Apoptosis as a Mechanism of the Cancer Chemopreventive Activity of Glucosinolates: a Review

Yiqi Yangjing recipe stimulates apoptosis while suppressing the energy metabolism via under-expression of PFKFB3 in A549 cells

Background

Lung cancer is a malignant tumor associated with high morbidity and mortality. Yiqi Yangjing recipe (YYR) is a formula of traditional Chinese medicine (TCM) that is commonly used for the treatment of lung cancer with good clinical efficacy. The specific anti-cancer mechanism of YYR is still unknown. We need to embark on a more in-depth pharmacological study of YYR to determine the complex compound ingredients, which could be promoted in clinical practice to achieve efficacy in prolonging recurrent metastasis of lung cancer.

Methods

The cytotoxic effects of YYR on A549 cells were evaluated by Cell Counting Kit-8 (CCK-8) assay. The PFKFB3-under-expressed and overexpressed A549 cell lines were constructed via PFK15 treatment and transfection, respectively. The effects of YYR on PFKFB3 messenger RNA (mRNA) and protein expression were detected by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot. The pro-apoptotic and anti-glycolytic abilities of YYR were measured using flow cytometry assay and hippocampal XF96 extracellular flux analyzer. An in vivo tumorigenicity assay was performed on nude mice to confirm the anti-cancer effects of YYR.

Results

YYR has a noticeable cytotoxic activity on A549 cells, with the treatment with both YYR and PFK15 significantly inducing apoptosis. YYR and PFK15 treatment reduced the extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) in A549 cells. Similar to PFK15, YYR can down-regulate PFKFB3 expression, and PFKFB3 overexpression suppressed the apoptosis, which was reversed by YYR. Animal experiments confirmed that YYR was able to inhibit tumor growth, induce tumor cell apoptosis, and down-regulate PFKFB3 in tumor tissues.

Conclusions

This study demonstrated that YYR promoted lung cancer cell apoptosis and inhibited energy metabolism by targeting PFKFB3. Furthermore, we believe that YYR may be a suitable supplement or alternative drug for lung cancer treatment.

Evaluation of the Biological Activity of Glucosinolates and Their Enzymolysis Products Obtained from Lepidium meyenii Walp. (Maca)

Glucosinolates (GLS) were extracted and purified from Lepidium meyenii (Maca) root. Purified GLS were analyzed without desulfation by UPLC-ESI-MS. Glucosinolates were decomposed into benzyl isothiocyanate (BITC) by thioglucosidase. DPPH radical scavenging activity, ABTS radical scavenging activity, and reducing power were used to evaluate antioxidant activity of Maca crude extract (MCE), total GLS, and BITC. Maca crude extract showed the highest antioxidant activity among them, and BITC showed no antioxidant activity at concentrations less than 10 mg/mL. Cytotoxicity on five human cancer cell lines and the inhibition rate of NO production were used to evaluate the activity of anti-cancer and anti-inflammatory of total GLS and BITC. The inhibition rate of NO production of 50 μg/mL BITC can reach 99.26% and the cell viability of 100 μg/mL BITC on five tumor cell lines is less than 3%. The results show that BITC may be used as a promising anti-cancer and anti-inflammatory drug.

C. spinosa L. subsp. rupestris Phytochemical Profile and Effect on Oxidative Stress in Normal and Cancer Cells

Spices, widely used to improve the sensory characteristics of food, contain several bioactive compounds as well, including polyphenols, carotenoids, and glucosynolates. Acting through multiple pathways, these bioactive molecules affect a wide variety of cellular processes involved in molecular mechanisms important in the onset and progress of human diseases. Capparis spinosa L. is an aromatic plant characteristic of the Mediterranean diet. Previous studies have reported that different parts (aerial parts, roots, and seeds) of C. spinosa exert various pharmacological activities. Flower buds of C. spinosa contain several bioactive compounds, including polyphenols and glucosinolates. Two different subspecies of C. spinosa L., namely, C. spinosa L. subsp. spinosa, and C. spinosa L. subsp. rupestris, have been reported. Few studies have been carried out in C. spinosa L. subsp. rupestris. The aim of our study was to investigate the phytochemical profile of floral buds of the less investigated species C. spinosa subsp. rupestris. Moreover, we investigated the effect of the extract from buds of C. spinosa subsp. rupestris (CSE) on cell proliferation, intracellular ROS levels, and expression of the antioxidant and anti-apoptotic enzyme paraoxonase-2 (PON2) in normal and cancer cells. T24 cells and Caco-2 cells were selected as models of advanced-stage human bladder cancer and human colorectal adenocarcinoma, respectively. The immortalized human urothelial cell line (UROtsa) and human dermal fibroblast (HuDe) were chosen as normal cell models. Through an untargeted metabolomic approach based on ultra-high-performance liquid chromatography quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF-MS), our results demonstrate that C. spinosa subsp. rupestris flower buds contain polyphenols and glucosinolates able to exert a higher cytotoxic effect and higher intracellular reactive oxygen species (ROS) production in cancer cells compared to normal cells. Moreover, upregulation of the expression of the enzyme PON2 was observed in cancer cells. In conclusion, our data demonstrate that normal and cancer cells are differentially sensitive to CSE, which has different effects on PON2 gene expression as well. The overexpression of PON2 in T24 cells treated with CSE could represent a mechanism by which tumor cells protect themselves from the apoptotic process induced by glucosinolates and polyphenols.

