Capsaicin induced apoptosis of B16-F10 melanoma cells through down-regulation of Bcl-2

Capsaicin: Emerging Pharmacological and Therapeutic Insights

Capsaicin, the most prominent pungent compound of chilli peppers, has been used in traditional medicine systems for centuries; it already has a number of established clinical and industrial applications. Capsaicin is known to act through the TRPV1 receptor, which exists in various tissues; capsaicin is hepatically metabolised, having a half-life correlated with the method of application. Research on various applications of capsaicin in different formulations is still ongoing. Thus, local capsaicin applications have a pronounced anti-inflammatory effect, while systemic applications have a multitude of different effects because their increased lipophilic character ensures their augmented bioavailability. Furthermore, various teams have documented capsaicin's anti-cancer effects, proven both in vivo and in vitro designs. A notable constraint in the therapeutic effects of capsaicin is its increased toxicity, especially in sensitive tissues. Regarding the traditional applications of capsaicin, apart from all the effects recorded as medicinal effects, the application of capsaicin in acupuncture points has been demonstrated to be effective and the combination of acupuncture and capsaicin warrants further research. Finally, capsaicin has demonstrated antimicrobial effects, which can supplement its anti-inflammatory and anti-carcinogenic actions.

Spice-Derived Phenolic Compounds: Potential for Skin Cancer Prevention and Therapy

Skin cancer is a condition characterized by the abnormal growth of skin cells, primarily caused by exposure to ultraviolet (UV) radiation from the sun or artificial sources like tanning beds. Different types of skin cancer include melanoma, basal cell carcinoma, and squamous cell carcinoma. Despite the advancements in targeted therapies, there is still a need for a safer, highly efficient approach to preventing and treating cutaneous malignancies. Spices have a rich history dating back thousands of years and are renowned for their ability to enhance the flavor, taste, and color of food. Derived from various plant parts like seeds, fruits, bark, roots, or flowers, spices are important culinary ingredients. However, their value extends beyond the culinary realm. Some spices contain bioactive compounds, including phenolic compounds, which are known for their significant biological effects. These compounds have attracted attention in scientific research due to their potential health benefits, including their possible role in disease prevention and treatment, such as cancer. This review focuses on examining the potential of spice-derived phenolic compounds as preventive or therapeutic agents for managing skin cancers. By compiling and analyzing the available knowledge, this review aims to provide insights that can guide future research in identifying new anticancer phytochemicals and uncovering additional mechanisms for combating skin cancer.

Biomedical and Antioxidant Potentialities in Chilli: Perspectives and Way Forward

Worldwide, since ages and nowadays, traditional medicine is well known, owing to its biodiversity, which immensely contributed to the advancement and development of complementary and alternative medicines. There is a wide range of spices, herbs, and trees known for their medicinal uses. Chilli peppers, a vegetable cum spice crop, are bestowed with natural bioactive compounds, flavonoids, capsaicinoids, phytochemicals, phytonutrients, and pharmacologically active compounds with potential health benefits. Such compounds manifest their functionality over solo-treatment by operating in synergy and consortium. Co-action of these compounds and nutrients make them potentially effective against coagulation, obesity, diabetes, inflammation, dreadful diseases, such as cancer, and microbial diseases, alongside having good anti-oxidants with scavenging ability to free radicals and oxygen. In recent times, capsaicinoids especially capsaicin can ameliorate important viral diseases, such as SARS-CoV-2. In addition, capsaicin provides an ability to chilli peppers to ramify as topical agents in pain-relief and also benefitting man as a potential effective anesthetic agent. Such phytochemicals involved not only make them useful and a much economical substitute to wonder/artificial drugs but can be exploited as obscene drugs for the production of novel stuffs. The responsibility of the TRPV1 receptor in association with capsaicin in mitigating chronic diseases has also been justified in this study. Nonetheless, medicinal studies pertaining to consumption of chilli peppers are limited and demand confirmation of the findings from animal studies. In this artifact, an effort has been made to address in an accessible format the nutritional and biomedical perspectives of chilli pepper, which could precisely upgrade and enrich our pharmaceutical industries towards human well-being.

1,2,3-Triazole Tethered Hybrid Capsaicinoids as Antiproliferative Agents Active against Lung Cancer Cells (A549)

A series of novel 1,2,3-triazole derivatives of capsaicin and its structural isomer (new natural product hybrid capsaicinoid) were synthesized by exploiting one-/two-point modification of capsaicin without altering the amide linkage (neck). The newly synthesized compounds were screened for their antiproliferative activity against an NCI panel of 60 cancer cell lines at a single dose of 10 μM. Most of the compounds have demonstrated reduced growth between 55 and 95%, whereas capsaicin (10) has shown reduced growth between 0 and 24%. Compounds showing more than 50% growth inhibition were further evaluated for the IC50 value. Among the cell lines tested, lung cancer cell lines (A549, NCI-H460) were found to be more susceptible toward most of the synthesized compounds. Compounds 14g and 14j demonstrated good antiproliferative activity in NCI-H460 with IC50 values of 6.65 and 5.55 μM, respectively, while compounds 18b, 18c, 18f, and 18m demonstrated potential antiproliferative activity in A549 cell lines with IC50 values ranging between 2.9 and 10.5 μM. Among the compounds, compound 18f was found to demonstrate the best activity with an IC50 value of 2.91 μM against A549. Furthermore, 18f induces cell cycle arrest at the S-phase and disrupts the mitochondrial membrane potential, reducing cell migration potential by inducing cellular apoptosis and higher ROS generation along with a decrease in mitochondrial membrane potential in addition to surface and nuclear morphological alterations such as a reduction in the number and shrinkage of cells coupled with nuclear blabbing indicating the sign of apoptosis of A549 non-small cell lung cancer cell lines. Compound 18f has emerged as a lead molecule and may serve as a template for further discovery of capsaicinoid scaffolds.

