Carcinoma of the prostate. Hormonal therapy

No effect of unacylated ghrelin administration on subcutaneous PC3 xenograft growth or metabolic parameters in a Rag1-/- mouse model of metabolic dysfunction

Ghrelin is a peptide hormone which, when acylated, regulates appetite, energy balance and a range of other biological processes. Ghrelin predominately circulates in its unacylated form (unacylated ghrelin; UAG). UAG has a number of functions independent of acylated ghrelin, including modulation of metabolic parameters and cancer progression. UAG has also been postulated to antagonise some of the metabolic effects of acyl-ghrelin, including its effects on glucose and insulin regulation. In this study, Rag1-/- mice with high-fat diet-induced obesity and hyperinsulinaemia were subcutaneously implanted with PC3 prostate cancer xenografts to investigate the effect of UAG treatment on metabolic parameters and xenograft growth. Daily intraperitoneal injection of 100 μg/kg UAG had no effect on xenograft tumour growth in mice fed normal rodent chow or 23% high-fat diet. UAG significantly improved glucose tolerance in host Rag1-/- mice on a high-fat diet, but did not significantly improve other metabolic parameters. We propose that UAG is not likely to be an effective treatment for prostate cancer, with or without associated metabolic syndrome.

Castration-Resistant Prostate Cancer: Sequencing Oral and Infusion Agents

PURPOSE OF REVIEW

To update treatment options and considerations for castration-resistant prostate cancer with specific attention to sequencing of agents based on available evidence and treatment rationale.

RECENT FINDINGS

The newest research developments over the last several years include multicenter studies that address the sequencing of therapies to improve the treatment of metastatic castration-resistant prostate cancer. Chemotherapy agents, as well as androgen receptor antagonists, are evolving, and there are new tests available to define which patients are more likely to benefit. In addition, there have been some additional trials looking into the safety and efficacy of combination treatment and new therapies. There are multiple factors that should be considered to determine the sequence and/or combinations of therapies for metastatic castration-resistant prostate cancer that can improve quality of life and survival. Promising novel agents in combination with personalized medicine will likely continue to improve treatment of these patients.

Diethylstilboestrol for the treatment of prostate cancer: past, present and future

The aim of this review was to discuss the most recent data from current trials of diethylstilboestrol (DES) to identify its present role in advanced prostate cancer treatment as new hormonal therapies emerge. The most relevant clinical studies using DES in castration-refractory prostate cancer (CRPC) were identified from the literature. The safety, efficacy, outcomes and mechanisms of action are summarized. In the age of chemotherapy this review highlights the efficacy of oestrogen therapy in CRPC. The optimal point in the therapeutic pathway at which DES should be prescribed remains to be established.

Hinokitiol, a metal chelator derived from natural plants, suppresses cell growth and disrupts androgen receptor signaling in prostate carcinoma cell lines

Hinokitiol (beta-thujaplicin), a troplone-related compound found in the heartwood of cupressaceous plants, strongly inhibits the proliferation of a broad range of tumor cell lines. This is the first report to demonstrate that hinokitiol, a metal chelator derived from natural plants, suppresses cell growth and disrupts AR signaling in prostate carcinoma cell lines. Our present studies indicate that hinokitiol suppresses androgen/AR-mediated cell growth and androgen-stimulated DNA synthesis by [(3)H]thymidine incorporation in a dose- and time-dependent manner. Hinokitiol simultaneously suppresses the intracellular and secreted PSA levels, a marker for the progression of prostate cancer. Hinokitiol significantly represses the AR mRNA and protein expression in a dose- and time-dependent manner. Additionally, the ligand-binding assay shows that hinokitiol blocks binding of the synthetic androgen [(3)H]R1881 to AR in LNCaP cells. These findings collectively suggest that hinokitiol is potentially effective against prostate cancer in vitro, and thus it might become a novel chemopreventive or chemotherapeutic agent for prostate cancer.

Prostate androgen-regulated gene: a novel potential target for androgen-independent prostate cancer therapy

AIM

To investigate the involvement of the prostate androgen-regulated (PAR) gene in the androgen receptor (AR) signaling pathway and the malignant phenotype of androgen-independent prostate cancer (PCa) cells.

METHODS

The difference in PAR expression between LNCaP and PC3 cells was detected by reverse transcription-polymerase chain reaction (RT-PCR). Androgen and anti-androgen effects on PAR expression were evaluated by RT-PCR in LNCaP, PC3 cells and PC3 cells stably transfected with vector containing wild-type AR. To determine the importance of PAR in the malignant proliferation of androgen-independent PCa cells, we used small interfering RNA (siRNA) transfection to knock down the expression of the gene in PC3 cells. The changes in the malignant phenotype of PCa cells after transfection were analyzed by cell count, colony formation in soft agar and flow cytometry.

RESULTS

PAR expression was 3-fold higher in PC3 cells than that in LNCaP cells. Dihydrotestosterone (DHT) regulated PAR mRNA expression in LNCaP cells and the effect was inhibited by the AR antagonist, flutamide. By contrast, DHT did not affect PAR expression in PC3 cells. The reintroduction of AR into PC3 cells by stable transfection restored the androgen effect on PAR upregulation. After the knockdown of the PAR gene by siRNA, PC3 cells exhibited a reversal of the malignant phenotype.

CONCLUSION

Because of the possibility that PAR is downstream from the AR, and because of its contribution to malignant proliferation in androgen-independent PCa cells, the gene could be a potential therapeutic target for androgen-independent PCa with AR signaling pathway alteration.

Protocadherin-PC promotes androgen-independent prostate cancer cell growth

BACKGROUND

Protocadherin-PC (PCDH-PC) expression is upregulated in apoptosis-resistant sublines of the LNCaP human prostate cancer (CaP) cell line. Here, we assess the role of PCDH-PC in CaP cells and its mRNA expression in human prostate tissues.

METHODS

LNCaP cells transfected with PCDH-PC were tested for their ability to grow in vitro and in vivo in androgen-deprived conditions. PCDH-PC mRNA expression was evaluated by semi-quantitative RT-PCR and by in situ hybridization.

RESULTS

PCDH-PC expression induced Wnt signaling in CaP cells and permitted androgen-independent growth of hormone-sensitive CaP cells. Expression of PCDH-PC-homologous transcripts was low and restricted to some epithelial cells in normal tissue and to CaP cells in tumors. However, hormone-resistant CaP cells expressed significantly higher levels of PCDH-PC-related mRNA.

CONCLUSIONS

Our findings suggest a novel mechanism for the progression of CaP involving expression of PCDH-PC. This novel protocadherin induces Wnt signaling, promotes malignant behavior and hormone-resistance of CaP cells.

