Capsaicin-induced genotoxic stress does not promote apoptosis in A549 human lung and DU145 prostate cancer cells

Recent Research Advances in Double-Strand Break and Mismatch Repair Defects in Prostate Cancer and Potential Clinical Applications

Prostate cancer remains a leading cause of cancer-related death in men worldwide. Recent research advances have emphasized the critical roles of mismatch repair (MMR) and double-strand break (DSB) in prostate cancer development and progression. Here, we provide a comprehensive review of the molecular mechanisms underlying DSB and MMR defects in prostate cancer, as well as their clinical implications. Furthermore, we discuss the promising therapeutic potential of immune checkpoint inhibitors and PARP inhibitors in targeting these defects, particularly in the context of personalized medicine and further perspectives. Recent clinical trials have demonstrated the efficacy of these novel treatments, including Food and Drugs Association (FDA) drug approvals, offering hope for improved patient outcomes. Overall, this review emphasizes the importance of understanding the interplay between MMR and DSB defects in prostate cancer to develop innovative and effective therapeutic strategies for patients.

Cytotoxicity of capsaicin and its analogs in vitro

Abstract Capsaicin (CAP) is the main compound responsible for the spicy flavor of Capsicum plants. However, its application can be inhibited due to its pungency and toxicity. This study aimed to evaluate and compare the cytotoxic effect of CAP and its analogs N-benzylbutanamide (AN1), N-(3-methoxybenzyl) butanamide (AN2), N-(4-hydroxy-3-methoxybenzyl) butanamide (AN3), N-(4-hydroxy-3-methoxybenzyl) hexanamide (AN4) and N-(4-hydroxy-3-methoxybenzyl) tetradecanamide (AN5) on the hepatoma cells of Rattus norvegicus using the MTT test. The results showed cytotoxicity of CAP at concentrations of 100, 150, 175, and 200 μM (24 hours), AN1 at 150 and 175 μM (48 hours), AN2 at 50 μM (24 hours) and 10, 25, 50, and 75 μM (48 hours), AN4 at 175 μM (24 hours), and AN5 at 50 μM (48 hours). Removing the hydroxyl radical from the vanillyl group of capsaicin, together with reducing the acyl chain to 3 carbons, which is the case of AN2, resulted in the best biological activity. Increasing the carbon chain in the acyl group of the capsaicin molecule, which is the case of AN5, also showed evident cytotoxic effects. The present study proves that the chemical modifications of capsaicin changed its biological activity.

Capsaicin Potentiates Anticancer Drug Efficacy Through Autophagy-Mediated Ribophorin II Downregulation and Necroptosis in Oral Squamous Cell Carcinoma Cells

The ability of capsaicin co-treatment to sensitize cancer cells to anticancer drugs has been widely documented, but the detailed underlying mechanisms remain unknown. In addition, the role of ribophorin II turnover on chemosensitization is still uncertain. Here, we investigated capsaicin-induced sensitization to chemotherapeutic agents in the human oral squamous carcinoma cell lines, HSC-3 and SAS. We found that capsaicin (200 μM) did not induce remarkable apoptotic cell death in these cell lines; instead, it significantly enhanced autophagy with a concomitant decrease of ribophorin II protein. This capsaicin-induced decrease in ribophorin II was intensified by the autophagy inducer, rapamycin, but attenuated by the autophagy inhibitors, ULK1 inhibitor and chloroquine, indicating that the autophagic process was responsible for the capsaicin-induced down-regulation of ribophorin II. Co-administration of capsaicin with conventional anticancer agents did, indeed, sensitize the cancer cells to these agents. In co-treated cells, the induction of apoptosis was significantly reduced and the levels of the necroptosis markers, phospho-MLKL and phospho-RIP3, were increased relative to the levels seen in capsaicin treatment alone. The levels of DNA damage response markers were also diminished by co-treatment. Collectively, our results reveal a novel mechanism by which capsaicin sensitizes oral cancer cells to anticancer drugs through the up-regulation of autophagy and down-regulation of ribophorin II, and further indicate that the induction of necroptosis is a critical factor in the capsaicin-mediated chemosensitization of oral squamous carcinoma cells to conventional anticancer drugs.

