxidative stress in LPS-activated Raw 264.7 macrophages and further suggests candidate molecular targets for the regulation of oxidative stress-related diseases using lithium beyond bipolar disorders.

Glycogen Synthase Kinase 3β in Cancer Biology and Treatment

Glycogen synthase kinase (GSK)3β is a multifunctional serine/threonine protein kinase with more than 100 substrates and interacting molecules. GSK3β is normally active in cells and negative regulation of GSK3β activity via phosphorylation of its serine 9 residue is required for most normal cells to maintain homeostasis. Aberrant expression and activity of GSK3β contributes to the pathogenesis and progression of common recalcitrant diseases such as glucose intolerance, neurodegenerative disorders and cancer. Despite recognized roles against several proto-oncoproteins and mediators of the epithelial–mesenchymal transition, deregulated GSK3β also participates in tumor cell survival, evasion of apoptosis, proliferation and invasion, as well as sustaining cancer stemness and inducing therapy resistance. A therapeutic effect from GSK3β inhibition has been demonstrated in 25 different cancer types. Moreover, there is increasing evidence that GSK3β inhibition protects normal cells and tissues from the harmful effects associated with conventional cancer therapies. Here, we review the evidence supporting aberrant GSK3β as a hallmark property of cancer and highlight the beneficial effects of GSK3β inhibition on normal cells and tissues during cancer therapy. The biological rationale for targeting GSK3β in the treatment of cancer is also discussed at length.

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.

The contribution of ketone bodies to glycolytic inhibition for the treatment of adult and pediatric glioblastoma

PURPOSE

Glioblastoma (GBM) remains one of the most lethal primary brain tumors in children and adults. Targeting tumor metabolism has emerged as a promising-targeted therapeutic strategy for GBM and characteristically resistant GBM stem-like cells (GSCs).

METHODS

Gene expression data was obtained from the online patient-histology database, GlioVis. GSC mitochondria morphology was examined by TEM. Cell viability and effect on GSC self-renewal was determined via MTS assay and neurosphere assay, respectively. Proteins were evaluated by Western Blot.

RESULTS

Enzymes necessary for ketone catabolism (BDH1, OXCT1 and ACAT1) are significantly downregulated in adult and pediatric GBM. GSC mitochondrial ultrastructure suggested defects in oxidative phosphorylation. Treatment of both GBM and GSC cell lines resulted in dose-dependent decreases in viability in response to glycolytic inhibitor 2-deoxy-D-glucose (2-DG), and ketone body Acetoacetate (AA), but not β-hydroxybutyrate (βHB). AA induced apoptosis was confirmed by western blot analysis, indicating robust caspase activation and PARP cleavage. AA reduced neurosphere formation at concentrations as low as 1 mM. Combined treatment of low dose 2-DG (50 μM) with AA resulted in more cell death than either treatment alone. The effect was greater than additive at low concentrations of AA, reducing viability approximately 50% at 1 mM AA. AA was found to directly upregulate mitochondrial uncoupling protein 2 (UCP2), which may explain this potential drug synergism via multi-faceted inhibition of the glycolytic pathway.

CONCLUSION

Targeting the metabolic pathway of GBM via glycolytic inhibition in conjunction with ketogenic diet or exogenous ketone body supplementation warrants further investigation as a promising adjunctive treatment to conventional therapy.

High Dosage Lithium Treatment Induces DNA Damage and p57Kip2 Decrease

Lithium salt is the first-line therapeutic option for bipolar disorder and has been proposed as a potential antitumoral drug. The effects of LiCl treatment were investigated in SH-SY5Y, a human neuroblastoma cell line and an in vitro model of dopaminergic neuronal differentiation. LiCl, at the dosage used in psychiatric treatment, does not affect cell proliferation, while at higher doses it delays the SH-SY5Y cell division cycle and for prolonged usage reduces cell viability. Moreover, the ion treatment affects DNA integrity as demonstrated by accumulation of p53 and γH2AX (the phosphorylated form of H2AX histone), two important markers of genome damage. p57^Kip2, a CIP/Kip protein, is required for proper neuronal maturation and represents a main factor of response to stress including genotoxicity. We evaluated the effect of lithium on p57^Kip2 levels. Unexpectedly, we found that lithium downregulates the level of p57^Kip2 in a dose-dependent manner, mainly acting at the transcriptional level. A number of different approaches, mostly based on p57^Kip2 content handling, confirmed that the CKI/Kip reduction plays a key role in the DNA damage activated by lithium and suggests the unanticipated view that p57^Kip2 might be involved in DNA double-strand break responses. In conclusion, our study identified novel roles for p57^Kip2 in the molecular mechanism of lithium at high concentration and, more in general, in the process of DNA repair.

Repression of PCGF1 Decreases the Proliferation of Glioblastoma Cells in Association with Inactivation of c-Myc Signaling Pathway

Purpose

Glioblastoma (GBM) is the most common primary brain tumor with a poor therapeutic outcome. Polycomb group factor 1 (PCGF1), a member of the PcG (Polycomb group) family, is highly expressed in the developing nervous system of mice. However, the function and the mechanism of PCGF1 in GBM proliferation still remain unclear.

Methods

Knockdown of PCGF1 was performed in U87 GBM cell by shRNA strategy via lentivirus vector. MTT assay, colony formation assays, and flow cytometry were used to measure the properties of cell proliferation and cell cycle distribution, respectively. GeneChip analysis was performed to identify the downstream effector molecules. Rescue assay was constructed to verify the screening results.