Pharmacological characterization of urinary bladder smooth muscle contractility following partial bladder outlet obstruction in pigs

Partial bladder outlet obstruction of the pig is considered as a valuable preclinical model for evaluating the profile of compounds for the treatment of bladder overactivity. In this study, we characterized the pharmacological properties of isolated bladder smooth muscle from pigs following partial outlet obstruction and its sensitivity to potassium channel openers. Bladder strips from obstructed animals showed significantly lower maximal efficacy (E(max)) and sensitivity to stimulation by ATP and carbachol, but not to those evoked by serotonin, compared to age-matched controls. Tissue strips from obstructed animals also showed a 2.5-fold increase in the potency and significantly reduced maximum response following K+ depolarization. With respect to spontaneous activity, bladder strips from control strips demonstrated little spontaneous phasic activity at all preloads examined. In contrast, bladder strips from obstructed animals showed large preload-dependent increases in spontaneous phasic activity at preload values of 16-32 g. The potencies of K(ATP) channel openers to relax carbachol-evoked contractions showed a good 1:1 correlation (r(2)=0.90) between obstructed and control bladder strips. These studies demonstrate that obstructed pig bladders show enhanced spontaneous phasic activity especially at elevated preloads, which may underlie unstable myogenic bladder contractions reported in cystometrographic measurements in vivo. The impaired responses to electrical field stimulation could be attributed to reduced efficacies and/or lower sensitivities of muscarinic and purinergic signaling pathways. K(ATP) channel sensitivities remain essentially unimpaired in the obstructed bladder and could be effectively modulated by openers with potential for the treatment of overactive bladder secondary to outlet obstruction.

Profiling Genetic Variation along the Androgen Biosynthesis and Metabolism Pathways Implicates Several Single Nucleotide Polymorphisms and Their Combinations as Prostate Cancer Risk Factors

Several candidate genes along androgen pathway have been suggested to affect prostate cancer risk but no single gene seems to be overwhelmingly important for a large fraction of the patients. In this study, we first screened for variants in candidate genes and then chose to explore the association between 18 variants and prostate cancer risk by genotyping DNA samples from unselected (n = 847) and familial (n = 121) prostate cancer patients and population controls (n = 923). We identified a novel single nucleotide polymorphism (SNP) in the CYP19A1 gene, T201M, with a mild significant association with prostate cancer [odds ratio (OR), 2.04; 95% confidence interval (95% CI), 1.03-4.03; P = 0.04]. Stratified analysis revealed that this risk was most apparent in patients with organ-confined (T(1)-T(2)) and low-grade (WHO grade 1) tumors (OR, 5.42; 95% CI, 2.33-12.6; P < 0.0001). In contrast, CYP17A1 -34T>C alteration was associated with moderate to poorly differentiated (WHO grade 2-3) organ-confined disease (OR, 1.42; 95% CI, 1.09-1.83; P = 0.007). We also tested a multigenic model of prostate cancer risk by calculating the joint effect of CYP19A1 T201M with five other common SNPs. Individuals carrying both the CYP19A1 and KLK3 -252A>G variant alleles had a significantly increased risk for prostate cancer (OR, 2.87; 95% CI, 1.10-7.49; P = 0.03). In conclusion, our results suggest that several SNPs along the androgen pathway, especially in CYP19A1 and CYP17A1, may influence prostate cancer development and progression. These genes may have different contributions to distinct clinical subsets as well as combinatorial effects in others illustrating that profiling and joint analysis of several genes along each pathway may be needed to understand genetic contributions to prostate cancer etiology.

Oncogenic action of phospholipase A2 in prostate cancer

Mortality from prostate cancer is a result of progression of cancer cells to become androgen-refractory and metastatic. Eicosanoid products of the cyclooxygenase (COX) and lipoxygenase (LOX) pathways are important mediators of the proliferation of prostate cancer cells in culture and regulate tumour vascularisation and metastasis in animal models. Pharmacological agents that block either COX or LOX products effectively reduce the size of prostate cancer xenografts. Recently, phospholipase A(2) (PLA(2)) enzymes, which regulate the provision of arachidonic acid to both COX- and LOX-derived eicosanoids, are found to also regulate the growth of prostate cancer cells and tumours, with one enzyme, secreted PLA(2)-IIA, being increased in prostate cancer tissues. Annexin A1 and A2, known inhibitors of cytosolic phospholipase A(2)-alpha activity, are absent in prostate cancer tissues. We propose that PLA(2) enzyme function is dysregulated by aberrant up regulation of secreted enzymes and downregulation of endogenous inhibitors of cytosolic phospholipase A(2) activity in prostate cancer and that this dysregulation contributes to the pathogenesis of prostate cancer. Thus, in addition to COX and LOX enzymes, PLA(2) enzymes represent important targets for the treatment of prostate cancer.

Molecular cloning and characterization of a novel androgen repressible gene expressed in the prostate epithelium

Prostate cancer deaths are due to functional escape of prostate cancer cells from their original androgen-dependent growth. To better understand the origin and evolution of hormone-refractory prostate cancer, it is important to identify and characterize genes expressed in the androgen-deprived prostate. We have verified that the rudimentary prostate of congenital androgen deficient mice (hpg) is indeed androgen independent. Using suppression subtractive hybridization between mRNA derived from prostates of hypogonadal (hpg) with or without 14 days of testosterone replacement we have cloned a novel gene from the hpg prostate, termed ADMP (for androgen down regulated gene expressed in mouse prostate), that is down regulated by androgens. ADMP expression is strong in hpg mouse prostate, weak in mature castrated mouse prostate and absent in normal intact or androgen-replaced hpg mouse prostates. While ADMP expression is androgen independent in the hpg prostate, it appears to be androgen-dependent in the kidney and brain of normal intact mouse suggesting tissue specific regulation of ADMP by androgens. Human ADMP mRNA expression is suppressed by androgens in the androgen-sensitive LNCaP cell line. The predicted mouse and human protein of 76 amino acids shares sequence similarity to a putative G-protein coupled receptor indicating its possible role in signal transduction. Human ADMP expression was seen predominantly in the prostate epithelium with weaker expression in the fibroblasts and endothelial cells. Cloning and characterization of ADMP has made it feasible to determine its prospective role in the absence of androgens in prostate cancer.

Androgens target prohibitin to regulate proliferation of prostate cancer cells

Proteins involved in the growth response of prostate cancer cells to androgen were investigated by comparing the proteomes of LNCaP cells treated with vehicle or androgen. Whole-cell lysates were separated by two-dimensional PAGE, and HPLC-MS/MS was used to identify androgen-regulated proteins. Prohibitin, a protein with cell-cycle regulatory activity, was shown to be downregulated by 50% following androgen stimulation. Western blot and reverse transcription-PCR experiments confirmed the result and showed that regulation occurs at the level of transcription. To determine the importance of prohibitin in androgen-stimulated growth, we used transient transfection to overexpress the protein and RNA interference to knock down the protein. Subsequent FACS analysis showed that cells with reduced levels of prohibitin showed a slight but reproducible increase in the percentage of population in cell cycle, while cells with increased prohibitin levels showed a clear reduction in the percentage entering cell cycle, following dihydrotestosterone stimulation, when compared to untransfected controls. Confocal microscopy showed localization of prohibitin in the nucleus as well as the mitochondria of LNCaP cells. It therefore seems that the regulation of prohibitin is a vital part of the cellular growth response to androgen stimulation in LNCaPs and prohibitin may have a nuclear regulatory role in cell-cycle progression.