Proteomic Analysis of Hypoxia-Induced Senescence of Human Bone Marrow Mesenchymal Stem Cells

Methods

Hypoxia in hBMSCs was induced for 0, 4, and 12 hours, and cellular senescence was evaluated by senescence-associated β-galactosidase (SA-β-gal) staining. Tandem mass tag (TMT) labeling was combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for differential proteomic analysis of hypoxia in hBMSCs. Parallel reaction monitoring (PRM) analysis was used to validate the candidate proteins. Verifications of signaling pathways were evaluated by western blotting. Cell apoptosis was evaluated using Annexin V/7-AAD staining by flow cytometry. The production of reactive oxygen species (ROS) was detected by the fluorescent probe 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA).

Results

Cell senescence detected by SA-β-gal activity was higher in the 12-hour hypoxia-induced group. TMT analysis of 12-hour hypoxia-induced cells identified over 6000 proteins, including 686 differentially expressed proteins. Based on biological pathway analysis, we found that the senescence-associated proteins were predominantly enriched in the cancer pathways, PI3K-Akt pathway, and cellular senescence signaling pathways. CDK1, CDK2, and CCND1 were important nodes in PPI analyses. Moreover, the CCND1, UQCRH, and COX7C expressions were verified by PRM. Hypoxia induction for 12 hours in hBMSCs reduced CCND1 expression but promoted ROS production and cell apoptosis. Such effects were markedly reduced by the PI3K agonist, 740 Y-P, and attenuated by LY294002.

Conclusions

Hypoxia of hBMSCs inhibited CCND1 expression but promoted ROS production and cell apoptosis through activating the PI3K-dependent signaling pathway. These findings provided a detailed characterization of the proteomic profiles related to hypoxia-induced senescence of hBMSCs and facilitated our understanding of the molecular mechanisms leading to stem cell senescence.

Remifentanil preconditioning protects against hypoxia-induced senescence and necroptosis in human cardiac myocytes in vitro

Remifentanil and other opioids are suggested to be protective against ischemia-reperfusion injury in animal models and coronary artery bypass surgery patients, however the molecular basis of such protection is far from being understood. In the present study, we have used a model of human cardiomyocytes treated with the hypoxia-mimetic agent cobalt chloride to investigate remifentanil preconditioning-based adaptive responses and underlying mechanisms. Hypoxic conditions promoted oxidative and nitrosative stress, p21-mediated cellular senescence and the activation of necroptotic pathway that was accompanied by a 2.2-, 9.6- and 8.2-fold increase in phosphorylation status of mixed lineage kinase domain-like pseudokinase (MLKL) and release of pro-inflammatory cytokine IL-8 and cardiac troponin I, a marker of myocardial damage, respectively. Remifentanil preconditioning was able to lower hypoxia-mediated protein carbonylation and limit MLKL-based signaling and pro-inflammatory response to almost normoxic control levels, and decrease hypoxia-induced pro-senescent activity of about 21% compared to control hypoxic conditions. In summary, we have shown for the first time that remifentanil can protect human cardiomyocytes against hypoxia-induced cellular senescence and necroptosis that may have importance with respect to the use of remifentanil to diminish myocardial ischemia and reperfusion injury in patients undergoing cardiac surgery.

Energy Conversion and Biocompatibility of Surface Functionalized Magnetite Nanoparticles with Phosphonic Moieties

Magnetite nanoparticles (MNPs) were synthesized using two distinctly different approaches, co-precipitation (CP) and thermal decomposition (TD), and further surface functionalized with organophosphonic ligands containing different numbers of phosphonic groups. We have shown that it is possible to fabricate flower-like assemblies of MNPs through TD at lower temperatures, whereas CP MNPs formed agglomerates of particles with broad size distribution and irregular shapes. The effect of the organophosphonic ligands on the heating efficiency of the TD and CP MNPs under dual mode stimulation (simultaneous action of AMF and NIR laser radiation) was studied for the first time. It was found that in the case of the cost-effective CP MNP synthesis surface functionalization with chosen phosphonic ligands leads to higher heating efficiency upon laser stimulation, whereas better performance of TD MNPs was found under the action of AMF due to the significant difference of nanoparticle properties. The biocompatibility of surface functionalized MNPs with organophosphonic ligands was evaluated through thorough studies of the metabolic activity of MNPs in normal human foreskin fibroblasts as well as oxidative stress induction and oxidation stress response which has not been previously reported for most of the organophosphonic moieties used in this study.

