Human chorionic gonadotropin and free beta subunits stimulate phospholipid methylation in intact rat Leydig cells

The free beta-subunit of human chorionic gonadotropin as a prognostic factor in renal cell carcinoma

The free beta-subunit of human chorionic gonadotropin beta is expressed in several nontrophoblastic tumours and this is usually associated with aggressive disease. Little is known about human chorionic gonadotropin beta expression in renal cancer. We determined the pretreatment levels of human chorionic gonadotropin beta in serum of patients with renal cell carcinoma, and studied whether elevated levels predicted the clinical outcome. Serum samples were collected before surgery from 177 patients with renal cell carcinoma and from 84 apparently healthy controls. Human chorionic gonadotropin beta in serum was measured by a highly sensitive time-resolved immunofluorometric assay. The prognostic value of human chorionic gonadotropin beta, and of usual clinical and pathological variables was analyzed by the Kaplan-Meier method, the log rank test and Cox multiple hazard regression. The serum concentrations of human chorionic gonadotropin beta were increased in 23% of the renal cell carcinoma patients and they were significantly higher in patients with renal cell carcinoma than in controls (P<0.0001). The concentrations did not correlate with clinical stage and histopathological grade, but patients with increased human chorionic gonadotropin beta levels had significantly shorter survival time than those with levels below the median (cut-off 1.2 pmol l(-1), P=0.0029). In multivariate analysis human chorionic gonadotropin beta, tumour stage and grade were independent prognostic variables. The serum concentration of human chorionic gonadotropin beta is an independent prognostic variable in renal cell carcinoma. The preoperative value of human chorionic gonadotropin beta in serum may be used to identify patents with increased risk of progressive disease.

Preoperative serum concentration of hCGbeta as a prognostic factor in ovarian cancer

In spite of a gradual improvement, survival in epithelial ovarian cancer is disappointingly low. New therapeutic regimens are emerging, and it would be important to be able to predict the prognosis and to stratify patients for clinical trials before therapy. We have evaluated the prognostic value of the pretreatment serum concentrations of 3 tumor markers. The free beta subunit of human chorionic gonadotropin (hCGbeta), CA125 and tumor-associated trypsin inhibitor (TATI) were measured in pretreatment serum samples from 146 patients treated for ovarian cancer between 1990-1995. The patients were followed up until 1998. Elevated concentrations of hCGbeta, CA125 and TATI were observed in 29%, 79% and 33%, respectively. When tested as single variables in Cox's proportional hazards model, stage, grade, size of residual tumor and hCGbeta (all p < 0.001) and CA125 (p = 0.004) correlated with prognosis. However, when fitted as multiple variables together with stage, grade and age in the same model, hCGbeta (RR = 3.42) stage (RR = 2.77) and grade (RR = 3.80) were the only significant variables. When serum hCGbeta was normal, 5-year survival was 80%, but it was only 22% when hCGbeta was elevated. In patients with stage III or IV and minimal residual disease, 5-year survival was 75% if hCGbeta was normal compared with 0% if hCGbeta was elevated. hCGbeta in serum is a strong independent prognostic factor in epithelial ovarian cancer, and its prognostic value is similar to that of grade and stage. The availability of this marker before surgery could facilitate selection of treatment modalities.

Concentration of free hCGbeta subunit in serum as a prognostic marker for squamous-cell carcinoma of the oral cavity and oropharynx