The cell membrane as the barrier in the defense against nanoxenobiotics: Zinc oxide nanoparticles interactions with native and model membrane of melanoma cells

Currently, we are dealing with ever-increasing pollution of the environment with metal and metal oxide nanoparticles. One type of these, zinc oxide nanoparticles (ZnO-NPs), are increasingly used in areas such as cosmetology, electrical engineering, medicine, and even in the food and textile industries. As a consequence, ZnO-NPs may enter the human body in many ways. Their influence on the body is still not clear. Here, we define the mechanism of the initial toxicity of ZnO-NPs to cells based on interaction with the lipid part of the native and model cell membrane. The selected cell lines react differently to contact with nanoparticles. We found a disruption of the native membranes of B16-F0 cells and to a lesser extent of COLO 679. In turn, the membrane of COLO 679 cells was more peroxidated, and cell viability was much lower. A model of the lipid part of the membrane was created for B16-F0 cells and compared with previously published studies on immune cells. On the basis of physicochemical parameters obtained for individual lipids and a mix representing the native membrane of the tested cells, we concluded that exposure to nanoparticles resulted in a change within the model membranes (specifically with the polar parts of lipids). The greatest interaction has been noticed between ZnO-NPs and zwitterionic phospholipids (PC and PE), cholesterol, and negatively charged phosphatidylglycerol. Assessing the interactions between the membrane and nanoparticles will help to better understand the first steps of its toxicity mechanism.

In Vitro Effects of Selective COX and LOX Inhibitors and Their Combinations with Antineoplastic Drugs in the Mouse Melanoma Cell Line B16F10

The constitutive expression or overactivation of cyclooxygenase (COX) and lipoxygenase (LOX) enzymes results in aberrant metabolism of arachidonic acid and poor prognosis in melanoma. Our aim is to compare the in vitro effects of selective COX-1 (acetylsalicylic acid), COX-2 (meloxicam), 5-LOX (MK-886 and AA-861), 12-LOX (baicalein) and 15-LOX (PD-146176) inhibition in terms of proliferation (SRB assay), mitochondrial viability (MTT assay), caspase 3-7 activity (chemiluminescent assay), 2D antimigratory (scratch assay) and synthesis of eicosanoids (EIA) in the B16F10 cell line (single treatments). We also explore their combinatorial pharmacological space with dacarbazine and temozolomide (median effect method). Overall, our results with single treatments show a superior cytotoxic efficacy of selective LOX inhibitors over selective COX inhibitors against B16F10 cells. PD-146176 caused the strongest antiproliferation effect which was accompanied by cell cycle arrest in G₁ phase and an >50-fold increase in caspases 3/7 activity. When the selected inhibitors are combined with the antineoplastic drugs, only meloxicam provides clear synergy, with LOX inhibitors mostly antagonizing. These apparent contradictions between single and combination treatments, together with some paradoxical effects observed in the biosynthesis of eicosanoids after FLAP inhibition in short term incubations, warrant further mechanistical in vitro and in vivo scrutiny.

Ablation of sensory nerves favours melanoma progression

The tumour mass is composed not only of heterogeneous neoplastic cells, but also a variety of other components that may affect cancer cells behaviour. The lack of detailed knowledge about all the constituents of the tumour microenvironment restricts the design of effective treatments. Nerves have been reported to contribute to the growth and maintenance of numerous tissues. The effects of sensory innervations on tumour growth remain unclear. Here, by using state-of-the-art techniques, including Cre/loxP technologies, confocal microscopy, in vivo-tracing and chemical denervation, we revealed the presence of sensory nerves infiltrating within the melanoma microenvironment, and affecting cancer progression. Strikingly, melanoma growth in vivo was accelerated following genetic ablation or chemical denervation of sensory nerves. In humans, a retrospective analysis of melanoma patients revealed that increased expression of genes related to sensory nerves in tumours was associated with better clinical outcomes. These findings suggest that sensory innervations counteract melanoma progression. The emerging knowledge from this research provides a novel target in the tumour microenvironment for therapeutic benefit in cancer patients.