AMPK-mediated senolytic and senostatic activity of quercetin surface functionalized Fe3O4 nanoparticles during oxidant-induced senescence in human fibroblasts

Cellular senescence may contribute to aging and age-related diseases and senolytic drugs that selectively kill senescent cells may delay aging and promote healthspan. More recently, several categories of senolytics have been established, namely HSP90 inhibitors, Bcl-2 family inhibitors and natural compounds such as quercetin and fisetin. However, senolytic and senostatic potential of nanoparticles and surface-modified nanoparticles has never been addressed. In the present study, quercetin surface functionalized Fe₃O₄ nanoparticles (MNPQ) were synthesized and their senolytic and senostatic activity was evaluated during oxidative stress-induced senescence in human fibroblasts in vitro. MNPQ promoted AMPK activity that was accompanied by non-apoptotic cell death and decreased number of stress-induced senescent cells (senolytic action) and the suppression of senescence-associated proinflammatory response (decreased levels of secreted IL-8 and IFN-β, senostatic action). In summary, we have shown for the first time that MNPQ may be considered as promising candidates for senolytic- and senostatic-based anti-aging therapies.

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Quercetin surface functionalized magnetite nanoparticles (MNPQ) were synthesized.

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MNPQ eliminated hydrogen peroxide-induced senescent human fibroblasts.

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MNPQ limited senescence-associated proinflammatory responses.

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Senotherapeutic action of MNPQ was accompanied by increased activity of AMPK.

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MNPQ may be useful for senolytic- and senostatic-based anti-aging therapies.

In vitro exposure to thiacloprid-based insecticide formulation promotes oxidative stress, apoptosis and genetic instability in bovine lymphocytes

A proprietary thiacloprid-based neonicotinoid insecticide formulation is widely used in agriculture to protect vegetables and fruit against various pests. However, its effect on animal cells has not been fully elucidated. In this study, bovine peripheral lymphocytes were incubated with different concentrations of this formulation (10; 30; 60; 120 and 240 μg.mL^-1) for 4 h to address the potential cytotoxic and genotoxic effects of the insecticide. Insecticide formulation treatment resulted in decreased cell viability and proliferation, p53-mediated cell cycle arrest at the G₀/G₁ phase, and apoptosis induction accompanied by elevated levels of mitochondrial superoxide and protein carbonylation. Oxidant-based DNA damage and DNA damage response (DDR) were also observed, namely the formation of micronuclei, DNA double-strand breaks and slightly elevated recruitment of p53 binding protein (53BP1) foci. Our results contribute to the elucidation of insecticide effects on animal lymphocyte cultures after short-term exposure. Due to increased application of neonicotinoids worldwide, resulting in both higher yields and adverse effects on non-target animals and humans, further in vivo and in vitro experiments should be performed to confirm their cytotoxic and genotoxic activities during short-term exposure.

Capsaicinoids enhance chemosensitivity to chemotherapeutic drugs

Cytotoxic chemotherapy is the mainstay of cancer treatment. Conventional chemotherapeutic agents do not distinguish between normal and neoplastic cells. This leads to severe toxic side effects, which may necessitate the discontinuation of treatment in some patients. Recent research has identified key molecular events in the initiation and progression of cancer, promoting the design of targeted therapies to selectively kill tumor cells while sparing normal cells. Although, the side effects of such drugs are typically milder than conventional chemotherapies, some off-target effects still occur. Another serious challenge with all chemotherapies is the acquisition of chemoresistance upon prolonged exposure to the drug. Therefore, identifying supplementary agents that sensitize tumor cells to chemotherapy-induced apoptosis and help minimize drug resistance would be valuable for improving patient tolerance and response to chemotherapy. The use of effective supplementary agents provides a twofold advantage in combination with standard chemotherapy. First, by augmenting the activity of the chemotherapeutic drug it can lower the dose needed to kill tumor cells and decrease the incidence and severity of treatment-limiting side effects. Second, adjuvant therapies that lower the effective dose of chemotherapy may delay/prevent the development of chemoresistance in tumors. Capsaicinoids, a major class of phytochemical compounds isolated from chili peppers, have been shown to improve the efficacy of several anti-cancer drugs in cell culture and animal models. The present chapter summarizes the current knowledge about the chemosensitizing activity of capsaicinoids with conventional and targeted chemotherapeutic drugs, highlighting the potential use of capsaicinoids in novel combination therapies to improve the therapeutic indices of conventional and targeted chemotherapeutic drugs in human cancers.

