Silibinin modulates TNF-α and IFN-γ mediated signaling to regulate COX2 and iNOS expression in tumorigenic mouse lung epithelial LM2 cells

Silybin restores glucose uptake after tumour necrosis factor-alpha and lipopolysaccharide stimulation in 3T3-L1 adipocytes

Obesity is associated with a low-grade chronic inflammatory process characterized by higher circulating TNFα levels, thus contributing to insulin resistance. This study evaluated the effect of silybin, the main bioactive component of silymarin, which has anti-inflammatory properties, on TNFα levels and its impact on glucose uptake in the adipocyte cell line 3T3-L1 challenged with two different inflammatory stimuli, TNFα or lipopolysaccharide (LPS). Silybin's pre-treatment effect was evaluated in adipocytes pre-incubated with silybin (30 or 80 µM) before challenging with the inflammatory stimuli (TNFα or LPS). For the post-treatment effect, the adipocytes were first challenged with the inflammatory stimuli and then post-treated with silybin. After treatments, TNFα production, glucose uptake, and GLUT4 protein expression were determined. Both inflammatory stimuli increased TNFα secretion, diminished GLUT4 expression, and significantly decreased glucose uptake. Silybin 30 µM only reduced TNFα secretion after the LPS challenge. Silybin 80 µM as post-treatment or pre-treatment decreased TNFα levels, improving glucose uptake. However, glucose uptake enhancement induced by silybin did not depend on GLUT4 protein expression. These results show that silybin importantly reduced TNFα levels and upregulates glucose uptake, independently of GLUT4 protein expression.

Insights on the Role of Polyphenols in Combating Cancer Drug Resistance

Chemotherapy resistance is still a serious problem in the treatment of most cancers. Many cellular and molecular mechanisms contribute to both inherent and acquired drug resistance. They include the use of unaffected growth-signaling pathways, changes in the tumor microenvironment, and the active transport of medicines out of the cell. The antioxidant capacity of polyphenols and their potential to inhibit the activation of procarcinogens, cancer cell proliferation, metastasis, and angiogenesis, as well as to promote the inhibition or downregulation of active drug efflux transporters, have been linked to a reduced risk of cancer in epidemiological studies. Polyphenols also have the ability to alter immunological responses and inflammatory cascades, as well as trigger apoptosis in cancer cells. The discovery of the relationship between abnormal growth signaling and metabolic dysfunction in cancer cells highlights the importance of further investigating the effects of dietary polyphenols, including their ability to boost the efficacy of chemotherapy and avoid multidrug resistance (MDR). Here, it is summarized what is known regarding the effectiveness of natural polyphenolic compounds in counteracting the resistance that might develop to cancer drugs as a result of a variety of different mechanisms.

Role of Plant-Derived Flavonoids in Cancer Treatment

Flavonoids are polyphenolic phytochemicals, which occur naturally in plants and possess both anti-oxidant and pro-oxidant properties. Flavonoids are gaining increasing popularity in the pharmaceutical industry as healthy and cost-effective compounds. Flavonoids show beneficial pharmacological activities in the treatment and prevention of various types of diseases. They are natural and less toxic agents for cancer chemotherapy and radiotherapy via regulation of multiple cell signaling pathways and pro-oxidant effects. In this review, we have summarized the mechanisms of action of selected flavonoids, and their pharmacological implications and potential therapeutic applications in cancer therapy.

Plant-Derived Natural Non-Nucleoside Analog Inhibitors (NNAIs) against RNA-Dependent RNA Polymerase Complex (nsp7/nsp8/nsp12) of SARS-CoV-2

The emergence of fast-spreading SARS-CoV-2 mutants has sparked a new phase of COVID-19 pandemic. There is a dire necessity for antivirals targeting highly conserved genomic domains on SARS-CoV-2 that are less prone to mutation. The nsp12, also known as the RNA-dependent RNA-polymerase (RdRp), the core component of 'SARS-CoV-2 replication-transcription complex', is a potential well-conserved druggable antiviral target. Several FDA-approved RdRp 'nucleotide analog inhibitors (NAIs)' such as remdesivir, have been repurposed to treat COVID-19 infections. The NAIs target RdRp protein translation and competitively block the nucleotide insertion into the RNA chain, resulting in the inhibition of viral replication. However, the replication proofreading function of nsp14-ExoN could provide resistance to SARS-CoV-2 against many NAIs. Conversely, the 'non-nucleoside analog inhibitors (NNAIs)' bind to allosteric sites on viral polymerase surface, change the redox state; thereby, exert antiviral activity by altering interactions between the enzyme substrate and active core catalytic site of the RdRp. NNAIs neither require metabolic activation (unlike NAIs) nor compete with intracellular pool of nucleotide triphosphates (NTPs) for anti-RdRp activity. The NNAIs from phytonutrient origin are potential antiviral candidates compared to their synthetic counterparts. Several in-silico studies reported the antiviral spectrum of natural phytonutrient-NNAIs such as Suramin, Silibinin (flavonolignan), Theaflavin (tea polyphenol), Baicalein (5,6,7-trihydroxyflavone), Corilagin (gallotannin), Hesperidin (citrus bioflavonoid), Lycorine (pyrrolidine alkaloid), with superior redox characteristics (free binding energy, hydrogen-bonds, etc.) than antiviral drugs (i.e. remdesivir, favipiravir). These phytonutrient-NNAIs also exert anti-inflammatory, antioxidant, immunomodulatory and cardioprotective functions, with multifunctional therapeutic benefits in the clinical management of COVID-19.

Lead Nitrate Induces Inflammation and Apoptosis in Rat Lungs Through the Activation of NF-κB and AhR Signaling Pathways

Lead (Pb) is one of the most frequent hazardous air contaminants, where the lungs are particularly vulnerable to its toxicity. However, the Pb distribution and its impact on lung inflammation/apoptosis and particularly the involvement of nuclear factor kappa B (NF-κB) and aryl hydrocarbon receptor (AhR) signaling pathways in Pb-induced lung toxicity have not yet been fully investigated. Adult male Wistar albino rats were exposed to Pb nitrate 25, 50, and 100 mg/kg b.w. orally for 3 days. The histopathological changes of several rat organs were analyzed using hematoxylin and eosin staining. The concentrations of Pb ion in different organ tissues were quantified using inductive coupled plasma mass spectrometry, while gas chromatography-mass spectrometry was used to identify organic compounds. The changes in the mRNA and protein expression levels of inflammatory and apoptotic genes in response to Pb exposure were quantified by using RT-PCR and Western blot analyses, respectively. Treatment of rats with Pb for three consecutive days significantly increased the accumulation of Pb in lung tissues causing severe interstitial inflammation. Pb treatment also increased the percentage of lung apoptotic cells and modulated apoptotic genes (Bc2, p53, and TGF-α), inflammatory markers (IL-4, IL-10, TNF-α), and oxidative stress biomarkers (iNOS, CYP1A1, EphX) in rat lung tissues. These effects were associated with a significant increase in organic compounds, such as 3-nitrotyrosine and myeloperoxidase, and some inorganic elements, such as selenium. Importantly, the Pb-induced lung inflammation and apoptosis were associated with a proportional increase in the expression of NF-κB and AhR mRNAs and proteins. These findings clearly show that Pb induces severe inflammation and apoptosis in rat lungs and suggest that NF-κB and AhR may play a role in Pb-induced lung toxicity.