Glucosinolates and Polyphenols of Colored Cauliflower as Chemical Discriminants Based on Cooking Procedures

The impact of mild oven treatments (steaming or sous-vide) and boiling for 10 min, 25 min, or 40 min on health-promoting phytochemicals in orange and violet cauliflower (Brassica oleracea L. var. botrytis) was investigated. For this purpose, targeted ultra-high performance liquid chromatography–high-resolution mass spectrometry analysis of phenolics and glycosylates, combined with chemometrics, was employed. Regardless of cooking time, clear differentiation of cooked samples obtained using different procedures was achieved, thus demonstrating the distinct impact of cooking approaches on sample phytochemical profile (both, compound distribution and content). The main responsible components for the observed discrimination were derivatives of hydroxycinnamic acid and kaempferol, organic acids, indolic, and aromatic glucosinolates, with glucosativin that was found, for the first time, as a discriminant chemical descriptor in colored cauliflower submitted to steaming and sous-vide. The obtained findings also highlighted a strict relationship between the impact of the cooking technique used and the type of cauliflower. The boiling process significantly affected the phytochemicals in violet cauliflower whereas orange cauliflower boiled samples were grouped between raw and either steamed or sous-vide-cooked samples. Finally, the results confirm that the proposed methodology is capable of discriminating cauliflower samples based on their phytochemical profiles and identifying the cooking procedure able to preserve bioactive constituents.

Caspase 8 Expression Patterns in Meningiomas: A Tissue Microarray Digital Image Analysis

Background: Caspases (cysteine-aspartic proteases) represent a family of enzymes that critically influence cell homeostasis by being involved in inflammation and apoptosis mechanisms. Meningiomas demonstrate the most common intracranial primary central nervous system tumors in adults worldwide.

Aim: Our purpose was to explore the role of caspase 8 expression in meningiomas’ pathological features.

Materials and methods: A total of 50 meningioma cases were included in the study, comprising a broad spectrum of histopathological sub-types. An immunohistochemistry assay was applied on tissue microarray cores followed by digital image analysis.

Results: Overexpression of caspase 8 protein was observed in 21/50 (42%) cases, whereas the rest of them (29/50, 58%) demonstrated moderate to low levels of the molecule. Caspase 8 overall expression was statistically significantly correlated to grade of the examined tumors and to mitotic index (p=0.001,p=0.002, respectively).

Conclusions: Caspase 8 aberrant expression is observed in meningiomas associated with their differentiation grade and mitotic activity. Targeted therapeutic strategies focused on enhancing caspase 8 expression and also inducing the overall apoptotic activity should be a very promising approach in rationally handling sub-groups of meningioma patients.

Set of miRNAs Involved in Sulfur Uptake and the Assimilation Pathway of Indian Mustard (B. juncea) in Response to Sulfur Treatments

MicroRNAs (miRNAs) play an important role in the regulation of gene expression. They play a regulatory role in various nutrient assimilatory pathways of plants; however, their role in the regulation of sulfur uptake and assimilatory pathways in mustard cultivars under high/low sulfur conditions is not elucidated. Sulfur is essential for plant growth and development, and its deficiency can cause a decline in oil seed content and thus lower the economic yield in Brassica juncea. In this study, different miRNAs involved in the regulation of sulfur uptake and assimilation pathways in B. juncea were identified using a psRNA target analyzer and miRanda database tools. The predicted miRNAs that belong to 10 highly conserved families were validated using stem-loop RT-PCR. The B. juncea cultivars Pusa Jaikisan, Pusa Bold, and Varuna were kept in sulfur-excessive (high) and -deficient (insufficient) conditions, and expression studies of miRNAs and their target mRNAs were carried out using qRT-PCR. The correlation between the expression pattern of miRNAs and their target genes showed their potential role in sulfur uptake and assimilation. Analysis with 5' RACE revealed the authentic target of miRNAs. The influence of S treatments on metabolites and sulfur content was also studied using GC-MS and a CHNS analyzer. Our study showed the potential role of miRNAs in the regulation of sulfur uptake and assimilation and put forward the implications of these molecules to enhance the sulfur content of B. juncea.