Synthesis and characterization of a polyurethane carrier used for a prolonged transmembrane transfer of a chili pepper extract

Purpose

Red chili peppers have been highly valued in gastronomy and traditional medicine since ancient times; it seems that it is not just an ingredient for food but also a good remedy for various medical conditions such as increased blood pressure and high levels of serum triglycerides and cholesterol, myocardial infarction, arthritis, and migraines. The objective of this study is the characterization of a new carrier used for encapsulated extract.

Methods

Chili pepper extract was obtained and was physically entrapped inside polyurethane microparticles in order to diminish the irritative potential of this extract. The particles were evaluated by Zetasizer measurements, small-angle neutron scattering and thermal analysis, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy; the encapsulation efficacy and the drug release profile were assessed by UV-Vis spectroscopy. Bioevaluations on mice skin were performed to predict the irritative potential of the samples.

Results

Two different types of samples were compared: hollow polyurethane microparticles vs polyurethane particles containing the natural extract. The sizes of the particles were very similar, but the sample containing the extract presents three particle populations (the polydispersity index increases from 0.3 to 0.6 from one sample to another). The zeta-potential measurements and SEM images indicate a medium tendency to form clusters, while the UV-Vis study revealed an almost 70% encapsulation efficacy.

Conclusion

The results suggest that encapsulation of a chili pepper extract inside polyurethane microparticles leads to a non-irritative product with a prolonged release: ~30% of encapsulated extract is released within the first 8 days and a maximum 45% is reached in 2 weeks.

Snake venoms promote stress-induced senescence in human fibroblasts

Snake venoms are widely studied in terms of their systemic toxicity and proteolytic, hemotoxic, neurotoxic, and cytotoxic activities. However, little is known about snake-venom-mediated effects when used at low, noncytotoxic concentrations. In the current study, two human fibroblast cell lines of different origin, namely WI-38 fetal lung fibroblasts and BJ foreskin fibroblasts were used to investigate snake-venom-induced adaptive response at a relatively noncytotoxic concentration (0.01 µg/ml). The venoms of Indochinese spitting cobra ( Naja siamensis), western green mamba ( Dendroaspis viridis), forest cobra ( Naja melanoleuca), and southern copperhead ( Agkistrodon contortrix) were considered. Snake venoms promoted FOXO3a-mediated oxidative stress response and to a lesser extent DNA damage response, which lead to changes in cell cycle regulators both at messenger RNA and protein levels, limited cell proliferation and migration, and induced cellular senescence. Taken together, we have shown for the first time that selected snake venoms may also exert adverse effects when used at relatively noncytotoxic concentrations.

Development of self-repair nano-rod scaffold materials for implantation of osteosarcoma affected bone tissue

Nano-hydroxyapatite with a xylitol based co-polymer and a capsaicin loaded scaffold was investigated as a natural antioxidant loaded bone implant material on osteosarcoma cells.

Downregulation of methyltransferase Dnmt2 results in condition-dependent telomere shortening and senescence or apoptosis in mouse fibroblasts

Dnmt2 is a highly conserved methyltransferase of uncertain biological function(s). As Dnmt2 was considered as a driver of fruit fly longevity and a modulator of stress response, we decided to evaluate the role of Dnmt2 during stress-induced premature senescence in NIH3T3 mouse fibroblasts. Stable knockdown of Dnmt2 resulted in hydrogen peroxide-mediated sensitivity and apoptosis, whereas in the control conditions, senescence was induced. Cellular senescence was accompanied by elevated levels of p53 and p21, decreased telomere length and telomerase activity, increased production of reactive oxygen species and protein carbonylation, and DNA damage. Dnmt2 silencing also promoted global DNA and RNA hypermethylation, and upregulation of methyltransferases, namely Dnmt1, Dnmt3a, and Dnmt3b. Taken together, we show for the first time that Dnmt2 may promote lifespan in the control conditions and survival during stress conditions in mouse fibroblasts.

