Contribution Of ERK Pathway To The Curative Effect Of Curcumin On Human Glioma U251 Cells

Objective:To investigate the effect of curcumin on the proliferation, differentiation,invasion and angiogenesis of human glioma U251 cells in vitro and in vivo and the role of ERK pathway during this process.Methods:1 We treated U251 cells with curcumin,examined the cell viability by MTT assay and worked out the IC50. U251 cells were randomly assigned into two groups:the control group and the drug group with curcumin treatment. The plate clony efficiency was determined by clony formation assay. The morphology difference of U251 cells was determined by inverted microscope. The cell cycle distribution was determined by flow cytometry. Transwell invasion assay was used to measure the invasive ability of U251 cells .The expression of PCNA,c-fos,GFAP,vimentin,MMP-9,VEGF,Ets-1,ERK and pERK were measured by immunocytochemistry or Western blot analysis.2 We treated U251 cells with PD98059, examined the cell viability by MTT assay and worked out the IC50. U251 cells were randomly assigned into two groups:the control group and the drug group with PD98059 treatment. The expression of c-fos,GFAP,MMP-9,Ets-1,ERK and pERK were measured by immunocytochemistry or Western blot analysis.3 We established a nude mouse model of human glioma U251 cells by subcutaneous implantation. The glioma-bearing mice were randomly assigned into 2 groups:the control group and the drug group with curcumin intraperitoneal injection. The tumor volume inhibition rate and the weight inhibition rate were calculated respectively. The expression of ERK and pERK were assessed by Western blot analysis. 4 We established a nude mouse model of human glioma U251 cells by intracerebral implantation. The glioma-bearing mice were randomly assigned into 2 groups: the control group and the drug group .The glioma-bearing mice had been treated with curcumin intraperitoneally or intratumorally. The tumor volume inhibition rate was calculated. In the intratumoral injection test,the expression of ERK and pERK were assessed by Western blot analysis.Results:1 Curcumin inhibited the proliferation of U251 cells in a dose dependent manner. The IC50 was 16μmol/L. Curcumin treatment resulted in decreased clony efficiency. The cell processes turned longer and slimmer.The cell percentage in phase s decreased. The number of cells went through the basal membrane was lowered. The expression of PCNA,c-fos,vimentin,MMP-9,VEGF,Ets-1 and pERK decreased. The expression of GFAP increased, while the expression of total ERK showed no difference.2 PD98059 inhibited the proliferation of U251 cells in a dose dependent manner. The IC50 was 25μmol/L. The expression of c-fos,MMP-9,Ets-1 and pERK decreased. The expression of GFAP increased, while the expression of total ERK showed no difference.3 We successfully established a nude mouse model of human glioma U251 cells by subcutaneous implantation.Curcumin intraperitoneal injection inhibited the growth of U251 glioma cells in nude mice. The tumor volume and weight decreased significantly. The expression of pERK decreased. The expression of total ERK showed no difference.4 We successfully established a nude mouse model of human glioma U251 cells by intracerebral implantation. In the intraperitoneal injection test, the volume of implanted tumor decreased with the treatment of curcumin,but with no statistic difference. In the intratumoral injection test,however, the volume of implanted tumor decreased with marked statistic difference. The expression of pERK decreased. The expression of total ERK showed no difference. Conclusions:1 Curcumin may inhibit the proliferation,invasion,angiogenesis and induce differentiation of human glioma U251 cells in vitro. This effect may result from the blocking of ERK pathway.2 Curcumin intraperitoneal injection may inhibit the growth of U251 glioma cells subcutaneously implanted in nude mice. The blocking of ERK pathway may be involved in the inhibition process.3 Intraperitoneal injection with curcumin has no effect on the growth of implanted tumor in brain. Curcumin inhibits the growth of U251 glioma cells in nude mice brain when it is injected intratumorally,which may also be due to the blocking of ERK pathway.