Increased Androgen Receptor and Remodeling in the Prostatic Stroma After the Inhibition of 5-Alpha Reductase and Aromatase in Gerbil Ventral Prostate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Finasteride Inhibits Human Prostate Cancer Cell Invasion through MMP2 and MMP9 Downregulation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Surrogate endpoints for prostate cancer-specific mortality after radiotherapy and androgen suppression therapy in men with localised or locally advanced prostate cancer: an analysis of two randomised trials

Background Androgen suppression therapy and radiotherapy are used to treat locally advanced prostate cancer. 3 years of androgen suppression confers a small survival benefit compared with 6 months of therapy in this setting, but is associated with more toxic effects. Early identification of men in whom radiotherapy and 6 months of androgen suppression is insufficient for cure is important. Thus, we assessed whether prostate-specific antigen (PSA) values can act as an early surrogate for prostate cancer-specific mortality (PCSM). Methods We systematically reviewed randomised controlled trials that showed improved overall and prostate cancer-specific survival with radiotherapy and 6 months of androgen suppression compared with radio therapy alone and measured lowest PSA concentrations (PSA nadir) and those immediately after treatment (PSA end). We assessed a cohort of 734 men with localised or locally advanced prostate cancer from two eligible trials in the USA and Australasia that randomly allocated participants between Feb 2, 1996, and Dec 27, 2001. We used Prentice criteria to assess whether reported PSA nadir or PSA end concentrations of more than 0.5 ng/mL were surrogates for PCSM. Findings Men treated with radiotherapy and 6 months of androgen suppression in both trials were significantly less likely to have PSA end and PSA nadir values of more than 0.5 ng/mL than were those treated with radiotherapy alone (p<0.0001). Presence of candidate surrogates (ie, PSA end and PSA nadir values >0.5 ng/mL) alone and when assessed in conjunction with the randomised treatment group increased risk of PCSM in the US trial (PSA nadir p=0.0016; PSA end p=0.017) and Australasian trial (PSA nadir p<0.0001; PSA end p=0.0012). In both trials, the randomised treatment group was no longer associated with PCSM (p >= 0.20) when the candidate surrogates were included in the model. Therefore, both PSA metrics satisfied Prentice criteria for surrogacy. Interpretation After radiotherapy and 6 months of androgen suppression, men with PSA end values exceeding 0.5 ng/mL should be considered for long-term androgen suppression and those with localised or locally advanced prostate cancer with PSA nadir values exceeding 0.5 ng/mL should be considered for inclusion in randomised trials investigating the use of drugs that have extended survival in castration-resistant metastatic prostate cancer.

FOXA1 Promotes Tumor Progression in Prostate Cancer and Represents a Novel Hallmark of Castration-Resistant Prostate Cancer

Forkhead box protein A1 (FOXA1) modulates the transactivation of steroid hormone receptors and thus may influence tumor growth and hormone responsiveness in prostate cancer. We therefore investigated the correlation of FOXA1 expression with clinical parameters, prostate-specific antigen (PSA) relapse-free survival, and hormone receptor expression in a large cohort of prostate cancer patients at different disease stages. FOXA1 expression did not differ significantly between benign glands from the peripheral zone and primary peripheral zone prostate carcinomas. However, FOXA1 was overexpressed in metastases and particularly in castration-resistant cases, but was expressed at lower levels in both normal and neoplastic transitional zone tissues. FOXA1 levels correlated with higher pT stages and Gleason scores, as well as with androgen (AR) and estrogen receptor expression. Moreover, FOXA1 overexpression was associated with faster biochemical disease progression, which was pronounced in patients with low AR levels. Finally, siRNA-based knockdown of FOXA1 induced decreased cell proliferation and migration. Moreover, in vitro tumorigenicity was inducible by ARs only in the presence of FOXA1, substantiating a functional cooperation between FOXA1 and AR. In conclusion, FOXA1 expression is associated with tumor progression, dedifferentiation of prostate cancer cells, and poorer prognosis, as well as with cellular proliferation and migration and with AR signaling. These findings suggest FOXA1 overexpression as a novel mechanism inducing castration resistance in prostate cancer.

