Evidence for altered synthesis of human chorionic gonadotropin in gestational trophoblastic tumors.

Tissue extracts of molar tissue or choriocarcinoma, blood, or urine of 21 women with gestational trophoblastic disease were analyzed for hCG and its subunits. The extracts or biologic fluids were initially chromatographed through a standardized Sephadex G-100 column. Each fraction was radioimmunoassayed in homologous hCG, hCGalpha, and hCGbeta assays. Extracts of four hydatidiform moles contained primarily hCG but no free alpha subunit of that hormone. One of the molar extracts contained a small amount of free hCGbeta not observed in the small amount of free hCGbeta not observed in the extracts of the other three moles. Plasma and urine samples from 18 women with localized or metastatic gestational trophoblastic disease contained hCG but no free alpha or beta subunits; the neoplasms of those patients readily responded to chemotherapy, and all patients have had no evidence of disease for at least one year. The major portion of immunologic hCG present in the biologic samples was indistinguishable from native hCG in its physical behavior on Sephadex G-100 chromatography. On the other hand, three women with widely metastatic tumors died in spite of extensive chemotherapy. Extracts of tumors from two of those patients contained hCG and free subunits of hCG. The urine and plasma of the third patient contained hCG and hCGalpha with the concentration of hCGalpha far exceeding that for hCG in urine. The results of these studies clearly show a disparity between the forms of hCG found in the normal placenta and pregnancy sera, as previously reported, and those found in the neoplastic trophoblast with varying degrees of anaplasia. The most striking finding was the absence of free circulating hCGalpha in the sera in patients with gestational trophoblastic disease which responded to chemotherapy, since free hCGalpha is readily detectable in the sera of normally pregnant women.     

Thyrotoxicosis in a male patient associated with excess human chorionic gonadotropin production by germ cell tumor.

We report a case of a man with thyrotoxicosis due to excess production of human chorionic gonadotropin (hCG) by metastatic choriocarcinoma, followed by alterations of his thyroid function tests by nonthyroidal illness. All reported cases of thyrotoxicosis due to high hCG levels in male patients are reviewed. Patients with this syndrome usually have widespread choriocarcinoma and relatively few symptoms of thyrotoxicosis. Typically, if the patient survives the metastatic germ cell tumor, the thyrotoxicosis resolves as the hCG levels decrease after chemotherapy directed at the choriocarcinoma. Only rarely are specific antithyroid medications required. The hCG molecule directly stimulates the thyroid gland, and these patients appear to have in the serum a predominance of acidic variants of hCG with greater intrinsic thyroid-stimulating activity than the hCG secreted during a normal pregnancy. In general, these patients have a poor prognosis due to the usually widespread nature of the germ cell tumor at the time of diagnosis.     

Human chorionic gonadotropin (hCG) beta-core fragment is produced by degradation of hCG or free hCG beta in gestational trophoblastic tumors: a possible marker for early detection of persistent postmolar gestational trophoblastic disease.

The present study was undertaken to investigate whether human chorionic gonadotropin (hCG) beta-core fragment (hCG beta cf) was directly produced by gestational trophoblastic tumors. Immunoreactivity of hCG beta cf was demonstrated in the extracts as well as in the culture media of hydatidiform mole tissues. It was also present in the extracts of choriocarcinoma tissues, and its molar concentration exceeded that of intact hCG. The presence of hCG beta cf was then confirmed by gel chromatography and Western blot analysis. Immunohistochemistry showed localization of hCG beta cf immunoreactivity to the syncytiotrophoblasts and scattered cells in the stroma of mole tissue, and to syncytiotrophoblastic cells in choriocarcinoma. Immunoreactivity of hCG beta cf was also detected in the sera of the patients with gestational trophoblastic disease, although the hCG beta cf/hCG ratio was less than one hundredth of that in the tissue extracts. Serial measurement of serum hCG beta cf levels after mole evacuation showed that they declined much more rapidly than those of hCG and became undetectable in the patients with subsequent spontaneous resolution, while hCG beta cf remained or became detectable before the rise of hCG was observed in the patients with subsequent persistent trophoblastic disease. Taken together, these results suggest that hCG beta cf is directly produced by gestational trophoblastic tumors, and monitoring of hCG beta cf in the serum after mole evacuation may be useful for early prediction of subsequent development of postmolar persistent trophoblastic disease.     

