Identification of Neurophysin Immunoreactivity in Hypothalamus by a Monoclonal Antibody to a Carcinoma Cell Surface Antigen

Nilaver, Gajanan; Rosenbaum, Lawrence C.; Hellström, Karl Erik; Hellström, Ingegerd; Neuwelt, Edward A.

doi:10.1159/000125392

Cited by 12 publications

(9 citation statements)

References 14 publications

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“…Second, the L6 antigen appears to be complexed with other cell surface proteins, further complicating'efforts to identify and purify it. These technical difficulties have resulted in inconclusive and, at times, contradictory characterizations of the L6 antigen (4,10,11). However, the potential importance of the L6 antigen as a target for cancer therapy (7,8) compelled us to continue our efforts to isolate and characterize it.…”

Section: Discussionmentioning

confidence: 99%

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Cloning and expression of the tumor-associated antigen L6.

Marken

Schieven

Hellström

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

123

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The L6 cell surface antigen, which is highly expressed on lung, breast, colon, and ovarian carcinomas, has attracted attention as a therapeutic target for murine monoclonal antibodies and their humanized counterparts. Its molecular nature has, however, remained elusive. Here we describe the expression cloning of a cDNA encoding the L6 antigen. COS cells transfected with this cDNA direct the expression of an -24-kDa surface protein that reacts with the two anti-L6 monoclonal antibodies available. The predicted L6 peptide sequence is 202 amino acids long and contains three predicted NH2-terminal hydrophobic transmembrane regions, which are followed by a hydrophilic region containing two potential N-linked glycosylation sites and a COOH-terminal hydrophobic transmembrane region. The L6 antigen is related to a number of cell surface proteins with similar predicted membrane topology that have been implicated in cell growth.

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Section: Discussionmentioning

confidence: 99%

“…Although a clinical potential of the L6 mAb has been established, identification of the cell surface antigen recognized by it has been elusive, with previous reports describing it as either a glycolipid (4) or proneurophysin (10,11). Here we report that by using expression cloning technology, a cDNA clone encoding the L6 antigen was isolated.…”

mentioning

confidence: 93%

Cloning and expression of the tumor-associated antigen L6.

Marken

Schieven

Hellström

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

123

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“…Since the protein loaded in lane 2 was 100 times more than that in lane 1, it appears the antigen is found predominantly in the cell membrane. The culture medium was negative for immunoreactivity with anti-VP, anti-NP, YL-3, and mAb L6 by immunoblotting, and the serum from tumor-bearing nude rats showed no increase in VP levels by radioimmunoassay when compared to controls (6 homology with the N terminus of human PPYsin (see Table 1). A deviation between the two sequences is the substitution …”

Section: Resultsmentioning

confidence: 99%

“…Lung carcinoma cell line LX-1, established from a human small-cell carcinoma (7), was grown in spinner flasks and intracerebrally inoculated in the right cerebral hemisphere of nude rats as described (14). In addition to NP-related immunoreactivity (6) (15) and centrifuged, and the supernatants were electrophoresed.…”

Section: Methodsmentioning

confidence: 99%

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Expression of neurophysin-related precursor in cell membranes of a small-cell lung carcinoma.

Rosenbaum

Neuwelt

Tol

et al. 1990

Proc. Natl. Acad. Sci. U.S.A.

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A monoclonal antibody (mAb L6) to a smallcell 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 immunoaffmity chromatography of solubilized membranes resulted in a single band of =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 =4000 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.Lung carcinomas are well known for their association with paraneoplastic syndromes, often through production and secretion of peptide hormones. Hormones such as vasopressin (VP) (1), neurophysin (NP) (2), and bombesin (3) can stimulate growth of tumor cells by functioning as autocrine growth factors. Elevated plasma levels of tumor-secreted hormones have been documented in patients with small-cell lung carcinomas and thus may allow early detection of tumor and monitor efficacy of treatment (4).We have been characterizing a monoclonal antibody generated against a human lung adenocarcinoma (mAb L6) that binds to a surface epitope of human lung, colon, breast, and ovarian carcinomas (5). Our studies demonstrated that mAb L6 specifically recognizes a common domain within vasopressin-neurophysin (VP-NP) and oxytocin-neurophysin (OT-NP) (6). Since mAb L6 is immunoreactive with a membrane-bound protein, it was of interest to determine whether the mAb L6-reactive surface antigen was NP or NP related.We now report on the identification of a NP-like precursor isolated from the human lung cancer cell line, LX-1 (7). This tumor cell line does not appear to process or secrete this precursor, being targeted instead to the cell membrane. To our knowledge no one else has reported a neuroendocrine hormone precursor being preferentially expressed in cell membranes. Antibodies. mAb L6 is an IgG2. mAb that recognizes a cell-surface antigen in human lung, breast, colon, and ovarian carcinomas (5) as well as specifically recognizing a common domain of both VP-NP and OT-NP (6). P1.17, an IgG2a mAb, was used as a control in the blotting experiments. Y...

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Syndrome of inappropriate secretion of antidiuretic hormone in a patient with carcinoma of the nasopharynx

Kavanagh¹,

Halperin²,

Rosenbaum³

et al. 1992

Cancer

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A patient with a primary undifferentiated carcinoma of the nasopharynx manifested the clinical syndrome of inappropriate antidiuretic hormone secretion (SIADH). Immunohistochemical techniques demonstrated the presence of vasopressin, neurophysin, and their precursor (propressophysin) in the cancer cells. In situ hybridization additionally confirmed the expression of propressophysin messenger RNA in these cells. To the knowledge of the authors, this represents not only the first case of SIADH caused by carcinoma of the nasopharynx, but also the first report of pathologic confirmation of the syndrome with the use of both molecular and immunologic probes. Cancer 1992; 69:1315‐1319.

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Identification of Neurophysin Immunoreactivity in Hypothalamus by a Monoclonal Antibody to a Carcinoma Cell Surface Antigen

Cited by 12 publications

References 14 publications

Cloning and expression of the tumor-associated antigen L6.

Cloning and expression of the tumor-associated antigen L6.

Expression of neurophysin-related precursor in cell membranes of a small-cell lung carcinoma.

Syndrome of inappropriate secretion of antidiuretic hormone in a patient with carcinoma of the nasopharynx

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