Molecular mechanisms of silibinin-mediated cancer chemoprevention with major emphasis on prostate cancer

High-definition FT-IR reveals a synergistic effect on lipid accumulation in prostate cancer cells induced by a combination of X-rays and radiosensitizing drugs

Radiotherapy is one of the most commonly used cancer therapies with many benefits including low toxicity to healthy tissues. However, a major problem in radiotherapy is cancer radioresistance. To enhance the effect of this kind of therapy several approaches have been proposed such as the use of radiosensitizers. A combined treatment of radiotherapy and radiosensitizing drugs leads to a greater effect on cancer cells than anticipated from the addition of both responses (synergism). In this study, high-definition FT-IR imaging was applied to follow lipid accumulation in prostate cancer cells as a response to X-ray irradiation, radiosensitizing drugs, and a combined treatment of X-rays and the drugs. Lipid accumulation induced in the cells by an increasing X-ray dose and the presence of the drugs was analyzed using Principal Component Analysis and lipid staining. Finally, the synergistic effect of the combined therapy (X-rays and radiosensitizers) was confirmed by calculations of the integral intensity of the 2850 cm-1 band.

A comprehensive evaluation of the therapeutic potential of silibinin: a ray of hope in cancer treatment

Natural compounds hold promise in the search for cancer therapies due to their unique chemical structures and combinations that may effectively combat cancer while minimizing toxicity and side effects compared to conventional treatments. Silibinin, a natural lignan, has been found to possess strong anti-cancer activity against several types of human cancers based on emerging research. This study aims to provide an overview of the therapeutic potential of silibinin in the treatment and prevention of cancers. A comprehensive search was conducted using various internet databases such as PubMed, Google Scholar, and ScienceDirect to identify relevant research papers. Silibinin has been shown to exhibit anticancer activity against several types of cancers, including liver, lungs, breast, prostate, colorectal, skin, and bladder cancers. Its multifaceted mechanisms of action contribute to its therapeutic effects. Silibinin exerts antioxidant, anti-inflammatory, anti-proliferative, pro-apoptotic, anti-metastatic, and anti-angiogenic activities, making it a promising candidate for cancer therapy. One of the key mechanisms underlying the anticancer effects of silibinin is its ability to modulate multiple signaling pathways involved in cancer development and progression. It can inhibit the activation of various oncogenic pathways, including PI3K/Akt, NF-κB, Wnt/β-catenin, and MAPK pathways, thereby suppressing cancer cell proliferation, inducing cell cycle arrest, and promoting apoptosis. Silibinin possesses great potential as an effective treatment agent for cancer. The multifaceted mechanisms of action, favorable safety profile, and potential synergistic effects of silibinin with conventional therapies make it an attractive candidate for further investigation and development as a cancer treatment. However, more extensive clinical studies are necessary to fully establish the efficacy, optimal dosage, and long-term effects of silibinin in cancer treatment.

Silibinin effects on cognitive disorders: Hope or treatment?

Objective

Almost all diseases of the nervous system are related to neuroinflammation, oxidative stress, neuronal death, glia activation, and increased pro-inflammatory cytokines. Cognitive disorders are one of the common complications of nervous system diseases. The role of some plant compounds in reducing or preventing cognitive disorders has been determined. Silibinin is a plant bioflavonoid and exhibits various effects on cognitive functions. This article discusses the different mechanisms of the effect of silibinin on cognitive disorders in experimental studies.

Materials and Methods

Databases, including ISI, , Google Scholar, Scopus, Medline and PubMed, were investigated from 2000 to 2021, using related keywords to find required articles.

Results

Silibinin can improve cognitive disorders by different pathways such as reducing neuroinflammation and oxidative stress, activation of reactive oxygen species- Brain-derived neurotrophic factor- Tropomyosin receptor kinase B (ROS-BDNF-TrkB) pathway in the hippocampus, an increase of dendritic spines in the brain, inhibition of hyperphosphorylation of tau protein and increasing the expression of insulin receptor (IR) and insulin-like growth factor receptor 1 (IGF-1R), inhibiting inflammatory responses and oxidative stress in the hippocampus and amygdala, and decrease of Homovanillic acid/Dopamine (HVA/DA) ratio and 3,4-Dihydroxyphenylacetic acid + Homovanillic acid/Dopamine (DOPAC+ HVA/DA) ratio in the prefrontal cortex and 5-hydroxyindoleacetic acid/5-hydroxytryptamine (5-HIAA/5-HT) ratio in the hippocampus.

Conclusion

These results suggest that silibinin can be considered a therapeutic agent for the symptom reduction of cognitive disorders, and it acts by affecting various mechanisms such as inflammation, programmed cell death, and oxidative stress.

Combinatorial approaches of nanotherapeutics for inflammatory pathway targeted therapy of prostate cancer

Prostate cancer (PC) is the most prevalent male urogenital cancer worldwide. PC patients presenting an advanced or metastatic cancer succumb to the disease, even after therapeutic interventions including radiotherapy, surgery, androgen deprivation therapy (ADT), and chemotherapy. One of the hallmarks of PC is evading immune surveillance and chronic inflammation, which is a major challenge towards designing effective therapeutic formulations against PC. Chronic inflammation in PC is often characterized by tumor microenvironment alterations, epithelial-mesenchymal transition and extracellular matrix modifications. The inflammatory events are modulated by reactive nitrogen and oxygen species, inflammatory cytokines and chemokines. Major signaling pathways in PC includes androgen receptor, PI3K and NF-κB pathways and targeting these inter-linked pathways poses a major therapeutic challenge. Notably, many conventional treatments are clinically unsuccessful, due to lack of targetability and poor bioavailability of the therapeutics, untoward toxicity and multidrug resistance. The past decade witnessed an advancement of nanotechnology as an excellent therapeutic paradigm for PC therapy. Modern nanovectorization strategies such as stimuli-responsive and active PC targeting carriers offer controlled release patterns and superior anti-cancer effects. The current review initially describes the classification, inflammatory triggers and major inflammatory pathways of PC, various PC treatment strategies and their limitations. Subsequently, recent advancement in combinatorial nanotherapeutic approaches, which target PC inflammatory pathways, and the mechanism of action are discussed. Besides, the current clinical status and prospects of PC homing nanovectorization, and major challenges to be addressed towards the advancement PC therapy are also addressed.

Chemopreventive efficacy of silibinin against basal cell carcinoma growth and progression in UVB-irradiated Ptch+/- mice

The factors (environmental and genetic) contributing to basal cell carcinoma (BCC) pathogenesis are well-established; however, effective agents for BCC prevention are marred by toxic side-effects. Herein, we assessed the efficacy of flavonolignan silibinin against ultraviolet B (UVB)-induced BCC in Ptch+/- (heterozygous patched homolog 1 gene) mouse model. Both male and female Ptch+/- mice were irradiated with a 240 mJ/cm2 UVB dose 3 times/week for 26 or 46 weeks, with or without topical application of silibinin (9 mg/200 µl in acetone, applied 30 min before or after UVB exposure). Results indicated that silibinin application either pre- or post-UVB exposure for 26 weeks significantly decreased the number of BCC lesions by 65% and 39% (P < 0.001 for both) and the area covered by BCCs (72% and 45%, P < 0.001 for both), respectively, compared to UVB alone. Furthermore, continuous UVB exposure for 46 weeks increased the BCC lesion number and the BCC area covered by ~6 and ~3.4 folds (P < 0.001), respectively. Notably, even in this 46 week prolonged UVB exposure, silibinin (irrespective of pre- or post-UVB treatment) significantly halted the growth of BCCs by 81-94% (P < 0.001) as well as other epidermal lesions; specifically, silibinin treated tissues had less epidermal dysplasia, fibrosarcoma, and squamous cell carcinoma. Immunohistochemistry and immunofluorescence studies revealed that silibinin significantly decreased basal cell proliferation (Ki-67) and the expression of cytokeratins (14 and 15), and Hedgehog signaling mediators Smo and Gli1 in the BCC lesions. Together, our findings demonstrate strong potential of silibinin to be efficacious in preventing the growth and progression of UVB-induced BCC.

