Mitochondria-mediated apoptosis by diallyl trisulfide in human prostate cancer cells is associated with generation of reactive oxygen species and regulated by Bax/Bak

Diallyl trisulfide induces pyroptosis and impairs lung CSC-like properties by activating the ROS/Caspase 1 signaling pathway

Lung cancer stem cells (CSCs) drive continuous cancer growth and metastatic dissemination; thus, there is an urgent requirement to acquire effective therapeutic strategies for targeting lung CSCs. Diallyl trisulfide (DATS), a garlic organosulfide, possesses suppressive potential in lung cancer; however, its underlying mechanism is still unclear. In this study, we identified DATS as a pyroptosis inducer in lung cancer cells. DATS-treated A549 and H460 cells exhibited pyroptotic cell death, with characteristic large bubbles appearing on their plasma membrane and LDH release. DATS induced cell death, arrested the cell cycle at the G2/M phase, and inhibited colony formation in lung cancer cells. Meanwhile, we found that DATS significantly suppressed the malignant features by impairing lung CSC-like properties, including sphere formation ability, CD133 positive cell number, and lung CSCs marker expression. Mechanistically, DATS induced cell pyroptosis via increasing the expression of NLRP3, ASC, Pro Caspase 1, Cleaved Caspase 1, GSDMD, GSDMD-N, and IL-1β. The verification experiments showed that the effects of DATS on pyroptosis and lung CSC-like properties were weakened after Caspase 1 inhibitor VX-765 treatment, indicating that DATS activated NLRP3 inflammasome-mediated pyroptosis by targeting Caspase 1 in lung cancer cells. Moreover, DATS increased ROS overproduction and mitochondrial dysfunction, which contributed to DATS-induced pyroptosis of lung cancer cells. NAC treatment reversed the effects of DATS on pyroptosis and CSC-like properties. In vivo experiment further confirmed that DATS restrained tumor growth. Together, our results suggest that DATS promotes pyroptosis and impairs lung CSC-like properties by activating ROS/Caspase 1 signaling pathway, thereby retarding lung cancer progression.

The potential role of hydrogen sulfide in cancer cell apoptosis

For a long time, hydrogen sulfide (H2S) has been considered a toxic compound, but recent studies have found that H2S is the third gaseous signaling molecule which plays a vital role in physiological and pathological conditions. Currently, a large number of studies have shown that H2S mediates apoptosis through multiple signaling pathways to participate in cancer occurrence and development, for example, PI3K/Akt/mTOR and MAPK signaling pathways. Therefore, the regulation of the production and metabolism of H2S to mediate the apoptotic process of cancer cells may improve the effectiveness of cancer treatment. In this review, the role and mechanism of H2S in cancer cell apoptosis in mammals are summarized.

The Garlic Compound, Diallyl Trisulfide, Attenuates Benzo[a]Pyrene-Induced Precancerous Effect through Its Antioxidant Effect, AhR Inhibition, and Increased DNA Repair in Human Breast Epithelial Cells

Exposure to B[a]P, the most characterized polycyclic aromatic hydrocarbon, significantly increases breast cancer risk. Our lab has previously reported that diallyl trisulfide (DATS), a garlic organosulfur compound (OSC) with chemopreventive and cell cycle arrest properties, reduces lipid peroxides and DNA damage in normal breast epithelial (MCF-10A) cells. In this study, we evaluated the ability of DATS to block the B[a]P-induced initiation of carcinogenesis in MCF-10A cells by examining changes in proliferation, clonogenic formation, reactive oxygen species (ROS) formation, 8-hydroxy-2-deoxyguanosine (8-OHdG) levels, and protein expression of ARNT/HIF-1β, CYP1A1, and DNA POLβ. The study results indicate that B[a]P increased proliferation, clonogenic formation, ROS formation, and 8-OHdG levels, as well as increasing the protein expression of ARNT/HIF-1β and CYP1A1 compared to the control. Conversely, DATS/B[a]P co-treatment (CoTx) inhibited cell proliferation, clonogenic formation, ROS formation, and 8-OHdG levels compared to B[a]P alone. Treatment with DATS significantly inhibited (p < 0.0001) AhR expression, implicated in the development and progression of breast cancer. The CoTx also attenuated all the above-mentioned B[a]P-induced changes in protein expression. At the same time, it increased DNA POLβ protein expression, which indicates increased DNA repair, thus causing a chemopreventive effect. These results provide evidence for the chemopreventive effects of DATS in breast cancer prevention.

Diallyl Trisulfide Induces ROS-Mediated Mitotic Arrest and Apoptosis and Inhibits HNSCC Tumor Growth and Cancer Stemness

Despite advances in therapeutic approaches, the five-year survival rate for head and neck squamous cell carcinoma (HNSCC) patients is still less than fifty percent. Research has indicated that the consumption of Allium vegetables or processed garlic containing diallyl trisulfide (DATS) can lower the risk of multiple types of cancer. Nevertheless, the effectiveness and underlying mechanisms of DATS against HNSCC have not been thoroughly explored until the current study. In this research, it was found that DATS notably curtailed the growth and viability of HNSCC cells. Additionally, DATS triggered a significant G2/M cell cycle arrest in these cells, accumulating cyclin B1, Cip1/p21, and Ser-10 phospho-histone H3-this was indicative of mitotic arrest attenuated by NAC pretreatment, suggesting the role of reactive oxygen species (ROS) induction. The production of ROS induced by DATS led to DNA damage and apoptosis, a process associated with elevated levels of cleaved caspase-3 and cleaved PARP, along with reduced XIAP. When HNSCC cells were exposed to pharmacological concentrations of DATS, it resulted in the suppression of cancer stem cell (CSC) populations, as indicated by a decrease in the CD133high/CD44high cell fraction, reduced aldehyde dehydrogenase 1 (ALDH1) activity, inhibited spheroid formation and downregulated SOX2 and Oct4 expression. Furthermore, the administration of DATS to tumor xenografts demonstrated its in vivo capacity to hinder CSCs. Further, DATS treatment inhibited the growth of UMSCC-22B head and neck cancer tumor xenograft in immunocompromised mice. Overall, DATS inhibited cell proliferation; induced cell cycle mitotic arrest and apoptosis involving DNA damage through ROS generation; reduced the CSC fraction and spheroid formation; and downregulated SOX2 and Oct4 expression. More importantly, DATS inhibited HNSCC tumor growth and CSC fraction in vivo. Thus, DATS could be a potential anticancer agent that can be used against head and neck cancer.

