Phase IIA Clinical Trial to Test the Efficacy and Safety of Toremifene in Men with High-Grade Prostatic Intraepithelial Neoplasia

Estrogen receptor expression is modulated in human and mouse prostate epithelial cells during cancer progression

Substantial data posit estrogen receptors (ERs) as promising targets for prostate cancer (PCa) therapeutics. However, the trials on assessing the chemo-preventive or therapeutic potential of ER targeting drugs or selective estrogen receptor modulators (SERMs) have not yet established their clinical benefits. This could be ascribed to a possible modulation in the ER expression during PCa progression. Further it is warranted to test various ER targeting drugs in appropriate preclinical models that simulate human ER expression pattern during PCa progression. The study was undertaken to revisit the existing data on the epithelial ER expression pattern in human cancerous prostates and experimentally determine whether these patterns are replicated in TRAMP (Transgenic Adenocarcinoma of Mouse Prostate) mice, a model for human PCa. Estradiol (E2) binding to the plasma membrane of the epithelial cells and its modulation during the PCa progression in TRAMP were also investigated. A reassessment of the existing data revealed a trend towards downregulation in the epithelial expression of wild-type ESR1 transcripts in high-grade PCa, compared to non-cancerous prostate in humans. Next, epithelial cell-enriched populations from TRAMP prostates (TP) displaying low-grade prostatic intraepithelial neoplasia (LGPIN), high-grade PIN (HGPIN), HGPIN with well-differentiated carcinoma (PIN + WDC), WDC (equivalent to grade 2/3 human PCa), and poorly-differentiated carcinoma (PDC-equivalent to grade 4/5 human PCa) revealed significantly higher Esr1 and Esr2 levels in HGPIN and significantly reduced levels in WDC, compared to respective age-matched control prostates. These patterns for the nuclear ERs were similar to the trend shown by E2 binding to the plasma membrane of the epithelial cells during PCa progression in TRAMP. E2 binding to epithelial cells (EpCAM+), though significantly higher in TPs displaying LGPIN, decreased significantly as the disease progressed to WDC. The study highlights a reduction in the epithelial ESR level with the PCa progression and this pattern was evident in both humans and TRAMP. These observations may have major implications in refining PCa therapeutics targeting ER.

Hormonally Regulated Myogenic miR-486 Influences Sex-specific Differences in Cancer-induced Skeletal Muscle Defects

Cancer-induced skeletal muscle defects show sex-specific differences in severity with men performing poorly compared to women. Hormones and sex chromosomal differences are suggested to mediate these differences, but the functional skeletal muscle markers to document these differences are unknown. We show that the myogenic microRNA miR-486 is a marker of sex-specific differences in cancer-induced skeletal muscle defects. Cancer-induced loss of circulating miR-486 was more severe in men with bladder, lung, and pancreatic cancers compared to women with the same cancer types. In a syngeneic model of pancreatic cancer, circulating and skeletal muscle loss of miR-486 was more severe in male mice compared to female mice. Estradiol (E2) and the clinically used selective estrogen receptor modulator toremifene increased miR-486 in undifferentiated and differentiated myoblast cell line C2C12 and E2-inducible expression correlated with direct binding of estrogen receptor alpha (ERα) to the regulatory region of the miR-486 gene. E2 and toremifene reduced the actions of cytokines such as myostatin, transforming growth factor β, and tumor necrosis factor α, which mediate cancer-induced skeletal muscle wasting. E2- and toremifene-treated C2C12 myoblast/myotube cells contained elevated levels of active protein kinase B (AKT) with a corresponding decrease in the levels of its negative regulator PTEN, which is a target of miR-486. We propose an ERα:E2-miR-486-AKT signaling axis, which reduces the deleterious effects of cancer-induced cytokines/chemokines on skeletal muscle mass and/or function.

Tumor-Associated Macrophages Induce Endocrine Therapy Resistance in ER+ Breast Cancer Cells

Antiestrogenic adjuvant treatments are first-line therapies in patients with breast cancer positive for estrogen receptor (ER+). Improvement of their treatment strategies is needed because most patients eventually acquire endocrine resistance and many others are initially refractory to anti-estrogen treatments. The tumor microenvironment plays essential roles in cancer development and progress; however, the molecular mechanisms underlying such effects remain poorly understood. Breast cancer cell lines co-cultured with TNF-α-conditioned macrophages were used as pro-inflammatory tumor microenvironment models. Proliferation, migration, and colony formation assays were performed to evaluate tamoxifen and ICI 182,780 resistance and confirmed in a mouse-xenograft model. Molecular mechanisms were investigated using cytokine antibody arrays, WB, ELISA, ChIP, siRNA, and qPCR-assays. In our simulated pro-inflammatory tumor microenvironment, tumor-associated macrophages promoted proliferation, migration, invasiveness, and breast tumor growth of ER+ cells, rendering these estrogen-dependent breast cancer cells resistant to estrogen withdrawal and tamoxifen or ICI 182,780 treatment. Crosstalk between breast cancer cells and conditioned macrophages induced sustained release of pro-inflammatory cytokines from both cell types, activation of NF-κB/STAT3/ERK in the cancer cells and hyperphosphorylation of ERα, which resulted constitutively active. Our simulated tumor microenvironment strongly altered endocrine and inflammatory signaling pathways in breast cancer cells, leading to endocrine resistance in these cells.

