Capsaicin Induces Apoptosis Research Articles

Capsaicin induces cytotoxicity in human osteosarcoma MG63 cells through TRPV1-dependent and -independent pathways

ABSTRACTAn accumulating body of evidence has shown that capsaicin induces apoptosis in various tumor cells as a mechanism of its anti-tumor activity. However, the effects of capsaicin on osteosarcoma have not been studied extensively. In the current study, we explore the molecular mechanism of capsaicin-mediated tumor suppressive function in osteosarcoma. We found that capsaicin-induced apoptosis and the activation of transient receptor potential receptor vanilloid 1 (TRPV1) in a dose- and time-dependent manner in human osteosarcoma MG63 cells in vitro. Blocking TRPV1 using capsazepine attenuated the capsaicin-induced cytotoxicity, mitochondrial dysfunction, overproduction of reactive oxygen species (ROS) and decrease in superoxide dismutase (SOD) activity. In addition, the results demonstrated that capsaicin induced the activation of adenosine 5ʹ-monophosphate-activated protein kinase (AMPK), p53 and C-jun N-terminal kinase (JNK). In addition, Compound C (antagonist of AMPK) attenuated the activation of p53, which appeared to be TRPV1 independent. Taken together, the present study suggests that capsaicin effectively causes cell death in human osteosarcoma MG63 cells via the activation of TRPV1-dependent (mitochondrial dysfunction, and overproduction of ROS and JNK) and TRPV1-independent (AMPK-p53) pathways. Thus, capsaicin may be a potential anti-osteosarcoma agent.

Capsaicin induces apoptosis in human small cell lung cancer via the TRPV6 receptor and the calpain pathway.

Capsaicin, the pungent ingredient of chili peppers, displays potent anti-neoplastic activity in a wide array of human cancer cells. The present manuscript examines the signaling pathways underlying the apoptotic activity of capsaicin in human small cell lung cancer (SCLC) in vitro and in vivo. Studies in neuronal cells show that capsaicin exerts its biological activity via the transient receptor potential vanilloid (TRPV) superfamily of cation-channel receptors. The TRPV family is comprised of six members (TRPV1-6). Capsaicin is a known agonist of the TRPV1 receptor. We observed that capsaicin-induced apoptosis in human SCLC cells was mediated via the TRPV receptor family; however it was independent of TRPV1. Surprisingly, the apoptotic activity of capsaicin required the TRPV6 receptor. Depletion of TRPV6 receptor by siRNA methodology abolished the apoptotic activity of capsaicin in SCLC cells. Immunostaining and ELISA showed that TRPV6 receptor was robustly expressed on human SCLC tissues (from patients) and SCLC cell lines but almost absent in normal lung tissues. This correlates with our results that capsaicin induced very little apoptosis in normal lung epithelial cells. The pro-apoptotic activity of capsaicin was mediated by the intracellular calcium and calpain pathway. The treatment of human SCLC cells with capsaicin increased the activity of calpain 1 and 2 by threefold relative to untreated SCLC cells. Such calpain activation, in response to capsaicin, was downstream of the TRPV6 receptor. Taken together, our data provide insights into the mechanism underlying the apoptotic activity of capsaicin in human SCLCs.

Capsaicin induces apoptosis in MG63 human osteosarcoma cells via the caspase cascade and the antioxidant enzyme system

Osteosarcoma is the most common malignant bone tumor in children and adolescents. This aggressive cancer mostly occurs in the long bones. Therefore, novel therapeutic approaches, such as biological therapies and gene therapy, are required to efficiently treat osteosarcoma. Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) has been demonstrated to inhibit the growth of several types of cancer cells and a number of studies have shown that osteosarcoma may be vulnerable to biological therapies. However, little is known regarding the therapeutic effects of capsaicin on osteosarcoma. This study investigated the effects of capsaicin on MG63 human osteosarcoma cells, in addition to elucidating the regulatory signaling pathways underlying the effects of capsaicin, the caspase cascade and the antioxidant enzyme system. The MG63 cell line was treated with various concentrations of capsaicin. Cells were analyzed using MTT and flow cytometry, and the presence of DNA fragmentation was evaluated using TUNEL assay. Results showed capsaicin induced apoptosis in MG63 cells. Thus, capsaicin exhibited an anticancer effect in osteosarcoma cells.