Medicinal Plants in Cancer Treatment: Contribution of Nuclear Factor-Kappa B (NF-kB) Inhibitors

Nuclear factor-kappa B (NF-κB) is one of the principal inducible proteins that is a predominant transcription factor known to control the gene expression in mammals and plays a pivotal role in regulating cell signalling in the body under certain physiological and pathological conditions. In cancer cells, such as colon, breast, pancreatic, ovarian, melanoma, and lymphoma, the NF-κB pathway has been reported to be active. In cellular proliferation, promoting angiogenesis, invasion, metastasis of tumour cells and blocking apoptosis, the constitutive activity of NF-κB signalling has been reported. Therefore, immense attention has been given to developing drugs targeting NF-κB signalling pathways to treat many types of tumours. They are a desirable therapeutic target for drugs, and many studies concentrated on recognizing compounds. They may be able to reverse or standstill the growth and spread of tumours that selectively interfere with this pathway. Recently, numerous substances derived from plants have been evaluated as possible inhibitors of the NF-κB pathway. These include various compounds, such as flavonoids, lignans, diterpenes, sesquiterpenes, polyphenols, etc. A study supported by folk medicine demonstrated that plant-derived compounds could suppress NF-κB signalling. Taking this into account, the present review revealed the anticancer potential of naturally occurring compounds which have been verified both by inhibiting the NF-κB signalling and suppressing growth and spread of cancer and highlighting their mechanism of NF-κB inhibition.

Role of Silymarin in Cancer Treatment: Facts, Hypotheses, and Questions

The flavonoid silymarin extracted from the seeds of Sylibum marianum is a mixture of 6 flavolignan isomers. The 3 more important isomers are silybin (or silibinin), silydianin, and silychristin. Silybin is functionally the most active of these compounds. This group of flavonoids has been extensively studied and they have been used as hepato-protective substances for the mushroom Amanita phalloides intoxication and mainly chronic liver diseases such as alcoholic cirrhosis and nonalcoholic fatty liver. Hepatitis C progression is not, or slightly, modified by silymarin. Recently, it has also been proposed for SARS COVID-19 infection therapy. The biochemical and molecular mechanisms of action of these substances in cancer are subjects of ongoing research. Paradoxically, many of its identified actions such as antioxidant, promoter of ribosomal synthesis, and mitochondrial membrane stabilization, may seem protumoral at first sight, however, silymarin compounds have clear anticancer effects. Some of them are: decreasing migration through multiple targeting, decreasing hypoxia inducible factor-1α expression, inducing apoptosis in some malignant cells, and inhibiting promitotic signaling among others. Interestingly, the antitumoral activity of silymarin compounds is limited to malignant cells while the nonmalignant cells seem not to be affected. Furthermore, there is a long history of silymarin use in human diseases without toxicity after prolonged administration. The ample distribution and easy accessibility to milk thistle-the source of silymarin compounds, its over the counter availability, the fact that it is a weed, some controversial issues regarding bioavailability, and being a nutraceutical rather than a drug, has somehow led medical professionals to view its anticancer effects with skepticism. This is a fundamental reason why it never achieved bedside status in cancer treatment. However, in spite of all the antitumoral effects, silymarin actually has dual effects and in some cases such as pancreatic cancer it can promote stemness. This review deals with recent investigations to elucidate the molecular actions of this flavonoid in cancer, and to consider the possibility of repurposing it. Particular attention is dedicated to silymarin's dual role in cancer and to some controversies of its real effectiveness.

Lung Cancer Management with Silibinin: A Historical and Translational Perspective

The flavonolignan silibinin, the major bioactive component of the silymarin extract of Silybum marianum (milk thistle) seeds, is gaining traction as a novel anti-cancer therapeutic. Here, we review the historical developments that have laid the groundwork for the evaluation of silibinin as a chemopreventive and therapeutic agent in human lung cancer, including translational insights into its mechanism of action to control the aggressive behavior of lung carcinoma subtypes prone to metastasis. First, we summarize the evidence from chemically induced primary lung tumors supporting a role for silibinin in lung cancer prevention. Second, we reassess the preclinical and clinical evidence on the effectiveness of silibinin against drug resistance and brain metastasis traits of lung carcinomas. Third, we revisit the transcription factor STAT3 as a central tumor-cell intrinsic and microenvironmental target of silibinin in primary lung tumors and brain metastasis. Finally, by unraveling the selective vulnerability of silibinin-treated tumor cells to drugs using CRISPR-based chemosensitivity screenings (e.g., the hexosamine biosynthesis pathway inhibitor azaserine), we illustrate how the therapeutic use of silibinin against targetable weaknesses might be capitalized in specific lung cancer subtypes (e.g., KRAS/STK11 co-mutant tumors). Forthcoming studies should take up the challenge of developing silibinin and/or next-generation silibinin derivatives as novel lung cancer-preventive and therapeutic biomolecules.

Perspectives and controversies regarding the use of natural products for the treatment of lung cancer

Lung cancer is the leading cause of cancer‐related mortality both in men and women and accounts for 18.4% of all cancer‐related deaths. Although advanced therapy methods have been developed, the prognosis of lung cancer patients remains extremely poor. Over the past few decades, clinicians and researchers have found that chemical compounds extracted from natural products may be useful for treating lung cancer. Drug formulations derived from natural compounds, such as paclitaxel, doxorubicin, and camptothecin, have been successfully used as chemotherapeutics for lung cancer. In recent years, hundreds of new natural compounds that can be used to treat lung cancer have been found through basic and sub‐clinical research. However, there has not been a corresponding increase in the number of drugs that have been used in a clinical setting. The probable reasons may include low solubility, limited absorption, unfavorable metabolism, and severe side effects. In this review, we present a summary of the natural compounds that have been proven to be effective for the treatment of lung cancer, as well as an understanding of the mechanisms underlying their pharmacological effects. We have also highlighted current controversies and have attempted to provide solutions for the clinical translation of these compounds.

Inhibitory Effect of Black Radish (Raphanus sativus L. var. niger) Extracts on Lipopolysaccharide-Induced Inflammatory Response in the Mouse Monocyte/Macrophage-Like Cell Line RAW 264.7

Black radish (Raphanus sativus L. var. niger), which is cultivated worldwide, is used in traditional medicine as it aids liver function, gastric secretion, gallbladder function, and gallstone mitigation. In this study, we examined the anti-inflammatory effects of black radish extract (BRE) on the lipopolysaccharide (LPS)- and interleukin (IL)-6-mediated inflammatory responses in the RAW 264.7 cell lines. Our findings show that BRE significantly ameliorated LPS-induced nitric oxide (NO) release and production of pro-inflammatory cytokines, such as IL-1β, IL-6, tumor necrosis factor (TNF)-α, and prostaglandin E2. The levels of cyclooxygenase (COX)-2 and inducible NO synthase (iNOS) in LPS-stimulated RAW 264.7 cells were found to be suppressed by BRE. Further, BRE significantly suppressed the LPS-induced expression of mRNAs encoding COX-2, iNOS, IL-1β, IL-6, and TNF-α in a concentration-dependent manner. BRE treatment significantly inhibited Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) phosphorylation in IL-6- and LPS-treated RAW 264.7 cells. In addition, BRE decreased the levels of phosphorylated extracellular signal-regulated protein kinases and c-Jun N-terminal kinase under the same conditions. Moreover, BRE induced high nuclear factor erythroid 2-related factor 2 (NRF2) levels and its target gene heme oxygenase 1 (HO-1) in the absence of LPS. These data demonstrate that BRE may be beneficial for treating inflammation through selective immunomodulatory effects, which may be mediated by inhibition of the STAT3/JAK2 and activation of the NRF2/HO-1 signal transduction pathways.

