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

The potential of diallyl trisulfide for cancer prevention and treatment, with mechanism insights

Cancer has become an important public health problem worldwide, and there is currently a lack of effective treatment and prevention strategies. Natural plant active ingredients have been proven to be a safe and highly promising method for preventing and treating cancer. It has been found that diallyl trisulfide have anticancer effects in multiple types of cancer via inhibiting cancer proliferation, enhancing chemotherapy sensitivity, inducing apoptosis/autophagy, suppressing invasion/migration, regulating microenvironment. With the deepening of research on new strategies for cancer prevention and treatment, the role of diallyl trisulfides in cancers occurrence, prognosis, and drug resistance is also receiving increasing attention. In order to better understand the relationship between diallyl trisulfides and various cancer, as well as the role and mechanism of diallyl trisulfides in cancer prevention and treatment, we briefly summarized the role and function of diallyl trisulfide in cancers.

USP3 promotes osteosarcoma progression via deubiquitinating EPHA2 and activating the PI3K/AKT signaling pathway

Ubiquitin-specific protease 3 (USP3) plays an important role in the progression of various tumors. However, the role of USP3 in osteosarcoma (OS) remains poorly understood. The aim of this study was to explore the biological function of USP3 in OS and the underlying molecular mechanism. We found that OS had higher USP3 expression compared with that of normal bone tissue, and high expression of USP3 was associated with poor prognosis in patients with OS. Overexpression of USP3 significantly increased OS cell proliferation, migration, and invasion. Mechanistically, USP3 led to the activation of the PI3K/AKT signaling pathway in OS by binding to EPHA2 and then reducing its protein degradation. Notably, the truncation mutant USP3-F2 (159-520) interacted with EPHA2, and amino acid 203 was found to play an important role in this process. And knockdown of EPHA2 expression reversed the pro-tumour effects of USP3-upregulating. Thus, our study indicates the USP3/EPHA2 axis may be a novel potential target for OS treatment.

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.

Molecular Mechanism of Natural Food Antioxidants to Regulate ROS in Treating Cancer: A Review

Cancer is the second-highest mortality rate disease worldwide, and it has been estimated that cancer will increase by up to 20 million cases yearly by 2030. There are various options of treatment for cancer, including surgery, radiotherapy, and chemotherapy. All of these options have damaging adverse effects that can reduce the patient's quality of life. Cancer itself arises from a series of mutations in normal cells that generate the ability to divide uncontrollably. This cell mutation can happen as a result of DNA damage induced by the high concentration of ROS in normal cells. High levels of reactive oxygen species (ROS) can cause oxidative stress, which can initiate cancer cell proliferation. On the other hand, the cytotoxic effect from elevated ROS levels can be utilized as anticancer therapy. Some bioactive compounds from natural foods such as fruit, vegetables, herbs, honey, and many more have been identified as a promising source of natural antioxidants that can prevent oxidative stress by regulating the level of ROS in the body. In this review, we have highlighted and discussed the benefits of various natural antioxidant compounds from natural foods that can regulate reactive oxygen species through various pathways.

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.

Protective Effect of Fucoxanthin on Zearalenone-Induced Hepatic Damage through Nrf2 Mediated by PI3K/AKT Signaling

Hepatotoxic contaminants such as zearalenone (ZEA) are widely present in foods. Marine algae have a wide range of potential applications in pharmaceuticals, cosmetics, and food products. Research is ongoing to develop treatments and products based on the compounds found in algae. Fucoxanthin (FXN) is a brown-algae-derived dietary compound that is reported to prevent hepatotoxicity caused by ZEA. This compound has multiple biological functions, including anti-diabetic, anti-obesity, anti-microbial, and anti-cancer properties. Furthermore, FXN is a powerful antioxidant. In this study, we examined the effects of FXN on ZEA-induced stress and inflammation in HepG2 cells. MTT assays, ROS generation assays, Western blots, and apoptosis analysis were used to evaluate the effects of FXN on ZEA-induced HepG2 cell inflammation. Pre-incubation with FXN reduced the cytotoxicity of ZEA toward HepG2 cells. FXN inhibited the ZEA-induced production of pro-inflammatory cytokines, including IL-1 β, IL-6, and TNF-α. Moreover, FXN increased HO-1 expression in HepG2 by activating the PI3K/AKT/NRF2 signaling pathway. In conclusion, FXN inhibits ZEA-induced inflammation and oxidative stress in hepatocytes by targeting Nrf2 via activating PI3K/AKT signaling.

