title: Recombinant cyclin E expression activates proliferation and obviates surface attachment of chinese hamster ovary (CHO) cells in protein-free medium.
abstract: Exogenous growth factors normally required in cell culture activate cell proliferation via the molecular controls of cell-cycle progression. Highly differing influences of mitogenic stimulation of Chinese hamster ovary (CHO) cells by insulin and basic fibroblast growth factor(bFGF) have been clearly observed in a defined protein-free medium. CHO K1 cells stimulated only with insulin grow with flattened cell morphology and extensive cell-cell contact, whereas stimulation with only bFGF or bFGF plus insulin results in loss of cell-cell contact and a transformed and rounded-up morphology. Compared with insulin-stimulated cells, bFGF-stimulated cells exhibit a relatively long G1, and short S phase, and contain higher levels of cyclin E. Observation of elevated levels of cyclin E in wild-type CHO K1 cells mitogenically stimulated by basic fibroblast growth factor motivated transfection of these cells by a cyclin E expression vector. These transfectants grew rapidly in protein-free basal medium and had similar cyclin b levels, distributions of nuclear cell-cycle times, and cell morphologies as bFGF-stimutated CHO K1 culture. Metabolic engineering of cell-cycle regulation thus bypasses exogenous growth factor requirements, addressing a priority objective in economical, reproducible, and safe biopharmaceutical manufacturing. (c) 1995 John Wiley & Sons Inc.
authors.affiliation: Institute of Biotechnology, ETH Zürich, CH-8093 Zürich, Switzerland.
authors.forename: W A
authors.initials: WA
authors.lastname: Renner
authors.forename: K H
authors.initials: KH
authors.lastname: Lee
authors.forename: V
authors.initials: V
authors.lastname: Hatzimanikatis
authors.forename: J E
authors.initials: JE
authors.lastname: Bailey
authors.forename: H M
authors.initials: HM
authors.lastname: Eppenberger