Sulforaphane-cysteine suppresses invasion via downregulation of galectin-1 in human prostate cancer DU145 and PC3 cells

The recent advances of glucosinolates and their metabolites: Metabolism, physiological functions and potential application strategies

Glucosinolates and their metabolites from Brassicaceae plants have received widespread attention due to their anti-inflammatory effects. Glucosinolates occurs an "enterohepatic circulation" in the body, and the glucosinolates metabolism mainly happens in the intestine. Glucosinolates can be converted into isothiocyanates by intestinal bacteria, which are active substances with remarkable anti-inflammatory, anti-cancer, anti-obesity and neuroprotective properties. This biotransformation can greatly improve the bioactivities of glucosinolates. However, multiple factors in the environment can affect the biotransformation to isothiocyanates, including acidic pH, ferrous ions and thiocyanate-forming protein. The derivatives of glucosinolates under those conditions are usually nitriles and thiocyanates, which may impair the potential health benefits. In addition, isothiocyanates are extremely unstable because of an active sulfhydryl group, which limits their applications. This review mainly summarizes the classification, synthesis, absorption, metabolism, physiological functions and potential application strategies of glucosinolates and their metabolites.

Prostate cancer: Therapeutic prospect with herbal medicine

Prostate cancer (PCa) is a major cause of morbidity and mortality in men worldwide. A geographic variation on the burden of the disease suggested that the environment, genetic makeup, lifestyle, and food habits modulate one's susceptibility to the disease. Although it has been generally thought to be an older age disease, and awareness and timely execution of screening programs have managed to contain the disease in the older population over the last decades, the incidence is still increasing in the population younger than 50. Existing treatment is efficient for PCa that is localized and responsive to androgen. However, the androgen resistant and metastatic PCa are challenging to treat. Conventional radiation and chemotherapies are associated with severe side effects in addition to being exorbitantly expensive. Many isolated phytochemicals and extracts of plants used in traditional medicine are known for their safety and diverse healing properties, including many with varying levels of anti-PCa activities. Many of the phytochemicals discussed here, as shown by many laboratories, inhibit tumor cell growth and proliferation by interfering with the components in the pathways responsible for the enhanced proliferation, metabolism, angiogenesis, invasion, and metastasis in the prostate cells while upregulating the mechanisms of cell death and cell cycle arrest. Notably, many of these agents simultaneously target multiple cellular pathways. We analyzed the available literature and provided an update on this issue in this review article.

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Prostate cancer in a major cause of death in older population worldwide.

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Efficacies of current treatment options are limited in many cases.

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Phytochemicals and extracts isolated from plants show anti-prostate cancer activity with unique mechanisms.

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Certain phytochemicals alone or in combination with current chemotherapy show therapeutic promise.

Sulforaphane downregulated fatty acid synthase and inhibited microtubule-mediated mitophagy leading to apoptosis

We previously demonstrated that sulforaphane (SFN) inhibited autophagy leading to apoptosis in human non-small cell lung cancer (NSCLC) cells, but the underlying subcellular mechanisms were unknown. Hereby, high-performance liquid chromatography-tandem mass spectrometry uncovered that SFN regulated the production of lipoproteins, and microtubule- and autophagy-associated proteins. Further, highly expressed fatty acid synthase (FASN) contributed to cancer malignancy and poor prognosis. Results showed that SFN depolymerized microtubules, downregulated FASN, and decreased its binding to α-tubulin; SFN downregulated FASN, acetyl CoA carboxylase (ACACA), and ATP citrate lyase (ACLY) via activating proteasomes and downregulating transcriptional factor SREBP1; SFN inhibited the interactions among α-tubulin and FASN, ACACA, and ACLY; SFN decreased the amount of intracellular fatty acid (FA) and mitochondrial phospholipids; and knockdown of FASN decreased mitochondrial membrane potential (ΔΨm) and increased reactive oxygen species, mitochondrial abnormality, and apoptosis. Further, SFN downregulated mitophagy-associated proteins Bnip3 and NIX, and upregulated mitochondrial LC3 II/I. Transmission electron microscopy showed mitochondrial abnormality and accumulation of mitophagosomes in response to SFN. Combined with mitophagy inducer CCCP or autophagosome–lysosome fusion inhibitor Bafilomycin A1, we found that SFN inhibited mitophagosome–lysosome fusion leading to mitophagosome accumulation. SFN reduced the interaction between NIX and LC3 II/I, and reversed CCCP-caused FA increase. Furthermore, knockdown of α-tubulin downregulated NIX and BNIP3 production, and upregulated LC3 II/I. Besides, SFN reduced the interaction and colocalization between α-tubulin and NIX. Thus, SFN might cause apoptosis via inhibiting microtubule-mediated mitophagy. These results might give us a new insight into the mechanisms of SFN-caused apoptosis in the subcellular level.