Rosmarinic acid, the active component of Rubi Fructus, induces apoptosis of SGC-7901 and HepG2 cells through mitochondrial pathway and exerts anti-tumor effect

Rosmarinic acid (RA) is a well-known phenolic acid widely present in over 160 species of herbal plants and known to exhibit anti-tumor effects on breast, prostate, and colon cancers in vitro. However, its effect and mechanism in gastric cancer and liver cancer are unclear. Moreover, there is no RA report yet in the chemical constituents of Rubi Fructus (RF). In this study, RA was isolated from RF for the first time, and the effect and mechanism of RA on gastric and liver cancers were evaluated using SGC-7901 and HepG2 cells models. The cells were treated with different concentrations of RA (50, 75, and 100 μg/mL) for 48 h, and the effect of RA on cell proliferation was evaluated by the CCK-8 assay. The effect of RA on cell morphology and mobility was observed by inverted fluorescence microscopy, cell apoptosis and cell cycle were determined by flow cytometry, and the expression of apoptosis-related proteins cytochrome C, cleaved caspase-3, Bax, and Bcl-2 was detected by western blotting. The results revealed that, with an increase in the RA concentration, the cell viability, mobility, and Bcl-2 expression decreased, while the apoptosis rate, Bax, cytochrome C, and cleaved caspase-3 expression increased, and SGC-7901 and HepG2 cells could be induced to arrest their cell cycle in the G0/G1 and S phases, respectively. These results together indicate that RA can induce apoptosis of SGC-7901 and HepG2 cells through the mitochondrial pathway. Thus, this study supplements the material basis of the anti-tumor activity of RF and provides an insight into the potential mechanism of RA-inducing apoptosis of gastric cancer SGC-7901 cells and liver cancer HepG2 cells, thereby facilitating further developmental studies on and the utilization of the anti-tumor activity of RF.

Diallyl trisulfide alleviates chemotherapy sensitivity of ovarian cancer via the AMPK/SIRT1/PGC1α pathway

Platinum-based chemotherapy promotes drug resistance in ovarian cancer. We investigated the antichemoresistance characteristics of diallyl trisulfide (DATS) in cisplatin-resistant ovarian cancer cells, in vitro and in vivo. Previous preclinical studies have revealed that DATS regulates distinct hallmark cancer-signaling pathways. The cell cycle pathway is the most investigated signaling pathway in DATS. Additionally, post-DATS treatment has been found to promote proapoptotic capacity through the regulation of intrinsic and extrinsic apoptotic pathway components. In the present study, we found that treating cisplatin-sensitive and cisplatin-resistant ovarian cell lines with DATS inhibited their proliferation and reduced their IC_50. It induced cell apoptosis and promoted oxidative phosphorylation through the regulation of the AMPK/SIRT1/PGC1α pathway, OXPHOS, and enhanced chemotherapy sensitivity. DATS treatment alleviated glutamine consumption in cisplatin-resistant cells. Our findings highlight the role of DATS in overcoming drug resistance in ovarian cancer in vitro and in vivo. In addition, we elucidated the role of the AMPK/SIRT1/PGC1α signaling pathway as a potential target for the treatment of drug-resistant ovarian cancer.

In vitro anti-synovial sarcoma effect of diallyl trisulfide and mRNA profiling

OBJECTIVE

Synovial sarcoma (SS) is a malignant soft tissue sarcoma and its natural history is a long, indolent clinical course followed by high rate of local recurrence and distant metastasis. Current therapies are still limited in increasing satisfactory of 5-year survival, especially for patients with recurrence and metastasis. Accordingly, finding new therapeutic drug for SS treatment is clinically urgent need. Diallyl trisulfide (DATS), a bioactive compound derived from garlic, is reported as a promising anti-cancer agent for various carcinomas. However, its effect on anti-SS remains unknown. This study investigated the anti-SS effect of DATS in human synovial sarcoma SW982 cells.

METHODS

CCK-8 assay were used to examine the cell viability. High-content Imaging System was used to examine the apoptosis, intracellular ROS and autophagy. Flow cytometry was used to detect cell cycle. qPCR and Western blot were used to examine the expression of related mRNA and protein. High-throughput RNA-sequencing and bio-information analysis were used to investigate the mRNA profiling.

RESULTS

The results showed a suppressive effect of DATS on tumor biology of SW982 cells including inducing apoptosis, triggering G2/M cell cycle arrest, elevating intracellular ROS and damaging mitochondria. Further high-throughput RNA-sequencing analysis clarified a comprehensive molecular portrait for DATS-induced transcriptional regulation. Besides, protein-protein interaction (PPI) analysis demonstrated that a network consisted of FOXM1, CCNA2, CCNB1, MYBL2, PLK1 and CDK1 might be response for DATS-induced G2/M cell cycle arrest and increased intracellular ROS. Notably, protein feature analysis revealed structure enrichment in microtubule network like kinesin motors domain, and tubulin domain. Molecular function analysis suggested that DATS-induced dysfunction of microtubule network might be the major cause for its effect on cell cycle arrest and successive apoptosis. Furthermore, 28 hub genes (including KIF2C, PLK1, CDK1, BIRC5, CCNB2, CENPF, TPX2, TOP2A and so on) were determined. Finally, pathway analysis showed that DATS-induced differentially expressed genes were mainly involved in cell cycle.

CONCLUSION

Collectively, our findings for the first time provided the DATS-induced cellular response and transcriptional profiling of SW982 cells, which proposes that suppression of DATS on SS is multi-targeted and represent a therapeutic evidence for SS.

Diallyl Sulfide Attenuation of Carcinogenesis in Mammary Epithelial Cells through the Inhibition of ROS Formation, and DNA Strand Breaks

Garlic has long been used medicinally for many diseases, including cancer. One of the active garlic components is diallyl sulfide (DAS), which prevents carcinogenesis and reduces the incidence rate of several cancers. In this study, non-cancerous MCF-10A cells were used as a model to investigate the effect of DAS on Benzo (a)pyrene (BaP)-induced cellular carcinogenesis. The cells were evaluated based on changes in proliferation, cell cycle arrest, the formation of peroxides, 8-hydroxy-2-deoxyguanosine (8-OHdG) levels, the generation of DNA strand breaks, and DNA Polymerase β (Pol β) expression. The results obtained indicate that when co-treated with BaP, DAS inhibited BaP-induced cell proliferation (p < 0.05) to levels similar to the negative control. BaP treatment results in a two-fold increase in the accumulation of cells in the G2/M-phase of the cell cycle, which is restored to baseline levels, similar to untreated cells and vehicle-treated cells, when pretreated with 6 μM and 60 μM DAS, respectively. Co-treatment with DAS (60 μM and 600 μM) inhibited BaP-induced reactive oxygen species (ROS) formation by 132% and 133%, respectively, as determined by the accumulation of H₂O₂ in the extracellular medium and an increase in 8-OHdG levels of treated cells. All DAS concentrations inhibited BaP-induced DNA strand breaks through co-treatment and pre-treatment methods at all time points evaluated. Co-Treatment with 60 μM DAS increased DNA Pol β expression in response to BaP-induced lipid peroxidation and oxidative DNA damage. These results indicate that DAS effectively inhibited BaP-induced cell proliferation, cell cycle transitions, ROS, and DNA damage in an MCF-10A cell line. These results provide more experimental evidence for garlic's antitumor abilities and corroborate many epidemiological studies regarding the association between the increased intake of garlic and the reduced risk of several types of cancer.

Improving the bioavailability and bioactivity of garlic bioactive compounds via nanotechnology

This review highlights main bioactive compounds and important biological functions especially anticancer effects of the garlic. In addition, we review current literature on the stability and bioavailability of garlic components. Finally, this review aims to provide a potential strategy for using nanotechnology to increase the stability and solubility of garlic components, providing guidelines for the qualities of garlic products to improve their absorption and prevent their early degradation, and extend their circulation time in the body. The application of nanotechnology to improve the bioavailability and targeting of garlic compounds are expected to provide a theoretical basis for the functional components of garlic to treat human health. We review the improvement of bioavailability and bioactivity of garlic bioactive compounds via nanotechnology, which could promisingly overcome the limitations of conventional garlic products, and would be used to prevent and treat cancer and other diseases in the near future.

