Expression of neurophysin-related precursor in cell membranes of a small-cell lung carcinoma.
A monoclonal antibody (mAb L6) to a small-cell lung carcinoma surface antigen recognizes a common epitope of vasopressin-neurophysin and oxytocin-neurophysin in hypothalamic nuclei. We now report on the identification of a neurophysin-like precursor in human lung carcinoma (LX-1) cell membrane. mAb L6 immunoaffinity chromatography of solubilized membranes resulted in a single band of approximately 45 kDa. Western blot analysis demonstrated immunoreactivity of this band with mAb L6, anti-vasopressin, and an antibody to the vasopressin precursor, pro-pressophysin. N-terminal sequencing of this band demonstrated a 21-amino acid homology with the N terminus of human pro-pressophysin, and substitution of a Cys33 residue in the tumor antigen with Arg33. Absence of immunoreactivity with the antibodies described above in cytosolic extracts and culture medium suggests nonsecretion of processed or intact pro-pressophysin-like peptide. Northern analysis of LX-1 mRNA with a 30-mer to the C terminus of rat pro-pressophysin resulted in a band of approximately 1000 base pairs, 250 base pairs larger than hypothalamic message. In situ hybridization of LX-1 tumor-bearing nude rat brain with the same probe demonstrated specific hybridization in rat hypothalamus and xenografted tumor. These findings suggest expression of a pro-pressophysin-like protein in this tumor cell line that is preferentially targeted to the cell membrane.
Rosenbaum
L C
LC
Department of Neurology, Oregon Health Sciences University, Portland.
Neuwelt
E A
EA
Van Tol
H H
HH
Loh
Y P
YP
Verbalis
J G
JG
Hellström
I
I
Hellström
K E
KE
Nilaver
G
G
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D015152:Blotting, Northern; D018288:Carcinoma, Small Cell / Q000276:immunology*; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology; D002846:Chromatography, Affinity; D000939:Epitopes / Q000032:analysis*; D006801:Humans; D008175:Lung Neoplasms / Q000276:immunology*; D008969:Molecular Sequence Data; D009481:Neurophysins / Q000235:genetics / Q000276:immunology*; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D012689:Sequence Homology, Nucleic Acid
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D000939:Epitopes; C066726:LX-1 antigen; D009481:Neurophysins; D012333:RNA, Messenger; D012334:RNA, Neoplasm