Dual drug nanoparticle synergistically induced apoptosis, suppressed inflammation, and protected autophagic response in rheumatoid arthritis fibroblast-like synoviocytes

Rheumatoid arthritis (RA) is a chronic immune-mediated joint inflammatory disorder associated with aberrant activation of fibroblast-like synoviocytes (FLS). Recently, FLS gained importance due to its crucial role in RA pathogenesis, and thus, targeting FLS is suggested as an attractive treatment strategy for RA. FLS-targeted approaches may be combined with disease-modifying antirheumatic drugs (DMARDs) and natural phytochemicals to improve efficacy in RA control and negate immunosuppression. In this study, we assessed the therapeutic effectiveness of DD NP HG in primary RA-FLS cells isolated from the synovial tissue of FCA-induced RA rats. We observed that DD NP HG had good biosafety for healthy FLS cells and, at higher concentrations, a mild inhibitory effect on RA-FLS. The combination therapy (DD NP HG) of MTX NP and PEITC NE in RA-FLS showed a higher rate of apoptosis with significantly reduced LPS-induced expression of pro-inflammatory cytokines (TNF-α, IL-17A, and IL-6) in arthritic FLS. Further, the gene expression studies showed that DD NP HG significantly down-regulated the mRNA expression of IL-1β, RANKL, NFATc1, DKK1, Bcl-xl, Mcl-1, Atg12, and ULK1, and up-regulated the mRNA expression of OPG, PUMA, NOXA and SQSTM1 in LPS-stimulated RA-FLS cells. Collectively, our results demonstrated that DD NP HG significantly inhibited the RA-FLS proliferation via inducing apoptosis, down-regulating pro-inflammatory cytokines, and further enhancing the expression of genes associated with bone destruction in RA pathogenesis. A nanotechnology approach is a promising strategy for the co-delivery of dual drugs to regulate the RA-FLS function and achieve synergistic treatment of RA.

Suppression of neutrophil extracellular traps is responsible for the amelioration of chemotherapeutic intestinal injury by the natural compound PEITC

Intestinal injury is one of the most debilitating side effects of many chemotherapeutic agents, such as irinotecan hydrochloride (CPT-11). Accumulating evidence indicates that neutrophil extracellular traps (NETs) play a critical role in the symptoms of ischemia and inflammation related to chemotherapy. The present study investigated the effects and possible mechanisms of phenethyl isothiocyanate (PEITC) in inhibiting NETs and alleviating chemotherapeutic intestinal injury. CPT-11 induced robust neutrophil activation, as evidenced by increased NETs release, intestinal ischemia, and mRNA expression of inflammatory factors. PEITC prolonged the clotting time of chemotherapeutic mice, improved the intestinal microcirculation, inhibited the expression of inflammatory factors, and protected the tight junctions of the intestinal epithelium. Both in vivo and in vitro experiments revealed that PEITC directly suppresses CPT-11-induced NETs damage to intestinal cells, resulting in significant attenuation of epithelial injury. These results suggest that PEITC may be a novel agent to relieve chemotherapeutic intestinal injury via inhibition of NETs.

Formulation of a dual drug-loaded nanoparticulate co-delivery hydrogel system and its validation in rheumatoid arthritis animal model

Rheumatoid arthritis (RA), a systemic autoimmune disease that dramatically affects patients' quality of life. Given the intricacy of RA's pathophysiology, no single treatment can completely halt the disease progression. Here, we attempted to treat RA holistically and synergistically by co-delivering methotrexate (MTX), a standard slow-acting anti-rheumatic drug, and phenethyl isothiocyanate (PEITC), a bioactive phytochemical, using a sodium alginate (SA)-pluronic F127 (PF-127) in situ hydrogel formulation. Therefore, in the current study, the co-delivery of MTX and PEITC in the nanoparticulate form could help enhance stability and solubility and facilitate greater penetration in the target arthritic tissues. The fabricated MTX NP and PEITC NE were found to have a minimum particle size, PDI, and good zeta potential. Results from in vitro release studies showed that MTX and PEITC were simultaneously released from the DD NP HG matrix over 6-7 days through diffusion and erosion mechanisms. An intra-articular (IA) injection of DD NP HG dramatically reduced chronic inflammation in adjuvant-induced arthritis (AIA) rats, delayed the onset of bone erosion, significantly reduced synovitis, and down-regulated the inflammatory cytokine expression. Most notably, the co-delivery strategy almost entirely restored the morphological features of the ankle joints of RA rats. The hepatic and renal function tests indicated good biological safety for DD NP HG in RA conditions. Taken together, these findings indicated that DD NP HG could achieve good anti-inflammatory activity and reverse cartilage disruption through a synergistic effect between two nanoparticulate forms of MTX and PEITC, which can effectively improve the drawbacks of their free forms.

Thermosensitive smart hydrogel of PEITC ameliorates the therapeutic efficacy in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune condition that accompanies chronic inflammation of joints with limited therapeutic options. Phenethyl isothiocyanate (PEITC), a bioactive phytochemical, exerts its chemopreventive, anti-oxidant, and anti-inflammatory activity via the Nrf-2 pathway. However, limited water solubility, short half-life, and instability are reasons for the low bioavailability of PEITC that hampers clinical application. From studies in healthy rats, the performance of PEITC-loaded chitosan/pluronic F-127 smart hydrogel (PH) as a thermosensitive injectable demonstrated adequate thermosensitivity (gel formation), injectability (ease of administration), biocompatibility (with prolonged contact), pharmacokinetics (sustained drug release), and biosafety (nontoxic to major organs). In the adjuvant-induced arthritis (AIA) rat model, PEITC-hydrogel (PH50) injected into the knee joint lowered RA-related symptoms significantly (paw edema and arthritis score). Further, a marked reduction in bone erosion and inflammation-specific biomarkers was observed. Finally, this study demonstrates a smart injectable hydrogel optimally loaded with PEITC which is safe, biocompatible and exhibits significant therapeutic efficacy in RA conditions.

