A murine cDNA encodes a pan-epithelial glycoprotein that is also expressed on plasma cells.
Using a subtractive cDNA approach, we have identified a number of genes expressed in murine plasmacytomas, but not B or pre-B lymphomas. One of these genes, 289A, expresses a 1.8-kb microsomally localized mRNA that encodes a 314-amino-acid protein containing a signal sequence and a hydrophobic transmembrane domain. Sequence comparison suggests that the predicted protein is the murine homologue of a human cell surface pan-epithelial glycoprotein known variously as EGP, GA733-2, KSA, and KS1/4, recognized by mAb HEA125, GA733, KS1/4, CO17-1A, M74, and 323/A3. The 289A mRNA is highly expressed in normal murine tissues containing epithelial cells, and at a low level in plasma cells induced by LPS stimulation of spleen B lymphocytes. It is expressed in 15 of 16 plasmacytomas, but at a much lower level, if at all, in pre-B or B lymphomas. In human B cell lines, 289A detects a 1.5-kb mRNA in the myeloma cell line 8226, but not in Burkitt's lymphoma or lymphoblastoid cell lines. Subsequent FACS analysis of human cell lines with the mAb GA733 and KS1/4 demonstrated concordant expression of the mRNA and the protein. We conclude that 289A is the murine homologue of EGP, GA733-2, KSA, and KS1/4 Ag. Although its expression was previously thought to be restricted to epithelial cells, it is also expressed in plasma cells and is a B lymphocyte differentiation Ag. Because of the multiplicity of names, we propose calling the human gene hEGP314, and the murine gene mEGP314.
Bergsagel
P L
PL
Navy Medical Oncology Branch, National Cancer Institute, Bethesda, MD 20889-5105.
Victor-Kobrin
C
C
Timblin
C R
CR
Trepel
J
J
Kuehl
W M
WM
D000595:Amino Acid Sequence; D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics*; D000954:Antigens, Surface / Q000032:analysis*; D001483:Base Sequence; D015815:Cell Adhesion Molecules; D004247:DNA / Q000302:isolation & purification*; D000071858:Epithelial Cell Adhesion Molecule; D005260:Female; D006801:Humans; D008223:Lymphoma / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009101:Multiple Myeloma / Q000378:metabolism; D010950:Plasma Cells / Q000737:chemistry*; D012333:RNA, Messenger / Q000032:analysis; D014407:Tumor Cells, Cultured
D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D015815:Cell Adhesion Molecules; D000071858:Epithelial Cell Adhesion Molecule; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D004247:DNA