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Journal ArticleDOI

Effects and mechanisms of silibinin on human hepatoma cell lines.

28 Oct 2007-World Journal of Gastroenterology (Baishideng Publishing Group Inc)-Vol. 13, Iss: 40, pp 5299-5305
TL;DR: It is demonstrated that silibinin significantly reduced the growth of HuH7, HepG2, Hep3B, and PLC/PRF/5 human hepatoma cells and increased acetylation of histone H3 and H4, indicating a possible role of altered histone acetylations in silib inin-reduced HCC cell proliferation.
Abstract: AIM: To investigate in vitro effects and mechanisms of silibinin on hepatocellular carcinoma (HCC) cell growth. METHODS: Human HCC cell lines were treated with different doses of silibinin. The effects of silibinin on HCC cell growth and proliferation, apoptosis, cell cycle progression, histone acetylation, and other related signal transductions were systematically examined. RESULTS: We demonstrated that silibinin significantly reduced the growth of HuH7, HepG2, Hep3B, and PLC/PRF/5 human hepatoma cells. Silibinin-reduced HuH7 cell growth was associated with significantly up-regulated p21/CDK4 and p27/CDK4 complexes, down-regulated Rb-phosphorylation and E2F1/DP1 complex. Silibinin promoted apoptosis of HuH7 cells that was associated with down-regulated survivin and up-regulated activated caspase-3 and -9. Silibinin's anti-angiogenic effects were indicated by down-regulated metalloproteinase-2 (MMP2) and CD34. We found that silibinin-reduced growth of HuH7 cells was associated with increased activity of phosphatase and tensin homolog deleted on chromosome ten (PTEN) and decreased p-Akt production, indicating the role of PTEN/PI3K/Akt pathway in silibinin-mediated anti-HCC effects. We also demonstrated that silibinin increased acetylation of histone H3 and H4 (AC-H3 and AC-H4), indicating a possible role of altered histone acetylation in silibinin-reduced HCC cell proliferation. CONCLUSION: Our results defined silibinin's in vitro anti-HCC effects and possible mechanisms, and provided a rationale to further test silibinin for HCC chemoprevention.

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Citations
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Journal ArticleDOI
TL;DR: It is emphasized how increased understanding of the chemopreventive effects of dietary polyphenols on specific epigenetic alterations may provide unique and yet unexplored novel and highly effective chemopresventive strategies for reducing the health burden of cancer and other diseases in humans.

429 citations

Journal ArticleDOI
TL;DR: The protective effects of silymarin and its major active constituent, silibinin, studied in various tissues, suggest a clinical application in cancer patients as an adjunct to established therapies, to prevent or reduce chemotherapy as well as radiotherapy-induced toxicity.

369 citations


Cites background from "Effects and mechanisms of silibinin..."

  • ...[31]....

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  • ...Silibinin also promotes apoptosis of human hepatoma HuH7 cells by down-regulating survivin and up-regulating activated caspase-3 and -9 [31]....

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  • ...In other studies, silibinin significantly upregulated p21/CDK4 and p27/CDK4 complexes and down-regulated Rb-phosphorylation and E2F1/DP1 complex thereby inhibiting human hepatoma HuH7 cell growth [31]....

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Journal ArticleDOI
TL;DR: A review of available studies on the effects of the purified product silybin on liver cells or on experimentally induced liver damage, and in patients with liver disease indicates that the bioavailability of slybin phytosome is higher than that of silymarin and is less influenced by liver damage.
Abstract: Herbal products are increasingly used, mainly in chronic liver disease. Extracts of milk thistle, Silymarin and silybin, are the most prescribed natural compounds, with different indications, but with no definitive results in terms of clinical efficacy. This review analyzes the available studies on the effects of the purified product silybin, both as a free and a conjugated molecule, on liver cells or on experimentally induced liver damage, and in patients with liver disease. We searched PUBMED for articles pertaining to the in vitro and in vivo effects of silybin, its antifibrotic, anti-inflammatory, and antioxidant properties, as well as its metabolic effects, combined with the authors' own knowledge of the literature. Results indicate that the bioavailability of silybin phytosome is higher than that of silymarin and is less influenced by liver damage; silybin does not show significant interactions with other drugs and at doses < 10 g/d has no significant side effects. Experimental studies have clearly demonstrated the antifibrotic, antioxidant and metabolic effects of silybin; previous human studies were insufficient for confirming the clinical efficacy in chronic liver disease, while ongoing clinical trials are promising. On the basis of literature data, silybin seems a promising drug for chronic liver disease.