A Study of Combination Bicalutamide and Raloxifene for Patients With Castration-Resistant Prostate Cancer

BACKGROUND

Prostate tissue expresses 2 estrogen receptor (ER) isoforms, ER-α and ER-β, and estrogen-based therapies have shown activity in preclinical studies. Raloxifene, a selective ER modulator, has inhibited the growth of prostate cancer xenograft models and was tested in a phase II trial of castration-resistant prostate cancer (CRPC), with some patients achieving stable disease. However, no studies have examined the safety of the combination of bicalutamide plus raloxifene for CRPC. Therefore, we investigated the safety of treatment with bicalutamide plus raloxifene in patients with CRPC in an initial study.

MATERIALS AND METHODS

We conducted a study to evaluate the toxicity (primary endpoint) of the combination of bicalutamide (50 mg) and raloxifene (60 mg) in 28-day cycles (maximum, 6 cycles) in men with progressive CRPC. The secondary endpoint, quality of life (QOL), was assessed by patients using a 6-item linear analog self-assessment or hormonal domain scale of the Expanded Prostate Cancer Index Composite.

RESULTS

We enrolled 18 patients with CRPC in the study to evaluate the safety of, and patient assessment of QOL (mental, physical, social, emotional, and spiritual) with, bicalutamide plus raloxifene therapy. No grade 3 or 4 adverse events occurred. None of the 18 patients required dose reductions. The patient assessment of QOL showed no statistically significant changes after 2 treatment cycles. The median progression-free survival with bicalutamide plus raloxifene was 1.9 months (95% confidence interval, 1.8-2.8 months).

CONCLUSION

The results of the present study have shown that bicalutamide/raloxifene treatment is well tolerated. However, limited clinical activity occurred in men with CRPC who had previously undergone secondary hormonal therapy or chemotherapy.

Actions of Estrogenic Endocrine Disrupting Chemicals on Human Prostate Stem/Progenitor Cells and Prostate Carcinogenesis

Substantial evidences from epidemiological and animal-based studies indicate that early exposure to endocrine disrupting chemicals (EDCs) during the developmental stage results in a variety of disorders including cancer. Previous studies have demonstrated that early estrogen exposure results in life-long reprogramming of the prostate gland that leads to an increased incidence of prostatic lesions with aging. We have recently documented that bisphenol A (BPA), one of the most studied EDCs with estrogenic activity has similar effects in increasing prostate carcinogenic potential, supporting the connection between EDCs exposure and prostate cancer risk. It is well accepted that stem cells play a crucial role in development and cancer. Accumulating evidence suggest that stem cells are regulated by extrinsic factors and may be the potential target of hormonal carcinogenesis. Estrogenic EDCs which interfere with normal hormonal signaling may perturb prostate stem cell fate by directly reprogramming stem cells or breaking down the stem cell niche. Transformation of stem cells into cancer stem cells may underlie cancer initiation accounting for cancer recurrence, which becomes a critical therapeutic target of cancer management. We therefore propose that estrogenic EDCs may influence the development and progression of prostate cancer through reprogramming and transforming the prostate stem and early stage progenitor cells. In this review, we summarize our current studies and have updated recent advances highlighting estrogenic EDCs on prostate carcinogenesis by possible targeting prostate stem/progenitor cells. Using novel stem cell assays we have demonstrated that human prostate stem/progenitor cells express estrogen receptors (ER) and are directly modulated by estrogenic EDCs. Moreover, employing anin vivohumanized chimeric prostate model, we further demonstrated that estrogenic EDCs initiate and promote prostatic carcinogenesis in an androgen-supported environment. These findings support our hypothesis that prostate stem/progenitor cells may be the direct targets of estrogenic EDCs as a consequence of developmental exposure which carry permanent reprogrammed epigenetic and oncogenic events and subsequently deposit into cancer initiation and progression in adulthood.

Small molecule tolfenamic acid inhibits PC-3 cell proliferation and invasion in vitro, and tumor growth in orthotopic mouse model for prostate cancer

BACKGROUND

Specificity protein (Sp) transcription factors are implicated in critical cellular and molecular processes associated with cancer that impact tumor growth and metastasis. The non-steroidal anti-inflammatory drug, tolfenamic acid (TA) is known to inhibit Sp proteins in some human cancer cells and laboratory animal models. We evaluated the anti-cancer activity of TA using in vitro and in vivo models for prostate cancer.