Involvement of adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper 1 in diallyl trisulfide-induced cytotoxicity in hepatocellular carcinoma cells

It has been demonstrated that APPL1 (adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper 1) is involved in the regulation of several growth-related signaling pathways and thus closely associated with the development and progression of some cancers. Diallyl trisulfide (DAT), a garlic-derived bioactive compound, exerts selective cytotoxicity to various human cancer cells through interfering with pro-survival signaling pathways. However, whether and how DAT affects survival of human hepatocellular carcinoma (HCC) cells remain unclear. Herein, we tested the hypothesis of the involvement of APPL1 in DAT-induced cytotoxicity in HCC HepG2 cells. We found that Lys 63 (K63)-linked polyubiquitination of APPL1 was significantly decreased whereas phosphorylation of APPL1 at serine residues remained unchanged in DAT-treated HepG2 cells. Compared with wild-type APPL1, overexpression of APPL1 K63R mutant dramatically increased cell apoptosis and mitigated cell survival, along with a reduction of phosphorylation of STAT3, Akt, and Erk1/2. In addition, DAT administration markedly reduced protein levels of intracellular TNF receptor-associated factor 6 (TRAF6). Genetic inhibition of TRAF6 decreased K63-linked polyubiquitination of APPL1. Moreover, the cytotoxicity impacts of DAT on HepG2 cells were greatly attenuated by overexpression of wild-type APPL1. Taken together, these results suggest that APPL1 polyubiquitination probably mediates the inhibitory effects of DAT on survival of HepG2 cells by modulating STAT3, Akt, and Erk1/2 pathways.

Insight into drug sensitizing effect of diallyl disulfide and diallyl trisulfide from Allium sativum L. on paclitaxel-resistant triple-negative breast cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Ayurvedic practitioners and herbal healers in India and China have extensively used garlic (Allium sativum L.) to treat cancers. Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are major volatile organosulfur phytochemical constituents found in garlic.

AIM OF THE STUDY

To find new insight into the drug sensitizing effect of DADS and DATS on paclitaxel (PTX)-resistant triple-negative breast cancer cells (TNBC/PR).

MATERIALS AND METHODS

This study estimates the non-toxic concentration of DADS and DATS against normal healthy breast epithelial cell line (MCF-12A) by using a trypan blue viability assay. Also, it evaluates the effect of DADS and DATS on the sensitization of established stable TNBC/PR cell clones (MDA-MB 231 PR and MDA-MB 468 PR) by MTT, BrdU incorporation, intracellular ROS, cell cycle, and apoptosis assays.

RESULTS

The results show that DADS and DATS are non-cytotoxicity against MCF-12A cells. Nevertheless, DADS and DATS have shown significantly high cytotoxicity against MDA-MB 231 PR and MDA-MB 468 PR cells. They also inhibited PTX-resistant cell proliferation by blocking the cell cycle. Further, they induced apoptosis by activation of caspase 3 and 9. N-acetyl cysteine pre-treatment inhibited DADS and DATS-induced intracellular ROS release. In silico study shows that DADS and DATS interact with a large extracellular loop (LEL) of CD151 with a binding energy of -4.0 kcal/mol and transmembrane domain (TM) with a binding affinity of 11.7 and 13.6 kcal/mol, respectively. They also inhibited the surface expression of CD151 in TNBC/PR cells.

CONCLUSION

This study implies that DADS and DATS could be considered for sensitizing drug-resistant breast cancers.

Endogenous and exogenous hydrogen sulfide modulates urothelial bladder carcinoma development in human cell lines

The role of H₂S in urothelial carcinoma (UC) is still unclear. Here we have evaluated the expression of H₂S producing enzymes as well as the effect of endogenous and exogenous H₂S on human bladder UC cells. In human UC cells the expression of cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3-MST); is significantly lower as compared to healthy cells. A modulatory role for the H₂S pathway is supported by the finding that, the overexpression of CSE or CBS, but not 3-MST, inhibits cell proliferation and promotes apoptosis. A similar effect is obtained by using exogenous H₂S. Diallyl trisulfide (DATS), which is a fully characterized H₂S donor, inhibits the proliferation of UC cells in a time and concentration-dependent manner as well as promotes apoptosis. Moreover, DATS also induces autophagy, as determined by transcriptomic and western blot analysis. Finally, DATS inhibits mRNA expression levels of canonical markers of epithelial-mesenchymal transition by limiting migration and clonogenic ability of human UC cells in vitro. In conclusion, in urothelial carcinoma, there is an impairment of H₂S pathway that involves CSE and CBS- derived hydrogen sulfide. Thus, targeting H₂S signaling pathway in urothelial carcinoma could represent a novel therapeutic strategy.

