Actin-sequestering protein, thymosin beta-4, induces paclitaxel resistance through ROS/HIF-1 alpha stabilization in HeLa human cervical tumor cells

作者：Oh Jin Mi; Moon Eun Yi^*

来源：Life Sciences, 2010, 87(9-10): 286-293.

DOI：10.1016/j.lfs.2010.07.002

• Thymosin beta-4
• HIF-1 alpha
• ROS
• Paclitaxel
• Resistance

Aims: We investigated whether actin-sequestering protein, thymosin beta-4 (TB4)-induced reactive oxygen species (ROS) affect the stabilization of hypoxia-inducible transcription factor (HIF)-1 alpha and paclitaxel-resistance induction.
Main methods: HeLa human cervical tumor cells were used. The percentage of cell survival was determined by MU assay. ROS production, cell cycle and hypodiploid cell formation were assessed by flow cytometry analysis. HIF-1 alpha stabilization and molecular changes were analyzed by western blotting or RT-PCR. NF-kappa B activation was assessed by EMSA and western blotting.
Key findings: T84 protein (TB4P) significantly increased intracellular ROS level and HIF-1 alpha. The increased level of HIF-1 alpha by TB4P was reduced by the treatment with N-acetylcysteine (NAC), a well-known ROS scavenger. TB4P-induced ROS production was confirmed by the activation of nuclear factor kappa B. TB4P-induced Erk phosphorylation was attenuated by the treatment with NAC. In addition, tumor cell death was decreased by 184 gene overexpression and TB4P treatment. NAC treatment attenuated tumor cell density increased by TB4P. Tumor cell death by paclitaxel was also increased by NAC treatment or the transfection with HIF-1 alpha-siRNA. Paclitaxel-induced B16F10 mouse melanoma regression was physiologically inhibited in TB4-transgenic mice compared to wildtype mice.
Significance: These findings demonstrate that TB4-induced ROS and ROS-mediated HIF-1 alpha stabilization could play a role in tumor cell resistance to anticancer agents like paclitaxel. It suggests that soluble TB4 could be a novel endogenous regulator to control intracellular ROS production in tumor cells.

• 出版日期2010-8-28