Anticancer potential of garlic and its bioactive constituents: A systematic and comprehensive review

Vegetables of the Allium genus, such as garlic (Allium sativum L.), onions, shallots, leaks, and chives, have been used for many years for food consumption and for medicinal purposes. Historical medical texts have indicated the therapeutic applications of garlic as an antitumor, laxative, diuretic, antibacterial and antifungal agent. Specifically, garlic's antitumor abilities have been traced back 3500 years as a chemotherapeutic agent used in Egypt. Other beneficial effects of garlic consumption include lowering blood pressure, blood cholesterol, sugar and lipids. The processing and aging of garlic result in the production of non-toxic organosulfur by-products. These sulfur-containing compounds, such as allicin, diallyl sulfide, diallyl disulfide, diallyl trisulfide, alliin, S-allylcysteine, and S-allylmercaptocysteine, impact various stages of carcinogenesis. The anticancer mechanisms of action of these garlic-derived phytochemicals include altering mitochondrial permeability, inhibiting angiogenesis, enhancing antioxidative and proapoptotic properties, and regulating cell proliferation. All these effects of garlic's sulfur-compounds have been demonstrated in various human cancers. The intent of this literature research is to explore the potential of garlic-derived products and bioactive organosulfur compounds as cancer chemopreventive and chemotherapeutic agents. This investigation employs criteria for systematic review and critically analyzes published in vitro, in vivo and clinical studies. Concerns and limitations that have arisen in past studies regarding standards of measurement, bioavailability, and method of delivery are addressed. Overall, it is hoped that through this systematic and comprehensive review, future researchers can be acquainted with the updated data assembled on anticancer properties of garlic and its phytoconstituents.

Redox Modulation at Work: Natural Phytoprotective Polysulfanes From Alliums Based on Redox-Active Sulfur

Purpose of review

This article provides a brief overview of natural phytoprotective products of allium with a special focus on the therapeutic potential of diallyl polysulfanes from garlic, their molecular targets and their fate in the living organisms. A comprehensive overview of antimicrobial and anticancer properties of published literature is presented for the reader to understand the effective concentrations of polysulfanes and their sensitivity towards different human pathogenic microbes, fungi, and cancer cell lines.

Recent findings

The article finds polysulfanes potentials as new generation novel antibiotics and chemo preventive agent. The effective dose rates of polysulfanes for antimicrobial properties are in the range of 0.5-40 mg/L and for anticancer 20-100 μM. The molecular targets for these redox modulators are mainly cellular thiols as well as inhibition and/or activation of certain cellular proteins in cancer cell lines.

Summary

Antimicrobial and anticancer activities of polysulfanes published in the literature indicate that with further development, they could be promising candidates for cancer prevention due to their selectivity towards abnormal cells.

Protective and Restorative Effects of Nutrients and Phytochemicals

Intoroduction:

Dietary intake fundamentally provides reintegration of energy and essential nutrients to human organisms. However, its qualitative and quantitative composition strongly affects individual’s health, possibly being either a preventive or a risk factor. It was shown that nutritional status resulting from long-term exposition to specific diet formulations can outstandingly reduce incidences of most common and most important diseases of the developed world, such as cardiovascular and neoplastic diseases. Diet formulations result from different food combinations which bring specific nutrient molecules. Numerous molecules, mostly but not exclusively from vegetal foods, have been characterized among nutritional components as being particularly responsible for diet capabilities to exert risk reduction. These “bioactive nutrients” are able to produce effects which go beyond basic reintegration tasks, i.e. energetic and/or structural, but are specifically pharmacologically active within pathophysiological pathways related to many diseases, being able to selectively affect processes such as cell proliferation, apoptosis, inflammation, differentiation, angiogenesis, DNA repair and carcinogens activation.

Conclusion:

The present review was aimed to know the molecular mechanisms and pathways of activity of bioactive molecules; which will firstly allow search for optimal food composition and intake, and then use them as possible therapeutical targets and/or diagnostics. Also, the present review discussed the therapeutic effect of both nutrients and phytochemicals.

Green silver nanoparticles as a multifunctional sensor for toxic Cd(ii) ions

Silver nanoparticles (AgNPs) were synthesized using Allium sativum (AS) extract. The AgNP-AS was able to detect Cd(ii) ions with various techniques such as optical, fluorescence and electrochemical sensing. The limit of detection was found to be 0.277 μM. Silver nanoparticles were able to quantify Cd(ii) ions from environmental samples. The antibacterial activity of AgNP-AS was explored towards waterborne bacteria.

Mitochondrial ROS activates ERK/autophagy pathway as a protected mechanism against deoxypodophyllotoxin-induced apoptosis

Deoxypodophyllotoxin (DPT) is a naturally occurring flavolignan isolated from Anthriscus sylvestris. Recently, it has been reported that DPT inhibits tubulin polymerization and induces G2/M cell cycle arrest followed by apoptosis through multiple cellular processes. Despite these findings, details regarding the cellular and molecular mechanisms underlying the DPT-mediated cell death have been poorly understood. To define a mechanism of DPT-mediated cell death response, we examined whether DPT activates signaling pathways for autophagy and apoptosis. We demonstrated that DPT inhibited cell viability and induced apoptosis in prostate cancer cell lines, as evidenced by a mitochondrial membrane potential and expression of apoptosis-related proteins. Reactive oxygen species (ROS), primarily generated from the mitochondria, play an important role in various cellular responses, such as apoptosis and autophagy. DPT significantly triggered mitochondrial ROS, which were detected by MitoSOX, a selective fluorescent dye of mitochondria-derived ROS. Furthermore, DPT induced autophagy through an up-regulation of autophagic biomarkers, including a conversion of microtubule-associated protein 1 light chain 3 - I (LC3-I) into LC3-II and a formation of acidic vesicular organelles. Moreover, mitochondrial ROS promoted AKT-independent autophagy and ERK signaling. The inhibition of autophagy with 3-methyladenine or LC3 knockdown enhanced DPT-induced apoptosis, suggesting that an autophagy plays a protective role in cell survival against apoptotic prostate cancer cells. Additionally, the results from an in vivo xenograft model confirmed that DPT inhibited tumor growth by regulating the apoptosis- and autophagy-related proteins.

A possible mechanism of inhibition of U87MG and SH-SY5Y cancer cell proliferation by diallyl trisulfide and other aspects of its activity

The study was conducted to elucidate the mechanism of antiproliferative and antioxidative action of diallyl trisulfide (DATS), a garlic-derived organosulfur compound. Changes in the l-cysteine desulfuration, and the levels of cystathionine and non-protein thiols in DATS-treated human glioblastoma (U87MG) and neuroblastoma (SH-SY5Y) cells were investigated. The inhibition of proliferation of the investigated cells by DATS was correlated with an increase in the inactivated form of Bcl-2. In U87MG cells, an increased level of sulfane sulfur and an increased activity of 3-mercaptopyruvate sulfurtransferase (MPST) and rhodanese, the enzymes involved in sulfane sulfur generation and transfer, suggest that DATS can function as a donor of sulfane sulfur atom, transferred by sulfurtransferases, to sulfhydryl groups of cysteine residues of Bcl-2 and in this way lower the level of active form of Bcl-2 by S-sulfuration. Diallyl trisulfide antioxidative effects result from an increased level of cystathionine, a precursor of cysteine, and an increased glutathione level. MPST and rhodanese, the level of which is increased in the presence of DATS, can serve as antioxidant proteins.

