Secretion Of Prostatic Acid Phosphatase Research Articles

A New Oxopiperazin‐Based Peptidomimetic Molecule Inhibits Prostatic Acid Phosphatase Secretion and Induces Prostate Cancer Cell Apoptosis

AbstractReduced Prostatic acid Phosphatase (PAcP) secretion is associated with inhibition of the proliferation rate of prostate cancer cells. Signal peptidase 1 (SPase 1) is the main protease that cleaves the signal peptide of secretory proteins and allows their secretion. Thus, we hypothesised that inhibition of SPase 1 might lead to an antiproliferative effect in prostate cancer cells. Using homology computer modelling, we created a human SPase 1 model. With this model we designed and synthesised four novel (S)‐3‐(4‐aminobutyl)piperazin‐2‐one‐based peptidomimetics. The in vitro cytotoxic activity of these compounds was evaluated in the Lymph Node Carcinoma of the Prostate (LNCaP) cancer cell line. Indeed, (S)‐(3‐(2‐(4‐(((benzyloxy)carbonyl)amino)butyl)‐4‐(3‐methoxy‐3‐oxopropyl)‐3‐oxopiperazin‐1‐yl)propyl)boronic acid, compound 8) reduced PAcP secretion, as well as exhibited significant cytotoxic effect in LNAcP cells. As reported in this study, an antiprostate cancer drug development approach, which is based on inhibiting PAcP secretion, is innovative and it might serve as source for developing novel antiprostate cancer drugs.

Functional upregulation of the H2S/Cav3.2 channel pathway accelerates secretory function in neuroendocrine-differentiated human prostate cancer cells

Neuroendocrine-differentiated prostate cancer cells may contribute to androgen-independent proliferation of surrounding cells through Ca2+-dependent secretion of mitogenic factors. Human prostate cancer LNCaP cells, when neuroendocrine-differentiated, overexpress Cav3.2 T-type Ca2+ channels that contribute to Ca2+-dependent secretion. Given evidence for the acceleration of Cav3.2 activity by hydrogen sulfide (H2S), we examined the roles of the H2S/Cav3.2 pathway and then analyzed the molecular mechanisms of the Cav3.2 overexpression in neuroendocrine-differentiated LNCaP cells. LNCaP cells were differentiated by dibutyryl cyclic AMP. Protein levels and T-type Ca2+ channel-dependent currents (T-currents) were measured by immunoblotting and whole-cell pacth-clamp technique, respectively. Spontaneous release of prostatic acid phosphatase (PAP) was monitored to evaluate secretory function. The differentiated LNCaP cells exhibited neurite outgrowth, androgen-independent proliferation and upregulation of mitogenic factors, and also showed elevation of Cav3.2 expression or T-currents. Expression of cystathionine-γ-lyase (CSE) and cystathionine-β-synthase (CBS), H2S-forming enzymes, and spontaneous secretion of PAP increased following the differentiation. The augmented T-currents were enhanced by H2S donors and suppressed by inhibitors of CSE, but not CBS. The PAP secretion was reduced by inhibition of CSE or T-type Ca2+ channels. During differentiation, Egr-1 and REST, positive and negative transcriptional regulators for Cav3.2, were upregulated and downregulated, respectively, and Egr-1 knockdown prevented the Cav3.2 overexpression. Our data suggest that, in neuroendocrine-differentiated LNCaP cells, H2S formed by the upregulated CSE promotes the activity of the upregulated Cav3.2, leading to the elevated secretory functions. The overexpression of Cav3.2 appears to involve upregulation of Egr-1 and downregulation of REST.

Abstract LB-375: Development of new compounds specifically targeting prostate cancer bone metastases