Inhibitory effects of evodiamine on the growth of human prostate cancer cell line LNCaP

Evodiamine, isolated from a Chinese herbal drug named Wu-Chu-Yu, possesses many biological functions. Recently, it has been reported that Wu-Chu-Yu exerts an antiproliferative effect on several cancers. Prostate carcinoma initially occurs as an androgen-dependent tumor and is the second leading cause of cancer death in American males. In the present study, the effect of evodiamine on the growth of androgen-dependent prostate cancer cell line LNCaP in vitro was examined. Based on [3-(4,5-dimethylthiazol-2-yle)2,5-diphenyltetrazolium bromide] (MTT) assay, evodiamine significantly inhibited the growth of LNCaP cells in a concentration-dependent manner. A significant and concentration-dependent inhibitory effect of evodiamine on LNCaP cell growth was observed at 24 hr and persisted for 96 hr. The examination of lactate dehydrogenase (LDH) assay showed that the cytotoxic effects of evodiamine on LNCaP cells were concentration dependent. Furthermore, we examined the influences of evodiamine on cell death and cell cycle. The flow cytometric analysis of evodiamine-treated cells indicated a block of G2/M phase and an elevated level of DNA fragmentation. The G2/M arrest reached a maximum at 24 hr after evodiamine treatment. The G2/M arrest was accompanied by an elevated p34(cdc2) kinase activity and an increase in the protein expression of cyclin B1 and phosphorylated form of p34(cdc2) (Thr 161). Examination of TUNEL showed that evodiamine-induced apoptosis was observed at 24 hr and extended for 72 hr. Evodiamine elevated caspase-3, and caspase-9 activities and the processing of caspase-3 and caspase-9. These results suggested that evodiamine inhibits the growth of prostate cancer cell line, LNCaP, through an accumulation of cell cycle at G2/M phase and an induction of apoptosis.

Phase I trial of patient-oriented vaccination in HLA-A2-positive patients with metastatic hormone-refractory prostate cancer

To evaluate the safety and toxicity of peptide vaccination for patients with metastatic hormone-refractory prostate cancer (HRPC) based on pre-existing peptide-specific cytotoxic T-lymphocyte (CTL) precursors in the circulation, 10 patients positive for human leukocyte antigen (HLA)-A2 with metastatic HRPC were enrolled in a phase I study. Peptide-specific CTL-precursors reactive to 16 kinds of vaccine candidates in the pre-vaccination peripheral blood mononuclear cells (PBMCs) were measured, and patients were followed by vaccination with only positive peptides (up to 4 kinds of peptides). Serum prostate-specific antigen (PSA) levels were monitored regularly. The peptide vaccination was safe and well tolerated with no major adverse effects. The most common toxicities were dermatologic reactions at the injection site. Increased CTL response to peptides was observed in 4 of 10 patients. Anti-peptide IgG was also detected in post-vaccination sera of 7 of 10 patients. One patient showed the disappearance of a pelvic bone metastasis after five vaccinations. Three patients showed a decrease of serum PSA level from the baseline after the vaccination, but no patients showed a serum PSA level decrease of >/= 50%. The median survival duration of study patients was 22 months with follow-up from 3 to 27 months. We consider that the increase in cellular and humoral immune responses, and decrease in PSA level in some patients justify further development of peptide vaccination for metastatic HRPC patients.

Dosimetric and technical considerations for interstitial adenoviral gene therapy as applied to prostate cancer

PURPOSE

To introduce a simple and specific dosimetric model and an adenoviral delivery technique for interstitial adenoviral gene therapy of prostate cancer.

METHODS AND MATERIALS

CG7060, a PSA-specific, replication-competent adenovirus, was used in a Phase I study in the treatment of 20 patients with locally recurrent prostate cancer. The virus was delivered directly into the prostate via transperineal needles under real-time transrectal ultrasonography guidance. Up to 80 aliquots of 0.1-mL viral solution were injected into the prostate. The injection pattern, effective treatment volume (V(eff)), and viral dose distribution were determined according to a simple dosimetric model in which the local dose of virus was defined as the concentration of the delivered virion uniformly distributed in a sphere of 5-mm radius per injection. The initial dosimetric parameters were measured through scans of contrast solutions in dog prostate glands. The biochemical response (the reduction of serum PSA) as a function of the viral dose and tumor volume coverage was analyzed.

RESULTS

A 0.1-mL solution injected into the dog prostate gland spreads via 4-mm mechanical flow plus 1-mm molecular diffusion. Multiple injections into the prostate of patients resulted in considerable enlargement of the prostate gland. The biochemical response probability for patients treated with CG7060 may be estimated by 1 - alpha * exp[-[beta + gamma (PTV/V(eff)) P/A] * P], where alpha, beta, and gamma are constants; A is the number of aliquots, and P is the integral dose of initial viruses.

CONCLUSION

A simple dosimetric model based on results from our recently reported Phase I study can quantify the biochemical response of patients treated with CG7060 adenoviral therapy. The model predicts that outcome is influenced by the integral dose of delivered virus and the target volume coverage. This first dosimetric model for interstitial adenoviral therapy will serve as a basis for quantitative analysis for ongoing and future studies.

Comparative studies of the estrogen receptors beta and alpha and the androgen receptor in normal human prostate glands, dysplasia, and in primary and metastatic carcinoma

An antibody, GC-17, thoroughly characterized for its specificity for estrogen receptor-beta (ER-beta), was used to immunolocalize the receptor in histologically normal prostate, prostatic intraepithelial neoplasia, primary carcinomas, and in metastases to lymph nodes and bone. Comparisons were made between ER-beta, estrogen receptor-alpha (ER-alpha), and androgen receptor (AR) immunostaining in these tissues. Concurrently, transcript expression of the three steroid hormone receptors was studied by reverse transcriptase-polymerase chain reaction analysis on laser capture-microdissected samples of normal prostatic acini, dysplasias, and carcinomas. In Western blot analyses, GC-17 selectively identified a 63-kd protein expressed in normal and malignant prostatic epithelial cells as well as in normal testicular and prostatic tissues. This protein likely represents a posttranslationally modified form of the long-form ER-beta, which has a predicted size of 59 kd based on polypeptide length. In normal prostate, ER-beta immunostaining was predominately localized in the nuclei of basal cells and to a lesser extent stromal cells. ER-alpha staining was only present in stromal cell nuclei. AR immunostaining was variable in basal cells but strongly expressed in nuclei of secretory and stromal cells. Overall, prostatic carcinogenesis was characterized by a loss of ER-beta expression at the protein and transcript levels in high-grade dysplasias, its reappearance in grade 3 cancers, and its diminution/absence in grade 4/5 neoplasms. In contrast, AR was strongly expressed in all grades of dysplasia and carcinoma. Because ER-beta is thought to function as an inhibitor of prostatic growth, androgen action, presumably mediated by functional AR and unopposed by the beta receptor, may have provided a strong stimulus for aberrant cell growth. With the exception of a small subset of dysplasias in the central zone and a few carcinomas, ER-alpha-stained cells were not found in these lesions. The majority of bone and lymph node metastases contained cells that were immunostained for ER-beta. Expression of ER-beta in metastases may have been influenced by the local microenvironment in these tissues. In contrast, ER-alpha-stained cells were absent in bone metastases and rare in lymph nodes metastases. Irrespective of the site, AR-positive cells were found in all metastases. Based on our recent finding of anti-estrogen/ER-beta-mediated growth inhibition of prostate cancer cells in vitro, the presence of ER-beta in metastatic cells may have important implications for the treatment of late-stage disease.