Stem-like cells with luminal progenitor phenotype survive castration in human prostate cancer

Castration is the standard therapy for advanced prostate cancer (PC). Although this treatment is initially effective, tumors invariably relapse as incurable, castration-resistant PC (CRPC). Adaptation of androgen-dependent PC cells to an androgen-depleted environment or selection of pre-existing, CRPC cells have been proposed as mechanisms of CRPC development. Stem cell (SC)-like PC cells have been implicated not only as tumor initiating/maintaining in PC but also as tumor-reinitiating cells in CRPC. Recently, castration-resistant cells expressing the NK3 homeobox 1 (Nkx3-1) (CARNs), the other luminal markers cytokeratin 18 (CK18) and androgen receptor (AR), and possessing SC properties, have been found in castrated mouse prostate and proposed as the cell-of-origin of CRPC. However, the human counterpart of CARNs has not been identified yet. Here, we demonstrate that in the human PC xenograft BM18, pre-existing SC-like and neuroendocrine (NE) PC cells are selected by castration and survive as totally quiescent. SC-like BM18 cells, displaying the SC markers aldehyde dehydrogenase 1A1 or NANOG, coexpress the luminal markers NKX3-1, CK18, and a low level of AR (AR(low)) but not basal or NE markers. These CR luminal SC-like cells, but not NE cells, reinitiate BM18 tumor growth after androgen replacement. The AR(low) seems to mediate directly both castration survival and tumor reinitiation. This study identifies for the first time in human PC SC-/CARN-like cells that may represent the cell-of-origin of tumor reinitiation as CRPC. This finding will be fundamental for refining the hierarchy among human PC cancer cells and may have important clinical implications.

Outcome predictors of radical prostatectomy followed by adjuvant androgen deprivation in patients with clinical high risk prostate cancer and pT3 surgical margin positive disease

Patients with high risk prostate cancer with pT3 tumor and positive surgical margins have a high risk of biochemical failure after radical prostatectomy and adjuvant androgen deprivation therapy. Predictors of cancer related death in this patient group are necessary.

[How should hormone therapy for castration-resistant prostate cancer be continued?]

After an average of 18-36 months under androgen suppression therapy by surgical castration, LHRH, and steroidal or non-steroidal antiandrogens, almost all patients with metastatic prostate cancer show PSA progression as a sign of androgen-independent but still androgen-sensitive tumor growth. Our understanding and the treatment of such castration-resistant prostate cancer has changed markedly. The introduction of new drugs like abiraterone and MDV3100 has shown that prostate cancer progression even in the"hormone-refractory" stage is driven by androgen receptor signaling. Based on this information the question of whether androgen deprivation therapy in castration-resistant prostate cancer should be continued or not is still of relevance. This review gives a critical overview of the literature and current guideline recommendations.

Immediate or deferred androgen deprivation for patients with prostate cancer not suitable for local treatment with curative intent: European Organisation for Research and Treatment of Cancer (EORTC) Trial 30891

PURPOSE: This study (EORTC 30891) attempted to demonstrate equivalent overall survival in patients with localized prostate cancer not suitable for local curative treatment treated with immediate or deferred androgen ablation. PATIENTS AND METHODS: We randomly assigned 985 patients with newly diagnosed prostate cancer T0-4 N0-2 M0 to receive androgen deprivation either immediately (n = 493) or on symptomatic disease progression or occurrence of serious complications (n = 492). RESULTS: Baseline characteristics were well balanced in the two groups. Median age was 73 years (range, 52 to 81). At a median follow-up of 7.8 years, 541 of 985 patients had died, mostly of prostate cancer (n = 193) or cardiovascular disease (n = 185). The overall survival hazard ratio was 1.25 (95% CI, 1.05 to 1.48; noninferiority P > .1) favoring immediate treatment, seemingly due to fewer deaths of nonprostatic cancer causes (P = .06). The time from randomization to progression of hormone refractory disease did not differ significantly, nor did prostate-cancer specific survival. The median time to the start of deferred treatment after study entry was 7 years. In this group 126 patients (25.6%) died without ever needing treatment (44% of the deaths in this arm). CONCLUSION: Immediate androgen deprivation resulted in a modest but statistically significant increase in overall survival but no significant difference in prostate cancer mortality or symptom-free survival. This must be weighed on an individual basis against the adverse effects of life-long androgen deprivation, which may be avoided in a substantial number of patients with a deferred treatment policy.