Reversing oncogenic transformation with iron chelation

Cancer cells accumulate iron to supplement their aberrant growth and metabolism. Depleting cells of iron by iron chelators has been shown to be selectively cytotoxic to cancer cells in vitro and in vivo. Iron chelators are effective at combating a range of cancers including those which are difficult to treat such as androgen insensitive prostate cancer and cancer stem cells. This review will evaluate the impact of iron chelation on cancer cell survival and the underlying mechanisms of action. A plethora of studies have shown iron chelators can reverse some of the major hallmarks and enabling characteristics of cancer. Iron chelators inhibit signalling pathways that drive proliferation, migration and metastasis as well as return tumour suppressive signalling. In addition to this, iron chelators stimulate apoptotic and ER stress signalling pathways inducing cell death even in cells lacking a functional p53 gene. Iron chelators can sensitise cancer cells to PARP inhibitors through mimicking BRCAness; a feature of cancers trademark genomic instability. Iron chelators target cancer cell metabolism, attenuating oxidative phosphorylation and glycolysis. Moreover, iron chelators may reverse the major characteristics of oncogenic transformation. Iron chelation therefore represent a promising selective mode of cancer therapy.

Transcriptome profiling reveals Silibinin dose-dependent response network in non-small lung cancer cells

Silibinin (SIL), a natural flavonolignan from the milk thistle (Silybum marianum), is known to exhibit remarkable hepatoprotective, antineoplastic and EMT inhibiting effects in different cancer cells by targeting multiple molecular targets and pathways. However, the predominant majority of previous studies investigated effects of this phytocompound in a one particular cell line. Here, we carry out a systematic analysis of dose-dependent viability response to SIL in five non-small cell lung cancer (NSCLC) lines that gradually differ with respect to their intrinsic EMT stage. By correlating gene expression profiles of NSCLC cell lines with the pattern of their SIL IC50 response, a group of cell cycle, survival and stress responsive genes, including some prominent targets of STAT3 (BIRC5, FOXM1, BRCA1), was identified. The relevancy of these computationally selected genes to SIL viability response of NSCLC cells was confirmed by the transient knockdown test. In contrast to other EMT-inhibiting compounds, no correlation between the SIL IC50 and the intrinsic EMT stage of NSCLC cells was observed. Our experimental results show that SIL viability response of differently constituted NSCLC cells is linked to a subnetwork of tightly interconnected genes whose transcriptomic pattern can be used as a benchmark for assessment of individual SIL sensitivity instead of the conventional EMT signature. Insights gained in this study pave the way for optimization of customized adjuvant therapy of malignancies using Silibinin.

Revisiting prostate cancer metabolism: From metabolites to disease and therapy

Prostate cancer (PCa), one of the most commonly diagnosed cancers worldwide, still presents important unmet clinical needs concerning treatment. In the last years, the metabolic reprogramming and the specificities of tumor cells emerged as an exciting field for cancer therapy. The unique features of PCa cells metabolism, and the activation of specific metabolic pathways, propelled the use of metabolic inhibitors for treatment. The present work revises the knowledge of PCa metabolism and the metabolic alterations that underlie the development and progression of the disease. A focus is given to the role of bioenergetic sources, namely, glucose, lipids, and glutamine sustaining PCa cell survival and growth. Moreover, it is described as the action of oncogenes/tumor suppressors and sex steroid hormones in the metabolic reprogramming of PCa. Finally, the status of PCa treatment based on the inhibition of metabolic pathways is presented. Globally, this review updates the landscape of PCa metabolism, highlighting the critical metabolic alterations that could have a clinical and therapeutic interest.

Path of Silibinin from diet to medicine: A dietary polyphenolic flavonoid having potential anti-cancer therapeutic significance

In the last few decades, targeting cancer by the use of dietary phytochemicals has gained enormous attention. The plausible reason and believe or mind set behind this fact is attributed to either lesser or no side effects of natural compounds as compared to the modern chemotherapeutics, or due to their conventional use as dietary components by mankind for thousands of years. Silibinin is a naturally derived polyphenol (a flavonolignans), possess following biochemical features; molecular formula C₂₅H₂₂O₁₀, Molar mass: 482.44 g/mol, Boiling point 793 °C, with strikingly high antioxidant and anti-tumorigenic properties. The anti-cancer properties of Silibinin are determined by a variety of cellular pathways which include induction of apoptosis, cell cycle arrest, inhibition of angiogenesis and metastasis. In addition, Silibinin controls modulation of the expression of aberrant miRNAs, inflammatory response, and synergism with existing anti-cancer drugs. Therefore, modulation of a vast array of cellular responses and homeostatic aspects makes Silibinin an attractive chemotherapeutic agent. However, like other polyphenols, the major hurdle to declare Silibinin a translational chemotherapeutic agent, is its lesser bioavailability. After summarizing the chemistry and metabolic aspects of Silibinin, this extensive review focuses on functional aspects governed by Silibinin in chemoprevention with an ultimate goal of summarizing the evidence supporting the chemopreventive potential of Silibinin and clinical trials that are currently ongoing, at a single platform.

Silymarin-Loaded, Lactobionic Acid-Conjugated Porous PLGA Nanoparticles Induce Apoptosis in Liver Cancer Cells

HepG2 cells (HCC), characterized by epithelial-like morphology, high proliferation rates, and nontumorigenicity, require cost-effective and efficient treatment. Silymarin, a flavonoid extract of Silybum marianum, is effective in the treatment of HCC. Here, we have reported a comparative anticancer study of the well-characterized nanoformulations of lactobionic acid-adorned porous PLGA-encapsulated silymarin (LA-PLGA-Sil) with only porous PLGA-encapsulated silymarin (PLGA-Sil) against HepG2 cells. Treatment of HepG2 cells with LA-PLGA-Sil produced a significant deterioration in cell viability at an essentially low dose as compared with PLGA-Sil, due to the adorned lactobionic acid moiety, which results in better targeting. p53, a tumor suppressor gene, essentially initiates apoptosis in cells procuring wild-type p53 (p53 +/+). In our report, treatment of HepG2 cells (p53 +/+) with LA-PLGA-Sil activated p53, which in turn inhibited the proliferation of cells by instigating cell-cycle arrest and apoptosis in a concentration-dependent manner and simultaneously stabilized the nuclear translocation of NFκB-p65. To explore the effect of LA-PLGA-Sil on the expression of microRNA, we observed that LA-PLGA-Sil markedly upregulated the miR-29b in human HCC cells. Reactivation of the p53 gene by miR-29b targeted Bcl-2 and triggered the sequential activation of mediators such as proapoptotic Bax protein, release of cytochrome c, and the activation of caspase proteins (caspase-3 and caspase-9). Furthermore, the overexpression of NFκB-p65 in HepG2 cells reversed the repression, and this stabilization effect of LA-PLGA-Sil on the nuclear translocation of p65 led to the significant downregulation of miR-29b and successively decreased the p53 expression in LA-PLGA-Sil-treated cells, thereby providing a survival mechanism to HepG2. In entirety, our study demonstrated the extensive potential of LA-PLGA-Sil to instigate the cell death of HepG2 cells via apoptosis by targeting the miR-29b/p53 axis through the stabilization of NFκB. It also impaired the migratory activity of HepG2 cells and thereby furnished a comprehensive way to HCC therapeutic treatment.