295 citations

Journal ArticleDOI
TL;DR: The aim of this review is to examine scientific studies concerning the effects derived from silymarin/silybin use in chronic liver diseases, cirrhosis and hepatocellular carcinoma.
Abstract: Silymarin is the extract of Silybum marianum, or milk thistle, and its major active compound is silybin, which has a remarkable biological effect. It is used in different liver disorders, particularly chronic liver diseases, cirrhosis and hepatocellular carcinoma, because of its antioxidant, anti-inflammatory and antifibrotic power. Indeed, the anti-oxidant and anti-inflammatory effect of silymarin is oriented towards the reduction of virus-related liver damages through inflammatory cascade softening and immune system modulation. It also has a direct antiviral effect associated with its intravenous administration in hepatitis C virus infection. With respect to alcohol abuse, silymarin is able to increase cellular vitality and to reduce both lipid peroxidation and cellular necrosis. Furthermore, silymarin/silybin use has important biological effects in non-alcoholic fatty liver disease. These substances antagonize the progression of non-alcoholic fatty liver disease, by intervening in various therapeutic targets: oxidative stress, insulin resistance, liver fat accumulation and mitochondrial dysfunction. Silymarin is also used in liver cirrhosis and hepatocellular carcinoma that represent common end stages of different hepatopathies by modulating different molecular patterns. Therefore, the aim of this review is to examine scientific studies concerning the effects derived from silymarin/silybin use in chronic liver diseases, cirrhosis and hepatocellular carcinoma.

270 citations


Cites background from "Effects and mechanisms of silibinin..."

  • ...proved that silybin significantly reduces HuH7, HepG2, Hep3B, and PLC/PRF/5 human hepatoma cells growth by increasing cyclin-dependent kinase inhibitor p21 and p27/cyclin-dependent kinase (CDK) 4 complexes, by reducing retinoblastoma protein (Rb)-phosphorylation and transcription factor E2F1/transcription factor dimerization Partner (DP) 1 complex, as well as by promoting induction of codifying genes for caspase 3–9 and reducing the levels of survivin, whose sovraexpression is associated with a reduction of cell death [140,141]....

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Journal ArticleDOI
TL;DR: Detailed mechanistic analyses revealed that silibinin targets signaling molecules involved in the regulation of epithelial-to-mesenchymal transition, proteases activation, adhesion, motility, invasiveness as well as the supportive tumor-microenvironment components, thereby inhibiting metastasis.
Abstract: Cancer is a major health problem around the world. Research efforts in the last few decades have been successful in providing better and effective treatments against both early stage and localized cancer, but clinical options against advanced metastatic stage/s of cancer remain limited. The high morbidity and mortality in most of the cancers are attributed to their metastatic spread to distant organs. Due to its extreme clinical relevance, metastasis has been extensively studied and is now understood as a highly complex biological event that involves multiple steps including acquisition of invasiveness by cancer cells, intravasation into circulatory system, survival in the circulation, arrest in microvasculature, extravasation, and growth at distant organs. The increasing understanding of molecular underpinnings of these events has provided excellent opportunity to target metastasis especially through nontoxic and biologically effective nutraceuticals. Silibinin, a popular dietary supplement isolated from milk thistle seed extracts, is one such natural agent that has shown biological efficacy through pleiotropic mechanisms against a variety of cancers and is currently in clinical trials. Recent preclinical studies have also shown strong efficacy of silibinin to target cancer cell’s migratory and invasive characteristics as well as their ability to metastasize to distant organs. Detailed mechanistic analyses revealed that silibinin targets signaling molecules involved in the regulation of epithelial-to-mesenchymal transition, proteases activation, adhesion, motility, invasiveness as well as the supportive tumor-microenvironment components, thereby inhibiting metastasis. Overall, the long history of human use, remarkable nontoxicity, and preclinical efficacy strongly favor the clinical use of silibinin against advanced metastatic cancers.

