Biological Properties of hCG after Removal of Terminal Sialic Acid and Galactose Residues

Tsuruhara, T.; Dufau, Maria L.; Hickman, Jean; Catt, K. J.

doi:10.1210/endo-91-1-296

Cited by 99 publications

(21 citation statements)

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“…One possible reason may be that bacterial CG-like factor has low sialic acid content. It is well known that desialylated hCG possesses extremely low biological activity in vivo due to its more rapid removal from the blood (17,18). In spite of this, desialyted hCG retains full activity in the RRA and RIA systems.…”

Section: Resultsmentioning

confidence: 99%

Production of choriogonadotropin-like factor by a microorganism.

Maruo¹,

Cohen²,

Segal³

et al. 1979

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

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Extracts from an acetone powder preparation of a culture of a microorganism tentatively named Progenitor cryptocides contain choriogonadotropin (CG-like factor as determined by radioimmunoassay with antiserum to human (h)CG # subunit COOH-terminal peptide and radioreceptor assay with bovine corpus luteum membranes. Possible interference by proteases in the extracts was excluded. Immunoreactive materials reacting with antisera to hCG 0 subunit and hCG P subunit COOH-terminal peptide were also found in the extracts. No free a subunit was detected. The CClike factor was purified by chromatography on Sephadex G-100, concanavalin A-Sepharose, and DEAE-Sephadex A-50. The factor was adsorbed by concanavalin A-Sepharose, suggesting that it contains mannose and glucose moieties. The factor was eluted at the same position as standard hCG on Sephadex G-100. It dissociated into two bands when subjected to sodium dodecyl sulfate/polyacrylamide gel electrophoresis; the bands corresponded to the respective standard hCG subunits. The biological activity of the purified factor as determined by the rat uterine weight assay and the ovarian weight assay was equivalent to 380 (95% confidence limits: 320-490) and 880 (780-1020) international units/mg, respectively. It can be concluded from the present results that a microorganism produces a glycoprotein that is biologically active and has physicochemical properties similar to those of hCG.Human (h-) choriogonadotropin (CG) is a glycoprotein hormone normally produced by the placenta and considered to be a specific hormone of pregnancy and trophoblastic neoplasms. However, it has been reported that nontrophoblastic malignant tumors (1, 2) and normal human tissues (3) produce CG Related to the problem of extraplacental production of CG, there are reports suggesting that CG is produced by a microorganism (5, 6). However, in the measurements in these studies, possible interference by proteases in the bacterial extracts was not excluded. In the present study, we will show that a CG-like factor is produced by a microorganism and that the observed results are not due to proteases. The factor has been purified and found to be biologically active, and it has immunological and physicochemical properties similar to those of hCG. MATERIALS AND METHODS Bacterial Extracts. A microorganism tentatively namedProgenitor cryptocides was obtained from V. W.-C. Livingston (5). Cultures of the microorganism were maintained on Muller-Hinton slants. Inoculation of 250 ml of trypticase/yeast extract medium in a 500 ml Erlenmeyer-flask was performed with a single colony from the Muller-Hinton slant. To a 28-liter fermenter, 20 liters of trypticase/yeast extract medium was added and the fermenter was inoculated with an overnight growth of the organism in the 250 ml of medium described above. After incubation for 120 hr at 37°C, the entire culture content was harvested and an acetone-dried powder was prepared according to a prescribed method (5), by J. Majnarich, Biomedical Research Laboratory. Twenty ...

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Section: Resultsmentioning

confidence: 99%

Production of choriogonadotropin-like factor by a microorganism.

Maruo¹,

Cohen²,

Segal³

et al. 1979

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

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“…Variability of the relative concentration of intact hormone and free subunits, together with heterogeneous glycosylation of the protein chains, has also been reported in studies on patients with a variety of other tumour types (Weintraub & Rosen, 1973;Rosen & Weintraub, 1974;Kahn et al, 1977;Yoshimoto et al, 1979b). The degree of glycosylation affects various biochemical characteristics and also the rate of metabolism in vivo (Van Hall et al, 1971;Tsuruhara et al, 1972). Independent production of subunit and intact hormone is not surprising as there is evidence that the genes for the alpha and beta subunits may be on different chromosomes.…”