Factors affecting the capsaicinoid profile of hot peppers and biological activity of their non-pungent analogs (Capsinoids) present in sweet peppers

Capsaicinoids are acid amides of C₉-C₁₁ branched-chain fatty acids and vanillylamine and constitute important chemical compounds of Capsicum annuum together with their non-pungent analogs (capsinoids) which have an impressive list of health benefit properties (i.e., analgesia, anti-obesity, thermogenic, cardiovascular, gastrointestinal, antioxidant, anti-bacterial, anti-virulence, anti-inflamatory, anti-diabetic, inhibits angiogenesis, and improves glucose metabolism) . In this review, the state of art on how capsaicinoids are affected by different pre- and postharvest factors is discussed together with their biological activity. For instance, high light intensity and heat treatments may reduce capsaicinoid content in fruits probably due to the loss of activity of capsaicin synthase (CS) and phenylalanine ammonia lyase (PAL). The pungency in peppers varies also with environment, genotype or cultivar, node position, fruiting and maturity stages, nitrogen and potassium contents. As the fruit mature, capsaicinoid levels increase. Fruits from the second node tend to have higher accumulation of pungency than those of other positions and the pungency decreases linearly as the node position increase. Sodium hydroxide treatment reduces the pungency of pepper fruit as it hydrolyzes and modifies one of the features (vanillyl group, the acid-amide linkage and alkyl side chain) of capsaicin molecule. Salt and water stress increase PAL and capsaicin synthase activity and increase the capsaicinoid accumulation in fruit, by negatively regulating peroxidase activity at appropriate levels. Future research must be directed in better understanding the changes of capsinoids during pre and post-harvest management, the causal drivers of the loss of activity of the aminotransferase gene (pAMT) and if possible, studies with genetically modified sweet peppers with functional pAMT. Available data provided in this review can be used in different agricultural programs related to developing new cultivars with specific pungency levels. The contents of capsaicinoids and capsinoids in both fresh fruits and marketed products are also of remarkable importance considering the preferences of certain niches in market where higher added-value products might be commercialized.

Unraveling the molecular mechanisms and the potential chemopreventive/therapeutic properties of natural compounds in melanoma

Melanoma is the most fatal form of skin cancer. Current therapeutic approaches include surgical resection, chemotherapy, targeted therapy and immunotherapy. However, these treatment strategies are associated with development of drug resistance and severe side effects. In recent years, natural compounds have also been extensively studied for their anti-melanoma effects, including tumor growth inhibition, apoptosis induction, angiogenesis and metastasis suppression and cancer stem cell elimination. Moreover, a considerable number of studies reported the synergistic activity of phytochemicals and standard anti-melanoma agents, as well as the enhanced effectiveness of their synthetic derivatives and novel formulations. However, clinical data confirming these promising effects in patients are still scanty. This review emphasizes the anti-tumor mechanisms and potential application of the most studied natural products for melanoma prevention and treatment.

Capsaicin-like analogue induced selective apoptosis in A2058 melanoma cells: Design, synthesis and molecular modeling

The use of molecules inspired by natural scaffolds has proven to be a very promising and efficient method of drug discovery. In this work, capsaicin, a natural product from Capsicum peppers with antitumor properties, was used as a prototype to obtain urea and thiourea analogues. Among the most promising compounds, the thiourea compound 6g exhibited significant cytotoxic activity against human melanoma A2058 cells that was twice as high as that of capsaicin. Compound 6g induced significant and dose-dependent G₀/G₁ cell cycle arrest in A2058 cells triggering cell death by apoptosis. Our results suggest that 6g modulates the RAF/MEK/ERK pathway, inducing important morphological changes, such as formation of apoptotic bodies and increased levels of cleaved caspase-3. Compared to capsaicin, 6g had no significant TRPV1/6 agonist effect or irritant effects on mice. Molecular modeling studies corroborate the biological findings and suggest that 6g, besides being a more reactive molecule towards its target, may also present a better pharmacokinetic profile than capsaicin. Inverse virtual screening strategy found MEK1 as a possible biological target for 6g. Consistent with these findings, our observations suggested that 6g could be developed as a potential anticancer agent.

Capsaicin induces apoptosis and autophagy in human melanoma cells

Melanoma is the most lethal type of skin cancer; rapid metastasis and resistance to conventional radio- and chemotherapy make melanoma the most aggressive type of skin cancer. In addition, there is a high recurrence rate within 1 year among patients with melanoma following traditional treatment by chemotherapy or immunotherapy, and these treatment options are only useful in advanced stages. As the efficiency of treatment options for melanoma is not ideal, the present study aimed to confirm that capsaicin has inhibitory effects on the human melanoma A375 and C8161 cell lines in vitro. Capsaicin, the active component of peppers, has been reported to possess substantial anticarcinogenic and antimutagenic activities. Additionally, capsaicin exhibits an inhibitory effect on tumor growth in numerous malignant cell lines. In the present study, flow cytometry, fluorescent puncta detection and western blotting were performed. The experimental results indicated that capsaicin activated apoptosis, and that apoptosis induction was associated with poly(ADP-ribose) polymerase (PARP) cleavage and activation of caspase-3. Additionally, the formation of autophagosomes and accumulation of microtubule-associated proteins 1A/1B light chain 3B-II and beclin 1 suggested that capsaicin induced autophagy in human melanoma cells. Furthermore, inhibiting capsaicin-induced autophagy promoted the activation of cleaved caspase-3 and PARP proteins, which are associated with apoptosis. In addition, inhibition of autophagy using 3-MA enhanced capsaicin-induced cell death, indicating that capsaicin-induced autophagy is a pro-survival process in cells. In conclusion, the results of the present study revealed that capsaicin induced cell apoptosis and autophagy in human melanoma cells and capsaicin may be considered as a novel candidate drug for melanoma treatment.

Capsaicin: Friend or Foe in Skin Cancer and Other Related Malignancies?