Results

We first found that knockdown of PCGF1 led to the inhibition of U87 cells proliferation and decreased colony formation ability. The data from GeneChip expression profiling and Ingenuity Pathway Analysis (IPA) indicated that many of the altered gene cells are associated with the cell proliferation control pathways. We have further confirmed the suppression of AKT/GSK3β/c-Myc/cyclinD1 expressions by Western blotting analysis. The over-expression of c-Myc could partly restore the attenuated proliferation ability caused by knockdown of PCGF1.

Conclusion

All the above evidences suggested that PCGF1 might be closely associated with tumorigenesis and progression of glioblastoma (GBM), in which process the oncoprotein c-Myc may participate. PCGF1 could thus be a potential therapeutic target for the treatment of glioblastoma (GBM).

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.

The Psychiatric Drug Lithium Increases DNA Damage and Decreases Cell Survival in MCF-7 and MDA-MB-231 Breast Cancer Cell Lines Expos ed to Ionizing Radiation

Background:

Breast cancer is the most common cancer among women. Radiation therapy is used for treating almost every stage of breast cancer. A strategy to reduce irradiation side effects and to decrease the recurrence of cancer is concurrent use of radiation and radiosensitizers. We studied the effect of the antimanic drug lithium on radiosensitivity of estrogen-receptor (ER)-positive MCF-7 and ER-negative, invasive, and radioresistant MDA-MB-231 breast cancer cell lines.

Methods:

MCF-7 and MDA-MB-231 breast cancer cell lines were treated with 30 mM and 20 mM concentrations of lithium chloride (LiCl), respectively. These concentrations were determined by MTT viability assay. Growth curves were depicted and comet assay was performed for control and LiCl-treated cells after exposure to X-ray. Total and phosphorylated inactive levels of glycogen synthase kinase-3beta (GSK-3β) protein were determined by ELISA assay for control and treated cells.

Results:

Treatment with LiCl decreased cell proliferation after exposure to X-ray as indicated by growth curves of MCF-7 and MDA-MB-231 cell lines within six days following radiation. Such treatment increased the amount of DNA damages represented by percent DNA in Tails of comets at 0, 1, 4, and even 24 hours after radiation in both studied cell lines. The amount of active GSK-3β was increased in LiCl-treated cells in ER-positive and ER-negative breast cancer cell lines.

Conclusion:

Treatment with LiCl that increased the active GSK-3β protein, increased DNA damages and decreased survival independent of estrogen receptor status in breast cancer cells exposed to ionizing radiation.

HIF-1α/Wnt signaling-dependent control of gene transcription regulates neuronal differentiation of glioblastoma stem cells

HIF-1α has been suggested to interplay with Wnt signaling components in order to activate a neuronal differentiation process in both normal brain and glioblastoma (GBM). Based on these data, we explored the molecular mechanisms underlying the observed capability of GBM cells to acquire a neuronal phenotype upon Wnt signaling stimulation and how the microenvironment, particularly hypoxia, modulates this process.

Methods: here, the employment of ChIP-seq techniques together with co-immunoprecipitation approaches allowed to reconstruct the molecular interactions responsible for activating specific pro-differentiating transcriptional programs in GBM cells. Moreover, gene silencing/over-expression approaches coupled with the functional analysis of cell phenotype were applied to confirm ChIP-driven hypotheses. Finally, we combined the use of publicly available gene expression datasets with protein expression data by immunohistochemistry to test the clinical relevance of obtained results.

Results: our data clearly suggest that HIF-1α is recruited by the β-catenin/TCF1 complex to foster neuronal differentiation gene transcription in hypoxic GBM cells. Conversely, at higher oxygen levels, the increased expression of TCF4 exerts a transcriptional inhibitory function on the same genomic regions, thus counteracting differentiation. Moreover, we demonstrate the existence of a positive correlation between the expression levels of HIF-1α, TCF1 and neuronal phenotype in GBM tumors, accompanied by the over-expression of several Wnt signaling components, finally affecting patient prognosis.

Conclusion: we unveiled a peculiar mechanism by which TCF1 and HIF-1α can induce a reminiscent neuronal differentiation of hypoxic GBM cells, which is hampered, in normoxia, by high levels of TCF4, thus not only de facto controlling the balance between differentiation and stemness, but also impacting on intra-tumoral heterogeneity and eventually patient outcome.

Lithium and Not Acetoacetate Influences the Growth of Cells Treated with Lithium Acetoacetate

The ketogenic diet (KD), a high-fat/low-carbohydrate/adequate-protein diet, has been proposed as a treatment for a variety of diseases, including cancer. KD leads to generation of ketone bodies (KBs), predominantly acetoacetate (AcAc) and 3-hydroxy-butyrate, as a result of fatty acid oxidation. Several studies investigated the antiproliferative effects of lithium acetoacetate (LiAcAc) and sodium 3-hydroxybutyrate on cancer cells in vitro. However, a critical point missed in some studies using LiAcAc is that Li ions have pleiotropic effects on cell growth and cell signaling. Thus, we tested whether Li ions per se contribute to the antiproliferative effects of LiAcAc in vitro. Cell proliferation was analyzed on neuroblastoma, renal cell carcinoma, and human embryonic kidney cell lines. Cells were treated for 5 days with 2.5, 5, and 10 mM LiAcAc and with equimolar concentrations of lithium chloride (LiCl) or sodium chloride (NaCl). LiAcAc affected the growth of all cell lines, either negatively or positively. However, the effects of LiAcAc were always similar to those of LiCl. In contrast, NaCl showed no effects, indicating that the Li ion impacts cell proliferation. As Li ions have significant effects on cell growth, it is important for future studies to include sources of Li ions as a control.