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.

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.

Diallyl thiosulfinate enhanced the anti-cancer activity of dexamethasone in the side population cells of multiple myeloma by promoting miR-127-3p and deactivating the PI3K/AKT signaling pathway

Background

Side population (SP) cells, which have similar features to those of cancer stem cells, show resistance to dexamethasone (Dex) treatment. Thus, new drugs that can be used in combination with Dex to reduce the population of SP cells in multiple myeloma (MM) are required. Diallyl thiosulfinate (DATS, allicin), a natural organosulfur compound derived from garlic, has been shown to inhibit the proliferation of SP cells in MM cell lines. Therefore, we investigated the effect of a combination of DATS and Dex (DAT + Dex) on MM SP cells.

Methods

SP cells were sorted from MM RPMI-8226 and NCI-H929 cell lines using Hoechst 33342-labeled fluorescence-activated cell sorting. The growth of SP cells was evaluated using the cell counting kit-8 assay. Cell cycle and apoptosis assays were conducted using a BD Calibur flow cytometer. miRNA expression was measured using quantitative reverse transcription-polymerase chain reaction. Phosphoinositide 3-kinase (PI3K), phosphorylated AKT (p-AKT), AKT, p-mechanistic target of rapamycin (mTOR), and mTOR levels were measured using western blot analysis.

Results

Our results showed that the combination of DATS+Dex inhibited sphere formation, colony formation, and proliferation of MM SP cells by inducing apoptosis and cell cycle arrest in the G1/S phase. In addition, the combination of DATS+Dex promoted miR-127-3p expression and inhibited PI3K, p-AKT, and p-mTOR expression in SP cells. Knockdown of miR-127-3p expression weakened the effect of DATS+Dex on cell proliferation, colony formation, apoptosis, and cell cycle of MM SP cells. Additionally, knockdown of miR-127-3p activated the PI3K/AKT/mTOR signaling pathway in MM SP cells cotreated with DATS+Dex.

Conclusion

We demonstrated that cotreatment with DATS+Dex reduced cell proliferation, promoted apoptosis, and caused cell cycle arrest of MM SP cells by promoting miR-127-3p expression and deactivating the PI3K/AKT/mTOR signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-07833-5.

Role of hydrogen sulfide donors in cancer development and progression

In recent years, a vast number of potential cancer therapeutic targets have emerged. However, developing efficient and effective drugs for the targets is of major concern. Hydrogen sulfide (H2S), one of the three known gasotransmitters, is involved in the regulation of various cellular activities such as autophagy, apoptosis, migration, and proliferation. Low production of H2S has been identified in numerous cancer types. Treating cancer cells with H2S donors is the common experimental technique used to improve H2S levels; however, the outcome depends on the concentration/dose, time, cell type, and sometimes the drug used. Both natural and synthesized donors are available for this purpose, although their effects vary independently ranging from strong cancer suppressors to promoters. Nonetheless, numerous signaling pathways have been reported to be altered following the treatments with H2S donors which suggest their potential in cancer treatment. This review will analyze the potential of H2S donors in cancer therapy by summarizing key cellular processes and mechanisms involved.

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.

Functional Application of Sulfur-Containing Spice Compounds

Sulfur-containing spice compounds possess diverse biological functions and play an important role in food, chemicals, pharmaceuticals, and agriculture. The development of functional spices has become increasingly popular, especially for medicinal functions for dietary health. Thus, this review focuses on the properties and functions of sulfur-containing spice compounds, including antioxidant, anti-inflammatory, antiobesity, anticancer, antibacterial, and insecticidal functions, among others. Developments over the last five years concerning the properties of sulfur-containing spice compounds are summarized and discussed.