213 citations

References
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Journal ArticleDOI
TL;DR: The results of the study suggest that the increased levels of Trx-1 in human tumors could lead to functional inhibition of PTEN tumor suppressor activity providing an additional mechanism for tumorigenesis with loss ofPTEN activity.

185 citations


"Effects and mechanisms of silibinin..." refers methods in this paper

  • ...The release of phosphate from the substrate was measured in a colorimetric assay using the Biomol Green Reagent (Plymouth Meeting, PA) [ 39 ]...

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Journal ArticleDOI
TL;DR: It is observed that silibinin exerted a dose‐ and time‐dependent inhibitory effect on the invasion and motility, but hardly on the adhesion, of highly metastatic A549 cells in the absence of cytotoxicity.
Abstract: Cancer metastasis, involving multiple processes and various cytophysiological changes, is a primary cause of cancer death and may complicate the clinical management, even lead to death Silibinin is a flavonoid antioxidant and wildly used for its antihepatotoxic properties and recent studies have revealed pleiotropic anticancer and antiproliferative capabilities of silibinin In this study, we first observed that silibinin exerted a dose- and time-dependent inhibitory effect on the invasion and motility, but hardly on the adhesion, of highly metastatic A549 cells in the absence of cytotoxicity To look at the precise involvement of silibinin in cancer metastasis, A549 cells were treated with silibinin at various concentrations, up to 100 microM, for a defined period and then subjected to gelatin zymography, casein zymography and Western blot to investigate the impacts of silibinin on metalloproteinase-2 (MMP-2), urokinase plasminogen activator (u-PA), and tissue inhibitor of metalloproteinase-2 (TIMP-2), respectively The results showed that a silibinin treatment may decrease the expressions of MMP-2 and u-PA in a concentration- and time-dependent manner and enhance the expression of TIMP-2 Further analysis with semi-quantitative RT-PCR showed that silibinin may regulate the expressions of MMP-2 and u-PA on the transcriptional level while on the translational or post-translational level for TIMP-2

161 citations

Journal ArticleDOI
TL;DR: Silymarin retards the development of alcohol-induced hepatic fibrosis in baboons, consistent with several positive clinical trials, and the negative outcome observed in other trials possibly reflects poor compliance resulting in irregular or low sily marin intake.
Abstract: UNLABELLED GOAL/BACKGROUND: Hepatoprotective effects of silymarin in patients with alcoholic liver disease are controversial. For strict control, this was assessed in non-human primates. STUDY Twelve baboons were fed alcohol with or without silymarin for 3 years with a nutritionally adequate diet. RESULTS Silymarin opposed the alcohol-induced oxidative stress (assessed by plasma 4-hydroxynonenal) and the rise in liver lipids and circulating ALT. Alcohol also increased hepatic collagen type I by 50% over the 3 years with a significant rise in mRNA for alpha1 (I) procollagen, both prevented by silymarin. There were corresponding morphologic changes: at 36 months, 2 of 6 animals fed alcohol had cirrhosis and 2 septal fibrosis, with perivenular fibrosis in 2, whereas with alcohol + silymarin, there was only 1 cirrhosis and 1 septal fibrosis, with perivenular fibrosis in 2, and virtually no lesions in the remaining 2. CONCLUSIONS Silymarin retards the development of alcohol-induced hepatic fibrosis in baboons, consistent with several positive clinical trials. The negative outcome observed in other trials possibly reflects poor compliance resulting in irregular or low silymarin intake. Thus, in view of the innocuity of silymarin, it might be advisable in future clinical studies to insure the controlled administration of sufficient amounts of silymarin.

150 citations


"Effects and mechanisms of silibinin..." refers background in this paper

  • .... It is well known that milk thistle is safe and well-tolerated, and it protects the liver from drug or alcohol-related injury [7, 8 ]...

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  • ...It is well known that milk thistle is safe and well tolerated, and it protects the liver from drug or alcohol-related injury [7, 8 ]...