Cytometric analysis of Fas and Bcl-2 expression in normal prostatic epithelium and prostate cancer

The apoptosis-inducer Fas and the apoptosis-suppresser Bcl-2 are members of the tumor necrosis factor receptor and Bcl-2 gene superfamilies, respectively. Bcl-2 is overexpressed in hormonally refractory prostate cancer. Fas is expressed in several prostatic carcinoma cell lines but its in vivo expression in normal prostate and in prostate cancer is poorly understood. Formalin-fixed tissue sections from 10 benign prostatic hyperplasias, 10 low-grade and 10 high-grade organ-confined prostate cancers, and 6 metastatic prostate cancers were evaluated for immunoreactivity with Fas and Bcl-2 monoclonal antibodies. In addition, Fas expression was quantitated by computerized cytometry. The results were compared by one-way analysis of variance followed by Bonferroni tests. In benign prostate samples, Bcl-2 and Fas were expressed on basal cells and secretory cells, respectively. Bcl-2 was not expressed in any organ-confined tumors and only in one of six metastatic tumors (17%). Fas was expressed in all organ-confined tumors and in two of six metastatic tumors (33%). Fas expression was significantly decreased (P < 0.001) in prostate cancer (0.20 pg/cell) compared with benign prostate (0.79 pg/cell). The decrease was inversely related to the malignant grade of the tumors (0.30 pg/cell in low-grade tumors, 0.19 pg/cell in high-grade tumors, and 0.003 pg/cell in metastatic tumors). Based on these preliminary data, decreased expression of Fas appears to be an early molecular event in prostate cancer. The decline begins in low-grade tumors. The lowest expression occurs in metastatic carcinomas, which are often Fas negative. Overexpression of Bcl-2 appears to be a later and unrelated molecular event. Both abnormalities may be implicated in tumor progression by prolonging tumor cell survival.

Interaction between protein tyrosine phosphatase and protein tyrosine kinase is involved in androgen-promoted growth of human prostate cancer cells

Steroid hormones play key roles in regulating cell proliferation and differentiation in targeting tissues. However, in advanced cancers, the steroid hormone regulation is frequently attenuated through a yet unknown mechanism even in the presence of functional steroid hormone receptors. We investigate the functional role of tyrosine phosphorylation signaling in the hormone-refractory growth of human prostate tumors. Initial studies demonstrate that the androgen-responsive phenotype of human prostate cancer cells associates with a low phosphotyrosine (p-Tyr) level of ErbB-2, which is regulated by cellular prostatic acid phosphatase (PAcP), a protein tyrosine phosphatase. In prostate cancer cells, the p-Tyr level, but not the protein level, of ErbB-2 inversely correlates with the androgen-responsiveness of cell proliferation. Androgen-stimulated cell growth concurs with a down-regulation of cellular PAcP, an elevated p-Tyr level of ErbB-2, and the activation of mitogen-activated protein kinases. Furthermore, only the ErbB-2 inhibitor AG 879, but not the EGFR inhibitor AG 1478, abolishes androgen-induced cell proliferation. Forced expression of ErbB-2 can also attenuate androgen promotion of cell growth. Data taken collectively conclude that in human prostate cancer cells, the tyrosine phosphorylation of ErbB-2 regulated by cellular PAcP plays a key role in regulating androgen-mediated proliferation signaling. Oncogene (2000).

Expression of gonadotropin-releasing hormone receptor mRNA in the rat ventral prostate and dunning R3327 PAP adenocarcinoma before and after castration

BACKGROUND

Continuous administration of gonadotropin-releasing hormone (GnRH) agonists in prostate cancer patients results in involution of the tumors due to suppression of androgen production. In addition to the effect of GnRH at the hypothalamic-pituitary level, experiments in vitro on breast, ovary, and prostatic cells have shown an inhibition of cell proliferation, indicating the presence of local GnRH receptors (GnRH-R). The aim of the present study was to investigate the expression of GnRH-R mRNA in the normal rat ventral prostate (VP) and Dunning R3327 PAP adenocarcinoma and to evaluate the effects of castration on receptor mRNA expression.

METHODS

RNA was prepared from ovaries, pituitaries, VP, and Dunning tumors from both intact and castrated animals. GnRH-R mRNA levels were quantified by a competitive reverse transcription-polymerase chain reaction (RT-PCR) method.

RESULTS

GnRH-R mRNA was detected in normal VP and Dunning tumors. Normal VP showed lower amounts of GnRH-R mRNA compared to Dunning tumors. An elevation of mRNA expression was observed 7 days after castration in Dunning tumors.

CONCLUSIONS

GnRH-R mRNA was found in both VP and Dunning tumors, indicating the presence of a local GnRH system. Normal VP showed lower amounts of GnRH-R mRNA when compared to malignant tissues. GnRH-R mRNA levels were elevated in Dunning tumors following castration.

Amplification of the androgen receptor gene is associated with P53 mutation in hormone-refractory recurrent prostate cancer

p53 protein expression of 30 hormone-refractory locally recurrent prostate cancers was compared with their matched untreated primary tumour specimens. In addition, androgen receptor (AR) gene amplification and p53 protein immunostaining were compared. p53 positivity increased during hormonal therapy from 17 per cent of the untreated primary tumours to 40 per cent of the hormone-refractory recurrences (p = 0.078). None of the p53-positive primary tumour specimens lost p53 positivity during hormonal therapy. Hormone-refractory recurrences with AR gene amplification more frequently (p = 0.0342) showed positive p53 immunostaining than tumours without AR gene amplification, 75 and 27 per cent, respectively. In summary, this study has shown that a cell clone with P53 mutation seems to be selected for during endocrine therapy and that positive p53 immunostaining correlates with AR gene amplification. These results suggest that inactivation of P53 may lead to genetic instability in a subset of prostate carcinomas enabling them to achieve properties, such as AR gene amplification, that allow them to grow in low levels of androgens and therefore cause tumour progression.