Capsaicin-Induced Apoptosis of FaDu Human Pharyngeal Squamous Carcinoma Cells

PurposeTo investigate the anti-tumor effect of capsaicin on human pharyngeal squamous carcinoma cells (FaDu).Materials and MethodsThe expression of apoptosis/cell cycle-related proteins (or genes) was examined by reverse transcriptase-polymerase chain reaction, western blotting and ELISA methods, while the apoptotic cell population, cell morphology and DNA fragmentation levels were assessed using flow cytometry, fluorescence microscopy and agarose gel electrophoresis.ResultsCapsaicin was found to inhibit the growth and proliferation of FaDu cells in a dose- and time-dependent manner. Apoptotic cell death was confirmed by observing increases in nuclear condensation, nuclear DNA fragmentation and sub-G1 DNA content. The observed increase in cytosolic cytochrome c, activation of caspase 3 and PARP (p85) levels following capsaicin treatment indicated that the apoptotic response was mitochondrial pathway-dependent. Gene/protein expression analysis of Bcl-2, Bad and Bax further revealed decreased anti-apoptotic Bcl-2 protein and increased pro-apoptotic Bad/Bax expression. Furthermore, capsaicin suppressed the cell cycle progression at the G1/S phase in FaDu cells by decreasing the expression of the regulators of cyclin B1 and D1, as well as cyclin-dependent protein kinases cdk-1, cdk-2 and cdk-4.ConclusionOur current data show that capsaicin induces apoptosis in FaDu cells and this response is associated with mitochondrial pathways, possibly by mediating cell cycle arrest at G1/S.

Capsaicin induces apoptosis in SCC‐4 human tongue cancer cells through mitochondria‐dependent and ‐independent pathways

Although there have been advances in the fields of surgery, radiotherapy, and chemotherapy of tongue cancer, the cure rates are still not substantially satisfactory. Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) is the major pungent ingredient of hot chili pepper and has been reported to have an antitumor effect on many human cancer cell types. The molecular mechanisms of the antitumor effect of capsaicin are not yet completely understood. Herein, we investigated whether capsaicin induces apoptosis in human tongue cancer cells. Capsaicin decreased the percentage of viable cells in a dose-dependent manner in human tongue cancer SCC-4 cells. In addition, capsaicin produced DNA fragmentation, decreased the DNA contents (sub-G1 phase), and induced G0/G1 phase arrest in SCC-4 cells. We demonstrated that capsaicin-induced apoptosis is associated with an increase in reactive oxygen species and Ca²⁺ generations and a disruption of the mitochondrial transmenbrane potential (ΔΨ(m)). Treatment with capsaicin induced a dramatic increase in caspase-3 and -9 activities, as assessed by flow cytometric methods. A possible mechanism of capsaicin-induced apoptosis is involved in the activation of caspase-3 (one of the apoptosis-executing enzyme). Confocal laser microscope examination also showed that capsaicin induced the releases of AIF, ATF-4, and GADD153 from mitochondria of SCC-4 cells.

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 induces apoptosis by generating reactive oxygen species and disrupting mitochondrial transmembrane potential in human colon cancer cell lines

Although genetic factors are a well-known cause of colorectal cancer, environmental factors contribute more to its development. Despite advances in the fields of surgery, radiotherapy and chemotherapy, the cure rates for colon cancer have not substantially improved over the past few decades. Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide), the principal pungent ingredient of hot chili pepper, has exhibited an anti-tumor effect in many cell types. However, the mechanisms responsible for the anti-tumor effect of capsaicin are not yet completely understood. In this study, we investigated whether capsaicin induces apoptosis in colon cancer cell lines. Capsaicin decreased cell viability in a dose-dependent manner in Colo320DM and LoVo cells. In addition, capsaicin produced cell morphology changes and DNA fragmentation, decreased the DNA contents, and induced phosphatidylserine translocation, which is a hallmark of apoptotic cell death. We showed that capsaicin-induced apoptosis is associated with an increase in ROS generation and a disruption of the mitochondrial transmenbrane potential. A possible mechanism of capsaicin-induced apoptosis is the activation of caspase 3, a major apoptosis-executing enzyme. Treatment with capsaicin induced a dramatic increase in caspase 3 activity, as assessed by the cleavage of Ac-DEVD-AMC, a fluorogenic substrate. In conclusion, our results clearly showed that capsaicin induced apoptosis in colon cancer cells. Although the actual mechanisms of capsaicin-induced apoptosis remain uncertain, it may be a beneficial agent for colon cancer treatment and chemoprevention.

