Downregulation of Krüppel-like factor 14 accelerated cellular senescence and aging.

Aging has been considered as a risk factor in many diseases, thus, comprehensively understanding the cellular and molecular mechanisms of delayed aging is important. Here we investigated whether Krüppel-like factor 14 (KLF14) is a suppressor of cellular senescence and aging. In our research, KLF14 levels significantly decreased not only in the lymphocytes of healthy people but also in the cells and tissues of mice with aging. We performed in vitro and in vivo experiments on cells and mice to reveal the function of KLF14 in aging. KLF14 deficiency facilitates cellular senescence and aging-related pathologies in C57BL/6J mice, whereas KLF14 overexpression attenuates cellular senescence. Mechanistically, KLF14 delays aging by binding to the POLD1 promoter to positively regulate POLD1 expression. Remarkably, cellular senescence mediated by KLF14 downregulation could be alleviated by POLD1 expression. In addition, perhexiline, an agonist of KLF14, could delay cellular senescence and aging-related pathologies in senescence-accelerated P8 mice by inducing POLD1 expression, as perhexiline could enhance the effect of KLF14's transcription activation to POLD1 by elevating the binding level of KLF14 to the POLD1 promoter. Our data indicate that KLF14 might be a critical element in aging by upregulating POLD1 expression, indicating that the activation of KLF14 may delay aging and aging-associated diseases.

Bacterial Outer Membrane Vesicles Loaded with Perhexiline Suppress Tumor Development by Regulating Tumor-Associated Macrophages Repolarization in a Synergistic Way.

Tumor-associated macrophages (TAMs) promote tumor development and metastasis and are categorized into M1-like macrophages, suppressing tumor cells, and M2-like macrophages. M2-like macrophages, occupying a major role in TAMs, can be repolarized into anti-tumoral phenotypes. In this study, outer membrane vesicles (OMVs) secreted by Escherichia coli Nissle 1917 carry perhexiline (OMV@Perhx) to explore the influence of OMVs and perhexiline on TAM repolarization. OMV@Perhx was internalized by macrophages and regulated the phenotype of TAMs from M2-like to M1-like efficiently to increase the level of tumor suppressor accordingly. Re-polarized macrophages promoted apoptosis and inhibited the mobility of tumor, cells including invasion and migration. The results indicate that OMVs improve the efficacy of perhexiline and also represent a promising natural immunomodulator. Combining OMVs with perhexiline treatments shows powerfully synergistic anti-tumor effects through co-culturing with re-polarized macrophages. This work is promising to exploit the extensive applications of OMVs and chemical drugs, therefore developing a meaningful drug carrier and immunomodulator as well as expanding the purposes of traditional chemical drugs.

Perhexiline: Old Drug, New Tricks? A Summary of Its Anti-Cancer Effects.

Cancer metabolic plasticity, including changes in fatty acid metabolism utilisation, is now widely appreciated as a key driver for cancer cell growth, survival and malignancy. Hence, cancer metabolic pathways have been the focus of much recent drug development. Perhexiline is a prophylactic antianginal drug known to act by inhibiting carnitine palmitoyltransferase 1 (CPT1) and 2 (CPT2), mitochondrial enzymes critical for fatty acid metabolism. In this review, we discuss the growing evidence that perhexiline has potent anti-cancer properties when tested as a monotherapy or in combination with traditional chemotherapeutics. We review the CPT1/2 dependent and independent mechanisms of its anti-cancer activities. Finally, we speculate on the clinical feasibility and utility of repurposing perhexiline as an anti-cancer agent, its limitations including known side effects and its potential added benefit of limiting cardiotoxicity induced by other chemotherapeutics.

Proteomic characterisation of perhexiline treatment on THP-1 M1 macrophage differentiation.

