Effect of capsazepine on cytosolic Ca2+ levels and proliferation of human prostate cancer cells

Transient receptor potential vanilloid 1 (TRPV1)-independent actions of capsaicin on cellular excitability and ion transport

Capsaicin is a naturally occurring alkaloid derived from chili pepper that is responsible for its hot pungent taste. Capsaicin is known to exert multiple pharmacological actions, including analgesia, anticancer, anti-inflammatory, antiobesity, and antioxidant effects. The transient receptor potential vanilloid subfamily member 1 (TRPV1) is the main receptor mediating the majority of the capsaicin effects. However, numerous studies suggest that the TRPV1 receptor is not the only target for capsaicin. An increasing number of studies indicates that capsaicin, at low to mid µM ranges, not only indirectly through TRPV1-mediated Ca²⁺ increases, but also directly modulates the functions of voltage-gated Na⁺ , K⁺ , and Ca²⁺ channels, as well as ligand-gated ion channels and other ion transporters and enzymes involved in cellular excitability. These TRPV1-independent effects are mediated by alterations of the biophysical properties of the lipid membrane and subsequent modulation of the functional properties of ion channels and by direct binding of capsaicin to the channels. The present study, for the first time, systematically categorizes this diverse range of non-TRPV1 targets and discusses cellular and molecular mechanisms mediating TRPV1-independent effects of capsaicin in excitable, as well as nonexcitable cells.

STAT3 signaling in prostate cancer progression and therapy resistance: An oncogenic pathway with diverse functions

The categorization of cancers demonstrates that prostate cancer is the most common malignancy in men and it causes high death annually. Prostate cancer patients are diagnosed mainly via biomarkers such as PSA test and patients show poor prognosis. Prostate cancer cells rapidly diffuse into different parts of body and their metastasis is also a reason for death. Current therapies for prostate cancer patients include chemotherapy, surgery and radiotherapy as well as targeted therapy. The progression of prostate cancer cells is regulated by different factors that STAT3 signaling is among them. Growth factors and cytokines such as IL-6 can induce STAT3 signaling and it shows carcinogenic impact. Activation of STAT3 signaling occurs in prostate cancer and it promotes malignant behavior of tumor cells. Induction of STAT3 signaling increases glycolysis and proliferation of prostate cancer cells and prevents apoptosis. Furthermore, STAT3 signaling induces EMT mechanism in increasing cancer metastasis. Activation of STAT3 signaling stimulates drug resistance and the limitation of current works is lack of experiment related to role of STAT3 signaling in radio-resistance in prostate tumor. Calcitriol, capsazepine and β-elemonic are among the compounds capable of targeting STAT3 signaling and its inhibition in prostate cancer therapy. In addition to natural products, small molecules targeting STAT3 signaling have been developed in prostate cancer therapy.

Extraction, purification, bioactivity and pharmacological effects of capsaicin: a review

Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide), a well-known vanilloid, which is the main spicy component in chili peppers, showing several biological activities and the potential applications range from food flavorings to therapeutics. Traditional extraction of capsaicin by organic solvents was time-consuming, some new methods such as aqueous two-phase method and ionic liquid extraction method have been developed. During past few decades, an ample variety of biological effects of capsaicin have been evaluated. Capsaicin can be used in biofilms and antifouling coatings due to its antimicrobial activity, allowing it has a promising application in food packaging, food preservation, marine environment and dental therapy. Capsaicin also play a crucial role in metabolic disorders, including weight loss, pressure lowing and insulin reduction effects. In addition, capsaicin was identified effective on preventing human cancers, such as lung cancer, stomach cancer, colon cancer and breast cancer by inducing apoptosis and inhibiting cell proliferation of tumor cells. Previous research also suggest the positive effects of capsaicin on pain relief and cognitive impairment. Capsaicin, the agonist of transient receptor potential vanilloid type 1 (TRPV1), could selectively activate TRPV1, inducing Ca²⁺ influx and related signaling pathways. Recently, gut microbiota was also involved in some diseases therapeutics, but its influence on the effects of capsaicin still need to be deeply studied. In this review, different extraction and purification methods of capsaicin, its biological activities and pharmacological effects were systematically summarized, as well as the possible mechanisms were also deeply discussed. This article will give an updated and better understanding of capsaicin-related biological effects and provide theoretical basis for its further research and applications in human health and manufacture development.

