Enhancement of the detection of alkali-resistant phosphoproteins in polyacrylamide gels

Following their separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, labeled proteins obtained from cultured canine prostatic epithelial cells incubated with [35S]-methionine and [32P]phosphate were subjected to alkali treatment, a method that is currently used to detect phosphotyrosine-containing proteins. Significant amounts of 35S-labeled material were lost during the alkali treatment. The crosslinking of proteins within the gels by glutaraldehyde treatment eliminated protein losses and did not alter the efficiency of phosphoester bond hydrolysis by alkali treatment. Consequently, the time required to detect alkali-resistant phosphoproteins by autoradiography was greatly reduced. Prostatic phosphoproteins were also shown to contain phosphotyrosine, indicating the presence of tyrosine protein kinase activity in these proliferating epithelial cells.

Photoperiodic influence on the morphology and the androgen receptor level of the ventral prostate gland and seminal vesicles of the Djungarian hamster (Phodopus sungorus)

The influence of long (light:darkness LD 16:8) and short (LD 8:16) photoperiods on the morphology of the ventral prostate gland and the seminal vesicles of the Djungarian hamster was investigated. At LD 8:16, the wet weight of the glands was reduced to 15-20% of the values found in animals living in LD 16:8 conditions, the protein content was reduced to 3-4%. The glands showed distinct signs of atrophy and inactivity under short-day conditions. The androgen receptor levels were determined in both accessory sex glands. The receptor levels were comparable in both glands; the absolute values related to the whole glands remained about constant in animals living in long and short photoperiods despite a reduction of the androgen levels in short photoperiods.

Quantitative assessment of endogenous testicular and adrenal sex steroids and of steroid metabolizing enzymes in untreated human prostatic cancerous tissue

Total tissue content and subcellular distribution of DHEA sulfate, DHEA, androst-5-ene-3 beta,17 beta-diol, androst-4-ene-3,17-dione, testosterone, 5 alpha-DHT, and 5 alpha-androstane-3 alpha,17 beta-diol as well as the activities of steroid sulfate-sulfatase, 17 beta-hydroxysteroid dehydrogenase, 5 alpha-reductase, 3 alpha/beta-hydroxysteroid dehydrogenase, and creatine kinase were quantified in 12 untreated primary tumors of prostatic cancer. Samples were obtained by radical prostatectomy and serial sections, and were alternately used for either biochemical or morphological evaluation. The results were compared with values determined in benign parts of the same prostates. Qualitatively, all enzymes and steroids found in the benign tissues could also be demonstrated in the cancers. Steroid patterns showed individual quantitative variation but no general differences between the carcinomas and the benign tissues. Enzymes showed a tendency to lower activities in the cancers, particularly when expressed per DNA. Substantial diminutions of creatine kinase and 5 alpha-reductase activity, the latter being often accompanied by an increased testosterone/DHT ratio, were the most striking differences seen in most of the cases between malignant and nonmalignant tissues. Some interesting individual parallels of morphological and biochemical aspects were seen, but there was no obvious general parallelism between the histological picture and endocrinological characteristics.

Expression of basic fibroblast growth factor mRNA in benign prostatic hyperplasia and prostatic carcinoma

In our previous work we demonstrated that prostate-derived growth factor (PrGF) is homologous to basic fibroblast growth factor (bFGF), not acidic fibroblast growth factor (aFGF). Using Northern blot analysis we now show that the messenger RNA for bFGF but not aFGF is expressed in benign prostatic hyperplastic (BPH) tissue as well as in carcinoma of the prostate (CAP). This not only corroborates our previous results, but suggests that PrGF is produced locally and not merely stored in the prostate. The demonstration of local production of bFGF by prostate tissue may indicate that this growth factor plays a role, either alone or in conjunction with other factors, in the etiology of benign hyperplasia or prostatic cancer.

Prostate-specific antigen (PSA) in the management of 500 prostatic patients

Blood samples from 500 patients with clinical prostatic symptoms were radioimmunoassayed with prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP) kits. On the basis of histological data, directed by PSA results and other investigations, 200 prostatic cancers (adenocarcinomas), 276 benign prostatic hypertrophy (BPH), 16 cases of prostatitis, 5 cancers of the bladder, and 3 prostatodynias were diagnosed. All of the serum samples from prostatic cancer patients showed elevated PSA levels at diagnosis, whereas about 70% of these showed normal PAP values. The sensitivity of the PSA assay is 100% when 2.5 ng/ml is taken as the upper limit of normal. However, the specificity and the positive predictive value are better at 10 ng/ml: 99 and 79%, respectively. High PSA values alerted the clinician when diagnosing a cancer without symptoms on rectal or ultrasonographic examination (3%). In BPH, when the PSA level is between 2.5 and 10 ng/ml, a PSA control must be performed within 2 months. If PSA increases above 10 ng/ml, the risk of cancer has to be considered. In the follow-up, PSA is a better marker than PAP to detect disease progression and seems to constitute an evolutive tumor mass index. PSA is the most sensitive, the earliest, and the most prognostically reliable marker for diagnosis and follow-up of prostate cancer patients.