Background: Dysregulated inflammation is important in the pathogenesis of many diseases including cancer, allergy, and autoimmunity. Macrophage activation and polarisation are commonly involved in the initiation, maintenance and resolution of inflammation. Perhexiline (PHX), an antianginal drug, has been suggested to modulate macrophage function, but the molecular effects of PHX on macrophages are unknown. In this study we investigated the effect of PHX treatment on macrophage activation and polarization and reveal the underlying proteomic changes induced. Methods: We used an established protocol to differentiate human THP-1 monocytes into M1 or M2 macrophages involving three distinct, sequential stages (priming, rest, and differentiation). We examined the effect of PHX treatment at each stage on the polarization into either M1 or M2 macrophages using flow cytometry, quantitative polymerase chain reaction (qPCR) and enzyme linked immunosorbent assay (ELISA). Quantitative changes in the proteome were investigated using data independent acquisition mass spectrometry (DIA MS). Results: PHX treatment promoted M1 macrophage polarization, including increased STAT1 and CCL2 expression and IL-1ß secretion. This effect occurred when PHX was added at the differentiation stage of the M1 cultures. Proteomic profiling of PHX treated M1 cultures identified changes in metabolic (fatty acid metabolism, cholesterol homeostasis and oxidative phosphorylation) and immune signalling (Receptor Tyrosine Kinase, Rho GTPase and interferon) pathways. Conclusion: This is the first study to report on the action of PHX on THP-1 macrophage polarization and the associated changes in the proteome of these cells.

Study of the roles of cytochrome P450 (CYPs) in the metabolism and cytotoxicity of perhexiline.

Perhexiline is a prophylactic antianginal agent developed in the 1970s. Although, therapeutically, it remained a success, the concerns of its severe adverse effects including hepatotoxicity caused the restricted use of the drug, and eventually its withdrawal from the market in multiple countries. In the clinical setting, cytochrome P450 (CYP) 2D6 is considered as a possible risk factor for the adverse effects of perhexiline. However, the role of CYP-mediated metabolism in the toxicity of perhexiline, particularly in the intact cells, remains unclear. Using our previously established HepG2 cell lines that individually express 14 CYPs (1A1, 1A2, 1B1, 2A6, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, 3A4, 3A5, and 3A7) and human liver microsomes, we identified that CYP2D6 plays a major role in the hydroxylation of perhexiline. We also determined that CYP1A2, 2C19, and 3A4 contribute to the metabolism of perhexiline. The toxic effect of perhexiline was reduced significantly in CYP2D6-overexpressing HepG2 cells, in comparison to the control cells. In contrast, overexpression of CYP1A2, 2C19, and 3A4 did not show a significant protective effect against the toxicity of perhexiline. Pre-incubation with quinidine, a well-recognized CYP2D6 inhibitor, significantly attenuated the protective effect in CYP2D6-overexpressing HepG2 cells. Furthermore, perhexiline-induced mitochondrial damage, apoptosis, and ER stress were also attenuated in CYP2D6-overexpressing HepG2 cells. These findings suggest that CYP2D6-mediated metabolism protects the cells from perhexiline-induced cytotoxicity and support the clinical observation that CYP2D6 poor metabolizers may have higher risk for perhexiline-induced hepatotoxicity.

Refractory angina is a growing challenge for palliative medicine: a systematic review of non-invasive interventions.

BACKGROUND: Refractory angina can have a significant effect on quality of life. Non-invasive interventions have been suggested but there are few guidelines on management. Our aim was to systematically review all studies that reported non-invasive interventions for refractory angina and report on their effectiveness and safety. METHODS: We performed a literature search of six databases and a grey literature search. Treatments considered first line or second line according to the European Society of Cardiology were excluded, as were interventions that had undergone review within the last 3 years. Design, setting and outcomes were extracted and quality was assessed. A narrative synthesis was undertaken, including an analysis of adverse effects. RESULTS: 4476 studies were screened, 14 studies were included in our analysis. Interventions were specialist multidisciplinary programmes, transcutaneous electrical nerve stimulation (TENS), perhexiline, medical optimisation, morphine and intranasal alfentanil. The effects of specialist programmes and perhexiline treatment were mixed. Positive effects were reported with TENS, opioids and medical optimisation, with improvements in symptoms, exercise capacity and quality of life. No major adverse effects were noted in any of the treatments. CONCLUSION: There are non-invasive treatments for refractory angina that are overlooked by current guidelines. While the quality of these studies varies, positive changes have been reported in symptoms, exercise tolerance and quality of life with few adverse effects. There is a need for further research into these treatments which could be useful within the contexts of cardiology and palliative care.