TRPV1 Antagonist DWP05195 Induces ER Stress-Dependent Apoptosis through the ROS-p38-CHOP Pathway in Human Ovarian Cancer Cells

In addition to their analgesic activity, transient receptor potential vanilloid 1 (TRPV1) agonists and antagonists demonstrate profound anti-cancer activities in various human cancers. In the present study, we investigated the anti-cancer activity of a novel TRPV1 antagonist, DWP05195, and evaluated its molecular mechanism in human ovarian cancer cells. DWP05195 demonstrated potent growth inhibitory effects in all five ovarian cancer cell lines examined. DWP05195 induced apoptosis through the activation of caspase-3, -8, and -9. DWP05195 induced C/EBP homologous protein (CHOP) expression and endoplasmic reticulum (ER) stress. Sodium phenylbutyrate (4-PBA), an ER-stress inhibitor, and CHOP knockdown significantly suppressed DWP5195-induced cell death. DWP05195-enhanced CHOP expression stimulated intrinsic and extrinsic apoptotic pathways through the regulation of Bcl2-like11 (BIM), death receptor 4 (DR4), and DR5. DWP05195-induced cell death was associated with increased reactive oxygen species (ROS) levels and p38 pathway activation. Pre-treatment with the antioxidant N-acetyl-L-cysteine (NAC) significantly suppressed DWP05195-induced CHOP expression and p38 activation. Inhibition of NADPH oxidase (NOX) through p47phox knockdown abolished DWP05195-induced CHOP expression and cell death. Taken together, the findings indicate that DWP05195 induces ER stress-induced apoptosis via the ROS-p38-CHOP pathway in human ovarian cancer cells.

Pleiotropic Pharmacological Actions of Capsazepine, a Synthetic Analogue of Capsaicin, against Various Cancers and Inflammatory Diseases

Capsazepine is a synthetic analogue of capsaicin that can function as an antagonist of TRPV1. Capsazepine can exhibit diverse effects on cancer (prostate cancer, breast cancer, colorectal cancer, oral cancer, and osteosarcoma) growth and survival, and can be therapeutically used against other major disorders such as colitis, pancreatitis, malaria, and epilepsy. Capsazepine has been reported to exhibit pleiotropic anti-cancer effects against numerous tumor cell lines. Capsazepine can modulate Janus activated kinase (JAK)/signal transducer and activator of the transcription (STAT) pathway, intracellular Ca²⁺ concentration, and reactive oxygen species (ROS)-JNK-CCAAT/enhancer-binding protein homologous protein (CHOP) pathways. It can inhibit cell proliferation, metastasis, and induce apoptosis. Moreover, capsazepine can exert anti-inflammatory effects through the downregulation of lipopolysaccharide (LPS)-induced nuclear transcription factor-kappa B (NF-κB), as well as the blockage of activation of both transient receptor potential cation channel subfamily V member 1 (TRPV1) and transient receptor potential cation channel, subfamily A, and member 1 (TRPA1). This review briefly summarizes the diverse pharmacological actions of capsazepine against various cancers and inflammatory conditions.

Anticancer Activity of Natural and Synthetic Capsaicin Analogs

The nutritional compound capsaicin is the major spicy ingredient of chili peppers. Although traditionally associated with analgesic activity, recent studies have shown that capsaicin has profound antineoplastic effects in several types of human cancers. However, the applications of capsaicin as a clinically viable drug are limited by its unpleasant side effects, such as gastric irritation, stomach cramps, and burning sensation. This has led to extensive research focused on the identification and rational design of second-generation capsaicin analogs, which possess greater bioactivity than capsaicin. A majority of these natural capsaicinoids and synthetic capsaicin analogs have been studied for their pain-relieving activity. Only a few of these capsaicin analogs have been investigated for their anticancer activity in cell culture and animal models. The present review summarizes the current knowledge of the growth-inhibitory activity of natural capsaicinoids and synthetic capsaicin analogs. Future studies that examine the anticancer activity of a greater number of capsaicin analogs represent novel strategies in the treatment of human cancers.

Capsazepine inhibits JAK/STAT3 signaling, tumor growth, and cell survival in prostate cancer

Persistent STAT3 activation is seen in many tumor cells and promotes malignant transformation. Here, we investigated whether capsazepine (Capz), a synthetic analogue of capsaicin, exerts anticancer effects by inhibiting STAT3 activation in prostate cancer cells. Capz inhibited both constitutive and induced STAT3 activation in human prostate carcinoma cells. Capz also inhibited activation of the upstream kinases JAK1/2 and c-Src. The phosphatase inhibitor pervanadate reversed Capz-induced STAT3 inhibition, indicating that the effect of Capz depends on a protein tyrosine phosphatase. Capz treatment increased PTPε protein and mRNA levels. Moreover, siRNA-mediated knockdown of PTPε reversed the Capz-induced induction of PTPε and inhibition of STAT3 activation, indicating that PTPε is crucial for Capz-dependent STAT3 dephosphorylation. Capz also decreased levels of the protein products of various oncogenes, which in turn inhibited proliferation and invasion and induced apoptosis. Finally, intraperitoneal Capz administration decreased tumor growth in a xenograft mouse prostate cancer model and reduced p-STAT3 and Ki-67 expression. These data suggest that Capz is a novel pharmacological inhibitor of STAT3 activation with several anticancer effects in prostate cancer cells.