METHODS

The anti-proliferative efficacy of TA was evaluated using DU-145, PC-3, and LNCaP cells. PC-3 cells were treated with DMSO or 50 µM TA for 48 hr. Whole cell lysates were evaluated for the expression of Sp1, survivin, c-PARP, Akt/p-Akt, c-Met, cdk4, cdc2, cyclin D3, and E2F1 by Western blot analysis. Cell invasion was assessed by Boyden-chamber assay and flow cytometry analysis was used to study apoptosis and cell cycle distribution. An orthotopic mouse model for prostate cancer with PC-3-Luc cells was used to study the in vivo effect of TA.

RESULTS

TA inhibited the expression of Sp1, c-Met, p-Akt, and survivin; increased c-PARP expression and caspases activity in PC-3 cells. TA caused cell arrest at G(0) /G(1) phase accompanied by a decrease in cdk4, cdc2, cyclin D3, and E2F1 and an increase in critical apoptotic markers. TA augmented annexin-V staining, caspase activity, and c-PARP expression indicating the activation of apoptotic pathways. TA also decreased PC-3 cell invasion. TA significantly decreased the tumor weight and volume which was associated with low expression of Sp1 and survivin in tumor sections.

CONCLUSION

TA targets critical pathways associated with tumorigenesis and invasion. These pre-clinical data strongly demonstrated the anti-cancer activity of TA in prostate cancer.

Actions of estrogens and endocrine disrupting chemicals on human prostate stem/progenitor cells and prostate cancer risk

Estrogen reprogramming of the prostate gland as a function of developmental exposures (aka developmental estrogenization) results in permanent alterations in structure and gene expression that lead to an increased incidence of prostatic lesions with aging. Endocrine disrupting chemicals (EDCs) with estrogenic activity have been similarly linked to an increased prostate cancer risk. Since it has been suggested that stem cells and cancer stem cells are potential targets of cancer initiation and disease management, it is highly possible that estrogens and EDCs influence the development and progression of prostate cancer through reprogramming and transforming the prostate stem and early stage progenitor cells. In this article, we review recent literature highlighting the effects of estrogens and EDCs on prostate cancer risk and discuss recent advances in prostate stem/progenitor cell research. Our laboratory has recently developed a novel prostasphere model using normal human prostate stem/progenitor cells and established that these cells express estrogen receptors (ERs) and are direct targets of estrogen action. Further, using a chimeric in vivo prostate model derived from these normal human prostate progenitor cells, we demonstrated for the first time that estrogens initiate and promote prostatic carcinogenesis in an androgen-supported environment. We herein discuss these findings and highlight new evidence using our in vitro human prostasphere assay for perturbations in human prostate stem cell self-renewal and differentiation by natural steroids as well as EDCs. These findings support the hypothesis that tissue stem cells may be direct EDC targets which may underlie life-long reprogramming as a consequence of developmental and/or transient adult exposures.

Pharmacokinetic evaluation of toremifene and its clinical implications for the treatment of osteoporosis

INTRODUCTION

Toremifene is a triphenylethylene selective estrogen receptor modulator (SERM) that differs from tamoxifen in a single chloride ion addition on a side chain, resulting in a potentially more favorable toxicity profile.

AREAS COVERED

This article reviews the pharmacokinetics of toremifene and its potential use for the treatment of osteoporosis. This article was based on articles found through a literature search containing the terms 'toremifene' and 'SERMs.'

EXPERT OPINION

Toremifene can be administered orally with an excellent bioavailability. The overall pharmacokinetic profile is remarkably similar to tamoxifen. Toremifene is highly metabolized in the liver and is eliminated primarily in the feces following enterohepatic circulation. Some of its metabolites retain biological activity. This SERM was approved by the FDA for the treatment of estrogen receptor-positive metastatic breast cancer and is under investigation for its potential skeletal benefits in men on androgen deprivation therapy. Despite the positive preclinical and clinical evidences for the prevention of bone loss and fractures, the chemopreventive effect on prostate cancer remains to be confirmed and an increased risk of venous thromboembolism was evidenced in a large Phase III trial. Thus, additional data are required to establish the full clinical profile of this compound and its potential advantages over antiresorptive agents commonly in use for the treatment of osteoporosis.

