Microarray expression profiling identifies genes regulating sustained cell specific productivity (S-Qp) in CHO K1 production cell lines

Fed batch culture processes are often characterized by decreasing cell culture performance as the process continues, presumably through the depletion of vital nutrients and the accumulation of toxic byproducts. We have similarly observed that cellular productivity (Qp) often declines during the course of a fed batch process; however, it is not clear why some cell lines elicit this behavior, while others do not. We here present a transcriptomic profiling analysis of a phenotype of sustained Qp (S-Qp) in production Chinese hamster ovary (CHO) culture, in which a marked drop in Qp levels ("non-sustained" (NS) phenotype) in two cell lines irrespective of viability levels was compared to two cell lines that consistently displayed high Qp throughout the culture ("sustained" (S) phenotype). Statistical analysis of the microarray data resulted in the identification of 22 gene transcripts whose expression patterns were either significantly negatively or positively correlated with long-term maintenance of Qp over the culture lifespan. qPCR analysis of four of these genes on one of each (NS2, S2) of the cell lines examined by microarray analysis confirmed that two genes (CRYAB and MGST1) both replicated the microarray results and were differentially regulated between the NS and S phenotypes.