Regulation of Cell Cycle and Productivity in NS0 Cells by the Over-Expression of p21^CIP1

Abstract

The improvement of cellular activities by cell (metabolic) engineering of enzymatic, transport and regulatory functions has been widely accepted as a way forward for integrated process development. We report here for the first time the successful construction of anchorage- independent and proliferation-controlled NS0 cell lines with enhanced secreted chimeric antibody expressed from a constitutive promoter. The LacSwitch system, which relies on, vectors containing a hybrid RSV-LTR and Lac operator was used to rapidly induce expression of p21^CIP1 in cells by addition rather than removal of agent to cause induction. The effect of various levels of p21^CIP1 expression on cell proliferation, cell cycle, apoptosis and cB72.3 antibody productivity was assessed. The data shows an excellent correlation between levels of induced p21^CIP1 protein, cell cycle arrest and increased antibody expression. Rates of apoptosis were not significandy affected and cells were able to survive in a cytostatic state with significantly improved productivity for a prolonged period.