Medical castration with LHRH agonists: 25 years later with major benefits achieved on survival in prostate cancer

Evaluation of the criteria for renewal of LHRH agonists in patients with prostate cancer: results of the ANAREN Study

Introduction

Injectable extended-release formulations of luteinizing hormone-releasing hormone agonists (LHRHa) have simplified the treatment of prostate cancer with a satisfactory level of androgen castration. This study aims to determine the percentage of patients whose initial LHRHa prescription was renewed during follow-up, how many changed formulation and how their quality of life evolved.

Methods

This is an observational, prospective, multicentre study of men with prostate cancer who were to receive treatment with LHRHa (triptorelin every 3 or 6 months, leuprorelin every 3 or 6 months, or goserelin every 3 months) for 24 months. The treatment used was recorded and quality of life was assessed (QLQ-PR25 questionnaire) at four follow-up visits.

Results

A total of 497 men (median age 75 years) were evaluated. The median exposure to LHRHa was 24 months. The initial prescription was renewed in 95.7% at follow-up 1 and 75% at follow-up 4. The main reason for changing from a 6-month to a 3-month formulation was a preference for sequential treatment (according to the investigator) and to see the physician more frequently (according to the patient). The main reason for switching from the 3-month to 6-month formulation was simplification of treatment (according to the investigator) and for convenience (according to the patient). Findings in the QLQ-PR25 questionnaire revealed no changes in urinary or bowel symptoms, though an improvement in sexual activity was reported. Practically all investigators and patients were satisfied/very satisfied with the treatment.

Conclusion

Changes in formulation were scarce and generally justified by convenience factors or personal preferences. Patients maintained a good health status, with a high rate of retention of LHRHa treatment.

Clinical Trial Registration

Study number: A-ES-52014-224.A plain language summary is provided as supplementary material (available at: https://www.drugsincontext.com/wp-content/uploads/2024/05/dic.2024-2-2-Suppl.pdf).

Testosterone castration levels in patients with prostate cancer: Is there a difference between GnRH agonist and GnRH antagonist? Primary results of an open-label randomized control study

PURPOSE

To compare testosterone castration levels between patients treated with the gonadotropin-releasing hormone (GnRH) antagonist, degarelix, and GnRH agonist.

MATERIALS AND METHODS

Patients with prostate cancer (PCa) of a single outpatient clinic were randomized (2:1) to receive degarelix (group A) or GnRH agonist (group B). The study evaluated testosterone and prostate-specific antigen (PSA) levels, patients' age, Gleason score and the presence of metastases (nodal or bone). Testosterone and PSA levels were measured at 1st, 6th, 12th, and 18th months. Mann-Whitney test and Spearman correlation were used to investigate independent variable while standard multiple regression was performed to explore statistically significant correlations. Kruskal-Wallis test was used to compare testosterone levels at follow-up.

RESULTS

The study included 168 patients, 107 in group A and 61 in group B. Testosterone levels at 1st month were significantly lower in patients under GnRH antagonist than those receiving GnRH agonist (group A: 22 ng/dL vs. group B: 29 ng/dL, p=0.011). However, PSA values did not differ significantly between groups (group A: 0.130 ng/mL vs. group B: 0.067 ng/mL, p=0.261). In multivariate analysis, treatment with degarelix was an independent factor of lower testosterone levels at 1st month (p=0.013). Comparison of testosterone levels at 6, 12, and 18 months did not reveal any significant difference within each group.

CONCLUSIONS

In patients with PCa who are candidates for androgen deprivation therapy, the administration of GnRH antagonist seems to achieve significantly lower testosterone levels compared to treatment with GnRH agonist at 1st month of treatment.