Phenethyl isothiocyanate as an anti-nutritional factor attenuates deoxynivalenol-induced IPEC-J2 cell injury through inhibiting ROS-mediated autophagy

Deoxynivalenol (DON) is considered to be the most harmful mycotoxin that affects the intestinal health of animals and humans. Phenethyl isothiocyanate (PEITC) in feedstuff is an anti-nutritional factor and impairs nutrient digestion and absorption in the animal intestinal. In the current study, we aimed to explore the effects of PEITC on DON-induced apoptosis, intestinal tight junction disorder, and its potential molecular mechanism in the porcine jejunum epithelial cell line (IPEC-J2). Our results indicated that PEITC treatment markedly alleviated DON-induced cytotoxicity, decreasing the apoptotic cell percentage and pro-apoptotic mRNA/protein levels, and increasing zonula occludens-1 (ZO-1), occludin and claudin-1 mRNA/protein expression. Meanwhile, PEITC treatment ameliorated DON-induced an increase of the inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) mRNA levels and intracellular reactive oxygen species (ROS) level, and a decrease of glutathione peroxidase 1 (GPx1), superoxide dismutase 2 (SOD2), catalase (CAT) and heme oxygenase 1 (HO-1) mRNA levels. Additionally, PEITC treatment significantly down-regulated autophagy-related protein 5 (ATG5), beclin-1 and microtubule-associated protein 1 light chain 3B (LC3-Ⅱ) mRNA/protein levels, decreased the number of green fluorescent protein-microtubule-associated protein 1 light-chain 3 (GFP-LC3) puncta and phosphatidylinositol 3 kinase (PI3K) protein expression, and up-regulated phospho-protein kinase B (p-Akt) and phospho-mammalian target of rapamycin (p-mTOR) protein expression against DON. However, the activation of autophagy by rapamycin, an autophagy agonist, abolished the protective effects of PEITC against DON-induced cytotoxicity, apoptosis and intestinal tight junction disorder. Collectively, PEITC could confer protection against DON-induced porcine intestinal epithelial cell injury by suppressing ROS-mediated autophagy.

Nanodelivery of natural isothiocyanates as a cancer therapeutic

Natural isothiocyanates (ITCs) are phytochemicals abundant in cruciferous vegetables with the general structure, R-NCS. They are bioactive organosulfur compounds derived from the hydrolysis of glucosinolates by myrosinase. A significant number of isothiocyanates have been isolated from different plant sources that include broccoli, Brussels sprouts, cabbage, cauliflower, kale, mustard, wasabi, and watercress. Several ITCs have been demonstrated to possess significant pharmacological properties including: antioxidant, anti-inflammatory, anti-cancer and antimicrobial activities. Due to their chemopreventive effects on many types of cancer, ITCs have been regarded as a promising anti-cancer therapeutic agent without major toxicity concerns. However, their clinical application has been hindered by several factors including their low aqueous solubility, low bioavailability, instability as well as their hormetic effect. Moreover, the typical dietary uptake of ITCs consumed for promotion of good health may be far from their bioactive (or cytotoxic) dose necessary for cancer prevention and/or treatment. Nanotechnology is one of best options to attain enhanced efficacy and minimize hormetic effect for ITCs. Nanoformulation of ITCs leads to enhance stability of ITCs in plasma and emphasize on their chemopreventive effects. This review provides a summary of the potential bioactivities of ITCs, their mechanisms of action for the prevention and treatment of cancer, as well as the recent research progress in their nanodelivery strategies to enhance solubility, bioavailability, and anti-cancer efficacy.

Cancer-preventive effect of phenethyl isothiocyanate through tumor microenvironment regulation in a colorectal cancer stem cell xenograft model

BACKGROUND

Phenethyl isothiocyanate (PEITC) is a glucosinolate derived from cruciferous vegetables and is a cancer-chemopreventive reagent. Cancer stem cells (CSCs) have roles in cancer chemoresistance, invasion, metastasis, and recurrence. Here, we investigated whether PEITC can suppress the properties of CSCs using NCCIT cells and HCT116-derived cancer stem-like cells. Furthermore, we established a CSC xenograft prevention model using nude mice.

PURPOSE

The purpose of this study was to examine the actual cancer-preventive effects of PEITC in vitro and in a xenograft prevention model.

STUDY DESIGN

We assessed the cancer-preventive effects of PEITC on CSCs using a novel xenograft prevention model.

METHODS

NCCIT cells were treated with PEITC, and the expression of pluripotent markers was confirmed by reporter assays, western blotting, and qRT-PCR. In addition, to evaluate the effects of PEITC on CSC properties, sphere cells, which exhibit CSC properties, were established from the HCT116 cells. Furthermore, to examine the inhibitory effects and the underlying mechanism following daily intake of PEITC on CSCs, we performed an animal study in a mouse xenograft model and RNA-sequencing analysis.

