A new Chinese hamster ovary cell line expressing alpha 2,6-sialyltransferase used as universal host for the production of human-like sialylated recombinant glycoproteins

Chinese hamster ovary (CHO) cells are widely employed to produce glycosylat ed recombinant proteins. Our group as well as others have demonstrated that the sialylation defect of CHO cells can be corrected by transfecting the a lpha 2,6-sialyltransferase (alpha 2,6-ST) cDNA. Glycoproteins produced by s uch CHO cells display both alpha 2,6- and alpha 2,3-linked terminal sialic acid residues, similar to human glycoproteins. Here, we have established a CHO cell line stably expressing alpha 2,6-ST, providing a universal host fo r further transfections of human genes. Several relevant parameters of the universal host cell line were studied, demonstrating that the alpha 2,6-ST transgene was stably integrated into the CHO cell genome, that transgene ex pression was stable in the absence of selective pressure, that the recombin ant sialyltransferase was correctly localized in the Golgi and, finally, th at the bioreactor growth parameters of the universal host were comparable t o those of the parental cell line. A second step consisted in the stable tr ansfection into the universal host of cDNAs for human glycoproteins of ther apeutic interest, i.e. interferon-gamma and the tissue inhibitor of metallo proteinases-l. Interferon-gamma purified from the universal host carried 40 .4% alpha 2,6- and 59.6% alpha 2,3-sialic acid residues and showed improved pharmacokinetics in clearance studies when compared to interferon-gamma pr oduced by normal CHO cells. (C) 2000 Elsevier Science B.V. All rights reser ved.