Emerging therapeutic potential of anti-psychotic drugs in the management of human glioma: A comprehensive review

Despite numerous advancements in the last decade, human gliomas such as astrocytoma and glioblastoma multiforme have the worst prognoses among all cancers. Anti-psychotic drugs are commonly prescribed to treat mental disorders among cancer patients, and growing empirical evidence has revealed their antitumor, anti-metastatic, anti-angiogenic, anti-proliferative, chemo-preventive, and neo-adjuvant efficacies in various in vitro, in vivo, and clinical glioma models. Anti-psychotic drugs have drawn the attention of physicians and researchers owing to their beneficial effects in the prevention and treatment of gliomas. This review highlights data on the therapeutic potential of various anti-psychotic drugs as anti-proliferative, chemopreventive, and anti-angiogenic agents in various glioma models via the modulation of upstream and downstream molecular targets involved in apoptosis, autophagy, oxidative stress, inflammation, and the cell cycle in in vitro and in vivo preclinical and clinical stages among glioma patients. The ability of anti-psychotic drugs to modulate various signaling pathways and multidrug resistance-conferring proteins that enhance the efficacy of chemotherapeutic drugs with low side-effects exemplifies their great potential as neo-adjuvants and potential chemotherapeutics in single or multimodal treatment approach. Moreover, anti-psychotic drugs confer the ability to induce glioma into oligodendrocyte-like cells and neuronal-like phenotype cells with reversal of epigenetic alterations through inhibition of histone deacetylase further rationalize their use in glioma treatment. The improved understanding of anti-psychotic drugs as potential chemotherapeutic drugs or as neo-adjuvants will provide better information for their use globally as affordable, well-tolerated, and effective anticancer agents for human glioma.

Proteomic Analysis Implicates Vimentin in Glioblastoma Cell Migration

We previously showed lithium chloride (LiCl) and other inhibitors of glycogen synthase kinase-3 (GSK-3) including 6-bromo-indirubin-3-oxime (BIO), can block glioblastoma (GBM) cell migration. To investigate the mechanisms involved we used two-dimensional difference in-gel electrophoresis (2D-DIGE) and mass spectrometry to identify proteins altered after treatment of U251 GBM cells with 20 mM LiCl. Downregulation of the intermediate filament protein vimentin was the most significant change identified. Analysis of patient tumor samples revealed that vimentin is expressed abundantly in GBM, and is prognostic especially in lower grade tumors. Additionally, siRNA-mediated vimentin knockdown impaired GBM migration. Western blotting showed that treatment with LiCl or small molecule GSK-3 inhibitors led to the rapid downregulation of detergent soluble vimentin levels across a panel of GBM-derived cells. Fluorescence reactivation after photobleaching (FRAP) microscopy studies showed a significant reduction in the ability of the vimentin cytoskeleton to recover from photo-bleaching in the presence of LiCl or BIO. Biochemical studies revealed that GSK-3 and vimentin directly interact, and analysis of vimentin revealed a GSK-3 consensus phosphorylation site. We conclude that anti-migratory compounds with the ability to inhibit GSK-3 have effects on vimentin cytoskeletal dynamics, which may play a role in their anti-invasive activity.

Effects of GADL1 overexpression on cell migration and the associated morphological changes

Lithium has been used for maintenance treatment of bipolar disorder, but drug response varies among patients. Single-nucleotide polymorphisms in glutamate decarboxylase–like protein 1 (GADL1) are found to be associated with lithium response in Han Chinese bipolar patients. In this study, we assessed GADL1 function using a neuroblastoma cell line that stably overexpressed GADL1. Genes encoding factors involved in cell migration, such as FN1, ITGA2, ITGAV and CCL2, were downregulated in GADL1-overexpressing cells. GADL1 overexpression indeed suppressed cell migration. Cell migration speed and perimeter length exhibited similar trends, both of which were decreased under GADL1 overexpression or lithium treatment but increased upon stimulation with CCL2. Secreted GADL1 or its enzyme product, taurine, in the conditioned medium might exert only mild effects on the observed changes. Compared with SH-SY5Y cells, GADL1-overexpressing cells were much more sensitive to CCL2 treatment but less sensitive to lithium, indicating that the level of GADL1 expression can affect cell sensitivity to lithium or  CCL2 treatment. Together, these results suggest that cell migration and related morphological changes might provide good indicators of the sensitivity toward lithium treatment, and the GADL1 stable overexpression cell line might serve as a useful platform to screen novel therapeutics for bipolar disorder.

MicroRNA-451 Inhibits Migration of Glioblastoma while Making It More Susceptible to Conventional Therapy

Malignant glioblastoma (GBM, glioma) is the most common and aggressive primary adult brain tumor. The prognosis of GBM patients remains poor, despite surgery, radiation and chemotherapy. The major obstacles for successful remedy are invasiveness and therapy resistance of GBM cells. Invasive glioma cells leave primary tumor core and infiltrate surrounding normal brain leading to inevitable recurrence, even after surgical resection, radiation and chemotherapy. Therapy resistance allowing for selection of more aggressive and resistant sub-populations including GBM stem-like cells (GSCs) upon treatment is another serious impediment to successful treatment. Through their regulation of multiple genes, microRNAs can orchestrate complex programs of gene expression and act as master regulators of cellular processes. MicroRNA-based therapeutics could thus impact broad cellular programs, leading to inhibition of invasion and sensitization to radio/chemotherapy. Our data show that miR-451 attenuates glioma cell migration in vitro and invasion in vivo. In addition, we have found that miR-451 sensitizes glioma cells to conventional chemo- and radio-therapy. Our data also show that miR-451 is regulated in vivo by AMPK pathway and that AMPK/miR-451 loop has the ability to switch between proliferative and migratory pattern of glioma cells behavior. We therefore postulate that AMPK/miR-451 negative reciprocal feedback loop allows GBM cells/GSCs to adapt to tumor “ecosystem” by metabolic and behavioral flexibility, and that disruption of such a loop reduces invasiveness and diminishes therapy resistance.