Evaluation of prostate-specific antigen in prostate cancer

Prostate-specific antigen (PSA) was assayed retrospectively in 131 prostate cancer patients. Pretreatment levels at primary tumor diagnosis were above 5 ng/ml in 13/16 (81%) of stage B and C patients and in 28/28 (100%) of stage D (D1 and D2) patients. At the discovery of metastasis in treated patients, they were above this value in 12/17 (71%) of patients. To determine the value of PSA assays when physical exams were negative, 52 patients were reevaluated at a maximum interval of 12 months as a function of their initial PSA concentration. When the initial PSA was negative, there was no clinical evolution during the next 6 months; when PSA was positive, patients had a 55% risk of progression in the next 4 months. All PSA assays were coupled with prostatic acid phosphatase (PAP) measurements. No PAP values were positive when PSA was negative.

Immunocytochemical demonstration of insulin or insulin-like immunoreactivity in the rat prostate gland

The indirect immunocytochemical technique was used in conjunction with anti-insulin antisera to localize insulin-like immunoreactivity in tissue sections and primary cell cultures from rat prostate gland. Positive immunostaining for insulin-like reactivity was demonstrated in the epithelium of the prostate gland. There appeared to be some variation in the intensity and localization of the immunoreactivity within different regions of the gland. Prostatic epithelial cells grown in culture in an insulin-free medium displayed strong cytoplasmic immunostaining when treated with anti-insulin antisera, while nuclear staining was absent. These results demonstrate that insulin-like immunoreactivity is present in the epithelium of the prostate gland and suggest that there may be some local insulin or insulin-like synthesis in this organ.

Three predominant proteins secreted by the human prostate gland

Analyses of the proteins of azoospermic ejaculates from subjects with defective seminal vesicles demonstrated that three prostatic-secreted proteins were predominant. Prostatic acid phosphatase (PAP), prostate-specific antigen (PSA; or gamma-seminoprotein), and beta-microseminoprotein (beta-MSP; or beta-inhibin), were identified as the three predominant proteins secreted by the normal human prostate gland. Immunohistochemical localization of these proteins, in the epithelium of normal prostatic acini and ducts, with the avidin-biotin complex procedure demonstrated that each PAP-immunoreactive cell was invariably immunoreactive both with PSA-and beta-MSP-monospecific antisera as well.

The Ca2+-dependent protease inhibitor of rat ventral prostate: properties of the inhibitor and effects of castration on Ca2+-dependent protease and inhibitor activities

1. The rat ventral prostate contains a heat stable inhibitor of Ca2+-dependent protease. This inhibitor was found to exist in a wide range of molecular weights (approx. 40-270 kDa) in adult rats. 2. However, in rats immediately post puberty (45 days of age) the inhibitor was predominantly of the higher molecular weight forms. 3. The inhibitor was also found in the dorsolateral and anterior (coagulating gland) prostate lobes but was of lower specific activity than in the ventral lobe. 4. Although the activities of the Ca2+-dependent protease and inhibitor decreased per ventral prostate gland after castration, these activities were not different during the first 10 days postcastration when expressed per g wet wt or per unit cytosol protein. 5. With a longer duration of castration, there was a decline in the specific activity (per unit protein) of the protease and an increase in that of the inhibitor. 6. Thus, the activities of the protease and inhibitor change in concert with the amount of cellular cytosol protein during the active period of castration-induced atrophy. 7. However, in long term castrated rats, functions carried out by the Ca2+-dependent protease may be effectively suppressed. 8. These data suggest that the Ca2+-activated protease probably is involved in the regulation of some metabolic processes in the active gland and is not prominent in the castration induced atrophy of the ventral prostate unless it functions through the proteolysis of some select protein(s).

