Effect Of Curcumin On Expression Of P-ERK1/2and P-p38MAPK In Hepatocellular Carcinoma HepG2Cells

Objective:Hepatocellular carcinoma (HCC) is one of the most commonmalignant tumor in the worldwide.It is the fifth most common cancer in menand the seventh in women. Its incidence is continuously increasing, and overthe past20years, the incidence rate has increase three times. Each year,hepatocellular carcinoma is diagnosed in more than half a million peopleworldwide, while the5-year survival rate has remained below12%. Humanhealth is threatened by hepatocellular carcinoma seriously. Most of the burdenof disease (85%) is borne in developing countries and regions, includingSoutheast Asia and sub-Saharan Africa where infection with hepatitis B virus(HBV) is endemic. In addition to preventing the spread of hepatitis B virus, weneed to find an effective anticancer drugs to control the development ofhepatocellular carcinoma.Curcumin is a polyphenolic compound, which is extracted from therhizomes of Curcuma-Turmeric. Curcumin is the main component of Curcumalonga. The important role of curcumin is anti-inflammatory, antioxidant, anti-toxicant, anticoagulant, and lipid-lowering,anti-atherosclerotic. Recent studiesfound that curcumin has anti-tumor effect, and can inhibit most tumorproliferation and promote apoptosis, including hepatocellular carcinoma, lungcancer, breast cancer, colorectal cancer and so on.Mitogen-activated protein kinases (MAPKs) are serine/threonine proteinkinase, which exist in most cells, including ERK1/2(extracellular signal-regulated protein kinase1/2), p38MAPK(p38mitogen activated proteinkinases), JNK/SAPK(C-Jun NH₂-terminal kinase/stress activated proteinkinase). With the extracellular signals stimulating,these pathways are activated.They can regulate growth, proliferation, differentiation and apoptosis. Inrecent years, studies show that MAPKs pathway play an important role occurrence and development process of tumor.Studies have shown that curcumin can significantly activate p38MAPKpathway by phosphorylation, but not the ERK signaling pathway in humanovarian cancer cells during the process of apoptosis. Curcumin can inhibittumor invasion of oral squamous cell carcinoma by inhibition of the ERKsignaling pathway. However, another researchers have found that curcumincan activate MAPKs, including ERK pathway in MDA-MB-435breast cancercells. The relationship between curcumin and MAPKs pathway is uncertain,especially very little research on ERK1/2and p38MAPK signal transductionpathway. In hepatocellular carcinoma, the ERK1/2and p38MAPK play acrucial role, and whether curcumin affect proliferation and apoptosis willcontribute to the exploit of drug treating hepatocellular carcinoma.So, our study will investigate whether curcumin can inhibit the growthand proliferation of human hepatocellular carcinoma HepG2cells, observe theeffect of curcumin on expression of p-ERK1/2and p-p38MAPK.Then analyzewhether curcumin can inhibit cell proliferation through ERK and p38MAPKsignaling pathway in HepG2Cells.Thus, it provides more theoretical basis forthe treatment of hepatocellular carcinoma.Method:Cultivate hepatocellular carcinoma cell line HepG2in general.Inhibition of different curcumin concentrations (10μmol/L,20μmol/L,30μmol/L,40μmol/L,50μmol/L) for24h,48h and72h to HepG2cells proliferation wasdetected by MTT. Expression of p-ERK1/2and p-p38MAPK in HepG2cellsunder the effect of different curcumin concentrations (10μmol/L,20μmol/L,30μmol/L,40μmol/L and50μmol/L) and different times (15min,30min,60min)was detected by Western-Blotting.Results:1MTT results revealed that curcumin can significantly inhibit theproliferation of HepG2cells, with a time-and dose-dependent manner(P<0.05).2Western-Blotting results revealed that after HepG2cells are treatmentedwith different concentrations of curcumin (10μmol/L,20μmol/L,30μmol/L, 40μmol/L,50μmol/L) for30min, the expression of p-ERK1/2is decreasedsignificantly(P<0.05),while there is no difference between40μmol/L and50μmol/L groups(P＞0.05).When HepG2cells are treated with30μmol/Lcurcumin for different times(15min,30min,60min), the expression ofp-ERK1/2is decreased significantly(P<0.05), and60min group is the lowest,compared with control group.3Western-Blotting results revealed that after HepG2cells are treatmentedwith different concentrations of curcumin (10μmol/L,20μmol/L,30μmol/L,40μmol/L,50μmol/L) for30min, the expression of p-p38MAPK is increasedsignificantly(P<0.05).There is no difference between10μmol/L and20μmol/Lgroups,30μmol/L and40μmol/L groups (P＞0.05),while50μmol/L groups ishigher than control and other groups markedly(P<0.05).When HepG2cells aretreated with30μmol/L curcumin for different times(15min,30min,60min), theexpression of p-p38MAPK is increased significantly(P<0.05), and60mingroup is the highest(P<0.05), compared with control group.Conclusion: Curcumin can inhibit Human Hepatocellular CarcinomaHepG2cells proliferation; in HepG2cells,curcumin can down-regulate theexpression of p-ERK1/2,blok ERK1/2signaling pathway and up-regulatep-p38MAPK, activate p38MAPK signaling pathway.