Dietary Bioactive Diallyl Trisulfide in Cancer Prevention and Treatment

Bioactive dietary agents have been shown to regulate multiple cancer hallmark pathways. Epidemiologic studies have linked consumption of Allium vegetables, such as garlic and onions, to decreased incidence of cancer. Diallyl trisulfide (DATS), a bioactive compound derived from Allium vegetables, has been investigated as an anti-cancer and chemopreventive agent. Preclinical studies provide ample evidence that DATS regulates multiple cancer hallmark pathways including cell cycle, apoptosis, angiogenesis, invasion, and metastasis. DATS has been shown to arrest cancer cells at multiple stages of the cell cycle with the G2/M arrest being the most widely reported. Additionally, increased pro-apoptotic capacity as a result of regulating intrinsic and extrinsic apoptotic pathway components has been widely reported following DATS treatment. Invasion, migration, and angiogenesis represent emerging targets of DATS and support its anti-cancer properties. This review summarizes DATS mechanisms of action as an anti-cancer and chemopreventive agent. These studies provide rationale for future investigation into its use as a cancer chemopreventive agent.

S-Allylmercaptocysteine induces G2/M phase arrest and apoptosis via ROS-mediated p38 and JNK signaling pathway in human colon cancer cells in vitro and in vivo

SAMC inhibits colon cancer cell growth through the reactive oxygen species-dependent pathway.

The cellular death pattern of primary haemocytes isolated from the black tiger shrimp (Penaeus monodon)

A key to successfully generate the penaeid shrimp cell line is to find out how primary cells died. The most suitable period to culture Penaeus monodon haemocytes was in the first 48 h of culture because cells had normal morphology, high percent of viable cells (65.29 ± 5.43%), low percent of early (11.75 ± 1.30%) and late apoptotic cells (15.47 ± 11.71%) determined by Annexin V and TUNEL including constant IAP (0.06 ± 0.01-0.07 ± 0.01) and caspase-3 expression (0.30 ± 0.06-0.39 ± 0.10) by real-time PCR throughout the experiment. Moreover, adding 50 and 250 μM of the cell permeable pan caspase inhibitor Z-VAD-FMK produced some melanised cells since the 48(th) hour, while percent of viable cells was decreased since the 24(th) hour with no difference in percent of early and late apoptotic cells compared to control at each time point. No difference of IAP and caspase-3 expression level in both Z-VAD-FMK groups was found compared to control and vehicle groups at each time point, excluding caspase-3 in 250 μM Z-VAD-FMK at the 24(th) hour was higher than control and vehicle. Supplementing sodium fluoride (NaF) induced cell membrane damage and cellular shrinkage of primary haemocytes within 2 h. Even percent of viable cells was reduced down to zero and percent of late apoptotic cells was increased by 2 h of incubation in 25 and 50 mM NaF, IAP and caspase-3 in all NaF groups was not different from control. These results indicate that a number of primary haemocytes derived in this study die through the apoptotic process.

NKCT1 (purified Naja kaouthia protein toxin) conjugated gold nanoparticles induced Akt/mTOR inactivation mediated autophagic and caspase 3 activated apoptotic cell death in leukemic cell

BACKGROUND

Gold nanoparticle (GNP) and snake venom protein toxin NKCT1 was conjugated as stated earlier (Bhowmik et al., 2013). The aim of this study was to explore the caspase dependent apoptotic pathway and autophagy inducing ability of gold nanoparticles tagged snake venom protein toxin NKCT1 (GNP-NKCT1) in human leukemic U937 and K562 cell line.

METHODS

GNP-NKCT1 induced apoptosis in U937 and K562 cell line were assessed through mitochondrial membrane potential assay, ROS generation assay, caspase 3 pathways and western blotting. GNP-NKCT1 induced autophagic pathway was detected through Akt, mTOR and PI3K expression by western blotting. Autophagic cell death also checked after addition of caspase 3 inhibitor and which also reconfirmed by western blotting of autophagic marker protein, lysosomal staining.

RESULTS

Loss of mitochondrial membrane potential was occurred in both the leukemic cell line after induction by GNP-NKCT1 and treatment of which also exhibited high ROS generation. Caspase 3 expression of cell was also increased. With caspase 3 inhibitor, GNP-NKCT1 downregulated PI3K/Akt and mTOR expression and thus undergoing autophagic cell death. Lysosomal staining confirmed lysosomal enzyme involvement in the autophagic response. Up regulation of Atg 3, Atg12, Beclin 1, LC3-II protein and BIF-1 and down regulation of Atg4B were also showed by blotting.

CONCLUSION

The results demonstrated that conjugation of Gold nanoparticles with NKCT1 could induce an alternate cell death pathway other than apoptosis in the form of autophagy in leukemic cell.

GENERAL SIGNIFICANCE

This study might provide the understanding area of chemotherapeutic drug development from natural resources like snake venoms.

Diallyl trisulfide induces osteosarcoma cell apoptosis through reactive oxygen species-mediated downregulation of the PI3K/Akt pathway

Diallyl trisulfide (DATS) is a natural organosulfur compound isolated from garlic, and has been reported to possess anticancer activities. However, the cancer growth inhibitory effects and molecular mechanisms in human osteosarcoma cells have not been well studied. The present study demonstrated that DATS significantly reduced cell viability in a dose- and time-dependent manner in MG63 and MNNG/HOS cells. DATS-induced G0/G1 phase arrest was found to correlate with a decrease in cyclin D1 in concomitance with an increase in p21 and p27. DATS induced a marked increase in reactive oxygen species (ROS) levels and collapse of mitochondrial membrane potential (Δψm) in the osteosarcoma cells. DATS induced apoptosis in the MG63 and MNNG/HOS cells via inhibition of the PI3K/Akt signaling pathway and through the mitochondrial apoptotic pathway. The efficiency of DATS basically approached the efficacy of LY294002, a specific PI3K inhibitor. However, N-acetylcysteine (NAC), a general ROS scavenger, completely blocked the DATS-induced ROS increase, inhibition of the PI3K/Akt pathway and cell apoptosis. Overall, DATS has the potential to be developed as a new anticancer drug. The mechanisms of action involve the ROS-mediated downregulation of the PI3K/Akt pathway.

Hydrogen Sulfide Signaling Axis as a Target for Prostate Cancer Therapeutics

Hydrogen sulfide (H₂S) was originally considered toxic at elevated levels; however just in the past decade H₂S has been proposed to be an important gasotransmitter with various physiological and pathophysiological roles in the body. H₂S can be generated endogenously from L-cysteine by multiple enzymes, including cystathionine gamma-lyase, cystathionine beta-synthase, and 3-mercaptopyruvate sulfurtransferase in combination with cysteine aminotransferase. Prostate cancer is a major health concern and no effective treatment for prostate cancers is available. H₂S has been shown to inhibit cell survival of androgen-independent, androgen-dependent, and antiandrogen-resistant prostate cancer cells through different mechanisms. Various H₂S-releasing compounds, including sulfide salts, diallyl disulfide, diallyl trisulfide, sulforaphane, and other polysulfides, also have been shown to inhibit prostate cancer growth and metastasis. The expression of H₂S-producing enzyme was reduced in both human prostate cancer tissues and prostate cancer cells. Androgen receptor (AR) signaling is indispensable for the development of castration resistant prostate cancer, and H₂S was shown to inhibit AR transactivation and contributes to antiandrogen-resistant status. In this review, we summarized the current knowledge of H₂S signaling in prostate cancer and described the molecular alterations, which may bring this gasotransmitter into the clinic in the near future for developing novel pharmacological and therapeutic interventions for prostate cancer.