Androgen deprivation therapy for the treatment of prostate cancer: consider both benefits and risks

CONTEXT: Androgen deprivation therapy (ADT) is increasingly used for the treatment of prostate cancer (PCa), even in clinical settings in which there is no evidence-based proof of prolonged overall survival (OS). ADT, however, may be associated with numerous side effects, including an increased therapy-related cardiovascular mortality. OBJECTIVE: To discuss different clinical settings in which ADT is currently used and to critically weigh the benefits of ADT against its possible side effects. EVIDENCE ACQUISITION: A MEDLINE search was conducted to identify original articles and review articles addressing the efficacy and side effects of ADT for the treatment of PCa. Keywords consisted of prostate cancer, hormonal therapy, adverse effects, radical prostatectomy, and radiotherapy. The articles with the highest level of evidence for the various examined end points were identified with the consensus of all authors and were reviewed. EVIDENCE SYNTHESIS: Even short-term use of ADT may lead to numerous side effects, such as osteoporosis, obesity, sarcopenia, lipid alterations, insulin resistance, and increased risk for diabetes and cardiovascular morbidity. Despite these side effects, ADT is commonly used in various clinical settings in which a clear effect on improved OS has not been shown. CONCLUSIONS: ADT is associated with an increased risk of multiple side effects that may reduce quality of life and/or OS. Consequently, these issues should be discussed in detail with patients and their families before initiation of ADT. ADT should be used with knowledge of its potential long-term side effects and with possible lifestyle interventions, especially in settings with the highest risk-benefit ratio, to alleviate comorbidities.

Using PSA to guide timing of androgen deprivation in patients with T0-4 N0-2 M0 prostate cancer not suitable for local curative treatment (EORTC 30891)

OBJECTIVE: EORTC trial 30891 compared immediate versus deferred androgen-deprivation therapy (ADT) in T0-4 N0-2 M0 prostate cancer (PCa). Many patients randomly assigned to deferred ADT did not require ADT because they died before becoming symptomatic. The question arises whether serum prostate-specific antigen (PSA) levels may be used to decide when to initiate ADT in PCa not suitable for local curative treatment. METHODS: PSA data at baseline, PSA doubling time (PSADT) in patients receiving no ADT, and time to PSA relapse (>2 ng/ml) in patients whose PSA declined to <2 ng/ml within the first year after immediate ADT were analyzed in 939 eligible patients randomly assigned to immediate (n=468) or deferred ADT (n=471). RESULTS: In both arms, patients with a baseline PSA>50 ng/ml were at a>3.5-fold higher risk to die of PCa than patients with a baseline PSA12 mo. Time to PSA relapse after response to immediate ADT correlated significantly with baseline PSA, suggesting that baseline PSA may also reflect disease aggressiveness. CONCLUSIONS: Patients with a baseline PSA>50 ng/ml and/or a PSADT<12 mo were at increased risk to die from PCa and might have benefited from immediate ADT, whereas patients with a baseline PSA<50 ng/ml and a slow PSADT (>12 mo) were likely to die of causes unrelated to PCa, and thus could be spared the burden of immediate ADT.

Targeted radiotherapy of prostate cancer with a gastrin-releasing peptide receptor antagonist is effective as monotherapy and in combination with rapamycin

UNLABELLED The gastrin-releasing peptide receptor (GRPr) is overexpressed in prostate cancer and is an attractive target for radionuclide therapy. In addition, inhibition of the protein kinase mammalian target of rapamycin (mTOR) has been shown to sensitize various cancer cells to the effects of radiotherapy. METHODS To determine the effect of treatment with rapamycin and radiotherapy with a novel (177)Lu-labeled GRPr antagonist ((177)Lu-RM2, BAY 1017858) alone and in combination, in vitro and in vivo studies were performed using the human PC-3 prostate cancer cell line. PC-3 cell proliferation and (177)Lu-RM2 uptake after treatment with rapamycin were assessed in vitro. To determine the influence of rapamycin on (177)Lu-RM2 tumor uptake, in vivo small-animal PET studies with (68)Ga-RM2 were performed after treatment with rapamycin. To study the efficacy of (177)Lu-RM2 in vivo, mice with subcutaneous PC-3 tumors were treated with (177)Lu-RM2 alone or after pretreatment with rapamycin. RESULTS Stable expression of GRPr was maintained after rapamycin treatment with doses up to 4 mg/kg in vivo. Monotherapy with (177)Lu-RM2 at higher doses (72 and 144 MBq) was effective in inducing complete tumor remission in 60% of treated mice. Treatment with 37 MBq of (177)Lu-RM2 and rapamycin in combination led to significantly longer survival than with either agent alone. No treatment-related toxicity was observed. CONCLUSION Radiotherapy using a (177)Lu-labeled GRPr antagonist alone or in combination with rapamycin was efficacious in inhibiting in vivo tumor growth and may be a promising strategy for treatment of prostate cancer.