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Journal ArticleDOI
TL;DR: A strong preventive efficacy of silibinin against photocarcinogenesis, which involves the inhibition of DNA synthesis, cell proliferation, and cell cycle progression and an induction of apoptosis is shown.
Abstract: Here, we assessed the protective effect of silibinin on UVB-induced skin carcinogenesis in SKH-1 hairless mice. Topical application of silibinin before or immediately after UVB exposure or its dietary feeding resulted in a strong protection against photocarcinogenesis, in terms of tumor multiplicity (60-66%; P < 0.001), tumor volume per mouse (93-97%; P < 0.001) and tumor volume per tumor (80-91%; P < 0.001). Silibinin also moderately inhibited tumor incidence (5-15%; P < 0.01) and delayed tumor latency period (up to 4 weeks; P < 0.01-0.001). To investigate in vivo molecular mechanisms of silibinin efficacy, tumors and uninvolved skin from tumor-bearing mice were examined immunohistochemically for proliferation, p53, apoptosis, and activated caspase-3. Silibinin treatment showed a strong decrease (P < 0.001) in proliferating cell nuclear antigen-positive cells and an increase in p53-positive (P < 0.005-0.001), terminal deoxynucleotidyltransferase-mediated nick end labeling-positive (P < 0.005-0.001), and cleaved caspase-3-positive cells (P < 0.001). Western blot analysis of normal skin and tumor lysates showed that silibinin decreases the levels of cyclin-dependent kinase 2 and cyclin-dependent kinase 4 and associated cyclins A, E, and D1, together with an up-regulation of Cip1/p21, Kip1/p27, and p53. Silibinin also showed a strong phosphorylation of extracellular signal-regulated protein kinase 1/2, stress-activated protein kinase/c-JUN NH2-terminal kinase 1/2, and p38 mitogen-activated protein kinases but inhibited Akt phosphorylation and decreased survivin levels with an increase in cleaved caspase-3. Together, these results show a strong preventive efficacy of silibinin against photocarcinogenesis, which involves the inhibition of DNA synthesis, cell proliferation, and cell cycle progression and an induction of apoptosis. Furthermore, these results also identify in vivo molecular mechanisms of silibinin efficacy against photocarcinogenesis.

150 citations


"Effects and mechanisms of silibinin..." refers background in this paper

  • .... It was reported that silibinin affects Akt expression in prostate cancer cells [ 16 ]...

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  • ...skin [ 15-17 ] , bladder...

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  • ...Effects of silibinin on PTEN/PI3K/Akt pathway It has been reported that the PTEN/PI3K/Akt pathway is involved in cancer growth [ 16 ,46]...

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Journal ArticleDOI
TL;DR: While some of the functions of PTEN have been elucidated, it is clear that there is much more to discover about the roles of this unique protein.
Abstract: The level of phosphorylation within cells is tightly regulated by the concerted action of protein kinases and protein phosphatases [Hunter, T. (1995) Cell 80, 225-236]. Disregulation in the activity of either of these players can lead to cellular transformation. Many protein tyrosine kinases are proto-oncogenes and it has been postulated that some protein phosphatases may act as tumor suppressors. Herein we will review the recent findings addressing the roles the candidate tumor suppressor PTEN/MMAC1/TEP1 (PTEN, phosphatase and tensin homologue deleted from chromosome 10; MMAC 1, mutated in multiple advanced cancers 1; TEP1, TGF beta regulated and epithelial cell enriched phosphatase 1) plays in signal transduction and tumorigenesis. PTEN is a dual specificity protein phosphatase (towards phospho-Ser/Thr and phospho-Tyr) and, unexpectedly, also has a phosphoinositide 3-phosphatase activity. PTEN plays an important role in the modulation of the 1-phosphatidylinositol 3-kinase (PtdIns 3-kinase) pathway, by catalyzing the degradation of the PtdIns(3,4,5)P3 generated by PtdIns 3-kinase; this inhibits the downstream functions mediated by the PtdIns 3-kinase pathway, such as activation of protein kinase B (PKB, also known as Akt), cell survival and cell proliferation. Furthermore, PTEN modulates cell migration and invasion by negatively regulating the signals generated at the focal adhesions, through the direct dephosphorylation and inhibition of focal adhesion kinase (FAK). Growth factor receptor signaling is also negatively regulated by PTEN, through the inhibition of the adaptor protein Shc. While some of the functions of PTEN have been elucidated, it is clear that there is much more to discover about the roles of this unique protein.

148 citations


"Effects and mechanisms of silibinin..." refers background in this paper

  • .... PTEN is a tumor suppressor gene and the deletion or inactivation of this gene has been described in a variety of cancer cell lines [30,33, 53 ]...

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