Significance of radioimmunoassay of human chorionic gonadotropin and alpha fetoprotein in nonseminomatous germ cell tumors of the testis

Radioimmunoassays of human chorionic gonadotropin (HCG) and alpha fetoprotein (AFP) made in 49 patients with nonseminomatous testicular tumors have shown that these investigations make the diagnosis more precise, permit to follow up the dynamics of the course of the disease and the effectiveness of treatment and may help to reveal the presence of otherwise undetectable tumorous metastases. The significance of the these assays is enhanced if the two tumorous proteins are investigated in parallel. The results proved rightly positive in 43 (87.8%) and falsely negative in 6 (12.2%) of the patients. The absence of HCG and AFP production in some of the patients with an active disorder has not as yet been elucidated.     

Monitoring of patients with non-seminomatous germ cell tumors of the testis by determination of alpha-fetoprotein and beta-human chorionic gonadotropin levels and by computed tomography.

The results of a 7-year monitoring of 230 patients with non-seminomatous testicular tumors are reported with respect to the employment of radioimmunoanalysis of alpha-fetoprotein and beta-human chorionic gonadotropin levels and CT examinations of retroperitoneum and lungs. Prior to orchiectomy, elevated levels of at least one of these markers were found in 79% of patients. After orchiectomy, tumor marker levels were in 70.4% of patients in agreement with the results of CT examinations. After the completion of chemotherapy, in more than a half of patients normal tumor marker levels and positive CT findings were observed. These results were most often due to the presence of mature teratoma. In Stage I patients the advantages of tumor marker determinations and CT examinations in the early detection of tumor progression have fully been confirmed.     

Insulin stimulates synthesis and release of human chorionic gonadotropin by choriocarcinoma cell lines

Recent studies have shown that insulin regulates placental lactogen, progesterone, and estrogen production from human trophoblast cells. This study was performed to examine whether insulin also regulates the production of hCG by this type of cell. After 24-36 h of preincubation, JEG-3 and JAR cells (2-3 x 10(5) cells/ml.well) or human term trophoblast cells (1 x 10(6) cells/ml.well) were exposed to the test hormone in serum-free Dulbecco's Modified Eagle's Medium for 24-96 h. Secretion of hCG from JEG-3 cells was stimulated by human insulin, human proinsulin, or porcine insulin in a dose-dependent manner, with lowest effective doses of 6.7, 96, and 53 mg/L, respectively. Time-course studies showed that hCG secretion peaked at 72-96 h with insulin exposure; in contrast, no decernable peak was seen without insulin in serum-free media. Exposure of JEG-3 cells for 24 h to 209 mg/liter insulin stimulated hCG synthesis, with 40 +/- 3% more immunoreactive intracellular hCG (P less than 0.05). Cells grown in the presence of insulin and [35S]methionine had 47 +/- 21% more labeled intracellular hCG and 56 +/- 13% more immunoprecipitable [35S]methionine-hCG secreted into the medium than the control cultures (P less than 0.05). During this time period, human placental lactogen release and total trichloroacetice acid-precipitable [35S]methionine protein were not increased. The insulin-induced stimulation of hCG synthesis was inhibited by cycloheximide. Additionally, insulin did not significantly affect total intracellular protein during 24-96 h of incubation. Insulin also increased hCG release from JAR cells, but not from human term trophoblast cells. A mouse monoclonal antibody to the IGF-I receptor inhibited the stimulation of insulin in JEG-3 cells. We conclude that insulin stimulates the synthesis and secretion of hCG from JEG-3 cells and JAR cells, and that hCG regulation in choriocarcinoma cells differs from that in primary human placental trophoblast cells. The effect of insulin on JEG-3 cells may be mediated in part through the insulin-like growth factor-I receptor.     