Triggering of Apoptosis in Osteosarcoma 143B Cell Line by Carbon Quantum Dots via the Mitochondrial Apoptotic Signal Pathway

Objectives

Carbon-based nanomaterials have gained attention in the field of biomedicine in recent years, especially for the treatment of complicated diseases such as cancer. Here, we report a novel carbon-based nanomaterial, named carbon quantum dots (CQDs), which has potential for cancer therapy. We performed a systematic study on the effects of CQDs on the osteosarcoma 143B cell line in vitro and in vivo.

Methods

Cell counting assay, the neutral red assay, lactic dehydrogenase assay, and fluorescein isothiocyanate (FITC) Annexin V/Propidium iodide (PI) were used to detect the cytotoxicity and apoptosis of CQDs on the 143B cell line. Intracellular reactive oxygen species (ROS) were detected by the oxidation-sensitive fluorescent probe 2′,7′-dichlorofluorescein diacetate. The JC-10 assay was used to detect the mitochondrial membrane potential (MMP) of 143B cells incubated with CQDs. The effects of CQDs on the 143B cell line were evaluated by Western blot and immunofluorescence analysis of apoptosis-related proteins Bax, Bcl-2, cytochrome-C, caspase-3, cleaved-caspase-3, PARP1, and cleaved-PARP1. Male tumor-bearing BALB/c nude mice were used to investigate the antitumor effects of CQDs, and the biosafety of CQDs in vivo was tested in male BALB/c mice by measuring weight changes, hematology tests, and histological analyses of major organs.

Results

CQDs exhibited a high cytotoxicity and induced apoptosis toward the 143B cell line. CQDs can also significantly increase the intracellular level of ROS and lower the mitochondrial membrane potential levels of 143B cells. CQDs increase apoptotic protein expression to induce apoptosis of 143B cells by triggering the mitochondrial apoptotic signaling pathway. The tumor volume in the CQD-treated mice was smaller than that in the control group, the tumor volume inhibition rate was 38.9%, and the inhibitory rate by tumor weight was 30.1%. All biosafety test indexes were within reference ranges, and neither necrosis nor inflammation was observed in major organs.

Conclusions

CQDs induced cytotoxicity in the 143B cell line through the mitochondrial apoptotic signaling pathway. CQDs not only showed an antitumor effect but also high biocompatibility in vivo. As a new carbon-based nanomaterial, CQDs usage is a promising method for novel cancer treatments.

Piperlongumine induces apoptosis and G2/M phase arrest in human osteosarcoma cells by regulating ROS/PI3K/Akt pathway

Previous research has reported that piperlongumine exerts antitumor properties on several types of tumor cells. However, its effect on osteosarcoma cells remains unknown. This study aimed to investigate the antitumor effects of piperlongumine on osteosarcoma cells (MG63 and U2OS cells) in vitro and determined the underlying mechanism. Cell viability was measured using MTT assay. Cell apoptosis was assessed via AO/EB staining and flow cytometry apoptosis as well as western blot analysis. Cell cycle distribution was detected by flow cytometric cell cycle and western blot analysis. In our research, we found that piperlongumine induced apoptosis and G2/M phase arrest of MG63 cells. Western blot analysis not only confirmed the above results, but also demonstrated that piperlongumine induced apoptosis of osteosarcoma cells by activating Caspase-9-dependent apoptotic pathway. Furthermore, we also found that piperlongumine significantly induced apoptosis and cell cycle arrest of osteosarcoma cells by regulating ROS/PI3K/Akt signaling pathway. In summary, our findings suggested that piperlongumine inhibited osteosarcoma progression by promoting apoptosis of osteosarcoma cells. In addition, the underlying mechanism demonstrated that piperlongumine produced potent antitumor properties in osteosarcoma cells by regulating ROS/PI3K/Akt signaling pathway.

