Expression, Purification and Characterization of A Novel Soluble Human Thymosin Alpha1 Concatemer Exhibited A Stronger Stimulation on Mice Lymphocytes Proliferation and Higher Anti-tumor Activity

Thymosin alpha 1 (Tα1) has immunomodulatory and anti-tumor effects in patients and has been commercialized in worldwide. An innovative technique is therefore impending to achieve high-yield expression and purification of Tα1 to meet the increasing requirements for clinical applications. Tα1 can enhance T cells, dendritic cells and antibody responses, and also augment an anti-tumor immune response. In the current study, we developed a novel technique to produce Tα1 concatemer and investigated its capability in anti-tumor immunotherapy. We expressed the recombinant 2×Tα1 concatemer protein (Tα1② protein) in Escherichia coli. The purity of Tα1② was higher than 95% as assessed by HPLC analysis. In vitro, Tα1② could stimulate the proliferation of mouse splenic lymphocyte, and increase the apoptosis of tumor cell lines. In vivo, Tα1② significantly inhibited the tumor growth in B16 tumor-bearing mice. Compared with Tα1, the Tα1② is of more effective bioactivity than Tα1. The purified Tα1② is a promising substitute for synthetic Tα1 because of its potent anti-tumor effects. We concluded that the expression system for Tα1 concatemer was constructed successfully, which could serves as a highly efficient tool for the production of large quantities of the highly active protein.