Silibinin down-regulates PD-L1 expression in nasopharyngeal carcinoma by interfering with tumor cell glycolytic metabolism

The upregulation of checkpoint inhibitor PD-L1 expression has recently been associated with nasopharyngeal carcinoma (NPC) resistance to therapy. The mechanism of induction of PD-L1 has also been linked to enhanced aerobic glycolysis promoted by HIF1-α dysregulation and LDH-A activity in cancer. Here, we investigated the effect of the anti-tumoral compound Silibinin on HIF-1α/LDH-A mediated cancer cell metabolism and PD-L1 expression in NPC. Our results demonstrate that exposure to Silibinin potently inhibits tumor growth and promotes a shift from aerobic glycolysis toward oxidative phosphorylation. The EBV + NPC cell line C666-1 and glycolytic human tumor explants treated with Silibinin displayed a reduction in LDH-A activity which consistently associated with a reduction in lactate levels. This effect was accompanied by an increase in intracellular citrate levels in C666-1 cells. Accordingly, expression of HIF-1α, a critical regulator of glycolysis, was down-regulated after treatment. This event associated with a down-regulation in PD-L1. Altogether, our results provide evidence that silibinin can alter PD-L1 expression by interfering with HIF-1α/LDH-A mediated cell metabolism in NPC. These results provide a new perspective for Silibinin use to overcome PD-L1 mediated NPC resistance to therapy.

Silybin Prevents Prostate Cancer by Inhibited the ALDH1A1 Expression in the Retinol Metabolism Pathway

Background

Silybin was known to exert inhibition in prostate cancer, but the underlying mechanism remained largely unknown. This study was designed to find out the potential target of Silybin on prostate cancer and explore the relative mechanisms.

Methods

Firstly, we screened the possible targets of Silybin through the PubChem database and Subpathway – GM. Then DU145 cells were transferred to investigate the correction about related targets, magnetic bead sorting and flow cytometry were used to sort and identify the cells. Proliferation, migration and invasion ability of DU145 cells were detected by MTT assay, Transwell assay, plate clonality and sphere formation assay. BALB/c nude mice were constructed models with implanted sarcoma and measured the tumor volume every 5 days as wells tumor weight. The levels of proteins were detected by Western blot and immunocytochemistry. RT-PCR was selected to test the expression of protein’s mRNA.

Results

It was screened out the ALDH1A1 was highly correlated with subpathways of the Silybin risk metabolic pathway. And ALDH1A1 expression was positively correlated RARα with Ets1 by interfering with the ALDH1A1 gene. Importantly, ALDH1A1(+) cells showed proliferation, migration and invasion ability. In addition, it showed that Silybin exerted the inhibition on prostate cells by suppressed the proliferation, migration and invasion ability of cells in vitro experiment. Silybin also reduced the tumor volume and weight. And Silybin displayed obviously reduced the proteins and mRNA of ALDH1A1, RARα, Ets1 and MMP9 expressions.

Conclusion

Our results indicated that Silybin showed inhibition of prostate cancer and the mechanism was involving with downregulating ALDH1A1 expression, thereby inhibiting the activation of RARα and preventing the activation of Ets1 to inhibit the growth and invasion of prostate cancer.

Multidrug Resistance Modulation Activity of Silybin Derivatives and Their Anti-inflammatory Potential

Silybin is considered to be the main biologically active component of silymarin. Its oxidized derivative 2,3-dehydrosilybin typically occurs in silymarin in small, but non-negligible amounts (up to 3%). Here, we investigated in detail complex biological activities of silybin and 2,3-dehydrosilybin optical isomers. Antioxidant activities of pure stereomers A and B of silybin and 2,3-dehydrosilybin, as well as their racemic mixtures, were investigated by using oxygen radical absorption capacity (ORAC) and cellular antioxidant activity (CAA) assay. All substances efficiently reduced nitric oxide production and cytokines (TNF-α, IL-6) release in a dose-dependent manner. Multidrug resistance (MDR) modulating potential was evaluated as inhibition of P-glycoprotein (P-gp) ATPase activity and regulation of ATP-binding cassette (ABC) protein expression. All the tested compounds showed strong dose-dependent inhibition of P-gp pump. Moreover, 2,3-dehydrosilybin A (30 µM) displayed the strongest sensitization of doxorubicin-resistant ovarian carcinoma. Despite these significant effects, silybin B was the only compound acting directly upon P-gp in vitro and also downregulating the expression of respective MDR genes. This compound altered the expression of P-glycoprotein (P-gp, ABCB1), multidrug resistance-associated protein 1 (MRP1, ABCC1) and breast cancer resistance protein (BCRP, ABCG2). 2,3-Dehydrosilybin AB exhibited the most effective inhibition of acetylcholinesterase activity. We can clearly postulate that silybin derivatives could serve well as modulators of a cancer drug-resistant phenotype.

Flavonoids as Epigenetic Modulators for Prostate Cancer Prevention

Prostate cancer (PCa) is a multifactorial disease with an unclear etiology. Due to its high prevalence, long latency, and slow progression, PCa is an ideal target for chemoprevention strategies. Many research studies have highlighted the positive effects of natural flavonoids on chronic diseases, including PCa. Different classes of dietary flavonoids exhibit anti-oxidative, anti-inflammatory, anti-mutagenic, anti-aging, cardioprotective, anti-viral/bacterial and anti-carcinogenic properties. We overviewed the most recent evidence of the antitumoral effects exerted by dietary flavonoids, with a special focus on their epigenetic action in PCa. Epigenetic alterations have been identified as key initiating events in several kinds of cancer. Many dietary flavonoids have been found to reverse DNA aberrations that promote neoplastic transformation, particularly for PCa. The epigenetic targets of the actions of flavonoids include oncogenes and tumor suppressor genes, indirectly controlled through the regulation of epigenetic enzymes such as DNA methyltransferase (DNMT), histone acetyltransferase (HAT), and histone deacetylase (HDAC). In addition, flavonoids were found capable of restoring miRNA and lncRNA expression that is altered during diseases. The optimization of the use of flavonoids as natural epigenetic modulators for chemoprevention and as a possible treatment of PCa and other kinds of cancers could represent a promising and valid strategy to inhibit carcinogenesis and fight cancer.

Silymarin antiproliferative and apoptotic effects: Insights into its clinical impact in various types of cancer

Silymarin is a complex extract isolated from the plant Silybum marianum, widely known for its prominent antioxidant and hepatoprotective effects, although increasing evidences have reported extraordinary antiproliferative and apoptotic abilities. As a result, several signaling pathways involved in cell cycle control, cell proliferation, and cell death have been deconvoluted as critical mechanisms. In this regard, cyclin and cyclin-dependent pathways have been the most studied ones. Following that, apoptotic pathways, such as p53, Akt, STAT-3, Ras, and caspases pathways, have been extensively studied, although other mechanisms involved in inflammation and angiogenesis have also been highlighted as silymarin-likely targets in cancer therapy. Therefore, the main challenge of this review is to discuss the diverse molecular mechanisms for silymarin antiproliferative and apoptotic effects; most of them largely studied in various types of cancers so far. Clinical trials and combination therapies related to silymarin application in cancer prevention and treatment are presented as well.