Electrochemical detection of interaction between capsaicin and nucleic acids in comparison to agarose gel electrophoresis

In this study, the biomolecular interaction occurred between nucleic acids and Capsaicin (CPS), the active compound in chilli peppers, which has been reported to have anti-carcinogenic properties, was investigated for the first time herein using disposable electrochemical biosensor. It is aimed to perform the surface-confined interaction between CPS and different types of nucleic acids and under this aim, the experimental conditions were optimized; such as, the concentration of CPS and DNA, DNA immobilization time and interaction time etc. The detection limit of DNA was estimated based on guanine oxidation signal in the linear concentration range of DNA from 1 to 5 μg/mL, and it was found to be 0.62 μg/mL. The effect of time-dependent manner from 1 min to 30 min on the interaction of CPS with nucleic acids was explored upon to the changes at guanine signal coming from double stranded DNA and cDNA as well as PCR samples. The interaction of CPS with double stranded DNA was also determined by agarose gel electrophoresis.

Capsaicin inhibits proliferation and induces apoptosis in osteosarcoma cell lines via the mitogen‑activated protein kinase pathway

Capsaicin, a pungent molecular compound present in many hot peppers, exerts anticancer activities against various human cancer cell lines by inducing apoptosis. However, the effects of capsaicin on human osteosarcoma (OS) as well as the related mechanisms remain to be fully elucidated. In the present study, the anticancer effects of capsaicin on 3 human OS cell lines (MG63, 143B and HOS) were investigated. Various concentrations of capsaicin (50-300 µM) effectively decreased cell viability in all 3 OS cell lines in a dose-dependent manner. Notably, capsaicin-induced apoptosis was observed when OS cells were treated with relatively high concentrations of capsaicin (starting at 250 µM). In addition, the mitochondrial apoptotic pathway was involved in the capsaicin-induced apoptosis in the OS cells. Meanwhile, our results also indicated that at relatively low concentrations (e.g., 100 µM), capsaicin could inhibit the proliferation, decrease the colony forming ability and induce G0/G1 phase cell cycle arrest of OS cells in a dose-dependent manner. Moreover, our results revealed that the anticancer effects induced by capsaicin on OS cell lines involved multiple MAPK signaling pathways as indicated by inactivation of the ERK1/2 and p38 pathways and activation of the JNK pathway. Furthermore, the results of animal experiments showed that capsaicin inhibited tumor growth in a xenograft model of human OS. In conclusion, these results indicate that capsaicin may exert therapeutic benefits as an adjunct to current cancer therapies but not as an independent anticancer agent.

Reduced levels of methyltransferase DNMT2 sensitize human fibroblasts to oxidative stress and DNA damage that is accompanied by changes in proliferation-related miRNA expression

Methyltransferase DNMT2 is suggested to be involved in the regulation of numerous processes, however its biological significance and underlying molecular mechanisms remain elusive. In the present study, we have used WI-38 and BJ human fibroblasts as an in vitro model system to investigate the effects of siRNA-based DNMT2 silencing. DNMT2-depleted cells were found to be sensitive to oxidative stress conditions as judged by increased production of reactive oxygen species and susceptible to DNA damage that resulted in the inhibition of cell proliferation. DNMT2 silencing promoted upregulation of proliferation-related and tumor suppressor miRNAs, namely miR-28-3p, miR-34a-3p, miR-30b-5p, miR-29b-3p, miR-200c-3p, miR-28-5p, miR-379-5p, miR-382-5p, miR-194-5p, miR-193b-3p and miR-409-3p. Moreover, DNMT2 silencing induced cellular senescence and DNMT2 levels were elevated in replicatively senescent cells. Taken together, we found that DNMT2 may take part in the regulation of cell proliferation and longevity in human fibroblasts and speculate that the manipulation of DNMT2 levels that limits cell proliferation may be potentially useful anticancer strategy.

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DNMT2 silencing promotes oxidative stress and DNA damage in human fibroblasts.

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DNMT2 silencing results in upregulation of proliferation-related miRNAs.

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DNMT2 silencing inhibits cell proliferation and induces cellular senescence.

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DNMT2 levels are elevated during replicative senescence.

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DNMT2 is a novel regulator of cell proliferation and longevity in human fibroblasts.

