Yasuhiro Shibata

Changes in the endocrine environment of the human prostate transition zone with aging: simultaneous quantitative analysis of prostatic sex steroids and comparison with human prostatic histological composition.

It is well‐known that the incidence of benign prostatic hyperplasia (BPH) increases with aging. The age‐dependent changes in the ratio of serum sex steroid concentrations may play a role in BPH development. To clarify the relationship between the prostatic tissue concentrations of these steroids and age, we established a precise method of simultaneous quantitative analysis for prostatic sex steroids and used this method to investigate the tissue concentrations of three major sex steroids (testosterone, dihydrotestosterone, and estradiol) in the human prostate.

NK cell-mediated anti-tumor immune response to human prostate cancer cell, PC-3: immunogene therapy using a highly secretable form of interleukin-15 gene transfer

Interleukin (IL)‐15 is a pleiotropic cytokine that is important forinnate and adaptive immune cell homeostasis. The expression of IL‐15protein is controlled by posttranscriptional mechanisms. Here, weconstructed a human IL‐15 expression vector consisting of the humanIL‐2 signal peptide, the human IL‐15 mature peptide‐coding sequences,and an out‐of‐frame human growth hormone gene. Human prostate cancercells, PC‐3, transfected with this highly secretable form of the IL‐15gene, successfully secreted abundant bioactive IL‐15 protein. In nudemice, the growth of PC‐3 cells producing IL‐15 was remarkably retarded.NK cell‐depletion using anti‐asialo GM1 antibody restoredtumorigenicity. Histologically, tumors derived from IL‐15‐producingPC‐3 cells contained necrotic areas with high apoptotic index.Splenocytes incubated with supernatant of transfectants killed targetPC‐3 cells and expressed a significantly high level of mIFN‐γ mRNA.These observations suggest that NK cell‐mediated, anti‐tumor effects ofIL‐15 could provide a potential rationale for gene therapy of prostatecancer.

Diagnostic significance of [−2]pro-PSA and prostate dimension-adjusted PSA-related indices in men with total PSA in the 2.0–10.0 ng/mL range

PurposeOne of the most important issues to address when developing an optimal screening system for prostate cancer is investigating appropriate biopsy indications following serum prostate-specific antigen (PSA) measurements in order to maintain high sensitivity and avoid unnecessary biopsy.MethodsBetween April 2004 and December 2007, 239 consecutive men with total PSA levels of 2.0–10.0xa0ng/mL underwent measurements of PSA, free PSA, and [−2]pro-PSA. We assessed the significance of laboratory-based PSA-related indices including free PSA/total PSA (%f-PSA), p2PSA/free PSA (%p2PSA), p2PSA/%f-PSA, Prostate Health Index (phi, an index combining PSA, free PSA, and p2PSA), total prostate volume (TPV)-adjusted PSA-related indices, including PSA density, %p2PSA density, p2PSA/%f-PSA density, and phi density, and transition zone (TZ) prostate volume-adjusted PSA-related indices such as PSA TZ density (PSATZD), %p2PSA TZD, p2PSA/%fPSA TZD, and phi TZD.ResultsThe positive biopsy rate was 22.2xa0%. When sensitivity was fixed at 95xa0%, unnecessary biopsies could be avoided in 28xa0% of men when phi was used as a biopsy indication. In cases where total and transition zone prostate volumes were available, the use of %p2PSA density, phi density, p2PSA/%f-PSA TZD, and phi TZD resulted in the avoidance of 48, 47, 54, and 54xa0% of unnecessary biopsies, respectively, while maintaining a high sensitivity of 90xa0%.ConclusionsAt 90 and 95xa0% sensitivity, laboratory-based indices containing p2PSA, particularly phi, showed significantly greater specificity for prostate cancer as compared with %f-PSA. The diagnostic accuracy of prostate volume-adjusted p2PSA-related indices could be excellent, particularly the transition zone volume-adjusted indices at fixed sensitivities of 95 and 90xa0%.

Effect of castration monotherapy on the levels of adrenal androgens in cancerous prostatic tissues.