Abstract Introduction: Bone metastases are a major cause of morbidity for men with prostate cancer (PCa). Although PCa cells produce osteoblastic metastases, there is an initial and ongoing osteoclast (OC)-mediated osteolytic phase that is essential for PCa bone metastases. OC-mediated bone resorption is dependent upon OC secretion of bone acid phosphatase. PCa cells in bone secrete high levels of prostatic acid phosphatase (PAP) which differs from BAP in that PAP enzymatic activity is inhibited by tartrate and glyceric acid, whereas BAP is tartrate-resistant. Hypothesis: PAP secreted by human PCa cells in bone acts similarly to OC-derived bone acid phosphatase to degrade bone matrix and enhance PCa bone-targeting and growth in bone. We developed new compounds consisting of glyceric acid or tartrate (known PAP inhibitors) conjugated to a bisphosphonate to inhibit PCa bone metastases. Methods: PCa bone metastases derived from 7 patients were immunostained for androgen receptor (AR), prostate specific antigen (PSA) and PAP expression. The VCaP human PCa cell line derived from a vertebral metastases was inoculated intratibially into SCID mice (n=8) and bone lesions immunostained for AR, PSA, and PAP. Co-cultures of MC3T3 osteoblasts and VCaP cells were treated with tartrate and the effects on cell number, PAP and bone alkaline phosphatase (ALP) secretion measured by ELISA. Glyceric Acid and Tartaric acid were then conjugated with alendronate and the effects of these new conjugates on PAP enzymatic activity were compared to alendronate alone and tartrate alone. Results: Human PCa bone lesions (7/7) had strongly positive expression of PAP, with little AR or PSA expression. 8/8 SCID mice inoculated with VCaP cells intratibially developed osteoblastic VCaP lesions and these similarly had high PAP expression and no PSA expression. Tartrate addition to co-cultures of VCaP and MC3T3 osteoblasts reduced MC3T3 cell numbers and ALP secretion. In vitro testing of the conjugates revealed that the glyceric acid-alendronate conjugate inhibited PAP enzymatic activity but the tartrate-alendronate conjugate and alendronate alone had no significant inhibitory activity. Discussion: We have evidence that PAP secretion by PCa cells enhances their bone metastatic ability. We have developed new bone-targeting agents that consist of alendronate conjugated to PAP-inhibitory small molecules for further development as oral agents to prevent and treat PCa bone metastases. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-375.

Protein kinase C pathway is involved in regulating the secretion of prostatic acid phosphatase in human prostate cancer cells.

The stimulated secretion of prostatic acid phosphatase (PAcP) has been known to be a hallmark of androgen action on human prostate epithelial cells for the last five decades. The molecular mechanism of androgen action on PAcP secretion, however, has remained mostly unknown. We investigated the molecular mechanism that promotes PAcP secretion in LNCaP human prostate carcinoma cells which express PAcP and are androgen-responsive. Treatment with 12-o-tetradecanoyl phorbol-13-acetate (TPA), a protein kinase C (PKC) activator, resulted in an increased secretion of PAcP in a dose- and time-dependent fashion. 4Alpha-phorbol, a biologically inactive isomer of TPA, had no effect. This TPA stimulation of PAcP secretion was observed 2 h after exposure, while TPA did not have a significant effect on the mRNA level even with a 6 h treatment. A23187 calcium ionophore, known to mobilize cellular calcium which is a co-factor of PKC, also activated PAcP secretion. This TPA stimulation of PAcP secretion was more potent than the conventional stimulating agent 5alpha-dihydrotestosterone (DHT) at the same concentration of 50 nM. Furthermore, the action of TPA and DHT on PAcP secretion was blocked by five different PKC inhibitors. Results also showed that DHT, as well as TPA, could rapidly modulate PKC activity. Therefore, PKC can regulate PAcP secretion, and may also be involved in DHT action on PAcP secretion.

Physical activity releases prostate-specific antigen (PSA) from the prostate gland into blood and increases serum PSA concentrations

Determination of prostate-specific antigen (PSA) is an established tool in detecting prostate cancer. However, the effect of physical activity on the PSA concentration in serum is controversial. We measured serum concentrations of PSA and prostatic acid phosphatase (PAP) in 301 healthy outpatients before and after they performed standardized exercise. Immediately after 15 min of exercise on a bicycle ergometer, their serum PSA concentrations increased by as much as threefold. The increase was age dependent and correlated to the PSA concentration before exercise. This increase was evident in both the free and complexed fractions of PSA. The amount of PSA secreted into blood depends on the volume of the prostate, whereas productivity of the prostate epithelium remains constant or increases slightly with age. We present cutoff values for clinical use. PAP was also increased, but to a lesser extent. The PSA and PAP secretion mechanisms differ. Our data suggest that extensive physical activity should be avoided before blood sampling for diagnostic purposes and, in case of an increase, the PSA concentration should be controlled after an exercise test.

Characterization of ALVA-41 cells, a new human prostatic cancer cell line

The ALVA-41 cell line was derived from a bony metastasis from a human prostatic carcinoma. The line has a number of distinct, advantageous properties that should make it useful as a tool for the study of prostate cancer. It grows rapidly and is easy to work with. It has receptors for androgens and glucocorticoids but not for estrogens. Its growth is enhanced by physiological concentrations of dihydrotosterone. It does not secrete prostate specific antigen, but does not secrete prostatic acid phosphatase. Further, the secretion of prostatic acid phosphatase is enhanced by dihydrotesterone.

