Capsaicin inhibits preferentially the NADH oxidase and growth of transformed cells in culture

Morzeddhu: A Unique Example of a Traditional and Sustainable Typical Dish from Catanzaro

"Morzeddhu" in the local dialect of Catanzaro ("Morzello" in Italian) is an official typical dish of the capital of the Calabria region. It is a peasant dish, almost unknown at an international level, that labels, in an extraordinary way, the culinary identity of Catanzaro, a city founded around the X century. After America's discovery, its preparation was optimized and definitively fixed. Its recipe is strictly based on a cow's "fifth quarter" combined with spicy and typical Mediterranean vegetables. Remarkably, no pork meat is used, and when all traditional ingredients are included in the complex and quite long preparation of this special dish, it can deserve the title of "Illustrissimo". This review provides a scientific description of Illustrissimo, emphasizing its unique properties and connection to the circular economy, food security, and the Mediterranean diet. We also highlight its unique quality compared to other alternatives through an analysis of their nutritional facts and bioactive compounds. Nutritionally, offal and fifth quarter components are a rich source of high-quality protein, with lower levels of total fat and saturated fatty acids compared to other meat cuts. In essence, this dish offers a great example of a high-quality yet affordable meal, aligning perfectly with a Mediterranean diet.

Capsaicin: A chili pepper bioactive phytocompound with a potential role in suppressing cancer development and progression

Cancer profoundly influences morbidity and fatality rates worldwide. Patients often have dismal prognoses despite recent improvements in cancer therapy regimens. However, potent biomolecules derived from natural sources, including medicinal and dietary plants, contain biological and pharmacological properties to prevent and treat various human malignancies. Capsaicin is a bioactive phytocompound present in red hot chili peppers. Capsaicin has demonstrated many biological effects, including antioxidant, anti-inflammatory, antimicrobial, and anticarcinogenic capabilities. This review highlights the cellular and molecular pathways through which capsaicin exhibits antineoplastic activities. Our work also depicts the synergistic anticancer properties of capsaicin in conjunction with other natural bioactive components and approved anticancer drugs. Capsaicin inhibits proliferation in various cancerous cells, and its antineoplastic actions in numerous in vitro and in vivo carcinoma models impact oncogenesis, tumor-promoting and suppressor genes, and associated signaling pathways. Capsaicin alone or combined with other phytocompounds or approved antineoplastic drugs triggers cell cycle progression arrest, generating reactive oxygen species and disrupting mitochondrial membrane integrity, ultimately stimulating caspases and promoting death. Furthermore, capsaicin alone or in combination can promote apoptosis in carcinoma cells by enhancing the p53 and c-Myc gene expressions. In conclusion, capsaicin alone or in combination can have enormous potential for cancer prevention and intervention, but further high-quality studies are needed to firmly establish the clinical efficacy of this phytocompound.

Bis(chloroacetamidino)-Derived Heteroarene-Fused Anthraquinones Bind to and Cause Proteasomal Degradation of tNOX, Leading to c-Flip Downregulation and Apoptosis in Oral Cancer Cells

Simple Summary

New-generation anthraquinone derivatives attached with different heterocycles and bearing chloroacetamidines in the side chains have been synthesized to reduce side effects and drug resistance. In this study, we identified the cellular target of the studied compounds through ligand binding assays and in silico simulations. Our results illustrate that the studied compounds bound to and targeted the tumor-associated NADH oxidase (tNOX) in oral cancer cells. tNOX is a growth-related protein and is found to be expressed in cancer cells but not in non-transformed cells, and its knockdown by RNA interference in tumor cells overturns cancer phenotypes, supporting its role in cellular growth. We also identified that tNOX bound to the studied compounds and underwent degradation, which was correlated with apoptosis induction in oral cancer cells.

Abstract

Anthraquinone-based intercalating compounds, namely doxorubicin and mitoxantrone, have been used clinically based on their capacity to bind DNA and induce DNA damage. However, their applications have been limited by side effects and drug resistance. New-generation anthraquinone derivatives fused with different heterocycles have been chemically synthesized and screened for higher anticancer potency. Among the compounds reported in our previous study, 4,11-bis(2-(2-chloroacetamidine)ethylamino)anthra[2,3-b]thiophene-5,10-dione dihydrochloride (designated 2c) was found to be apoptotic, but the direct cellular target responsible for the cytotoxicity remained unknown. Here, we report the synthesis and anticancer properties of two other derivatives, 4,11-bis(2-(2-chloroacetamidine)ethylamino)naphtho[2,3-f]indole-5,10-dione dihydrochloride (2a) and 4,11-bis(2-(2-chloroacetamidine)ethylamino)-2-methylanthra[2,3-b]furan-5,10-dione dihydrochloride (2b). We sought to identify and validate the protein target(s) of these derivatives in oral cancer cells, using molecular docking simulations and cellular thermal shift assays (CETSA). Our CETSA results illustrate that these derivatives targeted the tumor-associated NADH oxidase (tNOX, ENOX2), and their direct binding downregulated tNOX in p53-functional SAS and p53-mutated HSC-3 cells. Interestingly, the compounds targeted and downregulated tNOX to reduce SIRT1 deacetylase activity and increase Ku70 acetylation, which triggers c-Flip ubiquitination and induces apoptosis in oral cancer cells. Together, our data highlight the potential value of these heteroarene-fused anthraquinones in managing cancer by targeting tNOX and augmenting apoptosis.

Phytocompounds from the medicinal and dietary plants: Multi-target agents for cancer prevention and therapy

Cervical cancer is the fourth leading cause of cancer death among women worldwide. Due to cervical cancer's high incidence and mortality, there is an unmet demand for effective diagnostic, therapeutic, and preventive agents. At present, the preferred treatment strategies for advanced metastatic cervical cancer include surgery, radiotherapy, and chemotherapy. However, cervical cancer is gradually developing resistance to chemotherapy, thereby reducing its efficacy. Over the last several decades, phytochemicals, a general term for compounds produced from plants, have gained attention for their role in preventing cervical cancer. This role in cervical cancer prevention has garnered attention on the medicinal properties of fruits and vegetables. Phytochemicals are currently being evaluated for their ability to block proteins involved in carcinogenesis and chemoresistance against cervical cancer. Chemoresistance to cancer drugs like cisplatin, doxorubicin, and 5-fluorouracil has become a significant limitation of drug-based chemotherapy. However, the combination of cisplatin with other phytochemicals has been identified as a promising alternative to subjugate cisplatin resistance. Phytochemicals are promising chemo-preventive and chemotherapeutic agents as they possess antioxidant, anti-inflammatory, and anti-proliferative potential against many cancers, including cervical cancer. Furthermore, the ability of the phytochemicals to modulate cellular signaling pathways through up and down regulation of various proteins has been claimed for their therapeutic potential. Phytochemicals also display a wide range of biological functions, including cell cycle arrest, apoptosis induction, inhibition of invasion, and migration in cervical cancer cells. Numerous studies have revealed the critical role of different signaling proteins and their signaling pathways in the pathogenesis of cervical cancer. Here, we review the ability of several dietary phytochemicals to alter carcinogenesis by modulating various molecular targets.

