Leveraging ANXA1 to enhance recombinant protein yields in CHO cells: A UPR-Mediated bioprocessing approach

Chinese hamster ovary (CHO) cells undergo endoplasmic reticulum stress (ERS) during intensive recombinant protein production, triggering the unfolded protein response (UPR) to balance cell survival and protein output. Nevertheless, key regulatory components of this process remain incompletely characterized. In this study, we demonstrate that Annexin A1 (ANXA1) functions as a UPR suppressor in CHO cells. Employing the PiggyBac transposon system, we generated a stable ANXA1-knockdown cell line exhibiting a 4.5-fold increase in recombinant antibody expression and a 4.2-fold increase in specific productivity. Pharmacological inhibition using AC2-26 similarly enhanced recombinant protein expression in low-productivity cell populations. Mechanistically, ANXA1 depletion remodeled the UPR by activating the PERK-eIF2α-ATF4 and IRE1-XBP1 branches. This activation upregulaed ATF4, Bip, and XBP1s; suppressed CHOP; reduced apoptosis; and enhanced autophagic flux. Metabolic profiling revealed increased glucose and lactate utilization, while glutamine consumption and ammonia flux remained unchanged. Collectively, these findings establish that ANXA1 depletion enhances recombinant protein biosynthesis through coordinated pro-survival mechanisms. Targeting ANXA1 thus represents an innovative cell engineering strategy for optimizing CHO cell platforms in industrial biopharmaceutical manufacturing.