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In Vitro Synthesis and Secretion of Glycoprotein by Human Mammary Tissue

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Journal In Vitro
Date 1978 Sep 1
PMID 721104
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Abstract

Organ cultures of human surgical specimens can be used to investigate glycoprotein production in vitro under conditions in which three-dimensional tissue structures and cell-cell interactions resemble those present in vivo. In this report, an organ-culture system is used to investigate the synthesis, transport and release of glycoprotein by normal and benign hyperplastic human mammary epithelium. Autoradiography of explants pulse-labeled with individual glycoprotein precursors ([3H]glucosamine, [3H]fucose, [3H]acetylmannosamine) and maintained in organ culture for intervals up to 72 hr revealed that glycoprotein is synthesized and then secreted by mammary epithelium. Incorporation of each isotope took place in the Golgi apparatus. Most of the newly synthesized glycoprotein, labeled with each of the three precursors, then was transported to apical cell surfaces and secreted into gland lumina. Observations were indistinguishable in normal and benign hyperplastic glands. Thus nonlactating human mammary epithelium exhibits a glycoprotein secretory activity. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of [3H]glucosamine-labeled macromolecules released into the medium showed a group of glycoproteins with a molecular weight of 48,000 +/- 6,000 daltons plus high-molecular-weight glycosylated components at the top of gels. The nature of gp48 is not known, but similar molecular-weight glycoproteins also are released by surgical specimens of human mammary cancer maintained in organ culture.

References
1.
Flaxman B, Dyckman J, Feldman A . Effect of prolactin on maintenance of prelactating human mammary gland in vitro. In Vitro. 1976; 12(6):467-71. DOI: 10.1007/BF02806027. View

2.
Fairbanks G, Steck T, Wallach D . Electrophoretic analysis of the major polypeptides of the human erythrocyte membrane. Biochemistry. 1971; 10(13):2606-17. DOI: 10.1021/bi00789a030. View

3.
Bennett G, Leblond C, Haddad A . Migration of glycoprotein from the Golgi apparatus to the surface of various cell types as shown by radioautography after labelled fucose injection into rats. J Cell Biol. 1974; 60(1):258-84. PMC: 2109130. DOI: 10.1083/jcb.60.1.258. View

4.
Winterburn P, Phelps C . The significance of glycosylated proteins. Nature. 1972; 236(5343):147-51. DOI: 10.1038/236147a0. View

5.
HURLIMANN J, Lichaa M, Ozzello L . In vitro synthesis of immunoglobulins and other proteins by dysplastic and neoplastic human mammary tissues. Cancer Res. 1976; 36(4):1284-92. View