Capsaicin inhibits cell proliferation by enhancing oxidative stress and apoptosis through SIRT1/NOX4 signaling pathways in HepG2 and HL-7702 cells

Capsaicin could suppress the proliferation of cancer cells and inhibit many biochemical pathways associated with tumorigenesis and metastasis. This study investigates the effects of capsaicin in both hepatocellular carcinoma (HepG2) and normal hepatocytes (HL-7702) via the SIRT1/NOX4 signaling pathway. After determination of cytotoxic concentrations of capsaicin on HL-7702 and HepG2 cells, we measured total oxidant status (TOS), reduced glutathione (GSH), 8-hydroxydeoxyguanosine (8-OHdG), cytochrome c (CYC), caspase3 (CASP3), Bcl-2, Bax, sirtuin1 (SIRT1), and NADPH oxidases4 (NOX4) levels. Besides this, we analyzed the messenger RNA and protein levels of SIRT1 and NOX4. We found that capsaicin increased TOS, 8-OHdG, CASP3, CYC, Bax, and NOX4 levels, and decreased Bcl-2, GSH, and SIRT1 in a concentration-dependent manner in HepG2 cells. However, especially low capsaicin concentration (128.75 µM) enhanced GSH and SIRT levels and reduced TOS, CASP3, CYC, 8-OHdG, and NOX4 levels in HL-7702 cells (p < 0.05). Interestingly, 128.75 and 172.8 µM capsaicin treatment increased SIRT1 expression levels in HL-7702 cells, resulting in an increase in GSH levels and a decrease in TOS, CYC, CAPS3, and 8-OHdG levels through NOX4 inhibition. Furthermore, we demonstrated a significant decrease in SIRT1 protein levels and an increase in NOX4 protein levels and caspase-3/-7 activities in both HL-7702 and HepG2 cells treated with 261.5 µM capsaicin. Additionally, morphological changes in HL-7702 and HepG2 cells treated with capsaicin correlated with the enhancement in oxidative burden, DNA damage, and apoptosis. Our results show that capsaicin effectively might cause higher oxidative, apoptotic, and DNA damage in HepG2 cells than in HL-7702 cells through the SIRT1/NOX4 signaling pathway.

Capsaicin exerts therapeutic effects by targeting tNOX-SIRT1 axis and augmenting ROS-dependent autophagy in melanoma cancer cells

Although considered a sporadic type of skin cancer, malignant melanoma has regularly increased internationally and is a major cause of cancer-associated death worldwide. The treatment options for malignant melanoma are very limited. Accumulating data suggest that the natural compound, capsaicin, exhibits preferential anticancer properties to act as a nutraceutical agent. Here, we explored the underlying molecular events involved in the inhibitory effect of capsaicin on melanoma growth. The cellular thermal shift assay (CETSA), isothermal dose-response fingerprint curves (ITDRF_CETSA), and CETSA-pulse proteolysis were utilized to confirm the direct binding of capsaicin with the tumor-associated NADH oxidase, tNOX (ENOX2) in melanoma cells. We also assessed the cellular impact of capsaicin-targeting of tNOX on A375 cells by flow cytometry and protein analysis. The essential role of tNOX in tumor- and melanoma-growth limiting abilities of capsaicin was evaluated in C57BL/6 mice. Our data show that capsaicin directly engaged with cellular tNOX to inhibit its enzymatic activity and enhance protein degradation capacity. The inhibition of tNOX by capsaicin was accompanied by the attenuation of SIRT1, a NAD⁺-dependent deacetylase. The suppression of tNOX and SIRT1 then enhanced ULK1 acetylation and induced ROS-dependent autophagy in melanoma cells. Capsaicin treatment of mice implanted with melanoma cancer cells suppressed tumor growth by down-regulating tNOX and SIRT1, which was also seen in an in vivo xenograft study with tNOX-depleted melanoma cells. Taken together, our findings suggest that tNOX expression is important for the growth of melanoma cancer cells both in vitro and in vivo, and that inhibition of the tNOX-SIRT1 axis contributes to inducting ROS-dependent autophagy in melanoma cells.

Effects of yellow and red bell pepper (paprika) extracts on pathogenic microorganisms, cancerous cells and inhibition of survivin

The present work examined the biomedical value of red and yellow bell pepper extracts (YME and RME) in terms of antioxidant, antibacterial and anticancer activities by in vitro and virtual studies. The yield of extract was 3.49% for RME and 2.92% for YME. The level of total phenols and total flavonoids significantly varied between the type of extracts, and it was higher in RME than that in YME. The extracts showed promising DPPH and ABTS free radical scavenging rates. The extracts showed an excellent antibacterial activity. The minimal inhibitory concentration (MIC) of RME was 0.20 mg mL^-1 for Bacillus cereus, 0.30 mg mL^-1 for Escherichia coli, 0.50 mg mL^-1 for Staphylococcus aureus and 0.60 mg mL^-1 and for Pseudomonas aeruginosa, while the MIC of YME was 0.40 mg mL^-1 for B. cereus, 0.40 mg mL^-1 for E. coli, 0.50 mg mL^-1 for S. aureus, and 0.60 mg mL^-1 for P. aeruginosa. TEM results demonstrated the cellular damage induced by RME in B. cereus biofilm. The RME did not show any cytotoxicity in normal NIH3T3 cells, but at 125 μg mL^-1 did a strong cytotoxicity in human lung cancer cell line A549 as evident by cytotoxicity assay, ROS and AO/EB staining. The virtual biological examination indicated that β-carotene from RME was a potential compound with higher docking energy against both targeted enzymes and proteins as - 14.30 for LpxC and - 15.59 for survivin. Therefore, it is recommended that RME is a better functional food with novel biomedical properties and it deserves further evaluation for its the novel molecules against multidrug resistant pathogens.

Ras Signaling in Breast Cancer

Ras proteins mediate extracellular and cytoplasmic signaling networks via receptor tyrosine kinase. The Ras pathway induces activation of signaling molecules involved in cell proliferation and growth, cell survival and apoptosis, metabolism, and motility. Although Ras mutations in breast cancer are not frequently reported, hyperactivation of Ras signaling plays an important role in breast cancer growth and progression. Oncogenic Ras activation occurs via loss of Ras GTPase-activating proteins, overexpression of growth factor receptor, and stimulation by various cytokines. Effective control of oncogenic Ras is one of the therapeutic strategies in breast cancer. The mechanisms of intracellular localization, activation, and signaling pathway of Ras in cancer have been used to develop therapeutic candidates. Recent studies have reported an effective therapy for breast cancer by inhibition of enzymes involved in the posttranslational modification of Ras, such as farnesyltransferase and geranylgeranyltransferase 1, and anti-cancer therapies targeting the epidermal growth factor receptor (EGFR). Emerging targets involved in EGF-mediated Ras activity in breast cancer have shed new insight into Ras activation in breast cancer progression. These alternative mechanisms for Ras signaling pathway may suggest novel therapeutic approaches for targeting Ras in breast cancer. In spite of the difficulties in targeting Ras protein, important discoveries highlight the direct inhibition of Ras activity. Further studies may elucidate the effects of targeting Ras protein and the clinical relevance thereof.

Capsaicin acts through tNOX (ENOX2) to induce autophagic apoptosis in p53-mutated HSC-3 cells but autophagy in p53-functional SAS oral cancer cells

Despite the progress that has been made in diagnosing and treating oral cancers, they continue to have a poor prognosis, with a 5-year overall survival rate of approximately 50%. We have intensively studied the anticancer properties of capsaicin (a burning constituent of chili pepper), mainly focusing on its apoptotic properties. Here, we investigated the interplay between apoptosis and autophagy in capsaicin-treated oral cancer cells with either functional or mutant p53. Cytotoxicity was determined by cell impedance measurements and WST-1 assays, and cell death was analyzed by flow cytometry. The interaction between capsaicin and tumor-associated NADH oxidase (tNOX, ENOX2) was studied by cellular thermal shift assay (CETSA) and isothermal dose-response fingerprint curves (ITDRF_CETSA). Our CETSA data suggested that capsaicin directly engaged with tNOX, resulting in its degradation through the ubiquitin-proteasome and the autophagy-lysosome systems. In p53-functional SAS cells, capsaicin induced significant cytotoxicity via autophagy but not apoptosis. Given that tNOX catalyzes the oxidation of NADH, the direct binding of capsaicin to tNOX also inhibited the NAD⁺-dependent activity of sirtuin 1 (SIRT1) deacetylase, we found that capsaicin-induced autophagy involved enhanced acetylation of ULK1, which is a key player in autophagy activation, possibly through SIRT1 inhibition. In p53-mutated HSC-3 cells, capsaicin triggered both autophagy and apoptosis. In this case, autophagy occurred before apoptosis: during this early stage, autophagy seemed to inhibit apoptosis; at a later stage, in contrast, autophagy appeared to be essential for the induction of apoptosis. Western blot analysis revealed that the reduction in tNOX and SIRT1 associated with enhanced ULK1 acetylation and c-Myc acetylation, which in turn, reactivated the TRAIL pathway, ultimately leading to apoptosis. Taken together, our data highlight the potential value of leveraging capsaicin and tNOX in therapeutic strategies against oral cancer.