The mechanism accounting for the development of castration-resistant prostate cancer (CRPC) remains unclear. Studies in CRPC tissues suggest that, after androgen deprivation therapy (ADT), the adrenal androgens may be an important source of testosterone (T) and 5-alpha dihydrotestosterone (DHT) in CRPC tissues. To clarify the role of adrenal androgens in the prostatic tissues (prostatic tissue adrenal androgens) during ADT, we developed a high sensitive and specific quantification method for the levels of androgens in prostatic tissue using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Human prostatic tissues were purified using mixed-mode reversed-phase, strong anion exchange Oasis cartridges (Oasis MAX). Analysis of steroids was performed using LC-MS/MS after picolinic acid derivatization. The validation tests showed that our method of quantitative analysis was precise and sensitive enough for the quantification of dehydroepiandrosterone (DHEA), androstenedione, androstenediol, T, and DHT in the prostatic tissue. The levels of adrenal androgens in prostate cancer tissues after ADT were similar to those in untreated PCa. Especially, DHEA was the most existing androgen precursor in PCa tissues after ADT. The levels of DHEA were high in PCa tissues, irrespective of ADT. We assumed that DHEA played a significant role in the synthesis of T and DHT in PCa tissues after ADT.

New quantification method for estradiol in the prostatic tissues of benign prostatic hyperplasia using liquid chromatography–tandem mass spectrometry

Estrogen is suspected to play a role in the pathogenesis of benign prostatic hyperplasia (BPH) and prostate cancer. To clarify the role of estradiol (E2) in the prostatic tissues (prostatic tissue E2) during the development of prostatic disorders, we developed a new sensitive and specific quantification method for prostatic tissue E2 using liquid chromatography-tandem mass spectrometry (LC-MS/MS). For the solid-phase extraction, E2 was purified by anion-exchange through an Oasis MAX cartridge. In addition, after the formation of 3-pentaflurobenzyl-17beta-pyridinium-estradiol derivative (E2-PFBPY), E2-PFBPY was purified by cation-exchange through an Oasis WCX cartridge. These processes in the LC-MS/MS method improved the specificity and sensitivity for prostatic tissue E2 measurement, compared to the radioimmunoassay (RIA) method. The validation tests showed that intra-day and inter-day precisions were both within +/-15% (except for 15.5% of the inter-day precision of the lowest concentration), with the accuracy ranging from 88 to 110%. The quantification limit of this assay was 0.15pg/tube in our method, which was 80-fold more sensitive than that of the RIA method. With the use of our present method, the median E2 levels in the prostatic tissues in patients with BPH (n=20, median age: 71 years) were 12.0pg/g tissue (95% confidence interval=9.1-22.6pg/g tissue). Furthermore, the E2 levels increased significantly with aging. These results showed that our present method would be useful for elucidating the role of prostatic tissue E2 in the development of prostatic disorders with a small amount of tissue samples.

COMPARISON OF HISTOLOGICAL COMPOSITIONS AND APOPTOSIS IN CANINE SPONTANEOUS BENIGN PROSTATIC HYPERPLASIA TREATED WITH ANDROGEN SUPPRESSIVE AGENTS CHLORMADINONE ACETATE AND FINASTERIDE

PURPOSEnChlormadinone acetate and finasteride are androgen suppressive agents clinically used for benign prostatic hyperplasia but their mechanism for inducing prostatic atrophy differs. We investigated the effect of these androgen suppressive agents on prostatic histology and apoptosis using the spontaneous canine benign prostatic hyperplasia model.nnnMATERIALS AND METHODSnAnimals were treated with oral chlormadinone acetate or finasteride for 25 weeks. The prostatic volumes were analyzed every 5 weeks. Prostatic androgen and estrogen concentrations, histological composition and apoptosis were determined at the end of treatment. Apoptosis was measured by in situ labeling of 3 hydroxy ends of the DNA breaks using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling method.nnnRESULTSnThere was a similar volume reduction effect with 0.3 mg./kg. chlormadinone acetate daily and 1 mg./kg. finasteride daily. Chlormadinone acetate decreased testosterone and dihydrotestosterone but finasteride decreased only dihydrotestosterone in the prostate gland. The concentration ratio of estradiol-to-total androgen in the prostate was significantly increased in finasteride treated canines. Chlormadinone acetate and finasteride decreased the epithelial and stromal components. The extent of apoptosis observed in the prostate was significantly higher in the chlormadinone acetate group compared to that of the control and finasteride groups.nnnCONCLUSIONSnAlthough a similar effect of chlormadinone acetate and finasteride was observed in the induction of prostatic regression and composition of the histological components, the sustained increase in apoptosis was observed only in chlormadinone acetate treated canines. We suggest that different intraprostatic endocrine environments created by chlormadinone acetate or finasteride, which have different intraprostatic testosterone levels and estradiol-to-androgen ratios, may be responsible for the different outcomes in the extent of apoptosis.