Glycogen synthase kinase-3 inhibition in glioblastoma multiforme cells induces apoptosis, cell cycle arrest and changing biomolecular structure

Glioblastoma multiforme (GBM) is the most malignant and aggressive primary human brain tumors. The regulatory pathways of apoptosis are altered in GBMs, leading to a survival advantage of the tumor cells. Thus, identification of target molecules, which are effective in triggering of the cell death mechanisms in GBM, is an essential strategy for therapeutic purposes. Glycogen synthase kinase-3 (GSK-3) plays an important role in apoptosis, proliferation and cell cycle. This study focused on the effect of GSK-3 inhibitor IX in the GBM cells. Apoptosis induction was determined by Annexin-V assay, multicaspase activity and immunofluorescence analyses. Concentration-dependent effects of GSK-3 inhibitor IX on the cell cycle were also evaluated. Moreover, the effect of GSK inhibitor on the cellular biomolecules was assessed by using ATR-FTIR spectroscopy. Our assay results indicated that GSK-3 inhibitor IX induces apoptosis, resulting in a significant increase in the expression of caspase-3 and caspase-8 proteins. Cell cycle analyses revealed that GSK-3 inhibitor IX leads to dose-dependent G2/M-phase cell cycle arrest. Based on the FTIR data, treatment of GBM cells causes dysregulation in the carbohydrate metabolism and induces apoptotic cell death which was characterized by the spectral alterations in nucleic acids, an increment in the lipid amount with disordering state and compositional changes in the cellular proteins. These findings suggest that GSK-3 inhibitor IX exhibits anti-cancer effects by inducing apoptosis and changing biomolecular structure of membrane lipids, carbohydrates, nucleic acids and proteins, and thus, may be further evaluated as a potential effective candidate agent for the GBM combination therapies.

Solid stress in brain tumours causes neuronal loss and neurological dysfunction and can be reversed by lithium

The compression of brain tissue by a tumour mass is believed to be a major cause of the clinical symptoms seen in patients with brain cancer. However, the biological consequences of these physical stresses on brain tissue are unknown. Here, via imaging studies in patients and by using mouse models of human brain tumours, we show that a subgroup of primary and metastatic brain tumours, classified as nodular on the basis of their growth pattern, exert solid stress on the surrounding brain tissue, causing a decrease in local vascular perfusion as well as neuronal death and impaired function. We demonstrate a causal link between solid stress and neurological dysfunction by applying and removing cerebral compression, which respectively mimic the mechanics of tumour growth and of surgical resection. We also show that, in mice, treatment with lithium reduces solid-stress-induced neuronal death and improves motor coordination. Our findings indicate that brain-tumour-generated solid stress impairs neurological function in patients, and that lithium as a therapeutic intervention could counter these effects.

Valproic Acid Inhibits Proliferation and Reduces Invasiveness in Glioma Stem Cells Through Wnt/β Catenin Signalling Activation

Glioblastoma is the most common malignant brain tumour in adults. The failure of current therapies can be ascribed to glioma stem cells (GSCs), which can rapidly repopulate the tumour following the initial treatment. The study of histone deacetylase inhibitors, such as valproic acid (VPA), is becoming an attractive field in cancer research. However, the exact mechanisms underlying its anti-cancer effect remain to be elucidated due to its pleiotropic effects on several cell-signalling pathways. Ingenuity Pathway Analysis (IPA) bioinformatics analysis was performed on genome-wide data regarding GSCs methylome to identify the signalling pathways mainly affected by methylation changes induced by VPA. Real time PCR and luciferase reporter assay were used to better investigate VPA effects on Wnt/β-catenin signalling pathway. VPA effect on GSC proliferation was evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) and Trypan blue assays. Finally, VPA impact on GSC motility was demonstrated by Boyden chamber assay and further confirmed evaluating the expression levels or localisation, through western blot or immunofluorescence, of Twist1, Snail1, E-Cadherin and N-Cadherin. The bioinformatics analyses performed on GSCs methylome highlighted that Wnt/β-catenin signalling was affected by the methylation changes induced by VPA, which could influence its activation status. In particular, we pointed out a general activation of this pathway after VPA exposure, which was accompanied by an inhibitory potential on GSCs proliferation. Finally, we also proved VPA's ability to inhibit GSCs invasion through Snail1 and Twist1 downregulation and E-Cadherin relocalisation. VPA treatment may represent a new, interesting therapeutic approach to affect GSC proliferation and motility, but further investigations are certainly needed.