Electrophysiological and ECG Effects of Perhexiline, a Mixed Cardiac Ion Channel Inhibitor, Evaluated in Nonclinical Assays and in Healthy Subjects.

Perhexiline has been used to treat hypertrophic cardiomyopathy. In addition to its effect on carnitine-palmitoyltransferase-1, it has mixed ion channel effects through inhibition of several cardiac ion currents. Effects on cardiac ion channels expressed in mammalian cells were assayed using a manual patch-clamp technique, action potential duration (APD) was measured in ventricular trabeculae of human donor hearts, and electrocardiogram effects were evaluated in healthy subjects in a thorough QT (TQT) study. Perhexiline blocked several cardiac ion currents at concentrations within the therapeutic range (150-600 ng/mL) with IC50 for hCav1.2 ∼ hERG < late hNav1.5. A significant APD shortening was observed in perhexiline-treated cardiomyocytes. The TQT study was conducted with a pilot part in 9 subjects to evaluate a dosing schedule that would achieve therapeutic and supratherapeutic perhexiline plasma concentrations on days 4 and 6, respectively. Guided by the results from the pilot, 104 subjects were enrolled in a parallel-designed part with a nested crossover comparison for the positive control. Perhexiline caused QTc prolongation, with the largest effect on ΔΔQTcF, 14.7 milliseconds at therapeutic concentrations and 25.6 milliseconds at supratherapeutic concentrations and a positive and statistically significant slope of the concentration-ΔΔQTcF relationship (0.018 milliseconds per ng/mL; 90%CI, 0.0119-0.0237 milliseconds per ng/mL). In contrast, the JTpeak interval was shortened with a negative concentration-JTpeak relationship, a pattern consistent with multichannel block. Further studies are needed to evaluate whether this results in a low proarrhythmic risk.

Randomized controlled trial of perhexiline on regression of left ventricular hypertrophy in patients with symptomatic hypertrophic cardiomyopathy (RESOLVE-HCM trial).

BACKGROUND: The presence and extent of left ventricular hypertrophy (LVH) is a major determinant of symptoms in patients with hypertrophic cardiomyopathy (HCM). There is increasing evidence to suggest that myocardial energetic impairment represents a central mechanism leading to LVH in HCM. There is currently a significant unmet need for disease-modifying therapy that regresses LVH in HCM patients. Perhexiline, a potent carnitine palmitoyl transferase-1 (CPT-1) inhibitor, improves myocardial energetics in HCM, and has the potential to reduce LVH in HCM. OBJECTIVE: The primary objective is to evaluate the effects of perhexiline treatment on the extent of LVH, in symptomatic HCM patients with at least moderate LVH. METHODS/DESIGN: RESOLVE-HCM is a prospective, multicenter double-blind placebo-controlled randomized trial enrolling symptomatic HCM patients with at least moderate LVH. Sixty patients will be randomized to receive either perhexiline or matching placebo. The primary endpoint is change in LVH, assessed utilizing cardiovascular magnetic resonance (CMR) imaging, after 12-months treatment with perhexiline. SUMMARY: RESOLVE-HCM will provide novel information on the utility of perhexiline in regression of LVH in symptomatic HCM patients. A positive result would lead to the design of a Phase 3 clinical trial addressing long-term effects of perhexiline on risk of heart failure and mortality in HCM patients.

Perhexiline treatment improves toxic effects of ß-adrenergic receptor stimulation in experimental peripartum cardiomyopathy.