Significance of PSA and PAP in patients with or without prostatic cancer

Coupled prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP) measurements (using the radioimmunoassay method) were carried out on 220 controls, 33 patients with prostatic hyperplasia, and 71 with carcinoma. The mean PSA value was 3.70 +/- 3.31 ng in the controls. A level of 10 ng was adopted as the upper limit of normal. Four of the eight cases of prostatic hyperplasia with a high PSA level (between 10 and 25 ng) underwent surgery. Histological tests confirmed benign hyperplasia. In the localized cancers, the PSA level was normal. In the metastatic cancers, PSA proved to be more sensitive than PAP. Thus, PSA is of little use in the early diagnosis of cancer; its systematic measurement as a means of cancer screening for the general public may even be misleading.

Prolactin and luteinizing hormone-releasing hormone receptors in human benign prostatic hyperplasia and prostate cancer

Using a sensitive micromethod for the determination of prolactin (PRL) binding sites based on 125I-human PRL ligand, PRL receptor levels in specimens of benign prostatic hyperplasia (BPH) and human prostate cancer were estimated by the one-point assay system. Ten of 19 BPH specimens (53%), showed significant PRL binding, four being in the 9-12 fmol/mg range. All ten of these cases had an histological diagnosis of nodular glandular hyperplasia. Of ten adenocarcinomas examined, four samples (40%) exhibited positive PRL binding, the highest receptor levels being 10.2 fmol/mg protein. To characterize the receptors from BPH membranes, samples were then separately pooled according to the results obtained in one-point assays. In the PRL-negative pool no displacement could be detected. In the PRL-positive pool, the Scatchard analysis revealed one class of receptors with an average affinity Kd = 1.1 X 10(-9) M and capacity Bmax = 287 fmol/mg protein. In the prostate cancer specimens, luteinizing hormone-releasing hormone receptors with a high affinity and a low capacity were also found. The results indicate the presence of prolactin receptors in prostate cancer and in BPH. The clinical implications of such findings are not clear, but it is possible that a certain proportion of BPH and prostate cancers might be in part PRL dependent. Further studies are necessary to ascertain this hypothesis in an attempt to improve the treatment of BPH and prostate cancer.

Modulation of rat prostatic inhibinlike peptide (PIP) by steroids and protein hormones

Prostatic inhibinlike peptide (PIP) was detected in the ventral but not in the dorsal lobe of rat prostate. On orchiectomy, PIP concentration in the ventral prostate increased significantly, whereas it decreased on testosterone administration and attained value comparable with that in intact control. Estradiol-17 beta treated animals exhibited high levels of PIP in absence of significant alterations in the protein content. The effect of prolactin and human chorionic gonadotropin on PIP concentration was not so prominent at the dose levels studied. The present study thus demonstrates negative regulation of PIP by testosterone and stimulatory effect of estradiol-17 beta on PIP in rat ventral prostrate.

Comparative analysis of growth factors in normal and pathologic human prostates

Growth factors, as detected by DNA synthesis stimulating activity for BALB/c 3T3 cells, in normal, benign hypertrophic and cancerous human prostates were analyzed. The total content (units per gram of tissue) in benign hypertrophic prostate was two to four times higher than those in normal and cancerous prostates. In all the three groups, heparin-binding growth factor, growth factor adsorbed to heparin-Sepharose in the presence of 0.5 NaCl. accounted for about 80-95% of the total growth factor content. Qualitative analysis using a heparin-Sepharose column revealed two types of heparin-binding growth factor in the prostates, one eluted from the column at 1.2-1.3 M NaCl and the other at 1.5-1.8 M NaCl. The latter was the predominant type in all groups. In addition to the growth factors detected with BALB/c 3T3, a growth factor with specific action upon MC3T3-E1 mouse osteoblasts was found in prostatic cancer, but not in normal and benign hypertrophic prostates.

Aspects on reference values for tumor markers in human prostatic carcinoma

The efficiency of the tumor markers prostatic acid phosphatase (PAP), prostate-specific antigen (PSA), neopterin, and osteocalcin was tested with regard to their ability to predict cancer death within 2 years plus survival beyond 2 years in a series of patients with newly diagnosed prostate cancer. For all markers, an elevated level suggested a tumor with a worse prognosis. Moreover, the extent to which the level was increased carried additional information. The prognostic efficiency was routinely improved by selecting cutoff levels higher than the standards suggested by the radioimmunoassay (RIA) kit manufacturers. Seventy-four percent of the patients with elevated levels of neopterin were still alive after 2 years when 8 nmol/L was selected as the upper normal value compared to only 43% at 12 nmol/L. At a cut-off value of 3 micrograms/L for osteocalcin, 79% of the patients with elevated levels were still alive after 2 years compared with only 20% when 7 micrograms/L was selected. Such adjustments to higher cutoff levels could be made without increasing the number of "false-negatives." The efficiency of PAP to predict short-term prognosis was poor at the standard cutoff level of 1.9 microgram/L. Not until 20 micrograms/L was selected did the efficiency exceed 80%. PSA was highly sensitive but little specific at any of the cutoff levels tested with regard to ability to indicate prognosis.