Synergistic chemoprotective mechanisms of dietary phytoestrogens in a select combination against prostate cancer

Combination of dietary phytoestrogens with diverse molecular mechanisms may enhance their anticancer efficacy at physiological concentrations, as evidenced in epidemiological studies. A select combination of three dietary phytoestrogens containing 8.33 μM each of genistein (G), quercetin (Q) and biochanin A (B) was found to be more potent in inhibiting the growth of androgen-responsive prostate cancer cells (LNCaP) as well as DU-145 and PC-3 prostate cancer cells in vitro than either 25 μM of G, B or Q or 12.5+12.5 μM of G+Q, Q+B or G+B. Subsequent mechanistic studies in PC-3 cells indicated that the action of phytoestrogens was mediated both through estrogen receptor (ER)-dependent and ER-independent pathways as potent estrogen antagonist ICI-182780 (ICI, 5 μM) could not completely mask the synergistic anticancer effects, which were sustained appreciably in presence of ICI. G+Q+B combination was significantly more effective than individual compounds or their double combinations in increasing ER-β, bax (mRNA expression); phospho-JNK, bax (protein levels); and in decreasing bcl-2, cyclin E, c-myc (mRNA expression); phospho-AKT, phospho-ERK, bcl-2, proliferating cell nuclear antigen (protein levels) in PC-3 cells. Phytoestrogens also synergistically stimulated caspase-3 activity. Our findings suggest that selectively combining anticancer phytoestrogens could significantly increase the efficacy of individual components resulting in improved efficacy at physiologically achievable concentrations. The combination mechanism of multiple anticancer phytochemicals may be indicative of the potential of some vegetarian diet components to elicit chemopreventive effects against prostate cancer at their physiologically achievable concentrations, in vivo.

Endocrine-disrupting chemicals: an Endocrine Society scientific statement

There is growing interest in the possible health threat posed by endocrine-disrupting chemicals (EDCs), which are substances in our environment, food, and consumer products that interfere with hormone biosynthesis, metabolism, or action resulting in a deviation from normal homeostatic control or reproduction. In this first Scientific Statement of The Endocrine Society, we present the evidence that endocrine disruptors have effects on male and female reproduction, breast development and cancer, prostate cancer, neuroendocrinology, thyroid, metabolism and obesity, and cardiovascular endocrinology. Results from animal models, human clinical observations, and epidemiological studies converge to implicate EDCs as a significant concern to public health. The mechanisms of EDCs involve divergent pathways including (but not limited to) estrogenic, antiandrogenic, thyroid, peroxisome proliferator-activated receptor gamma, retinoid, and actions through other nuclear receptors; steroidogenic enzymes; neurotransmitter receptors and systems; and many other pathways that are highly conserved in wildlife and humans, and which can be modeled in laboratory in vitro and in vivo models. Furthermore, EDCs represent a broad class of molecules such as organochlorinated pesticides and industrial chemicals, plastics and plasticizers, fuels, and many other chemicals that are present in the environment or are in widespread use. We make a number of recommendations to increase understanding of effects of EDCs, including enhancing increased basic and clinical research, invoking the precautionary principle, and advocating involvement of individual and scientific society stakeholders in communicating and implementing changes in public policy and awareness.

Endocrine disruptors and prostate cancer risk

There is increasing evidence both from epidemiology studies and animal models that specific endocrine-disrupting compounds may influence the development or progression of prostate cancer. In large part, these effects appear to be linked to interference with estrogen signaling, either through interacting with ERs or by influencing steroid metabolism and altering estrogen levels within the body. In humans, epidemiologic evidence links specific pesticides, PCBs and inorganic arsenic exposures to elevated prostate cancer risk. Studies in animal models also show augmentation of prostate carcinogenesis with several other environmental estrogenic compounds including cadmium, UV filters and BPA. Importantly, there appears to be heightened sensitivity of the prostate to these endocrine disruptors during the critical developmental windows including in utero and neonatal time points as well as during puberty. Thus infants and children may be considered a highly susceptible population for ED exposures and increased risk of prostate cancers with aging.

Strategy for determination of in vitro protein acetylation sites by using isotope-labeled acetyl coenzyme A and liquid chromatography-mass spectrometry

Acetylation of proteins on specific lysine residues by acetyltransferase enzymes is a post-translational modification for biologically relevant regulation. In this study, we proposed a strategy to determine the in vitro acetylation sites of proteins by tracing isotope-labeled acetyl groups using mass spectrometry. Isotope-labeled and unlabeled acetyl groups transferred onto the substrates in vitro result in a specific "mass difference" that can be measured by MS analysis and utilized for localization of potential acetylated peptide signals. The identification of acetylation site is facilitated by conducting MS/MS experiments on those selected signals. Acetylation reactions of substrates were performed in the presence of acetyltransferase and equal molar of isotope-labeled acetyl coenzyme A ([(13)C2-2-D3]-acetyl-CoA) and unlabeled acetyl-CoA. After enzymatic digestion, the resulting peptide mixture was fractionated by off-line, reversed-phase high-pressure liquid chromatography and the accurate mass measurement of peptides was achieved by a quadrupole/time-of-flight mass spectrometer. Signals with 5-Da (or their multiples) mass differences and equal responses were selected out by program computation. Those potential acetylated peptide signals were subjected to MS/MS analyses for determination of acetylation sites. We have used histone H3 peptide (aa 1-20), histone H2B peptide (aa 1-21), histone H2A, and histone H2B proteins as the model compounds to demonstrate the applicability of this analytical scheme for the characterization of in vitro acetylation sites.