Low-Frequency Magnetic Fields (LF-MFs) Inhibit Proliferation by Triggering Apoptosis and Altering Cell Cycle Distribution in Breast Cancer Cells

Breast cancer is a common malignancy threatening women’s health around the world. Despite improved treatments for different subtypes of breast tumors that have been put forward, there still exists a poor therapeutic response and prognosis. Magnetic fields, as a non-invasive therapy, have shown anti-tumor effects in vitro and in vivo; however, the detailed mechanisms involved are still not clear. In this study, we found that in exposure to low-frequency magnetic fields (LF-MFs) with an intensity of 1 mT and frequencies of 50, 125, 200, and 275 Hz, separately, the proliferation of breast cancer cells was inhibited and LF-MF with 200 Hz reached the optimum inhibition effect, on exposure time-dependently. Notably, we found that exposure to LF-MF led to MCF-7 and ZR-75-1 cell apoptosis and cell cycle arrest. Moreover, we also discovered that LF-MF effectively increased the level of reactive oxygen species (ROS), suppressed the PI3K/AKT signaling pathway, and activated glycogen synthase kinase-3β (GSK-3β). We demonstrated that the GSK3β activity contributed to LF-MF-induced cell proliferation inhibition and apoptosis, while the underlying mechanism was associated with the inhibition of PI3K/AKT through increasing the intracellular ROS accumulation. These results indicate that LF-MF with a specific frequency may be an attractive therapy to treat breast cancers.

Diallyl trisulfide attenuates hyperglycemia-induced endothelial apoptosis by inhibition of Drp1-mediated mitochondrial fission

AIMS

Hyperglycemia induces endothelial cell apoptosis and blood vessel damage, while diallyl trisulfide (DATS) has shown cardiovascular protection in animal models and humans. The aim of this study was to investigate the effects of DATS on inhibition of high glucose-induced endothelial cell apoptosis and the underlying molecular events.

METHODS

Human umbilical vein endothelial cells (HUVECs) were incubated with DATS (100 μM) for 30 min and then cultured in high-glucose medium (HG, 33 mM) for 24 h for assessment of apoptosis, glutathione (GSH), reactive oxygen species (ROS), superoxide dismutase (SOD), and gene expression using the terminal deoxyuridine triphosphate nick end labeling (TUNEL), flow cytometry, caspase-3 activity, ROS, SOD, and western blot assays as well as JC-1 and MitoTracker Red staining, respectively.

RESULTS

DATS treatment significantly inhibited high glucose-induced HUVEC apoptosis by blockage of intracellular and mitochondrial ROS generation, maintenance of the mitochondrial membrane potential, and suppression of high glucose-induced dynamin-related protein 1 (Drp1) expression. Furthermore, DATS blockage of high glucose-induced mitochondrial fission and apoptosis was through adenosine monophosphate-activated protein kinase (AMPK) activation-inhibited Drp1 expression in HUVECs.

CONCLUSIONS

DATS demonstrated the ability to inhibit high glucose-induced HUVEC apoptosis via suppression of Drp1-mediated mitochondrial fission in an AMPK-dependent fashion.

microRNA-378a Regulates the Reactive Oxygen Species (ROS)/Phosphatidylinositol 3-Kinases (PI3K)/AKT Signaling Pathway in Human Lens Epithelial Cells and Cataract

BACKGROUND Cataract is associated with increased apoptosis of the epithelial cells of the ocular lens. Previous studies have shown that microRNA-378a (miR-378a) has a role in the development of cataract, but the molecular mechanisms remain unclear. This study aimed to investigate the effects of miR-378a in human lens epithelial cells (HLECs) in vitro and normal lens tissues and cataract tissues. MATERIAL AND METHODS HLECs were grown in culture. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blot were used to examine gene expression levels. The MTT and TUNEL assay measured cell growth and apoptosis. Changes in the fluorescence ratio of ethidium to dihydroethidium (E: DHE) and in 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate (C-H₂DCFDA) were used to detect superoxide (O₂⁻) and hydrogen peroxide (H₂O₂). The expression levels of miR-378a and the superoxide dismutase 1 gene (SOD1) were measured in normal human lens tissues and cataract tissues. RESULTS Upregulation of miR-378a reduced the expression of SOD1. Levels of O₂⁻ were upregulated and H₂O₂ was slightly down-regulated by miR-378a. The use of a miR-378a mimic suppressed cell growth and enhanced apoptosis of HLECs, which were reversed by the use of a miR-378a inhibitor. SOD1 overexpression rescued the miR-378a-induced phenotypes of HLEC cells. Treatment with the PI3K inhibitor, LY294002, reversed miR-378a and ROS-regulated proliferation and apoptosis of HLEC cells. Also, miR-378a was upregulated, and SOD1 was down-regulated in human cataract tissues. CONCLUSIONS In HLECs, expression of miR-378a regulated ROS and PI3K/AKT signaling, and miR-378a was upregulated, and SOD1 was down-regulated in human cataract tissue.

