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At least 199 records · Page 11Linked to original sources
PubMed1980

Elevated titers of the beta subunit of human chorionic gonadotropin in oophorectomized women being treated for trophoblastic disease.

Radioimmunoassay has shown a cross-reaction of the beta subunit of human chorionic gonadotropin (HCG) with high levels of luteinizing hormone (LH) in the serum of four women who underwent bilateral oophorectomy as part of their treatment for trophoblastic disease. Administration of oral contraceptives led to suppression of the LH and beta subunit HCG titers.

Adult↗
PubMed1998

Identification of novel transmembrane gene sequence and its use for cell-surface targeting of beta subunit of human chorionic gonadotropin.

We identified a 685-nucleotide gene fragment that codes for the transmembrane and cytoplasmic domains of glycoprotein of the LEP strain rabies virus and carried out experiments designed to express a novel fusion protein on the cell surface. The cDNA encoding the membrane anchor sequence was fused in the correct reading frame to the 3' end of the cDNA encoding the beta subunit of human chorionic gonadotropin (beta(h)CG), a secretory glycoprotein that is used as an antigen for a contraceptive vaccine being developed in our laboratory. The fusion gene cassette was placed under the control of a vaccinia virus early promoter and cloned in a host-restricted fowlpox viral vector. The recombinants, when used to infect mammalian cells that do not allow the replication of fowlpox virus, expressed the N-terminal 135 amino acid residues of beta(h)CG anchored in the cell membrane by the 75-amino acid C-terminal sequence derived from rabies virus glycoprotein. This hybrid protein is correctly processed post-translationally and transported efficiently to the plasma membrane of non-permissive cells such that the anchored beta(h)CG molecule retains the correctly folded native antigenic epitope(s).

Amino Acid Sequence↗
PubMed1996

Production of the beta-subunit of human chorionic gonadotropin in Escherichia coli and its export mediated by the heat-labile enterotoxin chain-B signal sequence.

The PCR-amplified beta-subunit of the human chorionic gonadotropin structural gene (betahCG) was cloned under the control of the tac promoter and the heat-labile enterotoxin chain B (LTB) signal sequence (LTBss). BetahCG was successfully produced, processed and exported to the periplasmic space in Escherichia coli. Expression of betahCG was confirmed by immunoblot analysis using an anti-betahCG polyclonal antibody. The processing of the protein was very efficient, as only the processed band could be detected at all time points during the course of induction. Expression was evident soon after the addition of the lactose analogue, IPTG. These results demonstrate that E. coli cells can synthesize, process and export betahCG using the LTBss.

Bacterial Toxins↗
PubMed1981

Demonstration of plasma human chorionic gonadotropin beta-subunit during pregnancy using LH-hCG receptors from immature porcine testis.

In an attempt to provide better assessment of human chorionic gonadotropin beta-subunit (hCG-beta) secretion in pregnant women, a method was developed for complete removal of hCG by porcine-purified receptors before measurement of the free hCG-beta subunit by radioimmunoassay. Blood samples of 111 pregnant women were collected and the following results were obtained: (1) Extensive removal (over 96%) of hCG allows quantitative determination of the free hCG-beta subunit by a specific radioimmunoassay. Our data demonstrate the presence of circulating hCG-beta subunit during pregnancy, a fact that was still under controversy until now. (2) In contrast with the hCG profile drug during pregnancy the free hCG-beta subunit exhibits a plasma concentration peak (400 +/- 132 ng/ml; mean +/- 1 SD) at the 12th-13th week, indicating that the changes in plasma levels of intact hCG and free hCG-beta subunit are unrelated.

Animals↗
PubMed1980

Observations on the antigenicity and clinical effects of a candidate antipregnancy vaccine: beta-subunit of human chorionic gonadotropin linked to tetanus toxoid.

Observations on the antibody response and clinical effects of injection of purified beta-subunit of human chorionic gonadotropin covalently linked to tetanous toxoid were made in 15 healthy young women who had previously undergone tubal ligation. Antibodies detectable by radioimmunoassay were found in 14 of the women. Clinical surveillance and immunologic, hematologic, and biochemical tests indicated excellent local and systemic tolerance to the antigen. No significant adverse effects on menstrual function, endocrine status, or health were found.

Antibody Formation↗
PubMed1996

Translational fusion of heat labile enterotoxin chain B and beta-subunit of human chorionic gonadotropin: periplasmic expression in Escherichia coli and its immunogenicity.