Capsaicin is the main pungent in chili peppers, one of the most commonly used spices in the world; its analgesic and anti-inflammatory properties have been proven in various cultures for centuries. It is a lipophilic substance belonging to the class of vanilloids and an agonist of the transient receptor potential vanilloid 1 receptor. Taking into consideration the complex neuro-immune impact of capsaicin and the potential link between inflammation and carcinogenesis, the effect of capsaicin on muco-cutaneous cancer has aroused a growing interest. The aim of this review is to look over the most recent data regarding the connection between capsaicin and muco-cutaneous cancers, with emphasis on melanoma and muco-cutaneous squamous cell carcinoma.

Ascorbyl palmitate-incorporated paclitaxel-loaded composite nanoparticles for synergistic anti-tumoral therapy

A co-loaded drug delivery system based on ascorbyl palmitate that can transport various functional drugs to their targets within a tumor represents an attractive strategy for increasing the efficiency of anticancer treatment. In this study, we developed a dual drug delivery system to encapsulate ascorbyl palmitate (AP) and paclitaxel (PTX) for synergistic cancer therapy. AP, which is a vitamin C derivative, and PTX were incorporated into solid lipid nanoparticles (AP/PTX-SLNs), which were used to treat murine B16F10 melanoma that had metastasized to the lungs of mice. These nanoparticles were spherical with an average size of 223 nm as measured by transmission electron microscope and dynamic light scattering. In vitro cytotoxicity assays indicated that the AP/PTX-SLNs with an AP/PTX mass ratio of 2/1 provided the optimal synergistic anticancer efficacy. In vivo, AP/PTX-SLNs were revealed to be much more effective in suppressing tumor growth in B16F10-bearing mice and in eliminating cancer cells in the lungs than single drug (AP or PTX)-loaded SLNs via a synergistic effect through reducing the Bcl-2/Bax ratio. Furthermore, no marked side effects were observed during the treatment with the AP/PTX-SLNs, indicating that the co-delivery system with ascorbyl palmitate holds promising clinical potential in cancer therapy.

Assessing the anticancer effects associated with food products and/or nutraceuticals using in vitro and in vivo preclinical development-related pharmacological tests

This review is part of a special issue entitled "Role of dietary pattern, foods, nutrients and nutraceuticals in supporting cancer prevention and treatment" and describes a pharmacological strategy to determine the potential contribution of food-related components as anticancer agents against established cancer. Therefore, this review does not relate to chemoprevention, which is analysed in several other reviews in the current special issue, but rather focuses on the following: i) the biological events that currently represent barriers against the treatment of certain types of cancers, primarily metastatic cancers; ii) the in vitro and in vivo pharmacological pre-clinical tests that can be used to analyse the potential anticancer effects of food-related components; and iii) several examples of food-related components with anticancer effects. This review does not represent a catalogue-based listing of food-related components with more or less anticancer activity. By contrast, this review proposes an original pharmacological strategy that researchers can use to analyse the potential anticancer activity of any food-related component-e.g., by considering the crucial characteristics of cancer biological aggressiveness. This review also highlights that cancer patients undergoing chemotherapy should restrict the use of "food complements" without supervision by a medical nutritionist. By contrast, an equilibrated diet that includes the food-related components listed herein would be beneficial for cancer patients who are not undergoing chemotherapy.

Health-promoting properties of compounds derived from Capsicum sp. A review

This article presents multidirectional effects of capsaicin and its natural derivatives as well as natural and synthetic analogs in term of their therapeutic properties. Active agents present in various Capsicum genus plants exert analgesic, anti-inflammatory, antibacterial, antioxidant and gastroprotective effects. Furthermore, capsaicin positively influences the metabolism of lipids. Numerous research show that capsaicinoids inhibit proliferation and migration process of cancer cells, what makes them molecules of high interest in oncology. Among broad range of positive activities, we have focused only on those properties that have already found application in medicine or seemed to be the most probably used in the near future. Even if in low or single doses this compound has been reported successful in numerous therapies, the negative consequences of high doses or prolonged administration is also discussed in the review.

An updated review on molecular mechanisms underlying the anticancer effects of capsaicin

The quest for developing anticancer principles from natural sources has a long historical track record and remarkable success stories. The pungent principle of hot chili pepper, capsaicin, has been a subject of research for anticancer drug discovery for more than three decades. However, the majority of research has revealed that capsaicin interferes with various hallmarks of cancer, such as increased cell proliferation, evasion from apoptosis, inflammation, tumor angiogenesis and metastasis, and tumor immune escape. Moreover, the compound has been reported to inhibit carcinogen activation and chemically induced experimental tumor growth. Capsaicin has also been reported to inhibit the activation of various kinases and transcription that are involved in tumor promotion and progression. The compound activated mitochondria-dependent and death receptor-mediated tumor cell apoptosis. Considering the growing interest in capsaicin, this review provides an update on the molecular targets of capsaicin in modulating oncogenic signaling.