Natural Products as the Modulators of Oxidative Stress: An Herbal Approach in the Management of Prostate Cancer

Prostate cancer is the most commonly diagnosed and frequently occurred cancer in the males globally. The current treatment strategies available to treat prostate cancer are not much effective and express various adverse effects. Hence, there is an urgent need to identify novel treatment that can improve patient outcome. From times immemorial, natural products are highly recognized for novel drug development for various diseases including cancer. Cancer cells generally maintain higher basal levels of reactive oxygen species (ROS) when compared to normal cells due to its high metabolic rate. However, initiation of excess intracellular ROS production can not be tolerated by the cancer cells and induce several cell death signals which are in contrast to normal cells. Therefore, small molecules of natural origin that induce ROS can potentially kill cancer cells in specific and provide a better opportunity to develop a novel drug therapy. In this review, we elaborated various classes of medicinal compounds and their mechanism of killing prostate cancer cells through direct or indirect ROS generation. This can generate a novel thought to develop promising drug candidate to treat prostate cancer patients.

Discovery of Sulforaphane as an Inducer of Ferroptosis in U-937 Leukemia Cells: Expanding Its Anticancer Potential

In recent years, natural compounds have emerged as inducers of non-canonical cell death. The isothiocyanate sulforaphane (SFN) is a well-known natural anticancer compound with remarkable pro-apoptotic activity. Its ability to promote non-apoptotic cell-death mechanisms remains poorly investigated. This work aimed to explore the capacity of SFN to induce non-apoptotic cell death modalities. SFN was tested on different acute myeloid leukemia cell lines. The mechanism of cell death was investigated using a multi-parametric approach including fluorescence microscopy, western blotting, and flow cytometry. SFN triggered different cell-death modalities in a dose-dependent manner. At 25 μM, SFN induced caspase-dependent apoptosis and at 50 μM ferroptosis was induced through depletion of glutathione (GSH), decreased GSH peroxidase 4 protein expression, and lipid peroxidation. In contrast, necroptosis was not involved in SFN-induced cell death, as demonstrated by the non-significant increase in phosphorylation of receptor-interacting protein kinase 3 and phosphorylation of the necroptotic effector mixed lineage kinase domain-like pseudokinase. Taken together, our results suggest that the antileukemic activity of SFN can be mediated via both ferroptotic and apoptotic cell death modalities.

Effects of BrMYC2/3/4 on Plant Development, Glucosinolate Metabolism, and Sclerotinia sclerotiorum Resistance in Transgenic Arabidopsis thaliana

MYC2/3/4, known as a basic helix-loop-helix (bHLH) transcription factor, directly activate the genes involved in diverse plant development and secondary metabolites biosynthesis. In this study, we identified and cloned five MYC paralogs (BrMYC2/3-1/3-2/4-1/4-2) from Chinese cabbage (Brassica rapa ssp. pekinensis). In-silico analyses for the physicochemical properties suggested that BrMYC2/3-1/3-2/4-2/4-3 are unstable hydrophobic and acidic proteins, while BrMYC4-1 is an unstable hydrophobic and basic protein. BrMYC2/3/4 belong to the bHLH superfamily and are closely related to AthMYC2/3/4 orthologs that mediate the regulation of various secondary metabolites. It was demonstrated that BrMYC2/3/4-GFP fusion protein localized in the nucleus and expression levels of five BrMYC2/3/4 homologous genes all elevated relative to control (Ctrl). When expressed in Arabidopsis under the control of 35S promoter, each of the BrMYC2/3-1/3-2/4-1/4-2 transgenes differentially influenced root and shoot elongation, vegetative phase change, flowering time, plant height and tiller number after flowering, and seed production. Despite the variation of phenotypes between the transgenic lines, all the lines except for BrMYC4-2 exhibited shorter seed length, less seed weight, higher accumulation of glucosinolates (GSs), and resistance to Sclerotinia sclerotiorum than Ctrl. Notably, BrMYC2 overexpression (OE) line significantly reduced the lengths of root and hypocotyl, seed length, and weight, along with faster bolting time and strikingly higher accumulation of total GSs. Accumulation of GSs at the highest levels in the BrMYC2 ^OE line conferred the highest resistance to S. sclerotiorum. Unlike BrMYC3 ^OE and BrMYC4 ^OE , BrMYC2 ^OE stimulated the growth of plant height after fluorescence. The results of this study point to the BrMYC2 overexpression that may provide a beneficial effect on plant growth and development via plant resistance to the fungal pathogen.