Anticancer effect of 2,7-dihydroxy-3-methylanthraquinone on human gastric cancer SGC-7901 cells in vitro and in vivo

CONTEXT

2,7-Dihydroxy-3-methylanthraquinone (DDMN) is reported to have a remarkable anticancer activity against gastric cancer SGC-7901 cells.

OBJECTIVE

The objective of this study is to study the anticancer effect and mechanism of DDMN on SGC-7901 cells.

MATERIALS AND METHODS

The MTT assay was used to determine the effect of DDMN on cell viability of SGC-7901 cells, and the cytotoxic effect was evaluated by the IC50 value. After treatment with different doses of DDMN (10, 20, and 40 μM) for 48 h, flow cytometry was used to investigate the apoptosis of SGC-7901 cells induced by DDMN. Further, western blotting was performed to study anticancer mechanism by assaying apoptosis-related proteins containing Mcl-1, Bcl-xl, Bcl-2, Bax, Bak, Bad, cytochrome c, caspase-3, and caspase-9. Finally, xenograft assay was used to further evaluate the effect of DDMN on SGC-7901 cells by determining body weight of nude mice, tumor volumes, and apoptosis-related proteins.

RESULTS

These results suggest that DDMN can significantly inhibit (IC50 value = 20.92 μM) the proliferation of SGC-7901 cells and induce apoptosis of SGC-7901 cells demonstrated by flow cytometry analysis. Additionally, the results of western blotting indicated that DDMN can suppress the expression of anti-apoptotic proteins Bcl-xl and Bcl-2, increase the expression of pro-apoptotic proteins Bax, Bad (40 μM), caspase-3 and caspase-9, and evidently promote the release of cytochrome c from the mitochondria to the cytoplasm. The xenograft assay further confirmed that DDMN had significant anticancer effects on SGC-7901 cells.

CONCLUSION

DDMN had significant anticancer effect on SGC-7901 cells in vitro and in vivo related to mitochondria-mediated apoptosis.

Crude Garlic Extract Inhibits Cell Proliferation and Induces Cell Cycle Arrest and Apoptosis of Cancer Cells In Vitro

Garlic and its lipid-based extracts have played an important medicinal role in humans for centuries that includes antimicrobial, hypoglycemic, and lipid-lowering properties. The present study was to investigate the effects of crude garlic extract (CGE) on the proliferation of human breast, prostate, hepatic, and colon cancer cell lines and mouse macrophageal cells, not previously studied. The human cancer cell lines, such as hepatic (Hep-G2), colon (Caco-2), prostate (PC-3), and breast (MCF-7), were propagated at 37°C; air/CO2 (95:5 v/v) using the ATCC-formulated RPMI-1640 Medium and 10% fetal bovine serum (FBS), while the mouse macrophage cell line (TIB-71) was propagated at 37°C; air/CO2 (95:5 v/v) using the ATCC-formulated DMEM and 10% FBS. All cells were plated at a density of ∼5000 cells/well. After overnight incubation, the cells were treated with 0.125, 0.25, 0.5, or 1 μg/mL of CGE an additional 72 h. Inhibition of cell proliferation of 80-90% was observed for Hep-G2, MCF-7, TIB-71, and PC-3 cells, but only 40-55% for the Caco-2 cells when treated with 0.25, 0.5, or 1 μg/mL. In a coculture study of Caco-2 and TIB-71 cells, inhibition of cell proliferation of 90% was observed for Caco-2 cells compared to the 40-55% when cultured separately. CGE also induced cell cycle arrest and had a fourfold increase in caspase activity (apoptosis) in PC-3 cells when treated at a dose of 0.5 or 1 μg/mL. This investigation of CGE clearly highlights the fact that the lipid bioactive compounds in CGE have the potential as promising anticancer agents.

Down-regulation of miR-150 induces cell proliferation inhibition and apoptosis in non-small-cell lung cancer by targeting BAK1 in vitro

Non-small-cell lung cancer (NSCLC) is one of the most common causes of cancer-related death. Our investigations show that miR-150 is a typical microRNA that is overexpressed in human NSCLC. We characterized the effects of miR-150 overexpression in NSCLC cells and found that down-regulation of miR-150 expression inhibited cell proliferation and induced cell apoptosis in vitro; additionally, up-regulation of miR-150 levels had the opposite effect on tumor growth and progression. Furthermore, we found that the mechanism of the miR-150 effects on NSCLC cells was associated with alterations in the expression of human BRI1-associated receptor kinase 1 (BAK1). miR-150 may function as an oncogene in NSCLC cells by directly targeting BAK1. Thus, these data highlight a novel molecular interaction between miR-150 and BAK1 and provide a novel strategy for NSCLC therapy via the down-regulation of miR-150 expression.

The strategies to control prostate cancer by chemoprevention approaches

Prostate cancer (PCA) is the most commonly diagnosed cancer in men in the United States with growing worldwide incidence. Despite intensive investment in improving early detection, PCA often escapes timely detection and mortality remains high; this malignancy being the second highest cancer-associated mortality in American men. Collectively, health care costs of PCA results in an immense financial burden that is only expected to grow. Additionally, even in cases of successful treatment, PCA is associated with long-term and pervasive effects on patients. A proactive alternative to treat PCA is to prevent its occurrence and progression prior to symptomatic malignancy. This may serve to address the issue of burgeoning healthcare costs and increasing number of sufferers. One potential regimen in service of this alternative is PCA chemoprevention. Here, chemical compounds with cancer preventive efficacy are identified on the basis of their potential in a host of categories: their historical medicinal use, correlation with reduced risk in population studies, non-toxicity, their unique chemical properties, or their role in biological systems. PCA chemopreventive agents are drawn from multiple broad classes of chemicals, themselves further subdivided based on source or potential effect, with most derived from natural products. Many such compounds have shown efficacy, varying from inhibiting deregulated PCA cell signaling, proliferation, epithelial to mesenchymal transition (EMT), invasion, metastasis, tumor growth and angiogenesis and inducing apoptosis. Overall, these chemopreventive agents show great promise in PCA pre-clinical models, though additional work remains to be done in effectively translating these findings into clinical use.

Terfenadine induces anti-proliferative and apoptotic activities in human hormone-refractory prostate cancer through histamine receptor-independent Mcl-1 cleavage and Bak up-regulation

Although the results of several studies have underscored the regulatory effect of H1-histamine receptors in cell proliferation of some cancer cell types, its effect in prostate cancers remains unclear. We have therefore studied the effect of terfenadine (an H1-histamine receptor antagonist) in prostate cancer cell lines. Our data demonstrate that terfenadine was effective against PC-3 and DU-145 cells (two prostate cancer cell lines). In contrast, based on the sulforhodamine B assay, loratadine had less potency while fexofenadine and diphenhydramine had little effect. Terfenadine induced the cleavage of Mcl-1 cleavage into a pro-apoptotic 28-kDa fragment and up-regulation of Bak, resulting in the loss of mitochondrial membrane potential (ΔΨm) and the release of cytochrome c and apoptosis-inducing factor into the cytosol. The activation of caspase cascades was detected to be linked to terfenadine action. Bak up-regulation was also examined at both the transcriptional and translational levels, and Bak activation was validated based on conformational change to expose the N terminus. Terfenadine also induced an indirect-but not direct-DNA damage response through the cleavage and activation of caspase-2, phosphorylation and activation of Chk1 and Chk2 kinases, phosphorylation of RPA32 and acetylation of Histone H3; these processes were highly correlated to severe mitochondrial dysfunction and the activation of caspase cascades. In conclusion, terfenadine induced apoptotic signaling cascades against HRPCs in a sequential manner. The exposure of cells to terfenadine caused the up-regulation and activation of Bak and the cleavage of Mcl-1, leading to the loss of ΔΨm and activation of caspase cascades which further resulted in DNA damage response and cell apoptosis.