Increased Sulfiredoxin Expression in Gastric Cancer Cells May Be a Molecular Target of the Anticancer Component Diallyl Trisulfide

Sulfiredoxin (Srx) is a newly discovered antioxidant enzyme playing a role in the catalytic reduction of oxidative modifications. Srx is overexpressed in a variety of cancers. It may promote carcinogenesis as well as tumor progression. In this study, we report for the first time that Srx expression might be positively associated with the development of gastric cancer and tumor malignancy. Immunohistochemistry showed that, compared to normal tissues (42%, 20/47), Srx expression in gastric tumors (85%, 40/47) was much more common (chi-square test, p<0.01). In addition, the staining of Srx was stronger in poorly differentiated gastric cancer than in well-differentiated gastric cancer. Western blotting showed that, in the gastric tumor cell line BGC823, the Srx protein was upregulated in response to H₂O₂ treatment, although it was inadequate to counteract the increased oxidative stress, as indicated by the gradually increasing level of malondialdehyde (MDA). In addition, Srx expression, MDA levels, and ROS levels in BGC823 cells were markedly inhibited upon treatment with diallyl trisulfide (DATS), a major constituent of garlic oil with proven anticancer effects. These results suggest that Srx may be an oxidative stress marker. Antioxidation may account for the anticancer potential of garlic.

Neuroprotection through flavonoid: Enhancement of the glyoxalase pathway

The glyoxalase pathway functions to detoxify reactive dicarbonyl compounds, most importantly methylglyoxal. The glyoxalase pathway is an antioxidant defense mechanism that is essential for neuroprotection. Excessive concentrations of methylglyoxal have deleterious effects on cells, leading to increased levels of inflammation and oxidative stress. Neurodegenerative diseases - including Alzheimer's, Parkinson's, Aging and Autism Spectrum Disorder - are often induced or exacerbated by accumulation of methylglyoxal. Antioxidant compounds possess several distinct mechanisms that enhance the glyoxalase pathway and function as neuroprotectants. Flavonoids are well-researched secondary plant metabolites that appear to be effective in reducing levels of oxidative stress and inflammation in neural cells. Novel flavonoids could be designed, synthesized and tested to protect against neurodegenerative diseases through regulating the glyoxalase pathway.

JTC-801 exerts anti-proliferative effects in human osteosarcoma cells by inducing apoptosis

BACKGROUND

The research of G protein-coupled receptors (GPCRs) is a promising strategy for drug discovery. In cancer therapy, there is a need to discover novel agents that can inhibit proliferation and induce apoptosis in cancer cells. JTC-801 is a novel GPCR antagonist with the function of reversing pain and anxiety symptoms. This study aims to investigate the antitumor effects of JTC-801 on human osteosarcoma cells (U2OS) and elucidate the underlying mechanism.

MATERIALS AND METHODS

The Cell Counting Kit-8 assay was used to detect the viability of U2OS cells treated with JTC-801 in vitro. The cell apoptosis was evaluated using a flow cytometry assay with Annexin V-FITC/PI double staining. The inhibitory effect of JTC-801 on invasion and migration of U2OS cells were determined by the Transwell assays. Western blot assay was performed to measure the levels of proteins related to cell apoptosis and its mechanism.

RESULTS

The JTC-801 significantly decreased the viability of U2OS cells (p < .05) as a result of its anti-proliferative effect through induction of apoptosis associated with activation of BAX, Caspase-3 and down-regulating BCL-2 expression. The invasive and migratory cells were obviously reduced after JTC-801 treatment (p < .05). Further, the phosphorylated AKT, mTOR and active p70 S6 protein kinase in the PI3K/AKT signaling pathway were obviously lessened in the JTC-801 treated U2OS group (p < .05).

CONCLUSIONS

JTC-801 may exert osteosarcoma cell growth inhibition by promoting cell apoptosis, through PI3K/AKT signaling pathway participation.