Cancer-biomarkers associated with sex hormone receptors and recent therapeutic advancements: a comprehensive review

Hormones and its regulation plays vital role in causing breast, prostate, ovarian and endometrial cancers collectively known as hormone-sensitive cancers. This review discusses the various functions of the sex hormones and the biological pathways involved in causing hormone-associated cancer under differential regulation. We have also attempted to explore the biomarkers associated with the cancers and the current therapeutic availability to treat such cancers. Among various sex hormones such as estrogen, progesterone and androgen, estrogen the female sex hormone and its receptor had a major contribution in causing cancer and hence are considered a predominant target in treating the associated cancers. Other hormones and receptors such a androgen, progesterone, and their respective receptors were also reported to have a significant correlation in causing cancers. Apart from these receptors certain enzymes that act as precursors or as promoters are also targeted for treatment strategies. The drugs commonly used belong to the selective drug classes such as selective estrogen receptor modulators and selective progesterone receptor modulators. In the case of androgen regulation androgen deprivation therapies are practiced. It is also suggested that the use of natural substances to treat cancer could prevent resistance and reduce side effects. Identification of significant targets and the discovery of many efficient drugs shall be possible in the future with better understanding of hormone regulation and its influence on cancer causative mechanisms.

Preclinical models of prostate cancer - modelling androgen dependency and castration resistance in vitro, ex vivo and in vivo

Prostate cancer is well known to be dependent on the androgen receptor (AR) for growth and survival. Thus, AR is the main pharmacological target to treat this disease. However, after an initially positive response to AR-targeting therapies, prostate cancer will eventually evolve to castration-resistant prostate cancer, which is often lethal. Tumour growth was initially thought to become androgen-independent following treatments; however, results from molecular studies have shown that most resistance mechanisms involve the reactivation of AR. Consequently, tumour cells become resistant to castration - the blockade of testicular androgens - and not independent of AR per se. However, confusion still remains on how to properly define preclinical models of prostate cancer, including cell lines. Most cell lines were isolated from patients for cell culture after evolution of the tumour to castration-resistant prostate cancer, but not all of these cell lines are described as castration resistant. Moreover, castration refers to the blockade of testosterone production by the testes; thus, even the concept of "castration" in vitro is questionable. To ensure maximal transfer of knowledge from scientific research to the clinic, understanding the limitations and advantages of preclinical models, as well as how these models recapitulate cancer cell androgen dependency and can be used to study castration resistance mechanisms, is essential.

Conventional androgen deprivation therapy is associated with an increased risk of fracture in advanced prostate cancer, a nationwide population-based study

PURPOSE

Androgen deprivation therapy (ADT) is the standard of care in advanced prostate cancer. We conducted a Taiwan National Health Insurance Research Database (NHIRD) study to evaluate the association between ADT and fracture risk in patient with prostate cancer in Taiwan.

METHODS

Between 2001 and 2008, data from the Taiwan NHIRD was collected. We separated newly diagnosed prostate cancer patients into four groups: the injection of gonadotropin-releasing hormone agonists and antagonists group, the orchiectomy group, the oral antiandorgens group and the radical prostatectomy only group. A non-cancer matched control group was also assigned for comparison. T tests, chi-squared tests, multivariate Cox proportional hazard regression were performed. A subsequent fracture event was defined according to the appropriate diagnosis codes (ICD9-CM 800-829) with hospitalization. Patients with fracture before their diagnosis with prostate cancer were excluded.

RESULTS

Overall, 22517 newly diagnosed patients with prostate cancer were enrolled in the study. After exclusion criteria were applied, 13321 patients were separated into the injection group (5020 subjects), the orchiectomy group (1193 subjects), the oral group (6059 subjects) and the radical prostatectomy only group (1049 subjects). The mean age of the overall study population was 74.4 years. Multi-variant analysis disclosed a significantly increased risk of fracture in the injection group, the orchiectomy group, and the oral group (hazard ratio [HR] = 1.55, 95%, confidence interval [CI] 1.36 to 1.76, p<0.001, HR = 1.95, 95%, CI 1.61 to 2.37, p<0.001, HR = 1.37, 95%, CI 1.22 to 1.53, p<0.001, respectively). In contrast, a significantly decreased fracture risk was noted in the radical prostatectomy only group (HR = 0.51, 95%, CI 0.35 to 0.74, p = 0.001). Patients receiving osteoporosis medication had a significantly decreased fracture risk (HR = 0.26, 95%, CI 0.19-0.37, p<0.001).