Effects of castration on the development of prostate adenocarcinoma from its precursor HGPIN and on the occurrence of androgen-independent, poorly differentiated carcinoma in TRAMP mice

Androgen ablation is thought to exert selective pressure for the development of androgen-independent forms of prostate cancer. This study was set up to investigate the effects of surgical castration on the development of prostate adenocarcinoma (ADC) from its precursor (high-grade prostate intraepithelial neoplasia (HGPIN)) and on the occurrence of androgen-independent, poorly differentiated carcinoma (PDC) in (C57Bl/6 transgenic adenocarcinoma of mouse prostate) TRAMP mice. It was found that castration cures HGPIN and ADC and prevents their further occurrence and growth, but has no effect on PDC. This indicates that in this model, PDC is not the progression of ADC favoured by androgen ablation and that its initiating cells are different from those of HGPIN and ADC.

The role of estrogens and estrogen receptors in normal prostate growth and disease

Estrogens have significant direct and indirect effects on prostate gland development and homeostasis and have been long suspected in playing a role in the etiology of prostatic diseases. Direct effects are mediated through prostatic estrogen receptors alpha (ERalpha) and beta (ERbeta) with expression levels changing over time and with disease progression. The present review examines the evidence for a role of estrogens and specific estrogen receptors in prostate growth, differentiation and disease states including prostatitis, benign prostatic hyperplasia (BPH) and cancer and discusses potential therapeutic strategies for growth regulation via these pathways.

Prevention of Prostate Cancer: What We Know and Where We Are Going

As one of the most prevalent cancers, prostate cancer has enormous public health importance and its prevention seems to be a rational approach to attenuate the economic, emotional, physical, and social impact of this disease. This review discusses some of the options available to clinicians worldwide under the broad headings of chemoprevention and dietary modification including lifestyle issues. From the review of available literature, it is appreciated that although many exciting options such as androgen inhibitors, vitamin E, and selenium are being actively considered, they are far from being included in clinical practice. So until large randomized trials confirm the benefit of chemopreventives and dietary modifications, patients may be advised to pursue a diet and lifestyle that ensures overall fitness.

Fracture risk in Danish men with prostate cancer: a nationwide register study

OBJECTIVE

To assess the risk of fracture attributable to prostate cancer, and the impact of exposure to prescribed gonadotrophin-releasing hormone agonists and antiandrogens on this risk in a nationwide, population-based case-control study.

PATIENTS AND METHODS

Data from the Danish National Hospital Discharge Register, the National Bureau of Statistics, and the National Prescriptions Database were merged. The analysis covered 15 716 men aged >50 years presenting with a fracture at any hospital in Denmark in 2000, and 47 149 age-matched control men. A previous diagnosis of prostate cancer had been recorded in 1.3% of controls and 2.5% of those with a fracture.

RESULTS

Prostate cancer was associated with an increased odds ratio (95% confidence interval) for all fractures of 1.8 (1.6-2.1), for hip fractures of 3.7 (3.1-4.4), but no increased risk of vertebral fractures. The increased fracture risk became apparent early after diagnosis and remained pronounced even in long-term survivors. Androgen deprivation therapy (ADT) with an odds ratio of 1.7 (1.2-2.5; P < 0.01) and orchidectomy, at 1.7 (1.2-2.4; P < 0.01) added to the overall fracture risk. In all, 3.1% of hip fractures in Danish men aged >50 years are attributable to prostate cancer.

CONCLUSION

Prostate cancer, orchidectomy and the use of ADT are associated with a markedly greater risk of fractures, especially of the hip. The risk of hip fracture is not confined to the very old, neither is the risk made negligible by the excess mortality in patients with advanced prostate cancer.

Assessing intraepithelial neoplasia and drug safety in cancer-preventive drug development

Despite significant interest from the research community and the population in general, drug approvals for cancer prevention and/or cancer risk reduction are few. This is due, in part, to the requirement that new cancer-preventive drugs must first be shown to be efficacious in reducing cancer incidence or mortality. Moreover, such drugs need to have proven safety for long-term administration. This process can be improved by focusing on precancer (intraepithelial neoplasia) to identify subjects at risk and prove efficacy in shorter, smaller trials as well as on detecting early markers of potential toxicities of chronic exposure to cancer-preventive drug regimens.

