Rives Dyllan, Richbourg Tara, Gurtler Sierra, Martone Julia, Blenner Mark A
Department of Chemical & Biomolecular Engineering, Clemson University, 206 S. Palmetto Blvd., Clemson, SC 29634, USA.
Department of Chemical & Biomolecular Engineering, University of Delaware, 590 Avenue 1743, Newark, DE 19713, USA.
Int J Mol Sci. 2025 Jul 25;26(15):7189. doi: 10.3390/ijms26157189.
Chinese hamster ovary (CHO) cells are the most common protein production platform for glycosylated biopharmaceuticals due to their relatively efficient secretion systems, post-translational modification (PTM) machinery, and quality control mechanisms. However, high productivity and titer demands can overburden these processes. In particular, the endoplasmic reticulum (ER) can become overwhelmed with misfolded proteins, triggering the unfolded protein response (UPR) as evidence of ER stress. The UPR increases the expression of multiple genes/proteins, which are beneficial to protein folding and secretion. However, if the stressed ER cannot return to a state of homeostasis, a prolonged UPR results in apoptosis. Because ER stress poses a substantial bottleneck for secreting protein therapeutics, CHO cells are both selected for and engineered to improve high-quality protein production through optimized UPR and ER stress management. This is vital for optimizing industrial CHO cell fermentation. This review begins with an overview of common ER-stress related markers. Next, the optimal UPR profile of high-producing CHO cells is discussed followed by the context-dependency of a UPR profile for any given recombinant CHO cell line. Recent efforts to control and engineer ER stress-related responses in CHO cell lines through the use of various bioprocess operations and activation/inhibition strategies are elucidated. Finally, this review concludes with a discussion on future directions for engineering the CHO cell UPR.
中国仓鼠卵巢（CHO）细胞是糖基化生物制药中最常用的蛋白质生产平台，这是因为它们具有相对高效的分泌系统、翻译后修饰（PTM）机制和质量控制机制。然而，对高产量和高滴度的要求可能会使这些过程不堪重负。特别是，内质网（ER）可能会被错误折叠的蛋白质淹没，从而引发未折叠蛋白反应（UPR），这是内质网应激的证据。UPR会增加多种基因/蛋白质的表达，这有利于蛋白质折叠和分泌。然而，如果应激的内质网无法恢复到稳态，长时间的UPR会导致细胞凋亡。由于内质网应激是分泌蛋白治疗药物的一个重大瓶颈，因此CHO细胞既要经过筛选，也要进行基因工程改造，以通过优化UPR和内质网应激管理来提高高质量蛋白质的产量。这对于优化工业CHO细胞发酵至关重要。本综述首先概述了常见的内质网应激相关标志物。接下来，讨论了高产CHO细胞的最佳UPR特征，以及任何给定重组CHO细胞系的UPR特征的背景依赖性。阐明了最近通过使用各种生物工艺操作和激活/抑制策略来控制和改造CHO细胞系中内质网应激相关反应的努力。最后，本综述以对CHO细胞UPR工程未来方向的讨论作为结尾。