CONCLUSIONS

ADT is associated with an increased risk of fracture. For patients receiving long-term prostate cancer castration therapy, doctors should always keep this complication in mind and arrange proper monitoring and provide timely osteoporosis medication.

The proteasome inhibitor, bortezomib, induces prostate cancer cell death by suppressing the expression of prostate-specific membrane antigen, as well as androgen receptor

The progression of primary prostate cancer (PC) is dependent on the androgen receptor (AR) and prostate‑specific membrane antigen (PSMA). Furthermore, the growth of PC cells is terminated with the downregulation of both AR and PSMA. In our preliminary experiments, it was also found that bortezomib (BZ; PS‑341) that inhibits 26S proteasome activity, acts as a downregulator of both PSMA and AR. In addition to evaluating the effects of BZ on protein expression, the present study evaluated and compared the anticancer effects of BZ on the growth of cells treated with BZ, docetaxel (DOC), or a combination of both. Western blot analysis was used to examine the expression levels of AR and PSMA. The knockdown effect of small interfering RNA (siRNA) and the drugs on the expression of either AR or PSMA was also evaluated. An MTT assay was performed in order to evaluate the inhibitory effects of the drugs on PC cells. The cell cycles were analyzed, and apoptotic cells were detected. The downregulation of AR and PSMA was observed using siRNA specific to AR or PSMA, and the inhibition of PSMA, as well as that of AR severely suppressed the growth of PC cells. The inhibitory effect of BZ alone on PSMA expression was similar to that of both AR‑ and PSMA‑specific siRNA, and this drug also induced the downregulation of AR and PSMA in PC cells. This phenomenon was confirmed even in cells transfected to overexpress PSMA. The apoptosis‑promoting effect of BZ on the cells was similar to that observed with BZ plus DOC, and more potent than that of DOC alone. BZ had the same inhibitory effect on the expression of AR and PSMA as did siRNA specific to AR or PSMA. On the whole, the findings of this study indicate that BZ may prove to be a promising chemotherapeutic agent and may be used as a molecularly targeted drug in the treatment of PC.

Practical differences between luteinizing hormone-releasing hormone agonists in prostate cancer: perspectives across the spectrum of care

BACKGROUND

Androgen deprivation therapy (ADT) with luteinizing hormone-releasing hormone (LHRH) agonists is well established for the treatment of men with metastatic prostate cancer. As clear differences in efficacy, safety, or tolerability between the available LHRH agonists are lacking, the healthcare management team needs to look to practical differences between the formulations when selecting therapy for their patients. Moreover, as the economic burden of prostate cancer rises alongside earlier diagnosis and improved survival, the possibility for cost savings by using products with specific features is growing in importance.

METHODS

A review was conducted to summarize the information on the different LHRH agonist formulations currently available and offer insight into their relative benefits and disadvantages from the perspectives of physicians, a pharmacist, and a nurse.

RESULTS

The leuprorelin acetate and goserelin acetate solid implants have the advantage of being ready to use with no requirement for refrigeration, whereas powder and microsphere formulations have to be reconstituted and have specific storage or handling constraints. The single-step administration of solid implants, therefore, has potential to reduce labor time and associated costs. Dosing frequency is another key consideration, as administering the injection provides an opportunity for face-to-face interaction between the patient and healthcare professionals to ensure therapy is optimized and give reassurance to patients. Prostate cancer patients are reported to prefer 3- or 6-monthly dosing, which aligns with the monitoring frequency recommended in European Association of Urology guidelines and has been shown to result in reduced annual costs compared with 1-month formulations.

CONCLUSIONS

A number of practical differences exist between the different LHRH agonist preparations available, which may impact on clinical practice. It is important for healthcare providers to be aware and carefully consider these differences when selecting treatments for their prostate cancer patients.