Lithium chloride attenuates mitomycin C induced necrotic cell death in MDA-MB-231 breast cancer cells via HMGB1 and Bax signaling

The clinical use of potent anticancer drug mitomycin C (MMC) has limited due to side effects and resistance of cancer cells. The aim of this study was to investigate whether lithium chloride (LiCl), as a mood stabilizer, can affect the sensitivity of MDA-MB-231 breast cancer cells to mitomycin C. The cells were exposed to various concentrations of mitomycin C alone and combined with LiCl and the viability determined by trypan blue and MTT assays. Proteins were analyzed by western blot and mRNA expression of HMGB1 MMP9 and Bcl-2 were analyzed by RT-PCR. Flow cytometry was used to determine the cell cycle arrest and percent of apoptotic and necrotic cells. Concentration of Bax assessed by ELISA. Exposure of the cells to mitomycin C revealed IC₅₀ value of 20 μM, whereas pretreatment of the cells with LiCl induced synergistic cytotoxicity and IC₅₀ value declined to 5 μM. LiCl combined with mitomycin C significantly down-regulated HMGB1, MMP9 and Bcl-2 gene expression but significantly increased the level of Bax protein. In addition, the content of HMGB1 in the nuclei decreased and pretreatment with LiCl reduced the content of HMGB1 release induced by MMC. LiCl increased mitomycin C-induced cell shrinkage and PARP fragmentation suggesting induction of apoptosis in these cells. LiCl prevented mitomycin C-induced necrosis and changed the cell death arrest at G2/M-phase. Taking all together, it is suggested that LiCl efficiently enhances mitomycin C-induced apoptosis and HMGB1, Bax and Bcl-2 expression may play a major role in this process, the findings that provide a new therapeutic strategy for LiCl in combination with mitomycin C.

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.

The Central Role of Wnt Signaling and Organoid Technology in Personalizing Anticancer Therapy

The Wnt pathway is at the heart of organoid technology, which is set to revolutionize the cancer field. We can now predetermine a patient's response to any given anticancer therapy by exposing tumor organoids established from the patient's own tumor. This cutting-edge biomedical platform translates to patients being treated with the correct drug at the correct dose from the outset, a truly personalized and precise medical approach. A high throughput drug screen on organoids also allows drugs to be tested in limitless combinations. More recently, the tumor cells that are resistant to the therapy given to a patient were selected in culture using the patient's organoids. The resistant tumor organoids were then screened empirically to identify drugs that will kill the resistant cells. This information allows diagnosis in real-time to either prevent tumor recurrence or effectively treat the recurring tumor. Furthermore, the ability to culture stem cell-derived epithelium as organoids has enabled us to begin to understand how a stem cell becomes a cancer cell or to pin-point the genetic alteration that underlies a given genetic syndrome. Here we summarize these advances and the central role of Wnt signaling, and identify the next challenges for organoid technology.

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.

Biological basis and clinical study of glycogen synthase kinase- 3β-targeted therapy by drug repositioning for glioblastoma

Background

Glycogen synthase kinase (GSK)-3β has emerged as an appealing therapeutic target for glioblastoma (GBM). Here, we investigated the therapeutic effect of the current approved drugs against GBM via inhibition of GSK3β activity both, in experimental setting and in a clinical study for recurrent GBM patients by repositioning existent drugs in combination with temozolomide (TMZ).

Materials and Methods

Progression-free and overall survival rates were compared between patients with low or high expression of active GSK3β in the primary tumor. GBM cells and a mouse model were examined for the effects of GSK3β-inhibitory drugs, cimetidine, lithium, olanzapine, and valproate. The safety and efficacy of the cocktail of these drugs (CLOVA cocktail) in combination with TMZ were tested in the mouse model and in a clinical study for recurrent GBM patients.

Results

Activation of GSK3β in the tumor inversely correlated with patient survival as an independent prognostic factor. CLOVA cocktail significantly inhibited cell invasion and proliferation. The patients treated with CLOVA cocktail in combination with TMZ showed increased survival compared to the control group treated with TMZ alone.

Conclusions

Repositioning of the GSK3β-inhibitory drugs improved the prognosis of refractory GBM patients with active GSK3β in tumors. Combination of CLOVA cocktail and TMZ is a promising approach for recurrent GBM.

Wnt/β-catenin signaling pathway inhibits the proliferation and apoptosis of U87 glioma cells via different mechanisms

The Wnt signaling pathway is necessary for the development of the central nervous system and is associated with tumorigenesis in various cancers. However, the mechanism of the Wnt signaling pathway in glioma cells has yet to be elucidated. Small-molecule Wnt modulators such as ICG-001 and AZD2858 were used to inhibit and stimulate the Wnt/β-catenin signaling pathway. Techniques including cell proliferation assay, colony formation assay, Matrigel cell invasion assay, cell cycle assay and Genechip microarray were used. Gene Ontology Enrichment Analysis and Gene Set Enrichment Analysis have enriched many biological processes and signaling pathways. Both the inhibiting and stimulating Wnt/β-catenin signaling pathways could influence the cell cycle, moreover, reduce the proliferation and survival of U87 glioma cells. However, Affymetrix expression microarray indicated that biological processes and networks of signaling pathways between stimulating and inhibiting the Wnt/β-catenin signaling pathway largely differ. We propose that Wnt/β-catenin signaling pathway might prove to be a valuable therapeutic target for glioma.