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.

Capsaicin Targets tNOX (ENOX2) to Inhibit G1 Cyclin/CDK Complex, as Assessed by the Cellular Thermal Shift Assay (CETSA)

Capsaicin (8-methyl-N-vanillyl-6-noneamide), which is an active component in red chili peppers, is used as a chemopreventive agent that shows favorable cytotoxicity against cancer cells. Accumulating evidence indicates that capsaicin preferentially inhibits a tumor-associated NADH oxidase (tNOX, ENOX2) that is ubiquitously expressed in cancer but not in non-transformed cells. This attenuates cancer cell growth by inducing apoptosis. The capsaicin-mediated inhibition of tNOX was recently shown to prolong the cell cycle. However, the molecular events underlying this regulation have not yet been investigated. In the present study, we used a cellular thermal shift assay (CETSA) to detect “target engagement” of capsaicin and its consequent impact on cell cycle progression. Our results indicated that capsaicin engaged with tNOX and triggered the proteasomal degradation of tNOX, which leads to the inhibition of NAD⁺-dependent SIRT1 deacetylase. Ultimately, the acetylation levels of c-Myc and p53 were enhanced, which suppressed the activation of G1 cyclin/Cyclin-dependent kinase complexes and triggered cell cycle arrest in cancer cells. The results obtained when tNOX was overexpressed in non-cancer cells validated its importance in cell cycle progression. These findings provide the first molecular insights into the regulatory role of tNOX and the anti-proliferative property of capsaicin in regulating the cell cycle of bladder cancer cells.

Immune response evoked by tumor-associated NADH oxidase (tNOX) confers potential inhibitory effect on lung carcinoma in a mouse model

Tumor-associated NADH oxidase (tNOX, ENOX2), which belongs to a family of growth-related NADH oxidases, was originally identified as a plasma membrane protein of rat hepatoma and is inhibited or downregulated by several anti-cancer drugs. The objective of this study was to evaluate the anti-tumor effects of tNOX used as an immunogen against Lewis lung cancer. Human tNOX was expressed in Escherichia coli, purified by His-Tag affinity chromatography, and emulsified with the adjuvant, ISA 201 VG. Immunological analyses of the generated tNOX vaccine were performed in mice. The results of ELISA and ELISpot were significantly higher in tNOX vaccine group compared to the control group. In vivo, we examined the anti-tumor effects of mice that received the tNOX vaccine via the intraperitoneal or subcutaneous routes. Mice were vaccinated three times at 2-week intervals, challenged at 2 weeks after the final vaccination, and terminated at 34 days post-challenge. Antibody titers, tumor volume and histopathological scores were used to evaluate the anti-tumor effects of the tNOX vaccine. Our results revealed that tNOX-vaccinated mice had significantly higher antibody titers than negative control (NC) and challenge control (CC) mice. When compared to the corresponding CC groups, the intraperitoneal and subcutaneous vaccination with tNOX showed a significantly smaller tumor mass volume (P < 0.05) and a significantly lower histological lesion score (P < 0.05), respectively. Our results demonstrate that the use of a xenogeneic tNOX as an immunogen in mice activates immune responses and anti-tumor effects against Lewis lung cancer.

Engagement with tNOX (ENOX2) to Inhibit SIRT1 and Activate p53-Dependent and -Independent Apoptotic Pathways by Novel 4,11-Diaminoanthra[2,3-b]furan-5,10-diones in Hepatocellular Carcinoma Cells

Hepatocellular carcinoma (HCC) is the most frequent primary malignancy of the liver and is among the top three causes of cancer-associated death worldwide. However, the clinical use of chemotherapy for HCC has been limited by various challenges, emphasizing the urgent need for novel agents with improved anticancer properties. We recently synthesized and characterized a series of 4,11-diaminoanthra[2,3-b]furan-5,10-dione derivatives that exhibit potent apoptotic activity against an array of cancer cell lines, including variants with multidrug resistance. Their effect on liver cancer cells, however, was unknown. Here, we investigated three selected 4,11-diaminoanthra[2,3-b]furan-5,10-dione derivatives (compounds 1–3) for their cytotoxicity and the underlying molecular mechanisms in wild-type or p53-deficient HCC cells. Cytotoxicity was determined by WST-1 assays and cell impedance measurements and apoptosis was analyzed by flow cytometry. The interaction between compounds and tumor-associated NADH oxidase (tNOX, ENOX2) was studied by cellular thermal shift assay (CETSA). We found that compound 1 and 2 induced significant cytotoxicity in both HepG2 and Hep3B lines. CETSA revealed that compounds 1 and 2 directly engaged with tNOX, leading to a decrease in the cellular NAD⁺/NADH ratio. This decreased the NAD⁺-dependent activity of Sirtuin 1 (SIRT1) deacetylase. In p53-wild-type HepG2 cells, p53 acetylation/activation was enhanced, possibly due to the reduction in SIRT1 activity, and apoptosis was observed. In p53-deficient Hep3B cells, the reduction in SIRT1 activity increased the acetylation of c-Myc, thereby reactivating the TRAIL pathway and, ultimately leading to apoptosis. These compounds thus trigger apoptosis in both cell types, but via different pathways. Taken together, our data show that derivatives 1 and 2 of 4,11-diaminoanthra[2,3-b]furan-5,10-diones engage with tNOX and inhibit its oxidase activity. This results in cytotoxicity via apoptosis through tNOX-SIRT1 axis to enhance the acetylation of p53 or c-Myc in HCC cells, depending on their p53 status.

Capsaicin Induces Apoptosis in KSHV-Positive Primary Effusion Lymphoma by Suppressing ERK and p38 MAPK Signaling and IL-6 Expression

Primary effusion lymphoma (PEL) is defined as a rare subtype of non-Hodgkin's B-cell lymphoma which is caused by Kaposi's sarcoma-associated herpesvirus (KSHV) in immunosuppressed patients. PEL is an aggressive lymphoma and is frequently resistant to conventional chemotherapies. Therefore, it is critical to investigate novel therapeutic options for PEL. Capsaicin is a pungent component of chili pepper and possesses unique pharmacological effects, such as pain relief, anti-microbial and anti-cancer properties. Here, we demonstrate that capsaicin markedly inhibited the growth of KSHV latently infected PEL cells by inhibiting ERK, p38 MAPK and expression hIL-6, which are known to contribute to PEL growth and survival. The underlying mechanism of action by capsaicin was through the inhibition of ERK and p38 MAPK phosphorylation and signaling that affected hIL-6 expression. As a result, capsaicin induced apoptosis in PEL cells in a caspase-9 dependent manner. In line with these results, ERK (U0126) and p38 MAPK (SB203580) specific signaling inhibitors suppressed hIL-6 expression and attenuated cell growth in PEL cells. Furthermore, the addition of hIL-6 neutralizing antibody to culture medium suppressed the growth of PEL cells. We also demonstrate that capsaicin suppressed PEL cell growth in the absence of nascent viral replication. Finally, we confirmed ex vivo treatment of capsaicin attenuated PEL development in SCID mice. Taken together, capsaicin could represent a lead compound for PEL therapy without the risk of de novo KSHV infection.

