Silibinin induces hepatic stellate cell cycle arrest via enhancing p53/p27 and inhibiting Akt downstream signaling protein expression

BACKGROUND： Proliferation of hepatic stellate cells （HSCs） plays a pivotal role in the progression of liver fibrosis conse- quent to chronic liver injury. Silibinin, a flavonoid compound, has been shown to possess anti-fibrogenic effects in animal models of liver fibrosis. This was attributed to an inhibition of cell proliferation of activated HSCs. The present study was to gain insight into the molecular pathways involved in silibinin anti-fibrogenic effect. METHODS： The study was conducted on LX-2 human stellate cells treated with three concentrations of silibinin （10, 50 and 100 μmol/L） for 24 and 96 hours. At the end of the treatment cell viability and proliferation were evaluated. Protein expression of p27, p21, p53, Akt and phosphorylated-Akt was evaluated by Western blotting analysis and Ki-67 protein expression was by immunocytochemistry. Sirtuin activity was evaluated by chemiluminescence based assay. RESULTS： Silibinin inhibits LX-2 cell proliferation in doseand time-dependent manner; we showed that silibinin upregulated the protein expressions of p27 and p53. Such regulation was correlated to an inhibition of both downstream Akt and phosphorylated-Akt protein signaling and Ki-67 protein expression. Sirtuin activity also was correlated to silibinin- inhibited proliferation of LX-2 cells. CONCLUSION： The anti-proliferative effect of silibinin on LX-2 human steUate cells is via the inhibition of the expres- sions of various cell cycle targets including p27, Akt and sir- tuin signaling.

Antiproliferative role of Indig ofera aspalathoides on 20 methylcholanthrene induced fibrosarcoma in rats

Objective:To find out the anticancer effect of indigofera aspalathoides(L.aspalathoides)on20-methylcholanthrene induced fibrosarcoma in rats.Methods:Fibrosarcoma was induced in Wistar strain male albino rats by 2O-methylcholanthrene.Intraperitoneous(i.p.)administration of250 mg/kg body weight/day of aqueous extract of I.aspalathoides for 30 d effectively suppressed chemically induced tumors.Parameters such as body weight,liver and kidney weight,tumor weight,mean survival time,behavioral changes,blood glucose,blood glycogen and marker enzymes such as alanine aminotransferase(ALT),aspartate aminotransferase(AST),alkaline phosphatase(ALP),acid phosphatase(ACP)and 5'-nucleiotidase(5'-NT)in serum,liver and kidney and lipid profiles such as total cholesterel,phospholipids,free fatty acids in liver and kidney of control and experimental animals were studied.Results:Fibrosarcoma bearing animals were ferocious and anxious.The mean survival time was found to increase after the treatment.The body weights were significantly decreased(P<0.001)in groupⅡfibrosarcoma animals which steadily increased after the treatment with I.aspalathoides.The liver and kidney weights were significantly increased whereas the tumor weights decreased as compared to the weights in untreated fibrosarcoma bearing rats.The blood glucose and the liver and kidney glycogen levels were found to decrease significantly(P<0.001)in groupⅡanimals.Elevated activities of marker enzymes were observed in serum,liver and kidney of fibrosarcoma bearing GroupⅡanimals which were normalize after I.aspalathoides treatment.In the liver and kidney of GroupⅡanimals the total cholesterol increased whereas the pbospbolipids and free fatty acid levels decreased(P<0.001)which were normalized after treatment.Conclusions:The treatment by I.aspalathoides on fihrosarcoma bearing rats has improved the levels of various parameters indicating its antiproliferative and anticancer activity.

Effects of Terminalia arjuna bark extract on apoptosis of human hepatoma cell line HepG2

AIM：To investigate the effects of Terminalia arjuna （T. arjuna） extract on human hepatoma cell line （HepG2） and its possible role in induction of apoptosis.METHODS： Human hepatoma cells were treated with different concentrations of ethanolic extract of T. arjuna and its cytotoxicity effect was measured by trypan blue exclusion method and lactate dehydrogenase leakage assay. Apoptosis was analyzed by light and fluorescence microscopic methods, and DNA fragmentation. The mechanism of apoptosis was studied with expression of p53 and caspase-3 proteins. Glutathione （GSH） content was also measured in HepG2 cells after T. arjuna treatment.RESULTS： T. arjuna inhibited the proliferation of HepG2 cells in a concentration-dependent manner. Apoptotic morphology was observed in HepG2 cells treated with T. arjuna at the concentrations of 60 and 100 mg/L. DNA fragmentation, accumulation of p53 and cleavage of procaspase-3 protein were observed in HepG2 cells after the treatment with T. arjuna. The depletion of GSH was observed in HepG2 cells treated with T. arjuna.CONCLUSION： T. arjuna induced cytotoxicity in HepG2 cells in vitro. Apoptosis of HepG2 cells may be due to the DNA damage and expression of apoptotic proteins. Depletion of GSH may be involved in the induction of apoptosis of HepG2 cells.