A fusion gene was constructed consisting of heat labile enterotoxin chain B (LTB) of E. coli genetically linked at its C-terminus to the beta-subunit of human chorionic gonadotropin in translational fusion, under the control of tac promoter and LTB signal sequence. Expression of the fusion gene (about 5 microgram/ml) in E. coli was confirmed by immunoblot analysis using both anti-LTB and anti-betahCG polyclonal antibodies. The fusion protein was efficiently processed and exported to the periplasmic space. LTB in the fusion protein retained its ability to bind to GM1 ganglioside receptor. Mice immunized with the fusion protein produce antibodies that recognize recombinant betahCG and the native hCG suggesting its potential use as a contraceptive vaccine.

Animals↗
PubMed1986

Elevated concentrations of the beta-subunit of human chorionic gonadotropin and testosterone in the amniotic fluid of gestations of diabetic mothers.

Hyperplasia of testicular Leydig cells and ovarian theca-lutein cells is a common histologic finding in infants of diabetic mothers. The functional correlates of this histologic finding were investigated by measurement of the beta-subunit of human chorionic gonadotropin, testosterone, dihydrotestosterone, androstenedione, estradiol, and estrone in the amniotic fluid compartment of gestations with male and female fetuses in diabetic mothers (N = 34) and control women (N = 34) at term. When compared with those of control subjects, gestations of diabetic mothers had significantly higher amniotic fluid concentrations of the beta-subunit of human chorionic gonadotropin. Gestations with either male or female fetuses in diabetic mothers had significantly higher amniotic fluid testosterone and dihydrotestosterone levels when compared with those of their respective gender controls. In gestations with male fetuses in diabetic mothers there was a significant positive correlation between the beta-subunit of human chorionic gonadotropin and testosterone. There was no significant difference in amniotic fluid androstenedione, estradiol, or estrone levels between the gestations of diabetic mothers and those of control women. These results suggest that the testicular Leydig cell and ovarian theca-lutein cell hyperplasia seen in infants of diabetic mothers is due, in part, to elevated levels of human chorionic gonadotropin and is associated with elevated testosterone and dihydrotestosterone concentrations in the amniotic fluid.

Amniotic Fluid↗
PubMed1983

Newly established uterine cervical cancer cell line (SKG-III) with Regan isoenzyme, human chorionic gonadotropin beta-subunit, and pregnancy-specific beta 1-glycoprotein phenotypes.

The production of Regan isoenzyme (heat-stable, L-phenylalanine-sensitive term-placental alkaline phosphatase), human chorionic gonadotropin beta-subunit, and pregnancy-specific beta 1-glycoprotein by newly characterized human uterine cervical cancer cell lines, SKG-IIIa and SKG-IIIb, is reported. These cell lines were derived from a moderately differentiated epidermoid cancer partially mixed with epidermoid clear-cell components. At the end of the first 4 months in culture 2 sublines with different morphologies were identified. In nude mice, SKG-IIIa produce clear-cell epidermoid cancer with much glycogen, while SKG-IIIb grew as a moderately differentiated epidermoid cancer rich in tonofilaments. The presence of Regan isoenzyme was established by biochemistry, enzyme cytochemistry, immunocytochemistry, and immunoelectrophoresis. However, the copresence of small amounts of early placental alkaline phosphatase was also demonstrated. The alkaline phosphatase specific activities of SKG-IIIa cells and SKG-IIIb cells were 3.7 and 1.4 nmol per mg protein per min, respectively. The existence was proven by radioimmunoassay of human chorionic gonadotropin beta-subunit (SKG-IIIa, 5.0 mlU/mg protein; SKG-IIIb, 4.4 mlU/mg protein), pregnancy-specific beta 1-glycoprotein (SKG-IIIa, 0.7 ng/mg protein) in the culture media as a tumor cell product. The described cell lines may serve as a more representative model system for studies of regulation of oncodevelopmental genes in gynecological tumors in general and in epidermoid cervical cancer in particular.

Alkaline Phosphatase↗
PubMed1980

Synthesis of carboxyl terminal segments of beta-subunit of human chorionic gonadotropin. Application of the two-phase method.

The synthesis in solution of carboxyl terminal peptide segments of the beta-subunit of human chorionic gonadotropin is described. The protected segments include sequences 119-131, 132-137, and 138-145. The syntheses were based on a standardized liquid-liquid extraction program for routine purification of intermediates (two-phase method). Condensation of terminally deblocked segments afforded protection peptides 132-145, 126-145, 120-145, and 119-145. Protected peptides 126-145 and 120-145 were deprotected in liquid hydrogen fluoride and used in conjugated form for immunization of rabbits. Data on the specificity of the antibody response are reported.