Regulation of tNOX expression through the ROS-p53-POU3F2 axis contributes to cellular responses against oxaliplatin in human colon cancer cells

BACKGROUND

Oxaliplatin belongs to the platinum-based drug family and has shown promise in treating cancer by binding to DNA to induce cytotoxicity. However, individual patients show diverse therapeutic responses toward oxaliplatin due to yet-unknown underlying mechanisms. We recently established that oxaliplatin also exert its anti-cancer activity in gastric cancer cell lines by targeting tumor-associated NADH oxidase (tNOX), attenuate NAD⁺ generation and reduce NAD⁺-dependent sirtuin 1 (SIRT1) deacetylase activity, which in turn enhances p53 acetylation and apoptosis.

METHODS

In this study, differential cellular outcomes in response to oxaliplatin exposure of p53-wild-type versus p53-null HCT116 human colon cancer cells were examined. Cell growth profile was determined by cell impedance measurements and apoptosis was analyzed by flow cytometry. The engagement between oxaliplatin and tNOX protein was studied by cellular thermal shift assay. Furthermore, western blot analysis revealed that p53 was important in regulating tNOX expression in these cell lines.

RESULTS

In p53-wild-type cells, we found that oxaliplatin inhibited cell growth by inducing apoptosis and concurrently down-regulating tNOX at both the transcriptional and translational levels. In p53-null cells, in contrast, oxaliplatin moderately up-regulated tNOX expression and yielded no apoptosis and much less cytotoxicity. Further experiments revealed that in p53-wild-type cells, oxaliplatin enhanced ROS generation and p53 transcriptional activation, leading to down-regulation of the transcriptional factor, POU3F2, which enhances the expression of tNOX. Moreover, the addition of a ROS scavenger reversed the p53 activation, POU3F2 down-regulation, and apoptosis induced by oxaliplatin in p53-wild-type cells. In the p53-null line, on the other hand, oxaliplatin treatment triggered less ROS generation and no p53 protein, such that POU3F2 and tNOX were not down-regulated and oxaliplatin-mediated cytotoxicity was attenuated.

CONCLUSION

Our results show that oxaliplatin mediates differential cellular responses in colon cancer cells depending on their p53 status, and demonstrate that the ROS-p53 axis is important for regulating POU3F2 and its downstream target, tNOX. Notably, the depletion of tNOX sensitizes p53-null cells to both spontaneous and oxaliplatin-induced apoptosis. Our work thus clearly shows a scenario in which targeting of tNOX may be a potential strategy for cancer therapy in a p53-inactivated system.

Research progress of capsaicin responses to various pharmacological challenges

Capsaicin, a well known vanilloid, has shown evidence of an ample variety of biological effects which make it the target of extensive research ever since its identification. In spite of the fact that capsaicin causes health hazards in quite a few ways, yet, the verity cannot be ignored that capsaicin has several therapeutic implications. In patients with hypersensitive bladders, vesical instillation of 1 mM capsaicin markedly improved urinary frequency and urge incontinence. Again, administration of capsaicin favors an augmentation in lipid mobilization and a decrease in adipose tissue mass. Topical capsaicin cream as well decreases postsurgical neuropathic pain and is preferred by patients over a placebo among other therapies. Several in vitro studies have revealed that capsaicin results in growth arrest in some transformed cell lines. Furthermore, capsaicin has been proven to be an undeniably exciting molecule and remains a valuable drug for alleviating pain and itch. It has been recognized that capsaicinoids are the most potential agonists of capsaicin receptor (TRPV1). However, vanilloids could exert the beneficial effects not only through the receptor-dependent pathway but also through the receptor-independent one. The involvement of serotonin, neuropeptide Substance P and somatostatin in the pharmacological actions of capsaicin has been expansively investigated. Better understanding of the established TRPV1 receptor mechanism as well as exploring other possible receptor mechanism may publicize other new clinical efficacies of capsaicin. Further, clinical studies are required in several of these conditions to establish the efficacy of capsaicin.

Tumor-associated NADH oxidase (tNOX)-NAD+-sirtuin 1 axis contributes to oxaliplatin-induced apoptosis of gastric cancer cells

Oxaliplatin belongs to the platinum-based drug family and has shown promise in cancer treatment. The major mechanism of action of platinum compounds is to form platinum–DNA adducts, leading to DNA damage and apoptosis. Accumulating evidence suggests that they might also target non-DNA molecules for their apoptotic activity. We explored the effects of oxaliplatin on a tumor-associated NADH oxidase (tNOX) in gastric cancer lines. In AGS cells, we found that the oxaliplatin-inhibited tNOX effectively attenuated the NAD⁺/NADH ratio and reduced the deacetylase activity of an NAD⁺-dependent sirtuin 1, thereby enhancing p53 acetylation and apoptosis. Similar results were also observed in tNOX-knockdown AGS cells. In the more aggressive MKN45 and TMK-1 lines, oxaliplatin did not inhibit tNOX, and induced only minimal apoptosis and cytotoxicity. However, the downregulation of either sirtuin 1 or tNOX sensitized TMK-1 cells to oxaliplatin-induced apoptosis. Moreover, tNOX-depletion in these resistant cells enhanced spontaneous apoptosis, reduced cyclin D expression and prolonged the cell cycle, resulting in diminished cancer cell growth. Together, our results demonstrate that oxaliplatin targets tNOX and SIRT1, and that the tNOX-NAD⁺-sirtuin 1 axis is essential for oxaliplatin-induced apoptosis.

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.

Capsaicin Inhibits Multiple Bladder Cancer Cell Phenotypes by Inhibiting Tumor-Associated NADH Oxidase (tNOX) and Sirtuin1 (SIRT1)

Bladder cancer is one of the most frequent cancers among males, and its poor survival rate reflects problems with aggressiveness and chemo-resistance. Recent interest has focused on the use of chemopreventatives (nontoxic natural agents that may suppress cancer progression) to induce targeted apoptosis for cancer therapy. Capsaicin, which has anti-cancer properties, is one such agent. It is known to preferentially inhibit a tumor-associated NADH oxidase (tNOX) that is preferentially expressed in cancer/transformed cells. Here, we set out to elucidate the correlation between tNOX expression and the inhibitory effects of capsaicin in human bladder cancer cells. We showed that capsaicin downregulates tNOX expression and decreases bladder cancer cell growth by enhancing apoptosis. Moreover, capsaicin was found to reduce the expression levels of several proteins involved in cell cycle progression, in association with increases in the cell doubling time and enhanced cell cycle arrest. Capsaicin was also shown to inhibit the activation of ERK, thereby reducing the phosphorylation of paxillin and FAK, which leads to decreased cell migration. Finally, our results indicate that RNA interference-mediated tNOX depletion enhances spontaneous apoptosis, prolongs cell cycle progression, and reduces cell migration and the epithelial-mesenchymal transition. We also observed a downregulation of sirtuin 1 (SIRT1) in these tNOX-knockdown cells, a deacetylase that is important in multiple cellular functions. Taken together, our results indicate that capsaicin inhibits the growth of bladder cancer cells by inhibiting tNOX and SIRT1 and thereby reducing proliferation, attenuating migration, and prolonging cell cycle progression.

Capsaicin Inhibited Aggressive Phenotypes through Downregulation of Tumor-Associated NADH Oxidase (tNOX) by POU Domain Transcription Factor POU3F2

Capsaicin has been reported to preferentially inhibit the activity of tumor-associated NADH oxidase (tNOX), which belongs to a family of growth-related plasma membrane hydroquinone oxidases in cancer/transformed cells. The inhibitory effect of capsaicin on tNOX is associated with cell growth attenuation and apoptosis. However, no previous study has examined the transcriptional regulation of tNOX protein expression. Bioinformatic analysis has indicated that the tNOX promoter sequence harbors a binding motif for POU3F2, which is thought to play important roles in neuronal differentiation, melanocytes growth/differentiation and tumorigenesis. In this study, we found that capsaicin-mediated tNOX downregulation and cell migration inhibition were through POU3F2. The protein expression levels of POU3F2 and tNOX are positively correlated, and that overexpression of POU3F2 (and the corresponding upregulation of tNOX) enhanced the proliferation, migration and invasion in AGS (human gastric carcinoma) cells. In contrast, knockdown of POU3F2 downregulates tNOX, and the cancer phenotypes are affected. These findings not only shed light on the molecular mechanism of the anticancer properties of capsaicin, but also the transcription regulation of tNOX expression that may potentially explain how POU3F2 is associated with tumorigenesis.