Correlation of medical dosimetry quality indicators to the local tumor control in patients with prostate cancer treated with iodine-125 interstitial implants

The treatment of prostate cancer by 125I interstitial implants has been extensively studied with mixed results by one institution or another. A recent study from Hahnemann [Int. J. Radiat. Oncol., Biol., Phys. 21,955-960 (1991)] reported results that were extremely poor compared to those reported in an earlier study at Yale [Int. J. Radiat. Oncol., Biol., Phys. 14, 1153-1157 (1988)] or those in an Eastern Virginia Study [Cancer 63, 2415-2420 (1989)]; differences in 5-yr survival rates being more than a factor of 2. Such large discrepancies from institution to institution led us to a reexamination of the dosimetry. This study analyzed quantitatively three-dimensional dosimetric parameters of 110 prostate cancer patients treated with 125I interstitial implants. The study searched for "cutoff" values in each parameter that divided the patients into two groups with statistically significant differences in the local recurrence-free survival rates. A comparison of the three-dimensional isodose surfaces of patients with favorable values in all of the parameters to those patients with all unfavorable parameters show how these characteristics translated into poor dose coverage and much inhomogeneity within the implant even for cases that met the traditional criteria for adequacy (160 Gy to the tumor volume). Patients in the favorable group had 10-yr survival rates higher by a factor of up to 2 compared to those in the unfavorable group. The strong correlation of three-dimensional volume-dose parameters to the local control rate observed in this study further emphasizes how important it is to assess the three-dimensional dosimetric adequacy of interstitial implants before deciding on their clinical efficacy. If implants are performed with appropriate attention to dosimetry parameters, excellent clinical results are obtained. On the other hand, if dosimetry parameters are not correct, the implant results can be poor.

Expression of human prostatic acid phosphatase correlates with androgen-stimulated cell proliferation in prostate cancer cell lines

Androgen plays a critical role in regulating the growth and differentiation of normal prostate epithelia, as well as the initial growth of prostate cancer cells. Nevertheless, prostate carcinomas eventually become androgen-unresponsive, and the cancer is refractory to hormonal therapy. To gain insight into the mechanism involved in this hormone-refractory phenomenon, we have examined the potential role of the androgen receptor (AR) in that process. We have investigated the expression of AR and two prostate-specific androgen-responsive antigens, prostatic acid phosphatase (PAcP) and prostate-specific antigen (PSA), for the functional activity of AR in LNCaP and PC-3 human prostate carcinoma cells. Our results are as follows. (i) Clone 33 LNCaP cells express AR, PAcP, and PSA, and cell growth is stimulated by 5alpha-dihydrotestosterone (DHT). Stimulation of cell growth correlates with decreased cellular PAcP activity. (ii) In clone 81 LNCaP cells, the expression of PAcP decreases with a concurrent decrease in the degree of androgen stimulation of cell growth, whereas the expression of PSA mRNA level is up-regulated by DHT, as in clone 33 cells. Conversely, in PAcP cDNA-transfected clone 81 cells, an additional expression of cellular PAcP correlates with an increased stimulation by androgen, higher than the corresponding control cells. (iii) PC-3 cells express a low level of functional AR with no detectable PAcP or PSA, and the growth of PC-3 cells is not affected by DHT treatment. Nevertheless, in two PAcP cDNA-transfected PC-3 sublines, the expression of exogenous cellular PAcP correlates with androgen stimulation. This androgen stimulation of cell growth concurs with an increased tyrosine phosphorylation of a phosphoprotein of 185 kDa. In summary, the data indicate that the expression of AR alone is not sufficient for androgen stimulation of cell growth. Furthermore, in AR-expressing prostate cancer cells, the expression of cellular PAcP correlates with androgen stimulation of cell proliferation.

Endocrine therapy of prostate cancer

Endocrine therapy is effective treatment for patients with metastatic prostate cancer. Most patients will benefit from androgen withdrawal in terms of symptomatic relief and delay in progression of diseases. It does not, however, cure patients with metastatic prostate cancer. This finding emphasizes the need for the development of effective nonendocrine therapies.

Cellular changes in prostatic carcinoma after treatment with orchidectomy, estramustine phosphate and medroxyprogesterone acetate

Thirty-three patients with prostatic carcinoma were treated with either estramustine phosphate, orchidectomy or high dose medroxyprogesterone acetate. Therapy response was evaluated by cytological examination of fine needle aspiration biopsies performed before and after 6 weeks treatment. At follow-up, 11 of 14 patients treated with estramustine phosphate had regressive and/or degenerative changes, in 2 patients there were no prostatic carcinoma cells in the smears and in one there was a marked reduction of the number of tumour cells. In 7 of 10 patients treated with orchidectomy there was a marked reduction of the percentage of malignant cells while smears from 3 patients were unchanged. In the 8 patients treated with high dose medroxyprogesterone acetate the cell patterns were unmodified compared with before treatment. We conclude that, in contrast to the lack of effect of treatment with medroxyprogesterone acetate, treatment with orchidectomy and especially estramustine phosphate caused morphologic cellular changes in prostatic carcinoma.

Expression of transforming growth factor-beta 1 in rat ventral prostate and Dunning R3327 PAP prostate tumor after castration and estrogen treatment

BACKGROUND

In normal prostate, TGF-beta 1 is associated to castration induced apoptosis. Combined castration and estrogen treatment, but not castration alone, induces apoptosis in the Dunning R3327 PAP adenocarcinoma.

METHODS

TGF-beta 1 expression in rat ventral prostate (VP) and Dunning R3327 PAP tumor was studied after castration and estrogen treatment, using competitive RT-PCR, in situ hybridization and immunohistochemistry.

RESULTS

TGF-beta 1 mRNA level was 6 times higher in the tumor than in the VP. Combined castration and estrogen treatment increased TGF-beta 1 mRNA levels in the tumor from day 3, while castration did not. The TGF-beta 1 expression was located in the epithelial cells.

CONCLUSIONS

The Dunning R3327 PAP tumor contains high levels of TGF-beta 1, which are further increased by combined castration and estrogen treatment. However, since this increase is not apparent until day 3, TGF-beta 1 probably does not contribute to the known induction of apoptosis in the tumor at day 1 after combined castration and estrogen treatment.