TRPV6 mediates capsaicin-induced apoptosis in gastric cancer cells—Mechanisms behind a possible new “hot” cancer treatment

Capsaicin is an organic compound in chili peppers which are consumed by over one quarter of the world's population daily. Studies have shown that capsaicin can induce apoptosis in some cancer cells by unknown mechanisms. In this study, both gastric cancer and normal epithelial cells were treated with capsaicin and examined for apoptosis by Annexin V binding. Our results showed that capsaicin induces apoptosis in both cells, although cancer cells are more susceptible. This susceptibility is dependent on the availability of TRPV6, a calcium-selective channel protein, as overexpression of TRPV6 in normal cells increased capsaicin-induced apoptosis and knockdown of TRPV6 in cancer cells suppressed this action. Our results further demonstrated that capsaicin increases mitochondrial permeability through activation of Bax and p53 in a JNK-dependent manner. Conclusions: (1) TRPV6, rather than TRPV1 (the well-known capsaicin receptor), mediates capsaicin-induced apoptosis in gastric cells; (2) abundance of TRPV6 in gastric cells determines their live or death under capsaicin treatment; and (3) capsaicin induces apoptosis by stabilization of p53 through JNK activation. Together, our data suggest that capsaicin may be a promising dietary candidate for cancer chemoprevention.

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

Capsaicin (8-methyl- N-vanillyl-6-nonenamide), a pungent ingredient of hot chili peppers, has been reported to possess substantial anticarcinogenic and antimutagenic activities. In the present study, we investigated the effect of capsaicin on induction of apoptosis in highly metastatic B16-F10 murine melanoma cells. Capsaicin inhibited growth of B16-F10 cells in a concentration-dependent manner. Proapoptotic effect of capsaicin was evidenced by nuclear condensation, internucleosomal DNA fragmentation, in situ terminal nick-end labeling of fragmented DNA (TUNEL), and an increased sub G1 fraction. Treatment of B16-F10 cells with capsaicin caused release of mitochondrial cytochrome c, activation of caspase-3, and cleavage of poly (ADP-ribose) polymerase in a dose-dependent manner. Furthermore, Bcl-2 expression in the B16-F10 cells was slightly down-regulated by capsaicin treatment. In contrast, there were no alterations in the levels of Bax in capsaicin-treated cells. Collectively, these findings indicate that capsaicin-induces apoptosis of B16-F10 melanoma cells via down-regulation the Bcl-2.

Involvement of caspase cascade in capsaicin-induced apoptosis of dorsal root ganglion neurons

Capsaicin induces apoptosis in some types of neurons, but the exact molecular mechanism remains unclear. In this study, capsaicin was systemically administrated in newborn rats and the dorsal root ganglion (DRG) neurons were examined for caspase-immunoreactivity. Capsaicin-induced neuronal apoptosis was revealed by TUNEL. TUNEL-positive neurons rapidly increased, reaching the peak at 24 h post-injection when 10.6% of DRG neurons were apoptotic. Neurons expressing immunoreactivity for activated caspases-9 and -3 concomitantly increased. At 24 h, 15.9% and 17.7% of DRG neurons exhibited immunoreactivity for caspase-9 and caspase-3, respectively. DNA fragmentation signal and caspase-immunoreactivity were detected in less than 0.5% of DRG neurons of vehicle control rats. The immunoreactivity and TUNEL-positivity returned to the vehicle control level by 120 h. Double label immunohistochemistry revealed co-expression of caspase-9 and DNA fragmentation or caspase-3 and DNA fragmentation. These results suggest that the caspase cascade is involved in the primary neuronal apoptosis induced by neurotoxin capsaicin.

Involvement of peroxynitrite in capsaicin-induced apoptosis of C6 glioma cells

Capsaicin induces apoptosis in some types of cells, but its mechanism remains obscure. In this study, peroxynitrite, a powerful oxidant generated from the reaction of superoxide and nitric oxide (NO) in biological system, was demonstrated to be responsible for capsaicin-mediated apoptosis in C6 glioma cells. Capsaicin-induced apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, and also identified by Annexin V staining and comet assay. Capsazepine and ruthenium red, the vanilloid receptor 1 (VR1/TPRV1) antagonists, did not inhibit capsaicin-induced apoptosis. Exposure to capsaicin not only promoted the generation of superoxide and iNOS, but also markedly suppressed the expression of SODs. Nitrite and nitrate, the NO metabolites accumulated in the medium, and the nitrotyrosine was also increased in proteins of C6 glioma cells exposed to capsaicin. Pretreatment of cells with 4 microM ebselen (a peroxynitrite scavenger) showed effective inhibitory effect on the capsaicin-induced apoptosis. These results suggest that peroxynitrite can act as a potential mediator in the capsaicin-induced apoptosis in C6 glioma cells.