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PubMed1993

A receptor binding site identified in the region 81-95 of the beta-subunit of human luteinizing hormone (LH) and chorionic gonadotropin (hCG).

Two series of overlapping peptides comprising the entire sequences of the beta-subunits of human lutropin (LH) and choriogonadotropin (hCG) were prepared by a comprehensive synthetic strategy in order to identify all linear regions of the subunit that may participate in binding of the hormone to its receptor. Each series of peptides (15 residues in length) spanned the entire amino acid sequences of the two beta-subunits. The peptides were tested for their ability to inhibit the binding of 125I-labeled hCG or LH to rat ovarian membranes and for their ability to inhibit hCG-stimulated progesterone production in a Leydig cell bioassay. The most potent inhibitor of LH/hCG binding was a peptide containing the sequence beta 81-95, a receptor binding site of the LH/hCG beta subunit not previously described. The concentration at which LH/hCG binding was inhibited at 50% (IC50) was 20 microM and 30 microM for hCGbeta 81-95 and LH beta 81-95, respectively. These peptides also inhibited the stimulation of progesterone production by hCG in Leydig cell bioassays. In order to determine important residues that inhibit binding within this region, a third set of peptides was synthesized in which each residue of hCG beta 81-95 was sequentially replaced with the residue L-alanine. Five residues (Leu-86, Cys-88, Cys-90, Arg-94, and Arg-95) were critical for maximal inhibition of hCG binding by CG beta 81-95. In addition to site beta 81-95, other sites that inhibited hCG/LH binding but with significantly lower potencies included hCG beta 1-15, LH beta 41-55, and LH beta 91-105.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed2004

Breast carcinoma with choriocarcinomatous features.

Although breast carcinomas have been shown to produce various ectopic substances, including human chorionic gonadotropin, it is rare to identify morphologic differentiation compatible with the hormone produced by a tumor. Presently, only eight cases of breast carcinoma with focal choriocarcinomatous differentiation have been reported in the literature. This article describes the pathologic findings, immunohistochemical profile, and clinical course in two additional cases of this unusual variant of breast carcinoma. In the first case, the tumor had morphologic features suggestive of medullary carcinoma, and the patient is doing well 12 months after presentation. In the second case, the tumor was locally advanced at presentation with histologic features consistent with metaplastic carcinoma having squamous, sarcomatoid, and choriocarcinomatous elements. The patient presented with extensive multifocal metastases 6 months after the initial presentation and is not responding well to standard or experimental treatment regimen. Immunostaining for the beta subunit of human chorionic gonadotropin was localized mostly, but not entirely, to multinucleated syncytiotrophoblast-like giant cells within both tumors.

Adult↗
PubMed1989

Chorionic gonadotropin synthesis by human tumor cell lines: examination of subunit accumulation, steady-state levels of mRNA, and gene structure.

A number of tumor cell lines have been examined that differentially produce human chorionic gonadotropin and the isolated alpha- or beta-subunits. It has been demonstrated that all of the cell lines studied to date contain genes for both alpha- and beta-subunits, indicating that differential and exclusive expression of one subunit is not the result of a particular cell line having lost the gene for the alternate subunit as a consequence of chromosome changes accompanying cell transformation. Because many of these established cell lines are aneuploid, it is also significant that no evidence was found for gene amplification in cell lines producing alpha-subunit at very high levels compared to those with very low level expression. Analysis of restriction endonuclease digests of tumor cell DNAs has demonstrated identical patterns for beta-subunit in KpnI digests and KpnI/HindIII double digests. Polymorphisms were observed for alpha-subunit in EcoRI and HindIII digests, but these did not correspond with expression of the alpha-subunit. Significant levels of either mRNA (as determined by dot blot and Northern transfer hybridization analysis) were accompanied by corresponding elevated levels of alpha- and beta-subunits (as determined by radioimmunoassay), suggesting that regulation of subunit production most likely occurs at a pretranslational stage. However, there were apparent differences in the relative ratio of alpha- and beta-subunits and their cognate mRNAs among the cell lines.

Chorionic Gonadotropin↗
PubMed1983

Determination of gestational age by serum concentrations of human chorionic gonadotropin.