Sulforaphane-Induced Cell Cycle Arrest and Senescence are accompanied by DNA Hypomethylation and Changes in microRNA Profile in Breast Cancer Cells

Cancer cells are characterized by genetic and epigenetic alterations and phytochemicals, epigenetic modulators, are considered as promising candidates for epigenetic therapy of cancer. In the present study, we have investigated cancer cell fates upon stimulation of breast cancer cells (MCF-7, MDA-MB-231, SK-BR-3) with low doses of sulforaphane (SFN), an isothiocyanate. SFN (5-10 µM) promoted cell cycle arrest, elevation in the levels of p21 and p27 and cellular senescence, whereas at the concentration of 20 µM, apoptosis was induced. The effects were accompanied by nitro-oxidative stress, genotoxicity and diminished AKT signaling. Moreover, SFN stimulated energy stress as judged by decreased pools of ATP and AMPK activation, and autophagy induction. Anticancer effects of SFN were mediated by global DNA hypomethylation, decreased levels of DNA methyltransferases (DNMT1, DNMT3B) and diminished pools of N6-methyladenosine (m6A) RNA methylation. SFN (10 µM) also affected microRNA profiles, namely SFN caused upregulation of sixty microRNAs and downregulation of thirty two microRNAs, and SFN promoted statistically significant decrease in the levels of miR-23b, miR-92b, miR-381 and miR-382 in three breast cancer cells. Taken together, we show for the first time that SFN is an epigenetic modulator in breast cancer cells that results in cell cycle arrest and senescence, and SFN may be considered to be used in epigenome-focused anticancer therapy.

Phytochemical-induced nucleolar stress results in the inhibition of breast cancer cell proliferation

The nucleolus is a stress sensor and compromised nucleolar activity may be considered as an attractive anticancer strategy. In the present study, the effects of three plant-derived natural compounds, i.e., sulforaphane (SFN), ursolic acid (UA) and betulinic acid (BA) on nucleolar state were investigated in breast cancer cell lines of different receptor status, namely MCF-7, MDA-MB-231 and SK-BR-3 cells. Cytostatic action of phytochemicals against breast cancer cells was observed at low micromolar concentration window (5-20µM) and mediated by elevated p21 levels, and cell proliferation of SFN-, UA- and BA-treated normal human mammary epithelial cells (HMEC) was unaffected. Phytochemical-mediated inhibition of cell proliferation was accompanied by increased levels of superoxide and protein carbonylation that lead to disorganization of A- and B-type lamin networks and alterations in the nuclear architecture. Phytochemicals promoted nucleolar stress as judged by the nucleoplasmic translocation of RNA polymerase I-specific transcription initiation factor RRN3/TIF-IA, inhibition of new rRNA synthesis and decrease in number of nucleoli. Phytochemicals also decreased the levels of NOP2, proliferation-associated nucleolar protein p120, and WDR12 required for maturation of 28S and 5.8S ribosomal RNAs and formation of the 60S ribosome, and phosphorylation of S6 ribosomal protein that may result in diminished translation and inhibition of cell proliferation. In summary, three novel ribotoxic stress stimuli were revealed with a potential to be used in nucleolus-focused anticancer therapy.

Capsaicin Induces Autophagy and Apoptosis in Human Nasopharyngeal Carcinoma Cells by Downregulating the PI3K/AKT/mTOR Pathway

Capsaicin is a potential chemotherapeutic agent for different human cancers. In Southeast China, nasopharyngeal carcinoma (NPC) has the highest incidence of all cancers, but final treatment outcomes are unsatisfactory. However, there is a lack of information regarding the anticancer activity of capsaicin in NPC cells, and its effects on the signaling transduction pathways related to apoptosis and autophagy remain unclear. In the present study, the precise mechanisms by which capsaicin exerts anti-proliferative effects, cell cycle arrest, autophagy and apoptosis were investigated in NPC-TW01 cells. Exposure to capsaicin inhibited cancer cell growth and increased G1 phase cell cycle arrest. Western blotting and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) were used to measure capsaicin-induced autophagy via involvement of the class III PI3K/Beclin-1/Bcl-2 signaling pathway. Capsaicin induced autophagy by increasing levels of the autophagy markers LC3-II and Atg5, enhancing p62 and Fap-1 degradation and increasing caspase-3 activity to induce apoptosis, suggesting a correlation of blocking the PI3K/Akt/mTOR pathway with the above-mentioned anticancer activities. Taken together, these data confirm that capsaicin inhibited the growth of human NPC cells and induced autophagy, supporting its potential as a therapeutic agent for cancer.