Dendrobium nobile Alkaloids Protects against H2O2-Induced Neuronal Injury by Suppressing JAK-STATs Pathway Activation in N2A Cells

The purpose of this study was to investigate the preventive effect and mechanism of Dendrobium alkaloids (DNLA) on oxidative stress-related death in neuronal cells. Our results demonstrated that DNLA has a direct neuroprotective effect through oxidative stress in N2A cells induced by hydrogen peroxide (H₂O₂). CCK8, lactate dehydrogenase (LDH), intracellular Ca²⁺, intracellular reactive oxygen species (ROS), and mitochondrial membrane potential (MMP) were used to evaluate the mechanism of DNLA neutralization by H₂O₂-induced injury. Results presented in the paper indicate that treatment with DNLA (35 ng/mL) significantly attenuated decreases in cell viability, release of LDH, and apoptosis after H₂O₂-induced neuronal injury. Furthermore, DNLA significantly reduced intracellular Ca²⁺ up-regulation, ROS production, and inhibited mitochondrial depolarization. Moreover, DNLA treatment significantly downregulated expressions of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6, nitric oxide synthase, janus kinase-signal transducer and activators of transcription (JAK-STATs) signaling in N2A cells, all of which were H₂O₂-induced. Taken together, our findings suggested that DNLA may inhibit the expression of pro-inflammatory and pro-apoptotic factors by blocking JAK-STATs signaling after oxidative stress injury. This research provides a potential experimental basis for further application of DNLA to prevent various human nervous system diseases caused by oxidative stress.

Silibinin and SARS-CoV-2: Dual Targeting of Host Cytokine Storm and Virus Replication Machinery for Clinical Management of COVID-19 Patients

COVID-19, the illness caused by infection with the novel coronavirus SARS-CoV-2, is a rapidly spreading global pandemic in urgent need of effective treatments. Here we present a comprehensive examination of the host- and virus-targeted functions of the flavonolignan silibinin, a potential drug candidate against COVID-19/SARS-CoV-2. As a direct inhibitor of STAT3—a master checkpoint regulator of inflammatory cytokine signaling and immune response—silibinin might be expected to phenotypically integrate the mechanisms of action of IL-6-targeted monoclonal antibodies and pan-JAK1/2 inhibitors to limit the cytokine storm and T-cell lymphopenia in the clinical setting of severe COVID-19. As a computationally predicted, remdesivir-like inhibitor of RNA-dependent RNA polymerase (RdRp)—the central component of the replication/transcription machinery of SARS-CoV-2—silibinin is expected to reduce viral load and impede delayed interferon responses. The dual ability of silibinin to target both the host cytokine storm and the virus replication machinery provides a strong rationale for the clinical testing of silibinin against the COVID-19 global public health emergency. A randomized, open-label, phase II multicentric clinical trial (SIL-COVID19) will evaluate the therapeutic efficacy of silibinin in the prevention of acute respiratory distress syndrome in moderate-to-severe COVID-19-positive onco-hematological patients at the Catalan Institute of Oncology in Catalonia, Spain.

Anti-Inflammatory Effects of Bee Venom on Phthalic Anhydride-Induced Atopic Dermatitis

Background: Atopic dermatitis (AD) is a chronic inflammatory condition which can be studied using phthalic anhydride (PA) to induce AD. Anti-inflammatory properties of bee venom (BV) wereinvestigated to determine whether it may be a useful treatment for AD.Methods: AD was induced by applying to pical PA to 8-week-old HR-1 mice (<i>N</i> = 50), then treating with (0.1, 0.25, and 0.5 ?g) or without topical BV. Body weight, ear thickness histology, enzymelinked immune sorbent assay (serum IgE concentrations), Western blot analysis [inducible nitric oxide synthase, cyclooxygenase-2, IκB-α, phospho-IκB-α, c-Jun N-terminal kinase (JNK), phosphoJNK, p38, phospho-p38, extra cellular signal-regulated kinase (ERK), and phospho-ERK], and the pull down assay for immunoblotting (p50), were used to measure inflammatory mediators.Results: PA + BV (0.1, 0.25, and 0.5 μg) significantly decreased ear thickness without altering body weight. IgE concentrations decreased in the PA + BV (0.5 ?g)-treated groups compared with PAtreatment. Tumor necrosis factor-α, interleukin-1β, inducible nitric oxide synthase, cyclooxygenase-2, phospho-IκB-α, phospho-JNK, p38, phospho-p38, and phospho-ERK, all decreased following treatment with PA + BV compared with the PA-treatment alone. p50 was upregulated in the PA + BV-treated groups compared with the PA-treated group. Furthermore, the number of mast cells decreased in the PA + BV-treated groups compared with the PA-treated group. Epidermal thickness was significantly lower in the PA + BV-treated group compared with PA treatment alone.Conclusion: BV maybe a useful anti-inflammatory treatment for AD.

Inhibitory effect of Carnosol on UVB-induced inflammation via inhibition of STAT3

Ultraviolet B (UVB) irradiation causes sunburn, inflammatory responses, dysregulation of immune function, oxidative stress, DNA damage and photocarcinogenesis on skin. Rosemary (Rosmarinus officinalis L.) has been reported to inhibit inflammation. Carnosol, a major component of Rosemary, has prominent anti-inflammatory effects. However, its protective effect on UVB-induced inflammatory skin responses has not yet been reported. Here, we investigated the effectiveness of carnosol on UVB-induced inflammation. We examined the anti-inflammation effect of topical application of carnosol (0.05 µg/cm²) on UVB (540 mJ/cm², for 3 successive days)-induced skin inflammation in HR1 mice. Topical application of carnosol inhibited UVB-induced erythema, epidermal thickness, inflammatory responses in HR1 mice. Carnosol reduced the level of Immunoglobulin-E and IL-1β in blood serum of UVB-induced mice. Carnosol also significantly inhibited the UVB-induced expression of inflammatory marker protein (iNOS and COX-2) in back skin of mice. In addition, carnosol treated skin decreased activation of STAT3, a transcriptional factor regulating inflammatory genes. Our study suggested that carnosol has protective effects on skin inflammatory skin damages by UVB.

COX-2 metabolic products, the prostaglandin I2 and F2α, mediate the effects of TNF-α and Zn2+ in stimulating the phosphorylation of Tau

Although the roles of cyclooxygenase-2 (COX-2) and prostaglandins (PGs) in regulating amyloid precursor protein (APP) cleavage and β-amyloid protein (Aβ) production have been the subjects of numerous investigations, their effects on tau phosphorylation have been largely overlooked. Using human Tau^P301S transgenic (Tg) mice as in vivo model, our results demonstrated that PGI₂ and PGF_2α mediated the effects of tumor necrosis factor α (TNF-α) and Zinc ions (Zn²⁺) on upregulating the phosphorylation of tau via the PI3-K/AKT, ERK1/2 and JNK/c-Jun signaling pathways. Specifically, we initially found that high level of Zn²⁺ upregulates the expression of COX-2 via stimulating the activity of TNF-α in a zinc transporter 3 (ZnT3)-dependent mechanism. COX-2 upregulation then stimulates the phosphorylation of tau at both Ser 202 and Ser 400/Thr 403/Ser 404 via PGI₂ and F_2α treatment either in i.c.v.-injected mice or in n2a cells. Using n2a cells as in vitro model, we further revealed critical roles for the PI3-K/AKT, ERK1/2 and JNK/c-Jun pathways in mediating the effects of PGI₂ and F_2α in the phosphorylation of tau. Finally, NS398 treatment delayed the onset of cognitive decline in Tau^P301S Tg mice according to the nest construction or limb clasping test.