Treatment patterns and trends in patients dying of prostate cancer in Quebec: a population-based study

INTRODUCTION

Since just after the year 2000 in Quebec, the management of metastatic castration-resistant prostate cancer (mcrpc) has evolved considerably, with the inclusion of docetaxel-based chemotherapy, bone-targeted therapies (zoledronic acid and denosumab), and more recently, abiraterone, enzalutamide, and cabazitaxel for docetaxel-refractory patients. In the present study, we aimed to analyze contemporary mcrpc management patterns and therapy utilization trends in Quebec.

METHODS

The study cohort consisted of patients dying of prostate cancer (pca) between January 2001 and December 2013, selected from Quebec public health care insurance databases. Patient selection was based on death from a pca-related cause or therapy used according to the Canadian Urological Association guidelines on mcrpc management. Treatments included chemotherapy (mitoxantrone before 2005 and docetaxel after 2005), abiraterone, bone-targeted therapy (zoledronic acid or denosumab, or both), and palliative radiation therapy (rt). During the study period, neither enzalutamide nor cabazitaxel was publicly reimbursed in Quebec, and as a result, no capture of their use was possible for this study. Multivariate logistic regression was used to identify factors associated with the probability of receiving chemotherapy, bone-targeted therapies, and palliative rt before death from pca.

RESULTS

Overall, the database search identified 3106 patients who died of pca between January 2001 and December 2013. Median age of death was 78 years. Of those 3106 patients, just 2568 (83%) received mcrpc-specific treatments: chemotherapy, abiraterone, palliative rt, or bone-targeted therapy; the other 17% of the patients were managed solely with maximum androgen blockade (androgen deprivation therapy plus anti-androgens) despite a record of pca-related death. Logistic regression analyses indicate that patients dying after 2005 were more likely to have received chemotherapy [odds ratio (or): 1.51; 95% ci: 1.22 to 1.85] and bone-targeted therapy (or: 1.97; 95% ci: 1.64 to 2.37). Age was a significant predictor for the use of chemotherapy, bone-targeted therapy, and palliative rt (ors in the range 0.96-0.98, p < 0.05).

CONCLUSIONS

Patient age seems to be a strong determinant in the of selection mcrpc therapy, affecting the probability of the use of chemotherapy, bone-targeted therapy, or palliative rt. Although chemotherapy is still used only in a small percentage of patients, the introduction of new therapies-such as bone-targeted therapy, docetaxel, and abiraterone-affected treatment selection over time. The availability of enzalutamide since February 2014 will likely produce additional changes in mcrpc management.

Patients receiving androgen deprivation therapy for prostate cancer have an increased risk of depressive disorder

Androgen deprivation therapy (ADT) results in testosterone suppression, a hypothesized mechanism linking ADT to depressive symptoms. This study investigated the relationship between ADT and the risk of subsequently being diagnosed with depressive disorder (DD) during a 3-year follow-up period. The patient sample for this population-based, retrospective cohort study was retrieved from the Taiwan Longitudinal Health Insurance Database 2005. We included all 1714 patients aged over 40 years with a first-time diagnosis of prostate cancer (PC) during 2001 to 2010 who did not have an orchiectomy. Among them, we defined 868 patients who received ADT during the 3-year follow-up period as the study group, and 846 patients who did not receive ADT as the comparison group. The incidence rates of DD per 1000 person-years were 13.9 (95% confidence interval (CI): 9.5~19.6) and 6.7 (95% CI: 3.7~11.0), respectively. Cox proportional hazard regressions showed that the adjusted hazard ratio for DD for ADT recipients was 1.93 (95% CI: 1.03~3.62) relative to the comparison group. This study presents epidemiological evidence of an association between ADT and a subsequent DD diagnosis.

