Expression and Purification of a Putative Tumor Suppressor Gene PP5715 in E. coli with Growth Inhibition of Hepatocellular Carcinoma Cells

PP5715 is a putative tumor suppressor gene that encodes a protein of 199 amino acids. Expression of PP5715 in E. coli was mainly as inclusion bodies. The recombinant protein was purified by a NTA-Ni2+ affinity column, refolded by dialysis, and shown to suppress growth of two human hepatocellular carcinoma cell lines using the MTT assay or the clonogenic assays. Computer analysis and fusion expression of PP5175 and GFP showed that PP5715 may be a secretory protein. It may bind to receptors on the membrane surface and thus induce regulation of cell growth. These preliminary results suggest that protein PP5715 may be a new tumor suppressor with growth inhibition effects on hepatocellular carcinoma cells.