Inhibitory Effect of Carnosol on Phthalic Anhydride-Induced Atopic Dermatitis via Inhibition of STAT3

Carnosol is a phenolic antioxidant present in rosemary (Rosmarinus officinalis). It is known for anti-inflammatory effects, analgesic activity and anti-cancer effects. However, no study has been dedicated yet to its effect on atopic dermatitis (AD). Here, we show that carnosol effectively inhibited LPS-induced nitric oxide (NO) generation and expression of inflammatory marker proteins (iNOS and COX-2) in RAW 264.7 cells. In addition, carnosol effectively inhibits the phosphorylation of STAT3 and DNA binding activity in RAW 264.7 cells. Pull down assay and docking model analysis showed that carnosol directly binds to the DNA binding domain (DBD) of STAT3. We next examined the anti-atopic activity of carnosol (0.05 µg/cm²) using 5% Phthalic anhydride (PA)-induced AD model in HR1 mice. Carnosol treatment significantly reduced 5% PA-induced AD like skin inflammation in skin tissues compared with control mice. Moreover, carnosol treatment inhibits the expression of iNOS and COX-2 in skin tissue. In addition, the levels of TNF-α, IL-1β, and Immunoglobulin-E in blood serum was significantly decreased in carnosol treated mice compared with those of 5% PA treated group. Furthermore, the activation of STAT3 in skin tissue was decreased in carnosol treated mice compared with control mice. In conclusion, these findings suggest that carnosol exhibited a potential anti-AD activity by inhibiting pro-inflammatory mediators through suppression of STAT3 activation via direct binding to DBD of STAT3.

Silibinin downregulates MMP2 expression via Jak2/STAT3 pathway and inhibits the migration and invasive potential in MDA-MB-231 cells

Worldwide, breast cancer (BCa) is the most common cancer in women. Among its subtypes, triple-negative breast cancer (TNBC) is an aggressive form associated with diminished survival. TNBCs are characterized by their absence, or minimal expression, of the estrogen and progesterone receptors, as well as the human epidermal growth factor receptor 2 (i.e. ER-/-, PR-/-, Her2-/Low). Consequently, treatment for this subtype of BCa remains problematic. Silibinin, a derivative of the flavonoid silymarin, is reported to have anticancer activities against hepatic and non-small cell lung cancers. We hypothesized that silibinin might inhibit cell-extracellular matrix interactions via the regulation, expression, and activation of STAT3 in TNBCs, which could directly inhibit metastasis in silibinin-treated BCa cells. Using proliferation assays, we found that exposure to silibinin at a concentration of 200 µM inhibited the proliferation of breast cancer (BCa) cells; this concentration also inhibited phosphorylation of STAT3 and its principal upstream kinase, Jak2. Furthermore, we found that silibinin inhibited the nuclear translocation of STAT3, as well as its binding to the MMP2 gene promoter. The ability of silibinin to inhibit metastasis was further studied using an in vitro invasion assay. The results confirm the role of STAT3 as a critical mediator in the invasive potential of BCa cells, and STAT3 knock-down resulted in inhibition of invasion. The invasion ability of silibinin-treated BCa cells was studied in detail with the expression of MMP2. Prevention of STAT3 activation also resulted in the inhibition of MMP2 expression. Use of a small interfering RNA to knock down STAT3 (siSTAT3) allowed us to confirm the role of STAT3 in regulating MMP2 expression, as well as the mechanism of action of silibinin in inhibiting MMP2. Taken together, we found that silibinin inhibits the Jak2/STAT3/MMP2 signaling pathway, and inhibits the proliferation, migration, and invasion of triple-negative BCa cells.

Mechanistic Study of the Inhibitory Effect of Kaempferol on Uterine Fibroids In Vitro

Background

This study examined the effect of kaempferol on uterine fibroids in vitro and the underlying mechanism, and investigated the potential of kaempferol as a clinical drug for the treatment of uterine fibroids.

Material/Methods

Uterine fibroid tissue and surrounding smooth muscle tissue were collected for primary culture. Different concentrations of kaempferol (12 μM, 24 μM, and 48 μM) were used to treat the cells for 24, 48, and 72 hours. Ethanol was used in the control group. A CCK-8 colorimetric assay was used to detect cell proliferation. Real-time PCR and immunoblot were used to detect estrogen receptor (ER), insulin-like growth factor-1 (IGF-1), and vascular endothelial growth factor (VEGF) levels in mRNA and protein.

Results

The differences in proliferation at different time points and concentrations of kaempferol were statistically significant. The inhibitory effect of kaempferol on mRNA levels of ER and IGF, and protein levels of ER, VEGF, and IGF-1 were positively correlated with kaempferol concentration. Changes in kaempferol concentration showed no effect on VEGF mRNA expression. Treatment with kaempferol significantly lowered myocardin levels in uterine fibroid tissue compared to normal uterine smooth muscle (P<0.05).

Conclusions

Kaempferol might be used for clinical treatment of uterine fibroids due to its inhibitory effect on the proliferation of uterine fibroids cells.

A tryptamine-paeonol hybridization compound inhibits LPS-mediated inflammation in BV2 cells

In the present study, we synthesized and evaluated the anti-inflammatory effects of three tryptamine (Trm) hybrid compounds, HBU-375, HBU-376 and HBU-379. The Click reaction between the azido-Trm and 2- or 4-propazylated paeonol moiety resulted in HBU-376 and HBU-375, respectively. HBU-379 was generated by hybridizing Trm with propazylated acetyl-syringic acid. HBU-376 and HBU-375 dose-dependently inhibited LPS and caused nitric oxide (NO) generation in BV2 cells, whereas HBU-379 minimally inhibited NO generation, indicating that the paeonol unit plays an important role in the anti-inflammatory effect of Trm hybrid compounds. Although HBU-375 and HBU-376 demonstrated a similar inhibitory effect on LPS-induced NO generation, HBU-376 resulted in less cellular toxicity presumably due to the free phenolic hydroxyl group of paeonol. Therefore, HBU-376 may be a promising anti-inflammatory agent conferring minimal cytotoxicity. HBU-376 significantly and dose-dependently inhibited LPS-induced NO products, NO synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-6, MCP-1 and interleukin-1β mRNA expressions and iNOS and COX-2 protein expressions. However, at the same concentrations, Trm or paeonol individually did not inhibit LPS-mediated production of inflammatory molecules. HBU-376 inhibited both LPS-induced STAT-3 phosphorylation and nuclear factor-kappa B (NF-κB) activation. Furthermore, LPS-mediated DNA binding of c-Rel, p50 and p52 to the NF-κB binding site of the iNOS promoter was inhibited by HBU-376, whereas Trm and paeonol did not inhibit LPS-induced NF-κB activation and DNA binding of c-Rel, p50 and p52. Overall, our data suggest that the Trm-paeonol hybrid compound down-regulates inflammatory responses by inhibiting NF-κB and NF-κB-dependent gene expression. This suggests that it is a potential therapeutic agent for inflammatory diseases of the central nervous system.