Ectopic beta-human chorionic gonadotropin production by a human hepatoma cell line (FOCUS): isolation and immunochemical characterization

We have established a human hepatocellular carcinoma cell line designed FOCUS that produces and secretes the beta-subunit of hCG. In the study of beta hCG production by FOCUS cells, we have developed and employed a series of monoclonal immunoradiometric assays (IRMAs) that detect epitopes unique to beta hCG, alpha hCG, hCG, and sequence-specific regions of the carboxyl-terminal peptide of beta hCG. The cells secrete approximately 15 ng beta hCG/10(6) cells and per 24 h; however, we were unable to detect either hCG or the alpha-subunit. The ectopic beta hCG was subsequently affinity purified from the culture medium and partially characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. The mol wt of ectopic beta hCG was approximately 35,000 daltons. Immunochemical analysis of ectopic beta hCG by sequence-specific monoclonal antibodies revealed that epitopes corresponding to amino acid sequences 109-115, 121-145, 134-140, and 139-145 of the carboxyl-terminal peptide were present. FOCUS cells also demonstrate an intracytoplasmic localization of beta hCG by immunoperoxidase-staining techniques. Taken together, these findings suggest that FOCUS cells produce and secrete only beta hCG and that thus far, its physical properties appear indistinguishable from those of the native subunit. This unique cell line will be useful to study beta hCG gene(s) regulation as well as the mechanisms of ectopic beta hCG production and secretion.     

Detection of p53 gene mutation by using a novel biosensor based on localized surface plasmon resonance

Few studies to date have reported on the development and application of a nanobiosensor based on localized surface plasmon resonance (LSPR) for detecting gene mutations. This study aimed to develop a novel LSPR biosensor used for detecting p53 mutation. Nanosphere lithography was used to fabricate the silver nanoparticles. The DNA probe was designed to recognize the target sequence and immobilized on the chip surface by a covalent-coupling method using amine-group ligands. Synthetic oligonucleotides or PCR products were amplified from genomic DNA taken from blood samples and hybridized with the immobilized probe. Wild-type and mutant p53 was detected by measuring shifts in peak of LSPR extinction spectra. The low detection limit of the sensor for target sequence was 10 nM, and detection occurred over a wide dynamic range (10 nM - 10 μM). Importantly, the differences in measuring signal between wild-type and mismatched p53 DNA was significant, allowing for this sensor to effectively discriminate against single base mutations. In conclusion, we developed a biosensor with potential as a rapid, label-free, sensitive, and low-cost method for detecting p53 mutation. Our results suggest that such an LSPR-based biosensor provides an attractive alternative for clinical detection of genetic mutation.     

Inhibition of implantation and termination of pregnancy in the rat by a human chorionic gonadotropin antagonist

Administration of varying doses (10-50 micrograms) of deglycosylated human CG (DG-hCG) which was previously shown to be a potent hormonal antagonist in vitro, to pregnant rats inhibited implantation and terminated gestation. When administered between days 1-5 implantation was inhibited as seen on day 10. Serum progesterone levels were also suppressed. Similar doses administered between days 8 and 11 resulted in complete fetal resorption when examined on day 16. This was also accompanied by a dramatic reduction in serum progesterone. A dose of 50 micrograms DG-hCG given during the second half of pregnancy between days 13 and 16 had no deleterious effect on pregnancy including the day of parturition but the number of pups delivered was reduced by 26% as compared to 3% loss in control groups. It is concluded that DG-hCG can successfully antagonize hormone action in vivo by blockade of ovarian receptor sites for LH in the pregnant rat.     

Comparison of the biological and immunological properties of glycosylation deficient human chorionic gonadotropin variants produced by site directed mutagenesis and chemical deglycosylation.