Section: Resultsmentioning

confidence: 86%

In vitro secretion of human chorionic gonadotrophin by bladder tumour cells

Iles¹,

Oliver²,

Kitau³

et al. 1987

Br J Cancer

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Summary Human chorionic gonadotrophin (hCG) and alphafetoprotein (AFP) were measured in culture media from a panel of 29 cell lines including 9 bladder carcinomas, 5 'normal' bladder epithelia, 10 germ cell tumours, and 5 miscellaneous tumours and 'normal' cell lines. In 7 of the 9 bladder carcinomas and 4 of the 5 'normal' bladder epithelia, the media contained hCG at levels ranging from between 34 and 3,600 IU I -. All other cell lines, including the 10 germ cell tumour lines gave negative results for hCG. These findings indicate that in vitro secretion of hCG is a common feature of normal and neoplastic bladder transitional epithelia, and support the hypothesis that parts of the genito-urinary epithelium have a potential for hCG production.The high incidence of elevated levels of human chorionic gonadotrophin (hCG) and alphafetoprotein (AFP) in association with testicular germ cell tumours is wellrecognised in vivo (Seppala et al., 1986), but this phenomenon is relatively uncommon during culture of these tumours (Andrews et al., 1980). Ectopic production of hCG is also a well-recognised phenomenon in some non-gonadal epithelial tumours (Braunstein et al., 1973;McManus et al., 1976;Bellet et al., 1980). This is particularly common in gastric (24%), hepatic (17%) and pancreatic (50%) cancers (reviewed by Baylin & Mendelsohn, 1980;Heyderman et al., 1985;Seppala, 1986 al., 1986). Immunohistochemical studies suggest that ectopic production of hCG is relatively unusual in bladder tumours with reports varying from 5 of 13 to 12 of 104 cases (Rodenburg et al., 1985;Shah et al., 1986). In the present study we have examined hCG and AFP secretion by normal and neoplastic bladder and testicular germ cell tumours in vitro. Materials and methodsA total of 29 cell lines were examined in this study (Table I). They included: 14 lines of urothelial origin (9 neoplastic (see Table I), 5 'normal'); 10 germ cell tumours (gonadal) and 5 miscellaneous tumours and 'normal' controls. The American Type Culture Collection (ATCC) and other lines held at the London Hospital were grown in a medium consisting of Leibowitz L-15 RPMI 1640 (50/50, v/v) containing 20% heat inactivated foetal calf serum (FCS), transferrin (4 pg ml -1), hydrocortisone (4 ng ml -1), insulin (4 Mg ml -1), and penicillin-streptomycin (1,000 U ml-1) (Gibco Ltd., Paisley, Scotland). Cell lines from the Institute of Urology were grown RPMI 1640 plus 5% FCS (Gibco). Incubation was carried out at 37°C in a mixture of 95% air and 5% CO2. The cell lines were grown to confluence in culture flasks (75 cm adherence area; Falcon Labware).

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“…Note that this peak of hCGf# conformational immunoreactivity was shifted to the right of the position of the cochromatographed purified '25I-hCG; thus, most of the hCG in this specimen displayed a smaller apparent molecular size than authentic hCG. The slightly greater elution volume of this form of hCG in conjunction with its activity in the hCGB as-CTP RIA indicated a sizeable degree of desialylation of the hCG in fractions [25][26][27][28][29][30][31][32][33][34][35][36][37] (32).…”

Section: Resultsmentioning

confidence: 99%

“…We have deduced that this form of hCG contains desialylated O-serine-linked carbohydrate chains from its cross-reactivity in the hCG# as-CTP RIA. While the degree of desialylation of its N-asparagine-linked carbohydrate chains cannot be deduced from this observation, it is noteworthy that this form of as-hCG did cochromatograph with the as-hCG molecule, and like as-hCG (32,33), it adsorbed to Con A and interacted with the LH/CG receptor. Studies of choriocarcinoma cell lines cultured in vitro have provided evidence that the secreted forms of hCG can vary considerably in their degree of sialylation (42).…”

mentioning

confidence: 85%

Characterization of a carboxyterminal peptide fragment of the human choriogonadotropin beta-subunit excreted in the urine of a woman with choriocarcinoma.

Amr¹,

Wehmann²,

Birken³

et al. 1983

J. Clin. Invest.

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A B S T R A C T We have observed low-molecular weight carboxyterminal fragments of the human choriogonadotropin (hCG) a-subunit in the urines of several women with choriocarcinoma, and we have characterized one fragment in detail. Its apparent molecular weight by gel chromatography on Sephadex G-100 was 14,200. The fragment was not adsorbed to concanavalin A-Sepharose, indicating that it lacked the asparagine-linked carbohydrate groups of intact hCG#. It was active in radioimmunoassays (RIA) using antisera either to the hCG# carboxyterminal peptide (CTP) or to the desialylated hCG# CTP (hCG# as-CTP), indicating the presence of not only the hCG# carboxyterminus but also desialylated O-serine-linked carbohydrate side chains on the fragment. It lacked luteinizing hormone/choriogonadotropin radioreceptor activity and hCG# conformational immunoreactivity (SB6 RIA). On Sephadex G-100 gel chromatography, the elution profiles of this fragment and the hCG# as-CTP(115-145) prepared by trypsin digestion of ashCG were essentially indistinguishable (apparent molecular weights 14,200 and 14,000, respectively). The immunological characteristics of the fragment in both hCG# CTP and hCG# as-CTP RIA were indistinguishable from those of the hCG,6 as-CTP(115-145) glycopeptide. Carboxyterminal fragments of hCG# were evident in urine specimens obtained from 10 of 11 patients with choriocarcinoma but not in those ob-

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Biological Properties of hCG after Removal of Terminal Sialic Acid and Galactose Residues

Cited by 99 publications

References 0 publications

Production of choriogonadotropin-like factor by a microorganism.

Production of choriogonadotropin-like factor by a microorganism.

In vitro secretion of human chorionic gonadotrophin by bladder tumour cells

Characterization of a carboxyterminal peptide fragment of the human choriogonadotropin beta-subunit excreted in the urine of a woman with choriocarcinoma.

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