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: PTEN-induced growth arrest can be rescued by the co-expression of active PI-3K and downstream effectors such as Akt or PDK1, and also certain small GTPases such as Rac1 and Cdc42, but not by active Ha-ras, raf or RhoA.
Abstract: The tumour suppressor PTEN, also named MMAC1 or TEP1, is associated with a number of malignancies in human populations. This protein has a dual protein phosphatase activity, being also capable to dephosphorylate phosphatidylinositol 3,4,5 triphosphate. We have studied the mechanism of growth suppression attributable to PTEN. We observed that PTEN overexpression inhibits cell growth in a variety of normal and transformed, human and murine cells. Bromodeoxyuridine (BrdU) incorporation and TUNEL labelling experiments in transiently transfected cells demonstrate that this inhibition is due to a cell cycle arrest rather than induction of apoptosis. Given that PTEN is unable to cause cell growth arrest in retinoblastoma (Rb)-deficient cell lines, we have explored the possible requirement for pRb in the PTEN-induced inhibition of cell proliferation. We found that the co-expression of SV40 antigen, but not a mutant form (which binds exclusively to p53), and cyclin D1/cdk4 are able to overcome the PTEN-mediated growth suppression. In addition, the reintroduction of a functional pRb, but not its relatives p107 or p130, in Rb-deficient cells restores the sensitivity to PTEN-induced arrest. Finally, the hyperphosphorylation of transfected pRb is inhibited by PTEN co-expression and restored by PI-3K co-expression. Accordingly, PTEN gene is mostly expressed, in parallel to Akt, in mid-late G1 phase during cell cycle progression prior to pRb hyperphosphorylation. Finally, we have studied the signal transduction pathways modulated by PTEN expression. We found that PTEN-induced growth arrest can be rescued by the co-expression of active PI-3K and downstream effectors such as Akt or PDK1, and also certain small GTPases such as Rac1 and Cdc42, but not by active Ha-ras, raf or RhoA. Collectively, our data link the tumour suppressor activities of PTEN to the machinery controlling cell cycle through the modulation of signalling molecules whose final target is the functional inactivation of the retinoblastoma gene product.
120 citations
Journal Article•
TL;DR: Results suggest that inhibition of advanced human prostate tumor xenograft growth in athymic nude mice by silibinin is associated with its in vivo antiproliferative, proapoptotic, and antiangiogenic efficacy in prostate tumor.
Abstract: Recently, we observed that dietary feeding of silibinin strongly prevents and inhibits the growth of advanced human prostate tumor xenografts in athymic nude mice without any apparent signs of toxicity together with increased secretion of insulin-like growth factor-binding protein 3 from the tumor in to mouse plasma (R. P. Singh et al., Cancer Res., 62:3063-3069, 2002). In the present study, we investigated the effect of silibinin feeding [0.05% and 0.1% (w/w) in diet for 60 days] on the prognostic biomarkers (namely, proliferation, apoptosis, and angiogenesis) in the prostate tumor xenografts of the above-reported study. Immunohistochemical analysis of the tumors for proliferating cell nuclear antigen and Ki-67 showed that silibinin decreases proliferation index by 28-60% and 30-60% (P<0.001) as compared with their controls, respectively. In situ detection of apoptosis by terminal deoxynucleotidyl transferase dUTP-mediated nick end labeling staining of tumors showed a 7.4-8.1-fold (P<0.001) increase in apoptotic cells in silibinin-fed groups over that of control group. Silibinin also increased activated caspase 3-positive cells by 2.3-3.6-fold (P<0.001). CD31 staining for tumor vasculature showed a significant decrease (21-38%; P<0.001) in tumor microvessel density in silibinin-fed groups of tumors as compared with control group of tumors. Tumor sections were also analyzed for vascular endothelial growth factor and insulin-like growth factor-binding protein 3 protein expression, and a slightly decreased and a moderately increased cytoplasmic immunostaining in silibinin-fed groups were observed as compared with the control group, respectively. Together, these results suggest that inhibition of advanced human prostate tumor xenograft growth in athymic nude mice by silibinin is associated with its in vivo antiproliferative, proapoptotic, and antiangiogenic efficacy in prostate tumor.
117 citations
TL;DR: SM/SB has a strong anti-angiogenesis effect on the colon cancer cell line, and this might provide an alternative treatment option for anti-cancer treatment.
94 citations
"Effects and mechanisms of silibinin..." refers background or result in this paper
...Possible effects of silibinin on angiogenesis In previous studies, silibinin has been reported to inhibit angiogenesis in non-HCC cancer cell lines [ 13 ]...
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.... Previous studies on other cancer cell lines showed a significant inhibitory effect of silibinin on the cell cycle progression [ 11-13 ]...
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.... Studies indicated that silibinin induces apoptosis in several malignant cell lines [ 13 ,14,18]...
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..., colon [ 13 ,14] ,...
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.... As noted in previous studies on other cancer cell lines [ 12-14 ]...
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TL;DR: The antiproliferative and apoptotic efficacy in rat PCA cell lines of silibinin, a major active flavonoids component of silymarin, which consists of a group of flavonoid antioxidants occurring in milk thistle (Silybum marianum), is assessed.