Rapamycin enhances docetaxel-induced cytotoxicity in a androgen-independent prostate cancer xenograft model by survivin downregulation.

BACKGROUNDnDocetaxel is a first-line treatment choice in castration-resistant prostate cancer (CRPC). However, the management of CRPC remains an important challenge in oncology. There have been many reports on the effects of rapamycin, which is an inhibitor of the mammalian target of rapamycin (mTOR), in the treatment of carcinogenesis. We assessed the cytotoxic effects of the combination treatment of docetaxel and rapamycin in prostate cancer cells. Furthermore, we examined the relationship between these treatments and survivin, which is a member of the inhibitory apoptosis family.nnnMETHODSnProstate cancer cells were cultured and treated with docetaxel and rapamycin. The effects on proliferation were evaluated with the MTS assay. In addition, we evaluated the effect on proliferation of the combination treatment induced knockdown of survivin expression by small interfering RNA transfection and docetaxel. Protein expression levels were assayed using western blotting. PC3 cells and xenograft growth in nude mice were used to evaluate the in vivo efficacy of docetaxel and its combination with rapamycin.nnnRESULTSnIn vitro and in vivo, the combination of rapamycin with docetaxel resulted in a greater inhibition of proliferation than treatment with rapamycin or docetaxel alone. In addition, in vitro and in vivo, rapamycin decreased basal surviving levels, and cotreatment with docetaxel further decreased these levels. Transfection siRNA against survivin enhanced the cytotoxicity of docetaxel in PC3 cells.nnnCONCLUSIONnThe rapamycin-dependent enhancement of the cytotoxic effects of docetaxel was associated with the downregulation of survivin expression. Our results suggest that the combination of docetaxel and rapamycin is a candidate for the improved treatment of advanced prostate cancer.

An innovative LC-MS/MS-based method for determining CYP 17 and CYP 19 activity in the adipose tissue of pre- and postmenopausal and ovariectomized women using 13C-labeled steroid substrates.

CONTEXTnDoes adipose tissue produce steroid hormones like an endocrine organ?nnnOBJECTnTo clarify whether adipose tissue produces sex steroid hormone like an endocrine organ, we estimated several key steroid hormone levels, as well as CYP17 and CYP19 activity, in ovariectomized, pre- and postmenopausal women by liquid chromatography-tandem mass spectrometry (LC-MS/MS).nnnSUBJECTS AND METHODSnThe subjects were 19 premenopausal (n = 12), postmenopausal (n = 4), and ovariectomized women (n = 3) aged 27-68 years. Serum, visceral adipose and sc adipose samples were taken from these subjects and stored at -70°C. The levels of cortisol, cortisone, progesterone (Prog), androstenedione, dehydroepiandrosterone, estrone, estradiol (E2), and T in serum and adipose tissue were estimated simultaneously by LC-MS/MS. CYP17 and CYP19 activity in tissues were assayed with the use of (13)C-labeled steroid precursors and LC-MS/MS-based estimation of the metabolites.nnnRESULTSnE2 and Prog levels in the sera of postmenopausal or ovariectomized women were less than 10% of those in premenopausal women. No marked variations were seen in other hormones. Estrone, androstenedione, dehydroepiandrosterone, and Prog levels in the visceral and sc tissues of postmenopausal and ovariectomized women were 9-60 times higher than those in serum, whereas E2 and T levels were 3- to 7-fold higher than those in serum, and cortisol and cortisone levels were 20% of those found for serum. CYP17 in adipose tissue was found to have 17-hydroxylase and 20,17-lyase activity, with each catalytic activity being essentially equal. Therefore, CYP17 in adipose tissue is of the testicular/ovarian type but not adrenal type, which has 17-hydroxylase activity dominant. The presence of CYP19 activity in adipose tissue was approximately 3% of CYP17.nnnCONCLUSIONnOur findings suggest that adipose tissue acts as an endocrine organ, with CYP17 and CYP19 activity playing an essential role in sex steroid hormone biosynthesis.