miR-101 inhibits glioma cell invasion via the downregulation of COX-2

Glioma is the most common type of primary tumor of the central nervous system. The present study aimed to demonstrate the role of miR-101 and cyclooxygenase-2 (COX-2) in the initiation and development of glioma. The expression of miR-101 and COX-2 in normal and malignant human glial cells and tissues was determined by western blotting and quantitative polymerase chain reaction analysis. The role of miR-101 on COX-2 expression was evaluated by a dual-luciferase reporter assay. The effects of miR-101 and COX-2 in glioma cell proliferation and invasion was verified by CCK-8 test and Transwell assays, respectively. The present study demonstrated that miR-101 expression was downregulated while COX-2 was upregulated in glioma tissues and cells. Furthermore, transfection of miR-101 significantly downregulated COX-2 expression in both U373 and U87 glioma cells. In addition, further experiments revealed that overexpression of miR-101 resulted in significant inhibition of the in vitro proliferation and migration of glioma cells, and the in vivo growth of established tumors. Direct downregulation of COX-2 by transfection with corresponding small interfering RNA also inhibited the proliferation and invasion of glioma cells. These results indicate that downregulation of miR-101 is involved in the initiation and development of glioma via COX-2 upregulation.

The ubiquitin-like modifier FAT10 in cancer development

During the last years it has emerged that the ubiquitin-like modifier FAT10 is directly involved in cancer development. FAT10 expression is highly up-regulated by pro-inflammatory cytokines IFN-γ and TNF-α in all cell types and tissues and it was also found to be up-regulated in many cancer types such as glioma, colorectal, liver or gastric cancer. While pro-inflammatory cytokines within the tumor microenvironment probably contribute to FAT10 overexpression, an increasing body of evidence argues that pro-malignant capacities of FAT10 itself largely underlie its broad and intense overexpression in tumor tissues. FAT10 thereby regulates pathways involved in cancer development such as the NF-κB- or Wnt-signaling. Moreover, FAT10 directly interacts with and influences downstream targets such as MAD2, p53 or β-catenin, leading to enhanced survival, proliferation, invasion and metastasis formation of cancer cells but also of non-malignant cells. In this review we will provide an overview of the regulation of FAT10 expression as well as its function in carcinogenesis.

Physiological, Tumor, and Metastatic Niches: Opportunities and Challenges for Targeting the Tumor Microenvironment

The primary tumor niche and the related but distinct premetastatic/metastatic niche comprise a number of essential players, including immune cells, stromal cells, and extracellular matrix. The cross-talk between these components is key to tumor progression. Many of these cell types and signaling pathways in the tumor microenvironment also are found in physiological and stem cell niches, such as the bone marrow, colonic crypt, and skin bulge. Here they play tightly regulated roles in wound healing and tissue homeostasis. Understanding the similarities and differences between these distinct niches may better inform our ability to therapeutically target the tumor microenvironment. In this review we discuss a number of tumor and metastatic niche components as they relate to stem cell niches and highlight potential therapeutic strategies in pediatric cancers.

Signaling factors and pathways of α-particle irradiation induced bilateral bystander responses between Beas-2B and U937 cells

Although radiation induced bystander effects (RIBE) have been investigated for decades for their potential health risk, the underlying gene regulation is still largely unclear, especially the roles of immune system and inflammatory response in RIBE. In the present study, macrophage U937 cells and epithelial Beas-2B cells were co-cultured to disclose the cascades of bystander signaling factors and intercellular communications. After α-particle irradiation, both ERK and p38 pathways were activated in Beas-2B cells and were associated with the autocrine and paracrine signaling of TNF-α and IL-8, resulting in direct damage to the irradiated cells. Similar upregulation of TNF-α and IL-8 was induced in the bystander U937 cells after co-culture with α-irradiated Beas-2B cells. This upregulation was dependent on the activation of NF-κB pathway and was responsible for the enhanced damage of α-irradiated Beas-2B cells. Interestingly, the increased expressions of TNF-α and IL-8 mRNAs in the bystander U937 cells were clearly relayed on the activated ERK and p38 pathways in the irradiated Beas-2B cells, and the upregulation of TNF-α and IL-8 mRNAs in co-cultured Beas-2B cells was also partly due to the activated NF-κB pathway in the bystander U937 cells. With the pretreatment of U0126 (MEK1/2 inhibitor), SB203580 (p38 inhibitor) or BAY 11-7082 (NF-κB inhibitor), the aggravated damage in the α-irradiated Beas-2B cells could be largely alleviated. Our results disclosed novel signaling cascades of macrophage-mediated bilateral bystander responses that the release of TNF-α and IL-8 regulated by MAPK and NF-κB pathways synergistically increased cellular injury after α-particle irradiation.

Phytomedicine polypharmacology: Cancer therapy through modulating the tumor microenvironment and oxylipin dynamics

Integrative approaches in cancer therapy have recently been extended beyond the induction of cytotoxicity to controlling the tumor microenvironment and modulating inflammatory cascades and pathways such as lipid mediator biosynthesis and their dynamics. Profiling of important lipid messengers, such as oxylipins, produced as part of the physiological response to pharmacological stimuli, provides a unique opportunity to explore drug pharmacology and the possibilities for molecular management of cancer physiopathology. Whereas single targeted chemotherapeutic drugs commonly lack efficacy and invoke drug resistance and/or adverse effects in cancer patients, traditional herbal medicines are seen as bright prospects for treating complex diseases, such as cancers, in a systematic and holistic manner. Understanding the molecular mechanisms of traditional medicine and its bioactive chemical constituents may aid the modernization of herbal remedies and the discovery of novel phytoagents for cancer management. In this review, systems-based polypharmacology and studies to develop multi-target drugs or leads from phytomedicines and their derived natural products that may overcome the problems of current anti-cancer drugs, are proposed and summarized.

Silibinin down-regulates FAT10 and modulate TNF-α/IFN-γ-induced chromosomal instability and apoptosis sensitivity

Pleiotropic pro-inflammatory cytokines, TNF-α and IFN-γ (TI), play important yet diverse roles in cell survival, proliferation, and death. Recent evidence highlights FAT10 as a downstream molecule in the pathway of inflammation-induced tumorigenesis through mediating the effect of cytokines in causing numerical CIN and protecting cells from cytokines-induced cell death. cDNA microarray analysis of cells treated with TI revealed 493 deregulated genes with FAT10 being the most up-regulated (85.7-fold) gene and NF-κB being the key nodal hub of TI-response genes. Silibinin is reported to be a powerful antioxidant and has anti-C effects against various carcinomas by affecting various signaling molecules/pathways including MAPK, NF-κB and STATs. As NF-κB signaling pathway is a major mediator of the tumor-promoting activities of TI, we thus examine the effects of silibinin on TI-induced FAT10 expression and CIN. Our data showed that silibinin inhibited expression of FAT10, TI-induced chromosome instability (CIN) as well as sensitizes cells to TI-induced apoptosis. Significantly, silibinin suppressed intra-tumorally injected TNF-α-induced tumor growth. This represents the first report associating silibinin with FAT10 and demonstrating that silibinin can modulate TI-induced CIN, apoptosis sensitivity and suppressing TNF-α-induced tumor growth.

Micro ribonucleic acid (RNA)-101 inhibits cell proliferation and invasion of lung cancer by regulating cyclooxygenase-2

Background

Micro ribonucleic acid (miR-101) can regulate the expression of cyclooxygenase-2 (COX-2) and participate in the pathogenesis of malignant tumors. This study investigates the effects of miRNA-101 and COX-2 in lung cancer and the impact of miR-101 on the proliferation and invasion of human lung cancer A549 cell line.