Critical role for reactive oxygen species in apoptosis induction and cell migration inhibition by diallyl trisulfide, a cancer chemopreventive component of garlic

Diallyl trisulfide (DATS) is a structurally simple but biologically active constituent of processed garlic with in vivo activity against chemically induced as well as oncogene-driven cancer in experimental rodents. This study offers novel insights into the mechanisms underlying anticancer effects of DATS using human breast cancer cells as a model. Exposure of human breast cancer cells (MCF-7 and MDA-MB-231) and a cell line derived from spontaneously developing mammary tumor of a transgenic mouse (BRI-JM04) to DATS resulted in a dose-dependent inhibition of cell viability that was accompanied by apoptosis induction. A non-tumorigenic normal human mammary cell line (MCF-10A) was resistant to growth inhibition and apoptosis induction by DATS. The DATS-induced apoptosis in MDA-MB-231, MCF-7, and BRI-JM04 cells was associated with reactive oxygen species (ROS) production as evidenced by fluorescence microscopy and flow cytometry using a chemical probe (MitoSOX Red). Overexpression of Cu,Zn-superoxide dismutase (Cu,Zn-SOD) as well as Mn-SOD conferred significant protection against DATS-induced ROS production and apoptotic cell death in MDA-MB-231 and MCF-7 cells. Activation of Bak, but not Bax, resulting from DATS treatment was markedly suppressed by overexpression of Mn-SOD. The DATS treatment caused ROS generation, but not activation of Bax or Bak, in MCF-10A cells. Furthermore, the DATS-mediated inhibition of cell migration was partially but significantly attenuated by Cu,Zn-SOD and Mn-SOD overexpression in association with changes in levels of proteins involved in epithelial-mesenchymal transition. The DATS-mediated induction of heme oxygenase-1 was partially attenuated by overexpression of Mn-SOD. These results provide novel mechanistic insights indicating a critical role for ROS in anticancer effects of DATS.

Diallyl trisulfide sensitizes human melanoma cells to TRAIL-induced cell death by promoting endoplasmic reticulum-mediated apoptosis

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is promising for cancer treatment because of its selective cytotoxicity toward tumor cells. However, some cancer cell types including malignant melanoma cells are resistant to TRAIL cytotoxicity. Here, we show that diallyl trisulfide (DATS), a garlic organosulfur compound, sensitizes melanoma cells to TRAIL-induced apoptosis while sparing normal cells. DATS also potentiates apoptosis induced by agonistic antibodies against death receptors (DR) 4 and DR5. The amplification of DR-mediated apoptosis was associated with increased mitochondrial membrane potential collapse and caspase-3/7 activation. However, these events were not sufficient for full sensitization. TRAIL also induced endoplasmic reticulum (ER) stress, as indicated by the activation of X-box-binding protein 1 and caspase-12 and DATS poten-tiated both events. Moreover, inhibition of caspase-12, but not caspase-4, abolished the amplification of apoptosis, indicating that ER stress plays a crucial role. On the other hand, DATS and/or TRAIL induced minimal apoptosis and caspase-12 activation in melanocytes despite their substantial expression of DR4 and DR5 on the cell surface. Our data suggest that DATS amplifies death ligand-induced melanoma cell death by disrupting their adaptation to ER-mediated death pathway. The present findings raise the possibility that DATS may be combined with death ligands to treat TRAIL-resistance melanoma cells without impairing its tumor selectivity.

ROS-independent JNK activation and multisite phosphorylation of Bcl-2 link diallyl tetrasulfide-induced mitotic arrest to apoptosis

Garlic-derived organosulfur compounds including diallyl polysulfides are well known for various health-beneficial properties and recent reports even point to a potential role of diallyl polysulfides as chemopreventive and therapeutic agents in cancer treatment due to their selective antiproliferative effects. In this respect, diallyl tri- and tetrasulfide are reported as strong inducers of an early mitotic arrest and subsequent apoptosis, but the underlying molecular mechanisms and the link between these two events are not yet fully elucidated. Our data revealed that diallyl tetrasulfide acts independently of reactive oxygen species and tubulin represents one of its major cellular targets. Tubulin depolymerization prevents the formation of normal spindle microtubules, thereby leading to G2/M arrest. Here, we provide evidence that c-jun N-terminal kinase, which is activated early in response to diallyl tetrasulfide treatment, mediates multisite phosphorylation and subsequent proteolysis of the anti-apoptotic protein B-cell lymphoma 2. As the latter event occurs concomitantly with the onset of apoptosis and the chemical c-jun N-terminal kinase inhibitor SP600125 not only prevented B-cell lymphoma 2 phosphorylation and proteolysis but also apoptosis following diallyl tetrasulfide treatment, we suggest that these c-jun N-terminal kinase-mediated modulations of B-cell lymphoma 2 represent the missing link connecting early microtubule inactivation to the induction of apoptosis.

Hydrogen sulfide in biochemistry and medicine

SIGNIFICANCE

An abundance of experimental evidence suggests that hydrogen sulfide (H(2)S) plays a prominent role in physiology and pathophysiology. Many targets exist for H(2)S therapy. The molecular targets of H(2)S include proteins, enzymes, transcription factors, and membrane ion channels.

RECENT ADVANCES

Novel H(2)S precursors are being synthesized and discovered that are capable of releasing H(2)S in a slow and sustained manner. This presents a novel and advantageous approach to H(2)S therapy for treatment of chronic conditions associated with a decline in endogenous H(2)S, such as diabetes and cardiovascular disease.

CRITICAL ISSUES

While H(2)S is cytoprotective at physiological concentrations, it is not universally cytoprotective, as it appears to have pro-apoptotic actions in cancer cells and is well known to be toxic at supraphysiological concentrations. Many of the pleiotropic effects of H(2)S on health are associated with the inhibition of inflammation and upregulation of prosurvival pathways. The powerful anti-inflammatory, cytoprotective, immunomodulating, and trophic effects of H(2)S on the vast majority of normal cells seem to be mediated mainly by its actions as an extremely versatile direct and indirect antioxidant and free radical scavenger. While the overall effects of H(2)S on transformed (i.e., malignant) cells can be characterized as pro-oxidant and pro-apoptotic, they contrast sharply with the cytoprotective effects on most normal cells.

FUTURE DIRECTIONS

H(2)S has become a molecule of great interest, and several slow-releasing H(2)S prodrugs are currently under development. We believe that additional agents regulating H(2)S bioavailability will be developed during the next 10 years.