Ursolic acid-mediated changes in glycolytic pathway promote cytotoxic autophagy and apoptosis in phenotypically different breast cancer cells

Plant-derived pentacyclic triterpenotids with multiple biological activities are considered as promising candidates for cancer therapy and prevention. However, their mechanisms of action are not fully understood. In the present study, we have analyzed the effects of low dose treatment (5-20 µM) of ursolic acid (UA) and betulinic acid (BA) on breast cancer cells of different receptor status, namely MCF-7 (ER+, PR+/-, HER2-), MDA-MB-231 (ER-, PR-, HER2-) and SK-BR-3 (ER-, PR-, HER2+). UA-mediated response was more potent than BA-mediated response. Triterpenotids (5-10 µM) caused G0/G1 cell cycle arrest, an increase in p21 levels and SA-beta-galactosidase staining that was accompanied by oxidative stress and DNA damage. UA (20 µM) also diminished AKT signaling that affected glycolysis as judged by decreased levels of HK2, PKM2, ATP and lactate. UA-induced energy stress activated AMPK that resulted in cytotoxic autophagy and apoptosis. UA-mediated elevation in nitric oxide levels and ATM activation may also account for AMPK activation-mediated cytotoxic response. Moreover, UA-promoted apoptosis was associated with decreased pERK1/2 signals and the depolarization of mitochondrial membrane potential. Taken together, we have shown for the first time that UA at low micromolar range may promote its anticancer action by targeting glycolysis in phenotypically distinct breast cancer cells.

Diosmin-induced senescence, apoptosis and autophagy in breast cancer cells of different p53 status and ERK activity

Relatively low bioavailability of plant-derived nutraceuticals with anticancer properties may limit their usefulness for prevention and therapy of cancer. In the present study, we have screened for nutraceuticals (n=30) that would act at low micromolar range against phenotypically distinct breast cancer cell lines, namely MCF-7 (ER⁺, PR^+/-, HER2^-), MDA-MB-231 (ER^-, PR^-, HER2^-) and SK-BR-3 (ER^-, PR^-, HER2⁺), and diosmin, a citrus fruit flavonoid belonging to a flavone subclass, was selected. MCF-7 cell line was found to be the most sensitive to diosmin treatment. Diosmin caused G2/M cell cycle arrest, elevation in p53, p21 and p27 levels and stress-induced premature senescence when used at lower concentrations (5 and 10μM). Diosmin (20μM) also promoted apoptosis that was not observed in normal human mammary epithelial cells (HMEC). Diosmin stimulated oxidative and nitrosative stress, DNA damage and changes in global DNA methylation patterns. The status of p53 (wild type versus mutant) and the levels of phosphorylated ERK1/2 in a steady state, and diosmin-induced autophagy may reflect diverse response to diosmin treatment in MCF-7, MDA-MB-231 and SK-BR-3 cells, which in turn results in different cell fates. Taken together, diosmin that acts at low micromolar range against breast cancer cells may be considered as a promising candidate for anticancer therapy.

Capsaicin and dihydrocapsaicin induce apoptosis in human glioma cells via ROS and Ca2+‑mediated mitochondrial pathway

Human glioma is the most common type of primary brain tumor and one of the most invasive and aggressive tumors, which, even with treatments including surgery, radiotherapy and chemotherapy, often relapses and exhibits resistance to conventional treatment methods. Developing novel strategies to control human glioma is, therefore, an important research focus. The present study investigated the mechanism of apoptosis induction in U251 human glioma cells by capsaicin (Cap) and dihydrocapsaicin (DHC), the major pungent ingredients of red chili pepper, using the Cell Counting Kit‑8 assay, transmission electron microscopy analysis, flow cytometry analysis, laser scanning confocal microscope analysis and immunohistochemical staining. Treatment of U251 glioma cells with Cap and DHC resulted in a dose‑ and time‑dependent inhibition of cell viability and induction of apoptosis, whereas few effects were observed on the viability of L929 normal murine fibroblast cells. The apoptosis‑inducing effects of Cap and DHC in U251 cells were associated with the generation of reactive oxygen species, increased Ca2+ concentrations, mitochondrial depolarization, release of cytochrome c into the cytosol and activation of caspase‑9 and ‑3. These effects were further confirmed by observations of the anti‑tumor effects of Cap and DHC in vivo in a U251 cell murine tumor xenograft model. These results demonstrate that Cap and DHC are effective inhibitors of in vitro and in vivo survival of human glioma cells, and provide the rationale for further clinical investigation of Cap and DHC as treatments for human glioma.