Effect of concomitant administration of clodronate and estramustine phosphate on their bioavailability in patients with metastasized prostate cancer

Estramustine phosphate is generally used as a second-line treatment in patients with advanced prostate cancer. The bone metastases due to the cancer are often treated simultaneously with clodronate in order to relieve the bone pain. Therefore, the interaction of clodronate (800 mg orally four times daily) and estramustine phosphate (280 mg orally twice daily) on their bioavailability was studied in twelve patients with prostate carcinoma and bone metastases. The drugs were first given separately, each to six patients, for five days, and then concomitantly for the same period. The bioavailabilities of the drugs were calculated on the last day of each treatment period. When clodronate was given alone, its concentrations in serum and AUC for one dose interval (6 hr) did not differ from those obtained with the drug given concomitantly with estramustine phosphate, nor did the combination of estramustine phosphate change the excretion of clodronate in urine. The serum concentrations of estramustine phosphate were elevated by about 80% when the drug was given together with clodronate. The AUC for one dose interval (12 hr) was also significantly higher for estramustine phosphate with clodronate than without clodronate. The urinary excretion of estrone, a major metabolite of estramustine phosphate, was also significantly higher after the admission with clodronate. The results suggest that clodronate increases the oral bioavailability of estramustine phosphate.

Quantitative bone scintigraphy in patients with prostatic carcinoma treated with LH-RH analogues

In 14 men with prostatic carcinoma, quantitative scintigraphy of the vertebrae from Th10 to L5 was performed before and 2 weeks and 2 and 6 months after start of treatment with luteinizing hormone-releasing hormone (LH-RH) analogues. Serum prostate-specific antigen (PSA) was also determined. The patients with normal bone scintigram showed no change in gamma camera count rate during the study, but fall in PSA values. The patients with abnormal bone scintigram responded to treatment with flare phenomenon, with increased count rate at 2 weeks, followed by fall to pretreatment level at 2 months. PSA showed decrease as early as 2 weeks after the start of treatment. Bone scintigraphy was found to be useful before therapy, especially in patients with elevated PSA levels, and after 2 months, when the flare phenomenon had subsided. Serial measurement of PSA provided a guide to disease activity.

Defects of androgen receptor function: from sex reversal to motor neurone disease

The androgen receptor (AR) is a ligand-dependent DNA transcription factor that binds androgens which cause masculinisation of the developing male fetus. Classical abnormalities of receptor function result in the syndrome of androgen resistance, with resultant failure of normal male differentiation. In more recent years, however, mutations in the AR gene have been described in a number of diverse clinical conditions, from male infertility to prostate and breast cancer through to a form of motor neurone disease (Kennedy's disease). This review discusses the various AR gene mutations found in androgen insensitivity syndrome (AIS) and the other conditions described above, and relates how different mutations, or disruption of different functional domains, contributes to the various phenotypes. Mutations that cause complete AIS usually disrupt the DNA or steroid binding ability of the receptor. In partial AIS, mutations generally decrease receptor affinity for ligand, affect thermostability of the protein, or affect the ability of the receptor to activate transcription of responsive genes. Isolated mutations occur in the steroid binding domain of the receptor in prostate cancer, and many cancers have an identical mutation. Similarly, in the two cases of male breast cancer in which AR gene mutations have been described, the mutations in the DNA binding domain of the receptor are alike. In Kennedy's disease a trinucleotide repeat expansion occurs in exon A of the AR gene, which appears to affect ability of the receptor to bind ligand and activate transcription, although the mechanism of neuronal degeneration remains unknown.

Prostate specific antigen levels and clinical response to low dose dexamethasone for hormone-refractory metastatic prostate carcinoma

BACKGROUND

It has been suggested that suppression of adrenal androgens may provide benefit to patients with metastatic prostate cancer refractory to initial hormonal therapy (e.g., orchiectomy).

METHODS

The records of 38 patients with metastatic prostate cancer that had progressed after orchiectomy who were placed subsequently on low dose dexamethasone (DXM) with no other concurrent therapy (36 patients received 0.75 mg twice daily and two received 0.75 mg three times daily) were reviewed. Symptomatic status, prostate specific antigen (PSA) measurements, and available radiographic assessments were recorded. Bone scans were reviewed by an independent, blinded evaluator.

RESULTS

Symptomatic improvement was experienced by 24 patients (63%), 20 (83%) of whom also had decreases in PSA. Prostate specific antigen values decreased in 30 patients (79%) with decreases 50% or greater and 80% or greater in 23 (61%) and 13 (34%) patients, respectively. Of the 23 patients with PSA decreases 50% or greater, 8 (35%) had radiographic evidence of disease regression, 5 (22%) were stable, 7 (30%) had disease progression, and 3 (13%) did not have serial radiographic exams. Flutamide was discontinued shortly before DXM treatment for 2 of the 23 patients.

CONCLUSIONS

Low dose DXM may produce important symptomatic improvement and decreased PSA levels in the majority of patients with hormone-refractory prostate cancer. In addition, a substantial percentage of those patients with decreases in PSA also will have radiographic evidence of disease regression. These results suggest the need for additional prospective controlled studies of DXM as a therapy for hormone-refractory prostate cancer.

The expression of prostatic acid phosphatase is transcriptionally regulated in human prostate carcinoma cells

The expression of prostatic acid phosphatase (PAcP) in three human prostate carcinoma cell lines including LNCaP, DU 145 and PC-3, was studied to explore its potential role as a marker in the progression of prostate cancer. Although Southern blot analysis suggested the presence of PAcP gene in all three prostate carcinoma cell lines, the Northern blot analysis and the reverse transcriptase-polymerase chain reaction (RT-PCR) assay showed that PAcP mRNA can be detected only in LNCaP cells. As one of the major differences between LNCaP cells and PC-3 as well as DU 145 cells is the androgen-sensitivity of LNCaP cells, we then focused on the influence of PAcP expression by the presence of androgen receptor (AR) in human AR cDNA-transfected PC-3 cells and high passages of LNCaP cells. The results demonstrated that the transfection of human AR cDNA into PC-3 cells did not have any detectable effect on the expression of PAcP. Further, in LNCaP cells, while the level of PAcP mRNA diminished upon passage, the AR mRNA level remained approximately the same. Together, these data suggested that the differential expression of PAcP in different prostate carcinoma cells including high passages of LNCaP cells may occur at the transcriptional level and may have little linkage to the expression of AR.

Prostate-specific antigen and prognosis in patients with metastatic prostate cancer--a multivariable analysis of prostate cancer mortality

OBJECTIVE

To analyse the prognostic significance of pre- and post-treatment serum prostate-specific antigen (PSA) levels, together with a variety of other factors, in a multivariable analysis of survival in men with stage D2 prostate cancer.

PATIENTS AND METHODS

Cox's proportional hazards model was used to compare survival in 134 men with stage D2 metastatic prostate cancer followed prospectively over a 4 year period, using both univariable and multivariable models. The influence of the following factors on survival was analysed: pre- and post-treatment PSA (both absolute and percentage values), age, treatment, testosterone, pre- and post-treatment alkaline phosphatase (absolute and percentage values), acid phosphatase, haemoglobin, symptom score and performance status and extent of disease on bone scan.