Cross-talk between alpha1D-adrenoceptors and transient receptor potential vanilloid type 1 triggers prostate cancer cell proliferation

Background

There is evidence that calcium (Ca²⁺) increases the proliferation of human advanced prostate cancer (PCa) cells but the ion channels involved are not fully understood. Here, we investigated the correlation between alpha_1D-adrenergic receptor (alpha_1D-AR) and the transient receptor potential vanilloid type 1 (TRPV1) expression levels in human PCa tissues and evaluated the ability of alpha_1D-AR to cross-talk with TRPV1 in PCa cell lines.

Methods

The expression of alpha_1D-AR and TRPV1 was examined in human PCa tissues by quantitative RT-PCR and in PCa cell lines (DU145, PC3 and LNCaP) by cytofluorimetry. Moreover, alpha_1D-AR and TRPV1 colocalization was investigated by confocal microscopy in PCa cell lines and by fluorescence microscopy in benign prostate hyperplasia (BPH) and PCa tissues. Cell proliferation was assessed by BrdU incorporation. Alpha_1D-AR/TRPV1 knockdown was obtained using siRNA transfection. Signalling pathways were evaluated by measurement of extracellular acidification rate, Ca²⁺ flux, IP₃ production, western blot and MTT assay.

Results

The levels of the alpha_1D-AR and TRPV1 mRNAs are increased in PCa compared to BPH specimens and a high correlation between alpha_1D-AR and TRPV1 expression levels was found. Moreover, alpha_1D-AR and TRPV1 are co-expressed in prostate cancer cell lines and specimens. Noradrenaline (NA) induced an alpha_1D-AR- and TRPV1-dependent protons release and Ca²⁺ flux in PC3 cell lines; NA by triggering the activation of phospholipase C (PLC), protein kinase C (PKC) and extracellular signal-regulated kinase 1/2 (ERK1/2) pathways stimulated PC3 cell proliferation, that was completely inhibited by clopenphendioxan (WS433) and capsazepine (CPZ) combination or by alpha_1D-AR/TRPV1 double knockdown.

Conclusions

We demonstrate a cross-talk between alpha_1D-AR and TRPV1, that is involved in the control of PC3 cell proliferation. These data strongly support for a putative novel pharmacological approach in the treatment of PCa by targeting both alpha_1D-AR and TRPV1 channels.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-921) contains supplementary material, which is available to authorized users.

Mitochondria: a possible nexus for the regulation of energy homeostasis by the endocannabinoid system?

The endocannabinoid system (ECS) regulates numerous cellular and physiological processes through the activation of receptors targeted by endogenously produced ligands called endocannabinoids. Importantly, this signaling system is known to play an important role in modulating energy balance and glucose homeostasis. For example, current evidence indicates that the ECS becomes overactive during obesity whereby its central and peripheral stimulation drives metabolic processes that mimic the metabolic syndrome. Herein, we examine the role of the ECS in modulating the function of mitochondria, which play a pivotal role in maintaining cellular and systemic energy homeostasis, in large part due to their ability to tightly coordinate glucose and lipid utilization. Because of this, mitochondrial dysfunction is often associated with peripheral insulin resistance and glucose intolerance as well as the manifestation of excess lipid accumulation in the obese state. This review aims to highlight the different ways through which the ECS may impact upon mitochondrial abundance and/or oxidative capacity and, where possible, relate these findings to obesity-induced perturbations in metabolic function. Furthermore, we explore the potential implications of these findings in terms of the pathogenesis of metabolic disorders and how these may be used to strategically develop therapies targeting the ECS.

Methodological Triangulation Using Neural Networks for Business Research

Artificial neural network (ANN) modeling methods are becoming more widely used as both a research and application paradigm across a much wider variety of business, medical, engineering, and social science disciplines. The combination or triangulation of ANN methods with more traditional methods can facilitate the development of high-quality research models and also improve output performance for real world applications. Prior methodological triangulation that utilizes ANNs is reviewed and a new triangulation of ANNs with structural equation modeling and cluster analysis for predicting an individual's computer self-efficacy (CSE) is shown to empirically analyze the effect of methodological triangulation, at least for this specific information systems research case. A new construct, engagement, is identified as a necessary component of CSE models and the subsequent triangulated ANN models are able to achieve an 84% CSE group prediction accuracy.