In vivo and in vitro evaluation for nutraceutical purposes of capsaicin, capsanthin, lutein and four pepper varieties

The purpose of this study is to determine the nutraceutic potential of different Capsicum sp, capsaicin, capsanthin and lutein and provide data in order to clarify the conflicting results obtained for capsaicin by different authors. To achieve these objectives, in vivo (geno/antigenotoxicity and lifespan assays in the animal model Drosophila) and in vitro (cytotoxicity and DNA-fragmentation assays in HL60 promyelocytic cell line) assays were carried out. Results showed that i) none of the tested substances were genotoxic except green hot pepper and capsaicin at the highest tested concentration (5 mg/mL and 11.5 μM respectively), ii) all tested substances except green hot pepper are antimutagenic against H₂O₂-induced damage, iii) only red sweet pepper significantly extend the lifespan and healthspan of D. melanogaster at 1.25 and 2.5 mg/mL, iv) all pepper varieties induce dose-depended cytotoxic effect in HL60 cells with different IC₅₀, and v) all pepper varieties and capsaicin exerted proapoptotic effect on HL60 cells.

IN CONCLUSION

(i) sweet peppers could be suggested as nutraceutical food, (ii) hot peppers should be moderately consumed, and (iii) supplementary studies are necessary to clarify the synergic effect of the carotenoids and capsaicinoids in the hot pepper food matrix.

Capsaicin: From Plants to a Cancer-Suppressing Agent

Capsaicinoids are plant secondary metabolites, capsaicin being the principal responsible for the pungency of chili peppers. It is biosynthesized through two pathways involved in phenylpropanoid and fatty acid metabolism. Plant capsaicin concentration is mainly affected by genetic, environmental and crop management factors. However, its synthesis can be enhanced by the use of elicitors. Capsaicin is employed as food additive and in pharmaceutical applications. Additionally, it has been found that capsaicin can act as a cancer preventive agent and shows wide applications against various types of cancer. This review is an approach in contextualizing the use of controlled stress on the plant to increase the content of capsaicin, highlighting its synthesis and its potential use as anticancer agent.

Multidimensional Separation of Natural Products Using Liquid Chromatography Coupled to Hadamard Transform Ion Mobility Mass Spectrometry

A high performance liquid chromatograph (HPLC)was interfaced to an atmospheric drift tube ion mobility time of flight mass spectrometry. The power of multidimensional separation was demonstrated using chili pepper extracts. The ambient pressure drift tube ion mobility provided high resolving powers up to 166 for the HPLC eluent. With implementation of Hadamard transform (HT), the duty cycle for the ion mobility drift tube was increased from less than 1% to 50%, and the ion transmission efficiency was improved by over 200 times compared with pulsed mode, improving signal to noise ratio 10 times. HT ion mobility and TOF mass spectrometry provide an additional dimension of separation for complex samples without increasing the analysis time compared with conventional HPLC. Graphical Abstract ᅟ.

Role of Autophagy in Capsaicin-Induced Apoptosis in U251 Glioma Cells

In recent years, the role of capsaicin in cancer prevention and treatment has gained people's attention. However, the mechanism of anti-glioma cells by capsaicin has not been elucidated. Here, we discuss the mechanism of capsaicin in U251 cells. Cell viability was detected by MTT and extracellular LDH measurements, while immunofluorescence was performed to measure changes of LC3 in U251 cells. The expressions of LC3II, Puma-α, Beclin1, P62, Procaspase-3, and P53 were observed by immunoblotting. The cell viability decreased and the punctate patterns of LC3 in U251 cells were observed after Capsaicin treatment. Meanwhile, the expressions of Beclin1, P62, and Puma-α increased. After using 3-MA, the expressions of Beclin1 and Procaspase-3 were reduced while those of P53 and Puma-α increased. The expression of LC3II was increased after Pifithrin-α treatment. Therefore, we believed that capsaicin could induce apoptosis in U251 cells, and the inhibition of autophagy could contribute to apoptosis.

A Comprehensive Review of the Carcinogenic and Anticarcinogenic Potential of Capsaicin

Human exposure to capsaicin, the most abundant pungent chili pepper component, is ubiquitous. Evaluation of capsaicin’s carcinogenic potential has produced variable results in in vitro and in vivo genotoxicity and carcinogenicity assays. The capsaicin tested in older studies was often from pepper plant extracts and included other capsaicinoids and diverse impurities. Recent studies utilizing high-purity capsaicin and standardized protocols provide evidence that the genotoxic and carcinogenic potential of capsaicin is quite low and that the purity of capsaicin is important. Several small epidemiological studies suggest a link between capsaicin consumption and stomach or gall bladder cancer, but contamination of capsaicin-containing foods with known carcinogens renders their interpretation problematic. The postulated ability of capsaicin metabolites to damage DNA and promote carcinogenesis remains unsupported. Anticancer activities of capsaicin have been widely reported, as it inhibits the activity of carcinogens and induces apoptosis in numerous cancer cell lines in vitro and explanted into rodents. Diverse mechanisms have been postulated for capsaicin’s anticancer properties. One hypothesis is that inhibition of cytochrome P450 enzymes—particularly CYP2E1—retards carcinogen activation but is contradicted by the low potency of capsaicin for CYP inhibition. The potential for dietary capsaicin to act as a chemopreventative is now widely postulated.

Cancer and diet: How are they related?