To examine the accuracy and predictability of human chorionic gonadotropin concentrations in determining gestational age, serum concentrations of human chorionic gonadotropin (beta-subunit) were measured during the first 157 days after last menses. Using the regression curve generated, human chorionic gonadotropin concentrations obtained during the first 60 days accurately predicted the day of gestation. The difference (mean +/- SD) between the human chorionic gonadotropin-predicted estimated date of confinement and the estimated date of confinement established by known dates of last menses was 3.1 +/- 2.3 days. In patients followed to parturition, the difference between human chorionic gonadotropin-estimated gestational age and gestational age by physical assessment of the neonate was 8.1 +/- 7.1 days. After 60 days' gestation, human chorionic gonadotropin concentrations vary widely and are of little value in predicting gestational age. In addition to documenting conception, early human chorionic gonadotropin determinations accurately date the gestation and complement other clinical and biophysical methods for determining gestational age that are frequently used later in pregnancy.

Chorionic Gonadotropin↗
PubMed1990

[Development of highly sensitive enzyme immunoassay to measure urinary beta-core fragment in patients with gynecological cancer].

In addition to human chorionic gonadotropin (hCG) and its free subunits, low molecular weight hCG beta-related fragments have been previously demonstrated in pregnancy urine and in the urine of patients with trophoblastic and nontrophoblastic tumors. The urinary beta-core fragment in particular is focused on as a new tumor marker in gynecological malignancies. We developed an EIA for the beta-core fragment using the monoclonal antibody (MoAb229) which specifically recognized the core portion of hCG beta. By measuring with MoAb229-EIA, it was clearly revealed that urine obtained from normal pregnant women as well as from patients with choriocarcinoma and nontrophoblastic ovarian cancer contains a large amount of the beta-core fragment when separated on Sephadex G-100. We conclude that our MoAb229-EIA is a useful tool to use in detecting the beta-core fragment, a new tumor marker, in the urine of gynecological cancer patients.

Antibodies, Monoclonal↗
PubMed1983

Sodium butyrate produces concordant expression of "early placental" alkaline phosphatase, pregnancy-specific beta 1-glycoprotein and human chronic gonadotropin beta-subunit in a newly established uterine cervical cancer cell line (SKG-IIIa).

The production of early and term placental alkaline phosphatase (ALP), human chorionic gonadotropin beta-subunit (beta-hCG) and pregnancy-specific beta 1-glycoprotein (SP1) was confirmed in the newly established uterine cervical cancer call line SKG-IIIa. Treatment of these cells in culture with sodium butyrate caused an increase of all of these oncodevelopmental proteins. On the other hand, prednisolone treatment enhanced only term placental ALP, while it reduced early placental ALP, beta-hCG and SP1. These data suggested that such oncotrophoblastic proteins as early placental ALP, beta-hCG and SP1 were concordantly modulated by butyrate and prednisolone. These findings may support the possibility of the reexpression of sets of development phase-specific genes in cancer cells.

Alkaline Phosphatase↗
PubMed1982

Specific enzyme immunoassay for human chorionic gonadotropin using antibody to the synthetic peptide corresponding to the carboxyl-terminal region of the beta-subunit of hCG.

A sandwich-type enzyme immunoassay for human chorionic gonadotropin (hCG) was developed with anti hCG-beta antibody-enzyme complex and the immobilized solid-phase antibody which was prepared from the antiserum to the synthetic peptide corresponding to the carboxyl-terminal region of the beta-subunit of hCG (hCG-beta). This assay system showed a high sensitivity equal to the radioimmunoassay and did not cross-react with human luteinizing hormone (hLH), human follicle stimulating hormone (hFSH) or alpha-subunit of hCG (hCG-alpha). The coefficients of variation in within-run and between-run were less than 10% and there was a good correlation between the enzyme immunoassay and the radioimmunoassay of serum sample with a regression equation of y = 1.038 x -0.647 and a correlation coefficient of r = 0.953.

Chemical Phenomena↗
PubMed1993

Monoclonal antibodies to human chorionic gonadotropin (HCG) and their use in two-site binding enzyme immunoassays.