Methods

The expression of miR-101 in 20 separate lung cancer tissues was detected by real time polymerase chain reaction; COX-2 expression was also detected. A549 cells were transfected with miR-101 or negative control oligonucleotide duplex mimic (miR-NC). In vivo tumorigenesis abilities were detected in localized human lung cancer xeno-transplant models in BALB/c nude mice.

Results

MiR-101 expression was significantly lower and the level of COX-2 significantly higher in lung cancer tissues than in adjacent parenchyma (2.918 ± 1.006 vs. 5.953 ± 1.976, P = 0.001; 0.887 ± 0.260 vs. 0.355 ± 0.156, P = 0.001, respectively). Correlation analysis revealed that miR-101 negatively correlated with COX-2 in lung cancer tissues (R = −0.596, P = 0.002). Compared with A549-miR-NC cells, the expression of COX-2 was significantly decreased in A549 cells transfected with miR-101 (P < 0.001). The proliferation of A549 cells was markedly inhibited after transfection of miR-101. The in vivo tumor growth of A549 cells transfected with miR-101 was significantly slower than wide type A549 cells.

Conclusion

MiR-101 expression is decreased in lung cancer, inducing an increase in COX-2 level. Enforced expression of miR-101 can remarkably reduce the cell proliferation and invasion ability of lung cancer cells.

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.

Data mining of atherosclerotic plaque transcriptomes predicts STAT1-dependent inflammatory signal integration in vascular disease

Atherosclerotic plaque development involves multiple extra- and intra-cellular signals engaging cells from the immune system and from the vasculature. Pro-inflammatory pathways activated by interferon gamma (IFNγ) and toll-like receptor 4 (TLR4) ligands are profoundly involved in plaque formation and have been shown to involve cross-talk in all atheroma-interacting cell types leading to increased activation of signal transducer and activator of transcription-1 (STAT1) and elevated expression of pro-inflammatory mediators. Here we demonstrate that in Gene Expression Omnibus repository (GEO) deposited microarray datasets, obtained from human coronary and carotid atherosclerotic plaques, a significant increase in expression of pro-inflammatory and immunomodulatory genes can be detected. Moreover, increased expression of multiple chemokines, adhesion molecules and matrix-remodeling molecules was commonly detected in both plaque types and correlated with the presence of putative STAT1 binding sites in their promoters, suggesting strong involvement of STAT1 in plaque development. We also provide evidence to suggest that STAT1-nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) or STAT1-interferon-regulated factor (IRF) regulatory modules are over-represented in the promoters of these inflammatory genes, which points to a possible contribution of IFNγ and TLR4 cross-talk in the process of atherogenesis. Finally, a subset of these genes encodes for secreted proteins that could serve as a basis of a non-invasive diagnostic assay. The results of our in silico analysis in vitro provide potential evidence that STAT1-dependent IFNγ-TLR4 cross-talk plays a crucial role in coronary and carotid artery plaque development and identifies a STAT1-dependent gene signature that could represent a novel diagnostic tool to monitor and diagnose plaque progression in human atherosclerosis.

Association of recent exposure to ambient metals on fractional exhaled nitric oxide in 9-11 year old inner-city children

Exposure to ambient metals in urban environments has been associated with wheeze, and emergency room visits and hospitalizations due to respiratory illness. However, the effect of ambient metals exposure on airway inflammation, and how these associations may be modified by seroatopy, has not been determined. Fractional exhaled nitric oxide (FENO) is a reliable proxy marker of airway inflammation. We hypothesized that recent ambient concentrations of Ni, V, Zn and Fe would be associated differentially with proximal and distal fractions of exhaled NO, and that these associations would be modified by seroatopy. As part of the Columbia Center for Children's Environmental Health (CCCEH) birth cohort study, 9-11 year old children (n=192) were evaluated. Ambient measures of Ni, V, Zn and Fe were obtained from a local central monitoring site and averaged over 9 days based on three 24h measures every third day. Fractional exhaled nitric oxide (FENO) samples were obtained at constant flows of 50 (FENO50), 83 and 100mL/s, and used to determine surrogate measures for proximal (JNO) and alveolar (Calv) inflammation. Seroatopy was determined by specific IgE at age 7. Data were analyzed using multivariable linear regression. Ambient V and Fe concentrations were associated positively with FENO50 (p=0.018, p=0.027). Ambient Fe was associated positively with JNO (p=0.017). Ambient Ni and V concentrations were associated positively with Calv (p=0.004, p=0.018, respectively). A stronger association of Ni concentrations with Calv was observed among the children with seroatopy. These results suggest that ambient metals are associated differentially with different fractions of FENO production, and this relationship may be modified by seroatopy.

TNF-α induces cytosolic phospholipase A2 expression via Jak2/PDGFR-dependent Elk-1/p300 activation in human lung epithelial cells

Cytosolic phospholipase A2 (cPLA2) plays a pivotal role in mediating agonist-induced arachidonic acid release for prostaglandin (PG) synthesis during inflammation triggered by tumor necrosis factor-α (TNF-α). However, the mechanisms underlying TNF-α-induced cPLA2 expression in human lung epithelial cells (HPAEpiCs) were not completely understood. Here, we demonstrated that TNF-α induced cPLA2 mRNA and protein expression, promoter activity, and PGE2 secretion in HPAEpiCs. These responses induced by TNF-α were inhibited by pretreatment with the inhibitor of Jak2 (AG490), platelet-derived growth factor receptor (PDGFR) (AG1296), phosphoinositide 3 kinase (PI3K) (LY294002), or MEK1/2 (PD98059) and transfection with siRNA of Jak2, PDGFR, Akt, or p42. We showed that TNF-α markedly stimulated Jak2, PDGFR, Akt, and p42/p44 MAPK phosphorylation, which were attenuated by their respective inhibitors. Moreover, TNF-α stimulated Akt activation via a Jak2/PDGFR pathway in HPAEpiCs. In addition, TNF-α-induced p42/p44 MAPK phosphorylation was reduced by AG1296 or LY294002. On the other hand, TNF-α could induce Akt and p42/p44 MAPK translocation from the cytosol into the nucleus, which was inhibited by AG490, AG1296, or LY294002. Finally, we showed that TNF-α stimulated Elk-1 phosphorylation, which was reduced by LY294002 or PD98059. We also observed that TNF-α time dependently induced p300/Elk-1 and p300/Akt complex formation in HPAEpiCs, which was reduced by AG490, AG1296, or LY294002. The activity of cPLA2 protein upregulated by TNF-α was reflected on the PGE2 release, which was reduced by AG490, AG1296, LY294002 , or PD98059. Taken together, these results demonstrated that TNF-α-induced cPLA2 expression and PGE2 release were mediated through a Jak2/PDGFR/PI3K/Akt/p42/p44 MAPK/Elk-1 pathway in HPAEpiCs.