Update on a tumor-associated NADH oxidase in gastric cancer cell growth

Gastric cancer is one of the most common human malignancies, and its prevalence has been shown to be well-correlated with cancer-related deaths worldwide. Regrettably, the poor prognosis of this disease is mainly due to its late diagnosis at advanced stages after the cancer has already metastasized. Recent research has emphasized the identification of cancer biomarkers in the hope of diagnosing cancer early and designing targeted therapies to reverse cancer progression. One member of a family of growth-related nicotinamide adenine dinucleotide (NADH or hydroquinone) oxidases is tumor-associated NADH oxidase (tNOX; ENOX2). Unlike its counterpart CNOX (ENOX1), identified in normal rat liver plasma membranes and shown to be stimulated by growth factors and hormones, tNOX activity purified from rat hepatoma cells is constitutively active. Its activity is detectable in the sera of cancer patients but not in those of healthy volunteers, suggesting its clinical relevance. Interestingly, tNOX expression was shown to be present in an array of cancer cell lines. More importantly, inhibition of tNOX was well correlated with reduced cancer cell growth and induction of apoptosis. RNA interference targeting tNOX expression in cancer cells effectively restored non-cancerous phenotypes, further supporting the vital role of tNOX in cancer cells. Here, we review the regulatory role of tNOX in gastric cancer cell growth.

Capsaicin and Its Role in Chronic Diseases

A significant number of experimental and clinical studies published in peer-reviewed journals have demonstrated promising pharmacological properties of capsaicin in relieving signs and symptoms of non-communicable diseases (chronic diseases). This chapter provides an overview made from basic and clinical research studies of the potential therapeutic effects of capsaicin, loaded in different application forms, such as solution and cream, on chronic diseases (e.g. arthritis, chronic pain, functional gastrointestinal disorders and cancer). In addition to the anti-inflammatory and analgesic properties of capsaicin largely recognized via, mainly, interaction with the TRPV1, the effects of capsaicin on different cell signalling pathways will be further discussed here. The analgesic, anti-inflammatory or apoptotic effects of capsaicin show promising results in arthritis, neuropathic pain, gastrointestinal disorders or cancer, since evidence demonstrates that the oral or local application of capsaicin reduce inflammation and pain in rheumatoid arthritis, promotes gastric protection against ulcer and induces apoptosis of the tumour cells. Sadly, these results have been paralleled by conflicting studies, which indicate that high concentrations of capsaicin are likely to evoke deleterious effects, thus suggesting that capsaicin activates different pathways at different concentrations in both human and rodent tissues. Thus, to establish effective capsaicin doses for chronic conditions, which can be benefited from capsaicin therapeutic effects, is a real challenge that must be pursued.

Synthesis and Characterization of 4,11-Diaminoanthra[2,3-b]furan-5,10-diones: Tumor Cell Apoptosis through tNOX-Modulated NAD(+)/NADH Ratio and SIRT1

A series of new 4,11-diaminoanthra[2,3-b]furan-5,10-dione derivatives with different side chains were synthesized. Selected 2-unsubstituted derivatives 11-14 showed high antiproliferative potency on a panel of mammalian tumor cell lines including multidrug resistance variants. Compounds 11-14 utilized multiple mechanisms of cytotoxicity including inhibition of Top1/Top2-mediated DNA relaxation, reduced NAD(+)/NADH ratio through tNOX inhibition, suppression of a NAD(+)-dependent sirtuin 1 (SIRT1) deacetylase activity, and activation of caspase-mediated apoptosis. Here, for the first time, we report that tumor-associated NADH oxidase (tNOX) and SIRT1 are important cellular targets of antitumor anthracene-9,10-diones.

ENOX2 target for the anticancer isoflavone ME-143

ME-143 (NV-143), a synthetic isoflavone under clinical evaluation for efficacy in the management of ovarian and other forms of human cancer, blocked the activity of a cancer-specific and growth-related cell surface ECTO-NOX protein with both oxidative (hydroquinone) and protein disulfide-thiol interchange activity designated ENOX2 (tNOX) and inhibited the growth of cultured cancer cells with EC₅₀s in the range of 20–50 nM. Purified recombinant ENOX2 also bound ME-143 with a K_d of 43 (40–50) nM. Both the oxidative and protein disulfide-thiol interchange activities of ENOX proteins that alternate to generate a complex set of oscillations with a period length of 22 min compared to 24 min for the constitutive counterpart ENOX1 (CNOX) that characterizes ENOX proteins responded to ME-143. Oxidation of NADH or reduced coenzyme Q₁₀ was rapidly blocked. In contrast, the protein disulfide-thiol interchange activity measured from the cleavage of dithiodipyridine (EC₅₀ of ca. 50 nM) was inhibited progressively over an interval of 60 min that spanned three cycles of activity. Inhibition of the latter paralleled the inhibition of cell enlargement and the consequent inability of inhibited cells to initiate traverse of the cell cycle. Activities of constitutive ENOX1 (CNOX) forms of either cancer or noncancer cells were unaffected by ME-143 over the range of concentrations inhibiting ENOX2. Taken together, the findings show that ME-143 binds to ENOX2 with an affinity 4 to 10 times greater than that reported previously for the related anticancer isoflavone, phenoxodiol.

Sirtuin 1 (SIRT1) Deacetylase Activity and NAD⁺/NADH Ratio Are Imperative for Capsaicin-Mediated Programmed Cell Death

Capsaicin is considered a chemopreventive agent by virtue of its selective antigrowth activity, commonly associated with apoptosis, against cancer cells. However, noncancerous cells possess relatively higher tolerance to capsaicin, although the underlying mechanism for this difference remains unclear. Hence, this study aimed to elucidate the differential effects of capsaicin on cell lines from lung tissues by addressing the signal pathway leading to two types of cell death. In MRC-5 human fetal lung cells, capsaicin augmented silent mating type information regulation 1 (SIRT1) deacetylase activity and the intracellular NAD(+)/NADH ratio, decreasing acetylation of p53 and inducing autophagy. In contrast, capsaicin decreased the intracellular NAD(+)/NADH ratio, possibly through inhibition of tumor-associated NADH oxidase (tNOX), and diminished SIRT1 expression leading to enhanced p53 acetylation and apoptosis. Moreover, SIRT1 depletion by RNA interference attenuated capsaicin-induced apoptosis in A549 cancer cells and autophagy in MRC-5 cells, suggesting a vital role for SIRT1 in capsaicin-mediated cell death. Collectively, these data not only explain the differential cytotoxicity of capsaicin but shed light on the distinct cellular responses to capsaicin in cancerous and noncancerous cell lines.