Increased expression of estrogen-related receptor alpha (ERRalpha) is a negative prognostic predictor in human prostate cancer

The nuclear receptor ERRalpha (estrogen-related receptor alpha) is known to modulate the estrogen-signaling pathway, but the biological significance of ERRalpha in the prostate remains unclear. We investigated the expression of ERRalpha in human prostate tissues and cancer cell lines to evaluate the potential roles of the receptor in prostate cancer (PC). Western blot analysis of ERRalpha was performed in three cell lines of human PC (LNCaP, DU145 and PC-3). The expressions of ERRalpha in cancerous lesions (n = 106) and benign foci (n = 99) of 106 surgically obtained prostate specimens were evaluated by immunohistochemistry. The relationships between the ERRalpha expression and clinicopathological features were evaluated. Western blot analysis using the polyclonal anti-ERRalpha antibody detected a 52 kD band in all three PC cell lines. Positive immunostaining of ERRalpha in the nuclei was found in 73 (69%) cancerous and 47 (47.5%) benign epithelium, whereas the stromal tissues were negative for ERRalpha. The mean immunoreactivity score (IR score) of the cancerous lesions (3.5 +/- 2.6) was significantly higher than that of the benign foci (1.8 +/- 2.1) (p < 0.0001). The IR score of the cancerous lesions significantly correlated with the Gleason score (p = 0.0135). Univariate and multivariate hazard analyses revealed significant correlations between elevated ERRalpha expression and poor cancer-specific survival (p = 0.0141 and 0.0367, respectively). The enhanced expression of ERRalpha might play a role in the development of human PC and serve as a significant prognostic factor for the disease.

Finasteride decreases the risk of prostatic intraepithelial neoplasia

PURPOSE

High grade prostatic intraepithelial neoplasia is likely a premalignant lesion of the prostate. Decreasing the frequency of high grade PIN may decrease the risk of prostate cancer. In the Prostate Cancer Prevention Trial we evaluated the impact of finasteride on the risk of a needle biopsy diagnosis of high grade prostatic intraepithelial neoplasia.

MATERIALS AND METHODS

The Prostate Cancer Prevention Trial was a randomized, placebo controlled clinical trial that enrolled 18,882 men without evidence of prostate cancer, prostate specific antigen less than 3.0 ng/ml and normal digital rectal examination, and randomized them to 5 mg finasteride daily or placebo. Subjects were followed for 7 years with biopsy recommended for prostate specific antigen greater than 4.0 ng/ml, adjusted in the finasteride group to achieve an equal number of biopsy recommendations or for abnormal digital rectal examination. All cancer-free subjects were recommended to undergo biopsy after 7 years on study. We evaluated the diagnosis of high grade prostatic intraepithelial neoplasia with or without concomitant prostate cancer in these 2 study groups.

RESULTS

The number of men evaluable for high grade prostatic intraepithelial neoplasia was 4,568 in the finasteride group and 4,886 in the placebo group. High grade prostatic intraepithelial neoplasia alone was diagnosed in 276 men (6.0%) in the finasteride group vs 347 (7.1%) in the placebo group (RR 0.85, 95% CI 0.73-0.99, p=0.04). High grade prostatic intraepithelial neoplasia accompanied by prostate cancer was diagnosed in 144 men (3.2%) in the finasteride group vs 223 (4.6%) in the placebo group (RR 0.69, 95% CI 0.56-0.85, p=0.0004). Finasteride significantly decreased the overall risk of high grade prostatic intraepithelial neoplasia (alone and with cancer) from 570 cases (11.7%) in the placebo group to 420 (9.2%) in the finasteride group (HR 0.79, 95% CI 0.70-0.89, p<0.001).

CONCLUSIONS

Finasteride significantly decreased the risk of high grade PIN. This observation may explain how finasteride decreased prostate cancer in the Prostate Cancer Prevention Trial, supporting the notion that high grade prostatic intraepithelial neoplasia is a premalignant lesion of the prostate, and it provides new information relevant to the consideration of finasteride for prostate cancer prevention.

Developmental estrogen exposures predispose to prostate carcinogenesis with aging

Prostate morphogenesis occurs in utero in humans and during the perinatal period in rodents. While largely driven by androgens, there is compelling evidence for a permanent influence of estrogens on prostatic development. If estrogenic exposures are abnormally high during the critical developmental period, permanent alterations in prostate morphology and function are observed, a process referred to as developmental estrogenization. Using the neonatal rodent as an animal model, it has been shown that early exposure to high doses of estradiol results in an increased incidence of prostatic lesions with aging which include hyperplasia, inflammatory cell infiltration and prostatic intraepithelial neoplasia or PIN, believed to be the precursor lesion for prostatic adenocarcinoma. The present review summarizes research performed in our laboratory to characterize developmental estrogenization and identify the molecular pathways involved in mediating this response. Furthermore, recent studies performed with low-dose estradiol exposures during development as well as exposures to environmentally relevant doses of the endocrine disruptor bisphenol A show increased susceptibility to PIN lesions with aging following additional adult exposure to estradiol. Gene methylation analysis revealed a potential epigenetic basis for the estrogen imprinting of the prostate gland. Taken together, our results suggest that a full range of estrogenic exposures during the postnatal critical period - from environmentally relevant bisphenol A exposure to low-dose and pharmacologic estradiol exposures - results in an increased incidence and susceptibility to neoplastic transformation of the prostate gland in the aging male which may provide a fetal basis for this adult disease.