Targeting tumor microenvironment with silibinin: promise and potential for a translational cancer chemopreventive strategy

Tumor microenvironment (TME) refers to the dynamic cellular and extra-cellular components surrounding tumor cells at each stage of the carcinogenesis. TME has now emerged as an integral and inseparable part of the carcinogenesis that plays a critical role in tumor growth, angiogenesis, epithelial to mesenchymal transition (EMT), invasion, migration and metastasis. Besides its vital role in carcinogenesis, TME is also a better drug target because of its relative genetic stability with lesser probability for the development of drug-resistance. Several drugs targeting the TME (endothelial cells, macrophages, cancer-associated fibroblasts, or extra-cellular matrix) have either been approved or are in clinical trials. Recently, non-steroidal anti-inflammatory drugs targeting inflammation were reported to also prevent several cancers. These exciting developments suggest that cancer chemopreventive strategies targeting both tumor and TME would be better and effective towards preventing, retarding or reversing the process of carcinogenesis. Here, we have reviewed the effect of a well established hepatoprotective and chemopreventive agent silibinin on cellular (endothelial, fibroblast and immune cells) and non-cellular components (cytokines, growth factors, proteinases etc.) of the TME. Silibinin targets TME constituents as well as their interaction with cancer cells, thereby inhibiting tumor growth, angiogenesis, inflammation, EMT, and metastasis. Silibinin is already in clinical trials, and based upon completed studies we suggest that its chemopreventive effectiveness should be verified through its effect on biological end points in both tumor and TME. Overall, we believe that the chemopreventive strategies targeting both tumor and TME have practical and translational utility in lowering the cancer burden.

Chemopreventive and anti-cancer efficacy of silibinin against growth and progression of lung cancer

The use of systemic chemotherapeutic drugs and molecular-targeted therapies in the treatment of patients with locally advanced or metastatic lung cancer has its limitations due to the associated acute and cumulative dose limiting toxicities and acquisition of drug resistance. Prevention and therapeutic intervention by dietary agents including nutraceuticals which are non-toxic, cost-effective, and physiologically bioavailable, are emerging approaches in lung cancer management. In this regard, silibinin, a natural flavonolignan, has been rigorously evaluated for the prevention and growth control of lung cancer through extensive in vitro and in vivo studies. Successful studies conducted so far, have established that silibinin is effective both alone and in combination with other agents (e.g., chemotherapeutic and epigenetic agents) in significantly inhibiting the growth of lung cancer cells. In vivo, its effects have been shown to be mediated through inhibition of proliferation, angiogenesis and epigenetic-related events. Therefore, the present review focuses on encompassing the efficacy and mechanisms of silibinin against lung cancer.

Procyanidin B2 3,3(″)-di-O-gallate, a biologically active constituent of grape seed extract, induces apoptosis in human prostate cancer cells via targeting NF-κB, Stat3, and AP1 transcription factors

Recently, we identified procyanidin B2 3,3(″)-di-O-gallate (B2G2) as most active constituent of grape seed extract (GSE) for efficacy against prostate cancer (PCa). Isolating large quantities of B2G2 from total GSE is labor intensive and expensive, thereby limiting both efficacy and mechanistic studies with this novel anticancer agent. Accordingly, here we synthesized gram-scale quantities of B2G2, compared it with B2G2 isolated from GSE for possible equivalent biological activity and conducted mechanistic studies. Both B2G2 preparations inhibited cell growth, decreased clonogenicity, and induced cell cycle arrest and apoptotic death, comparable to each other, in various human PCa cell lines. Mechanistic studies focusing on transcription factors involved in apoptotic and survival pathways revealed that B2G2 significantly inhibits NF-κB and activator protein1 (AP1) transcriptional activity and nuclear translocation of signal transducer and activator of transcription3 (Stat3) in PCa cell lines, irrespective of their functional androgen receptor status. B2G2 also decreased survivin expression which is regulated by NF-κB, AP1, and Stat3 and increased cleaved PARP level. In summary, we report B2G2 chemical synthesis at gram-quantity with equivalent biological efficacy against human PCa cell lines and same molecular targeting profiles at key transcription factors level. The synthetic B2G2 will stimulate more research on prostate and possibly other malignancies in preclinical models and clinical translation.

Treated effect of silymarin on vascular function of aged rats: Dependant on nitric oxide pathway

Abstract Context: Aging leads to endothelial dysfunction and vascular stiffness which are the main causes of many cardiovascular diseases. Previous reports have shown that the cell protective effect of silymarin (SM) is dependent on its antioxidant properties. Objectives: We investigated the effect of SM on vascular functions of aged rats and the involvement of nitric oxide or cyclooxygenase (COX) activity in this effect. Materials and methods: Isolated rat aortas were obtained from 22-month old rats. Each ring was incubated with SM (50 mg/L), SM/l-nitro-arginine methyl ester (100 μM, l-NAME) or SM/indomethacin (10 μM, INDO) in tissue bath. Three- to four-month-old rats were used as young controls. Endothelium-intact rings were precontracted with α-receptor agonist phenylephrine (0.001-30 µM) or voltage-dependent high potassium (40 mM), endothelium dependent/independent relaxant responses were obtained using acetylcholine (0.001-30 µM) and sodium nitroprusside (0.0001-3 µM), respectively. Results: Aging increased phenylephrine sensitivity (6.45 ± 0.08; 6.88 ± 0.09) and decreased KCl contraction (882 ± 118.4; 499 ± 80.4). SM treatment decreased the Emax of both agents (548 ± 109; 223 ± 48.9). Aging deteriorated acetylcholine relaxation (93.9 ± 2.09; 72.0 ± 2.56) and SM improved the response (86.3 ± 1.90). l-NAME prevented the SM effect whereas INDO was ineffective. Discussion and Conclusion: Immediate SM treatment partially restored endothelial dysfunction and vascular tone in aging. The possible mechanism might not be mediated by prostacyclin or the COX pathway in acute administration; the nitric oxide pathway and calcium antagonistic features of SM relate to its action on the vessel.

Silymarin improves vascular function of aged ovariectomized rats

Both aging and estrogen depletion lead to endothelial dysfunction, which is the main reason of many cardiovascular diseases. Previous reports have shown that cell protective effect of silymarin (SM) depends on its antioxidant and phytoestrogenic properties. We investigated the effect of SM on vascular stiffness of aged menopausal rats and the involvement of estrogenic activity in this effect. Isolated rat aortas were obtained from 22-month-old rats, after 18 months of ovariectomy (OVX) follow-up. Each ring was incubated in tissue bath either with SM (50 mg/L) and 17β-estradiol (10 μM, E2) or in the presence of SM/fulvestrant (50 mg/L, 10 μM). Endothelium-intact rings were precontracted with phenylephrine (0.001-30 μM) or high potassium (40 mM); endothelium-dependent/independent relaxant responses were obtained using acetylcholine (0.001-30 μM) and sodium nitroprusside (0.0001-3 μM), respectively. While phenylephrine sensitivity was significantly increased in OVX rats, relaxations were significantly less in aged OVX rats compared with young rats. In spite of the presence of estrogen antagonist, immediate SM treatment restored the endothelial function and vascular tone better than estrogen replacement. Additionally, as a complementary and alternative medicine, it does not cause estrogenic side effects when taken acutely.

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

Despite advances in early detection, prostate cancer remains the second highest cancer mortality in American men, and even successful interventions are associated with enormous health care costs as well as prolonged deleterious effects on quality of patient life. Prostate cancer chemoprevention is one potential avenue to alleviate these burdens. It is a regime whereby long-term treatments are intended to prevent or arrest cancer development, in contrast to more direct intervention upon disease diagnosis. Based on this intention, cancer chemoprevention generally focuses on the use of nontoxic chemical agents which are well-tolerated for prolonged usage that is necessary to address prostate cancer's multistage and lengthy period of progression. One such nontoxic natural agent is the flavonoid silibinin, derived from the milk thistle plant (Silybum marianum), which has ancient medicinal usage and potent antioxidant activity. Based on these properties, silibinin has been investigated in a host of cancer models where it exhibits broad-spectrum efficacy against cancer progression both in vitro and in vivo without noticeable toxicity. Specifically in prostate cancer models, silibinin has shown the ability to modulate cell signaling, proliferation, apoptosis, epithelial to mesenchymal transition, invasion, metastasis, and angiogenesis, which taken together provides strong support for silibinin as a candidate prostate cancer chemopreventive agent.

