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.
Citations
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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
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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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
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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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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TL;DR: The differential expression of survivin in cancer versus normal tissues makes it a useful tool in cancer diagnosis and a promising therapeutic target.
346 citations
"Effects and mechanisms of silibinin..." refers background in this paper
.... We demonstrated that silibinin causes a significant increase in apoptosis of HuH7 cells which was associated with decreased survivin expression and increased activated caspase-3 and -9. Because survivin can bind with caspases [19,50, 51 ]...
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TL;DR: There is preliminary evidence that changes in serum AFP may be a more accurate and sensitive way of determining the degree of response to treatment than conventional imaging procedures that rely on physical determination of tumor size.
344 citations
"Effects and mechanisms of silibinin..." refers methods in this paper
...Plasma alphafetoprotein (AFP) has been used as a clinical marker for diagnosing and monitoring recurrent HCC [ 23-25 ]...
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TL;DR: It is concluded that AFP elevation, more than a coincidental epiphenomenon, appears to contribute to vascular invasion and HCC progression and help to identify subsets of HCC patients with increased risk for early recurrence and poor prognosis after hepatectomy.
Abstract: alpha-Fetoprotein (AFP) is often elevated in hepatocellular carcinoma (HCC). This study was to elucidate the significance and related factors of AFP elevation in HCC in 781 unifocal HCCs receiving curative hepatectomy. We showed that high AFP (> 200 ng/ml), which was associated with AFP mRNA expression in HCC (p = 0.00001), correlated with major clinicopathologic factors. Younger age (< or = 55 years; p=0.00001), hepatitis B surface antigen (HBsAg) in serum (p=0.00001), p53 mutation (p=0.008), large tumor (p=0.00001), vascular invasion (p=0.00001) and early tumor recurrence (p=0.00001) were significant associates of high AFP, while anti-HCV in serum and beta-catenin mutation in HCC had less frequent high AFP (p=0.013 and < 0.0001, respectively). We also showed that HCC with high AFP had a lower 10-year survival (p < 0.0001), particularly in large HCC (p < 0.0001). At univariate analysis, high AFP (p < 0.0001), HBsAg positivity (p=0.05), p53 mutation (p=0.0004), liver cirrhosis (p=0.0094), large tumor (p=0.0003), vascular invasion (p < 0.0001) and early recurrence (p < 0.0001) were significant unfavorable prognostic factors. In Cox proportional hazards regression analysis, high AFP remained a borderline significance (OR=1.2; CI=1.0-1.4) after adjustment for the effect of tumor size and tumor stage (p=0.0821). Furthermore, the detection of AFP mRNA in the liver of AFP mRNA-positive HCC was associated with more frequent early recurrence (p=0.0026) and might be a useful marker of intrahepatic spread. We therefore conclude that AFP elevation, more than a coincidental epiphenomenon, appears to contribute to vascular invasion and HCC progression and help to identify subsets of HCC patients with increased risk for early recurrence and poor prognosis after hepatectomy.
272 citations
TL;DR: Inactivation of the tumor suppressor gene PTEN/MMAC1/TEP1, located on chromosome 10q23, is a common event in advanced stages of diverse human malignancies, but the prognostic role of PTEN expression in patients with hepatocellular carcinoma (HCC) has not been characterized.
Abstract: BACKGROUND
Inactivation of the tumor suppressor gene PTEN/MMAC1/TEP1, located on chromosome 10q23, is a common event in advanced stages of diverse human malignancies. However, the prognostic role of PTEN expression in patients with hepatocellular carcinoma (HCC) has not been characterized.
METHODS
One hundred five resected specimens were collected from patients with HCC. Expression levels of PTEN and p53 in clinical samples were analyzed by immunohistochemistry.
RESULTS
Immunohistochemical analysis of 105 HCC tissue specimens revealed that decreased or absence of PTEN immunostaining was found in 43 specimens (40.9%). Reduced PTEN expression levels were correlated with increased tumor grade (P = 0.017), advanced disease stage (P = 0.016), and elevated serum α-fetoprotein (αFP) levels (P = 0.001). Kaplan–Meier analysis indicated that patients with reduced PTEN levels had shorter overall survival (P = 0.001) and higher recurrence rates (P = 0.0007) compared with patients who had intact PTEN expression. Examining p53 expression unveiled an inverse correlation between p53 overexpression and reduced PTEN expression in patients with HCC (P = 0.004). In addition, patients with p53 overexpression had shorter overall survival compared with patients who were without p53 overexpression (P = 0.0014). Univariate and multivariate analyses revealed that reduced PTEN expression was an independent prognostic factor for survival in patients with HCC.
CONCLUSIONS
The current study demonstrated that reduced PTEN expression levels are involved in the pathogenesis of HCC. Moreover, decreased PTEN expression was correlated with tumor progression, high αFP levels, p53 overexpression, and poor prognosis in patients with HCC. Cancer 2003;97:1929–40. © 2003 American Cancer Society.
DOI 10.1002/cncr.11266
263 citations
"Effects and mechanisms of silibinin..." refers background in this paper
...There is growing evidence of PTEN/PI3K/Akt pathway in hepatocarcinogenesis [27,32, 47-49 ]...
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...It was reported that altered PTEN expression or activity is associated with the pathogenesis of HCC [ 47-49 ]...
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TL;DR: Clinicians and preclinical investigators alike are urged to exercise rigor in nomenclature and use pure compounds or precisely defined chemical mixtures in subsequent studies of milk thistle extracts.
Abstract: Extracts of milk thistle have been recognized for centuries as "liver tonics" and are well-known to prevent or reverse hepatotoxicity of reactive drug metabolites or naturally occurring toxins. Milk thistle extracts are now under intense study in the experimental therapeutics of cancer for chemoprevention, treatment, and amelioration of chemotherapy side effects. Precision in nomenclature, however, has lagged behind this progress. The crude commercial product of milk thistle is termed silymarin, a complex of at least 7 flavonolignans and 1 flavonoid that comprises 65% to 80% of milk thistle extract. From silymarin is derived silibinin, a semipurified fraction once thought to be a single compound but now recognized as a 1:1 mixture of 2 diastereoisomers, silybin A and silybin B. The distinction between silymarin and silibinin is not only important to understanding the historical literature, but thorough characterization and use of chemically defined mixtures in preclinical and clinical studies are essential to the progress of these botanical compounds as human therapeutics. As a result, we urge clinicians and preclinical investigators alike to exercise rigor in nomenclature and use pure compounds or precisely defined chemical mixtures in subsequent studies. Herein, we provide a guide to the proper nomenclature and composition of milk thistle extracts and discuss the known pharmacokinetic studies of these botanical medicines. The drug-interaction potential of these extracts appears to be quite low, and in fact, silibinin appears to synergize with the antitumor effects of some commonly used chemotherapeutics. However, some precautions are advised as high-dose, phase II studies are conducted.
251 citations
"Effects and mechanisms of silibinin..." refers background in this paper
...Silibinin is a polyphenolic flavonoid and the major biologically active compound of milk thistle [ 4-6 ]...
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...Effects of Silibinin on Apoptosis Apoptosis is another important regulatory step in controlling cancer cell proliferation [ 4 ]...
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...It is a popular dietary supplement widely used in the United States and Europe [ 4 ]...
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