Capsaicin Suppresses Cell Proliferation, Induces Cell Cycle Arrest and ROS Production in Bladder Cancer Cells through FOXO3a-Mediated Pathways

Capsaicin (CAP), a highly selective agonist for transient receptor potential vanilloid type 1 (TRPV1), has been widely reported to exhibit anti-oxidant, anti-inflammation and anticancer activities. Currently, several therapeutic approaches for bladder cancer (BCa) are available, but accompanied by unfavorable outcomes. Previous studies reported a potential clinical effect of CAP to prevent BCa tumorigenesis. However, its underlying molecular mechanism still remains unknown. Our transcriptome analysis suggested a close link among calcium signaling pathway, cell cycle regulation, ROS metabolism and FOXO signaling pathway in BCa. In this study, several experiments were performed to investigate the effects of CAP on BCa cells (5637 and T24) and NOD/SCID mice. Our results showed that CAP could suppress BCa tumorigenesis by inhibiting its proliferation both in vitro and in vivo. Moreover, CAP induced cell cycle arrest at G0/G1 phase and ROS production. Importantly, our studies revealed a strong increase of FOXO3a after treatment with CAP. Furthermore, we observed no significant alteration of apoptosis by CAP, whereas Catalase and SOD2 were considerably upregulated, which could clear ROS and protect against cell death. Thus, our results suggested that CAP could inhibit viability and tumorigenesis of BCa possibly via FOXO3a-mediated pathways.

Fatty Acid Profile and Biological Activities of Linseed and Rapeseed Oils

It has been postulated that fatty acids found in edible oils may exert beneficial health effects by the modulation of signaling pathways regulating cell differentiation and proliferation, especially in the treatment of cardiovascular diseases. In the present study, the biological effects of selected edible oils—linseed (LO) and rapeseed (RO) oils—were tested in vitro on fibroblast cells. The fatty acid profile of the oils was determined using gas chromatography and FTIR spectroscopy. LO was found to be rich in α-linolenic acid (ALA), whereas oleic acid was the most abundant species in RO. Fatty acids were taken up by the cells and promoted cell proliferation. No oxidative stress-mediated cytotoxic or genotoxic effects were observed after oil stimulation. Oils ameliorated the process of wound healing as judged by improved migration of fibroblasts to the wounding area. As ALA-rich LO exhibited the most potent wound healing activity, ALA may be considered a candidate for promoting the observed effect.

Neuronal Nitric Oxide Synthase-Mediated Genotoxicity of 2-Methoxyestradiol in Hippocampal HT22 Cell Line

2-methoxyestradiol, metabolite of 17β-estradiol, is considered a potential anticancer agent, currently investigated in several clinical trials. This natural compound was found to be effective towards great number of cancers, including colon, breast, lung, and osteosarcoma and has been reported to be relatively non-toxic towards non-malignant cells. The aim of the study was to determine the potential neurotoxicity and genotoxicity of 2-methoxyestradiol at physiological and pharmacological relevant concentrations in hippocampal HT22 cell line. Herein, we determined influence of 2-methoxyestradiol on proliferation, inhibition of cell cycle, induction of apoptosis, and DNA damage in the HT22 cells. The study was performed using imaging cytometry and comet assay techniques. Herein, we demonstrated that 2-methoxyestradiol, at pharmacologically and also physiologically relevant concentrations, increases nuclear localization of neuronal nitric oxide synthase. It potentially results in DNA strand breaks and increases in genomic instability in hippocampal HT22 cell line. Thus, we are postulating that naturally occurring 2-methoxyestradiol may be considered a physiological modulator of neuron survival.