Silibinin Differentially Decreases the Aggressive Cancer Phenotype in an In Vitro Model of Obesity and Prostate Cancer

Aim: Obesity increases the risk for aggressive and fatal prostate cancer (PCa). The bioactive compound silibinin has been researched for its chemopreventative properties and may benefit obese or overweight individuals with PCa.Methods: This study used an in vitro model of obesity exposing prostate cancer cells to sera from obese, overweight, or normal weight males with or without the addition of silibinin. Molecular activity was assayed as well as the phenotype of PCa cells with various treatments.Results: Obesity increased the expression of proliferative signaling including COX-2, IL-6, AKT, ERK, and AR, which was attenuated with silibinin. Cell growth, and invasive capacity of prostate cancer cells was increased with obese and overweight sera, and silibinin was able to mitigate this affect. However, there are limitations to this study in that an in vivo model was not used to validate these in vitro results nor a co-culture model, which may better recapitulate the tumor microenvironment.Conclusions: Silibinin may be a safe intervention for those with or at risk for prostate cancer, and it may be the most beneficial for obese or overweight males.

Silibinin to improve cancer therapeutic, as an apoptotic inducer, autophagy modulator, cell cycle inhibitor, and microRNAs regulator

Silibinin is a natural plant polyphenol with high antioxidant and anticancer properties, which causes broad-spectrum efficacy against cancer, including cell cycle arrest and apoptosis in most cancer cell types. Silibinin, by modulating the apoptosis, cell cycle progression and autophagic pathways in various cellular and molecular routs might be used to design more effective anticancer strategies. Silibinin also regulates aberrant miRNAs expression linked to many aspects of cell biology in cancer. Maybe the most interesting aspect of silibinin is its ability to trigger multiple cellular signaling pathways to induce a particular biologic effect in various cell types. This review discusses investigations supporting the ability of silibinin to be as a natural modulator of involved cellular biological events in cancer progression. In this review, we introduce the salient features of silibinin therapy to optimize clinical outcomes for oncology patients. The goal of the treatments is to make it possible to eliminate the tumor with the minimum side effects and cure the patient in the early stage cancer. Therefore, plant extracts such as silibinin can be included in the treatments.

Evaluation of the Cytotoxicity and Genotoxicity of Flavonolignans in Different Cellular Models

Flavonolignans are the main components of silymarin, which represents 1.5-3% of the dry fruit weight of Milk thistle (Silybum marianum L. Gaernt.). In ancient Greece and Romania, physicians and herbalists used the Silybum marianum to treat a range of liver diseases. Besides their hepatoprotective action, silymarin flavonolignans have many other healthy properties, such as anti-platelet and anti-inflammatory actions. The aim of this study was to evaluate the toxic effect of flavonolignans on blood platelets, peripheral blood mononuclear cells (PBMCs) and human lung cancer cell line-A549-using different molecular techniques. We established that three major flavonolignans: silybin, silychristin and silydianin, in concentrations of up to 100 µM, have neither a cytotoxic nor genotoxic effect on blood platelets, PMBCs and A549. We also saw that silybin and silychristin have a protective effect on cellular mitochondria, observed as a reduction of spontaneous mitochondrial DNA (mtDNA) damage in A549, measured as mtDNA copies, and mtDNA lesions in ND1 and ND5 genes. Additionally, we observed that flavonolignans increase the blood platelets' mitochondrial membrane potential and reduce the generation of reactive oxygen species in blood platelets. Our current findings show for the first time that the three major flavonolignans, silybin, silychristin and silydianin, do not have any cytotoxicity and genotoxicity in various cellular models, and that they actually protect cellular mitochondria. This proves that the antiplatelet and anti-inflammatory effect of these compounds is part of our molecular health mechanisms.

Silibinin sensitizes TRAIL-mediated apoptosis by upregulating DR5 through ROS-induced endoplasmic reticulum stress-Ca2+-CaMKII-Sp1 pathway

In this study, we addressed how silibinin enhances tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis in various cancer cells. Combined treatment with silibinin and TRAIL (silibinin/TRAIL) induced apoptosis accompanied by the activation of caspase-3, caspase-8, caspase-9, and Bax, and cytosolic accumulation of cytochrome c. Anti-apoptotic proteins such as Bcl-2, IAP-1, and IAP-2 were inhibited as well. Silibinin also triggered TRAIL-induced apoptosis in A549 cells through upregulation of death receptor 5 (DR5). Pretreatment with DR5/Fc chimeric protein and DR5-targeted small interfering RNA (siRNA) significantly blocked silibinin/TRAIL-mediated apoptosis in A549 cells. Furthermore, silibinin increased the production of reactive oxygen species (ROS), which led to the induction of TRAIL-mediated apoptosis through DR5 upregulation. Antioxidants such as N-acetyl-L-cysteine and glutathione reversed the apoptosis-inducing effects of TRAIL. Silibinin further induced endoplasmic reticulum (ER) stress as was indicated by the increase in ER marker proteins such as PERK, eIF2α, and ATF-4, which stimulate the expression of CCAAT/enhancer binding protein homologous protein (CHOP). CHOP-targeted siRNA eliminated the induction of DR5 and resulted in a significant decrease in silibinin/TRAIL-mediated apoptosis. We also found that silibinin/TRAIL-induced apoptosis was accompanied with intracellular influx of Ca²⁺, which was stimulated by ER stress and the Ca²⁺ chelator, ethylene glycol tetraacetic acid (EGTA). Ca²⁺/calmodulin-dependent protein kinase (CaMKII) inhibitor, K252a, blocked silibinin/TRAIL-induced DR5 expression along with TRAIL-mediated apoptosis. Accordingly, we showed that ROS/ER stress-induced CaMKII activated Sp1, which is an important transcription factor for DR5 expression. Our results showed that silibinin enhanced TRAIL-induced apoptosis by upregulating DR5 expression through the ROS-ER stress-CaMKII-Sp1 axis.

Silibinin sensitizes chemo-resistant breast cancer cells to chemotherapy

CONTEXT

Multiple drug resistance is the major obstacle to conventional chemotherapy. Silibinin, a nontoxic naturally occurring compound, has anticancer activity and can increase the cytotoxic effects of chemotherapy in various cancer models.

OBJECTIVE

To evaluate the effects of silibinin on enhancing the sensitivity of chemo-resistant human breast cell lines to doxorubicin (DOX) and paclitaxel (PAC).

MATERIALS AND METHODS

The cells were treated with silibinin (at 50 to 600 μM concentrations) and/or chemo drugs for 24 and 48 h, then cell viability and changes in oncogenic proteins were determined by MTT assay and Western blotting/RT-PCR, respectively. Flow cytometry was used to study apoptosis in the cells receiving different treatments. The antitumorigenic effects of silibinin (at 200 to 400 μM concentration) were evaluated by mammosphere assay.