RESULTS

PEITC significantly reduced the CSC properties, including clonogenicity and the expression of pluripotent factors. Prior to CSC inoculation in vivo, the PEITC pre-treatment group showed a more effective reduction in the tumor growth rate and expression of CSC markers compared to the post-treatment groups. Furthermore, RNA-sequencing results showed that PEITC pre-treatment remarkably suppressed genes related to inflammatory and immune responses and chemokine-related signaling.

CONCLUSION

PEITC might contribute to the prevention or delay of colorectal cancer growth by inhibiting CSCs via the regulation of inflammatory chemokines, which can affect the tumor microenvironment. Thus, our study suggests that the daily intake of phytochemicals derived from vegetables or dietary supplements could have cancer-preventive effects through regulation of the host-tumor microenvironment.

Nontoxic dose of Phenethyl isothiocyanate ameliorates deoxynivalenol-induced cytotoxicity and inflammation in IPEC-J2 cells

The intestinal tract is a target for the deoxynivalenol (DON), which has adverse effects in animals and humans' health by affecting intestinal functions. Phenethyl isothiocyanate (PEITC) is an important degradation product of glucosinolates (GSLs), belonging to an anti-nutritional factor that affects the digestion and absorption of nutrients in the animals' intestinal. However, little attention has been paid to the interaction and its mechanism between DON and PEITC. Therefore, the purpose of this study was to assess the effects of PEITC on DON-induced cytotoxicity and inflammation, and explore the potential mechanisms in IPEC-J2 cells. Our results showed that DON exposure could decrease the cell viability and pro-inflammatory cytokine expression in IPEC-J2 cells in a dose-dependent manner. PEITC treatment at the concentrations of 1.25-5 μM had no significant effect on IPEC-J2 cells viability, but above 10 μM of PEITC treatment significantly reduced the cell viability. Interestingly, 1.25-5 μM of PEITC treatment could suppress 4 μM of DON-induced decrease in cell viability and increase in pro-inflammatory cytokine expression. Meanwhile, the protein ratios of p-p65/p-65 and p-IκBα/IκBα were markedly decreased in the groups treated with 1.25-5 μM PEITC compared to DON exposure alone. However, the protective effects of PEITC treatment were significantly blocked after pre-treatment with LPS, NF-κB activator, in IPEC-J2 cells. In conclusion, these findings indicated that the nontoxic dose of PEITC could alleviate DON-induced cytotoxicity and inflammation responses via suppressing the NF-κB signaling pathway in IPEC-J2 cells. Our results provide a new theoretical basis for the rational addition of rapeseed meal in animal feedstuff.

Nuclear Factor Erythroid 2 Related Factor 2 Activator JC-5411 Inhibits Atherosclerosis Through Suppression of Inflammation and Regulation of Lipid Metabolism

Phenethyl isothiocyanate is widely present in cruciferous vegetables with multiple biological effects. Here we reported the antiatherogenic effects and the underlying mechanisms of JC-5411 (Phenethyl isothiocyanate formulation) in vitro and in vivo. Luciferase reporter assay showed that JC-5411 increased the activity of nuclear factor erythroid 2-related factor 2 (Nrf2) and antioxidant response element (ARE). JC-5411 treatment significantly increased the protein expression of Nrf2 and its downstream target gene hemeoxygenase 1 (HO-1) in liver of apolipoprotein E deficient (ApoE^−/−) mice. Importantly, JC-5411 treatment significantly reduced atherosclerotic plaque area in both en face aorta and aortic sinus when compared with model group in WD induced ApoE^−/− mice. JC-5411 obviously decreased proinflammatory factors’ levels in serum of ApoE^−/− mice, LPS stimulated macrophages and TNFα induced endothelial cells, respectively. JC-5411 significantly decreased the levels of total cholesterol (TC) and triglyceride (TG) in both serum and liver of ApoE^−/− mice and hyperlipidemic golden hamsters. Mechanism studies showed that JC-5411 exerted anti-inflammatory effect through activating Nrf2 signaling and inhibiting NF-κB and NLRP3 inflammasome pathway. JC-5411 exerted regulating lipid metabolism effect through increasing cholesterol transfer proteins (ABCA1 and LDLR) expression, regulating fatty acids synthesis related genes (p-ACC, SCD1 and FAS), and increasing fatty acids β-oxidation (CPT1A) in vivo. Furthermore, JC-5411 treatment had a favorable antioxidant effect in ApoE^−/− mice by increasing the antioxidant related genes expression. Taken together, we conclude that JC-5411 as a Nrf2 activator has anti-inflammatory, rebalancing lipid metabolism, and antioxidant effects, which makes it as a potential therapeutic agent against atherosclerosis.