RESULTS

Pre-treatment PSA levels did not significantly influence survival. Similarly, a low absolute post-treatment PSA level at 3 months after the start of treatment conferred no survival advantage relative to patients with a high PSA level at this time. A post-treatment percentage PSA of < 10% at 2, 3 and 6 months after commencement of treatment was associated with prolonged survival. Low pre-treatment alkaline phosphatase (less than the upper limit of normal) and high pre-treatment testosterone levels (> or = 10 nmol/L) were similarly associated with prolonged survival.

CONCLUSIONS

The strong influence of post-treatment percentage PSA on survival in patients with stage D2 prostate cancer suggests that the percentage change in bulk of metastatic deposits is more important in determining survival than the absolute volume of tumour. Pre-treatment alkaline phosphatase seems to be a better indicator of tumour activity than pre-treatment PSA. These findings have important implications for the design and analysis of clinical trials of new therapies in men with stage D2 prostate cancer and for the future selection of alternative treatments for patients with this stage of the disease.

Growth inhibition of androgen-insensitive human prostate carcinoma cells by a 19-norsteroid derivative agent, mifepristone

Mifepristone, also known as RU 486, is a 19-norsteroid derivative. Currently, mifepristone is being tested in clinical trials on meningioma and breast cancer. In this study we analyzed whether mifepristone could inhibit the growth of human prostate cancer cells including androgen-insensitive (PC-3 and DU145) and androgen-sensitive (LNCaP) cell lines. At 1-nM concentration, mifepristone exhibited a marginal stimulatory action on LN-CaP and PC-3 cells. Nevertheless, a dose-dependent growth inhibition on those same cell lines was observed at concentrations of 1 microM and 10 microM. Twenty-day exposure to the clinically achievable concentration of 1 microM mifepristone resulted in consistent inhibition of all three cell lines studied. Furthermore, this in vitro growth inhibition was reflected in an in vivo nude mouse system. Mifepristone at the dosage of 4 mg/100 g body weight completely suppressed the growth of PC-3 tumors for 21 days, although this was followed by a growth rate similar to that of the control tumor. To understand the possible mechanism of mifepristone inhibition, PC-3 cells were exposed to mifepristone in comparison with dexamethasone (Dex), progesterone, and 5 alpha-dihydrotestosterone (DHT), each at 1-microM concentration. The results demonstrated that while both DHT and Dex alone had essentially no effect on cell growth, progesterone alone resulted in a 20% growth inhibition, while mifepristone had more than 60% inhibition with a 16-day exposure. At an equal concentration, the degree of growth inhibition of PC-3 cells by mifepristone or progesterone was partially diminished by simultaneous exposure to Dex. In conclusion, our results demonstrated that the growth of androgen-insensitive prostate cancer cells can be directly inhibited by mifepristone in cultures. This in vitro inhibition is reflected in xenografted tumors.

The potential for hormonal prevention trials

Breast and prostate cancer are significant causes of morbidity and mortality and are very similar in etiology, epidemiology, and modalities of treatment. Investigational strategies in the prevention of these malignancies also have strong parallels. The National Cancer Institute is sponsoring several large scale clinical trials involving hormonal manipulation and cancer prevention. In the Breast Cancer Prevention Trial, 16,000 women at high risk for breast cancer are being randomized to receive the antiestrogen agent tamoxifen or placebo for 5 years in an effort to determine if breast cancer development can be inhibited. In a similar trial, the Prostate Cancer Prevention Trial, 18,000 men older than 55 years of age will be randomized to receive finasteride, a 5-alpha-reductase inhibitor, or placebo to determine if inhibition of dihydrotestosterone synthesis in the prostate over a prolonged period will lead to a decreased incidence of prostate cancer. Both clinical trials offer the possibility of demonstrating that a hormonal intervention can decrease an individual's risk of developing breast or prostate cancer. They also have the potential of providing critical information about cancer risk, etiology, screening, and genetics, as well as quantifying the risks and benefits of specific preventive interventions.

Neurotensin is an autocrine trophic factor stimulated by androgen withdrawal in human prostate cancer

After therapeutic hormone deprivation, prostate cancer cells often develop androgen-insensitive growth through mechanisms thus far undefined. Neuropeptides have been previously implicated as growth factors in some prostate cancers. Here, we demonstrate that androgen-sensitive LNCaP human prostate cancer cells produce and secrete neurotensin following androgen withdrawal. We show that while LNCaP cells express the neurotensin receptor, only androgen-deprived cells exhibit a growth response to exogenous neurotensin. We further demonstrate that androgen-stimulated cells may be refractory to exogenous neurotensin due to androgen induction of a metalloprotease active toward neurotensin. Thus, prostate cancer cells deprived of androgen develop an alternative autocrine growth mechanism involving neurotensin.

The effect of clodronate on bone in metastatic prostate cancer. Histomorphometric report of a double-blind randomised placebo-controlled study

57 patients with advanced prostate cancer and a failure of prior hormonal treatment were selected for a double-blind placebo-controlled trial, in which they were randomly allocated to receive either clodronate (C) or placebo concomitantly with the basic cancer treatment, estramustine phosphate (E) (560 mg daily). The treatment was started intravenously with 300 mg of C or placebo in 5 consecutive days, and thereafter maintained orally with 1600 mg of C or identical placebo daily for 3 months. Bone biopsies were taken at admission and at 3 months. Measurements of serum calcium, phosphate, alkaline phosphatase, prostate-specific antigen and creatinine were made at the time of both bone biopsies and at 1 month. Serum intact parathyroid hormone and vitamin D metabolites were measured at admission and at 3 months. Because of several discontinuations, the study groups at final analysis comprised 20 patients taking E + C and 19 patients taking E and placebo. Bone resorption, as judged by eroded surface and osteoclast number, was markedly increased especially in biopsies taken from tumour-involved bone. Treatments with E + C or E both induced a significant decrease in bone resorption, but were associated with the development of hypocalcaemia, secondary hypoparathyroidism, hypophosphataemia and severe impairment of mineralisation of newly formed bone, i.e. osteomalacia. Since the patients were not vitamin D deficient, we conclude that osteomalacia resulted from a relative deficiency of calcium and phosphate. The transiency of pain relief achieved with anti-resorptive agents in the treatment of bone metastases from prostate cancer may be due to the development of osteomalacia.

Androgen receptor gene mutations in human prostate cancer

To investigate the structural abnormality of the androgen receptor (AR) in human prostate cancers, exons B-H encoding DNA- and hormone-binding domains were examined by single-strand conformation polymorphism analysis of polymerase chain reaction products using originally designed oligoprimers. Tissues from 7 cases of untreated stage B prostate cancer surgically removed and from 8 cases of endocrine therapy-resistant cancers obtained at autopsy were used in the study. Two different mutations were identified in exons D and H in the different cancer foci of the same cancer death patient. One mutation in exon D (at codon 701, Leu to His) was detected in the prostate, and the other in exon H (at codon 877, Thr to Ala) was found in metastatic tissues. In untreated cancer tissues and the other autopsy samples, no mutations were detected. The mutation in exon H was identical to that reported in LNCaP cells. These results indicate that AR gene mutations occur in relation to endocrine therapy-resistance, although the mutation was found in 1 out of 8 resistant cases (12.5%) at autopsy.