Extensive research in the past decade has revealed cancer to be a multigenic disease caused by perturbation of multiple cell signalling pathways and dysregulation of numerous gene products, all of which have been linked to inflammation. It is also becoming evident that various lifestyle factors, such as tobacco and alcohol use, diet, environmental pollution, radiation and infections, can cause chronic inflammation and lead to tumourigenesis. Chronic diseases caused by ongoing inflammation therefore require chronic, not acute, treatment. Nutraceuticals, compounds derived from fruits, vegetables, spices and cereals, can be used chronically. This study discusses the molecular targets of some nutraceuticals that happen to be markers of chronic inflammation and how they can prevent or treat cancer. These naturally-occurring agents in the diet have great potential as anti-cancer drugs, thus proving Hippocrates, who proclaimed 25 centuries ago, 'Let food be thy medicine and medicine be thy food'.

PPARgamma: The Portrait of a Target Ally to Cancer Chemopreventive Agents

Peroxisome proliferator-activated receptor-gamma (PPARγ), one of three ligand-activated transcription factors named PPAR, has been identified as a molecular target for cancer chemopreventive agents. PPARγ was initially understood as a regulator of adipocyte differentiation and glucose homeostasis while later on, it became evident that it is also involved in cell differentiation, apoptosis, and angiogenesis, biological processes which are deregulated in cancer. It is now established that PPARγ ligands can induce cell differentiation and yield early antineoplastic effects in several tumor types. Moreover, several bioactive natural products with cancer protecting potential are shown to operate through activation of PPARγ. Overall, PPARγ appears to be a prevalent target ally to cancer chemopreventive agents and therefore pursuing research in this area is of great relevance.

Suppression of EGF-induced tumor cell migration and matrix metalloproteinase-9 expression by capsaicin via the inhibition of EGFR-mediated FAK/Akt, PKC/Raf/ERK, p38 MAPK, and AP-1 signaling

SCOPE

Capsaicin is a cancer-suppressing agent. The aim of our study was to determine the effect of capsaicin on tumor invasion and migration; the possible mechanisms involved in this inhibition were investigated in human fibrosarcoma cells.

METHODS AND RESULTS

We employed invasion, migration and gelatin zymography assays to characterize the effect of capsaicin on HT-1080 cells. Transient transfection assays and immunoblot analysis were performed to study its molecular mechanisms of action. Capsaicin inhibited the epidermal growth factor (EGF)-induced activation of matrix metalloproteinase (MMP)-9 and MMP-2, and further inhibited cell invasion and migration. Capsaicin decreased the EGF-induced expression of MMP-9, MMP-2, and MT1-MMP, but did not alter TIMP-1 and TIMP-2 levels. Capsaicin suppressed EGF-induced c-Jun and c-Fos nuclear translocation, and also abrogated the EGF-induced phosphorylation of EGF receptor (EGFR), focal adhesion kinase (FAK), protein kinase C (PKC), phosphatidylinositol 3-Kinase (PI3K)/Akt, extracellular regulated kinase (ERK)1/2, and JNK1/2, an upstream modulator of AP-1. Furthermore, the EGFR inhibitor inhibited EGF-induced MMP-9 expression, as well as AP-1 activity and cell migration.

CONCLUSION

Capsaicin inhibited the EGF-induced invasion and migration of human fibrosarcoma cells via EGFR-dependent FAK/Akt, PKC/Raf/ERK, p38 mitogen-activated protein kinase (MAPK), and AP-1 signaling, leading to the down-regulation of MMP-9 expression. These results indicate the role of capsaicin as a potent anti-metastatic agent, which can markedly inhibit the metastatic and invasive capacity of fibrosarcoma cells.

Anticancer properties of 10-hydroxycamptothecin in a murine melanoma pulmonary metastasis model in vitro and in vivo

Lung cancer, including lung metastatic cancer, remains one of the most difficult types of cancer to treat. Therefore, the search for new agents for its treatment is very important. 10-Hydroxycamptothecin (HCPT) was proved to have ideal anticancer activity in curing series cancer cells. In this study, the anticancer effect of HCPT on melanoma lung metastasis cancer was investigated by several administration routes, and whether the effect may be attributed to the induction of tumor cells apoptosis was determined. MTT assay results showed that HCPT exhibited selective cytotoxic activity against B16-F10 cells in a concentration- and time-dependent manner. Hoechst 33258 staining and transmission electron microscopy showed typical apoptotic morphology such as condensed chromatin, irregular nuclei, and apoptotic body formation. Flow cytometry analysis indicated a growth on apoptotic cells and a cell-cycle arrest in S phase after treatment with HCPT. In vivo melanoma pulmonary metastases were inhibited by treatment with HCPT. A more significant inhibition was observed if HCPT was administered by aerosol inhalation than that given by i.v. or i.p. administration. Thus, HCPT exhibited potential anticancer activity against B16-F10 cells in vitro and in vivo. However, the possible mechanisms involved still need to be investigated to explain this behavior.

