Chinese hamster ovary (CHO) cells are widely used for constructing expression systems to produce therapeutic proteins. However, the establishment of high-producer clones remains a laborious and time-consuming process, despite various progresses having been made in cell line development. We previously developed a new strategy for screening high monoclonal antibody (mAb)-producing cells using flow cytometry (FCM). We also reported that p180 and SF3b4 play key roles in active translation on the endoplasmic reticulum, and that the productivity of secreted alkaline phosphatase was enhanced by the overexpression of p180 and SF3b4. Here, we attempted to apply the translational enhancing technology to high mAb-producing cells obtained after high-producer cell sorting. A high mAb-producing CHO clone, L003, which showed an mAb production level of3 g/L in fed-batch culture, was established from a high mAb-producing cell pool fractionated by FCM. Clones generated by the overexpression of p180 and SF3b4 in L003 cells were evaluated by fed-batch culture. The specific productivity of clones overexpressing these two factors was ∼3.1-fold higher than that of parental L003 cells in the early phase of the culture period. Furthermore, the final mAb concentration was increased to 9.5 g/L during 17 days of fed-batch culture after optimizing the medium and culture process. These results indicate that the overexpression of p180 and SF3b4 would be promising for establishing high-producer cell lines applicable to industrial production.