Radiation therapy for prostate cancer. Long-term results and implications for future advances

BACKGROUND

There are surprisingly few studies that concurrently report the 10-year overall survival (OS) rate, 10-year adjusted survival (AS) rate, 10-year recurrence free (NED) survival rate, and 10-year local tumor control (LC) rate using external beam radiation therapy (RT) for Stages A2, B, and C prostate cancer. A simultaneous analysis of OS, AS, NED survival, and LC rates is useful in terms of establishing priorities for future research efforts.

METHODS

Actuarial LC, NED survival, AS, and OS rates were analyzed for 289 patients with Stages A2, B, and C prostate cancer treated with RT between 1975 and 1990 in the Department of Therapeutic Radiology, Yale University School of Medicine.

RESULTS

The 10-year LC, NED survival, AS, and OS rates for 168 patients with Stage A2 and B disease were 88% (standard error [SE], 5%), 50% (SE, 10%), 70% (SE, 7%), and 38% (SE, 7%), respectively. The 10-year LC, NED survival, AS, and OS rates for 121 patients with Stage C disease were 82% (SE, 6%), 41% (SE, 6%), 25% (SE, 7%), and 21% (SE, 6%), respectively.

CONCLUSION

External beam radiation provides excellent local clinical tumor control for early prostate cancer. However, 60% of all prostate cancer deaths of patients with Stage A2 and B disease and 76% of all prostate cancer deaths of patients with Stage C disease were attributable to metastatic disease without clinical local failure. The major obstacle in improving the death rate associated with Stages A2, B, and C prostate cancer remains the inability to control metastatic disease; research efforts must concentrate on overcoming this problem.

Transrectal hyperthermia as palliative treatment for advanced adenocarcinoma of prostate and studies of cell-mediated immunity

During a fifteen-month period, 15 patients with progressive adenocarcinoma of the prostate (CaP) were treated with transrectal microwave hyperthermia (TRHT). There were 5 Stage T4 and 11 Stage T3 patients including 6 patients with skeletal metastases. Nine of the patients had severe and 6 had moderately severe signs and symptoms of CaP. TRHT was given six times at 2,450 MHz with temperature controlled at 43.5 degrees for thirty minutes. Cell-mediated immunity tests were performed before TRHT and at two, four, and six months post-therapy. The results of these tests were compared with those of 15 patients with benign prostatic hyperplasia (BPH) treated with the same TRHT and with 30 untreated normal volunteers. TRHT was well tolerated with mild acute toxicity noted in 3 patients (20%). Of the 15 patients treated, 2 (13%) showed scintigraphic evidence of regression of bone metastases. Five patients survived more than five years since treatment, and in 3 patients there was no evidence of CaP. A decrease of marked or moderate degree in signs and symptoms of CaP was noted in 8 patients (53%). The results of cell-mediated immunity tests were of interest. The 15 CaP patients prior to TRHT had lower OKT4/OKT8 ratio, lower PHA transformation index, and lower Con-A induced T-cell suppressor activity as compared with the 15 BPH patients and 30 healthy volunteers, who had normal immune parameters (p < 0.01). Following TRHT there was a significant increase in the monitored immune parameters noted in the 15 CaP patients (p < 0.01). This immune stimulation peaked at two months and gradually decreased to near pretreatment levels at six months. In the 15 BPH patients post-TRHT changes in immune tests were less apparent. The results of this small study, if confirmed, could be of clinical importance in patients with advanced prostate cancer.

Endocrine therapy of advanced carcinoma of the prostate

Increasing evidence suggests that growth of the prostatic tissue is regulated by a network of hormones and growth factors, in which androgens play the prominent role. Hormonal manipulation remains the core of treatment for locally advanced and metastatic prostate cancer. Achievement of a complete androgen blockade, by surgical or medical means or a combination of both, offers superior results in palliative management of advanced disease. Management of hormonal refractory cancer, however, remains a challenge to clinicians.

The role of neoadjuvant hormonal manipulation in localized prostatic cancer

BACKGROUND

Although hormonal manipulation is standard therapy for patients with metastatic prostatic cancer, its use in localized disease in combination with surgical extirpation of the gland has not been investigated thoroughly and systematically.

METHODS

The authors report their initial pilot studies using preoperative neoadjuvant endocrine therapy.

RESULTS

Although marked reduction in serum prostate-specific antigen (PSA) levels occurred in all patients, the PSA level after endocrine manipulation did not predict the pathologic stage. In addition, immunohistochemical staining of the radical prostatectomy specimen for PSA, in several patients with a zero serum PSA level, after endocrine therapy revealed intense PSA staining in the cancer cells but not in benign epithelium. The effects on tumor downstaging were inconclusive. Overall, only 33% of patients had organ-confined disease, but in some patients, complete tumor regression (PO) occurred.

CONCLUSIONS

Neoadjuvant hormonal therapy in prostatic cancer, although definitely not standard therapy, bears investigation. In addition to the effect on the "index" cancer, it also provides an opportunity to evaluate the effect of hormonal agents on microfocal ("early") cancer and known precursors of malignant change. Therefore, it may provide a means of assessing agents of potential use in the development of chemopreventive strategies.

Evaluation of the effect of oral clodronate on skeletal metastases with type 1 collagen metabolites. A controlled trial of the Finnish Prostate Cancer Group

Clodronate relieves bone pain in patients with skeletal metastases. Since the pain relieving mechanism of clodronate may be associated with the antiosteoclastic activity, we have investigated whether the drug has simultaneous actions on bone resorption and pain. Although osteosclerotic metastases are characteristic of prostate carcinoma, bone resorption is also accelerated. The resorbing process can be investigated using a specific immunoassay for ICTP (cross-linked carboxyterminal telopeptide region of type I collagen) which allows the measurement of the degradation of type I collagen in serum samples. We have also determined serum concentration of PICP (carboxyterminal propeptide of type I procollagen) which reflects the synthesis of type I collagen (osteoid). Patients who have relapsed after first-line hormonal therapy, were randomised to receive estramustine phosphate (E) with or without clodronate (C) (E + C, n = 50; E, n = 49). The dose of E was 560 mg and that of C 3.2 g for the first month, thereafter 1.6 g. We saw elevated ICTP and PICP levels in the majority of the patients. A transient decrease in ICTP values occurred simultaneously with pain relief. The changes were more accentuated in the E + C than in the E group but the difference was not significant. In each group serum phosphate concentration decreased markedly (P = 0.001) whereas the activity of alkaline phosphatase remained increased, both indicating a development of osteomalacia during E therapy. The short-term antiosteoclastic effect of C may be explained by the dose reduction, hyperosteoidosis and osteomalacia which inhibit the binding of C on the crystal surfaces and by the late phase of disease.