Exposure to polycyclic aromatic hydrocarbons with special focus on cancer

Polycyclie aromatic hydrocarbons(PAHs) are a group of compounds consisting of two or more fused aromatic rings.Most of them are formed during incomplete combustion of organic materials such as wood and fossil fuels,petroleum products,and coal.The composition of PAH mixtures varies with the source and is also affected by selective weathering effects in the environment.PAHs are ubiquitous pollutants frequently found in a variety of environments such as fresh water and marine sediments,the atmosphere,and ice.Due to their widespread distribution,the environmental pollution due to PAHs has aroused global concern.Many PAHs and their epoxides are highly toxic,mutagenic and/or carcinogenic to microorganisms as well as to higher forms of life including humans.The main aim of this review is to provide contemporary information on PAH sources,route of exposure,worldwide emission rate,and adverse effects on humans,especially with reference to cancer.

Silibinin alleviates N-nitrosodimethylamine-induced glutathione dysregulation and hepatotoxicity in rats

The present study was designed to evaluate the hepatoprotective and antioxidant potentials of silibinin(SBN)against N-nitrosodimethylamine(DMN)-induced toxic insults in the rat liver.The liver damage was induced in Wistar albino rats by repeated administration of DMN(10 mg·kg-1 b.w.,i.p.)on 3 consecutive days per week for 3 weeks.SBN(100 mg·kg-1 b.w.,p.o.)was given daily to the DMN treated rats for two weeks.The marker enzymes of liver toxicity and second-line enzymic and non-enzymic antioxidants were evaluated in serum and liver tissues before and after SBN treatment.Histopathology of the liver was evaluated by H & E staining.The DMN treatment produced a progressive increase in all the serum marker enzymes(AST,ALT,ALP,LDH,and γ-GT),peaking on Day 21.This treatment produced highly significant decreases in all the second-line antioxidant parameters(GSH,GST,GR,GPx,and vitamins C and E).The SBN treatment significantly reversed the DMN-induced damages,towards normalcy.Histopathological studies confirmed the development of liver toxicity in DMN-treated rats,which was reversed by SBN treatment in corroboration with the aforementioned biochemical results,indicating the hepatoprotective and antioxidant properties of SBN.In conclusion,the DMN-induced degenerative changes in the liver were alleviated by SBN treatment and this protective ability may be attributed to its antioxidant,free radical scavenging,and membrane stabilizing properties.

Plant derived antioxidants and antifibrotic drugs:past,present and future

Hepatic fibrosis occurs as a wound-healing process after several forms of chronic hepatic injury.Activation and proliferation of hepatic stellate cells play pivotal role in the pathogenesis of hepatic fibrosis.Many researchers,from the therapeutic perspective,have focused their attention on searching for novel agents with inhibitory effects on hepatic stellate cells proliferation and activation to prevent hepatic fibrogenesis and a number of plant derived antioxidants have been tested as anti-fibrogenic agents,they generally suppress proliferation and collagen synthesis.Plants remain an imperative source of novel drugs,novel drug leads and new chemical entities.The plant based drug discovery resulted primarily in the development of antioxidant,anti-cancer and other anti-infectious agents and continues to contribute to the new leads in clinical trials.This review summarizes some of those most important plant derived anti-fibrotic drugs and their beneficial effects on experimentally induced hepatic fibrosis in vitro and in vivo.The plant derived antioxidant compounds described herein are curcumin,silymarin,silibinin,baicalein,resveratrol,salvianolic acids,tetrandine,quercetin and berberine.Studies from ours and as demonstrated by pervious workers much information has been accumulated over the past two decades through in vivo and in vitro.In light of those studies,it has been confirmed that plants derived antioxidants,particularly flavanoids,show a significant influence to block hepatic fibrosis regardless of any etiology.This review outlines recent progress in the use of plant derived drugs against experimentally induced liver fibrosis by in vitro and in vivo studies and summarizes the possible mechanisms anti-fibrotic effects of these compounds.