Amino Acid Sequence↗
PubMed2001

Analysis of the human CGB/LHB gene cluster in breast tumors by real-time quantitative RT-PCR assays.

The six genes of the human chorionic gonadotropin beta subunit (CGB) and the gene of the luteinizing hormone beta subunit (LHB) are located in a cluster that spans 50 kb on chromosome 19q13.3. Only genes CGB7, B8, B5 and B3 can generate the human chorionic gonadotropin (hCG) beta molecule. The other two genes, CGB1 and B2, encode unidentified proteins. We have previously shown that malignant breast transformation is associated with the emergence of the 'trophoblastic' CGB genes (B8, B5 and B3), in addition to the CGB7 gene, which is the only CGB gene expressed in normal breast tissue. To better understand the dysregulation of the CGB/LHB gene cluster in breast cancer, we have developed real-time quantitative RT-PCR assays to analyze each subgroup of genes (the overall CGB genes, CGB1 and B2 together, and LHB alone) in 17 unilateral invasive primary breast tumor RNAs. We also analyzed the chorionic gonadotropin alpha (CGA) gene coding for the human CGA subunit. We found that the emergence of the 'trophoblastic' CGB genes in breast tumors is (i) accompanied by an increase in the total CGB mRNA steady-state level, (ii) mainly due to overexpression of genes CGB8, B5 and B3 (expression of other genes in the CGB/LHB gene cluster (CGB7, B2, B1 and LHB) changes little if at all), and (iii) not accompanied by overexpression of the CGA gene which is necessary to produce ectopic hCG heterodimeric hormone in breast tumor cells, these latter which yet expressed the LH/CG receptor. These observations suggest that it is mainly the CGB8, B5 and B3 genes which are upregulated in the 19q13.3 CGB gene cluster in breast tumors. They also point to a role (like growth factor) of the CGbeta subunit in breast tumorigenesis, via a novel pathway independent of the LH/CG receptor.

Breast↗
PubMed1980

Immunological properties of the beta-subunit of human chorionic gonadotropin. I. Effect of chemical and enzymatic modifications.

The beta-subunit of hCG (hCG beta) displays immunological cross-reactivity with human LH (hLH). A detailed study was undertaken to investigate the effect of chemical and enzymatic modifications on the immunological behavior of hCG beta, particularly on its cross-reactivity with hLH, with a view to obtaining a highly hCG-specific antigen. hCG beta was modified in both the carbohydrate and protein parts of the molecule. The carbohydrate part was modified enzymatically by sequential cleavage of monosaccharides by specific glycosidases, and the protein portion was modified chemically in the amino and carboxyl groups and in the cystinyl, tyrosyl, histidyl, and arginyl residues. These derivatives were immunologically evaluated by RIAs; their hCG beta activities were measured in the [125I]hCG beta-anti-hCG beta system, and the hLH cross-reactivity in the [125I]hLH-anti-hLH system. The present studies have led to the following conclusions. 1) The carbohydrate does not play a significant role in the immunological activity of hCG beta. 2) The antigenic determinants of hCG beta reside primarily in the polypeptide chain and are conformational rather than sequential in nature. 3) hCG beta has two types of antigenic determinants, those which are unique to hCG and those which are common to both hCG and hLH. 4) Finally, it is possible to destroy preferentially one or the other type of determinants. The controlled reduction and alkylation of hCG beta yielded derivatives which retain significant immunological activity in the hCG beta system, but have no or reduced cross-reactivity in the hLH system. These derivatives are much more specific antigens than hCG beta and, therefore, are of potential importance for the development of a specific RIA for hCG and possibly for use as contraceptive agents.

Alkylation↗
PubMed2002

Inhibition of human chorionic gonadotropin beta-subunit modulates the mitogenic effect of c-myc in human prostate cancer cells.

