EXPRESSION OF SECRETED RECOMBINANT HUMAN INSULIN-LIKE GROWTH FACTOR-II (IGF-II) IN CHINESE-HAMSTER OVARY CELLS

Chinese hamster ovary (CHO-KI) cells were cotransfected with a plasmid pcDNAI containing the human preproinsulin-like growth factor II cDNA linked downstream to the human cytomegalovirus promoter and with a pla smid containing the neomycin resistance gene (pMAM-neo). CHO neo(+) we re selected by growth in medium supplemented with G418 geneticin. Afte r amplification, the neomycin-resistant clones were screened for IGF-I I production. IGF-II produced was identified by dot blot and quantifie d by ELISA. The clones C24, C40 and C94 secreted IGF-II at about 350-4 00 ng per 10(6) cells per day. DNA analysis of C24 and C40 CHO cells b y PCR demonstrated the presence of the IGF-II construct in the transfe cted cells, presumably integrated into the chromosomal DNA. IGF-II pro duced by CHO cells and purified by RP-HPLC was a mitogen for MCF-7 sti mulating mitosis 2-fold.