Androgen deprivation increases the risk of fracture in prostate cancer patients: a population-based study in Chinese patients

Androgen deprivation therapy (ADT) or orchiectomy is associated with an increased risk of osteoporosis or fracture. In this nationwide database analysis, we found that ADT or orchiectomy increased the risk of fracture in Chinese patients with prostate cancer. However, the magnitude of increase is seemingly not as large as that in Western populations.

INTRODUCTION

ADT using gonadotropin-releasing hormone (GnRH) agonists or orchiectomy is associated with an increased risk of osteoporosis or fracture. To investigate the effects of ADT duration or orchiectomy on any type of fracture in Asian patients with prostate cancer, we conducted this retrospective analysis using a nationwide database in Taiwan.

METHODS

We included 17,359 subjects who were newly diagnosed with prostate cancer between January 1, 1998, and December 31, 2007. The risk of first fracture was our primary endpoint.

RESULTS

The rates of fracture from 12 months after prostate cancer diagnosis until the last follow-up date were 8.7 % for all patients, 7.1 % for patients who did not receive ADT or orchiectomy, 9.8 % for patients who received ADT, and 14.4 % for patients who received orchiectomy with or without ADT (P < 0.0001). In a Cox proportional hazard analysis, the relative risk of fracture increased steadily with the number of doses of GnRH agonists received during the first year after cancer diagnosis and with dose density. A significant hazard ratio was observed in patients who received at least nine doses within 1 year after diagnosis and in those whose dose density exceeded two doses per year. Age greater than or equal to 65 years was associated with a significantly lower risk of fracture.

CONCLUSION

ADT or orchiectomy increases the risk of fracture in Chinese patients with prostate cancer. However, the magnitude of this increase is seemingly not as large as that in Western populations.

Drug costs in the management of metastatic castration-resistant prostate cancer in Canada

BACKGROUND

For Canadian men, prostate cancer (PCa) is the most common cancer and the 3rd leading cause of cancer mortality. Men dying of PCa do so after failing castration. The management of metastatic castration-resistant prostate cancer (mCRPC) is complex and the associated drug treatments are increasingly costly. The objective of this study was to estimate the cost of drug treatments over the mCRPC period, in the context of the latest evidence-based approaches.

METHODS

Two Markov models with Monte-Carlo microsimulations were developed in order to simulate the management of the disease and to estimate the cost of drug treatments in mCRPC, as per Quebec's public healthcare system. The models include recently approved additional lines of treatment after or before docetaxel (i.e. abiraterone and cabazitaxel). Drug exposure and survival were based on clinical trial results and clinical practice guidelines found in a literature review. All costs were assigned in 2013 Canadian dollars ($). Only direct drug costs were estimated.

RESULTS

The mean cost of mCRPC drug treatments over an average period of 28.1 months was estimated at $48,428 per patient (95% Confidence Interval: $47,624 to $49,232). The mean cost increased to $104,071 (95% CI: $102,373 - $105,770) per patient when one includes abiraterone initiation prior to docetaxel therapy. Over the mCRPC period, luteinizing hormone-releasing hormone agonists (LHRHa) prescribed to maintain castrate testosterone levels accounted for 20.4% of the total medication cost, whereas denosumab prescribed to decrease bone-related events accounted for 30.5% of costs. When patients received cabazitaxel in sequence after abiraterone and docetaxel, the mCRPC medications cost per patient per month increased by 60.2%. The total cost of medications for the treatment of each annual Canadian cohort of 4,000 mCRPC patients was estimated at $ 193.6 million to $416.3 million.

CONCLUSIONS

Our study estimates the direct drug costs associated with mCRPC treatments in the Canadian healthcare system. Recently identified effective yet not approved therapies will become part of the spectrum of mCRPC treatments, and may potentially increase the cost.