RESULTS

Silibinin exerted significant growth inhibitory effects with IC₅₀ ranging from 200 to 570 μM in different cell lines. Treatment of DOX-resistant MDA-MB-435 cells with silibinin at 200 μM reduced DOX IC₅₀ from 71 to 10 μg/mL and significantly suppressed the key oncogenic pathways including STAT3, AKT, and ERK in these cells. Interestingly treatment of DOX-resistant MDA-MB-435 cells with silibinin at 400 μM concentration for 48 h induced a 50% decrease in the numbers of colonies as compared with DMSO-treated cells. Treatment of PAC-resistant MCF-7 cells with silibinin at 400 μM concentration generated synergistic effects when it was used in combination with PAC at 250 nM concentration (CI = 0.81).

CONCLUSION

Silibinin sensitizes chemo-resistant cells to chemotherapeutic agents and can be useful in treating breast cancers.

Increased Loading, Efficacy and Sustained Release of Silibinin, a Poorly Soluble Drug Using Hydrophobically-Modified Chitosan Nanoparticles for Enhanced Delivery of Anticancer Drug Delivery Systems

Conventional delivery of anticancer drugs is less effective due to pharmacological drawbacks such as lack of aqueous solubility and poor cellular accumulation. This study reports the increased drug loading, therapeutic delivery, and cellular accumulation of silibinin (SLB), a poorly water-soluble phenolic compound using a hydrophobically-modified chitosan nanoparticle (pCNP) system. In this study, chitosan nanoparticles were hydrophobically-modified to confer a palmitoyl group as confirmed by 2,4,6-Trinitrobenzenesulfonic acid (TNBS) assay. Physicochemical features of the nanoparticles were studied using the TNBS assay, and Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analyses. The FTIR profile and electron microscopy correlated the successful formation of pCNP and pCNP-SLB as nano-sized particles, while Dynamic Light Scattering (DLS) and Field Emission-Scanning Electron Microscopy (FESEM) results exhibited an expansion in size between pCNP and pCNP-SLB to accommodate the drug within its particle core. To evaluate the cytotoxicity of the nanoparticles, a Methylthiazolyldiphenyl-tetrazolium bromide (MTT) cytotoxicity assay was subsequently performed using the A549 lung cancer cell line. Cytotoxicity assays exhibited an enhanced efficacy of SLB when delivered by CNP and pCNP. Interestingly, controlled release delivery of SLB was achieved using the pCNP-SLB system, conferring higher cytotoxic effects and lower IC₅₀ values in 72-h treatments compared to CNP-SLB, which was attributed to the hydrophobic modification of the CNP system.

HM015k, a Novel Silybin Derivative, Multi-Targets Metastatic Ovarian Cancer Cells and Is Safe in Zebrafish Toxicity Studies

This study was designed to determine the in vitro mechanisms by which the novel silybin derivative, (E)-3-(3-(benzyloxy) phenyl)-1-(4-hydroxyphenyl)prop-2-en-1-one (HM015k or 15k), produces its anticancer efficacy in ovarian cancer cells. Compound 15k induced apoptosis in ovarian cancer cells in a time-dependent manner by significantly upregulating the expression of Bax and Bak and downregulating the expression of Bcl-2. Interestingly, 15k induced the cleavage of Bax p21 into its more efficacious cleaved form, Bax p18. In addition, caspase 3 and caspase 9 were cleaved to their active forms, inducing the cleavage of poly ADP ribose polymerase (PARP) and β-catenin. Furthermore, in OV2008 cells, 15k induced significant cleavage in nuclear β-catenin to primarily inactive fragments of lower molecular weight. Furthermore, 15k reversed the metastatic potential of OV2008 cells by inhibiting their migration and invasiveness. The mesenchymal phenotype in OV2008 was reversed by 15k, causing cells to be rounder with epithelial-like phenotypes. The 15k-induced reversal was further confirmed by significant upregulation of the E-cadherin expression, an epithelial marker, while N-cadherin, a mesenchymal marker, was downregulated in OV2008 cells. Compound 15k inhibited the expression of the oncogenic c-Myc protein, downregulated proteins DVL3 and DVL2 and significantly upregulated cyclin B1. Also, 15k significantly downregulated the expression levels of ABCG2 and ABCB1 transporters in resistant ABCG2 overexpressing H460/MX20 and resistant ABCB1 overexpressing MDCK/MDR1 cells, respectively. Finally, 15k was safe in zebrafish in vivo model at concentrations up to 10 μM and induced no major toxicities in cardiac, morphology and swimming position parameters. Overall, 15k is a multi-targeted inhibitor with efficacy against metastatic and resistant ovarian cancer. Future in vivo studies will be conducted to determine the efficacy of 15k in tumor-bearing animals.

Synergistic Anticancer Effects of Silibinin and Chrysin in T47D Breast Cancer Cells

Objective:

Breast cancer is one of the most significant causes of female cancer death worldwide. Although several chemotherapeutics have been developed to treat this type of cancer, issues remain such as low survival rates and high reoccurrence after chemotherapy and radiotherapy. To explore a chemopreventive approach to enhancing breast cancer treatment efficacy, the antiproliferative effects of a combination of chrysin and silibinin, two herbal substances, in T47D breast cancer cells were assessed.

Materials and Methods:

Cytotoxicity of the agents singly and in combination was evaluated by MTT assay. Also, qRT-PCR was used to measure the expression levels of hTERT and cyclin D1 genes after 48 h treatment.

Results:

Cell viability assays revealed that chrysin or silibinin alone inhibited proliferation in a dose and time-dependent manner, and combining the drugs synergistically induced growth inhibition in the breast cancer cell line. The precise nature of this interaction was further analyzed by the median-effect method, where the combination indices (CI) were <1 for combination treatments, indicating synergism regarding T47D cell proliferation. qPCR results showed that the drug combination also synergistically down-regulated the mRNA levels of hTERT and cyclin D1 at all used concentrations compared with the drugs used alone after 48 h treatment (P ≤ 0.05).

Conclusion:

The data provide evidence that synergistic antiproliferative effects of Chrysin and Silibinin are linked to the down-regulation of cyclin D1 and hTERT genes, and suggest that their combination may have therapeutic value in treatment of breast cancer.

Cytotoxic and toxicogenomic effects of silibinin in bladder cancer cells with different TP53 status

Silibinin is a natural phenol found in the seeds of the milk thistle plant. Recent data have shown its effectiveness for preventing/treating bladder tumours. Therefore, in this study we investigated the cytotoxic and toxicogenetic activity of silibinin in bladder cancer cells with different TP53 statuses. Two bladder urothelial carcinoma cell lines were used: RT4 (wild-type TP53 gene) and T24 (mutated TP53 gene). Cell proliferation, clonogenic survival, apoptosis rates, genotoxicity and relative expression profile of FRAP/mTOR, FGFR3, AKT2 and DNMT1 genes and of miR100 and miR203 were evaluated. Silibinin promoted decreased proliferation and increased late apoptosis in TP53 mutated cells. Increased early apoptosis rates, primary DNA damage, and decrease of cell colonies in the clonogenic survival assay were detected in both RT4 and T24 cell lines. Down-regulation of FRAP/mTOR, AKT2, FGFR3, DNMT1 and miR100 expression occurred in RT4 cells. Modulation of miR203 was observed in both cell lines. In conclusion, despite the reduction of clone formation in both cell lines, the toxicogenomic effect of silibinin on FRAP/mTOR, AKT2, FGFR3, DNMT1 and miR100 was dependent on the TP53 status. Taken together, the data confirmed the role of silibinin as an antiproliferative compound, whose mechanism of action was related to the TP53 status.