This study was conducted to evaluate the clinical usefulness of serum hCGbeta in the diagnosis and prognosis of patients (n = 59) with cancers of the oral cavity and oropharynx. As a reference marker we used squamous-cell carcinoma antigen (SCCAg). A blood sample was obtained from all patients before primary surgery. Serum hCGbeta was determined by a time-resolved immunofluorometric assay (IFMA) and SCCAg by a solid phase immunoenzymometric assay. Elevated preoperative hCGbeta levels were observed in 8 (14%) and elevated SCCAg in 12 (20%) out of 59 patients. Patients with preoperatively elevated hCGbeta had a shorter recurrence-free survival when compared with those with normal hCGbeta levels (log-rank Chi-squared = 6.83, p =.009), and the risk-ratio for recurrence during follow-up for those was 3.6 (95% CI = 1.29-9.94). In a Cox multivariate model hCGbeta (p = 0.039) and stage (p = 0.044) were independent prognostic factors. SCCAg showed no correlation with recurrence-free survival. We conclude that determination of hCGbeta in serum is a potential marker in the prognostic evaluation of patients with SCC of the oral cavity and oropharynx.

Pathophysiological importance of various molecular forms of human choriogonadotropin

Human chorionic gonadotropin (hCG), its subunits and fragments are widely used for diagnostic purposes. In addition to the diagnosis of pregnancy and pregnancy related disorders, hCG determinations are used for diagnosis of trophoblastic and recently also nontrophoblastic tumors. The use for diagnosis of nontrophoblastic tumors requires highly specific and ultrasensitive assays. With these, it is possible to measure the concentrations of both hCG, the free beta-subunits and the so called beta-core fragment in healthy subjects. Therefore it is important to establish reference values for these and also to be aware of the influence of physiological factors on the serum and urine concentrations. Improved standardization of the assay methods is also essential for these novel applications of hCG determinations to become useful.

Leydig cell heterogeneity as judged by quantitative cytochemistry of 3 beta-hydroxysteroid dehydrogenase activity in individual rat Leydig cells

3 beta-Hydroxysteroid dehydrogenase (3 beta-HSD) is one of the key enzymes involved in the steroidogenic pathway of Leydig cells. In this study, quantitative cytochemistry was used to detect the 3 beta-HSD staining intensity in individual rat Leydig cells. The measurement of the intensity of staining was a reliable method reflecting the relative amount of 3 beta-HSD activity. The objective was to determine the presence, basal and hCG-mediated effect of 3 beta-HSD activity in individual Leydig cells. 3 beta-HSD cytochemistry was performed in both, 8 and 12 microns diameter rat Leydig cells. The results showed that both populations of Leydig cells have different basal 3 beta-HSD activity. The 8 microns cells showed a greater basal 3 beta-HSD activity than the 12 microns cells when their optical density values were normalized to their size. A difference in regulation of the enzymatic activity by LH/hCG was observed in the two types of Leydig cells. Incubation of the whole population of Leydig cells with hCG (1IU), decreased the 3 beta-HSD activity in the 8 microns cells, but increased the activity in the 12 microns cells. The results describe for the first time that the 3 beta-HSD activity may be differentially regulated by LH/hCG in Leydig cells.

Agents that increase phosphatidic acid inhibit the LH-induced testosterone production

The results of the present study point to phosphatidic acid (PtdOH) as a possible intracellular messenger, which might be involved in local modulation of testicular testosterone production in vivo. Propranolol (27-266 microM) induced an increased level of [3H]PtdOH in isolated rat Leydig cells, prelabeled with [3H]myristate, and at the same time a strong dose-dependent inhibition of the acute testosterone production stimulated by luteinizing hormone (LH). The inhibition was not bypassed by the addition of dibutyryl-cAMP but was overcome, when 22(R)-hydroxycholesterol was added as a direct substrate for cytochrome P-450 side chain cleavage enzyme. Thus, the inhibition appears to be exerted at a point distal to cAMP-generation but before the first enzyme in the testosterone synthetic pathway. Treatment with other agents (4 beta-phorbol 12-myristate 13-acetate (PMA), A23187, and sphingosine) giving rise to increases in the PtdOH-level resulted in the inhibition of the LH-induced testosterone formation as well, thus indicating a connection between the two effects. Furthermore, we were able to demonstrate a highly significant correlation between the PtdOH-increase and the inhibition of the LH-stimulated testosterone production. This may suggest a causal relationship between these two parameters.