Increased hCTLA4-Ig production by regulating feeding time of 4-phenylbutyrate in CHO cell cultures

초록

Most of the therapeutic proteins are produced from Chinese hamster ovary (CHO) cell line. Small molecule enhancers have been applied for enhancing protein productivity. Among them, 4-phenylbutyrate (4-PBA) is known to enhance the production of recombinant proteins in mammalian cell culture, but it can also inhibit cell growth and induce cellular apoptosis. It shows cytotoxicity when it is added in culture medium. In this study, we controlled the feeding time of 4-PBA to minimize cytotoxicity and prolong the culture period by reducing adverse effects on cell growth. Improved cell growth enhanced the production of hCTLA4-Ig. Three concentrations (0.5, 1 and 2 mM) of 4-PBA were added with initial feeding, exponential phase feeding and interval feeding. When 0.5 mM 4-PBA was added in culture medium with interval feeding, the highest titer was obtained compared to other conditions along with prolonged culture period. When analyzing cell cycle distribution, G1 phase, which is related to protein synthesis, was found to be the largest proportion when 0.5 mM 4-PBA was added with interval feeding. Moreover, each feeding time showed different cell cycle arrest pattern, the proportion of cell cycle could be controlled by regulating 4-PBA feeding time. It was proved that controlling feeding time of cell cycle inhibitors can improve the production of hCLTA4-Ig. In conclusion, controlling feeding time of 4-PBA can effectively increase the production of target protein.