Six-month leuprorelin acetate depot formulations in advanced prostate cancer: a clinical evaluation

For nearly three decades, gonadotropin-releasing hormone (GnRH) agonists, particularly leuprorelin acetate (LA), have served as an important part of the treatment armamentarium for prostate cancer. The introduction of LA depot formulations provided a significant improvement in the acceptance of this therapy; however, their indicated treatment duration of 1 to 4 months was still not long enough to satisfy all medical needs. For this reason some manufacturers developed new injectable formulations that provide testosterone suppression for 6 months. This review article assesses key publications in order to compare these long-acting, commercially available, LA depot formulations and their clinical performance. The literature search identified 14 publications; by excluding reviews, duplications, and non-English articles, only three original papers describing clinical trial remained for review: two focused on microsphere-based LA formulations with either a 30 mg or 45 mg dose and one focused on a gel-based leuprorelin acetate with a 45 mg dose. All products were tested in individual clinical trials and have demonstrated their efficacy and safety.

GnRH receptors in cancer: from cell biology to novel targeted therapeutic strategies

The crucial role of pituitary GnRH receptors (GnRH-R) in the control of reproductive functions is well established. These receptors are the target of GnRH agonists (through receptor desensitization) and antagonists (through receptor blockade) for the treatment of steroid-dependent pathologies, including hormone-dependent tumors. It has also become increasingly clear that GnRH-R are expressed in cancer tissues, either related (i.e. prostate, breast, endometrial, and ovarian cancers) or unrelated (i.e. melanoma, glioblastoma, lung, and pancreatic cancers) to the reproductive system. In hormone-related tumors, GnRH-R appear to be expressed even when the tumor has escaped steroid dependence (such as castration-resistant prostate cancer). These receptors are coupled to a G(αi)-mediated intracellular signaling pathway. Activation of tumor GnRH-R by means of GnRH agonists elicits a strong antiproliferative, antimetastatic, and antiangiogenic (more recently demonstrated) activity. Interestingly, GnRH antagonists have also been shown to elicit a direct antitumor effect; thus, these compounds behave as antagonists of GnRH-R at the pituitary level and as agonists of the same receptors expressed in tumors. According to the ligand-induced selective-signaling theory, GnRH-R might assume various conformations, endowed with different activities for GnRH analogs and with different intracellular signaling pathways, according to the cell context. Based on these consistent experimental observations, tumor GnRH-R are now considered a very interesting candidate for novel molecular, GnRH analog-based, targeted strategies for the treatment of tumors expressing these receptors. These agents include GnRH agonists and antagonists, GnRH analog-based cytotoxic (i.e. doxorubicin) or nutraceutic (i.e. curcumin) hybrids, and GnRH-R-targeted nanoparticles delivering anticancer compounds.

Versatile virus-like particle carrier for epitope based vaccines

BACKGROUND

Recombinant proteins and in particular single domains or peptides are often poorly immunogenic unless conjugated to a carrier protein. Virus-like-particles are a very efficient means to confer high immunogenicity to antigens. We report here the development of virus-like-particles (VLPs) derived from the RNA bacteriophage AP205 for epitope-based vaccines.

METHODOLOGY/PRINCIPAL FINDINGS

Peptides of angiotensin II, S.typhi outer membrane protein (D2), CXCR4 receptor, HIV1 Nef, gonadotropin releasing hormone (GnRH), Influenza A M2-protein were fused to either N- or C-terminus of AP205 coat protein. The A205-peptide fusions assembled into VLPs, and peptides displayed on the VLP were highly immunogenic in mice. GnRH fused to the C-terminus of AP205 induced a strong antibody response that inhibited GnRH function in vivo. Exposure of the M2-protein peptide at the N-terminus of AP205 resulted in a strong M2-specific antibody response upon immunization, protecting 100% of mice from a lethal influenza infection.

CONCLUSIONS/SIGNIFICANCE

AP205 VLPs are therefore a very efficient and new vaccine system, suitable for complex and long epitopes, of up to at least 55 amino acid residues in length. AP205 VLPs confer a high immunogenicity to displayed epitopes, as shown by inhibition of endogenous GnRH and protective immunity against influenza infection.