Combination Treatment with the GSK-3 Inhibitor 9-ING-41 and CCNU Cures Orthotopic Chemoresistant Glioblastoma in Patient-Derived Xenograft Models

Resistance to chemotherapy remains a major challenge in the treatment of human glioblastoma (GBM). Glycogen synthase kinase-3β (GSK-3β), a positive regulator of NF-κB–mediated survival and chemoresistance of cancer cells, has been identified as a potential therapeutic target in human GBM. Our objective was to determine the antitumor effect of GSK-3 inhibitor 9-ING-41 in combination with chemotherapy in patient-derived xenograft (PDX) models of human GBM. We utilized chemoresistant PDX models of GBM, GBM6 and GBM12, to study the effect of 9-ING-41 used alone and in combination with chemotherapy on tumor progression and survival. GBM6 and GBM12 were transfected by reporter constructs to enable bioluminescence imaging, which was used to stage animals prior to treatment and to follow intracranial GBM tumor growth. Immunohistochemical staining, apoptosis assay, and immunoblotting were used to assess the expression of GSK-3β and the effects of treatment in these models. We found that 9-ING-41 significantly enhanced 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) antitumor activity in staged orthotopic GBM12 (no response to CCNU) and GBM6 (partial response to CCNU) PDX models, as indicated by a decrease in tumor bioluminescence in mouse brain and a significant increase in overall survival. Treatment with the combination of CCNU and 9-ING-41 resulted in histologically confirmed cures in these studies. Our results demonstrate that the GSK-3 inhibitor 9-ING-41, a clinical candidate currently in Investigational New Drug (IND)-enabling development, significantly enhances the efficacy of CCNU therapy for human GBM and warrants consideration for clinical evaluation in this difficult-to-treat patient population.

Combined application of arsenic trioxide and lithium chloride augments viability reduction and apoptosis induction in human rhabdomyosarcoma cell lines

Rhabdomyosarcomas (RMS) are the most prevalent soft tissue sarcomas affecting children and adolescents. Despite intensive treatment consisting of multimodal chemotherapy and surgery RMS patients diagnosed with metastatic disease expect long term survival rates of only 20%. Often multidrug resistance arises upon initial response emphasizing the need for new therapeutic drugs to improve treatment efficiency. Previously, we demonstrated the efficacy of the FDA approved drug arsenic trioxide (ATO) specifically inhibiting viability and clonal growth as well as inducing cell death in human RMS cell lines of different subtypes. In this study, we combined low dose ATO with lithium chloride (LiCl), which is approved as mood stabilizer for the treatment of bipolar disorder, but also inhibits growth and survival of different cancer cell types in pre-clinical research. Indeed, we could show additive effects of LiCl and ATO on viability reduction, decrease of colony formation as well as cell death induction. In the course of this, LiCl induced inhibitory glycogen synthase kinase-3β (GSK-3β) serine 9 phosphorylation, whereas glioma associated oncogene family 1 (GLI1) protein expression was particularly reduced by combined ATO and LiCl treatment in RD and RH-30 cell lines, showing high rates of apoptotic cell death. These results imply that combination of ATO with LiCl or another drug targeting GSK-3 is a promising strategy to enforce the treatment efficiency in resistant and recurrent RMS.

Lithium enhances the antitumour effect of temozolomide against TP53 wild-type glioblastoma cells via NFAT1/FasL signalling

Background:

We previously showed that activation of the nuclear factor of activated T cells (NFAT)1/Fas ligand (FasL) pathway induces glioma cell death. Lithium (Li) is an inhibitor of glycogen synthase kinase (GSK)-3 that activates NFAT1/FasL signalling. Temozolomide (TMZ) inhibits GSK-3 and activates Fas in tumour protein (TP)53 wild-type (TP53wt) glioma cells. The present study investigated the combinational effects of TMZ and low-dose Li on TP53wt glioma cells.

Methods:

The combined effect of TMZ and Li was examined in TP53wt U87 and primary glioma cells and a mouse xenograft model.

Results:

Combination with 1.2 mM Li potentiated TMZ-induced cell death in TP53wt glioma cells, as determined by neurosphere formation and apoptosis assays. Temozolomide combined with Li treatment inhibited GSK-3 activation, promoted NFAT1 nuclear translocation and upregulated Fas/FasL expression. Targeted knockdown of NFAT1 expression blocked the induction of cell death by TMZ and Li via FasL inhibition. In vivo, combined treatment with TMZ and Li suppressed tumour growth and prolonged the survival of tumour-bearing mice. However, the combination of TMZ and Li did not produce a statistically significant effect in TP53mut glioma cells.

Conclusions:

Temozolomide combined with low-dose Li induces TP53wt glioma cell death via NFAT1/FasL signalling. This represents a potential therapeutic strategy for TP53wt glioma treatment.

A Metabolic Inhibitory Cocktail for Grave Cancers: Metformin, Pioglitazone and Lithium Combination in Treatment of Pancreatic Cancer and Glioblastoma Multiforme

Pancreatic cancer (PC) and glioblastoma multiforme (GBM) are among the human cancers with worst prognosis which require an urgent need for efficient therapies. Here, we propose to apply to treat both malignancies with a triple combination of drugs, which are already in use for different indications. Recent studies demonstrated a considerable link between risk of PC and diabetes. In experimental models, anti-diabetogenic agents suppress growth of PC, including metformin (M), pioglitazone (P) and lithium (L). L is used in psychiatric practice, yet also bears anti-diabetic potential and selectively inhibits glycogen synthase kinase-3 beta (GSK-3β). M, a biguanide class anti-diabetic agent shows anticancer activity via activating AMP-activated protein kinase (AMPK). Glitazones bind to PPAR-γ and inhibit NF-κB, triggering cell proliferation, apoptosis resistance and synthesis of inflammatory cytokines in cancer cells. Inhibition of inflammatory cytokines could simultaneously decrease tumor growth and alleviate cancer cachexia, having a major role in PC mortality. Furthermore, mutual synergistic interactions exist between PPAR-γ and GSK-3β, between AMPK and GSK-3β and between AMPK and PPAR-γ. In GBM, M blocks angiogenesis and migration in experimental models. Very noteworthy, among GBM patients with type 2 diabetes, usage of M significantly correlates with better survival while reverse is true for sulfonylureas. In experimental models, P synergies with ligands of RAR, RXR and statins in reducing growth of GBM. Further, usage of P was found to be lesser in anaplastic astrocytoma and GBM patients, indicating a protective effect of P against high-grade gliomas. L is accumulated in GBM cells faster and higher than in neuroblastoma cells, and its levels further increase with chronic exposure. Recent studies revealed anti-invasive potential of L in GBM cell lines. Here, we propose that a triple-agent regime including drugs already in clinical usage may provide a metabolic adjuvant therapy for PC and GBM.

