Molecular mechanisms underlying the α‑tomatine‑directed apoptosis in human malignant glioblastoma cell lines A172 and U‑118 MG
- Fa‑Zhao Wang
- Xue‑Liang Dai
- Hong‑Yi Liu
Published online on: October 12, 2017
In the present study, the molecular mechanisms involved in the α‑tomatine‑induced apoptosis in human glioblastoma cell lines A172 and U‑118 MG were investigated. Wright staining and ApopTag assays were conducted to confirm the apoptosis induced by α‑tomatine treatment. Fura‑2 assay determined an enhancement in free Ca2+ intracellularly, indicating the occurrence of Ca2+‑dependent apoptosis induction. Western blot experiments were also performed to predict the apoptosis by measuring the changes in the Bax:Bcl‑2 ratio. Increase of calpain activity triggered caspase‑12 expression, which in turn further activated caspase‑9. In addition, an increase in the ratio of Bax:Bcl‑2 accounted for the mitochondrial release of cytochrome c into the cytosol for caspase‑3 and caspase‑9 activation. Elevated activity of calpain and caspase‑3 yielded spectrin breakdown products with 145 and 120 kDa, respectively. Caspase‑3 activation further cleaved the inhibitor of caspase activated DNase, while the apoptosis‑inducing factor detected in the cytosol suggested that apoptosis was independent of caspase. The apoptosis induction was further supported by decreased expression levels of nuclear factor‑κB and increased expression of the inhibitor of nuclear factor, IκBα. In conclusion, the presented experimental results revealed the stimulation of different molecular mechanisms for α‑tomatine‑mediated apoptosis in A172 and U‑118 MG human glioblastoma cell lines.