A new Chinese hamster ovary cell line expressing α2,6-sialyltransferase used as universal host for the production of human-like sialylated recombinant glycoproteins

Chinese hamster ovary (CHO) cells are widely employed to produce glycosylated recombinant proteins. Our group as well as others have demonstrated that the sialylation defect of CHO cells can be corrected by transfecting the alpha 2,6-sialyltransferase (alpha 2,6-ST) cDNA. Glycoproteins produced by such 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 for 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 expression was stable in the absence of selective pressure, that the recombinant sialyltransferase was correctly localized in the Golgi and, finally, that the bioreactor growth parameters of the universal host were comparable to those of the parental cell line. A second step consisted in the stable transfection into the universal host of cDNAs for human glycoproteins of therapeutic interest, i.e. interferon-gamma and the tissue inhibitor of metalloproteinases-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 produced by normal CHO cells. (C) 2000 Elsevier Science B.V. All rights reserved.