Total saponins from Rhizoma Panacis Majoris inhibit proliferation, induce cell cycle arrest and apoptosis and influence MAPK signalling pathways on the colorectal cancer cell

Colorectal cancer (CRC) ranks third in incidence and second in mortality among all types of cancer, and due to its insidious onset and lack of early symptoms, it is usually diagnosed at a later stage. Saponins, a class of compounds abundant in plants, have been reported to possess prominent anti‑tumour properties. The use of ginsenoside Rg3 in the clinical setting was authorized by the National Medicinal Products Administration of China. In the present study, total saponins from Rhizoma Panacis Majoris (RPMTG) were prepared, and the pharmacological mechanisms underlying the anti‑CRC effects of RPMTG were investigated. The effect of RPMTG on the proliferation, cell cycle progression and apoptosis of HCT116 and SW620 cells were detected by MTT, flow cytometry and western blotting assays, and it was demonstrated that RPMTG could inhibit the proliferation of HCT116 and SW620 cells with IC50 values of 315.8 and 355.1 µg/ml, respectively, induce cell cycle arrest in the S and G0/G1 phase, and trigger apoptosis by downregulating the expression of the anti‑apoptotic proteins Bcl‑2, Bcl‑xL and induced myeloid leukaemia cell differentiation protein Mcl‑1, and increasing the expression of the pro‑apoptotic proteins Bax and Bad, cleaved caspased‑3 and poly(ADP)‑ribose polymerase. These findings suggested that RPMTG induced apoptosis through mitochondrial‑related pathways. In addition, RPMTG also decreased the expression of phosphorylated (p)‑extracellular signal‑regulated kinase and increased p‑c‑Jun N‑terminal kinase (p‑JNK) and p‑p38. Moreover, the effects of RPMTG on cell proliferation and apoptosis were partially reversed when the JNK and p38 mitogen‑activated protein kinase (MAPK) pathways were inhibited, indicating that RPMTG triggered apoptosis mainly via regulating JNK and p38 MAPK signalling. Therefore, RPMTG may have potential as an anti‑CRC agent, and further evaluations are needed.

Induction of Apoptosis by Gluconasturtiin-Isothiocyanate (GNST-ITC) in Human Hepatocarcinoma HepG2 Cells and Human Breast Adenocarcinoma MCF-7 Cells

Gluconasturtiin, a glucosinolate present in watercress, is hydrolysed by myrosinase to form gluconasturtiin-isothiocyanate (GNST-ITC), which has potential chemopreventive effects; however, the underlying mechanisms of action have not been explored, mainly in human cell lines. The purpose of the study is to evaluate the cytotoxicity of GNST-ITC and to further assess its potential to induce apoptosis. GNST-ITC inhibited cell proliferation in both human hepatocarcinoma (HepG2) and human breast adenocarcinoma (MCF-7) cells with IC₅₀ values of 7.83 µM and 5.02 µM, respectively. Morphological changes as a result of GNST-ITC-induced apoptosis showed chromatin condensation, nuclear fragmentation, and membrane blebbing. Additionally, Annexin V assay showed proportion of cells in early and late apoptosis upon exposure to GNST-ITC in a time-dependent manner. To delineate the mechanism of apoptosis, cell cycle arrest and expression of caspases were studied. GNST-ITC induced a time-dependent G₂/M phase arrest, with reduction of 82% and 93% in HepG2 and MCF-7 cell lines, respectively. The same treatment also led to the subsequent expression of caspase-3/7 and -9 in both cells demonstrating mitochondrial-associated cell death. Collectively, these results reveal that GNST-ITC can inhibit cell proliferation and can induce cell death in HepG2 and MCF-7 cancer cells via apoptosis, highlighting its potential development as an anticancer agent.