Targeted nanoparticles deliver siRNA to melanoma

Melanoma is a severe skin cancer that often leads to death. To examine the potential of small interfering RNA (siRNA) therapy for melanoma, we have developed anisamide-targeted nanoparticles that can systemically deliver siRNA into the cytoplasm of B16F10 murine melanoma cells, which express the sigma receptor. A c-Myc siRNA delivered by the targeted nanoparticles effectively suppressed c-Myc expression in the tumor and partially inhibited tumor growth. More significant tumor growth inhibition was observed with nanoparticles composed of N,N-distearyl-N-methyl-N-2-(N'-arginyl) aminoethyl ammonium chloride (DSAA), a guanidinium-containing cationic lipid, than with a commonly used cationic lipid, 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP). Three daily injections of c-Myc siRNA formulated in the targeted nanoparticles containing DSAA could impair tumor growth, and the ED(50) of c-Myc siRNA was about 0.55  mg  kg(-1). The targeted DSAA nanoparticles containing c-Myc siRNA sensitized B16F10 cells to paclitaxel (Taxol), resulting in a complete inhibition of tumor growth for 1 week. Treatments of c-Myc siRNA in the targeted nanoparticles containing DSAA also showed significant inhibition on the growth of MDA-MB-435 tumor. The enhanced anti-melanoma activity is probably related to the fact that DSAA, but not DOTAP, induced reactive oxygen species, triggered apoptosis, and downregulated antiapoptotic protein Bcl-2 in B16F10 melanoma cells. Thus, the targeted nanoparticles containing c-Myc siRNA may serve as an effective therapeutic agent for melanoma.

Capsaicin induces apoptosis through ubiquitin-proteasome system dysfunction

Capsaicin is an active component of red pepper having an antiproliferative effect in a variety of cancer cells, which recent evidence suggests due to its ability to induce apoptosis. However, the molecular mechanisms through which capsaicin induces apoptosis are not well understood. Here we demonstrate that capsaicin-induced apoptosis is mediated via the inhibition cellular proteasome function. Treatment of capsaicin to mouse neuro 2a cells results in the inhibition of proteasome activity in a dose- and time-dependent manner that seems to correlate with its effect on cell death. The effect of capsaicin on cellular proteasome function is indirect and probably mediated via the generation of oxidative stress. Exposure of capsaicin also causes increased accumulation of ubiquitinated proteins as wells as various target substrates of proteasome like p53 and Bax and p27. Like many other classical proteasome inhibitors, capsaicin also triggers the intrinsic pathway of apoptosis involving mitochondria and induces neurite outgrowth. Our results strongly support for the use of capsaicin as an anticancer drug.

Capsaicin-induced apoptosis is regulated by endoplasmic reticulum stress- and calpain-mediated mitochondrial cell death pathways

Capsaicin, a pungent compound found in hot chili peppers, induces apoptotic cell death in various cell lines, however, the precise apoptosis signaling pathway is unknown. Here, we investigated capsaicin-induced apoptotic signaling in the human breast cell line MCF10A and found that it involves both endoplasmic reticulum (ER) stress and calpain activation. Capsaicin inhibited growth in a dose-dependent manner and induced apoptotic nuclear changes in MCF10A cells. Capsaicin also induced degradation of tumor suppressor p53; this effect was enhanced by the ER stressor tunicamycin. The proteasome inhibitor MG132 completely blocked capsaicin-induced p53 degradation and enhanced apoptotic cell death. Capsaicin treatment triggered ER stress by increasing levels of IRE1, GADD153/Chop, GRP78/Bip, and activated caspase-4. It led to an increase in cytosolic Ca(2+), calpain activation, loss of the mitochondrial transmembrane potential, release of mitochondrial cytochrome c, and caspase-9 and -7 activation. Furthermore, capsaicin-induced the mitochondrial apoptotic pathway through calpain-mediated Bid translocation to the mitochondria and nuclear translocation of apoptosis-inducing factor (AIF). Capsaicin-induced caspase-9, Bid cleavage, and AIF translocation were blocked by calpeptin, and BAPTA and calpeptin attenuated calpain activation and Bid cleavage. Thus, both ER stress- and mitochondria-mediated death pathways are involved in capsaicin-induced apoptosis.

Gallic acid ester derivatives induce apoptosis and cell adhesion inhibition in melanoma cells: The relationship between free radical generation, glutathione depletion and cell death

Malignant melanoma is a lethal disease, and the incidence and mortality associated with it are increasing worldwide. It has a significant tendency to develop both metastasis and resistance to chemotherapy. The tumor cells show abnormal redox regulation, and although the molecular mechanisms involved are not well characterized, they seem to be related to oxidative stress. In a previous study, we showed the antitumoral properties of gallic acid ester derivatives in leukemia cells. Here, we show the effect of octyl, decyl, dodecyl and tetradecyl gallates on B16F10 cells, a melanoma cell line. All compounds induced cytotoxic effects, and the IC(50) values obtained were between 7microM and 17microM after 48h of incubation. Cell death occurred through apoptosis, as demonstrated by the genomic DNA fragmentation pattern. The gallates were able to induce significant production of free radicals, deplete both glutathione and ATP, activate NF-kappaB and promote the inhibition of cell adhesion under the experimental conditions. The glutathione depletion induced by these compounds was related to the inhibition of gamma-glutamylcysteine synthase activity. These results suggest that gallates induce tumoral cell death through apoptosis as a consequence of oxidative stress, though they use different mechanisms to do so. These findings are important since melanoma cells are resistant to death because of their high level of antioxidant defense, adhesion capability and propensity to metastasize.

