title: CHO cell culture longevity and recombinant protein yield are enhanced by depletion of miR-7 activity via sponge decoy vectors.
abstract: Improving the efficiency of recombinant protein production by CHO cells is highly desirable as more complex proteins (MAbs, fusion proteins, blood/clotting factors, etc.) go into development and come onto the market. Previous reports have shown that microRNA (miRNA)-7 overexpression arrests the growth of CHO cells and that its depletion increases the proliferation of various cell types. In this study we generated stable CHO clones that overexpressed a miR-7-specific decoy transcript (sponge) downstream of a green fluorescent protein reporter gene. The miR-7 sponge efficiently diverted miR-7 away from its endogenous targets as exemplified by the increased expression of CDC7. Although the sponge effectively sequestered miR-7, it also appeared to protect the bound miRNA sequence from degradation in the cell, as exemplified by the apparent increase in mature miR-7 levels without any change in primary transcription. Phenotypically, CHO clones with sequestered miR-7 displayed improved maximum cell density (40%), significantly improved viability and an almost two-fold increase in yield of secreted protein in a fed-batch culture. These findings demonstrate that miRNA sponge transcripts could potentially be used in cell line development projects to generate producer clones that grow to higher densities and last longer in the bioreactor - thereby improving product yield.
authors.affiliation: National Institute for Cellular Biotechnology, Dublin City University, Dublin, Ireland.
authors.forename: Noelia
authors.initials: N
authors.lastname: Sanchez
authors.forename: Paul
authors.initials: P
authors.lastname: Kelly
authors.forename: Clair
authors.initials: C
authors.lastname: Gallagher
authors.forename: Nga T
authors.initials: NT
authors.lastname: Lao
authors.forename: Colin
authors.initials: C
authors.lastname: Clarke
authors.forename: Martin
authors.initials: M
authors.lastname: Clynes
authors.forename: Niall
authors.initials: N
authors.lastname: Barron
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D019149:Bioreactors; D016466:CHO Cells; D002452:Cell Count; D018929:Cell Culture Techniques / Q000379:methods; D006224:Cricetinae; D003412:Cricetulus; D005822:Genetic Vectors; D008136:Longevity / Q000235:genetics*; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; C549243:MIRN7 microRNA, mouse; D035683:MicroRNAs; D011994:Recombinant Proteins
keywords: Biopharmaceutical production; Chinese hamster ovary; Target mediated miRNA protection; miRNA; miRNA sponge