Profiling glucosinolate metabolites in human urine and plasma after broccoli consumption using non-targeted and targeted metabolomic analyses

Broccoli is a popular brassica vegetable and its consumption may decrease the occurrence of cancer in certain populations. To gain insight into the metabolites that may induce physiological responses to broccoli intake, a non-targeted metabolomic approach and a targeted approach for analysis of glucosinolate metabolites were developed using high resolution accurate mass spectrometry. A human study was conducted in which 6 subjects consumed a single meal of 200 g of uncooked broccoli florets. The metabolomic analysis revealed changes in endogenous metabolites and a decrease in hippuric acid after broccoli consumption. Targeted analysis using high-resolution, accurate mass-mass spectrometry (HRAM-MS) enabled detection of low concentrations (nM) of glucosinolate metabolites in human urine and plasma. Glucosinolate metabolites were found in human urine (13) and plasma (8), respectively. Metabolites from methoxyl-indole glucosinolates, arising from broccoli consumption, are reported for the first time. Most glucosinolate metabolites reached their peak concentration in urine 2-4 h after consumption while, in plasma, peak maxima were achieved 2 h after intake. The results suggest that glucoraphanin metabolites (sulforaphane, sulforaphane cysteine, sulforaphane N-acetyl cysteine) and indole metabolites (ascorbigen and methoxyl ascorbigen from indole glucosinolates) may serve as marker compounds for the intake of broccoli.

Complementary therapies for patients with systemic sclerosis

Patients with systemic sclerosis often seek information regarding complementary and nutrition-based therapy. Some study results have shown that vitamins D and E, probiotics, turmeric, l-arginine, essential fatty acids, broccoli, biofeedback, and acupuncture may be beneficial in systemic sclerosis care. However, large randomized clinical trials have not been conducted. This review summarizes current data regarding various complementary therapies in systemic sclerosis and concludes with recommendations.

Satureja hortensis induces cell death and inhibited cell cycle progression in K562 myelogenous and Jurkat T cell leukemia cell lines

Several plants of Satureja genus have shown anti-tumor activity. We investigated the antileukemia effects of different fractions of Satureja hortensis (Summer savory). The growth inhibitory effect of S. hortensis fractions on K562 and Jurkat leukemia cells were determined by MTT assay. The most effective fractions were analyzed by flow cytometry and colorimetric assay for apoptosis induction and cell cycle changes. Various fractions from S. hortensis showed growth inhibitory effects on leukemia cells, among them two hexane and dichloromethane fractions with IC₅₀ values of 32.1-47.8 μg/ml (K562) and 44.3-45.7 μg/ml (Jurkat) were the most effective. According to annexin V staining, both of these fractions significantly induced apoptosis at 50μg/ml in K562 (hexane; 73.06 ± 5.11% and dichloromethane; 96.14 ± 2.33%) and Jurkat cells (hexane; 78.85 ± 11.9% and dichloromethane; 94.05 ± 2.47%) 48 h after treatment. They increased cell accumulation in sub-G1 phase (>50%, p < .001) and decreased number of cells in G0-G1, S and G2M phases. The fractions significantly increased the caspase-3 activity in both cell lines (≈2.5-3.5 fold of untreated cells). Hexane and dichloromethane fractions of S. hortensis had the capacity to induce death and change the cell cycle distribution in leukemia cells; therefore they might be good candidates for more studies in regard to their possible therapeutic usefulness in leukemia.

Induction of Apoptosis and Cytotoxicity by Raphasatin in Human Breast Adenocarcinoma MCF-7 Cells

Glucoraphasatin (GRH), a glucosinolate present abundantly in the plants of the Brassicaceae family, is hydrolyzed by myrosinase to raphasatin, which is considered responsible for its cancer chemopreventive activity; however, the underlying mechanisms of action have not been investigated, particularly in human cell lines. The aims of this study are to determine the cytotoxicity of raphasatin, and to evaluate its potential to cause apoptosis and modulate cell cycle arrest in human breast adenocarcinoma MCF-7 cells. The cytotoxicity was determined following incubation of the cells with glucoraphasatin or raphasatin (0–100 µM), for 24, 48, and 72 h. GRH displayed no cytotoxicity as exemplified by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. When myrosinase was added to the incubation system to convert GRH to raphasatin, cytotoxicity was evident. Exposure of the cells to raphasatin stimulated apoptosis, as was exemplified by cell shrinkage, membrane blebbing, chromatin condensation, and nuclear fragmentation. Moreover, using Annexin V-FITC assay, raphasatin induced apoptosis, as witnessed by changes in cellular distribution of cells, at different stages of apoptosis; in addition, raphasatin caused the arrest of the MCF-7 cells at the G₂ + M phase. In conclusion, raphasatin demonstrated cancer chemopreventive potential against human breast adenocarcinoma (MCF-7) cells, through induction of apoptosis and cell cycle arrest.