Effect of Silibinin on Maspin and ERα Gene Expression in MCF-7 Human Breast Cancer Cell Line

BACKGROUND AND OBJECTIVE

According to reports, a serine protease inhibitor (Maspin) suppresses metastasis, invasion and angiogenesis in breast and prostate cancers. Silibinin is a natural polyphenolic flavonoid with anti-cancer activity. We assessed the effects of silibinin on cell viability, maspin and ERα gene expression in MCF-7 cell line.

METHODS

The human MCF-7 breast cancer cell line was cultured in Dulbecco's Modified Eagle's Medium (DMEM) and treated with different concentrations of silibinin (100-600 μg/mL) for 24, 48 and 72 hours. The cytotoxic effect of silibinin on MCF-7 viability was determined using Methyl-Thiazolyl-Tetrazolium (MTT) assay by IC50 determination. The fold changes of Maspin and ERα expression were determined by reverse-transcription real-time Polymerase Chain Reaction (PCR). All experiments on the cells were performed in triplicates.

RESULTS

The maximum inhibitory effect of silibinin on cell viability was observed at 600 μg/mL after 72-hour incubation (p = 0.001). Incubation of the cells with silibinin for 48 and 72 hours significantly decreased IC50 values to 250 and 207 μg/mL (p = 0.005 and p= 0.006), respectively. The expression of maspin and ERα in the treated cells compared to controls was significantly decreased following treatment with different concentrations of silibinin during a 24-hour period.

CONCLUSIONS

Silibinin reduces both maspin and ERα gene expression in MCF-7 cell line. The therapeutic effect of silibinin on the treatment of breast cancer may be mediated by the reduction of ERα expression. For verifying this hypothesis and the possible therapeutic implication of silibinin on breast cancer, further studies in this direction are necessary.

A Novel Role of Silibinin as a Putative Epigenetic Modulator in Human Prostate Carcinoma

Silibinin, extracted from milk thistle (Silybum marianum L.), has exhibited considerable preclinical activity against prostate carcinoma. Its antitumor and chemopreventive activities have been associated with diverse effects on cell cycle, apoptosis, and receptor-dependent mitogenic signaling pathways. Here we hypothesized that silibinin's pleiotropic effects may reflect its interference with epigenetic mechanisms in human prostate cancer cells. More specifically, we have demonstrated that silibinin reduces gene expression levels of the Polycomb Repressive Complex 2 (PRC2) members Enhancer of Zeste Homolog 2 (EZH2), Suppressor of Zeste Homolog 12 (SUZ12), and Embryonic Ectoderm Development (EED) in DU145 and PC3 human prostate cancer cells, as evidenced by Real Time Polymerase Chain Reaction (RT-PCR). Furthermore immunoblot and immunofluorescence analysis revealed that silibinin-mediated reduction of EZH2 levels was accompanied by an increase in trimethylation of histone H3 on lysine (Κ)-27 residue (H3K27me3) levels and that such response was, in part, dependent on decreased expression levels of phosphorylated Akt (ser473) (pAkt) and phosphorylated EZH2 (ser21) (pEZH2). Additionally silibinin exerted other epigenetic effects involving an increase in total DNA methyltransferase (DNMT) activity while it decreased histone deacetylases 1-2 (HDACs1-2) expression levels. We conclude that silibinin induces epigenetic alterations in human prostate cancer cells, suggesting that subsequent disruptions of central processes in chromatin conformation may account for some of its diverse anticancer effects.

Silibinin-mediated metabolic reprogramming attenuates pancreatic cancer-induced cachexia and tumor growth

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related deaths in the US. Cancer-associated cachexia is present in up to 80% of PDAC patients and is associated with aggressive disease and poor prognosis. In the present studies we evaluated an anti-cancer natural product silibinin for its effectiveness in targeting pancreatic cancer aggressiveness and the cachectic properties of pancreatic cancer cells and tumors. Our results demonstrate that silibinin inhibits pancreatic cancer cell growth in a dose-dependent manner and reduces glycolytic activity of cancer cells. Our LC-MS/MS based metabolomics data demonstrates that silibinin treatment induces global metabolic reprogramming in pancreatic cancer cells. Silibinin treatment diminishes c-MYC expression, a key regulator of cancer metabolism. Furthermore, we observed reduced STAT3 signaling in silibinin-treated cancer cells. Overexpression of constitutively active STAT3 was sufficient to substantially revert the silibinin-induced downregulation of c-MYC and the metabolic phenotype. Our in vivo investigations demonstrate that silibinin reduces tumor growth and proliferation in an orthotopic mouse model of pancreatic cancer and prevents the loss of body weight and muscle. It also improves physical activity including grip strength and latency to fall in tumor-bearing mice. In conclusion, silibinin-induced metabolic reprogramming diminishes cell growth and cachectic properties of pancreatic cancer cells and animal models.

Corneal toxicity induced by vesicating agents and effective treatment options

The vesicating agents sulfur mustard (SM) and lewisite (LEW) are potent chemical warfare agents that primarily cause damage to the ocular, skin, and respiratory systems. However, ocular tissue is the most sensitive organ, and vesicant exposure results in a biphasic injury response, including photophobia, corneal lesions, corneal edema, ulceration, and neovascularization, and may cause loss of vision. There are several reports on ocular injury from exposure to SM, which has been frequently used in warfare. However, there are very few reports on ocular injury by LEW, which indicate that injury symptoms appear instantly after exposure and faster than SM. In spite of extensive research efforts, effective therapies for vesicant-induced ocular injuries, mainly to the most affected corneal tissue, are not available. Hence, we have established primary human corneal epithelial cells and rabbit corneal organ culture models with the SM analog nitrogen mustard, which have helped to test the efficacy of potential therapeutic agents. These agents will then be further evaluated against in vivo SM- and LEW-induced corneal injury models, which will assist in the development of potential broad-spectrum therapies against vesicant-induced ocular injuries.

Deregulation of miR-21 and miR-155 and their putative targets after silibinin treatment in T47D breast cancer cells

OBJECTIVES

MicroRNAs (miRNAs) are a class of short RNAs that control the biological processes including cell proliferation, apoptosis and development. Aberrant expression of miRNAs was determined in the different stages of tumor development and metastasis. To study the effect of silibinin on miRNAs expression, we evaluated quantitative expression of miR-21 and miR-155 as two oncomiRs and several potential targets in silibinin-treated T47D cells.

MATERIALS AND METHODS

The rate of proliferation and apoptosis was measured in silibinin-treated and untreated cells. The expression levels of miR-21 and miR-155 were evaluated in T47D cells treated with silibinin (100 µg/ml). Also, their putative targets were predicted in apoptotic pathways using multiple algorithms; as a confirmation, the transcription level of APAF-1, CASP-9 and BID was evaluated.

RESULTS

In silibinin-treated cells, death was occurred in a dose and time-dependent manner. miR-21 and miR-155 was downregulated in cells treated with silibinin (100 µg/ml). It is noticeable that the expression of their potential targets including CASP-9 and APAF-1 was increased in silibinin-treated cells after 48 hr.

CONCLUSION

Our findings showed a correlation between the expression of miR-21 and miR-155 and apoptosis in silibinin treated T47D cells. It seems that miRNAs such as miR-21 and miR-155 were regulated by silibinin. Also, increase in the transcript level of APAF-1 and CASP-9 after downregulation of miR-21 and miR-155 might indicate that these genes were targeted by aforementioned miRNAs in T47D cells.