BACKGROUND: Amplification of the proto-oncogene c-myc has been identified as one of the most common genetic alterations in prostate cancer, thus making it an attractive therapeutic target. However, certain prostate cancer cells are unresponsive to c-Myc inhibition. The purpose of this study was to test the hypothesis that effective growth inhibition in the refractory cancer cells can be achieved by blocking c-myc along with a growth factor using a novel phosphorodiamidate morpholino antisense oligomer-based approach. Human chorionic gonadotropin, a growth factor implicated in neoplasm, causes activation of c-myc through a G-protein-coupled pathway of signal transduction. METHODS: In this study, the effect of inhibition of beta-hCG and c-myc singly or in combination was evaluated in DU145 (RB -/-, p53-/-, androgen-independent) and LNCaP (Rb+/+, p53 +/+, androgen-sensitive) human prostate cancer cell lines and in a DU145 subcutaneous xenograft murine model. RESULTS: Antisense phosphorodiamidate morpholino oligomers directed against beta-hCG and c-myc caused a specific decrease of the target protein levels. Unlike LNCaP cells, DU145 cell growth was refractory to c-Myc inhibition. Unresponsiveness to c-myc inhibition in DU145 cells was overcome by targeting both beta-hCG and c-myc genes, resulting in potentiation of the antiproliferative effect seen with inhibition of beta-hCG alone. CONCLUSIONS: The inhibition of beta-hCG sensitizes prostate cancer cells to the antiproliferative effects of c-Myc inhibition, including tumors that are refractory to c-Myc decrease alone.

Animals↗
PubMed1979

Human chorionic gonadotropin beta-subunit--like immunoreactive material in the plasma of women wearing an intrauterine progesterone contraceptive system.

A systematic study of the presence of human chorionic gonadotropin beta-subunit--like (hCG beta-like) material in the plasma of one woman sampled daily throughout one menstrual cycle and in nine women studied on a selected bleeding schedule has been carried out. Peaks of immunoreactive hCG beta-like activity were found in the follicular and luteal phases of these menstrual cycles which could not be explained by a cross-reaction of luteinizing hormone (LH) in the plasma. The same nine women were studied again 1 month after the insertion of the intrauterine progesterone contraceptive system (IPCS) and again 6 to 8 months later. Although the presence of hCG beta-like immunoactivity correlated with LH values in the cycles studied, there was a significant decrease in its presence 1 month after IPCS use and a highly significant decrease after 6 to 8 months of use.

Chorionic Gonadotropin↗
PubMed1996

Structural analysis of the carboxyl terminal peptide from human chorionic gonadotropin beta-subunit by two-dimensional nuclear magnetic resonance spectroscopy.

PROBLEM: Vaccines that target human chorionic gonadotropin (hCG) might be made more effective through greater understanding of the solution three-dimensional structure and behavior of the hormone. METHOD: A 37-amino acid carboxyl terminal peptide of the hCG beta subunit was synthesized, purified, and analyzed by two-dimensional nuclear magnetic resonance spectroscopy. RESULTS: Double-quantum filtered correlated spectroscopy data on the peptide in water at 4 degrees C reveals 27 multiplets in the peptide fingerprint region, as expected. A nuclear Overhauser effect spectroscopy spectrum shows several intraresidual peaks in the amide region but lacks clearly assignable interresidual signals. CONCLUSION: By itself in water the carboxyl terminal peptide of hCG lacks defined secondary structure elements and is thus likely a random coil. The presence of beta turns appears possible although neither their existence nor their localization can be confirmed.

Amino Acid Sequence↗
PubMed2003

Human chorionic gonadotropin free beta-subunit in the human seminal plasma: a new marker for spermatogenesis?

UNLABELLED: In the past 20 years, several factors were detected in the human seminal plasma and proposed as markers for spermatogenesis. Human chorionic gonadotropin (hCG) and its beta-subunit were therefore investigated, and their seminal levels were found to be higher than those detected in the serum and to correlate with sperm parameters. OBJECTIVE: We designed a retrospective study to determine the suitability of hCG free beta-subunit concentration in the seminal plasma of fertile and infertile male patients as marker of spermatogenesis. STUDY DESIGN: A total of 79 infertile male patients were divided into four groups by their semen analysis results (group 1 [n=8]: azoospermia; group 2 [n=21]: severe oligozoospermia; group 3 [n=40]: oligoasthenospermia (OAS); group 4 [n=10]: asthenospermia) and 10 healthy volunteers of proven fertility were evaluated. RESULTS: The hCG free beta-subunit levels in the seminal plasma were found to be significantly higher (P<0.0001) in the control group in respect to those assayed in the infertile patients and showed a correlation with sperm count (r=0.5) and total motile sperm density (r=0.5). Twenty-five patients were on treatment with oral Mesterolone (100mg daily) plus Tamoxifen (20mg daily) for 3-6 months. Apart from a significant improvement (P<0.05) in sperm morphology, no significant changes in sperm count and motility were observed after the treatment in all the patients. In the seminal plasma of 10 patients who showed a significant increase in sperm count, hCG free beta-subunit levels were found to be significantly higher compared to those detected in the remaining patients (P<0.01). In all patients, these levels remained unchanged after the treatment. CONCLUSIONS: The evidence regarding the positive correlation between hCG free beta-subunit levels in the seminal plasma and sperm concentration is consistent with the previous results regarding hCG levels. A previous study demonstrated that testosterone levels in seminal plasma correlated with sperm concentrations; from the same evidence regarding hCG we hypothesize that seminal plasma testosterone and hCG levels are correlated. Thus, hCG may play a paracrine role in the intratesticular regulation of testosterone secretion.

