Stathmin Is Involved in Arsenic Trioxide-Induced Apoptosis in Human Cervical Cancer Cell Lines via PI3K Linked Signal Pathway

Cancer Biol Ther. 2010 Sep 15;10(6):632-43. doi: 10.4161/cbt.10.6.12654. Epub 2010 Sep 13.

Abstract

Although the mechanisms of arsenic trioxide (As2O3)-induced apoptosis have been elucidated extensively in hematologic cancers, those in solid tumors have yet to be clearly defined. In the present study, we show that As2O3 triggers apoptosis through the intrinsic pathway and significantly downregulates stathmin expression. Decreased stathmin expression is necessary for the dissipation of mitochondrial membrane potential (Δ ψm), the translocation of cytochrome C from the mitochondria to the cytosol, and subsequent cell death. Overexpression of wild type stathmin effectively delays As2O3-mediated mitochondrial events. Conversely, expression of a small interfering RNA (siRNA) targeting stathmin enhances As2O3-triggered apoptosis in cell culture and in mouse models. Furthermore, we demonstrate that As2O3-induced stathmin downregulation is mediated through the phosphatidylinositol-3-kinase (PI3K) signaling pathway, and that a PI3K inhibitor effectively attenuated stathmin downregulation and cell apoptosis upon As2O3-treatment. These data support a stathmin-dependent pathway of As2O3-mediated cell death in solid tumor cells, and indicate that stathmin is a target of the PI3K/Akt pathway in cervical cancer cells. All these results may provide a rationale for improving the efficacy of As2O3 as a therapeutic agent through combination treatment with stathmin inhibition or PI3K/Akt inhibitors.

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology
  • Apoptosis / drug effects*
  • Arsenic Trioxide
  • Arsenicals / pharmacology*
  • Blotting, Western
  • Cell Line, Tumor
  • Female
  • HeLa Cells
  • Humans
  • In Situ Nick-End Labeling
  • Membrane Potential, Mitochondrial / drug effects
  • Mice
  • Mice, Inbred BALB C
  • Mice, Nude
  • Oxides / pharmacology*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Proto-Oncogene Proteins c-akt / metabolism
  • RNA Interference
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / drug effects
  • Stathmin / genetics
  • Stathmin / metabolism*
  • Survival Analysis
  • Tumor Burden / drug effects
  • Uterine Cervical Neoplasms / drug therapy*
  • Uterine Cervical Neoplasms / metabolism
  • Uterine Cervical Neoplasms / pathology
  • Xenograft Model Antitumor Assays

Substances

  • Antineoplastic Agents
  • Arsenicals
  • Oxides
  • Stathmin
  • Phosphatidylinositol 3-Kinases
  • Proto-Oncogene Proteins c-akt
  • Arsenic Trioxide