A panel of mouse monoclonal antibodies (MABs) was produced against human chorionic gonadotropin (HCG) and its isolated beta-subunit (beta-HCG). According to their binding specificities the antibodies could be divided into HCG-specific and cross-reactive MABs. The HCG-specific antibodies reacted with antigenic sites on holo-HCG or holo-HCG and beta-HCG, or exclusively with the non-associated beta-HCG chain. The cross-reactive antibodies reacted with either HCG and luteinizing hormone (LH) or with HCG, LH, follicle-stimulating hormone (FSH) and thyroid-stimulating hormone (TSH). According to the binding specificities of the MABs and their reciprocal inhibition detected in two-site binding enzyme immunoassays (EIA), altogether 13 epitopes (including the 3 hidden epitopes detectable only on free non-associated beta-HCG) were distinguished by the antibodies described here. Antibody combinations resulting in most effective and specific HCG- or beta-HCG-determination were used as clinical assays and proved their reliability and correctness for monitoring patients with HCG- and/or beta-HCG-producing tumors before and after therapy.

Animals↗
PubMed1989

Blastocyst implantation precedes induction of insulin-like growth factor II gene expression in human trophoblasts.

The cytotrophoblast cell population of the human embryonic conceptus proliferates rapidly during the first month following blastocyst implantation. Since the trophectoderm lineage is established in preimplantation morula/blastocysts, the scenario underlying initiation and maintenance of the rapid proliferative phenotype of cytotrophoblasts is a central issue. The insulin-like growth factor II (IGF-II) gene is highly expressed in proliferative cytotrophoblasts of first trimester placenta and performs as a placenta growth factor. To establish a temporal correlation between IGF-II expression and initiation of highly proliferative trophoblasts in human development, we employed in situ hybridization analysis of the expression of the IGF-II and human chorionic gonadotropin beta-subunit (beta-HCG) genes in human pre- and postimplantation development. The data show that the appearance of high steady-state levels of IGF-II transcripts in trophoblasts is a postimplantation event, whereas beta-HCG transcripts can already be detected in preimplantation development. This observation makes a role for endogenously produced IGF-II in the normal development of preimplantation embryos unlikely, but suggests that endogenously produced IGF-II participates in the formation and subsequent expansion of the rapid proliferative phenotype of the trophoblastic shell, following implantation.

Blastocyst↗
PubMed1990

[Monoclonal antibodies to non-assembled alpha and beta chain of human chorionic gonadotropin (hCG)].

Using a panel of monoclonal antibodies (MCA) to human chorionic gonadotropin (hCG) and its alpha and beta subunits and additional MCA to the non-assembled, free alpha and beta chains which were produced in the course of the present experiments, it was possible to extend the previously established epitope map of hCG. Two MCAs turned out to be specific for the free alpha chain of the glycoprotein hormones (GPH) and, thus, did not react with holo hCG. Two other MCA recognized two epitopes (beta 6 and beta 7) on the free form of the hCG beta only. Again, no holo hormone cross-reaction was observed. Whereas previously only nine antigenic hCG determinants (3 alpha, 4 beta, 2c) had been demonstrated, it was now possible to distinguish fourteen epitopes (5 alpha, 5 beta, 4c). In addition, epitope maps were established for the non-assembled, free subunits of hCG. These comprise six epitopes on the alpha chain (alpha 1- alpha 6) and seven on the beta chain (beta 1- beta 7). Both so far generally accepted premises of Judith Vaitukaitis, claiming the beta chain of the GPH to be immunologically species-specific, the beta chain to be immunologically hormone-specific, were clearly disproven by demonstrating inter- and intra-species cross-reaction of some MCA. Based on the immunological topography of the holo hCG molecule and its free subunits, highly specific and sensitive immuno-enzymometric assays (IEMA) with predictable specificities were designed, measuring either non-assembled subunits alone or in combination with the intact hormones.

Antibodies, Monoclonal↗
PubMed1986

[Human chorionic gonadotropin-like substance (hCGLS) in male patients with gastrointestinal cancer].

Human chorionic gonadotropin-like substance and beta-subunit hCG were measured by a double antibody radioimmunoassay in blood and cancer tissue from male patients with gastrointestinal cancer Elevated serum hCGLS levels were observed in 6/8 (75%) of male patients with early gastric cancer, 14/22 (63.7%) with resectable, 4/10 (40%) with unresectable gastric cancer and 10/13 (76.7%) with resectable colorectal cancer. In benign diseases none had an elevated level in serum hCGLS. Serum hCGLS levels showed a declining tendency with progress of disease as well as with low histologic differentiation. HCGLS levels in gastric and colorectal cancer tissues were significantly higher than those in normal mucosal tissue. There were no correlation between hCGLS and beta-subunit hCGLS tissue levels and tumor size was observed in colorectal cancer, while not in gastric cancer. Thus, hCGLS may be of practical value in complementary diagnosis of male gastrointestinal cancer.