AIMS: Peripartum cardiomyopathy (PPCM) is a pregnancy-associated cardiomyopathy that occurs in previously heart-healthy women towards the end of pregnancy or in the first months after delivery and is characterized by heart failure due to systolic dysfunction. The clinical course of PPCM differs between mild symptoms and severe forms with acute heart failure complicated by cardiogenic shock (CS). Treatment of CS complicating PPCM is challenging, as ß-adrenergic receptor (ß-AR) stimulation seems to be associated with progression of heart failure and adverse outcome. This experimental study aims to examine whether postpartum treatment with the glucose uptake-promoting drug perhexiline alone or as co-treatment with ß-AR stimulation prevents heart failure in the experimental PPCM mouse model. METHODS AND RESULTS: Postpartum (PP) female PPCM-prone mice with a cardiomyocyte-restricted STAT3-deficiency (αMHC-Cretg/+ ;Stat3fl/fl ; CKO) were treated with perhexiline over two to three pregnancies and nursing periods (2/3PP) or were co-treated with perhexiline after one pregnancy (1PP) under chronic ß-AR stimulation using isoproterenol (Iso) infusion. Perhexiline was not able to prevent onset of PPCM in CKO mice (FS: CKO Pexsig-2/3PP: 25 ± 12% vs. CKO Ctrl-2/3PP: 24 ± 9%, n.s.) but attenuated worsening of left ventricular function in response to treatment with the ß-AR agonist Iso (FS: CKO Pexsig-Iso-1PP: 19 ± 4% vs. CKO Ctrl-Iso-1PP: 11 ± 5%, P < 0.05). CONCLUSIONS: Treatment of PPCM patients with ß-AR agonists should be avoided whenever possible. In cases with CS complicating PPCM, when treatment with ß-AR agonists cannot be prevented, co-medication with perhexiline might help to reduce the cardiotoxic side effects of ß-AR stimulation. Clinical data are necessary to further validate this therapeutic approach.

Identification of hit compounds with anti-schistosomal activity on in vitro generated juvenile worms in cell-free medium.

BACKGROUND: Anthelminthic treatment options against schistosomiasis are limited. The current treatment relies almost exclusively on a single drug, praziquantel (PZQ). As a consequence, the development of resistance to PZQ and limited activity of PZQ against earlier development stages are respectively a risk and a limitation to achieving the goals of the new WHO roadmap towards elimination. For the discovery of new chemical starting points, the in vitro drug screening on Schistosoma mansoni (S. mansoni) against newly transformed schistosomula (NTS) is still the most predominant approach. The use of only NTS in the initial screening limits sensitivity to potential new compounds which are predominantly active in later developmental stages. Using our recently described highly standardized, straightforward and reliable culture method that generates high rates of juvenile worms, we aimed to repurpose a subset of the National Center for Advancing Translational Sciences (NCATS) Pharmaceutical Collection (340 compounds) to identify new hits with an in vitro worm culture assay. METHODOLOGY/PRINCIPAL FINDINGS: Cercariae were mechanically transformed into skin-stage (SkS) schistosomula and continuously cultured for 3-6 weeks to the liver stage (LiS). A commercial source of serum was identified, and decrease of NTS/well along with optimal drug testing conditions was established to test compounds on early and late LiS worms. The library was screened in 96-well format assays using praziquantel (PZQ) as a positive control. Primary screening allowed a 5.9% hit rate and generated two confirmed hits on adult worms; a prophylactic antianginal agent and an antihistaminic drug. CONCLUSION: With this standardized and reliable in vitro assay, important S. mansoni developmental stages up to LiS worms can be generated and cultured over an extended period. When exposed to a subset of the NCATS Pharmaceutical Collection, 3 compounds yielded a defined anti-schistosomal phenotype on juvenile worms. Translation of activity on perfused adult S. mansoni worms was achieved only for perhexiline (a prophylactic antianginal agent) and astemizole (an antihistaminic drug).