Abarelix for injectable suspension: first-in-class gonadotropin-releasing hormone antagonist for prostate cancer

Abarelix, a gonadotropin-releasing hormone antagonist, with its indication for advanced symptomatic prostate cancer, represents the newest category of hormonal therapy introduced in the past 15 years. Results from Phase II and III clinical trials demonstrate the advantages of abarelix over commonly used luteinizing hormone-releasing hormone (LHRH) agonist therapy: abarelix does not cause a surge in serum testosterone that can precipitate a flare phenomenon or worsening of disease, particularly dangerous for patients with metastatic, symptomatic disease, and produces medical castration more quickly. Abarelix was also demonstrated to promptly and substantially reduce follicle-stimulating hormone levels to lower than LHRH agonist. Study results demonstrate effective anticancer responses during extended exposure to abarelix: improvements in pain score and/or analgesic use, improvements in urinary symptoms (including urinary catheter removal) and complete avoidance of bilateral orchiectomy for patients undergoing at least 12 weeks of treatment. In Phase III clinical trials, abarelix demonstrated a similar overall safety profile when compared with LHRH agonist monotherapy, and a superior safety profile when compared with LHRH agonist plus antiandrogen combination therapy. Abarelix patients experienced a greater incidence of immediate-onset systemic allergic reactions as compared with control arms.

An update on chemoprevention strategies in prostate cancer for 2006

PURPOSE OF REVIEW

An increasing volume of research has been directed at the prevention of prostate cancer. This review proposes to summarize the large trials, novel approaches and molecular mechanisms of effect published in 2004 and 2005.

RECENT FINDINGS

The impact of the Prostate Cancer Prevention Trial continues and subsequent articles have addressed the increase of high-grade prostate cancers detected in the finasteride arm of the trial, as well as the potential costs and benefits of extrapolating the findings to a public health campaign. Studies of risk have been published warning of excessive vitamin E and cyclooxygenase-2 inhibitor use in chemoprevention. Growing evidence supports the concept of chemopreventative agent combinations and further data on the roles of selenium, lycopene, soy, green tea, anti-inflammatories and statins in prostate-cancer prevention are presented.

SUMMARY

Level one evidence exists for the preventative effects of finasteride in prostate cancer. The evidence for other agents is less conclusive but a number of large-scale, appropriately designed trials will hopefully address some of the relevant issues in prostate-cancer prevention over the next decade.

Toremifene for the prevention of prostate cancer in men with high grade prostatic intraepithelial neoplasia: results of a double-blind, placebo controlled, phase IIB clinical trial

PURPOSE

A randomized, double-blind, dose finding, placebo controlled, parallel group clinical study was done to determine the incidence of prostate cancer in men with high grade prostatic intraepithelial neoplasia treated with toremifene.

MATERIALS AND METHODS

A total of 514 patients with high grade prostatic intraepithelial neoplasia and no evidence of prostate cancer on screening biopsy were randomized to 20, 40 or 60 mg toremifene, or placebo daily for 12 months. Patients underwent re-biopsy at 6 and 12 months.

RESULTS

The number of evaluable patients, that is those with 1 on study biopsy who were compliant, was 447. The cumulative risk of prostate cancer was decreased in patients on 20 mg toremifene compared with placebo (24.4% vs 31.2%, p <0.05). The annualized rate of prevention was 6.8 cancers per 100 men treated. In patients with no biopsy evidence of cancer at baseline and 6 months, the 12-month incidence of prostate cancer was decreased by 48.2% with 20 mg toremifene compared with placebo (9.1% vs 17.4%, p <0.05). The 20 mg dose was most effective but cumulative and 12-month incidences of prostate cancer were lower for each toremifene dose vs placebo with a cumulative risk of 29.2% and 28.1%, and a 12-month incidence of 14.3% and 13.0% for 40 and 60 mg, respectively. Gleason scores were similar across treatments. The overall incidence of drug related and serious adverse events did not differ between any of the toremifene groups and the placebo group.

CONCLUSIONS

Toremifene decreased the incidence of prostate cancer by 1 year and had a tolerability profile comparable to that of placebo in a high risk population.

Progress in chemoprevention drug development: the promise of molecular biomarkers for prevention of intraepithelial neoplasia and cancer--a plan to move forward

This article reviews progress in chemopreventive drug development, especially data and concepts that are new since the 2002 AACR report on treatment and prevention of intraepithelial neoplasia. Molecular biomarker expressions involved in mechanisms of carcinogenesis and genetic progression models of intraepithelial neoplasia are discussed and analyzed for how they can inform mechanism-based, molecularly targeted drug development as well as risk stratification, cohort selection, and end-point selection for clinical trials. We outline the concept of augmenting the risk, mechanistic, and disease data from histopathologic intraepithelial neoplasia assessments with molecular biomarker data. Updates of work in 10 clinical target organ sites include new data on molecular progression, significant completed trials, new agents of interest, and promising directions for future clinical studies. This overview concludes with strategies for accelerating chemopreventive drug development, such as integrating the best science into chemopreventive strategies and regulatory policy, providing incentives for industry to accelerate preventive drugs, fostering multisector cooperation in sharing clinical samples and data, and creating public-private partnerships to foster new regulatory policies and public education.