Apoptosis induction of U937 human leukemia cells by diallyl trisulfide induces through generation of reactive oxygen species

BACKGROUND

Diallyl trisulfide (DATS) is one of the major constituents in garlic oil and has demonstrated various pharmacological activities, including antimicrobial, antihyperlipidemic, antithrombotic, and anticancer effects. However, the mechanisms of antiproliferative activity in leukemia cells are not fully understood. In this study, the apoptotic effects of DATS were investigated in human leukemia cells.

RESULTS

Results of this study indicated that treatment with DATS resulted in significantly inhibited leukemia cell growth in a concentration- and time-dependent manner by induction of apoptosis. In U937 cells, DATS-induced apoptosis was correlated with down-regulation of Bcl-2, XIAP, and cIAP-1 protein levels, cleavage of Bid proteins, activation of caspases, and collapse of mitochondrial membrane potential. The data further demonstrated that DATS increased intracellular reactive oxygen species (ROS) generation, which was attenuated by pretreatment with antioxidant N-acetyl-l-cysteine (NAC), a scavenger of ROS. In addition, administration of NAC resulted in significant inhibition of DATS-induced apoptosis by inhibiting activation of caspases.

CONCLUSIONS

The present study reveals that the cytotoxicity caused by DATS is mediated by generation of ROS and subsequent activation of the ROS-dependent caspase pathway in U937 leukemia cells.

Diallyl trisulfide as an inhibitor of benzo(a)pyrene-induced precancerous carcinogenesis in MCF-10A cells

Diallyl trisulfide (DATS) is a garlic organosulfide that is toxic to cancer cells, however, little is known about its effect in the initiation phase of carcinogenesis. We sought to determine whether DATS could inhibit the carcinogen, benzo(a)pyrene (BaP), from inducing precancerous activity, in vitro. MCF-10A cells were either pre-treated (PreTx) or concurrently treated (CoTx) with 1 μM BaP, and 6 or 60 μM DATS for up to 24h. The DATS 6 and 60 μM CoTx inhibited BaP-induced cell proliferation by an average of 71.1% and 120.8%, respectively, at 6h. The 60 μM DATS pretreatment decreased BaP-induced G2/M cell cycle transition by 127%, and reduced the increase in cells in the S-phase by 42%; whereas 60 μM DATS CoTx induced a 177% increase in cells in G1. DATS effectively inhibited (P<0.001) BaP-induced peroxide formation by at least 54%, which may have prevented the formation of BaP-induced DNA strand breaks. In this study, we reveal mechanisms involved in DATS inhibition of BaP-induced carcinogenesis, including inhibition of cell proliferation, regulation of cell cycle, attenuation of ROS formation, and inhibition of DNA damage. At the doses evaluated, DATS appears to be an effective attenuator of BaP-induced breast carcinogenesis, in vitro.

The Effect of Diallyl Polysulfanes on Cellular Signaling Cascades

Diallyl polysulfanes, such as diallyl trisulfide and diallyl tetrasulfide, are regarded as a group of potential chemopreventive compounds as they have been proven to be effective inhibitors of cancer cells. These agents have been implicated in signal transductions, including the generation of Reactive Oxygen Species (ROS), Endoplasmic Reticulum (ER) stress, mitogen-activated protein kinase (MAPK) signaling, regulation of cell cycle progression, and induction of apoptosis. Nonetheless, certain aspects of the diallyl polysulfane triggered inhibitory effects on cancer cells are still not clear. Understanding the targeted signaling pathways may help to develop new strategies to treat cancer and other diseases. This review is therefore aimed at addressing the targeting of specific intracellular signal transduction cascades by these diallyl polysulfanes in order to shed some light on possible mechanisms of action of these compounds.

Thiol, disulfide, and trisulfide complexes of Ru porphyrins: potential models for iron-sulfur bonds in heme proteins

Thirty-two Ru(porp)L(2) complexes have been synthesized, where porp = the dianion of meso-tetramesitylporphyrin (TMP) or meso-tetrakis(4-methylphenyl)porphyrin (H(2)T-pMe-PP), and L = a thiol, a sulfide, a disulfide, or a trisulfide. Species studied were with RSH [R = Me, Et, (n)Pr, (i)Pr, (t)Bu, Bn (benzyl), and Ph], RSR (R = Me, Bn), RSSR (R = Me, Et, (n)Pr, Bn) and MeSS(t)Bu, and RSSSR (R = Me, Bn). All the species except two, which were the isolated Ru(T-pMe-PP)((t)BuSH)(2) and Ru(TMP)(MeSSMe)(2), were characterized in situ. The disulfide complex was characterized by X-ray analysis. (1)H NMR data for the coordinated thiols are the first reported within metalloporphyrin systems, and are especially informative because of the upfield shifts of the axial sulfur-containing ligands due to the porphyrin π-ring current effect, which is also present in the di- and trisulfide species. The disulfide in the solid state structure of Ru(TMP)(MeSSMe)(2) is η(1)(end-on) coordinated, the first example of such bonding in a nontethered, acyclic dialkyl disulfide; (1)H-(1)H EXSY NMR data in solution show that the species undergoes 1,2-S-metallotropic shifts. Stepwise formation of the bis(disulfide) complex from Ru(TMP)(MeCN)(2) in solution occurs with a cooperativity effect, resembling behavior of Fe(II)-porphyrin systems where crystal field effects dominate, but ligand trans-effects are more likely in the Ru system. The η(1)(end-on) coordination mode is also favored for the trisulfide ligand. Discussed also are the remarkable linear correlations that exist between the ring-current shielding shifts for the axial ligand C(1) protons of Ru(porp)(RS(x)R)(2) and x (the number of S atoms). The Introduction briefly reviews literature on Ru- and Fe porphyrins (including heme proteins) with sulfur-containing ligands or substrates, and relationships between our findings and this literature are discussed throughout the paper.

Effect of diallyl trisulfide derivatives on the induction of apoptosis in human prostate cancer PC-3 cells

The effects of five derivatives of diallyl trisulfide (DATS) were investigated on apoptosis in prostate cancer PC-3 cells, including dibutenyl trisulfide (DBTS), bis(2-methylallyl) trisulfide (2-M-DATS), dipentenyl trisulfide (DPTS), bis(3-methylbut-2-enyl) trisulfide (3-M-DBTS), and dihexenyl trisulfide (DHTS). Our present study demonstrated that DATS derivatives can suppress proliferation of PC-3 cells in a dose- and time-dependent manner, and that a change in the DATS structure could have an impact on its biological activity in the following order: 2-M-DATS > DBTS ≈ DPTS ≈ DATS > 3-M-DBTS ≈ DHTS. Typical apoptotic nuclei were shown by Hoechst 33342 staining with 80 μM concentrations of DATS derivatives for 24 h. And flow cytometric analysis and DNA fragmentation assay also demonstrated that DATS derivatives induced apoptosis in PC-3 cells. Meanwhile, experimental results showed that DBTS, 2-M-DATS, and DPTS cause G2-M phase cell cycle arrest. Furthermore, a series of apoptosis-associated features were observed, which include a notable decrease in the expression of procaspases-3, up-regulation of pro-apoptotic proteins Bax expression, and down-regulation of anti-apoptotic proteins Bcl-2 expression in PC-3 cells. All of the evidences above indicate that DATS derivatives suppressed proliferation of PC-3 cells which was associated with the induction of apoptosis regulated by Bax/Bcl-2.