Anti-rheumatic activity of Phenethyl isothiocyanate via inhibition of histone deacetylase-1

Rheumatoid Arthritis (RA) affects approximately 1% of the total world population. Despite incessant research and development of new therapeutic agents, management of RA is still a troublesome affair. Histone Deacetylase 1 (HDAC1) is an epigenetic regulator which play important role in pathogenesis of RA. In present study, we hypothesized that Phenethyl isothiocyanate (PEITC), a potent inhibitor of HDAC1, may ameliorate RA. Efficacy of PEITC was evaluated in Complete Freund's Adjuvant (CFA) induced arthritis model in rats. CFA (0.1 ml) was injected subplantarly in the left hind paw on day 0 to all the groups except normal control. The administration of test drug PEITC (10, 24 & 50 mg/kg) and standard drug Ibuprofen started simultaneously and was continued for 21 days. Paw edema, total arthritic index, mobility score, stair climbing ability, behavioral parameters, and bone erosion were evaluated. Further, radiographic studies, TNF-alpha as well as HDAC1 levels in synovial tissue homogenate and histological analysis were performed. Prophylactic treatment of PEITC attenuated paw edema, total arthritic index, mobility score, stair climbing ability, behavioral parameters, and bone erosion in dose dependent manner. Furthermore, there was significant decrease in TNF-alpha as well as HDAC1 levels in synovial tissue homogenate. Histological analysis revealed no cartilage damage, bone erosion, hyperplasia at synovial lining as well as infiltration of inflammatory cells in treatment group. Results of this study suggest potent anti-rheumatoid arthritis activity of Phenethyl isothiocyanate in CFA induced RA model in rats.

Combination of xanthohumol and phenethyl isothiocyanate inhibits NF-κB and activates Nrf2 in pancreatic cancer cells

Phytochemicals such as phenethyl isothiocyanate (PEITC), indole-3-carbinol (I3C), xanthohumol (XAN), and resveratrol (RES) have been shown to target signaling pathways that are involved in the proliferation and survival of different pancreatic cancer (PC) cell lines. While the activity of these compounds alone was extensively studied, their combinations were never assessed. Thus, the aim of this study was to evaluate and compare the effect of PEITC, I3C, XAN, and RES and their combinations on the expression and activation of NF-κB and Nrf2 in human PC cell line PANC-1. The combination of XAN and PEITC was more efficient than the single compounds in reducing the binding of NF-κB p65 subunits to DNA by 47-60% and expression of p65 gene by 28-48%. The combination of XAN and PEITC also enhanced the activation and expression of Nrf2 and subsequently the expression of GSTP, NQO1, and SOD genes which are controlled by this transcription factor. Modulation of the activity of NF-κB and Nrf2 by the combination of XAN and PEITC was found to lead to reduced proliferation of PANC-1 cells. These results suggest that the combination of XAN and PEITC might be considered as a novel strategy for the prophylaxis and/or treatment of PC.

Phenethyl isothiocyanate induces IPEC-J2 cells cytotoxicity and apoptosis via S-G2/M phase arrest and mitochondria-mediated Bax/Bcl-2 pathway

Phenethyl isothiocyanate (PEITC) is one of the glucosinolates (GLs) present in cruciferous vegetables. Although there are many reports of livestock and poultry poisoning caused by plants containing GLs, the actual dosage that causes poisoning and the characteristics of GLs and their metabolites are unclear. Herein, we investigated the inhibitory effects of PEITC on IPEC-J2 cells and examined the mechanisms of PEITC-induced apoptosis via the mitochondrial pathway. Cell viability was determined by the MTT assay, and the levels of reactive oxygen species, mitochondrial membrane potential (∆Ψ), intracellular Ca²⁺ concentration, and cell apoptosis were detected by flow cytometry. IPEC-J2 cells were collected to assess the activities of superoxide dismutase, catalase, and glutathione peroxidase, as well as the contents of glutathione, malondialdehyde, H₂O₂, ATP, and lactate dehydrogenase, using biochemical methods. The levels of cytochrome c, Bax, Bcl-2, caspase-3, caspase-9, poly (ADP-ribose) polymerase (PARP)-1, p53, CDC25C, and cyclin A2 were analyzed by western blotting. We found that PEITC effectively inhibited the growth of IPEC-J2 cells, causing apoptosis. PEITC suppressed the level of mitochondrial membrane potential; released cytochrome c from the mitochondria to the cytoplasm; reduced ATP levels; inhibited Bcl-2 expression; increased Bax expression; and activated caspase-9, caspase-3, and PARP-1, leading to apoptosis. PEITC also induced G₂/M and S phase arrest by affecting cell cycle-associated proteins such as p53, CDC25C, and cyclin A2. We conclude that PEITC causes oxidative stress, cell cycle arrest, and apoptosis in IPEC-J2 cells via a mitochondrial-dependent Bax/Bcl-2 pathway.

Metabolic targets of watercress and PEITC in MCF-7 and MCF-10A cells explain differential sensitisation responses to ionising radiation

PURPOSE

Watercress is a rich source of phytochemicals with anticancer potential, including phenethyl isothiocyanate (PEITC). We examined the potential for watercress extracts and PEITC to increase the DNA damage caused by ionising radiation (IR) in breast cancer cells and to be protective against radiation-induced collateral damage in healthy breast cells. The metabolic events that mediate such responses were explored using metabolic profiling.

METHODS

1H nuclear magnetic resonance spectroscopy-based metabolic profiling was coupled with DNA damage-related assays (cell cycle, Comet assay, viability assays) to profile the comparative effects of watercress and PEITC in MCF-7 breast cancer cells and MCF-10A non-tumorigenic breast cells with and without exposure to IR.

RESULTS

Both the watercress extract and PEITC-modulated biosynthetic pathways of lipid and protein synthesis and resulted in changes in cellular bioenergetics. Disruptions to the redox balance occurred with both treatments in the two cell lines, characterised by shifts in the abundance of glutathione. PEITC enhanced the sensitivity of the breast cancer cells to IR increasing the effectiveness of the cancer-killing process. In contrast, watercress-protected non-tumorigenic breast cells from radiation-induced damage. These effects were driven by changes in the cellular content of the antioxidant glutathione following exposure to PEITC and other phytochemicals in watercress.