Adult↗
PubMed1993

Differential secretion and glycosylation of recombinant human chorionic gonadotropin (beta hCG) synthesized using different promoters in the baculovirus expression vector system.

Recombinant baculoviruses vAc beta hCGCOR and vAc beta hCGPOL, carrying the gene (beta hCG) encoding the beta-subunit of human chorionic gonadotropin under the transcriptional control of the late AcNPV core protein gene promoter (PCOR) and the very late polyhedrin gene promoter (PPOL), respectively, were constructed and used to infect lepidopteran cells. Western blot analysis of intra- and extracellular recombinant beta hCG (re-beta hCG) revealed that the secretion of beta hCGCOR was relatively higher. Enzymatic and chemical analysis of carbohydrates showed that beta hCGCOR was more glycosylated than beta hCGPOL. However, the insect-derived beta hCG, with a high-mannose type of sugar, was glycosylated differently and to a lesser extent when compared with the native, urinary beta hCG, and consequently, beta hCGCOR was more bioactive on a unit-mass basis than beta hCGPOL. This temporal gene expression strategy, besides being able to circumvent the 'secretory load' encountered during the synthesis of extensively glycosylated proteins in the baculovirus system, also offers a model to study the role of carbohydrates, both in qualitative and quantitative terms, in protein structure and function.

Animals↗
PubMed1988

An improved immunogen for anti-human chorionic gonadotropin vaccine eliciting antibodies reactive with a conformation native to the hormone without cross-reaction with human follicle stimulating hormone and human thyroid stimulating hormone.

Beta-subunit of human chorionic gonadotropin (hCG) was associated with alpha-subunit of ovine luteinizing hormone (OLH) to create a heterospecies dimer (HSD) which has a higher steroidogenic potency than the homologous dimer of alpha hCG and beta hCG in the mouse Leydig cell bioassay. The properties and merits of the antibodies induced by this HSD and beta hCG linked to carrier(s) were investigated in rodents and in a subhuman primate species. The antisera had, in both cases, high affinity for binding with hCG (K alpha = 10(9)-10(10) M-1). The mean (+/- S.E.M.) bioneutralization capacity as a percentage of immunoreactivity (determined by radioimmunoassay (RIA)) of the antibodies generated by the HSD-carrier in rats and bonnet monkeys was higher in comparison with those induced by beta hCG linked to carrier (80 +/- 2.3% vs. 63 +/- 1.5% in rats, and 65 +/- 1.9% for HSD vs. 44 +/- 3.7% in monkeys). None of the sera gave any evidence of cross-reactivity with human follicle stimulating hormone (hFSH) and human thyroid stimulating hormone (hTSH).

Animals↗
PubMed1993

A bacterial protein has homology with human chorionic gonadotropin (hCG).

Studies from our laboratory have demonstrated the presence of a 48.5 kD cell wall protein in the bacterium, Xanthomonas maltophilia, which immunologically resembles the beta subunit of human chorionic gonadotropin. Primers were designed from the amino acid sequences of enzymatically cleaved peptide fragments of this protein. These primers were used to obtain PCR amplified products, which were subsequently cloned in a PCR11TA cloning vector, and a 492 base pair nucleotide sequence was obtained with a 164 amino acid open reading frame. When this nucleotide sequence was aligned with exon 2 of genes 5 and 6 of the beta hCG gene, a 53% homology was observed. The translated protein sequence had a 35% homology with hCG and a 25% homology with human luteinizing hormone.

Amino Acid Sequence↗
PubMed1981

Elaboration of human chorionic gonadotropin by lung tumors: an immunocytochemical study.

The highly sensitive peroxidase-antiperoxidase immunocytochemical method was used to demonstrate the presence of the beta-subunit of human chorionic gonadotropin (HCG) within paraffin sections of human lung tumors of diverse histologic patterns. Of the 61 tumors studied, 51 (84%) displayed HCG-like immunoreactivity. This is a much higher incidence than was expected considering studies by other investigators in which serum samples from patients with lung cancer were assayed for HCG. Our results are, however, consistent with data from studies by other investigators in which tumor extracts were assayed for HCG. In addition, it was found that HCG production was often linked with glycogen storage within tumor cells. This may explain the association of HCG production with large-cell carcinomas of the lung, because these tumors often contain copious quantities of glycogen.

Carcinoma, Bronchogenic↗