Sulforaphane-cysteine inhibited migration and invasion via enhancing mitophagosome fusion to lysosome in human glioblastoma cells

Here we uncovered the involved subcellular mechanisms that sulforaphane-cysteine (SFN-Cys) inhibited invasion in human glioblastoma (GBM). SFN-Cys significantly upregulated 45 and downregulated 14 microtubule-, mitophagy-, and invasion-associated proteins in GBM cells via HPLC-MS/MS and GEO ontology analysis; SFN-Cys disrupted microtubule by ERK1/2 phosphorylation-mediated downregulation of α-tubulin and Stathmin-1 leading to the inhibition of cell migration and invasion; SFN-Cys downregulated invasion-associated Claudin-5 and S100A4, and decreased the interaction of α-tubulin to Claudin-5. Knockdown of Claudin-5 and S100A4 significantly reduced the migration and invasion. Besides, SFN-Cys lowered the expressions of α-tubulin-mediated mitophagy-associated proteins Bnip3 and Nix. Transmission electron microscopy showed more membrane-deficient mitochondria and accumulated mitophagosomes in GBM cells, and mitochondria fusion might be downregulated because that SFN-Cys downregulated mitochondrial fusion protein OPA1. SFN-Cys increased the colocalization and interplay of LC3 to lysosomal membrane-associated protein LAMP1, aggravating the fusion of mitophagosome to lysosome. Nevertheless, SFN-Cys inhibited the lysosomal proteolytic capacity causing LC3II/LC3I elevation but autophagy substrate SQSTM1/p62 was not changed, mitophagosome accumulation, and the inhibition of migration and invasion in GBM cells. These results will help us develop high-efficiency and low-toxicity anticancer drugs to inhibit migration and invasion in GBM.

Natural Compounds in Prostate Cancer Prevention and Treatment: Mechanisms of Action and Molecular Targets

Prostate cancer (PCa) represents a major cause of cancer mortality among men in developed countries. Patients with recurrent disease initially respond to androgen-deprivation therapy, but the tumor eventually progresses into castration-resistant PCa; in this condition, tumor cells acquire the ability to escape cell death and develop resistance to current therapies. Thus, new therapeutic approaches for PCa management are urgently needed. In this setting, natural products have been extensively studied for their anti-PCa activities, such as tumor growth suppression, cell death induction, and inhibition of metastasis and angiogenesis. Additionally, numerous studies have shown that phytochemicals can specifically target the androgen receptor (AR) signaling, as well as the PCa stem cells (PCSCs). Interestingly, many clinical trials have been conducted to test the efficacy of nutraceuticals in human subjects, and they have partially confirmed the promising results obtained in vitro and in preclinical models. This article summarizes the anti-cancer mechanisms and therapeutic potentials of different natural compounds in the context of PCa prevention and treatment.

Sulforaphane metabolites inhibit migration and invasion via microtubule-mediated Claudins dysfunction or inhibition of autolysosome formation in human non-small cell lung cancer cells