Significance of Increased Tissue Transglutaminase in Hormone Refractory Prostate Cancer

The progression of hormone responsive to hormone refractory prostate cancer poses a major clinical challenge in the successful treatment of prostate cancer. The hormone refractory prostate cancer cells exhibit resistance not only to castrate levels of testosterone, but also to other therapeutic modalities and hence become lethal. Currently, there is no effective treatment available for managing this cancer. These observations underscore the urgency to investigate mechanism(s) that contribute to the progression of hormone-responsive to hormone-refractory prostate cancer and to target them for improved clinical outcomes. Tissue transglutaminase (TG2) is a multifunctional pro-inflammatory protein involved in diverse physiological processes such as inflammation, tissue repair, and wound healing. Its expression is also implicated in pathological conditions such as cancer and fibrosis. Interestingly, we found that the androgen-independent prostate cancer cell lines, which lacked androgen receptor (AR) expression, contained high basal levels of tissue transglutaminase. Inversely, the cell lines that expressed androgen receptor lacked transglutaminase expression. This attracted our attention to investigate the possible role this protein may play in the progression of prostate cancer, especially in view of recent observations that its expression is linked with increased invasion, metastasis, and drug resistance in multiple cancer cell types. The results we obtained were rather surprising and revealed that stable expression of tissue transglutaminase in androgen-sensitive LNCaP prostate cancer cells rendered these cells independent of androgen for growth and survival by silencing the AR expression. The AR silencing in TG2 expressing cells (TG2-infected LNCaP and PC-3 cells) was due to TG2-induced activation of the inflammatory nuclear transcription factor-kB (NF-kB). Thus, TG2 induced NF-kB was found to directly bind to the AR promoter. Importantly, TG2 protein was specifically recruited to the AR promoter in complex with the p65 subunit of NF-kB. Moreover, TG2 expressing LNCaP and PC-3 cells exhibited epithelial-to-mesenchymal transition, as evidenced by gain of mesenchymal (such as fibronectin, vimentin, etc.) and loss of epithelial markers (such as E-cadherin, b-catenin). Taken together, these results suggested a new function for TG2 and revealed a novel mechanism that is responsible for the progression of prostate cancer to the aggressive hormone-refractory phenotype.

Genetic predisposition to prostate cancer

Prostate cancer (PC) is a significant economic and health burden in the U.S. and Europe but its causes are largely unknown. The most significant risk factors (after gender) are age and family history of the disease. A gene with high penetrance but low frequency on chromosome 1q, HPC 1, has been suggested to cause a proportion of the familial aggregation of PC but other more common genes, conferring less risk, are also thought to contribute to disease predisposition. We have pursued a strategy to study both types of genetic risk in PC. To identify high penetrance genes, affected men from thirteen families have been genotyped for genetic linkage analysis at six microsatellite markers spanning 45 cM of 1q24-25. Both LOD score and non-parametric statistics provide no significant support for HPC1 in this genomic region, although 3 of the families did combine to produce a LOD score of 0.9. These families will be included in a genome wide search for other PC predisposition genes as part of a multinational collaboration.^ For study of common genetic factors in PC development, leukocyte DNA samples from an unselected series of 55 patients and 67 controls have been examined for genetic differences in two other candidate genes, the androgen receptor gene, hAR, at Xq11-12, and the vitamin D receptor gene, hVDR, at 12q12-14. hAR was typed for two trinucleotide repeat length polymorphisms, (CAG)$\rm\sb{n}$ and (GGC)$\rm\sb{n},$ encoding polyglutamine and polyglycine tracts, respectively, which have been implicated in PC susceptibility. These data, combined with similarly processed patients and controls from the U.K. show no consistent association of allele length with PC risk. A novel finding, however, has been a significant association between the number of GGC repeats and the length of time between diagnosis and relapse in stage T1-T4 Caucasian patients irrespective of therapy and age of the patient. Of 49 patients who relapsed out of 108 entering the study, those with 16 or fewer GGC repeats had an average relapse-free-period of 101 (+/$-$7.7) months while for those with more than 16 repeats the period averaged 48 (+/$-$2.9) months, a difference of 2.1 fold or 4.4 years.^ The second gene, hVDR, was genotyped at two polymorphisms, a synonymous C/T substitution in exon 9 identified by differential TaqI enzymatic digestion and a variable length polyA tract in the 3$\sp\prime$ UTR. Although these polymorphisms are in strong linkage disequilibrium only the polyA region showed a possible association with PC risk. Men homozygous for alleles with fewer than 18 A's had an increased risk (OR = 3.0, p = 0.0578) compared to controls. This result is opposite to the findings of others and may either indicate off-setting random errors which together balance out to no significant overall effect or reflect more complex genetic and/or environmental associations.^ Overall, this research suggests that single gene familial predisposition may be less prominent in PC than in other cancers and that the characteristics of PC pathology may be useful in identifying the effects of common genetic factors. ^