Regulation of Prostatic Acid Phosphatase Expression and Secretion by Androgen in LNCaP Human Prostate Carcinoma Cells

The expression and the secretion of human prostatic acid phosphatase (PAcP), a differentiation antigen which is the major acid phosphatase in prostate epithelial cells, are thought to be regulated by an androgen. We investigated this regulatory mechanism at the post-transcriptional level in LNCaP human prostate carcinoma cells using a cDNA clone for the secretory form of PAcP. 5α-Dihydrotestosterone (DHT, an active form of endogenous androgen) stimulated the secretion of PAcP from cells grown in a steroid-reduced medium and in a defined serum-free medium, respectively. The secreted PAcP activity was increased following a DHT dose in a dose-dependent fashion at concentrations of up to 1 μM. Further, the stimulation of PAcP secretion occurred following the period of exposure to DHT. During a 5-day treatment period, with 10 nM of DHT in the steroid-reduced medium, the secretion of PAcP was stimulated approximately 150% over that from control cells. Nevertheless, PAcP was secreted from cells grown in the absence of added DHT. First, the androgen dependency of PAcP expression was examined. The expression and the secretion of PAcP were observed in cells that were grown in a defined serum-free medium and grown in a steroid-reduced medium, in the absence of DHT. The increased secretion by DHT was further demonstrated to be in part due to an increase in PAcP mRNA level, as evidenced by Northern blot analysis. PAcP mRNA levels were elevated approximately 2-fold and corresponded to an increase of approximately 2.5-fold in the secreted level of newly synthesized 35S-PAcP. Then, the effect of DHT on the secretory process was investigated. Results of pulse-chase labeling experiments indicated that the secretory rate of PAcP was stimulated by about 50% on average by DHT. In conclusion, our data demonstrated that, in LNCaP cells, the expression and the secretion of PAcP regulated by androgen are apparently hormone-responsive processes. Further, DHT stimulation of PAcP secretion operates within at least two levels: increased PAcP mRNA and stimulation of the secretory pathway.

Effect of culture conditions on androgen sensitivity of the human prostatic cancer cell line LNCaP.

Several effects of androgens on LNCaP-FGC prostate tumor cells showed a biphasic pattern. Stimulation of growth and inhibition of secretion of prostatic acid phosphatase (PAP) was observed at low androgen concentrations (below 1 nM of the synthetic androgen R1881), and inhibition of growth and stimulation of PAP secretion was observed at higher concentrations. In contrast, prostate specific antigen (PSA) secretion did not show this biphasic response pattern. Comparable effects were found for two sublines of the LNCaP-FGC cells: an early (passage 20, androgen-dependent) and relatively late (passage 70, androgen-sensitive) passage of the cells. Culturing of both sublines in the presence of a high concentration of androgens (10 nM R1881) resulted initially in a decrease in growth rate, but the cells started to proliferate within 3 weeks. These cells became less sensitive to androgens, lost their biphasic response pattern, and showed reduced androgen receptor levels. Three weeks after removal of the excess of androgens, the passage 70 cells regained a biphasic growth response to androgens. Culture in medium without steroids but with EGF resulted in a decrease of both androgen sensitivity and androgen receptor level. In conclusion, rapid changes of the androgen sensitivity and receptor level of the LNCaP cells occurred under the influence of culture conditions. These changes were partly reversible and, therefore, were most likely due to adaptation of the cells.

An investigation into the origins of a copious vaginal discharge during intercourse: “enough to wet the bed”‐that “is not urine”

A case study of large‐volume vaginal discharge during intercourse originally prepared in 1979, is described, as is the course of investigation into its origin. It is argued that this “wetting of the bed” is not a pathological significance but is within the normal range and variation of the physiological function of the paraurethral glands of Skene. A 1982 addendum discusses developments in this field of sexual research, including the rediscovery of female ejaculation; 2 decades dominated by the “paradigm of cliterocentricity” and a recent shift back to the vagina, specifically the urethro‐vaginal body, in female sexual function. A 1983 addendum reports on an immunohistochemical demonstration of the homology between the female urethral glands and the male prostate. Evidence for the secretion of prostatic acid phosphatase by the female glands suggests an ejaculatory function equivalent to that of the male though without the gonadal, “seminal” component. Further investigations of female ejaculation are discussed.