CONCLUSION

These findings support the potential prophylactic impact of watercress during radiotherapy. Extracted compounds from watercress and PEITC differentially modulate cellular metabolism collectively enhancing the therapeutic outcomes of radiotherapy.

p53 mutant-type in human prostate cancer cells determines the sensitivity to phenethyl isothiocyanate induced growth inhibition

Background

We reported previously that phenethyl isothiocyanate (PEITC), a dietary compound, can reactivate p53^R175H mutant in vitro and in SK-BR-3 (p53^R175H) breast xenograft model resulting in tumor inhibition. Because of the diversity of human cancers with p53 mutations, these findings raise important questions whether this mechanism operates in different cancer types with same or different p53 mutations. In this study, we investigated whether PEITC recuses mutant p53 in prostate cancer cells harboring different types of p53 mutants, structural and contact, in vitro and in vivo.

Methods

Cell proliferation, cell apoptosis and cell cycle arrest assays were performed to examine the effects of PEITC on prostate cancer cell lines with p53 mutation(s), wild-type p53, p53 null or normal prostate cells in vitro. Western blot analysis was used to monitor the expression levels of p53 protein, activation of ATM and upregulation of canonical p53 targets. Immunoprecipitation, subcellular protein fraction and qRT-PCR was performed to determine change in conformation and restoration of transactivation functions/ inhibition of gain-of-function (GOF) activities to p53 mutant(s). Mice xenograft models were established to evaluate the antitumor efficacy of PEITC and PEITC-induced reactivation of p53 mutant(s) in vivo. Immunohistochemistry of xenograft tumor tissues was performed to determine effects of PEITC on expression of Ki67 and mutant p53 in vivo.

Results

We demonstrated that PEITC inhibits the growth of prostate cancer cells with different “hotspot” p53 mutations (structural and contact), however, preferentially towards structural mutants. PEITC inhibits proliferation and induces apoptosis by rescuing mutant p53 in p53^R248W contact (VCaP) and p53^R175H structural (LAPC-4) mutant cells with differential potency. We further showed that PEITC inhibits the growth of DU145 cells that co-express p53^P223L (structural) and p53^V274F (contact) mutants by targeting p53^P223L mutant selectively, but not p53^V274F. The mutant p53 restored by PEITC induces apoptosis in DU145 cells by activating canonical p53 targets, delaying cells in G1 phase and phosphorylating ATM. Importantly, PEITC reactivated p53^R175H and p53^P223L/V274F mutants in LAPC-4 and DU145 prostate xenograft models, respectively, resulting in significant tumor inhibition.

Conclusion

Our studies provide the first evidence that PEITC’s anti-cancer activity is cancer cell type-independent, but p53 mutant-type dependent.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1267-z) contains supplementary material, which is available to authorized users.

Mechanism of selective anticancer activity of isothiocyanates relies on differences in DNA damage repair between cancer and healthy cells

Purpose

Isothiocyanates (ITCs) are compounds derived from Brassica plants with documented anticancer activity. Molecular mechanisms of their selective activity against cancer cells are still underexplored. In this work, the impact of ITC on DNA replication and damage was compared between PC-3 prostate cancer cells and HDFa normal fibroblasts as well as PNT2 prostate epithelial cells.

Methods

Cells were treated with sulforaphane or phenethyl isothiocyanate. [³H]thymidine incorporation and the level of histone γH2A.X were estimated as indicators of DNA replication and double-strand breaks (DSB), respectively. Levels of HDAC3, CtIP, and p-RPA were investigated by immunoblotting. Comet assay was performed to visualize DNA damage.

Results

ITCs inhibited DNA replication in all tested cell lines, and this activity was independent of reactive oxygen species of mitochondrial origin. It was followed by DSB which were more pronounced in cancer than noncancerous cells. This difference was independent of HDAC activity which was decreased in both cell lines when treated with ITCs. On the other hand, it correlated with faster removal of DSB, and thus, transient activation of repair proteins in normal cells, while in PC-3 prostate cancer, cell DNA repair was significantly less effective.

Conclusion

DNA damage induced by ITCs is a consequence of the block in DNA replication which is observed in both, cancer and normal cells. Selective antiproliferative activity of ITCs towards cancer cells results from less efficient DNA repair in cancer cells relative to normal cells.

Comparing the protective effects of three sulfur compounds against acrylonitrile-induced acute toxicity in CYP2E1-induced rats