Dual oxidase 2 is essential for house dust mite-induced pro-inflammatory cytokine production in human keratinocytes

House dust mites (HDMs) are known to trigger chronic inflammation through Toll-like receptors (TLRs) and their signalling cascades. In this study, we found that TLR2 ligation by HDMs induced the activation of dual oxidase 2 (Duox2) and nuclear factor-κB (NF-κB), leading to the production of pro-inflammatory cytokines in human keratinocytes. Stimulation of human keratinocytes with HDMs resulted in increases in interleukin-8 (IL-8) and chemokine (C-C motif) ligand 20 (CCL20) levels. However, pro-inflammatory cytokine production was abolished in keratinocytes transfected with TLR2 siRNA, indicating that HDM-induced cytokine production was mediated via TLR2 signalling. We also examined the function of Duox1/2 isozymes, which are primarily expressed in keratinocytes, in HDM-mediated pro-inflammatory cytokine production. Human keratinocytes transfected with control siRNA or Duox1 siRNA showed no inhibition of IL-8 or CCL20 production in response to HDMs, whereas the silencing of Duox2 expression resulted in a failure to induce cytokine production. Moreover, the phosphorylation and nuclear localization of RelA/p65, a component of NF-κB, were induced by HDMs in human keratinocytes. Transfection of human keratinocytes with TLR2 siRNA or Duox2 siRNA resulted in the complete abolishment of RelA/p65 nuclear localization in response to HDMs. Taken together, these results indicate that the HDM-dependent TLR2-Duox2 signalling axis indeed promotes NF-κB activation, which induces IL-8 and CCL20 production and mediates epidermal keratinocyte inflammation.

Selective killing of K-ras-transformed pancreatic cancer cells by targeting NAD(P)H oxidase

Introduction

Oncogenic activation of the K-ras gene occurs in >90% of pancreatic ductal carcinoma and plays a critical role in the pathogenesis of this malignancy. Increase of reactive oxygen species (ROS) has also been observed in a wide spectrum of cancers. This study aimed to investigate the mechanistic association between K-ras–induced transformation and increased ROS stress and its therapeutic implications in pancreatic cancer.

Methods

ROS level, NADPH oxidase (NOX) activity and expression, and cell invasion were examined in human pancreatic duct epithelial E6E7 cells transfected with K-ras^G12V compared with parental E6E7 cells. The cytotoxic effect and antitumor effect of capsaicin, a NOX inhibitor, were also tested in vitro and in vivo.

Results

K-ras transfection caused activation of the membrane-associated redox enzyme NOX and elevated ROS generation through the phosphatidylinositol 3′-kinase (PI3K) pathway. Importantly, capsaicin preferentially inhibited the enzyme activity of NOX and induced severe ROS accumulation in K-ras–transformed cells compared with parental E6E7 cells. Furthermore, capsaicin effectively inhibited cell proliferation, prevented invasiveness of K-ras–transformed pancreatic cancer cells, and caused minimum toxicity to parental E6E7 cells. In vivo, capsaicin exhibited antitumor activity against pancreatic cancer and showed oxidative damage to the xenograft tumor cells.

Conclusions

K-ras oncogenic signaling causes increased ROS stress through NOX, and abnormal ROS stress can selectively kill tumor cells by using NOX inhibitors. Our study provides a basis for developing a novel therapeutic strategy to effectively kill K-ras–transformed cells through a redox-mediated mechanism.

The impact of capsaicin intake on risk of developing gastric cancers: a meta-analysis

BACKGROUND

Reported associations of capsaicin with gastric cancer development have been conflicting. Here, we examine 10 published articles that explore these associations using 2,452 cases and 3,996 controls.

METHODS

We used multiple search strategies in MEDLINE through PubMed to seek for suitable articles that had case-control design with gastric cancer as outcome.

RESULTS

The outcomes of our study shows protection (odds ratio [OR] 0.55, P = 0.003) and susceptibility (OR 1.94, P = 0.0004), both significant with low and medium-high intake of capsaicin, respectively, although under relatively heterogeneous conditions (P(heterogeneity) = <0.0001). Outlier analysis resulted in loss of overall heterogeneity (P = 0.14) without affecting the pooled ORs. Among the subgroups, low intake elicited protection in both Korean (OR 0.37) and Mexican (OR 0.63) populations while high intake rendered these subgroups susceptible (OR 2.96 and OR 1.57, respectively). These subgroup values were highly significant (P = 0.0001-0.01) obtained in heterogeneous conditions (P(heterogeneity) < 0.0001-0.04). The homogeneous (P(heterogeneity) = 0.27-0.37) H. pylori (OR 0.60 and 1.69) effects were highly significant (P < 0.001) in the low and medium-high intake analyses, respectively. Given outcomes from the tests of interaction, high capsaicin intake is significantly different from the protection that low consumption offers.

CONCLUSIONS

This meta-analysis implies moderation in capsaicin consumption in order to derive its protective benefits.

Capsaicin inhibits the adipogenic differentiation of bone marrow mesenchymal stem cells by regulating cell proliferation, apoptosis, oxidative and nitrosative stress

Suppression of the maturation of pre-adipocytes into adipocytes and inhibition of the differentiation of mesenchymal stem cells into adipocytes by capsaicin.

Oxidant-based anticancer activity of a novel synthetic analogue of capsaicin, capsaicin epoxide

OBJECTIVES

Plant-derived natural substances, such as capsaicin, with potent antiproliferative activity against cancer cells in vitro are considered to be promising nutraceuticals in anticancer therapy. Nevertheless, the limited systemic bioavailability of phytochemicals may raise questions regarding the physiological relevance of their phytochemical effects in vivo. Thus, the search for novel phytochemical-based substances with more efficient anticancer action is needed.

METHODS

In the present study, a capsaicin analogue, namely, capsaicin epoxide, was synthesized, and its cytotoxic potential against cancer cells was evaluated and compared to that of capsaicin through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and multi-caspase assays. The abilities of capsaicin and capsaicin epoxide to induce oxidative stress were estimated using redox-sensitive fluorogenic probes: 2',7'-dichlorodihydrofluorescein diacetate (H2DCF-DA) and dihydroethidium.

RESULTS

The structure and purity of the synthesized product were confirmed by nuclear magnetic resonance spectroscopy, electrospray ionization mass spectrometry, and gas chromatography. Normal human dermal fibroblasts were not susceptible to treatment with the agent, whereas a cancer cell type-specific response was observed. Human breast carcinoma cells were found to be the most sensitive to capsaicin epoxide treatment compared with capsaicin treatment, and the action of capsaicin epoxide was oxidant based.

DISCUSSION

Our data indicate that the antiproliferative activity of capsaicin epoxide is potentiated in vitro, when used at much lower concentrations compared with capsaicin at similar concentrations. Thus, the findings of this study may have implications for phytochemical-based anticancer drug development.

Chemopreventive and Anticancer Activities of Allium victorialis var. platyphyllum Extracts

Background:

Allium victorialis var. platyphyllum is an edible perennial herb and has been used as a vegetable or as a Korean traditional medicine. Allium species have received much attention owing to their diverse pharmacological properties, including antioxidative, anti-inflammatory, and anticancer activities. However, A. victorialis var. platyphyllum needs more study.

Methods:

The chemopreventive potential of A. victorialis var. platyphyllum methanol extracts was examined by measuring 12-O-tetra-decanoylphorbol 13-acetate (TPA)-induced superoxide anion production in the differentiated HL-60 cells, TPA-induced mouse ear edema, and Ames/Salmonella mutagenicity. The apoptosis-inducing capabilities of the extracts were evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay, 4’,6-diamidino-2-phenylindole staining, and the DNA fragmentation assay in human colon cancer HT-29 cells. Antimetastatic activities of the extracts were also investigated in an experimental mouse lung metastasis model.

Results:

The methanol extracts of A. victorialis var. platyphyllum rhizome (AVP-R) and A. victorialis var. platyphyllum stem (AVP-S) dose-dependently inhibited the TPA-induced generation of superoxide anion in HL-60 cells and TPA-induced ear edema in mice, as well as 7,12-dimethylbenz[a]anthracene (DMBA) and tert-butyl hydroperoxide (t-BOOH) -induced bacterial mutagenesis. AVP-R and AVP-S reduced cell viability in a dose-related manner and induced apoptotic morphological changes and internucleosomal DNA fragmentation in HT-29 cells. In the experimental mouse lung metastasis model, the formation of tumor nodules in lung tissue was significantly inhibited by the treatment of the extracts.