Silibinin and colorectal cancer chemoprevention: a comprehensive review on mechanisms and efficacy

Globally, the risk of colorectal cancer (CRC) as well as the incidence of mortality associated with CRC is increasing. Thus, it is imperative that we look at alternative approaches involving intake of non-toxic natural dietary/non-dietary agents, for the prevention of CRC. The ultimate goal of this approach is to reduce the incidence of pre-neoplastic adenomatous polyps and prevent their progression to more advanced forms of CRC, and use these natural agents as a safe intervention strategy during the clinical course of this deadly malignancy. Over the years, pre-clinical studies have shown that silibinin (a flavonolignan isolated from the seeds of milk thistle, Silybum marianum) has strong preventive and therapeutic efficacy against various epithelial cancers, including CRC. The focus of the present review is to provide a comprehensive tabular summary, categorically for an easy accessibility and referencing, pertaining to the efficacy and associated mechanisms of silibinin against CRC growth and progression.

Silibinin Preferentially Radiosensitizes Prostate Cancer by Inhibiting DNA Repair Signaling

Radiotherapy, a frequent mode of cancer treatment, is often restricted by dose-related toxicity and development of therapeutic resistance. To develop a novel and selective radiosensitizer, we studied the radiosensitizing effects and associated mechanisms of silibinin in prostate cancer. The radiosensitizing effect of silibinin with ionizing radiation (IR) was assessed on radioresistant prostate cancer cell lines by clonogenic, cell cycle, cell death, and DNA repair assays. Tumor xenograft growth, immunohistochemical (IHC) analysis of tumor tissues, and toxicity-related parameters were measured in vivo. Silibinin (25 μmol/L) enhanced IR (2.5-10 Gy)-caused inhibition (up to 96%, P < 0.001) of colony formation selectively in prostate cancer cells, and prolonged and enhanced IR-caused G2-M arrest, apoptosis, and ROS production. Mechanistically, silibinin inhibited IR-induced DNA repair (ATM and Chk1/2) and EGFR signaling and attenuated the levels of antiapoptotic proteins. Specifically, silibinin suppressed IR-induced nuclear translocation of EGFR and DNA-PK, an important mediator of DSB repair, leading to an increased number of γ-H2AX (ser139) foci suggesting lesser DNA repair. In vivo, silibinin strongly radiosensitized DU145 tumor xenograft inhibition (84%, P < 0.01) with higher apoptotic response (10-fold, P < 0.01) and reduced repair of DNA damage, and rescued the mice from IR-induced toxicity and hematopoietic injury. Overall, silibinin enhanced the radiotherapeutic response via suppressing IR-induced prosurvival signaling and DSB repair by inhibiting nuclear translocation of EGFR and DNA-PK. Because silibinin is already in phase II clinical trial for prostate cancer patients, the present finding has translational relevance for radioresistant prostate cancer.

Silibinin inhibits aberrant lipid metabolism, proliferation and emergence of androgen-independence in prostate cancer cells via primarily targeting the sterol response element binding protein 1

Prostate cancer (PCA) kills thousands of men every year, demanding additional approaches to better understand and target this malignancy. Recently, critical role of aberrant lipogenesis is highlighted in prostate carcinogenesis, offering a unique opportunity to target it to reduce PCA. Here, we evaluated efficacy and associated mechanisms of silibinin in inhibiting lipid metabolism in PCA cells. At physiologically achievable levels in human, silibinin strongly reduced lipid and cholesterol accumulation specifically in human PCA cells but not in non-neoplastic prostate epithelial PWR-1E cells. Silibinin also decreased nuclear protein levels of sterol regulatory element binding protein 1 and 2 (SREBP1/2) and their target genes only in PCA cells. Mechanistically, silibinin activated AMPK, thereby increasing SREBP1 phosphorylation and inhibiting its nuclear translocation; AMPK inhibition reversed silibinin-mediated decrease in nuclear SREBP1 and lipid accumulation. Additionally, specific SREBP inhibitor fatostatin and stable overexpression of SREBP1 further confirmed the central role of SREBP1 in silibinin-mediated inhibition of PCA cell proliferation and lipid accumulation and cell cycle arrest. Importantly, silibinin also inhibited synthetic androgen R1881-induced lipid accumulation and completely abrogated the development of androgen-independent LNCaP cell clones via targeting SREBP1/2. Together, these mechanistic studies suggest that silibinin would be effective against PCA by targeting critical aberrant lipogenesis.

Silibinin suppresses NPM-ALK, potently induces apoptosis and enhances chemosensitivity in ALK-positive anaplastic large cell lymphoma

Nucleophosmin-anaplastic lymphoma kinase (NPM-ALK), an oncogenic fusion protein carrying constitutively active tyrosine kinase, is known to be central to the pathogenesis of ALK-positive anaplastic large cell lymphoma (ALK+ALCL). Here, it is reported that silibinin, a non-toxic naturally-occurring compound, potently suppressed NPM-ALK and effectively inhibited the growth and soft agar colony formation of ALK+ALCL cells. By western blots, it was found that silibinin efficiently suppressed the phosphorylation/activation of NPM-ALK and its key substrates/downstream mediators (including STAT3, MEK/ERK and Akt) in a time- and dose-dependent manner. Correlating with these observations, silibinin suppressed the expression of Bcl-2, survivin and JunB, all of which are found to be upregulated by NPM-ALK and pathogenetically important in ALK+ALCL. Lastly, silibinin augmented the chemosensitivity of ALK+ALCL cells to doxorubicin, particularly the small cell sub-set expressing the transcriptional activity of Sox2, an embryonic stem cell marker. To conclude, the findings suggest that silibinin might be useful in treating ALK+ALCL.

Silibinin attenuates methotrexate-induced pulmonary injury by targeting oxidative stress

The aim of the present study was to assess the protective effect of silibinin against methotrexate (MTX)-induced pulmonary toxicity. Rats were divided into four groups (MTX, MTX + silibinin, silibinin and control. MTX was injected intraperitoneally (i.p) into female Wistar rats (10 mg/kg/day for 3 days), which resulted in significant increases in the serum levels of alanine aminotransferase, aspartate aminotransferase and oxidant enzymes, including nitric oxide and myeloperoxidase. Furthermore, significant reductions were detected in the serum activity levels of the antioxidative enzymes, glutathione peroxidase and superoxide dismutase, when compared with the control group. However, administration of silibinin (100 mg/kg/day for 10 days, i.p.) was shown to ameliorate the MTX-induced pulmonary toxicity, as indicated by the normalization of the oxidative stress parameters. Furthermore, silibinin treatment was demonstrated to reduce the histopathological changes associated with MTX. In conclusion, silibinin exhibited protective effects against MTX-induced pulmonary toxicity, which may be attributed to its antioxidant activity.

Silymarin and hepatocellular carcinoma: a systematic, comprehensive, and critical review

The blessed milk thistle (Silybum marianum L.), a flowering plant native to Mediterranean Europe, has been consumed and extensively used as a cure for various chronic liver ailments over several centuries. Milk thistle extract, known as silymarin, is a complex mixture of seven major flavonolignans and one flavonoid. The phytoconstituents of silymarin owe their therapeutic and hepatoprotective effects to their strong antioxidant and anti-inflammatory properties. Primary liver cancer, also known as hepatocellular carcinoma (HCC), occurs in a milieu of oxidative stress and inflammation. The etiology of HCC includes chronic infection with hepatitis B and C viruses, cirrhosis, and exposure to dietary and environmental hepatocarcinogens. Current therapeutic options for HCC, including surgical resection and liver transplantation, have limited benefits and are essentially ineffective. Chemoprevention, using phytochemicals with potent antioxidant and anti-inflammatory properties, represents a fascinating strategy, which has been a subject of intense investigation in the recent years. In this review, we explore the potential role of silymarin as a chemopreventive and therapeutic agent for HCC. The review systematically evaluates the preclinical in-vitro and in-vivo studies investigating the effects of silymarin and its constituents on HCC. The biochemical mechanisms involved in the anti-liver-cancer effects of silymarin have been presented. The current status of clinical studies evaluating the potential of role of silymarin in liver cancer, especially that caused by hepatitis C virus, has also been examined. Potential challenges and future directions of research involved in the 'bench-to-bedside' transition of silymarin phytoconstituents for the chemoprevention and treatment of HCC have also been discussed.