Adult↗
PubMed1990

N-linked oligosaccharides on free alpha interfere with its ability to combine with human chorionic gonadotropin-beta subunit.

The purpose of the study was to examine the role of N-linked oligosaccharides in preventing combination of free alpha molecules with human chorionic gonadotropin (hCG)-beta subunit to form the intact hormone, hCG. Culture media from JEG cells incubated in the presence or absence of Swainsonine were filtered on Sephadex G-100, and free alpha was identified by radioimmunoassay. Swainsonine interferes with glycosylation by inhibiting alpha-mannosidase II, resulting in formation of hybrid structures. Approximately 50% of the free alpha molecules from Swainsonine-treated cells (Swainsonine pool 2) had an apparent molecular size that was smaller than that of free alpha from control cells. The oligosaccharides of control alpha molecules were resistant to endo-beta-N-acetylglucosaminidase H treatment. In contrast, virtually all of the Swainsonine free alpha molecules contained endo-beta-N-acetylglucosaminidase H-sensitive oligosaccharides. Swainsonine free alpha and control free alpha molecules were incubated with an excess of hCG-beta subunit, followed by chromatography on Sephadex G-100. Each fraction was assayed by radioimmunoassay for intact hCG and for alpha. Less than 10% of control free alpha molecules combined with hCG-beta. In contrast, 54% of Swainsonine alpha pool 2 and 40% of Swainsonine alpha pool 1 combined with beta to form hCG. Thus, modulation of N-linked oligosaccharide processing converted free alpha molecules to forms that can combine with hCG-beta. These results indicate that the inability of a substantial portion of control free alpha molecules to combine with hCG-beta is due to the presence of N-linked oligosaccharide structures that interfere with combination.

Alkaloids↗
PubMed1989

Site-directed mutagenesis of the human chorionic gonadotropin beta-subunit: bioactivity of a heterologous hormone, bovine alpha-human des-(122-145)beta.

Human CG contains an alpha-subunit, common to the pituitary glycoprotein hormones, and a hormone-specific beta-subunit, but unlike the pituitary beta-subunits, hCG beta is characterized by an O-glycosylated carboxy-terminal extension. A mutant beta-subunit, des-(122-145)hCG beta, was prepared using site-directed mutagenesis, and the pRSV expression plasmids were transfected into Chinese hamster ovary cells that produce the bovine alpha-subunit (b alpha). The mutant beta-subunit binds to b alpha, and the heterologous gonadotropin, b alpha-des-(122-145)hCG beta, was capable of stimulating steroidogenesis in cultured Leydig tumor cells (MA-10) to the same extent as standard hCG. When compared with the heterologous gonadotropin, b alpha-hCG beta wild type, the hybrid hormone with the truncated hCG beta exhibited equal potency, within the accuracy of the RIAs used to determine hormone concentrations, and gave a similar time course of steroidogenesis. Interestingly, these transformed Leydig cells do not distinguish between the steroidogenic potencies (as measured by progesterone production) of hCG and human LH (hLH) as do some preparations of normal rodent Leydig cells (as measured by testosterone production). However, the MA-10 cells were able to distinguish hCG from hLH based on their cAMP response; the latter produced a greater response at both maximal and submaximal gonadotropin concentrations. The two expressed heterologous gonadotropins were equipotent in their abilities to stimulate cAMP and gave similar time courses of cAMP accumulation in MA-10 cells. Thus, the carboxy-terminal extension of hCG beta is not required for association with the alpha-subunit nor for functional receptor binding, as judged by cAMP accumulation and progesterone production in MA-10 cells.

Animals↗