Optic neuropathy secondary to perhexiline and amiodarone.

Bilateral optic disc swelling is an important clinical sign for potentially life-threatening and sight-threatening conditions, with the most common being raised intracranial pressure and pseudopapillitis. Perhexiline-related and amiodarone-related optic disc swellings are diagnoses of exclusion. This report describes the diagnosis of a man with perhexiline-induced and amiodarone-induced optic neuropathy after extensive investigation consisting of full ophthalmic examination, biochemical screen, temporal artery biopsy, CT, MRI, positron emission tomography and lumbar puncture. There was partial to complete resolution of optic neuropathy following cessation of the causative medication. We postulate that the underlying mechanism of perhexiline toxicity could be mitochondrial dysfunction related. Our case demonstrates that patients treated with perhexiline and amiodarone should be monitored closely for ocular side effects.

A mechanism of perhexiline's cytotoxicity in hepatic cells involves endoplasmic reticulum stress and p38 signaling pathway.

Perhexiline is a coronary vasodilator for angina treatment that was first developed in the 1960s. Perhexiline enjoyed worldwide success before reports of severe side effects, such as hepatotoxicity and neurotoxicity, caused its withdrawal from most of the markets. The underlying mechanism of the cytotoxicity of perhexiline, however, is not yet well understood. Here we demonstrated that perhexiline induced cellular damage in primary human hepatocytes, HepaRG cells and HepG2 cells. Analysis of gene and protein expression levels of endoplasmic reticulum (ER) stress markers showed that perhexiline caused ER stress in primary human hepatocytes and HepG2 cells. The splicing of XBP1 mRNA, a hallmark of ER stress, was observed upon perhexiline treatment. Using Gluc-Fluc-HepG2 cell line, we demonstrated that protein secretion was impaired upon perhexiline treatment, suggesting functional deficits in ER. Inhibition of ER stress using ER inhibitor 4-PBA or salubrinal attenuated the cytotoxicity of perhexiline. Directly knocking down ATF4 using siRNA also partially rescued HepG2 cells upon perhexiline exposure. In addition, inhibition of ER stress using either inhibitors or siRNA transfection attenuated perhexiline-induced increase in caspase 3/7 activity, indicating that ER stress contributed to perhexiline-induced apoptosis. Moreover, perhexiline treatment resulted in activation of p38 and JNK signaling pathways, two branches of MAPK cascade. Pre-treating HepG2 cells with p38 inhibitor SB239063 attenuated perhexiline-induced apoptosis and cell death. The inhibitor also prevented the activation of CHOP and ATF4. Overall, our study demonstrated that ER stress is one important mechanism underlying the hepatotoxicity of perhexiline, and p38 signaling pathway contributes to this process. Our finding shed light on the role of both ER stress and p38 signaling pathway in drug-induced liver injury.

Drug effects on metabolic profiles of Schistosoma mansoni adult male parasites detected by 1H-NMR spectroscopy.

Schistosomiasis is one of the most devastating neglected tropical parasitic diseases caused by trematodes of the genus Schistosoma. Praziquantel (PZQ) is today the only drug used in humans and animals for the treatment of schistosomiasis but unfortunately it is poorly effective on larval and juvenile stages of the parasite. Therefore, it is urgent the discovery of new drug targets and compounds. We have recently showed that the anti-anginal drug perhexiline maleate (PHX) is very active on multiple developmental stages of Schistosoma mansoni in vitro. It is well known that PHX impacts the lipid metabolism in mammals, but the final target on schistosomes still remains unknown. The aim of this study was to evaluate the ability of 1H nuclear magnetic resonance (NMR) spectroscopy in revealing metabolic perturbations due to PHX treatment of S. mansoni adult male worms. The effects of PHX were compared with the ones induced by vehicle and gambogic acid, in order to detect different metabolic profiles and specificity of the PHX action. Remarkably a list of metabolites associated to PHX-treatment was identified with enrichment in several connected metabolic pathways including also the Kennedy pathway mediating the glycerophospholipid metabolism. Our study represents the first 1H-NMR metabolomic approach to characterize the response of S. mansoni to drug treatment. The obtained "metabolic fingerprint" associated to PHX treatment could represent a strategy for displaying cellular metabolic changes for any given drug and to compare compounds targeting similar or distinct biochemical pathways.