Cytochrome P450 2E1 (CYP2E1) can be induced by diabetes mellitus, nonalcoholic liver disease, and obesity. This study assessed the protective effects of three sulfur compounds, namely phenethyl isothiocyanate (PEITC), dimethyl trisulfide (DMTS), and sodium thiosulfate (STS), on acrylonitrile (ACN)-induced acute toxicity in rats enriched with CYP2E1. PEITC and DMTS were administered intragastrically (i.g.), whereas STS was injected intraperitoneally (i.p.) at an identical dose of 0.5 mmol/kg for 3 days in acetone-pretreated rats before ACN (90 mg/kg) injection (i.p.). Acetone-treated rats that expressed high levels of CYP2E1 were more susceptible to ACN-induced acute toxicity. The sulfur compounds reduced the rate of convulsions and loss of the righting reflex in acute ACN-exposed CYP2E1-induced rats; PEITC and DMTS also increased the survival rates. PEITC inhibited hepatic CYP2E1 activity and protected hepatic and cerebral cytochrome c oxidase (CcOx) activities in acute ACN-exposed CYP2E1-enriched rats; DMTS protected hepatic CcOx activity. DMTS attenuated ACN-induced oxidative injury by reducing malondialdehyde (MDA) levels and increasing glutathione content in the brain. STS only reduced cerebral MDA levels, whereas PEITC did not exhibit any antioxidant effects. Collectively, PEITC provided superior protective effects against ACN-induced acute toxicity in rats with increased CYP2E1 activity, followed by DMTS; STS provided limited effects. PEITC and DMTS might be considered as promising chemopreventive agents against ACN-induced acute toxicity in vulnerable subpopulations with increased CYP2E1 activity.

The Role of the Glucosinolate-Myrosinase System in Mediating Greater Resistance of Barbarea verna than B. vulgaris to Mamestra brassicae Larvae

We investigated the influences of two structurally similar glucosinolates, phenethylglucosinolate (gluconasturtiin, NAS) and its (S)-2-hydroxyl derivative glucobarbarin (BAR), as well as their hydrolysis products on larvae of the generalist Mamestra brassicae (Lepidoptera: Noctuidae). Previous results suggested a higher defensive activity of BAR than NAS based on resistance toward M. brassicae larvae of natural plant genotypes of Barbarea vulgaris R. Br. (Brassicaceae) dominated by BAR. In the present study, the hypothesis of a higher defensive activity of BAR than NAS was tested by comparing two Barbarea species similarly dominated either by BAR or by NAS and by testing effects of isolated BAR and NAS on larval survival and feeding preferences. Larvae reared on leaf disks of B. verna (Mill.) Asch. had a lower survival than those reared on B. vulgaris P- and G-chemotypes. Leaves of B. verna were dominated by NAS, whereas B. vulgaris chemotypes were dominated by BAR or its epimer. In addition, B. verna leaves showed a threefold higher activity of the glucosinolate-activating myrosinase enzymes. The main product of NAS from breakdown by endogenous enzymes including myrosinases ("autolysis") in B. verna leaves was phenethyl isothiocyanate, while the main products of BAR in autolyzed B. vulgaris leaves were a cyclized isothiocyanate product, namely an oxazolidine-2-thione, and a downstream metabolite, an oxazolidin-2-one. The glucosinolates BAR and NAS were isolated and offered to larvae on disks of cabbage. Both glucosinolates exerted similar negative effects on larval survival but effects of NAS tended to be more detrimental. Low concentrations of BAR, but not of NAS, stimulated larval feeding, whereas high BAR concentrations acted deterrent. NAS only tended to be deterrent at the highest concentration, but the difference was not significant. Recoveries of NAS and BAR on cabbage leaf disks were similar, and when hydrolyzed by mechanical leaf damage, the same isothiocyanate-type products as in Barbarea plants were formed with further conversion of BAR to cyclic products, (R)-5-phenyloxazolidine-2-thione [(R)-barbarin] and (R)-5-phenyloxazolidin-2-one [(R)-resedine]. We conclude that a previously proposed generally higher defensive activity of BAR than NAS to M. brassicae larvae could not be confirmed. Indeed, the higher resistance of NAS-containing B. verna plants may be due to a combined effect of rather high concentrations of NAS and a relatively high myrosinase activity or other plant traits not investigated yet.

Phenethyl Isothiocyanate Induces Apoptotic Cell Death Through the Mitochondria-dependent Pathway in Gefitinib-resistant NCI-H460 Human Lung Cancer Cells In Vitro

BACKGROUND/AIM

Some lung cancer patients treated with gefitinib develop resistance to this drug resulting in unsatisfactory treatment outcomes. Phenethyl isothiocyanate (PEITC), present in our common cruciferous vegetables, exhibits anticancer activities in many human cancer cell lines. Currently, there is no available information on the possible modification of gefitinib resistance of lung cancer in vitro by PEITC. Thus, the effects of PEITC on gefitinib resistant lung cancer NCI-H460 cells were investigated in vitro.

MATERIALS AND METHODS

The total cell viability, apoptotic cell death, production of reactive oxygen species (ROS) and Ca²⁺, levels of mitochondria membrane potential (ΔΨ_m) and caspase-3, -8 and -9 activities were measured by flow cytometry assay. PEITC induced chromatin condensation was examined by DAPI staining.

RESULTS

PEITC-induced cell morphological changes, decreased total viable cell number and induced apoptotic cell death in NCI-H460 and NCI-H460/G cells. PEITC decreased ROS production in NCI-H460 cells, but increased production in NCI-H460/G cells. PEITC increased Ca²⁺ production, decreased the levels of ΔΨ_m and increased caspase-3, -8 and -9 activities in both NCI-H460 and NCI-H460/G cells. Western blotting was used to examine the effect of apoptotic cell death associated protein expression in NCI-H460 NCI-H460/G cells after exposure to PEITC. Results showed that PEITC increased expression of cleaved caspase-3, PARP, GADD153, Endo G and pro-apoptotic protein Bax in NCI-H460/G cells.

CONCLUSION

Based on these results, we suggest that PEITC induces apoptotic cell death via the caspase- and mitochondria-dependent pathway in NCI-H460/G cells.

