A CHO-Derived Matrix Attachment Region Enhances Transgene Dosage, SATB1 Recruitment, and Monoclonal Antibody Expression in a Dual-Promoter Vector System.

Abstract

The production of monoclonal antibodies (mAbs) in Chinese hamster ovary (CHO) cells is often affected by position-effect variegation and the gradual loss of transgene expression over time. Hence, we have designed a dual-promoter IgG expression vector and compared versions that either contained or lacked a CHO-derived matrix-attachment region (MAR). Stable CHO-S pools, cultured in serum-free conditions, revealed that the MAR-containing construct produced higher and more consistent antibody levels across ten passages, as confirmed by Western blot and Protein A Octet analysis. Product-quality analysis by size-exclusion chromatography and reducing SDS-PAGE confirmed formation of properly assembled, mainly monomeric antibodies in both cases. Quantitative PCR indicated greater transgene copy numbers in MAR pools (+ 48% for the light chain and + 71% for the heavy chain), and RT-qPCR showed roughly fourfold higher transcript levels for both chains relative to controls. Bioinformatic analysis revealed several SATB1 binding motifs within the MAR sequence, and ChIP-qPCR demonstrated SATB1 association with the MAR-linked transgene locus. Overall, the data suggested that a CHO-native MAR could enhance transgene dosage and transcriptional activity, while preserving product integrity, possibly through SATB1-mediated chromatin organization. Ongoing work includes chromatin-mark profiling and process-level productivity measurements to better define the impact of MAR-based vector design on biomanufacturing performance.