Molecular mechanisms and targets of cancer chemoprevention by garlic-derived bioactive compound diallyl trisulfide

Health benefits of garlic and other Allium vegetables (e.g., onions), such as lipid lowering and anticancer effects, are credited to metabolic byproducts, including diallyl trisulfide (DATS). Evidence for anticancer effects of garlic derives from both population-based case-control studies, and clinical and laboratory investigations using purified garlic constituents such as DATS. Studies have shown that DATS can offer protection against chemically-induced neoplasia as well as oncogene-driven spontaneous cancer development in experimental rodents. Mechanisms underlying cancer chemopreventive effects of DATS are not completely understood, but known pharmacological responses to this natural product include alteration in carcinogen-metabolizing enzymes, cell cycle arrest, induction of apoptotic cell death, suppression of oncogenic signal transduction pathways, and inhibition of neoangiogenesis. This article reviews mechanisms and targets of cancer chemoprevention by DATS.

Notch activation by phenethyl isothiocyanate attenuates its inhibitory effect on prostate cancer cell migration

Phenethyl isothiocyanate (PEITC) is a promising cancer chemopreventive component of edible cruciferous vegetables with in vivo efficacy against prostate cancer in experimental rodents. Cancer chemopreventive response to PEITC is characterized by its ability to inhibit multiple oncogenic signaling pathways, including nuclear factor-κB, Akt, and androgen receptor. The present study demonstrates, for the first time, that PEITC treatment activates Notch signaling in malignant as well as normal human prostate cells. Exposure of human prostate cancer cells (LNCaP, PC-3, and DU145) and a normal human prostate epithelial cell line (PrEC) to PEITC resulted in cleavage (active form) of Notch1 and Notch2, and increased transcriptional activity of Notch. In PC-3 and LNCaP cells, PEITC treatment caused induction of Notch ligands Jagged1 and Jagged2 (PC-3), overexpression of γ-secretase complex components Presenilin1 and Nicastrin (PC-3), nuclear enrichment of cleaved Notch2, and/or up-regulation of Notch1, Notch2, Jagged1, and/or Jagged2 mRNA. PEITC-induced apoptosis in LNCaP and PC-3 cells was significantly attenuated by RNA interference of Notch2, but not by pharmacological inhibition of Notch1. Inhibition of PC-3 and LNCaP cell migration resulting from PEITC exposure was significantly augmented by knockdown of Notch2 protein as well as pharmacological inhibition of Notch1 activation. Nuclear expression of cleaved Notch2 protein was significantly higher in PC-3 xenografts from PEITC-treated mice and dorsolateral prostates from PEITC-fed TRAMP mice compared with respective control. Because Notch signaling is implicated in epithelial-mesenchymal transition and metastasis, the present study suggests that anti-metastatic effect of PEITC may be augmented by a combination regimen involving a Notch inhibitor.

Hormetics: dietary triggers of an adaptive stress response

A series of dietary ingredients and metabolites are able to induce an adaptive stress response either by generation of reactive oxygen species (ROS) and/or via activation of the Nrf2/Keap1 stress response network. Most of the molecules belong to activated Michael acceptors, electrophiles capable to S-alkylate redox sensitive cysteine thiols. This review summarizes recent advances in the (re)search of these compounds and classifies them into distinct groups. More than 60 molecules are described that induce the Nrf2 network, most of them found in our daily diet. Although known as typical antioxidants, a closer look reveals that these molecules induce an initial mitochondrial or cytosolic ROS formation and thereby trigger an adaptive stress response and hormesis, respectively. This, however, leads to higher levels of intracellular glutathione and increased expression levels of antioxidant enzymes such as glutathione peroxidase, thioredoxin reductase, and superoxide dismutase. According to this principle, the author suggests the term hormetics to describe these indirect antioxidants.

Role of Bim in diallyl trisulfide-induced cytotoxicity in human cancer cells

The aim of this study was to investigate the effect of garlic constituent diallyl trisulfide (DATS) on the cell-death signaling pathway in a human breast cell line (MDA-MB-231). We observed that DATS (10-100 µM) treatment resulted in dose- and time-dependent cytotoxicity. Treatment of MDA-MB-231 cells with a cytotoxicity inducing concentration of DATS (50-80 µM) resulted in an increase in the intracellular level of reactive oxygen species (ROS). Data from assay with MitoSOX(TM) Red reagent suggest that mitochondria are the main source of ROS generation during DATS treatment. DATS-induced oxidative stress was detected through glutaredoxin (GRX), a redox-sensing molecule, and subsequently GRX was dissociated from apoptosis signal-regulating kinase 1 (ASK1). Dissociation of GRX from ASK1 resulted in the activation of ASK1. ASK1 activated a downstream signal transduction JNK (c-Jun N-terminal kinase)-Bim pathway. SP600125, a JNK inhibitor, inhibited DATS-induced Bim phosphorylation and protected cells from DATS-induced cytotoxicity. Our results indicate that the cytotoxicity caused by DATS is mediated by the generation of ROS and subsequent activation of the ASK1-JNK-Bim signal transduction pathway in human breast carcinoma MDA-MB-231 cells.

S-allylmercaptocysteine effectively inhibits the proliferation of colorectal cancer cells under in vitro and in vivo conditions

S-allylmercaptocysteine (SAMC), one of the water-soluble organosulfur garlic derivatives, has been demonstrated as a suppressive agent against some tumors. The effects of SAMC on the proliferation and metastasis of colorectal cancer (CRC) under in vitro and in vivo conditions were evaluated here. The viabilities and migrations of CRC cells SW480, SW620, Caco-2 treated with SAMC were measured by MTT, scratch-wound, and transwell assays. The in vivo anticancer effect of SAMC against luciferase-expressing SW620 xenografts in mice was determined by bioluminescence imaging and histopathology observation. The apoptosis of SAMC-treated CRC cells was examined by Western blotting. The results demonstrate that SAMC could effectively suppress the growth and metastasis of colorectal cancer cells both in vivo and in vitro. The anticancer effect of SAMC was related to the decreased proliferation and increased apoptosis as well as necrosis of cancer cells. Oral administration of SAMC in the quantity/concentration used had no apparent toxic side effect on the vital organs of the experimental mice. Taken together, the proliferation and metastasis of CRC cells can be significantly suppressed by SAMC treatment under both in vitro and in vivo conditions. SAMC may thus be a promising candidate for CRC chemotherapy.

Diallyl trisulfide (DATS) inhibits mouse colon tumor in mouse CT-26 cells allograft model in vivo

Our earlier studies showed that DATS induced apoptosis in human colon cancer HT29 and colo 205 cell lines in vitro. However, there is no report to show that DATS induced apoptosis in vitro and inhibited CT26 cancer cells in vivo on a murine allograft animal model. In vitro studies, the results indicated that DATS induced morphological changes and induction of apoptosis in CT26 cells. In vivo studies, CT26 cancer cells were implanted into BALB/c mice and groups of mice were treated with vehicle, DATS (10 and 50 mg/kg of body weight). DATS were injected once per four days intraperitoneally (i.p.), with treatment starting 4 weeks prior to cells inoculation. Treatment with vehicle or with 10 and 50 mg/kg of DATS resulted in a reduction in tumor volume and weight. Tumor volume and total hemoglobin in allograft mice treated with 50 mg/kg DATS were significantly smaller than that in the control group. These findings indicated that DATS inhibits tumor growth in an allograft animal model. Thus, DATS may represent a colon cancer preventive agent and can be used in the future.