Mitochondrial dysfunction and apoptosis underlie the hepatotoxicity of perhexiline.

Perhexiline is an anti-anginal drug developed in the late 1960s. Despite its therapeutic success, it caused severe hepatoxicity in selective patients, which resulted in its withdrawal from the market. In the current study we explored the molecular mechanisms underlying the cytotoxicity of perhexiline. In primary human hepatocytes, HepaRG cells, and HepG2 cells, perhexiline induced cell death in a concentration- and time-dependent manner. Perhexiline treatment also caused a significant increase in caspase 3/7 activity at 2 h and 4 h. Pretreatment with specific caspase inhibitors suggested that both intrinsic and extrinsic apoptotic pathways contributed to perhexiline-induced cytotoxicity, which was confirmed by increased expression of TNF-α, cleavage of caspase 3 and 9 upon perhexiline treatment. Moreover, perhexiline caused mitochondrial dysfunction, demonstrated by the classic glucose-galactose assay at 4 h and 24 h. Results from JC-1 staining suggested perhexiline caused loss of mitochondrial potential. Blocking mitochondrial permeability transition pore using inhibitor bongkrekic acid attenuated the cytotoxicity of perhexiline. Western blotting analysis also showed decreased expression level of pro-survival proteins Bcl-2 and Mcl-1, and increased expression of pro-apoptotic protein Bad. Direct measurement of the activity of individual components of the mitochondrial respiratory complex demonstrated that perhexiline strongly inhibited Complex IV and Complex V and moderately inhibited Complex II and Complex II + III. Overall, our data demonstrated that both mitochondrial dysfunction and apoptosis underlies perhexiline-induced hepatotoxicity.

(+)-(R)- and (-)-(S)-Perhexiline maleate: Enantioselective synthesis and functional studies on Schistosoma mansoni larval and adult stages.

Schistosomiasis is a neglected tropical disease mainly affecting the poorest tropical and subtropical areas of the world with the impressive number of roughly 200 million infections per year. Schistosomes are blood trematode flukes of the genus Schistosoma causing symptoms in humans and animals. Organ morbidity is caused by the accumulation of parasite eggs and subsequent development of fibrosis. If left untreated, schistosomiasis can result in substantial morbidity and even mortality. Praziquantel (PZQ) is the most effective and widely used compound for the treatment of the disease, in prevention and control programs in the last 30 years. Unfortunately, it has no effect on juvenile immature schistosomes and cannot prevent reinfection or interfere with the schistosome life cycle; moreover drug-resistance represents a serious threat. The search for an alternative or complementary treatment is urgent and drug repurposing could accelerate a solution. The anti-anginal drug perhexiline maleate (PHX) has been previously shown to be effective on larval, juvenile, and adult stages of S. mansoni and to impact egg production in vitro. Since PHX is a racemic mixture of R-(+)- and S-(-)-enantiomers, we designed and realized a stereoselective synthesis of both PHX enantiomers and developed an analytical procedure for the direct quantification of the enantiomeric excess also suitable for semipreparative separation of PHX enantiomers. We next investigated the impact of each enantiomer on viability of newly transformed schistosomula (NTS) and worm pairs of S. mansoni as well as on egg production and vitellarium morphology by in vitro studies. Our results indicate that the R-(+)-PHX is mainly driving the anti-schistosomal activity but that also the S-(-)-PHX possesses a significant activity towards S. mansoni in vitro.

Perhexiline Demonstrates FYN-mediated Antitumor Activity in Glioblastoma.