Cardioprotective Effects of Quercetin in Cardiomyocyte under Ischemia/Reperfusion Injury

Quercetin, a polyphenolic compound existing in many vegetables, fruits, has antiinflammatory, antiproliferation, and antioxidant effect on mammalian cells. Quercetin was evaluated for protecting cardiomyocytes from ischemia/reperfusion injury, but its protective mechanism remains unclear in the current study. The cardioprotective effects of quercetin are achieved by reducing the activity of Src kinase, signal transducer and activator of transcription 3 (STAT3), caspase 9, Bax, intracellular reactive oxygen species production, and inflammatory factor and inducible MnSOD expression. Fluorescence two-dimensional differential gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) can reveal the differentially expressed proteins of H9C2 cells treated with H₂O₂ or quercetin. Although 17 identified proteins were altered in H₂O₂-induced cells, these proteins such as alpha-soluble NSF attachment protein (α-SNAP), Ena/VASP-like protein (Evl), and isopentenyl-diphosphate delta-isomerase 1 (Idi-1) were reverted by pretreatment with quercetin, which correlates with kinase activation, DNA repair, lipid, and protein metabolism. Quercetin dephosphorylates Src kinase in H₂O₂-induced H9C2 cells and likely blocks the H₂O₂-induced inflammatory response through STAT3 kinase modulation. This probably contributes to prevent ischemia/reperfusion injury in cardiomyocytes.

Silibinin synergizes with histone deacetylase and DNA methyltransferase inhibitors in upregulating E-cadherin expression together with inhibition of migration and invasion of human non-small cell lung cancer cells

Aggressive cancers in the epithelial-to-mesenchymal transition (EMT) phase are characterized by loss of cell adhesion, repression of E-cadherin, and increased cell mobility. Non-small cell lung cancer (NSCLC) differs in basal level of E-cadherin; predominantly exhibiting silenced expression due to epigenetic-related modifications. Accordingly, effective treatments are needed to modulate these epigenetic events that in turn can positively regulate E-cadherin levels. Herein, we investigated silibinin, a natural flavonolignan with anticancer efficacy against lung cancer, either alone or in combination with epigenetic therapies to modulate E-cadherin expression in a panel of NSCLC cell lines. Silibinin combined with HDAC inhibitor Trichostatin A [TSA; 7-[4-(dimethylamino)phenyl]-N-hydroxy-4,6-dimethyl-7-oxohepta-2,4-dienamide] or DNMT inhibitor 5'-Aza-deoxycytidine (Aza) significantly restored E-cadherin levels in NSCLC cells harboring epigenetically silenced E-cadherin expression. These combination treatments also strongly decreased the invasion/migration of these cells, which further emphasized the biologic significance of E-cadherin restoration. Treatment of NSCLC cells, with basal E-cadherin levels, by silibinin further increased the E-cadherin expression and inhibited their migratory and invasive potential. Additional studies showed that silibinin alone as well as in combination with TSA or Aza downmodulate the expression of Zeb1, which is a major transcriptional repressor of E-cadherin. Overall these findings demonstrate the potential of combinatorial treatments of silibinin with HDAC or DNMT inhibitor to modulate EMT events in NSCLC cell lines, leading to a significant inhibition in their migratory and invasive potentials. These results are highly significant, since loss of E-cadherin and metastatic spread of the disease via EMT is associated with poor prognosis and high mortalities in NSCLC.

Silibinin attenuates sulfur mustard analog-induced skin injury by targeting multiple pathways connecting oxidative stress and inflammation

Chemical warfare agent sulfur mustard (HD) inflicts delayed blistering and incapacitating skin injuries. To identify effective countermeasures against HD-induced skin injuries, efficacy studies were carried out employing HD analog 2-chloroethyl ethyl sulfide (CEES)-induced injury biomarkers in skin cells and SKH-1 hairless mouse skin. The data demonstrate strong therapeutic efficacy of silibinin, a natural flavanone, in attenuating CEES-induced skin injury and oxidative stress. In skin cells, silibinin (10 µM) treatment 30 min after 0.35/0.5 mM CEES exposure caused a significant (p<0.05) reversal in CEES-induced decrease in cell viability, apoptotic and necrotic cell death, DNA damage, and an increase in oxidative stress. Silibinin (1 mg) applied topically to mouse skin 30 min post-CEES exposure (2 mg), was effective in reversing CEES-induced increases in skin bi-fold (62%) and epidermal thickness (85%), apoptotic cell death (70%), myeloperoxidase activity (complete reversal), induction of iNOS, COX-2, and MMP-9 protein levels (>90%), and activation of transcription factors NF-κB and AP-1 (complete reversal). Similarly, silibinin treatment was also effective in attenuating CEES-induced oxidative stress measured by 4-hydroxynonenal and 5,5-dimethyl-2-(8-octanoic acid)-1-pyrolline N-oxide protein adduct formation, and 8-oxo-2-deoxyguanosine levels. Since our previous studies implicated oxidative stress, in part, in CEES-induced toxic responses, the reversal of CEES-induced oxidative stress and other toxic effects by silibinin in this study indicate its pleiotropic therapeutic efficacy. Together, these findings support further optimization of silibinin in HD skin toxicity model to develop a novel effective therapy for skin injuries by vesicants.

Epigenetic modifications and p21-cyclin B1 nexus in anticancer effect of histone deacetylase inhibitors in combination with silibinin on non-small cell lung cancer cells

There is a renewed focus on targeted therapy against epigenetic events that are altered during the pathogenesis of lung cancer. However, the use of epigenomic modifiers as monotherapy lacks efficacy; thus, there is a need to develop safe and effective drug combinatorial regimens, which reverse epigenetic modifications and exhibit profound anticancer activity. Based on these perspectives, we evaluated, for the first time, the efficacy and associated mechanisms of a novel combinatorial regimen of histone deacetylase inhibitors (HDACi)-trichostatin A (TSA) and suberoylanilide hydroxamic acid (SAHA)-with silibinin (a flavonolignan with established pre-clinical anti-lung cancer efficacy) against non-small cell lung cancer (NSCLC). Silibinin inhibited HDAC activity and decreased HDAC1-3 levels in NSCLC cells, leading to an overall increase in global histone acetylation states of histones H3 and H4. Combinations of HDCAi with silibinin synergistically augmented the cytotoxic effects of these single agents, which was associated with a dramatic increase in p21 (Cdkn1a). Subsequent ChIP assay indicated increased acetylated histone H3 and H4 levels on p21 promoter region, resulting in its increased transcription. The enhanced p21 levels promoted proteasomal degradation of cyclin B1, the limited supply of which halts the progression of cells into mitosis. Indeed, the resultant biological effect was a significant G 2/M arrest by the combination treatment, followed by apoptotic cell death. Similar epigenetic modulations were observed in vivo, together with a marked reduction in xenograft growth. These findings are both novel and highly significant in establishing that HDACi with silibinin would be safe and effective to suppress NSCLC growth.