SLC34A2 Regulates the Proliferation, Migration, and Invasion of Human Osteosarcoma Cells Through PTEN/PI3K/AKT Signaling

Osteosarcoma (OS) is a bone malignancy with high incidence. The underlying molecular mechanisms that are associated with the development of OS need further investigation. In this study, we showed that SLC34A2, a member of the solute carrier gene family, was significantly downregulated in OS patients and cell lines. Overexpression of SLC34A2 inhibited the proliferation, migration, and invasion of OS cells. Mechanistically, we found that SLC34A2 interacted with PTEN, and inactivated the PI3K/AKT signaling pathway. Collectively, our results demonstrated that SLC34A2 plays important roles in regulating the cancer cell growth of OS. The downregulation of SLC34A2 in OS patients suggested that it might be a promising target in the diagnosis and therapy of OS.

Diallyl trisulfide induces apoptosis and mitotic arrest in AGS human gastric carcinoma cells through reactive oxygen species-mediated activation of AMP-activated protein kinase

Diallyl trisulfide (DATS), one of the principal constituents of garlic oil, is a kind of organosulfur compound with high anti-cancer activity. Although inhibition of cancer cell proliferation by DATS is known to be associated with the induction of apoptosis and cell cycle arrest related to reactive oxygen species (ROS) production, it is still necessary to study the detailed mechanisms. In this study, we investigated the role of ROS on the activation of AMP-activated protein kinase (AMPK) in DATS-induced apoptosis and cell cycle arrest in AGS human gastric carcinoma cells. The results of the present study indicate that DATS inhibited proliferation of AGS cells by promoting apoptosis, and accumulating cellular portion of G2/M phase via the induction of cyclin B1 and cyclin-dependent kinase p21(WAF1/CIP1). The phosphorylation of histone H3 was also markedly increased following treatment with DATS, revealing that DATS stimulated a mitotic arrest, not the G2 phase. Furthermore, we found that DATS concurrently induced phosphorylation of AMPK; however, chemical inhibition of AMPK by compound C, an AMPK inhibitor, significantly blocked apoptosis induced by DATS, suggesting that DATS induces cytotoxicity of AGS cells through the AMPK-dependent pathway. Moreover, DATS provoked intracellular ROS generation and the loss of mitochondrial membrane potential, and in particular, when ROS production was blocked by antioxidant N-acety-l-cysteine, both AMPK activation and growth inhibition by DATS were completely abolished. Collectively, these findings suggest that DATS inhibited growth of AGS cells, which was mediated by complex interplay between cellular mechanisms governing redox homeostasis, apoptosis, and cell cycle arrest, through a ROS-dependent activation of AMPK pathway.

Pterostilbene inhibits hepatocellular carcinoma through p53/SOD2/ROS-mediated mitochondrial apoptosis

Hepatocellular carcinoma (HCC) is one of the most common malignancies and the second cause of cancer-related deaths around the world. Pterostilbene (PTE), is a natural analog of resveratrol, possessing diverse pharmacological activities. In the present study, we aimed to examine the effect of PTE on tumor growth in mouse models of HCC and to elucidate the possible molecular mechanism in vivo and in vitro. We showed that PTE dose-dependently suppressed tumor growth in mice induced by diethylnitrosamine plus carbon tetrachloride, as evidenced by a decrease in the number of tumors and in the maximum size of the tumors. PTE concentration-dependently inhibited cell viability and proliferation in HepG2 cells. PTE increased caspase-3 activities and apoptosis in liver tumor tissues and cells, indicating the activation of the mitochondrial apoptotic pathway. PFTα, superoxide dismutase 2 (SOD2) lentivirus and N-acetylcysteine (NAC) significantly inhibited PTE-induced inhibition of tumor growth and cell proliferation and increase in apoptosis. PTE dose-dependently increased reactive oxygen species (ROS) levels both in liver tumor tissues and cells, which were inhibited by PFTα, SOD2 lentivirus and NAC. PTE resulted in a significant decrease in SOD2 expression in liver tumor tissues and cells, which were inhibited by PFTα, but not NAC, indicating that PTE-induced ROS generation was attributed to p53-mediated downregulation of SOD2. Collectively, PTE increased p53 expression, decreased SOD2 expression, and resulted in an increase in the ROS levels and the activation of the mitochondrial apoptotic pathway, leading to inhibition of tumor growth and cell proliferation. These data demonstrated that the p53/SOD2/ROS pathway is critical for PTE-mediated inhibition of tumor growth and HCC cell proliferation.