Hormonal therapy of prostate cancer

Of all cancers, prostate cancer is the most sensitive to hormones: it is thus very important to take advantage of this unique property and to always use optimal androgen blockade when hormone therapy is the appropriate treatment. A fundamental observation is that the serum testosterone concentration only reflects the amount of testosterone of testicular origin which is released in the blood from which it reaches all tissues. Recent data show, however, that an approximately equal amount of testosterone is made from dehydroepiandrosterone (DHEA) directly in the peripheral tissues, including the prostate, and does not appear in the blood. Consequently, after castration, the 95-97% fall in serum testosterone does not reflect the 40-50% testosterone (testo) and dihydrotestosterone (DHT) made locally in the prostate from DHEA of adrenal origin. In fact, while elimination of testicular androgens by castration alone has never been shown to prolong life in metastatic prostate cancer, combination of castration (surgical or medical with a gonadotropin-releasing hormone (GnRH) agonist) with a pure anti-androgen has been the first treatment shown to prolong life. Most importantly, when applied at the localized stage, the same combined androgen blockade (CAB) can provide long-term control or cure of the disease in more than 90% of cases. Obviously, since prostate cancer usually grows and metastasizes without signs or symptoms, screening with prostate-specific antigen (PSA) is absolutely needed to diagnose prostate cancer at an 'early' stage before metastasis occurs and the cancer becomes non-curable. While the role of androgens was believed to have become non-significant in cancer progressing under any form of androgen blockade, recent data have shown increased expression of the androgen receptor (AR) in treatment-resistant disease with a benefit of further androgen blockade. Since the available anti-androgens have low affinity for AR and cannot block androgen action completely, especially in the presence of increased AR levels, it becomes important to discover more potent and purely antagonistic blockers of AR. The data obtained with compounds under development are promising. While waiting for this (these) new anti-androgen(s), combined treatment with castration and a pure anti-androgen (bicalutamide, flutamide or nilutamide) is the only available and the best scientifically based means of treating prostate cancer by hormone therapy at any stage of the disease with the optimal chance of success and even cure in localized disease.

Regulation of cell cycle and RNA transcription genes identified by microarray analysis of PC-3 human prostate cancer cells treated with luteolin

Prostate cancer is the second leading cause of cancer-related deaths in men in the United States. Our previous studies have shown that ligands for the nuclear type II [(3)H]estradiol binding site such as luteolin significantly inhibit prostate cancer cells in vitro and in vivo; however, the role of these ligands in cell growth and proliferation is poorly understood. In order to further elucidate the molecular mechanism through which luteolin exerts its effects on PC-3 cells, cRNA microarray analyses was performed on 38,500 genes to determine the genes altered by luteolin treatment. The expression of 3331 genes was changed greater than 1.2-fold after luteolin treatment. Analysis of the altered genes identified two pathways that were significantly affected by luteolin. The Cell Cycle Pathway contained 22 down-regulated genes (including polo-like kinase 1, cyclin A2, cyclin E2 and proliferation cell nuclear antigen) and one up-regulated gene (cyclin-dependent kinase inhibitor 1B). In addition, 13 genes were down-regulated by luteolin in the RNA Transcription Pathway. Real-time polymerase chain reactions and western blots verified the observations from the microarray. In addition, two synthetic, chemically distinct type II ligands, ZN-2 and BMHPC, mimicked the effects of luteolin on gene expression at the mRNA and protein level in PC-3 cells. Finally, chromatin immunoprecipitation assays indicated that luteolin exerts its effects on genes by altering the acetylation state of promoter-associated histones. Taken together, the data suggest that type II ligands inhibit cell growth and proliferation through epigenetic control of key genes involved in cell cycle progression and RNA transcription.