Phenethyl isothiocyanate Triggers Apoptosis, Combats Oxidative Stress and Inhibits Growth of Ehrlich Ascites Carcinoma Mouse Model

The aim of this study is to investigate the antitumor activity and possible molecular mechanism of Phenethyl isothiocyanate (PEITC) against Ehrlich ascites carcinoma in-vivo and in-vitro. In-vivo, ascetic fluid volume, body weight, serum malondialdehyde (MDA) level and total antioxidant capacity (TAC) were determined using Ehrlich ascites carcinoma (EAC) bearing mice. In-vitro, MTT assay was used. RT-PCR was used to investigate role of PEITC in apoptosis by analyzing the expression of Bax, caspase-9, and Bcl-2 genes. The effect of PEITC on caspase-9 enzyme activity was also tested. PEITC and/or Doxorubicin (Dox) treatment significantly suppressed EAC growth as compared to EAC/oil control mice. PEITC treatment showed a dose-dependent inhibition of EAC cells as indicated by MTT assay. We found that significant increase in MDA level and decrease in TAC caused by Dox treatment were significantly reduced by combination with PEITC treatment. Bax, caspase-9 genes' expression and caspase-9 enzymatic activity were significantly increased, while Bcl-2 gene expression was significantly decreased in PEITC treated mice. PEITC may act as a promising anticancer agent either alone or more effectively in combination with Dox through apoptotic cell death induction.

Phenethyl isothiocyanate and indole-3-carbinol from cruciferous vegetables, but not furanocoumarins from apiaceous vegetables, reduced PhIP-induced DNA adducts in Wistar rats

SCOPE

We previously showed that apiaceous but not cruciferous vegetables reduced DNA adducts formed by 2-amino-1-methyl-6-phenylimidazo[4, 5-b]pyridine (PhIP) in rats. Here, we report the effects of the putative chemopreventive phytochemicals from these vegetables on PhIP metabolism and DNA adduct formation.

METHODS AND RESULTS

Rats received three supplemented diets: P + I (phenethyl isothiocyanate and indole-3-carbinol), furanocoumarins (FC, 5-methoxypsoralen, 8-methoxypsoralen, and isopimpinellin), and combination (P + I and FC). Phytochemical supplementation matched the levels in vegetables fed in our previous study. After 6 days, rats were injected with PhIP (10 mg/kg body wt) and killed after 24-h urine collection. Compared to the control, P + I increased activity of hepatic cytochrome P450 (CYP) 1A1 (10.1-fold), CYP1A2 (3.62-fold), and sulfotransferase 1A1 (2.70-fold). The combination diet also increased CYP1A1 and CYP1A2 activity. Urinary metabolomics revealed that PhIP metabolite profiles generally agreed with biotransformation enzyme activities. P + I and combination diets reduced PhIP-DNA adducts by 43.5 and 24.1%, respectively, whereas FC had no effect on adducts, compared to the control diet.

CONCLUSION

Effects of phytochemicals on metabolic outcomes and markers of carcinogenesis might differ from fresh vegetables, thus limiting the inferences that one can draw from the effects of purified phytochemicals on the health benefits of the vegetables from which they derive.

Phenethyl isothiocyanate (PEITC) suppresses prostate cancer cell invasion epigenetically through regulating microRNA-194

SCOPE

Tumor metastasis greatly contributes to the mortality of prostate cancer. The glucosinolate-derived phenethyl isothiocyanate (PEITC) has been widely documented to reduce the risk of prostate cancer by modulating multiple biologically relevant processes. Emerging evidence suggests that PEITC may exert its anti-cancer effects through epigenetic mechanisms including microRNAs. Altered levels of miRNA have been linked to tumor malignancy due to their capacity to regulate functional gene expression in carcinogenesis. Here, we assessed the effects of PEITC on miRNA expression which is related to PCa cell invasiveness.

METHODS AND RESULTS

Utilizing oligonucleotide microarray first identified the most affected miRNAs in LNCaP cells after PEITC treatment. Several top altered miRNAs were further validated using quantitative PCR. Interestingly, overexpression of miR-194 suppressed PC3 cell invasion in matrigel-coated Transwell chambers. Bone morphogenetic protein 1 (BMP1) was shown to be a direct target of miR-194. Downregulation of BMP1 by miR-194 or PEITC led to decreased expression of key oncogenic matrix metalloproteinases, MMP2 and MMP9. This in turn resulted in the suppression of tumor invasion.

CONCLUSION

Our results indicate that miR-194 downregulates the expression of oncogenic MMP2 and MMP9 by targeting BMP1, which suggests a potential new mechanistic target by which PEITC suppresses prostate cancer cell invasiveness.