Both sulforaphane-cysteine (SFN-Cys) and sulforaphane-N-acetyl-l-cysteine (SFN-NAC) inhibited cancer migration and invasion, but the underlying mechanisms were not clear. Here we uncovered via tissue microarray assay that high expression of invasion-associated Claudin-5 was correlated to malignant grades in human non-small cell lung cancer (NSCLC) cells. Further, SFN-Cys (10 µM) induced the accumulated phosphorylation of ERK1/2, leading to downregulation of Claudin-5 and upregulation of Claudin-7, and the decrease of Claudin-1 in SK-1 cells and increase of Claudin-1 in A549 cells; knockdown of Claudin-5 significantly reduced invasion, whereas knockdown of Claudin-7 increased invasion; knockdown of Claudin-1 reduced invasion in SK-1 cells, whereas it increased invasion in A549 cells, indicating that SFN-Cys regulated Claudins and inhibited invasion depending on Claudin isotypes and cell types. Furthermore, immunofluorescence staining showed that SFN-Cys triggered microtubule disruption and knockdown of α-tubulin downregulated Claudin-1, 5, and 7, and inhibited migration and invasion, indicating that microtubule disruption contributed to invasive inhibition. Co-immunoprecipitation and confocal microscopy observation showed that SFN-Cys lowered the interaction between α-tubulin and Claudin-1 or 5, or 7. Meanwhile, Western blotting and immunofluorescence staining showed that SFN-NAC (15 µM) downregulated α-tubulin resulting in microtubule disruption; knockdown of α-tubulin increased SFN-NAC-induced LC3 II accumulation in SK-1 cells. Combined with the inhibitor of autolysosome formation, Bafilomycin A1 (100 nM), SFN-NAC inhibited invasion via accumulating LC3 II and blocking formation of autolysosome. Further, SFN-NAC upregulated microtubule-stabilizing protein Tau; knockdown of Tau reduced LC3 II/LC3 I inhibiting migration and invasion. These results indicated that SFN-Cys inhibited invasion via microtubule-mediated Claudins dysfunction, but SFN-NAC inhibited invasion via microtubule-mediated inhibition of autolysosome formation in human NSCLC cells.

Sulforaphane metabolites reduce resistance to paclitaxel via microtubule disruption

Long treatment with paclitaxel (PTX) might increase resistance and side-effects causing a failure in cancer chemotherapy. Here we uncovered that either sulforaphane-cysteine (SFN-Cys) or sulforaphane-N-acetyl-cysteine (SFN-NAC) induced apoptosis via phosphorylated ERK1/2-mediated upregulation of 26 S proteasome and Hsp70, and downregulation of βIII-tubulin, XIAP, Tau, Stathmin1 and α-tubulin causing microtubule disruption in human PTX-resistant non-small cell lung cancer (NSCLC) cells. Knockdown of either βIII-tubulin or α-tubulin via siRNA increased cell sensitivity to PTX, indicating that these two proteins help cells increase the resistance. Tissue microarray analysis showed that overexpression of βIII-tubulin correlated to NSCLC malignant grading. Immunofluorescence staining also showed that SFN metabolites induced a nest-like microtubule protein distribution with aggregation and disruption. Co-immunoprecipitation showed that SFN metabolites reduced the interaction between βIII-tubulin and Tau, and that between α-tubulin and XIAP. The combination of PTX with SFN metabolites decreased the resistance to PTX, and doses of both PTX and SFN metabolites, and enhanced apoptosis resulting from activated Caspase-3-caused microtubule degradation. Importantly, the effective dose of SFN metabolites combined with 20 nM PTX will be low to 4 μM. Thus, we might combine SFN metabolites with PTX for preclinical trial. Normally, more than 20 μM SFN metabolites only leading to apoptosis for SFN metabolites hindered their applications. These findings will help us develop a low-resistance and high-efficiency chemotherapy via PTX/SFN metabolites combination.

Sulforaphane from Cruciferous Vegetables: Recent Advances to Improve Glioblastoma Treatment

Sulforaphane (SFN), an isothiocyanate (ITC) derived from cruciferous vegetables, particularly broccoli and broccoli sprouts, has been widely investigated due to its promising health-promoting properties in disease, and low toxicity in normal tissue. Although not yet fully understood, many mechanisms of anticancer activity at each step of cancer development have been attributed to this ITC. Given the promising data available regarding SFN, this review aimed to provide an overview on the potential activities of SFN related to the cellular mechanisms involved in glioblastoma (GBM) progression. GBM is the most frequent malignant brain tumor among adults and is currently an incurable disease due mostly to its highly invasive phenotype, and the poor efficacy of the available therapies. Despite all efforts, the median overall survival of GBM patients remains approximately 1.5 years under therapy. Therefore, there is an urgent need to provide support for translating the progress in understanding the molecular background of GBM into more complex, but promising therapeutic strategies, in which SFN may find a leading role.

