Razi Journal of Medical Sciences

Background: Cultivated mammalian cells, because of their capacity for proper protein folding, assembly and post–translational modification, have become the dominant system for production of recombinant proteins in clinical application. Therefore, the quality and efficacy of protein can be superior when expressed in mammalian cells compared to other hosts such as bacteria. Gene reporter systems have contributed greatly to the study of eukaryotic gene expression and regulation. Although reporter genes have played a significant role in numerous applications, both in vitro and in vivo, they are most frequently used as indicators of transcriptional activity in cells. Luciferase-reporter assays are widely used to monitor the cellular events related to transduction and gene expression regulated by specific cascades, such as PRL/Jak2/Stat5 pathway.

Methods: In this study, recombinant human growth hormone (rhGH) was produced in eukaryotic Chinese hamster ovary (CHO) cell and production and concentration of rhGH verified by ELISA and western blotting. Then, the biological activity of rhGH was assessed by a gene reporter assay system (containing LHRE, TK promoter and Luc gene), using HEK 293 cells transfected with GH receptor and response element for STAT-5 measuring luciferase activity on a Berthold luminometer.

Results: The date showed that rhGH could be produced by eukaryotic host in good quantities as assessed by ELISA and western blotting. The results of gene reporter assay showed that rhGH produced by CHO cells is able to induce GH intracellular cell signaling. The rhGH produced by CHO cells showed higher bioactivity when compared to commercial GH.

Conclusion: rhGH could be produced in mammalian cell lines at high levels with higher bioactivity. Gene reporter assay is a sensitive, quantitative, rapid, easy, reproducible and safe system for assessment of bioactivity of recombinant proteins such as rhGH.