In vivo evaluation and in vitro metabolism of leuprolide in mice--mass spectrometry-based biomarker measurement for efficacy and toxicity

The study of pharmacologically active peptides is central for the understanding of cancer and the development of novel therapeutic approaches. In this context, both qualitative and quantitative determination of bioactive peptides in biological fluids/tissues and their effect on endogenous factors (e.g. hormones) are of great importance. A mass spectrometry-based approach was developed and applied towards the measurement of leuprolide, a peptide drug for the treatment of prostate cancer, in mouse plasma. High-pressure liquid chromatography coupled to a hybrid quadrupole linear ion trap (QqLIT) mass spectrometer, a platform that combines the benefits of triple QqLIT instruments, was employed for the study. Using the described methodology, we established that picomolar concentrations of leuprolide could be measured in mouse plasma (limit of quantification of 0.1 ng/ml). In order to optimize pharmacokinetic properties of analogs of leuprolide, a facile in vivo mouse model was developed and leuprolide concentrations were determined in mouse plasma following intraperitoneal administration. In the same animal model, we demonstrated the versatility of the described MS-based approach by the determination of plasma concentrations of testosterone, an established biomarker for the treatment of prostate cancer. Following dosing with leuprolide, circulating testosterone was increased significantly in comparison to vehicle-treated mice. Finally, in vitro metabolism of leuprolide was evaluated by incubation of leuprolide with mouse kidney membranes, followed by identification of major metabolites by MS. Such studies provide the framework for future evaluation of novel leuprolide analogs with potential therapeutic advantages.

1alpha,25-Dihydroxyvitamin D3 down-regulates expression of prostate specific membrane antigen in prostate cancer cells

BACKGROUND

Prostate specific membrane antigen (PSMA) expression correlates with prostate cancer grade and is increased in hormone-refractory prostate cancer. The increased expression of PSMA following androgen deprivation therapy may be a consequence of the down-regulation of PSMA expression by androgen. Moreover, 1alpha,25-dihydroxyvitamin D3 (1,25-VD) has been shown to suppress prostate cancer progression as well as cell motility and invasion. Since PSMA is positively correlated with both of these characteristics, we hypothesized that 1,25-VD would regulate PSMA expression.

METHODS

LNCaP prostate cancer cells were treated with 1,25-VD, followed by analysis of cell surface PSMA expression. The PSMA enhancer, located within the third intron of the PSMA gene, was cloned into a reporter vector and regulation by 1,25-VD was investigated. The role of the androgen receptor (AR) in 1,25-VD mediated suppression of PSMA expression was examined using Casodex and AR specific siRNA.

RESULTS

Surface expression of PSMA was significantly decreased in a dose-dependent manner by 10 nM 1,25-VD or greater. Regulation by 1,25-VD occurred at the level of the PSMA enhancer. Over-expression of the vitamin D receptor (VDR) also decreased expression of PSMA. Additionally, suppression of AR translation using siRNA technology blocked the suppressive effect of 1,25-VD on PSMA expression, however inhibition of PSMA expression by 1,25-VD occurred in the absence of androgens.

CONCLUSIONS

Suppression of PSMA by 1,25-VD occurs at the level of the PSMA enhancer and is elevated by over-expression of the VDR. This regulation involves the AR, but is not dependent on the presence of androgens.

Optimizing outcomes and quality of life in the hormonal treatment of prostate cancer

We review the effectiveness of androgen-deprivation therapy (ADT) in the management of prostate cancer, and the effect that this treatment has on a patient's quality of life (QoL), based on discussions held at a European symposium on the management of prostate cancer. The overall QoL is reduced in asymptomatic men, and there are known decreases in cognitive function, self-esteem, libido and sexual function. Hot flashes are also a frequent problem. Prolonged ADT can lead to osteoporosis and subsequently fractures. Various effective methods exist to manage and minimize these side-effects; some are specific to the side-effect, whereas other more general methods include lifestyle changes, specific drugs and added hormonal manipulations. Intermittent ADT for patients taking luteinizing hormone-releasing hormone agonists offers a promising method to reduce adverse effects, and possibly increases the time to androgen independence. Initial studies indicate that prostate-specific antigen-based progression with intermittent ADT is similar to that seen with continuous ADT, but there is a reduction in side-effects, leading to an improvement in QoL.