Glioblastoma is the most common primary malignant brain tumor in adults. Despite aggressive treatment, outcomes remain poor with few long-term survivors. Therefore, considerable effort is being made to identify novel therapies for this malignancy. Targeting tumor metabolism represents a promising therapeutic strategy and activation of fatty acid oxidation (FAO) has been identified as a central metabolic node contributing toward gliomagenesis. Perhexiline is a compound with a long clinical track record in angina treatment and commonly described as an FAO inhibitor. We therefore sought to determine whether this compound might be repurposed to serve as a novel therapy in glioblastoma. Perhexiline demonstrated potent in vitro cytotoxicity, induction of redox stress and apoptosis in a panel of glioblastoma cell lines. However, the antitumor activity of perhexiline was distinct when compared with the established FAO inhibitor etomoxir. By evaluating mitochondrial respiration and lipid dynamics in glioblastoma cells following treatment with perhexiline, we confirmed this compound did not inhibit FAO in our models. Using in silico approaches, we identified FYN as a probable target of perhexiline and validated the role of this protein in perhexiline sensitivity. We extended studies to patient samples, validating the potential of FYN to serve as therapeutic target in glioma. When evaluated in vivo, perhexiline demonstrated the capacity to cross the blood-brain barrier and antitumor activity in both flank and orthotopic glioblastoma models. Collectively, we identified potent FYN-dependent antitumor activity of perhexiline in glioblastoma, thereby, representing a promising agent to be repurposed for the treatment of this devastating malignancy.

Inhibition of fatty acid catabolism augments the efficacy of oxaliplatin-based chemotherapy in gastrointestinal cancers.

Gastrointestinal cancer causes countless deaths every year due to therapeutic resistance. However, whether metabolic alterations contribute to chemoresistance is not well understood. In this study, we report that fatty acid (FA) catabolism was activated in gastrointestinal cancer cells treated with oxaliplatin, which exhibited higher expression of the rate-limiting enzymes carnitine palmitoyltransferase 1B (CPT1B) and CPT2. The clinical analysis also showed that high expression of these enzymes was associated with poor oxaliplatin-based chemotherapy outcomes in patients. Furthermore, genetic or pharmacological inhibition of CPT2 with perhexiline disturbed NADPH and redox homeostasis and increased reactive oxygen species (ROS) generation and cell apoptosis in gastrointestinal cancer cells following oxaliplatin treatment. Specifically, the combination of oxaliplatin and perhexiline significantly suppressed the progression of gastrointestinal cancer in cell-based xenograft and patient-derived xenograft (PDX) models. Mechanistically, CPT2 was transcriptionally upregulated by nuclear factor of activated T cells 3 (NFATc3), which translocated to the nucleus in response to oxaliplatin treatment. In summary, our study suggests that the inhibition of CPT-mediated FA catabolism combined with conventional chemotherapy is a promising therapeutic strategy for patients with gastrointestinal cancers.

A Tumor Agnostic Therapeutic Strategy for Hexokinase 1-Null/Hexokinase 2-Positive Cancers.

Since Warburg's observation that most cancers exhibit elevated glycolysis, decades of research have attempted to reduce tumor glucose utilization as a therapeutic approach. Hexokinase (HK) activity is the first glycolytic enzymatic step; despite many attempts to inhibit HK activity, none has reached clinical application. Identification of HK isoforms, and recognition that most tissues express only HK1 while most tumors express HK1 and HK2, stimulated reducing HK2 activity as a therapeutic option. However, studies using HK2 shRNA and isogenic HK1+HK2- and HK1+HK2+ tumor cell pairs demonstrated that tumors expressing only HK1, while exhibiting reduced glucose consumption, progressed in vivo as well as tumors expressing both HK1 and HK2. However, HK1-HK2+ tumor subpopulations exist among many cancers. shRNA HK2 suppression in HK1-HK2+ liver cancer cells reduced xenograft tumor progression, in contrast to HK1+HK2+ cells. HK2 inhibition, and partial inhibition of both oxidative phosphorylation and fatty acid oxidation using HK2 shRNA and small-molecule drugs, prevented human liver HK1-HK2+ cancer xenograft progression. Using human multiple myeloma xenografts and mouse allogeneic models to identify potential clinical translational agents, triple therapies that include antisense HK2 oligonucleotides, metformin, and perhexiline prevent progression. These results suggest an agnostic approach for HK1-HK2+ cancers, regardless of tissue origin.