The usefulness of prostate-specific antigen and prostatic acid phosphatase in clinical practice

A comparative study was performed on the usefulness of prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP) in control subjects (69), benign prostatic hypertrophy (BPH) patients (150), and patients with prostatic carcinoma (113) in a urology department. We establish, as others, the greater clinical sensitivity of PSA and its effectiveness as a prognostic tool in the evaluation of prostatic cancer therapy and in the early detection of residual tumor following radical prostatectomy. However, patients are admitted to our department with more severe and complicated benign prostatic pathology and urinary dysfunctions, which decreases the specificity of the PSA test to 30% (N = 2.7 ng/ml). A cutoff threshold of 50 ng/ml becomes necessary to maintain a 90% positive predictive value. The combination of PSA sensitivity (96%) and PAP specificity (95%) enabled a better definition of the high-risk subpopulation among noncancer patients and, in addition, was a help for differential diagnosis, confirmation of advanced stages of prostatic cancer, and selection of low-stage prostatic cancer candidates undergoing radical prostatectomy. Routine serum PSA measurements in the population of patients consulting a urology department will no doubt bring about a new approach to the management of prostate cancer.

Epidermal growth factor (EGF) in seminal plasma and prostatic gland: a radioreceptor assay

The binding ability of five different cells in culture to mouse epidermal growth factor (mEGF) was studied. A simple radioreceptor assay (RRA) using normal rat kidney cell (NRK-52E) as a source of EGF receptor was established. Maximal binding capacity and apparent dissociation constant of NRK-52E cell were 3.36 femtomoles of mEGF bound per 10(6) cells and 2.85 x 10(-11) M, respectively. EGF-like activity (EGF-LA) in seminal plasma and in cytosols of prostatic gland and seminal vesicle was 39.6 +/- 9.9 ng/ml, 0.67 +/- 0.10 ng/mg protein (mean +/- SE) and less than 0.2 ng/mg protein, respectively. The EGF-LA in seminal plasma was considered to be derived mainly from prostatic gland because the EGF-LA in cytosol of prostatic gland was higher than that of seminal vesicle.

Comparison of prostate-specific antigen and prostatic acid phosphatase in the management of prostatic cancer

Prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP) have been evaluated in patients with prostatic cancer. All patients, who participated in a phase III trial (n = 110), had disseminated disease and received first line endocrine treatment of either orchidectomy or a monthly injection of a depot luteinizing hormone-releasing hormone analogue (Zoladex). Serum samples were analyzed for PSA and PAP at 0, 3, 6, and 12 months and patients were clinically assessed at 6 and 12 months. At diagnosis, 72 and 97% of all patients had elevated PAP and PSA concentrations (greater than 4 ng/ml), respectively. Patients with progressive disease had significantly higher PSA and PAP levels at both assessments. A small number of patients in the "complete remission" group had both PSA and PAP levels within the normal range after 3 months of treatment. Similarly, both PSA and PAP levels steadily declined in the group of patients who had partial regression of the disease. The patients with stable disease, however, had a significant rise only in their PSA levels at the 12-month assessment. This data suggest that PSA is more sensitive than PAP in those patients who have a "slow progression" of the disease.

Is prostate-specific antigen the most useful marker for screening in prostate cancer?

Prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP) levels were determined in 241 patients attending the Department of Urology. The population consisted of 140 prostate cancer patients (34 newly diagnosed and 106 under treatment) and 101 patients with benign prostatic hypertrophy (BPH). The diagnostic values of PAP measured by enzymatic assay (EA) and by immunoenzymetric assay (IEMA) appeared to be similar. Elevated PAP (IEMA) levels were found in 10% of the patients with BPH and in 38% of the cancer patients. PSA was measured by immunoradiometric assay (IRMA) and receiver operating characteristic curves were constructed to compare the diagnostic benefits of different cutoff values. PSA (10 micrograms/L) reached a specificity of 88% and a sensitivity of 46%. With a cutoff value of 2.7 micrograms/L, the sensitivity increased to 64%, whereas the specificity fell to 58%. It is concluded that PSA is the most useful marker as a screening test.