Toremifene--a promising therapy for the prevention of prostate cancer and complications of androgen deprivation therapy

Deregulation of the estrogen axis in humans prompts a series of tissue-specific events. In the breast and prostate, alterations in estrogen signalling lead to genotypic and phenotypic molecular alterations that result in dysplastic cellular appearance, deregulated cell growth and carcinoma. In bone, decreased estrogen leads to increased osteoclastogenesis and bone resorption, decreased bone mineral density and a significant fracture risk. Toremifene is a selective estrogen receptor modulator that exerts pharmacological activity in the breast, bone and prostate. An intense interest in developing this agent for prostate cancer chemoprevention is based on the reduction of premalignant and malignant prostate lesions in a transgenic model of prostate cancer. Biological and clinical activity was demonstrated in Phase II trials by the prevention of progression to prostate cancer in men with high-grade prostate intraepithelial neoplasia and through suppression of bone turnover biomarkers and increased bone mineral density in men on androgen deprivation therapy for prostate cancer.

Tumour plasticity and extravascular circulation in ECV304 human bladder carcinoma cells

BACKGROUND

The concepts of vasculogenic mimicry and mosaic vessels have been proposed as novel modes of tumour neovascularisation. However, the presence and significance of these types of neovascularisation remain unclear.

MATERIALS AND METHODS

ECV304 human bladder carcinoma cells were used to determine how tumour cells take part in tumour neovascularisation.

RESULTS

Subcutaneous ECV304 xenografts in mice showed various vessel types, including angiogenic vessels, tumour cell-related vessels and extracellular matrix networks. A tracer experiment demonstrated perfusion of beads in these structures. ECV304 cells, cultured on collagen I gels, formed tube networks with expressions of several endothelial-related markers. In coculture models of ECV304 cells and human umbilical vein endothelial cells, the two cells collaborated to form sprouts or networks.

CONCLUSION

ECV304 cells possess an endothelial character which confers the ability to mimic and collaborate with vascular endothelial cells and facilitates the acquisition of tumour microcirculation.

Ethnic and racial differences in prostate stromal estrogen receptor alpha

BACKGROUND

Prostate cancer incidence and mortality rates vary widely among individuals of different ethnic/racial groups. We identified a relationship between a subset of genes and race/ethnicity using gene expression profiling. Estrogen receptor alpha (ERalpha) was selected for confirmation due to its plausible biological role in cancer susceptibility.

METHODS

Quantitative polymerase chain reaction (Q-PCR) was used to verify gene expression results. Protein levels of ERalpha were determined by quantitative immunohistochemistry in a large-scale tissue microarray study (n = 183).

RESULTS

ERalpha was significantly higher in stroma of Hispanic and Asian men than in Caucasian (P < 0.0001) and African American men (P < 0.0002), who are at higher risk for prostate cancer. In addition, large differences were seen in Q-PCR levels of ERalpha in prostate tissues of organ donors 16-29 years old who had no evidence of cancer.

CONCLUSIONS

ERalpha exhibits variable expression in men of difference racial/ethnic background. Understanding the molecular basis for these differences may form the basis for prostate cancer prevention strategies with widespread public health impact.

Role of estrogens in development of prostate cancer

Estrogens have previously been extensively used in prostate cancer treatment. Serious side effects, primarily in cardiovascular system have, however, limited their use. The therapeutic effect of estrogen in preventing prostate cancer growth was mainly obtained indirectly by feedback inhibition of the hypothalamic release of LRH leading to lowered serum androgen levels and castration like effects. Prostate tissue is also most probably a target for direct regulation by estrogens. Prostate contains estrogen receptor alpha (ERalpha) and beta (ERbeta), which are localized characteristically in stroma and epithelium, respectively. The physiological function of these receptors is not known but there is evidence of the role of estrogens in prostatic carcinogenesis. Developing prostate seems particularly sensitive to increased level of endogenous and/or exogenous estrogens. Perinatal or neonatal exposure of rats and mice to estrogens leads to "imprinting" of prostate associated with increased proliferation, inflammation and dysplastic epithelial changes later in life. Prolonged treatment of adult rodents with estrogens along with androgens also leads to epithelial metaplasia, PIN-like lesions and even adenocarcinoma of prostate speaking for the role of estrogen in prostate cancer development. Recent results concerning antiestrogen inhibition of prostate cancer development beyond PIN-type lesions in transgenic mouse models further suggests a role for estrogens in prostate cancer progression. These results also suggest that direct inhibition of estrogen action at the level of prostate tissue may provide an important novel principle of development of prostate cancer therapies.