Immunohistochemical demonstration of chorionic gonadotrophin in trophoblastic tumors

The diagnostic significance of hCG and hPL via immunohistochemistry of placental tissues in pregnancies diagnosed with IUGR and IUD

Placentas of patients diagnosed with intrauterine growth restriction (IUGR) and intrauterine death (IUD) were examined by immunohistochemistry for alpha-beta subunits of human chorionic gonadotropin (hCG) and human placental lactogen (hPL) antibodies, and compared with placentas from women with healthy pregnancies. In total, 114 subjects were evaluated. The patient group comprised 27 cases of IUGR and 57 of IUD, and the control group consisted of 30 women with normal pregnancies. Placental specimens were examined for primary antibodies using immunohistochemical techniques. Placentas from 22 cases of IUGR were stained positively for alpha-hCG. All 27 specimens obtained from this group were stained positively for beta-hCG and hPL. Among the cases of IUD, 44 placentas were stained positively for alpha-hCG, and all 57 specimens were stained positively for beta-hCG and hPL.

Regulation of telomerase during human placental differentiation: a role for TGFbeta1

The transient tumor-like attributes of the first-trimester placenta anchor the developing embryo to the uterine wall thus establishing a vital link between the mother and the fetus. Dysregulation of this invasive behavior and/or controlled proliferation of the placenta is associated with abnormal pregnancies. Several of these diseased states also exhibit aberrant telomerase activity, among other pathophysiological manifestations. Considering the strong correlation between telomerase activity and tumorigenesis, it was of interest to see whether the crucial processes of trophoblast proliferation and differentiation were brought about through the modulation of telomerase. Using two in vitro model systems of trophoblast differentiation, we demonstrate here that telomerase activity is negatively regulated during placental differentiation. We further show that this modulation is at the level of transcription of hTERT. We also propose a role for TGF beta1 in regulating telomerase activity in differentiating trophoblasts by down-regulating the expression of hTERT at the transcriptional level.

Immunolocalization of alpha and beta chains of human chorionic gonadotropin, placental lactogen and pregnancy-specific beta-glycoprotein in term placenta by a touch preparation method

Touch preparations of human placenta yield cells retaining antigenic reactivity to immunoperoxidase stains for alpha and beta chains of human chorionic gonadotropin, placental lactogen, and pregnancy-specific beta glycoprotein. This method is a rapid and simple alternative to conventional frozen and paraffin-embedded sections for detection of placental peptides.

Effect of cytochalasin B on growth, Multinucleation and human chorionic gonadotropin secretion in a human choriocarcinoma cell line

Treatment of human choriocarcinoma cells with cytochalasin B at the doses of inhibiting cell division but not inhibiting nuclear division led to in vitro formation of the multinucleated syncytiotrophoblast-like ( STL ) cells. A concomitant increase in human chorionic gonadotropin (hCG) secretion per cell was noted. Immunocytochemical staining demonstrated the predominant localization of hCG in the STL cells. These results indicate that multinucleation stimulates hCG synthesis and secretion in the choriocarcinoma cells.

Enhancement of human chorionic gonadotrophin production by antimetabolites

The action of methotrexate, actinomycin D, bleomycin, vincristine and hydroxyurea on the production of human chorionic gonadotrophin (hCG) by a choriocarcinoma cell line (BeWo) has been studied. hCG production per unit of cell protein was increased, and this was a continuing process only halted by cell death. The proportion of hCG-producing cells in the population increased from approximately 5% to a maximum of approximately 40% during incubation with vincristine. A possible explanation for these and related observations is that cytotoxic agents promote the differentiation of cytotrophoblast to syncytium. A similar mechanism could contribute to the unusual sensitivity of choriocarcinoma to cytotoxic agents.

Cytological localization of chorionic gonadotropin alpha and placental lactogen mRNAs during development of the human placenta

Probes derived from clones bearing cDNAs corresponding to the alpha subunit of human chorionic gonadotropin (hCG) and human placental lactogen (hPL) were used to localize their respective mRNAs cytologically in sections of first trimester and term human placenta. hPL mRNA was exclusively localized to the syncytial layer, hCG alpha mRNA was found in the syncytial layer and also in some differentiating cytotrophoblasts. Hybridization was specific because no signal was observed when labeled pBR322 was hybridized to placental sections or when the placental probes were hybridized to sections of human tonsils. In addition, RNA in placental interstitial cells did not hybridize with hCG alpha and hPL probes. Hybridization with the hCG alpha probe was much greater in first trimester than in term sections, whereas hPL signals were comparable in both first trimester and term placentae. Syncytial formation proceeds through cellular intermediates of cytotrophoblastic origin, and the data suggest that transcription of the hCG alpha gene is initiated before the completion of syncytial formation. In contrast, hPL mRNA synthesis starts later in trophoblast differentiation, likely after the stage of syncytial formation. The data also suggested that hCG alpha mRNA synthesis becomes attenuated but that hPL is transcribed at a rather constant rate during placental development.

Differential expression of trophoblast-specific membrane antigens by normal and abnormal human placentae and by neoplasms of trophoblastic and non-trophoblastic origin

Using a specific antiserum to human syncytial trophoblast plasma membrane (TrPM), we have investigated the expression of these antigens on a variety of trophoblastic and non-trophoblastic tissues by a standard peroxidase/anti-peroxidase staining method. Normal placenta (first-trimester as well as full-term), placenta from tubal pregnancy and placenta accreta were all found to express TrPM antigens. However, malignant change in trophoblast neoplasms appeared to by accompanied by a loss of these antigens, with 7 out of 10 specimens of hydatidiform mole staining positively while 3 specimens of invasive mole and 7 specimens of choriocarcinoma were all negative. In contrast, a number of malignant tumours of non-trophoblastic origin such as carcinomas of the colon, cervix, bladder and hepatomas were found to express TrPM antigens. The possible significance of the reversal to a trophoblast phenotype by malignant neoplasms of non-trophoblastic origin is discussed.