Appropriate glycosylation of gonadotropins is essential for the full expression of their biological activity. In this investigation we have compared the properties of glycosylation deficient human chorionic gonadotropin (hCG) produced by chemical deglycosylation (HF treatment--DG-hCG) or recombinant techniques (site directed mutagenesis). Among the recombinant hCG molecules secreted into the culture medium, the following variants containing selective N-glycosylation deletions at delta alpha 1 or delta alpha 1,2 or in both subunits could not stimulate steroidogenesis in mouse Leydig tumor cells (MA-10 cell line) and in this respect were very similar to DG-hCG. The other variants were fully active like native hCG, but the alpha + delta beta 1,2 recombinant hCG was a partial agonist. In radioimmunoassay with antibodies against native hCG, the DG-hCG as well as all recombinant hCG variants, including the wild type (WT), were similar. However, with antisera against DG-hCG or affinity purified antibodies specific to DG-hCG the alpha/delta 1,2 beta mutant, the WT hormone and native hCG were less active. In this assay mutants containing N-glycosylation deletions in the alpha subunit as well as the delta alpha 1,2/delta beta 1,2, variant showed higher activity. A similar pattern was evident in reaction with a selected monoclonal antibody showing preferential binding of 125I-labeled DG-hCG (antagonist). Affinity purified antibody directed against native hCG conformation was successful in converting DG-hCG and some inactive glycosylation deficient variants into an active form by stimulating progesterone in MA-10 cells. These data suggest that there are similarities as well as subtle differences in conformation of DG-hCG and various recombinant hCG molecules.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regulation of human chorionic gonadotropin (hCG) secretion by serum and dibutyryl cyclic AMP in malignant trophoblast cells in vitro.

Human chorionic gonadotropin (hCG) secretion was studied in human malignant trophoblast cells (Jar line) in continuous culture. Radioimmunoassayable hCG in the cells and in the daily culture fluid was increased for at least 3 days by 10% newborn calf serum and by 1 mN N-6, 0-2'-dibutyryl cyclic adenosine 3', 5'-monophosphoric acid (dbcAMP) plus 1 mM theorphylline. Incubation of the cells in the presence of serum, dbcAMP and theorphylline resulted in additive stimulation of hCG secretion after 1 day.After 2 or 3 days, a supra-additive stimulation was observed, which was prevented by Actinomycin D. When cells were preincubated for 2 days in the absence of serum but with dbcAMP plus theorphylline, subsequent addition of serum resulted in supra-additive stimulation of hCG secretion within a single day; the continued presence of dbcAMP plus theophylline was not necessary for this stimulation by serum. These findings suggested that dbcAMP activates a slow process requiring RNA synthesis, resulting in increased hCG secretion. Serum appears to protect the hCG synthesizing system from degradation.     

Serologic discrimination of human T cell lymphotropic virus infection by using a synthetic peptide-based enzyme immunoassay

Synthetic peptides corresponding with unique regions of the envelope glycoproteins (gp46) of human T cell lymphotropic viruses (HTLVs) were used in an enzyme immunoassay to determine if HTLV-I and -II infections could be discriminated. Two synthetic HTLV-I sequence-derived peptides, Env-1 (amino acids 191-215) and Env-5 (amino acids 242-257), reacted with 92% and 100% of the serum specimens (n = 52) from HTLV-I-infected persons, respectively. Although a small percentage (8.6%) of serum specimens from persons infected with HTLV-II cross-reacted with Env-1, none of these specimens reacted with Env-5. Peptide Env-2 encoded by the envelope region of HTLV-II (amino acids 187-210) reacted with serum specimens from both HTLV-I (94%)- and HTLV-II (74%)-infected patients, whereas Env-6, another HTLV-II peptide (amino acids 238-254), reacted with less than 6% of the specimens. Therefore, the Env-5 peptide with amino acid sequence SerProAsnValSerValProSerSerSerSerThrProLeuLeuTyr represents an immunodominant domain of HTLV-I that is recognized by serum antibodies from all HTLV-I-infected persons. Moreover, the Env-5-based ELISA allows a categorical distinction between the closely related HTLV-I and -II infections.     

A procedure using immobilized antibody for the isolation of the beta-subunit of human chorionic gonadotropin from the culture fluid of a beta-subunit-secreting nontrophoblastic cell line

Antibody produced against the beta-subunit of hCG was linked to Sepharose 4B and used to isolate ectopic hCG beta secreted by DoT cervical cancer cells in culture. beta-Subunit was eluted with 3 M guanidine-hydrochloride, pH 3.0 (three treatments, 15 min each, at 20 C). The eluted hCG beta was desalted with Sephadex G-25 and concentrated by lyophilization. A single batch of antibody-bound Sepharose was used repeatedly to adsorb hCG beta from liter quantities of spent culture fluid containing 10% fetal bovine serum. The material recovered from 15.75 liters of fluid was pooled and treated a second time with immobilized antibody. Using only immobilized antibody, purification of more than 200,000-fold was achieved, with an overall recovery of about 28%.