Glycogen synthase kinase-3β is a pivotal mediator of cancer invasion and resistance to therapy

Tumor cell invasion and resistance to therapy are the most intractable biological characteristics of cancer and, therefore, the most challenging for current cancer research and treatment paradigms. Refractory cancers, including pancreatic cancer and glioblastoma, show an inextricable association between the highly invasive behavior of tumor cells and their resistance to chemotherapy, radiotherapy and targeted therapies. These aggressive properties of cancer share distinct cellular pathways that are connected to each other by several molecular hubs. There is increasing evidence to show that glycogen synthase kinase (GSK)‐3β is aberrantly activated in various cancer types and this has emerged as a potential therapeutic target. In many but not all cancer types, aberrant GSK3β sustains the survival, immortalization, proliferation and invasion of tumor cells, while also rendering them insensitive or resistant to chemotherapeutic agents and radiation. Here we review studies that describe associations between therapeutic stimuli/resistance and the induction of pro‐invasive phenotypes in various cancer types. Such cancers are largely responsive to treatment that targets GSK3β. This review focuses on the role of GSK3β as a molecular hub that connects pathways responsible for tumor invasion and resistance to therapy, thus highlighting its potential as a major cancer therapeutic target. We also discuss the putative involvement of GSK3β in determining tumor cell stemness that underpins both tumor invasion and therapy resistance, leading to intractable and refractory cancer with dismal patient outcomes.

miR-135b suppresses tumorigenesis in glioblastoma stem-like cells impairing proliferation, migration and self-renewal

Glioblastoma multiforme (GBM) is the most common and fatal malignant adult primary brain tumor. Currently, the overall prognosis for GBM patients remains poor despite advances in neurosurgery and adjuvant treatments. MicroRNAs (miRNAs) contribute to the pathogenesis of various types of tumor, including GBM. In this study we analyzed the expression of a panel of miRNAs, which are known to be differentially expressed by the brain and GBM tumor, in a collection of patient-derived GBM stem-like cells (GSCs). Notably, the average expression level of miR-135b, was the most downregulated compared to its normal counterpart, suggesting a potential role as anti-oncogene.

Restoration of miR-135b in GSCs significantly decreased proliferation, migration and clonogenic abilities. More importantly, miR-135b restoration was able to significantly reduce brain infiltration in mouse models of GBM obtained by intracerebral injection of GSC lines. We identified ADAM12 and confirmed SMAD5 and GSK3β as miR-135b targets and potential mediators of its effects. The whole transcriptome analysis ascertained that the expression of miR-135b downmodulated additional genes driving key pathways in GBM survival and infiltration capabilities.

Our results identify a critical role of miR-135b in the regulation of GBM development, suggesting that miR-135b might act as a tumor-suppressor factor and thus providing a potential candidate for the treatment of GBM patients.

Effects of mutations in Wnt/β-catenin, hedgehog, Notch and PI3K pathways on GSK-3 activity-Diverse effects on cell growth, metabolism and cancer

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase that participates in an array of critical cellular processes. GSK-3 was first characterized as an enzyme that phosphorylated and inactivated glycogen synthase. However, subsequent studies have revealed that this moon-lighting protein is involved in numerous signaling pathways that regulate not only metabolism but also have roles in: apoptosis, cell cycle progression, cell renewal, differentiation, embryogenesis, migration, regulation of gene transcription, stem cell biology and survival. In this review, we will discuss the roles that GSK-3 plays in various diseases as well as how this pivotal kinase interacts with multiple signaling pathways such as: PI3K/PTEN/Akt/mTOR, Ras/Raf/MEK/ERK, Wnt/beta-catenin, hedgehog, Notch and TP53. Mutations that occur in these and other pathways can alter the effects that natural GSK-3 activity has on regulating these signaling circuits that can lead to cancer as well as other diseases. The novel roles that microRNAs play in regulation of the effects of GSK-3 will also be evaluated. Targeting GSK-3 and these other pathways may improve therapy and overcome therapeutic resistance.

The peroxisome proliferator activated receptor gamma agonist pioglitazone increases functional expression of the glutamate transporter excitatory amino acid transporter 2 (EAAT2) in human glioblastoma cells