MiR-135a and MRP1 play pivotal roles in the selective lethality of phenethyl isothiocyanate to malignant glioma cells

Amounting evidence has demonstrated that phenethyl isothiocyanate (PEITC) is a strong inducer of reactive oxygen species (ROS) and functions as a selective killer to various human cancer cells. However, it remains obscure whether PEITC has potential selective lethality to malignant glioma cells. Thus in this study, we performed multiple analysis such as MTT assay, Hoechst 33258 staining, flow cytometry, foci formation, RT-PCR, Western blot, and transfection to explore the selective lethality of PEITC to malignant glioma cells and the underlying mechanisms. We found that PEITC induced a selective apoptosis and suppressed tumorigenicity and migration of malignant glioma cells. Furthermore, we found PEITC significantly induced GSH depletion, ROS production, caspase-9 and caspase-3 activation, and miR-135a upregulation in malignant glioma cells but not in normal cells. Moreover, PEITC activated the miR-135a-mitochondria dependent apoptosis pathway as demonstrated by downregulation of STAT6, SMAD5 and Bcl-xl while upregulation of Bax expression and Cytochrome-C release in malignant glioma cell lines but not in the immortalized human normal glial HEB cells. Correspondingly, the above PEITC-induced activation of the ROS-MiR-135a-Mitochondria dependent apoptosis pathways in malignant glioma was attenuated by pre-transfection with miR-135a inhibitor, pre-treatment with multidrug resistance-associated protein 1 (MRP1) inhibitor Sch B, or combination with glutathione (GSH). These results revealed that PEITC selectively induced apoptosis of malignant glioma cells through MRP1-mediated export of GSH to activate ROS-MiR-135a-Mitochondria dependent apoptosis pathway, suggesting a potential application of PEITC for treating glioma.

Iron depletion in HCT116 cells diminishes the upregulatory effect of phenethyl isothiocyanate on heme oxygenase-1

Some of the health-promoting properties of cruciferous vegetables are thought to be partly attributed to isothiocyanates. These phytochemicals can upregulate the expression of certain cytoprotective stress genes, but it is unknown if a particular nutrient is involved. Herein, the objective was to ascertain if adequate iron is needed for enabling HCT116 cells to optimally express heme oxygenase-1 (HO-1) when induced by phenethyl isothiocyanate (PEITC). PEITC increased HO-1 expression and also nuclear translocation of Nrf2, which is a transcription factor known to activate the HO-1 gene. However, in HCT116 cells that were made iron-deficient by depleting intracellular iron with deferoxamine (DFO), PEITC was less able to increase HO-1 expression and nuclear translocation of Nrf2. These suppressive effects of DFO were overcome by replenishing the iron-deficient cells with the missing iron. To elucidate these findings, it was found that PEITC-induced HO-1 upregulation can be inhibited with thiol antioxidants (glutathione and N-acetylcysteine). Furthermore, NADPH oxidase inhibitors (diphenyleneiodonium and apocynin) and a superoxide scavenger (Tiron) each inhibited PEITC-induced HO-1 upregulation. In doing so, diphenyleneiodonium was the most potent and also inhibited nuclear translocation of redox-sensitive Nrf2. Collectively, the results imply that the HO-1 upregulation by PEITC involves an iron-dependent, oxidant signaling pathway. Therefore, it is concluded that ample iron is required to enable PEITC to fully upregulate HO-1 expression in HCT116 cells. As such, it is conceivable that iron-deficient individuals may not reap the full health benefits of eating PEITC-containing cruciferous vegetables that via HO-1 may help protect against multiple chronic diseases.

In vitro studies of phenethyl isothiocyanate against the growth of LN229 human glioma cells

Phenethyl isothiocyanate (PEITC) is one of the best studied members of isothiocyanates (ITC), a variety of edible cruciferous vegetables including broccoli, watercress, and cabbage, and have generated particular interest because of its remarkable chemopreventive activity. Many literature reports proved that phenethyl isothiocyanate exhibited significant anti-cancer chemopreventive effects including lung, glioma and leukemia cancer. In this study, we explored the inhibitory effects as well as mechanisms of PEITC on human glioma LN229 cells. Results demonstrated that PEITC possesses the potential ability to inhibit proliferation, induce apoptosis and arrest cell cycling against LN229 human glioma cells. Moreover, investigated results showed that PEITC inhibited the expression of superoxide dismutase (SOD) and glutathione (GSH), and caused oxidative stress to tumor cells. Collective results suggested us to believe that PEITC can inhibit the growth of LN229 cells and its mechanism can be related to the fact that PEITC can cause oxidative stress to tumor cells.

Phenethyl isothiocyanate inhibits androgen receptor-regulated transcriptional activity in prostate cancer cells through suppressing PCAF

SCOPE

Androgen receptor (AR) signaling is critical for all aspects of prostate growth and tumorigenesis. The glucosinolate-derived phenethyl isothiocyanate (PEITC) has recently been demonstrated to reduce the risk of prostate cancer (PCa) and inhibit PCa cell growth. We previously reported that p300/CBP-associated factor (PCAF), a co-regulator for AR, is upregulated in PCa cells through suppression of the mir-17 gene. Here, we assessed the effects of PEITC on PCAF expression and AR-regulated transcriptional activity in PCa cells.

METHODS AND RESULTS

Using AR-responsive LNCaP cells, we observed the inhibitory effects of PEITC on the dihydrotestosterone-stimulated AR transcriptional activity and cell growth of PCa cells. Interestingly, overexpression of PCAF attenuated the inhibitory effects of PEITC on dihydrotestosterone-stimulated AR transcriptional activity. Expression of PCAF was upregulated in PCa cells through suppression of miR-17. PEITC treatment significantly decreased PCAF expression and promoted transcription of miR-17 in LNCaP cells. Functional inhibition of miR-17 attenuated the suppression of PCAF in cells treated by PEITC.

CONCLUSION

Our results indicate that PEITC inhibits AR-regulated transcriptional activity and cell growth of PCa cells through miR-17-mediated suppression of PCAF, suggesting a new mechanism by which PEITC modulates PCa cell growth.