Luteinizing hormone (LH)-releasing hormone agonist reduces serum adrenal androgen levels in prostate cancer patients: implications for the effect of LH on the adrenal glands.

Recently, adrenal androgens have been targeted as key hormones for the development of castration-resistant prostate cancer therapeutics. Although circulating adrenal androgens originate mainly from the adrenal glands, the testes also supply about 10%. Although widely used in androgen deprivation medical castration therapy, the effect of luteinizing hormone-releasing hormone (LH-RH) agonist on adrenal androgens has not been fully studied. In this study, changes in testicular and adrenal androgen levels were measured and compared to adrenocorticotropic hormone levels. To assess the possible role of LH in the adrenal glands, immunohistochemical studies of the LH receptor in normal adrenal glands were performed. Forty-seven patients with localized or locally progressive prostate cancer were treated with LH-RH agonist with radiotherapy. Six months after initiation of treatment, testosterone, dihydrotestosterone, and estradiol levels were decreased by 90%-95%, and dehydroepiandrosterone-sulfate, dehydroepiandrosterone, and androstenedione levels were significantly decreased by 26%-40%. The suppressive effect of LH-RH agonist at 12 months was maintained. Adrenocorticotropic hormone levels showed an increasing trend at 6 months and a significant increase at 12 months. LH receptors were positively stained in the cortex cells of the reticular layer of the adrenal glands. The long-term LH-RH agonist treatment reduced adrenal-originated adrenal androgens. LH receptors in the adrenal cortex cells of the reticular layer might account for the underlying mechanism of reduced adrenal androgens.

Survivin is associated with cell proliferation and has a role in 1a,25-dihydroxyvitamin D3 induced cell growth inhibition in prostate cancer.

PURPOSEnProstate cancer cell proliferation is inhibited by 1a,25-dihydroxyvitamin D(3). Survivin is a member of the inhibitors of apoptosis protein family. Several studies indicate that survivin down-regulation sensitizes human tumor cells of different histological origins to conventional chemotherapeutic drugs. We assessed the effect of survivin gene expression on the proliferation of prostate cancer cells in vitro and in vivo. We also examined the antitumor sensitization effect of survivin inhibition in 1a,25-dihydroxyvitamin D(3) treatment for prostate cancer cells.nnnMATERIALS AND METHODSnWe knocked down gene expression levels of survivin using siRNA against survivin in vitro and in vivo. We then assessed survivin expression in 1a,25-dihydroxyvitamin D(3) treatment and examined the antitumor sensitization effect of survivin inhibition using siRNA in 1a,25-dihydroxyvitamin D(3) treatment of hormone resistant prostate cancer cells.nnnRESULTSnIn vitro and in vivo siRNA against survivin significantly inhibited cell and tumor growth compared with control siRNA. In LNCaP and PC3 cells 1a,25-dihydroxyvitamin D(3) decreased survivin gene expression and inhibited cell proliferation. However, survivin gene expression and cell proliferation were not inhibited in DU145 cells but after siRNA transfection against survivin DU145 cell proliferation was inhibited by 1a,25-dihydroxyvitamin D(3).nnnCONCLUSIONSnFindings suggest that survivin has a significant association with prostate cancer cell proliferation and an essential role in 1a,25-dihydroxyvitamin D(3) induced prostate cancer cell growth inhibition. It seems that the eliminating survivin in 1a,25-dihydroxyvitamin D(3) therapy for hormone refractory prostate cancer is a potential therapeutic option.