Sulforaphane-cysteine Induces Cell Apoptosis And Inhibits Migration And Invasion In Human Glioblastoma Cells

Background and Aim: Glioblastoma is a common and aggressive brain tumor.The standard therapeutic way to treat this disease is to use a surgical resection followed by a combination of radiotherapy and/or chemotherapy.However,glioblastoma cells often generate resistance to temozolomide(TMZ),a commonly used drug,leading to a low average survival time for patients after general treatment,which is approximately 15 months.Therefore,it is high time to find out a more efficient drug.Studies showed that sulforaphane(SFN)obtained from cruciferous vegetables inhibited a variety of tumors.We previously demonstrated that sulforaphane(SFN)inhibited invasion via sustained activation of ERK1/2 in human glioblastoma cells.However,sulforaphane-cysteine(SFN-Cys),an analogue of SFN,enriched in plasma with longer half-life,had more potentiality to induce apoptosis.Here we investigated the molecular mechanisms of SFN-Cys-induced apoptosis in human glioblastoma U373 MG and U87 MG cells.Methods and Results: Cell proliferation assay showed that SFN-Cys inhibited cell viability via a dose-dependent manner.Cell morphology observation also showed SFN-Cys increased the phenotype of cell death via a dose-dependent manner.Further,flow cytometry assay showed that SFN-Cys induced apoptosis significantly via a dose-dependent manner in both cell lines.Furthermore,Western blot analysis demonstrated that SFN-Cys induced activation of ERK1/2 via a sustained manner and the activation contributed to upregulation of Bax/Bcl-2 ratio and cleaved Caspase3,and these results can be reversed by ERK1/2 blocker PD98059.JC-1 mitochondrial membrane potential(MMP)assay showed that SFN-Cys downregulated MMP in U373 MG and U87 MG cells,and these results were reversed by ERK1/2 blocker PD98059.Conclusions: SFN-Cys induced intrinsic cell apoptosis via activation of ERK1/2 and the ERK1/2 mediated signaling pathways such as upregulation of Bax/Bcl-2 ratio and activation of Caspase-3.These discoveries indicated that SFN-Cys might be a more promising therapeutic agent versus SFN to resist glioblastoma cells,especially in Taxol resistant cancer cells.Background and Aim: Glioblastoma is known for its high invasion ability.Through surgery and/or radio/chemo-therapy,good effects have not been obtained yet.Patients after general treatment get a low average survival time,which is approximately 15 months.Our previous study showed that Sulforaphane(SFN),obtained from cruciferous vegetables,inhibited cell invasion in glioblastoma cells and prostate cancer cells,bringing hopes to glioblastoma sufferers.Sulforaphane-cysteine(SFN-Cys),an SFN analog and a metabolite of SFN as well,has more prominent advantages.SFN-Cys can penetrate the blood-brain barrier with a longer half-life compared with SFN.Therefore,we investigate the mechanisms of migration and invasion in glioblastoma U373 MG and U87 MG cells,providing more choices for glioblastoma treatment.Methods and Results: The scratch assay and Transwell assay showed that SFN-Cys inhibited U373 MG and U87 MG cell migration and invasion in a dose-dependent manner,and this inhibition ability could be mediated via activation of ERK1/2 signaling pathway.Western blot analysis demonstrated that SFN-Cys induced activation of ERK1/2 via a dose-dependent manner and the activation contributed to downregulation of α-tubulin and Stathmin-1 and to upregulation of p Stathmin-1(Ser 25),and these results can be reversed by ERK1/2 blocker PD98059.Further,immunofluorescence staining showed that SFN-Cys-mediated downregulation of α-tubulin led to microtubule disruption and a “nestlike” morphology change.Confocal microscopy observation showed that SFN-Cys downregulated Stathmin-1 expression rather than deprived the ability of Stathmin-1 binding to α-tubulin.Conclusions: SFN-Cys inhibited cell migration and invasion via activation of ERK1/2 and the ERK1/2 mediated signaling pathways such as downregulation of α-tubulin and Stathmin-1,and upregulation of p Stathmin-1(Ser 25).Taken together,SFN-Cys is an effective agent with low toxicity,and might bring hopes to glioblastoma patients.