capsazepine and Prostatic-Neoplasms

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.

Topics: A549 Cells; Animals; Antineoplastic Agents; Apoptosis; Capsaicin; Cell Line, Tumor; Cell Proliferation; Cell Survival; Enzyme Activation; Humans; Janus Kinase 1; Ki-67 Antigen; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Invasiveness; Phosphorylation; Prostatic Neoplasms; Protein Tyrosine Phosphatases; Receptor-Like Protein Tyrosine Phosphatases, Class 4; RNA Interference; RNA, Small Interfering; STAT3 Transcription Factor; Vanadates; Xenograft Model Antitumor Assays

Capsaicin (8-methyl-N-vanillyl-6-nonenamide), a constituent of green and red peppers, has been linked with suppression of tumorigenesis through a mechanism that is not well understood. In the present study, we examined the effects of capsaicin on the production of the cytokine interleukin (IL)-6 by PC-3 cells at both protein and mRNA levels which were evaluated by ELISA and real-time PCR, respectively. Capsaicin-treated PC-3 cells increased the synthesis and secretion of IL-6 which was abrogated by the transient receptor potential vanilloid receptor subtype 1 (TRPV1) antagonist capsazepine, as well as by inhibitors of PKC-α, phosphoinositol-3 phosphate kinase (PI-3K), Akt and extracellular signal-regulated protein kinase (ERK). We analyzed the role of capsaicin in the tumor necrosis factor (TNF)-α secretion by PC-3 cells which was increased at shorter times than IL-6 production. Furthermore, incubation of PC-3 cells with an anti-TNF-α antibody blocked the capsaicin-induced IL-6 secretion. These results raise the possibility that capsaicin-mediated IL-6 increase in prostate cancer PC-3 cells is regulated at least in part by TNF-α secretion and signaling pathway involving Akt, ERK and PKC-α activation.

Topics: Capsaicin; Carcinoma; Cell Line, Tumor; Cell Survival; Enzyme-Linked Immunosorbent Assay; Extracellular Signal-Regulated MAP Kinases; Humans; Interleukin-6; Male; Phosphatidylinositol 3-Kinases; Prostatic Neoplasms; Signal Transduction; TRPV Cation Channels; Tumor Necrosis Factor-alpha

Capsazepine has been widely used as a selective antagonist of vanilloid type 1 receptors; however, its other in vitro effect on most cell types is unknown. In human PC3 prostate cancer cells, the effect of capsazepine on intracellular Ca(2+) concentrations ([Ca(2+)](i)) and cytotoxicity was investigated by using fura-2 and tetrazolium, respectively. Capsazepine caused a rapid rise in [Ca(2+)](i) in a concentration-dependent manner with an EC(50) value of 75 microM. Capsazepine-induced [Ca(2+)](i) rise was reduced by 60% by removal of extracellular Ca(2+), suggesting that the capsazepine-induced [Ca(2+)](i) rise was contributed by extracellular Ca(2+) influx and intracellular Ca(2+). Consistently, the capsazepine (200 microM)-induced [Ca(2+)](i) rise was decreased by La(3+) by half. In Ca(2+)-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, caused a monophasic [Ca(2+)](i) rise, after which the effect of capsazepine on [Ca(2+)](i) was inhibited by 80%. Conversely, pretreatment with capsazepine partly reduced thapsigargin-induced [Ca(2+)](i) rise. U73122, an inhibitor of phospholipase C, abolished histamine (an inositol 1,4,5-trisphosphate-dependent Ca(2+) mobilizer)-induced, but not capsazepine-induced, [Ca(2+)](i) rise. These findings suggest that in human PC3 prostate cancer cells, capsazepine increases [Ca(2+)](i) by evoking Ca(2+) influx and releasing Ca(2+) from the endoplasmic reticulum via a phospholiase C-independent manner. Overnight incubation with capsazepine (200 microM) killed 37% of cells, which could not be prevented by chelating intracellular Ca(2+) with BAPTA.

Topics: Calcium; Capsaicin; Cell Line, Tumor; Cell Proliferation; Cytosol; Dose-Response Relationship, Drug; Egtazic Acid; Humans; Male; Prostatic Neoplasms; TRPV Cation Channels; Type C Phospholipases

Capsaicin, the pungent ingredient of hot chilli pepper, has been recently shown to induce apoptosis in several cell lines through a not well known mechanism. Here, we investigated the role of the vanilloid capsaicin in the death regulation of the human cancer androgen-resistant cell line PC-3. Capsaicin inhibited the growth of PC-3 with an IC(50) of 20 microM cells and induced cell apoptosis, as assessed by flow cytometry and nuclei staining with DAPI. Capsaicin induced apoptosis in prostate cells by a mechanism involving reactive oxygen species generation, dissipation of the mitochondrial inner transmembrane potential (DeltaPsi(m)) and activation of caspase 3. Capsaicin-induced apoptosis was not reduced by the antagonist capsazepine in a dose range from 0.1 microM to 20 microM, suggesting a receptor-independent mechanism. To study the in vivo effects of capsaicinoids, PC-3 cells were grown as xenografts in nude mice. Subcutaneous injection of either capsaicin or capsazepine (5 mg/kg body weight) in nude mice suppressed PC-3 tumor growth in all tumors investigated and induced apoptosis of tumor cells. Our data show a role for capsaicin against androgen-independent prostate cancer cells in vitro and in vivo and suggest that capsaicin is a promising anti-tumor agent in hormone-refractory prostate cancer, which shows resistance to many chemotherapeutic agents.

Topics: Androgens; Animals; Apoptosis; Capsaicin; Cell Line, Tumor; Cell Proliferation; Drug Resistance, Neoplasm; Gene Expression; Humans; Male; Mice; Mice, Nude; Neoplasm Transplantation; Prostatic Neoplasms; Reactive Oxygen Species; Transplantation, Heterologous; TRPV Cation Channels

The Ca(2+)-permeable channel TRPM8 is thought to play an important role in the pathophysiology of prostate cancer. We have investigated the intracellular location of TRPM8 and its role as a Ca(2+)-permeable channel in an androgen-responsive and an androgen-insensitive prostate cancer cell line. We report evidence from immunofluorescence experiments that in the androgen-responsive LNCaP cell line, the TRPM8 protein is expressed in the endoplasmic reticulum and plasma membrane, acts as a Ca(2+)-permeable channel (assessed using Fura-2 to measure increases in the cytoplasmic Ca(2+) concentration) in each of these membranes, and is regulated by androgen. Although TRPM8 was detected in the androgen-insensitive PC-3 cell line, no evidence was obtained for regulation of its expression by androgen. The results of experiments using LNCaP cells, the TRPM8 antagonist capsazepine, and small interference RNA targeted to TRPM8 indicate that TRPM8 is required for cell survival. These results indicate that TRPM8 is an important determinator of Ca(2+) homeostasis in prostate epithelial cells and may be a potential target for the action of drugs in the management of prostate cancer.

Topics: Androgens; Apoptosis; Base Sequence; Calcium; Capsaicin; Cell Survival; DNA Primers; Humans; Immunohistochemistry; Ion Channels; Ion Transport; Male; Menthol; Neoplasm Proteins; Prostatic Neoplasms; Sequence Homology, Nucleic Acid; TRPM Cation Channels