Abstract: BACKGROUND
The tremendous impact of prostate cancer (PCA) on the US male population has led to an increased attention on its prevention and on therapeutic intervention. Short-term models are needed to quickly screen the efficacy of promising agents against PCA. We have established recently several rat PCA cell lines from primary PCA in rats induced by a MNU-testosterone protocol, but their usefulness as a model for screening PCA preventive and therapeutic agents remains to be established. With the rationale that agents found effective in these cells could be promising for efficacy testing in long-term in vivo experiments, e.g., with MNU-testosterone–induced PCA in rats, the major goal of our study was to assess the antiproliferative and apoptotic efficacy in rat PCA cell lines of silibinin, a major active flavonoid component of silymarin, which consists of a group of flavonoid antioxidants occurring in milk thistle (Silybum marianum).
METHODS
Three rat PCA cell lines, namely H-7, I-8, and I-26, were treated with silibinin or silymarin, a crude silibinin-containing preparation, at various doses for varying lengths of time. Cell growth and viability studies were carried out by using hemocytometer and Trypan blue dye exclusion methods. Cell cycle distribution studies were conducted by using PI staining and flow cytometry analysis, and DNA synthesis was assessed by bromodeoxyuridine incorporation. Apoptotic cell death was assessed as DNA damage by using an enzyme-linked immunosorbent assay method and by annexin V and PI staining followed by flow cytometry analysis.
RESULTS
Silibinin resulted in a significant growth inhibition and reduction in cell viability in each cell line studied in both a dose- and a time-dependent manner. Silibinin treatment of H-7 and I-8 cells at 100 μM dose for 12 and 24 hr resulted in a G1 arrest but caused S phase arrest after a 48-hr treatment period in each cell line studied. Similar silibinin treatment of I-26 cells resulted in a slight S phase arrest at all time points studied. Consistent with these findings, silibinin showed a strong inhibition of DNA synthesis. Silibinin also induced a substantial apoptotic death in each cell line studied. Similar to silibinin, silymarin induced growth inhibition and reduced viability in a dose- and time-dependent manner.
CONCLUSION
This study demonstrates that silibinin as well as silymarin induce growth inhibition and apoptosis in rat PCA cells. These results form a strong rationale for PCA prevention and therapeutic intervention studies with silibinin and silymarin in animal models, such as the MNU-testosterone rat PCA model, to establish their efficacy and to further define their mechanisms of action under in vivo conditions. Prostate 53: 211–217, 2002. © 2002 Wiley-Liss, Inc.
82 citations
"Effects and mechanisms of silibinin..." refers background or result in this paper
.... As noted in previous studies on other cancer cell lines [ 12-14 ]...
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.... Previous studies on other cancer cell lines showed a significant inhibitory effect of silibinin on the cell cycle progression [ 11-13 ]...
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...Studies demonstrated silibinin's inhibitory effects on multiple cancer cell lines, including prostate [ 9-12 ]...
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TL;DR: The present study showed that celecoxib causes COX-2-dependent and COX2-independent growth inhibition of hepatocellular carcinoma cells and xenografts by decreased retinoblastoma phosphorylation and DP1/E2F1 complex; increased activation of caspase-3 and caspasing-9; and increased expression of proliferator-activated receptor γ.
Abstract: Purpose: Cyclooxygenase-2 (COX-2) inhibitors cause growth inhibition of human hepatocellular carcinoma cells but it remains unclear whether this is both COX-2 dependent and independent. The related mechanisms remain to be determined. The present study was aimed to determine the effect of celecoxib on growth of hepatocellular carcinoma cells and xenografts and the related mechanisms. Experimental Design: Both low COX-2 expressing PLC/PRF/5 and high COX-2 expressing HuH7 cells, and nude mice bearing hepatocellular carcinoma xenografts were used to study the effect and mechanisms of celecoxib on hepatocellular carcinoma cell growth. Results: Celecoxib resulted in a comparable growth inhibition of both hepatocellular carcinoma cells that was associated with decreased production of prostaglandin E 2 and increased peroxisome proliferator-activated receptor γ in both cells. Addition of prostaglandin E 2 only partially counteracted the effect of celecoxib on both cells. Celecoxib resulted in a significant reduction of retinoblastoma phosphorylation and DP1/E2F1 complex in both cells. Celecoxib caused a significant increase of apoptosis and activation of caspase-3 and caspase-9 in both cells. In nude mice inoculated with HuH7 cells, celecoxib resulted in decreased frequency and mean weight of hepatocellular carcinoma xenografts. Conclusion: The present study showed that celecoxib causes COX-2-dependent and COX-2-independent growth inhibition of hepatocellular carcinoma cells and xenografts by ( a ) decreased retinoblastoma phosphorylation and DP1/E2F1 complex; ( b ) increased activation of caspase-3 and caspase-9; and ( c ) increased expression of proliferator-activated receptor γ. The present study significantly extended our knowledge on the effect and mechanisms of celecoxib-induced inhibition of hepatocellular carcinoma cell growth.
79 citations
"Effects and mechanisms of silibinin..." refers methods or result in this paper
...Using MTT assay [37, 38 ] , we demonstrated that silibinin treatment resulted in a potent inhibition of four different human HCC cell lines, indicating its broad spectrum of anti-HCC effects....
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.... Briefly, the effects of silibinin on HCC cell growth were then determined after 24 h of incubation by optical density absorbance at 490 nm according to the manufacturer's instruction [37, 38 ]...
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...All the cells were cultured, as previously reported [37, 38 ]...
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...Apoptosis was determined in duplicate using an EIA kit for cell death detection, as previously reported [37, 38 ]...
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...Human HCC cell lines, HuH7, HepG2, PLC/PRF/5, and Hep3B cells [37, 38 ]...
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