Conclusions:

AVP-R and AVP-S possess antioxidative, anti-inflammatory, antimutagenic, proapoptotic, and antimetastatic activities. Therefore, these extracts can serve as a beneficial supplement for the prevention and treatment of cancer.

MicroRNA-520a-5p displays a therapeutic effect upon chronic myelogenous leukemia cells by targeting STAT3 and enhances the anticarcinogenic role of capsaicin

Aberrant expression profiles of microRNAs (miRNAs) have been previously demonstrated for having essential roles in a wide range of cancer types including leukemia. Antiproliferative or proapoptotic effects of capsaicin have been reported in several cancers. We aimed to study miRNAs involved in the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway in chronic myeloid leukemia cell model and the effects of the capsaicin treatment on cell proliferation and miRNA regulation. miR-520a-5p expression was extremely downregulated in capsaicin-treated cells. Repressing the level of miR-520a-5p by transient transfection with specific miRNA inhibitor oligonucleotides resulted in induced inhibition of proliferation in leukemic cells. According to bioinformatics analysis, STAT3 messenger RNA was predicted as a putative miR-520a-5p target; which was confirmed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and Western blot analysis. Cell proliferation inhibition was enhanced upon knockdown of STAT3 by RNA interference applications, but when miR-520a-5p inhibitor was additionally transfected onto STAT3 silenced cells, cell viability was dramatically decreased in leukemia cells. Finally, we observed the effects of capsaicin following miR-520a-5p inhibitor transfection upon cell proliferation, apoptosis, and STAT3 expression levels. We determined that, downregulation of miR-520a-5p affected the proliferation inhibition enhanced by capsaicin and reduced STAT3 mRNA and protein expression levels and increased apoptotic cell number. In summary, miR-520a-5p displays a therapeutic effect by targeting STAT3 and impacting the anticancer effects of capsaicin; whereas capsaicin, potentially through the miR-520a-5p/STAT3 interaction, induces apoptosis and inhibits K562 leukemic cell proliferation with need of further investigation.

Antineoplastic activity of rinvanil and phenylacetylrinvanil in leukaemia cell lines

In the search for novel chemotherapeutic agents for cancer treatment, capsaicin has been shown to inhibit proliferation and induce apoptosis in various types of cancer cell line, including leukaemia cell lines. The capsaicin analogues, rinvanil and phenylacetylrinvanil (PhAR), share a binding affinity for vanilloid receptors and may have biological activities similar to capsaicin; however, their anticancer potential has not yet been reported. This study analyses the antineoplastic activities of rinvanil and PhAR in leukaemia versus normal cells. P388, J774 and WEHI-3 leukaemia cell lines, as well as mouse bone marrow mononuclear cells, were cultured with varying concentrations of rinvanil and PhAR. Following this, proliferation and apoptosis were determined by the sulforhodamine B (SRB) assay and DNA ladder. Cultured leukaemia cell lines and mouse bone marrow mononuclear cells demonstrated a dose-dependent inhibition of proliferation, while non-diseased cells were less sensitive to the cytotoxic effect of capsaicin, rinvanil and PhAR. Rinvanil and PhAR also induced apoptosis in leukaemia cell lines but not in bone marrow. Given the lower IC₅₀ values for apoptosis induction in leukaemia cells compared with that of normal cells, PhAR is a promising selective anticancer agent.

Vanilloids induce oral cancer apoptosis independent of TRPV1

OBJECTIVE

To investigate the mechanisms of vanilloid cytotoxicity and anti-tumor effects in oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

Immunohistochemistry and qPCR analyses demonstrated expression of the TRP vanilloid type 1 (TRPV1) receptor in OSCC. Using cell proliferation assays, calcium imaging, and three mouse xenograft models, prototypical vanilloid agonist (capsaicin) and antagonist (capsazepine) were evaluated for cytotoxic and anti-tumor effects in OSCC.

RESULTS

OSCC cell lines treated with capsaicin displayed significantly reduced cell viability. Pre-treatment with capsazepine failed to reverse these effects. Moreover, capsazepine alone was significantly cytotoxic to tumor cells, suggesting the mechanism-of-action is independent of TRPV1 activation. This was further confirmed by calcium imaging indicating that TRPV1 channels are not functional in the cell lines tested. We then examined whether the observed vanilloid cytotoxicity was due to the generation of reactive oxygen species (ROS) and subsequent apoptosis. Induction of ROS was confirmed by flow cytometry and reversed by co-treatment with the antioxidant N-acetyl-cysteine (NAC). NAC also significantly reversed vanilloid cytotoxicity in cell proliferation assays. Dose-dependent induction of apoptosis with capsazepine treatment was demonstrated by FACS analyses and c-PARP expression in treated cells. Our in vivo xenograft studies showed that intra-tumoral injections of capsazepine exhibited high effectiveness in suppressing tumor growth with no identifiable toxicities.

CONCLUSIONS

These findings confirm TRPV1 channel expression in OSCC. However anti-tumor effects of vanilloids are independent of TRPV1 activation and are most likely due to ROS induction and subsequent apoptosis. Importantly, these studies demonstrate capsazepine is a potential therapeutic candidate for OSCC.

Cancer prevention trial of a synergistic mixture of green tea concentrate plus Capsicum (CAPSOL-T) in a random population of subjects ages 40-84

Background

Experts agree that one of the more promising strategies in cancer management is early detection coupled with early intervention. In this study, we evaluated an early cancer detection strategy of cancer presence based on serum levels of the cancer-specific transcript variants of ENOX2 in serum coupled with an ENOX2-targeted nutraceutical preparation of green tea concentrate plus Capsicum (Capsol-T®) as a strategy of Curative Prevention® involving early detection coupled with early intervention in early stage cancer when in its most susceptible and manageable stages.

Experimental design

One hundred ten (110) subjects were tested for cancer presence using the ONCOblot® Tissue of Origin 2-D gel/western blot protocol for detection of serum presence of transcript variants of the ENOX2 protein. Subjects testing positive for ENOX2 received 350 mg of Capsol-T® in capsule form every 4 h including during the night for periods of at least 3 to 6 months or longer after which they were again tested for ENOX2 presence using the ONCOblot® Tissue of Origin Cancer Test protocol.

Results

Of the 110 subjects, both male and female, ages 40 to 84, with no evidence of clinical symptoms of cancer, 40% were positive for ENOX2 presence in the ONCOblot® Tissue of Origin Cancer Test. After completion of 3 to 17 months of Capsol-T® use, 94% of subjects subsequently tested negative for ENOX2 presence.

Conclusions

Oral Capsol-T® is well tolerated and, for ENOX2 presence in serum in the absence of clinical cancer symptoms, is consistently effective in reducing the serum ENOX2 levels to below detectable limits.

The potential antitumor effects of capsaicin

Capsaicin, one of the major pungent ingredients found in red peppers, has been recently demonstrated to induce apoptosis in many types of malignant cell lines including colon adenocarcinoma, pancreatic cancer, hepatocellular carcinoma, prostate cancer, breast cancer, and many others. The mechanism whereby capsaicin induces apoptosis in cancer cells is not completely elucidated but involves intracellular calcium increase, reactive oxygen species generation, disruption of mitochondrial membrane transition potential, and activation of transcription factors such as NFkappaB and STATS. Recently, a role for the AMP-dependent kinase (AMPK) and autophagy pathways in capsaicin-triggered cell death has been proposed. In addition, capsaicin shows antitumor activity in vivo by reducing the growth of many tumors induced in mice. In this chapter, we report the last advances performed in the antitumor activity of capsaicin and review the main signaling pathways involved.