Application of octadecylsilyl-silica in purification studies related to the nontransformed rat ventral prostate androgen receptor

We investigated the application of octadecylsilyl (ODS)-silica in studies related to characterization and purification of the nontransformed rat ventral prostate androgen receptor. The results indicated that ODS-silica successfully separates the free [3H]R1881 from the labeled [3H]R1881 transformed (4-5S) and nontransformed (8-9S) rat ventral prostate androgen receptors. Partial purification of the 8-9S receptor form was performed by the fractionation of rat cytosol using cartridges of the ODS-silica and fast-flow-rate phosphocellulose chromatography. Further purification was accomplished by differential chromatography (DEAE-cellulose and slow-flow-rate phosphocellulose chromatography). This partially purified 8-9S receptor, when analyzed on a gel permeation high-performance liquid chromatography column, resulted in a three-peak pattern of UV absorbance. One of these peaks corresponded to a 59-kD non[3H]R1881-binding protein and the remaining two corresponded to 270-kD and 190-kD[3H]R1881-binding proteins. These results demonstrate the usefulness of ODS-silica in androgen receptor studies. The association of a 59-kD nonsteroid binding protein with the nontransformed rat ventral prostate androgen receptor is discussed.

Immunohistochemical distribution of the three predominant secretory proteins in the parenchyma of hyperplastic and neoplastic prostate glands

Prostatic acid phosphate (PAP), prostate-specific antigen (PSA), and beta-microseminoprotein (beta-MSP) were regularly localized immunohistochemically to the epithelium of the acini and that of the ducts in the nodules of 24 cases of benign prostatic hyperplasia. The immunohistochemical distribution of these three prostatic-secreted proteins was also examined, with monoclonal antisera against PAP and PSA and with polyclonal antisera against PAP, PSA, and beta-MSP, in a series of 40 cases of prostatic adenocarcinomas graded according to the WHO classification. Highly differentiated (grade I) carcinomas showed a high incidence of PAP-, PSA-, and beta-MSP-immunoreactive cells. As in the normal and hyperplastic prostate parenchyma, highly differentiated (grade I) carcinomas were found to contain an almost equal number of PAP-, PSA-, and beta-MSP-immunoreactive cells. When semiquantitatively assessed, the incidence of PAP-, PSA-, and beta-MSP-immunoreactive cells was found to be lower in the moderately and poorly differentiated (grades II and III) tumors than in the highly differentiated ones; they also showed greater staining variability. Tumor cells immunoreactive with a monoclonal antiserum raised against PAP in carcinomas of grades II and III were less frequent than tumor cells immunoreactive with antisera against PSA, beta-MSP, and a polyclonal antiserum against PAP. The almost identical distribution of PSA and beta-MSP in carcinomas of grades II and III suggests that PSA and beta-MSP are not less sensitive tumor markers than PAP for the monitoring of the course and the treatment of prostatic carcinomas.

Growth factor receptors and oncogene expression in prostate cells

Specimens of benign prostatic hypertrophy (BPH) and prostate carcinoma and prostate cells in culture were assessed for their capacity to bind androgens, radioiodinated EGF, and IGF-I, and to express certain cellular protooncogenes. Prostate cell lines contained receptors for both EGF and IGF-I. Similarly, clinical samples of human diseased prostate contained receptors for both of these factors. Prostate carcinoma contained higher concentrations of EGF receptors based on DNA than did BPH, although it is accepted that BPH may not be the appropriate comparison for carcinoma. Increased EGF receptors were associated circumstantially with a decline in androgen receptors with deteriorating differentiation status and with an increase in expression of c-myc. Androgen receptor concentration correlated with increased expression of c-fos. Deteriorating differentiation status was associated with the appearance or increase in secondary sites with lower affinity for IGF-I. Whereas c-myc expression was increased in all grades of carcinoma compared to BPH, expression of c-H-ras accompanied loss of differentiation. Although those alterations are hindered by tissue heterogeneity and correlations are essentially circumstantial, they may provide clues to the progression of prostate cancer that can be validated in prostate cell lines with similar growth response capabilities.

Systematic association of PAP and PSA determinations to bone scintigraphy in prostatic cancer

Prostate-specific antigen (PSA) was compared to prostatic acid phosphatase (PAP) in patients with prostatic cancer suspected to have bone metastases. Bone scans were classified according to metastatic skeletal involvement. The sensitivity of PSA in predicting the presence of metastatic disease (68%) was better than that of PAP (53%). Specificity was 79% for PSA and 90% for PAP. Thirty-five patients had a positive PSA level and a normal scintigraphy (false-positive); 14 of them had only endoscopic prostate resection. Thirty-eight patients underwent a further exploration 3-18 months later. PSA level during disease was correlated to scintigraphy in 32 of 38 patients.