A Perspective on Prostate Carcinogenesis and Chemoprevention

In this perspective, modifiable carcinogenic factors for the prostate are summarized. This is followed by a discussion of how current knowledge about causation of prostate cancer and chemoprevention of prostate cancer can be used to develop preventive strategies. Prostate cancer is a slowly developing cancer which offers opportunities for preventive interventions. Only a few randomized clinical trials of prostate cancer prevention have been completed. The SELECT study with selenium and vitamin E did not find protective effects, but in two trials with 5α-reductase inhibitors risk was reduced about 25%, showing that chemoprevention is possible and indicating that the androgen receptor is a suitable target. Besides smoking cessation and reduction of obesity, there are no known dietary or life style interventions that will have a major impact on prostate cancer risk. Inflammation of the prostate is an attractive target and aspirin may be a promising candidate agent, but has not been addressed yet in preclinical and clinical studies. Antioxidants other than selenium and vitamin E are unlikely to be very effective and data on several dietary supplements are not encouraging. More candidate agents need to be identified and tested in relevant and adequate preclinical models and Phase II trials that have predictive value for outcome of Phase III randomized studies. Doing this will require a systematic approach comparing preclinical and clinical study outcomes to determine their predictive value of preventive efficacy.

Tissue invasion and metastasis: Molecular, biological and clinical perspectives

Cancer is a key health issue across the world, causing substantial patient morbidity and mortality. Patient prognosis is tightly linked with metastatic dissemination of the disease to distant sites, with metastatic diseases accounting for a vast percentage of cancer patient mortality. While advances in this area have been made, the process of cancer metastasis and the factors governing cancer spread and establishment at secondary locations is still poorly understood. The current article summarizes recent progress in this area of research, both in the understanding of the underlying biological processes and in the therapeutic strategies for the management of metastasis. This review lists the disruption of E-cadherin and tight junctions, key signaling pathways, including urokinase type plasminogen activator (uPA), phosphatidylinositol 3-kinase/v-akt murine thymoma viral oncogene (PI3K/AKT), focal adhesion kinase (FAK), β-catenin/zinc finger E-box binding homeobox 1 (ZEB-1) and transforming growth factor beta (TGF-β), together with inactivation of activator protein-1 (AP-1) and suppression of matrix metalloproteinase-9 (MMP-9) activity as key targets and the use of phytochemicals, or natural products, such as those from Agaricus blazei, Albatrellus confluens, Cordyceps militaris, Ganoderma lucidum, Poria cocos and Silybum marianum, together with diet derived fatty acids gamma linolenic acid (GLA) and eicosapentanoic acid (EPA) and inhibitory compounds as useful approaches to target tissue invasion and metastasis as well as other hallmark areas of cancer. Together, these strategies could represent new, inexpensive, low toxicity strategies to aid in the management of cancer metastasis as well as having holistic effects against other cancer hallmarks.

Silymarin as a Natural Antioxidant: An Overview of the Current Evidence and Perspectives

Silymarin (SM), an extract from the Silybum marianum (milk thistle) plant containing various flavonolignans (with silybin being the major one), has received a tremendous amount of attention over the last decade as a herbal remedy for liver treatment. In many cases, the antioxidant properties of SM are considered to be responsible for its protective actions. Possible antioxidant mechanisms of SM are evaluated in this review. (1) Direct scavenging free radicals and chelating free Fe and Cu are mainly effective in the gut. (2) Preventing free radical formation by inhibiting specific ROS-producing enzymes, or improving an integrity of mitochondria in stress conditions, are of great importance. (3) Maintaining an optimal redox balance in the cell by activating a range of antioxidant enzymes and non-enzymatic antioxidants, mainly via Nrf2 activation is probably the main driving force of antioxidant (AO)  action of SM. (4) Decreasing inflammatory responses by inhibiting NF-κB pathways is an emerging mechanism of SM protective effects in liver toxicity and various liver diseases. (5) Activating vitagenes, responsible for synthesis of protective molecules, including heat shock proteins (HSPs), thioredoxin and sirtuins and providing additional protection in stress conditions deserves more attention. (6) Affecting the microenvironment of the gut, including SM-bacteria interactions, awaits future investigations. (7) In animal nutrition and disease prevention strategy, SM alone, or in combination with other hepatho-active compounds (carnitine, betaine, vitamin B₁₂, etc.), might have similar hepatoprotective effects as described in human nutrition.

Emerging potential of natural products for targeting mucins for therapy against inflammation and cancer

Deregulated mucin expression is a hallmark of several inflammatory and malignant pathologies. Emerging evidence suggests that, apart from biomarkers, these deregulated mucins are functional contributors to the pathogenesis in inflammation and cancer. Both overexpression and downregulation of mucins in various organ systems is associated with pathobiology of inflammation and cancer. Restoration of mucin homeostasis has become an important goal for therapy and management of such disorders has fueled the quest for selective mucomodulators. With improved understanding of mucin regulation and mechanistic insights into their pathobiological roles, there is optimism to find selective non-toxic agents capable of modulating mucin expression and function. Recently, natural compounds derived from dietary sources have drawn attention due to their anti-inflammatory and anti-oxidant properties and low toxicity. Considerable efforts have been directed towards evaluating dietary natural products as chemopreventive and therapeutic agents; identification, characterization and synthesis of their active compounds; and improving their delivery and bioavailability. We describe the current understanding of mucin regulation, rationale for targeting mucins with natural products and discuss some natural products that modulate mucin expression and functions. We further discuss the approaches and parameters that should guide future research to identify and evaluate selective natural mucomodulators for therapy.

Nutrition, dietary interventions and prostate cancer: the latest evidence

Prostate cancer (PCa) remains a leading cause of mortality in US men and the prevalence continues to rise world-wide especially in countries where men consume a 'Western-style' diet. Epidemiologic, preclinical and clinical studies suggest a potential role for dietary intake on the incidence and progression of PCa. 'This minireview provides an overview of recent published literature with regard to nutrients, dietary factors, dietary patterns and PCa incidence and progression. Low carbohydrates intake, soy protein, omega-3 (w-3) fat, green teas, tomatoes and tomato products and zyflamend showed promise in reducing PCa risk or progression. A higher saturated fat intake and a higher β-carotene status may increase risk. A 'U' shape relationship may exist between folate, vitamin C, vitamin D and calcium with PCa risk. Despite the inconsistent and inconclusive findings, the potential for a role of dietary intake for the prevention and treatment of PCa is promising. The combination of all the beneficial factors for PCa risk reduction in a healthy dietary pattern may be the best dietary advice. This pattern includes rich fruits and vegetables, reduced refined carbohydrates, total and saturated fats, and reduced cooked meats. Further carefully designed prospective trials are warranted.