Recombinant insulin-like growth factor-I (IGF-I) production in Super-CHO results in the expression of IGF-I receptor and IGF binding protein 3.

Previously, we described the genetic construction Super- CHO, a cell line capable of autocrine growth under fully defined protein-free conditions. Super-CHO cells constitutively express insulin growth factor-I (IGF-I) and transferrin in sufficient amounts to support long-term, stable growth without the addition of exogenous growth factors, thus making it an ideal host for the production of recombinant biopharmaceuticals. although IGF-I has been successfully expressed in Chinese Hamster Ovary (CHO) cells, the long term effects of recombinant IGF-I expression have not been explored.

Regulated autocrine growth of CHO cells.

The goal of this work was to engineer a CHO cell line capable ofautocrine growth in a fully defined protein-free medium. Thiswas accomplished by stable integration of the genes encodinginsulin-like growth factor I (IGF-I) and transferrin into thegenome of a CHO-K1 cell line. Thelac operator/repressorsystem was used to regulate the expression of the IGF-I gene with thelac operator sequence being placed upstream ofthe coding sequence for IGF-I.

Accelerated cell line development using two-color fluorescence activated cell sorting to select highly expressing antibody-producing clones.

The success of engineered monoclonal antibodies as biopharmaceuticals has generated considerable interest in strategies designed to accelerate development of antibody expressing cell lines. Stable mammalian cell lines that express therapeutic antibodies at high levels typically take 6-12 months to develop. Here we describe a novel method to accelerate selection of cells expressing recombinant proteins (e.

Epi-CHO, an episomal expression system for recombinant protein production in CHO cells.

This study describes the development of a transient expression system for CHO cells based on autonomous replication and retention of transfected plasmid DNA. A transient expression system that allows extrachromosomal amplification of plasmids permits more plasmid copies to persist in the transfected cell throughout the production phase leading to a significant increase in transgene expression. The expression system, named Epi-CHO comprises (1) a CHO-K1 cell line stably transfected with the Polyomavirus (Py) large T (LT) antigen gene (PyLT) and (2) a DNA expression vector, pPyEBV encoding the Py origin (PyOri) for autonomous plasmid amplification and encoding Epstein-Barr Virus (EBV) nuclear antigen-1 (EBNA-1) and OriP for plasmid retention.

Enhanced productivity of G1 phase Chinese hamster ovary cells using the GADD153 promoter.

Productivity of three different promoters at various cell cycle stages and under two distinct growth conditions was examined in Chinese hamster ovary cells. Under the Growth Arrest and DNA Damage inducible GADD153 promoter, productivity of the short half-live variant of the enhanced green fluorescent protein (d2EGFP) and the secreted alkaline phosphatase (SEAP) was highest at the G1 phase of the cell cycle and at serum starvation, while under the cytomegalovirus (CMV) or the simian virus SV40 promoter, productivity was highest at S-phase and in complete medium. These results indicate the utility of the GADD153 promoter for production purposes under protein-free conditions.