Inactivation of deubiquitinase CYLD enhances therapeutic antibody production in Chinese hamster ovary cells.

Chinese hamster ovary (CHO) cells are promising host engineering cells for industry manufacturing of therapeutic antibodies. However, cell death due to apoptosis remains a huge challenge to augment antibody production, and developing CHO cells with enhanced anti-apoptosis and proliferation ability is fundamental for cell line development and high-yielding bioprocesses. Deubiquitinase cylindromatosis (CYLD) has been proved to be a tumor suppressor by negatively regulating NF-κB and Wnt/β-catenin signaling pathways. Its mutation or deletion is a common chromosome variation in several types of cancers. Here, we engineered CHO CYLD-/- cells by CRISPR-Cas9 editing technology. These cells displayed stronger cell proliferation and anti-apoptosis ability compared to parental cells. Three antibody expression plasmid kits were transiently transfected into these cells. Our data showed that inactivation of CYLD increased the highest titers of rituximab, Herceptin, and one bispecific antibody by 105, 63, and 228%, respectively. Reversely, overexpression of CYLD could promote cell apoptosis, whereas inhibiting cell proliferation and antibody production. Furthermore, inhibition of CYLD in CHO cells stably expressing an IgG antibody (CHO-IgG) achieved about 50% increase in product titer compared to parental cells. Meanwhile, inhibition of CYLD did not affect the quality of antibody. Thus, our data demonstrated that inactivation of CYLD could promote CHO cell proliferation, anti-apoptosis ability, and subsequent antibody production, suggesting that CYLD is a potential functional target for CHO cell engineering.