Fas-associated factor 1 is a negative regulator in capsaicin induced cancer cell apoptosis

Vanilloid receptor1 (VR1/TRPV1) is expressed on peripheral nerves and involved in sensing of temperature and pain. Recent reports have demonstrated that tumor cells express TRPV1 and that capsaicin (CP), a ligand for TRPV1, induces apoptosis in cancer cells. The mechanism underlying CP-induced tumor cell apoptosis remains unclear. Here, we investigated the role of TRPV1 in tumor apoptosis using TRPV1-expressing cancer cell lines. We demonstrate that iodo-resiniferatoxin (I-RTX), an antagonist of TRPV1 does not inhibit CP mediated apoptosis nor is it cytotoxic by itself, but acts as a partial agonist and shows synergistic effect with CP. We further demonstrate that CP treatment degrades Fas-associated factor1 (FAF1); a TRPV1 associated protein. Moreover, using RNA interference with small inhibitory RNAs (siRNA) for FAF1 we observed that down-regulation of FAF1 by siRNA makes the cell susceptible to enhanced apoptosis with CP. In summary, our data shows for the first time that the underlying mechanisms of CP-induced cancer cell apoptosis involves FAF1, a TRPV1 associated protein and serves as an important foundation for further understanding of anticancer activity of CP.

Inhibitory effect of capsaicin on B16-F10 melanoma cell migration via the phosphatidylinositol 3-kinase/Akt/Rac1 signal pathway

Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide), the major pungent ingredient of red pepper, has been reported to possess anti-carcinogenic and anti-mutagenic activities. In this study, the anti-migration activity of capsaicin on highly metastatic B16-F10 melanoma cells was investigated. Capsaicin significantly inhibited the migration of melanoma cells without showing obvious cellular cytotoxicity at low doses. This effect correlated with the down-regulation of phosphatidylinositol 3-kinase (PI3-K) and its downstream target, Akt. Although B16-F10 cell migration was increased by the PI3-K activator through the activation of Akt, these PI3-K activator-induced phenomena were attenuated by capsaicin. Moreover, capsaicin was found to significantly inhibit Rac1 activity in a pull-down assay. These results demonstrate that capsaicin inhibits the migration of B16-F10 cells through the inhibition of the PI3-K/Akt/Rac1 signal pathway. The present investigation suggests that capsaicin targets PI3-K/Akt/ Rac1-mediated cellular events in B16-F10 melanoma cells. Consequently, capsaicin administration should be considered an effective approach for the suppression of invasion and metastasis in malignant melanoma chemotherapy.

Spermatogonial stem cell sensitivity to capsaicin: an in vitro study

BACKGROUND

Conflicting reports have been published on the sensitivity of spermatogenesis to capsaicin (CAP), the pungent ingredient of hot chili peppers. Here, the effect of CAP on germ cell survival was investigated by using two testis germ cell lines as a model. As CAP is a potent agonist of the transient receptor potential vanilloid receptor 1 (TRPV1) and no information was available of its expression in germ cells, we also studied the presence of TRPV1 in the cultured cells and in germ cells in situ.

METHODS

The rat spermatogonial stem cell lines Gc-5spg and Gc-6spg were used to study the effects of different concentrations of CAP during 24 and 48 h. The response to CAP was first monitored by phase-contrast microscopy. As germ cells appear to undergo apoptosis in the presence of CAP, the activation of caspase 3 was studied using an anti activated caspase 3 antibody or by quantifying the amount of cells with DNA fragmentation using flow cytometry. Immunolocalization was done with an anti-TRPV1 antibody either with the use of confocal microscopy to follow live cell labeling (germ cells) or on Bouin fixed paraffin embedded testicular tissues. The expression of TRPV1 by the cell lines and germ cells was confirmed by Western blots.

RESULTS

Initial morphological observations indicated that CAP at concentrations ranging from 150 uM to 250 uM and after 24 and 48 h of exposure, had deleterious apoptotic-like effects on both cell lines: A large population of the CAP treated cell cultures showed signs of DNA fragmentation and caspase 3 activation. Quantification of the effect demonstrated a significant effect of CAP with doses of 150 uM in the Gc-5spg cell line and 200 uM in the Gc-6spg cell line, after 24 h of exposure. The effect was dose and time dependent in both cell lines. TRPV1, the receptor for CAP, was found to be expressed by the spermatogonial stem cells in vitro and also by premeiotic germ cells in situ.

CONCLUSION

CAP adversely affects spermatogonial survival in vitro by inducing apoptosis to those cells and TRPV-1, a CAP receptor, may be involved in this effect as this receptor is expressed by mitotic germ cells.

Capsaicin induces apoptosis and terminal differentiation in human glioma A172 cells

Capsaicin (8-methyl-N-vanillyl-6-nonenamide), the major pungent ingredient of red pepper, has been reported to possess anti-carcinogenic and anti-mutagenic activities. In this study, the effects of capsaicin on human glioblastoma A172 cells were investigated. Treatment of A172 cells with capsaicin inhibited cell growth and induced apoptosis through down-regulation of Bcl-2 and activation of caspase-3. Interestingly, synergistic induction of morphological alternation was observed when A172 cells were treated with capsaicin. A double immunostaining analysis indicated that capsaicin stimulated terminal differentiation predominantly to astrocyte-like cells. Moreover, capsaicin increased the transcription levels of glial fibrillary acidic protein (GFAP) and neuronal microtubule-associated protein 2ab (MAP2ab). These results demonstrated that capsaicin inhibits A172 cell growth through apoptosis and terminal differentiation. Consequently, this research may provide further support for capsaicin-based anti-tumor therapies and consideration should be given to developing capsaicin for use in chemotherapy for malignant human glioblastoma.