Omega-3 but not omega-6 unsaturated fatty acids inhibit the cancer-specific ENOX2 of the HeLa cell surface with no effect on the constitutive ENOX1

Epidemiological and laboratory studies suggest that dietary fatty acids (oleic acid (in olive oil), eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) (in fish oil)) play important roles in carcinogenesis. The most potent antitumor effects of all fatty acids are given by fatty acid conjugated linoleic acid (CLA). The antitumor effects of CLA may be mediated through enhanced apoptosis. While CLA, EPA, and DHA (omega-3 polyunsaturated fatty acids) have inhibitory effects on cancer cells, omega-6 fatty acids have often shown negative or potentiating effects on cancer cells. Linoleic acid (an omega-6) is desaturated in the cell by delta 6 and 5 destaturases to form arachidonic acid. COX 1 and 2 isoforms then act on arachidonic acid to form prostaglandins and other related regulatory molecules. It is normally thought that what is important to the development of the cancerous phenotype is some balance of these various metabolites. In experiments with surface NOX proteins released from HeLa cells, spectrophotometric measurements of the oxidation of NADH revealed inhibition of the cancer-specific ENOX2 activity by CLA and the omega-3 fatty acids, eicosapentaenoic, docosahexaenoic, and α-linolenic acids. The constitutive ENOX1 activity was not inhibited. In contrast, the omega-6 fatty acids, linoleic acid, and arachidonic acid inhibited neither ENOX1 nor ENOX2. The findings indicate the possibility that a direct effect of CLA and omega-3 fatty acids on ENOX2 may be responsible for the potent activity of CLA and omega-3 fatty acids in cancer prevention and therapy.

Chemotherapeutic agents enhance cell migration and epithelial-to-mesenchymal transition through transient up-regulation of tNOX (ENOX2) protein

BACKGROUND

Tumor-associated NADH oxidase (tNOX; ENOX2) is a growth-related protein expressed in transformed cells. High concentrations of numerous chemotherapeutic agents have shown to inhibit tNOX activity and protein levels leading to a reduction in cell growth while little is known for the effects of low concentrations of chemotherapeutic agents on tNOX expression.

METHODS

Effects of chemotherapeutic agents on cell function were evaluated with traditional in vitro assays and the xCELLigence System. Western blot analyses were used to study protein expression profiles of the epithelial-to-mesenchymal transition.

RESULTS

We showed that doxorubicin treatment transiently up-regulates tNOX expression in human lung carcinoma A549 cells in association with enhanced cell migration. Similar results were observed in tamoxifen-exposed A549 cells. Furthermore, protein marker analyses revealed that the enhanced migration induced by tamoxifen was correlated with epithelial-to-mesenchymal transition, as evidenced by down-regulation of epithelial markers and up-regulation of mesenchymal markers. Importantly, tNOX overexpression enhanced cell migration, confirming the essential role of tNOX in cell migration.

CONCLUSIONS

Based on these findings, we conclude that doxorubicin and tamoxifen induce a transient up-regulation of tNOX expression, leading to enhanced cell migration and EMT.

GENERAL SIGNIFICANCE

These findings establish an essential role for tNOX in cell migration and survival and may provide a rational framework for the further development of tNOX inhibitors as a novel class of antitumor agents.

Capsaicin-induced apoptosis of FaDu human pharyngeal squamous carcinoma cells

PURPOSE

To investigate the anti-tumor effect of capsaicin on human pharyngeal squamous carcinoma cells (FaDu).

MATERIALS AND METHODS

The 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.

RESULTS

Capsaicin 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.

CONCLUSION

Our 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.

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.

Capsaicin-mediated tNOX (ENOX2) up-regulation enhances cell proliferation and migration in vitro and in vivo

Cancer chemoprevention is employed to block or reverse the progression of malignancies. To date, several thousands of agents have been found to possess chemopreventative activity, one of which is capsaicin, a component of chili peppers that exhibits antigrowth activity against various cancer cell lines. However, the role of capsaicin in tumorigenesis remains controversial because both cancer prevention and promotion have been proposed. Here, we made the unexpected discovery that treatment with low concentrations of capsaicin up-regulates tNOX (tumor-associated NADH oxidase) expression in HCT116 human colon carcinoma cells in association with enhanced cell proliferation and migration, as evidenced by down-regulation of epithelial markers and up-regulation of mesenchymal markers. Importantly, tNOX-knockdown in HCT116 cells by RNA interference reversed capsaicin-induced cell proliferation and migration in vitro and decreased tumor growth in vivo. Collectively, these findings provide a basis for explaining the tumor-promoting effect of capsaicin and might imply that caution should be taken when using capsaicin as a chemopreventive agent.

Down-regulation of tumor-associated NADH oxidase, tNOX (ENOX2), enhances capsaicin-induced inhibition of gastric cancer cell growth

Gastric cancer is a common human malignancy and a major contributor to cancer-related deaths worldwide. Unfortunately, the prognosis of most gastric cancer patients is poor because they are generally diagnosed at a late stage after the cancer has already metastasized. Most current research, therefore, emphasizes selective targeting of cancer cells by apoptosis-inducing agents. One such therapeutic agent is capsaicin, a component of chili peppers that has been shown to possess anti-growth activity against various cancer cell lines. Here, we examined the effect of capsaicin on SNU-1 and TMC-1 gastric cancer cells and found differing outcomes between the two cell lines. Our results show that capsaicin induced significant cytotoxicity with increases in oxidative stress, PARP cleavage, and apoptosis in sensitive SNU-1 cells. In contrast, TMC-1 cells were much less sensitive to capsaicin, exhibiting low cytotoxicity and very little apoptosis in response to capsaicin treatment. Capsaicin-induced apoptosis in SNU-1 cells was associated with down-regulation of tumor-associated NADH oxidase (tNOX) mRNA and protein. On the contrary, tNOX expression was scarcely affected by capsaicin in TMC-1 cells. We further showed that tNOX-knockdown sensitized TMC-1 cells to capsaicin-induced apoptosis and G1 phase accumulation, and led to decreased cell growth, demonstrating that tNOX is essential for cancer cell growth. Collectively, these results indicate that capsaicin induces divergent effects of the growth of gastric cancer cells that parallel its effects on tNOX expression, and demonstrate that forced tNOX down-regulation restored capsaicin-induced growth inhibition in TMC-1 cells.

Suppression of tumor necrosis factor-α-induced nuclear factor κB activation and aromatase activity by capsaicin and its analog capsazepine

Target-specific drugs, including natural products, offer promise for the amelioration of cancer and other human ailments. Capsaicin, the pungent ingredient present in chilies (Capsicum annuum L.), and capsazepine, a synthetic analog of capsaicin (collectively referred to as vanilloids), are known to possess a variety of pharmacological and physiological properties. In our continuous effort to discover and characterize cancer chemopreventive agents from natural products, we investigated the effect of vanilloids on nuclear factor κ-light-chain-enhancer of activated B cells (NFκB) activation using stably transfected 293/NFκB-Luc human embryonic kidney cells induced by treatment with tumor necrosis factor-α (TNFα) and on aromatase activity. Capsaicin and capsazepine blocked TNFα-induced NFκB activation in a dose-dependent manner with 50% inhibitory concentration (IC(50)) values of 0.68 and 4.2 μM, respectively. No significant cytotoxicity was observed at the highest concentrations tested (53.1 μM for capsazepine and 65.5 μM for capsaicin). In addition, these vanilloids inhibited aromatase activity with IC(50) values of 13.6 and 8.8 μM, respectively. Computer-aided molecular docking studies showed docking scores indicative of good binding affinity of vanilloids with aromatase and NFκB. The highly conserved residues for capsaicin and capsazepine binding with NFκB p50 were Ser299 and Ile278 (H-bond 2.81Å) and with NFκB p100 were Ser6, Arg82, Val86, Arg90 (H-bond 2.89Å), Gly4, and Ser2 (H-bond 2.81Å). The amino acids Trp224, Arg435, and Val373 (H-bond 2.80Å) were found to be important for the binding of capsaicin and capsazepine with aromatase. Based on these findings, aromatase and NFκB are suggested as valid targets for these compounds; additional investigation of chemopreventive or chemotherapeutic potential is required.