Recent progress in natural dietary non-phenolic bioactives on cancers metastasis

From several decades ago to now, cancer continues to be the leading cause of death worldwide, and metastasis is the major cause of cancer-related deaths. For health benefits, there is a great desire to use non-chemical therapy such as nutraceutical supplementation to prevent pathology development. Over 10,000 different natural bioactives or phytochemicals have been known that possessing potential preventive or supplementary effects for various diseases including cancer. Previously, the in vitro and in vivo anti-invasive and anti-metastatic activities of phenolic acids, monophenol, polyphenol and their derivatives and flavonoids and their derivatives have been reviewed. However, a vast number of natural dietary compounds other than phenolics have been demonstrated to potentially possess the ability to inhibit the invasion and metastasis of various cancers. In this review, we summarize the studies in recent decade on in vitro and in vivo effects and molecular mechanisms of natural bioactives, excluding the phenolics in food, in cancer invasion and metastasis. By combining this review of non-phenolics with the previous phenolics reviews, the puzzle for the contribution of natural dietary bioactives on cancer invasive or/and metastatic progress will be almost complete and more clear.

Chemopreventive Activities of Sulforaphane and Its Metabolites in Human Hepatoma HepG2 Cells

Sulforaphane (SFN) exhibits chemopreventive effects through various mechanisms. However, few studies have focused on the bioactivities of its metabolites. Here, three metabolites derived from SFN were studied, known as sulforaphane glutathione, sulforaphane cysteine and sulforaphane-N-acetylcysteine. Their effects on cell viability, DNA damage, tumorigenicity, cell migration and adhesion were measured in human hepatoma HepG2 cells, and their anti-angiogenetic effects were determined in a 3D co-culture model of human umbilical vein endothelial cells (HUVECs) and pericytes. Results indicated that these metabolites at high doses decreased cancer cell viability, induced DNA damage and inhibited motility, and impaired endothelial cell migration and tube formation. Additionally, pre-treatment with low doses of SFN metabolites protected against H₂O₂ challenge. The activation of the nuclear factor E2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway and the induction of intracellular glutathione (GSH) played an important role in the cytoprotective effects of SFN metabolites. In conclusion, SFN metabolites exhibited similar cytotoxic and cytoprotective effects to SFN, which proves the necessity to study the mechanisms of action of not only SFN but also of its metabolites. Based on the different tissue distribution profiles of these metabolites, the most relevant chemical forms can be selected for targeted chemoprevention.

Sulforaphane metabolites cause apoptosis via microtubule disruption in cancer

Sulforaphane (SFN) inhibited growth in many cancers, but its half-life is 2 h in circulation. However, its metabolites, sulforaphane-cysteine (SFN-Cys) and sulforaphane-N-acetyl-cysteine (SFN-NAC) had longer half-lives and decreased the cell viability in both dose- and time-dependent manners in human prostate cancer. Flow cytometry assay revealed that these two SFN metabolites induced apoptosis with the features such as vacuolization, disappeared nuclear envelope, nuclear agglutination and fragmentation via transmission electron microscopy observation. Western blot showed that the sustained phosphorylation of ERK1/2 mediated by SFN metabolites caused activation and upregulation of cleaved Caspase 3 and downregulation of α-tubulin. High expression of α-tubulin was demonstrated to be positively correlated with cancer pathological grading. Both co-immunoprecipitation and immunofluorescence staining implicated the interaction between SFN metabolite-induced phosphorylated ERK1/2 and α-tubulin, and Caspase 3 cleavage assay showed that α-tubulin might be the substrate for cleaved Caspase 3. More, the SFN metabolite-mediated reduction of α-tubulin increased the depolymerization and instability of microtubules by microtubule polymerization assay. Reversely, microtubule-associated protein Stathmin-1 phosphorylation was increased via phosphorylated ERK1/2 and total Stathmin-1 was reduced, which might promote over-stability of microtubules. Immunofluorescence staining also showed that SFN metabolites induced the 'nest-like' structures of microtubule distribution resulting from the disrupted and aggregated microtubules, and abnormal nuclear division, suggesting that the disturbance of spindle formation and mitosis turned up. Thus, SFN-Cys and SFN-NAC triggered the dynamic imbalance of microtubules, microtubule disruption leading to cell apoptosis. These findings provided a novel insight into the chemotherapy of human prostate cancer.