Glioma cells release glutamate through expression of system xc-, which exchanges intracellular glutamate for extracellular cysteine. Lack of the excitatory amino acid transporter 2 (EAAT2) expression maintains high extracellular glutamate levels in the glioma microenvironment, causing excitotoxicity to surrounding parenchyma. Not only does this contribute to the survival and proliferation of glioma cells, but is involved in the pathophysiology of tumour-associated epilepsy (TAE). We investigated the role of the peroxisome proliferator activated receptor gamma (PPARγ) agonist pioglitazone in modulating EAAT2 expression in glioma cells. We found that EAAT2 expression was increased in a dose dependent manner in both U87MG and U251MG glioma cells. Extracellular glutamate levels were reduced with the addition of pioglitazone, where statistical significance was reached in both U87MG and U251MG cells at a concentration of ≥ 30 μM pioglitazone (p < 0.05). The PPARγ antagonist GW9662 inhibited the effect of pioglitazone on extracellular glutamate levels, indicating PPARγ dependence. In addition, pioglitazone significantly reduced cell viability of U87MG and U251MG cells at ≥ 30 μM and 100 μM (p < 0.05) respectively. GW9662 also significantly reduced viability of U87MG and U251MG cells with 10 μM and 30 μM (p < 0.05) respectively. The effect on viability was partially dependent on PPARγ activation in U87MG cells but not U251MG cells, whereby PPARγ blockade with GW9662 had a synergistic effect. We conclude that PPARγ agonists may be therapeutically beneficial in the treatment of gliomas and furthermore suggest a novel role for these agents in the treatment of tumour associated seizures through the reduction in extracellular glutamate.

Glycogen synthase kinase 3β dictates podocyte motility and focal adhesion turnover by modulating paxillin activity: implications for the protective effect of low-dose lithium in podocytopathy

Aberrant focal adhesion turnover is centrally involved in podocyte actin cytoskeleton disorganization and foot process effacement. The structural and dynamic integrity of focal adhesions is orchestrated by multiple cell signaling molecules, including glycogen synthase kinase 3β (GSK3β), a multitasking kinase lately identified as a mediator of kidney injury. However, the role of GSK3β in podocytopathy remains obscure. In doxorubicin (Adriamycin)-injured podocytes, lithium, a GSK3β inhibitor and neuroprotective mood stabilizer, obliterated the accelerated focal adhesion turnover, rectified podocyte hypermotility, and restored actin cytoskeleton integrity. Mechanistically, lithium counteracted the doxorubicin-elicited GSK3β overactivity and the hyperphosphorylation and overactivation of paxillin, a focal adhesion-associated adaptor protein. Moreover, forced expression of a dominant negative kinase dead mutant of GSK3β highly mimicked, whereas ectopic expression of a constitutively active GSK3β mutant abolished, the effect of lithium in doxorubicin-injured podocytes, suggesting that the effect of lithium is mediated, at least in part, through inhibition of GSK3β. Furthermore, paxillin interacted with GSK3β and served as its substrate. In mice with doxorubicin nephropathy, a single low dose of lithium ameliorated proteinuria and glomerulosclerosis. Consistently, lithium therapy abrogated GSK3β overactivity, blunted paxillin hyperphosphorylation, and reinstated actin cytoskeleton integrity in glomeruli associated with an early attenuation of podocyte foot process effacement. Thus, GSK3β-modulated focal adhesion dynamics might serve as a novel therapeutic target for podocytopathy.

Lithium inhibits tumor lymphangiogenesis and metastasis through the inhibition of TGFBIp expression in cancer cells

Metastasis is the main cause of mortality in cancer patients. Although there are many anti-cancer drugs targeting tumor growth, anti-metastatic agents are rarely developed. Angiogenesis and lymphangiogenesis are crucial for cancer progression; in particular, lymphangiogenesis is pivotal for metastasis in cancer. Here we report that lithium inhibits colon cancer metastasis by blocking lymphangiogenesis. Lithium reduces the expression of transforming growth factor-β-induced protein (TGFBIp) in colon cancer cells by inhibiting Smad3 phosphorylation via GSK3β inactivation. Moreover, lithium inhibits lymphatic endothelial cell migration, which is increased upon TGFBIp expression in tumor cells. Lithium had no significant effect on SW620 tumor growth in vitro and in vivo; however, it inhibited lymphangiogenesis in tumors. In tumor xenografts model, lithium was found to prevent metastasis to the lungs, liver, and lymph nodes by inhibiting TGFBIp-induced tumor lymphangiogenesis. Collectively, our findings demonstrate a novel role of lithium in the inhibition of colon cancer metastasis by blocking TGFBIp expression, and thereby TGFBIp-induced lymphangiogenesis, in primary tumors.

BKM-120 (Buparlisib): A Phosphatidyl-Inositol-3 Kinase Inhibitor with Anti-Invasive Properties in Glioblastoma

Glioblastoma is an aggressive, invasive tumor of the central nervous system (CNS). There is a widely acknowledged need for anti-invasive therapeutics to limit glioblastoma invasion. BKM-120 is a CNS-penetrant pan-class I phosphatidyl-inositol-3 kinase (PI3K) inhibitor in clinical trials for solid tumors, including glioblastoma. We observed that BKM-120 has potent anti-invasive effects in glioblastoma cell lines and patient-derived glioma cells in vitro. These anti-migratory effects were clearly distinguishable from cytostatic and cytotoxic effects at higher drug concentrations and longer durations of drug exposure. The effects were reversible and accompanied by changes in cell morphology and pronounced reduction in both cell/cell and cell/substrate adhesion. In vivo studies showed that a short period of treatment with BKM-120 slowed tumor spread in an intracranial xenografts. GDC-0941, a similar potent and selective PI3K inhibitor, only caused a moderate reduction in glioblastoma cell migration. The effects of BKM-120 and GDC-0941 were indistinguishable by in vitro kinase selectivity screening and phospho-protein arrays. BKM-120 reduced the numbers of focal adhesions and the velocity of microtubule treadmilling compared with GDC-0941, suggesting that mechanisms in addition to PI3K inhibition contribute to the anti-invasive effects of BKM-120. Our data suggest the CNS-penetrant PI3K inhibitor BKM-120 may have anti-invasive properties in glioblastoma.