Enantioselectivity in the tissue distribution of perhexiline contributes to different effects on hepatic histology and peripheral neural function in rats.

Perhexiline, a chiral drug, is a potent antiischemic agent whose clinical utility is limited by hepatic and neural toxicities. It inhibits mitochondrial carnitine palmitoyltransferase-1, however, excessive inhibition predisposes toward tissue steatosis. This pilot study investigated the distribution of the two enantiomers and their toxicological potential. Dark Agouti rats (n = 4 per group) were administered vehicle or 200 mg/kg daily of racemic, (+)- or (-)-perhexiline maleate orally for 8 weeks. Plasma biochemical liver function tests and Von Frey assessments of peripheral neural function were performed. Hepatic and neuronal histology, including lipid and glycogen content, was assessed using electron microscopy. Concentrations of the perhexiline enantiomers and metabolites were quantified in plasma, liver and heart. Plasma perhexiline concentrations following administration of racemate, (+)- or (-)-enantiomer were within the mid-upper clinical therapeutic range. There was extensive uptake of both enantiomers into liver and heart, with 2.5- to 4.5-fold greater net uptake of (+)- compared to (-)-perhexiline (P < .05) when administered as pure enantiomers, but not when administered as racemate. There was no biochemical or gross histological evidence of hepatotoxicity. However, livers of animals administered (+)-perhexiline had higher lipid (P < .01) and lower glycogen (P < .05) content, compared to those administered (-)-perhexiline. Animals administered racemic perhexiline had reduced peripheral neural function (P < .05) compared to controls or animals administered (-)-perhexiline. For the same plasma concentrations, differences in tissue distribution may contribute to disparities in the effects of (+)- and (-)-perhexiline on hepatic histology and neural function.

Carnitine palmitoyltransferase gene upregulation by linoleic acid induces CD4+ T cell apoptosis promoting HCC development.

Hepatocellular carcinoma (HCC) is a common cause of cancer-related death worldwide. As obesity and diabetes become more prevalent, the contribution of non-alcoholic fatty liver disease (NAFLD) to HCC is rising. Recently, we reported intrahepatic CD4+ T cells are critical for anti-tumor surveillance in NAFLD. Lipid accumulation in the liver is the hallmark of NAFLD, which may perturb T cell function. We sought to investigate how the lipid-rich liver environment influences CD4+ T cells by focusing on carnitine palmitoyltransferase (CPT) family members, which control the mitochondrial ß-oxidation of fatty acids and act as key molecules in lipid catabolism. Linoleic acid (C18:2) co-localized within the mitochondria along with a corresponding increase in CPT gene upregulation. This CPT upregulation can be recapitulated by feeding mice with a high-C18:2 diet or the NAFLD promoting methionine-choline-deficient (MCD) diet. Using an agonist and antagonist, the induction of CPT genes was found to be mediated by peroxisome proliferator-activated receptor alpha (PPAR-α). CPT gene upregulation increased mitochondrial reactive oxygen species (ROS) and led to cell apoptosis. In vivo, using liver-specific inducible MYC transgenic mice fed MCD diet, blocking CPT with the pharmacological inhibitor perhexiline decreased apoptosis of intrahepatic CD4+ T cells and inhibited HCC tumor formation. These results provide useful information for potentially targeting the CPT family to rescue intrahepatic CD4+ T cells and to aid immunotherapy for NAFLD-promoted HCC.