Downregulation of endometrial mesenchymal marker SUSD2 causes cell senescence and cell death in endometrial carcinoma cells

The cause of death among the majority of endometrial cancer patients involves migration of cancer cells within the peritoneal cavity and subsequent implantation of cancer spheroids into neighbouring organs. It is, thereby, important to identify factors that mediate metastasis. Cell adhesion and migration are modified by the mesenchymal stem cell (MSC) marker Sushi domain containing 2 (SUSD2), a type I transmembrane protein that participates in the orchestration of cell adhesion and migration through interaction with its partner Galactosidase-binding soluble-1 (LGALS1). MSCs have emerged as attractive targets in cancer therapy. Human endometrial adenocarcinoma (Ishikawa) cells were treated with TGFβ (10 ng/ml) for 72h. SUSD2, LGALS1 and MKI67 transcript levels were quantified using qRT-PCR. The proportion of SUSD2 positive (SUSD2+) cells and SMAD2/3 abundance were quantified by FACS and Western blotting, respectively. Senescent cells were identified with β-galactosidase staining; cell cycle and cell death were quantified using Propidium Iodide staining. Treatment of endometrial cancer cells (Ishikawa cells) with TGFβ (10 ng/ml) significantly decreased SUSD2 transcript levels and the proportion of SUSD2 positive cells. Silencing of SUSD2 using siRNA resulted in senescence and cell death of Ishikawa cells via activation of SMAD2/3. These findings suggest that SUSD2 counteracts senescence and cell death and is thus a potential chemotherapeutic target in human endometrial cancer.

Sulforaphane-cysteine-induced apoptosis via phosphorylated ERK1/2-mediated maspin pathway in human non-small cell lung cancer cells

Sulforaphane (SFN) was demonstrated to induce apoptosis in a variety of cancers via multiple mechanisms. However, owing to a short half-life in circulation, SFN was not used for clinical treatment yet. Interestingly, SFN analog, sulforaphane-cysteine (SFN-Cys) has a longer half-life in metabolism, and we previously demonstrated that SFN-Cys inhibited invasion in human prostate cancer cells. Here, we would investigate whether SFN-Cys induces apoptosis and find the underlying mechanisms in human non-small cell lung cancer (NSCLC) cells. Western blots were used to test the molecular linkages among extracellular signal-regulated kinases 1/2 (ERK1/2) and downstream signal molecules. Flow cytometry and fluorescence microscopy were used to detect cell death. Cell proliferation assay showed that SFN-Cys inhibited cell viability following a dose-dependent manner. Abnormal cell morphology was viewed after the cells were exposed to SFN-Cys. Flow cytometry showed that SFN-Cys induced cell apoptosis via a dose-dependent manner. Further, SFN-Cys triggered the activation of ERK1/2, which resulted in the upregulation of maspin, Bax, cleaved caspase-3 and downregulation of pro-caspase-3, Bcl-2, α-tubulin. Meanwhile, we demonstrated that recombinant caspase-3 cleaved α-tubulin in the lysate of cells, which were treated by SFN-Cys. These data indicated that SFN-Cys activated the ERK1/2-mediated mitochondria signaling pathway with maspin upregulation and α-tubulin downregulation leading to apoptosis. These findings will help to develop a novel therapeutic to target NSCLC cells.

Sulforaphane-cysteine induces apoptosis by sustained activation of ERK1/2 and caspase 3 in human glioblastoma U373MG and U87MG cells

We previously demonstrated that sulforaphane (SFN) inhibited invasion via sustained activation of ERK1/2 in human glioblastoma cells. However, sulforaphane-cysteine (SFN-Cys), an analog of SFN, enriched in plasma with longer half-life, had more potentiality to induce apoptosis. Here we investigated the molecular mechanisms of SFN-Cys-induced apoptosis in human glioblastoma U373MG and U87MG cells. Cell viability assay showed that SFN-Cys inhibited cell viability in a dose-dependent manner. Cell morphology observation also showed SFN-Cys increased the phenotype of cell death in a dose-dependent manner. Furthermore, flow cytometry assay showed that SFN-Cys induced apoptosis significantly in a dose-dependent manner in both cell lines. Furthermore, western blot analysis demonstrated that SFN-Cys induced activation of ERK1/2 in a sustained manner and the activation contributed to upregulation of Bax/Bcl-2 ratio and cleaved caspase 3, and these results can be reversed by the ERK1/2 blocker PD98059. Our results showed that SFN-Cys induced cell apoptosis via sustained activation of ERK1/2 and the ERK1/2 mediated signaling pathways such as activation of caspase 3 and apoptosis-related proteins, thus indicating that SFN-Cys might be a more promising therapeutic agent versus SFN to resist glioblastoma cells, especially in Taxol-resistant cancer cells.