Effect of thapsigargin on Ca²+ fluxes and viability in human prostate cancer cells

Effect of the carcinogen thapsigargin on human prostate cancer cells is unclear. This study examined if thapsigargin altered basal [Ca²⁺](i) levels in suspended PC3 human prostate cancer cells by using fura-2 as a Ca²⁺-sensitive fluorescent probe. Thapsigargin at concentrations between 10 nM and 10 µM increased [Ca²⁺](i) in a concentration-dependent fashion. The Ca²⁺ signal was reduced partly by removing extracellular Ca²⁺ indicating that Ca²⁺ entry and release both contributed to the [Ca²⁺](i) rise. This Ca²⁺ influx was inhibited by suppression of phospholipase A2, but not by inhibition of store-operated Ca²⁺ channels or by modulation of protein kinase C activity. In Ca²⁺-free medium, pretreatment with the endoplasmic reticulum Ca²⁺ pump inhibitor 2,5-di-(t-butyl)-1,4-hydroquinone (BHQ) nearly abolished thapsigargin-induced Ca²⁺ release. Conversely, pretreatment with thapsigargin greatly reduced BHQ-induced [Ca²⁺](i) rise, suggesting that thapsigargin released Ca²⁺ from the endoplasmic reticulum. Inhibition of phospholipase C did not change thapsigargin-induced [Ca²⁺](i) rise. At concentrations of 1-10 µM, thapsigargin induced cell death that was partly reversed by chelation of Ca²⁺ with BAPTA/AM. Annexin V/propidium iodide staining data suggest that apoptosis was partly responsible for thapsigargin-induced cell death. Together, in PC3 human prostate cancer cells, thapsigargin induced [Ca²⁺](i) rises by causing phospholipase C-independent Ca²⁺ release from the endoplasmic reticulum and Ca²⁺ influx via phospholipase A2-sensitive Ca²⁺ channels. Thapsigargin also induced cell death via Ca²⁺-dependent pathways and Ca²⁺-independent apoptotic pathways.

Effect of diallyl disulfide on Ca2+ movement and viability in PC3 human prostate cancer cells

The effect of diallyl disulfide (DADS) on cytosolic Ca(2+) concentrations ([Ca(2+)](i)) and viability in PC3 human prostate cancer cells is unclear. This study explored whether DADS changed [Ca(2+)](i) in PC3 cells by using fura-2. DADS at 50-1000 μM increased [Ca(2+)](i) in a concentration-dependent manner. The signal was reduced by removing Ca(2+). DADS-induced Ca(2+) influx was not inhibited by nifedipine, econazole, SK&F96365, and protein kinase C modulators; but was inhibited by aristolochic acid. In Ca(2+)-free medium, pretreatment with the endoplasmic reticulum Ca(2+) pump inhibitors thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ) nearly abolished DADS-induced [Ca(2+)](i) rise. Incubation with DADS inhibited thapsigargin or BHQ-induced [Ca(2+)](i) rise. Inhibition of phospholipase C with U73122 did not alter DADS-induced [Ca(2+)](i) rise. At 500-1000 μM, DADS killed cells in a concentration-dependent manner. The cytotoxic effect of DADS was partly reversed by prechelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Propidium iodide staining suggests that DADS (500 μM) induced apoptosis in a Ca(2+)-independent manner. Annexin V/PI staining further shows that 10 μM and 500 μM DADS both evoked apoptosis. DADS also increased reactive oxygen species (ROS) production. Collectively, in PC3 cells, DADS induced [Ca(2+)](i) rise probably by causing phospholipase C-independent Ca(2+) release from the endoplasmic reticulum and Ca(2+) influx via phospholipase A(2)-sensitive channels. DADS induced Ca(2+)-dependent cell death, ROS production, and Ca(2+)-independent apoptosis.

Vanilloid receptor agonists and antagonists are mitochondrial inhibitors: how vanilloids cause non-vanilloid receptor mediated cell death

Time-lapse photomicroscopy of human H460 lung cancer cells demonstrated of the transient receptor potential V1 (TRPV1) channel agonists, (E)-capsaicin and resiniferatoxin, and the TRPV1 antagonists, capsazepine, and SB366791, were able to bring about morphological changes characteristic of apoptosis and/or necrosis. Immunoblot analysis identified immunoreactivity for the transient receptor potential V1 (TRPV1) channel in rat brain samples, but not in rat heart mitochondria or in H460 cells. In isolated rat heart mitochondria, all four ligands caused concentration-dependent decreases in oxygen consumption and mitochondrial membrane potential. (E)-Capsaicin and capsazepine evoked concentration-dependent increases and decreases, respectively, in mitochondrial hydrogen peroxide production, whilst resiniferatoxin and SB366791 were without significant effect. These data support the hypothesis that (E)-capsaicin, resiniferatoxin, capsazepine, and SB366791 are all mitochondrial inhibitors, able to activate apoptosis and/or necrosis via non-receptor mediated mechanisms, and also support the use of TRPV1 ligands as anti-cancer agents.