The androgen receptor is a negative regulator of eIF4E phosphorylation at S209: implications for the use of mTOR inhibitors in advanced prostate cancer.

The antiandrogen bicalutamide is widely used in the treatment of advanced prostate cancer (PCa) in many countries, but its effect on castration-resistant PCa (CRPC) is limited. We previously showed that resistance to bicalutamide results from activation of mechanistic target of rapamycin (mTOR). Interestingly, clinical trials testing combinations of the mTOR inhibitor RAD001 with bicalutamide were effective in bicalutamide-naïve CRPC patients, but not in bicalutamide-pretreated ones. Here we investigate causes for their difference in response. Evaluation of CRPC cell lines identified resistant vs sensitive in vitro models, and revealed that increased eIF4E(S209) phosphorylation is associated with resistance to the combination. We confirmed using a human-derived tumor xenograft mouse model that bicalutamide pre-treatment is associated with an increase in eIF4E(S209) phosphorylation. Thus, AR suppressed eukaryotic initiation factor 4E (eIF4E) phosphorylation, while the use of antiandrogens relieved this suppression, thereby triggering its increase. Additional investigation in human prostatectomy samples showed that increased eIF4E phosphorylation strongly correlated with the cell proliferation marker Ki67. Small interfering RNA-mediated knockdown (k/d) of eIF4E-sensitized CRPC cells to RAD001+bicalutamide, whereas eIF4E overexpression induced resistance. Inhibition of eIF4E phosphorylation by treatment with CGP57380 (an inhibitor of mitogen-activated protein kinase-interacting serine-threonine kinases MAP kinase-interacting kinase 1 (Mnk1/2), the eIF4E upstream kinase) or inhibitors of extracellular signal-regulated kinase 1/2 (ERK1/2), the upstream kinase-regulating Mnk1/2, also sensitized CRPC cells to RAD001+bicalutamide. Examination of downstream targets of eIF4E-mediated translation, including survivin, demonstrated that eIF4E(S209) phosphorylation increased cap-independent translation, whereas its inhibition restored cap-dependent translation, which could be inhibited by mTOR inhibitors. Thus, our results demonstrate that while combinations of AR and mTOR inhibitors were effective in suppressing tumor growth by inhibiting both AR-induced transcription and mTOR-induced cap-dependent translation, pre-treatment with AR antagonists including bicalutamide increased eIF4E phosphorylation that induced resistance to combinations of AR and mTOR inhibitors by inducing cap-independent translation. We conclude that this resistance can be overcome by inhibiting eIF4E phosphorylation with Mnk1/2 or ERK1/2 inhibitors.

Targeting autophagy overcomes Enzalutamide resistance in castration-resistant prostate cancer cells and improves therapeutic response in a xenograft model.

Macro-autophagy is associated with drug resistance in various cancers and can function as an adaptive response to maintain cell survival under metabolic stresses, including androgen deprivation. Androgen deprivation or treatment with androgen receptor (AR) signaling inhibitor (ARSI), Enzalutamide (MDV-3100, ENZA) or bicalutamide induced autophagy in androgen-dependent and in castration-resistant CaP (castration-resistant prostate cancer (CRPC)) cell lines. The autophagic cascade triggered by AR blockage, correlated with the increased light chain 3-II/I ratio and ATG-5 expression. Autophagy was observed in a subpopulation of C4-2B cells that developed insensitivity to ENZA after sustained exposure in culture. Using flow cytometry and clonogenic assays, we showed that inhibiting autophagy with clomipramine (CMI), chloroquine or metformin increased apoptosis and significantly impaired cell viability. This autophagic process was mediated by AMP-dependent protein kinase (AMPK) activation and the suppression of mammalian target of rapamycin (mTOR) through Raptor phosphorylation (Serine 792). Furthermore, small interfering RNA targeting AMPK significantly inhibited autophagy and promoted cell death in CaP cells acutely or chronically exposed to ENZA or androgen deprivation, suggesting that autophagy is an important survival mechanism in CRPC. Lastly, in vivo studies with mice orthotopically implanted with ENZA-resistant cells demonstrated that the combination of ENZA and autophagy modulators, CMI or metformin significantly reduced tumor growth when compared with control groups (P<0.005). In conclusion, autophagy is as an important mechanism of resistance to ARSI in CRPC. Antiandrogen-induced autophagy is mediated through the activation of AMPK pathway and the suppression of mTOR pathway. Blocking autophagy pharmacologically or genetically significantly impairs prostate cancer cell survival in vitro and in vivo, implying the therapeutics potential of autophagy inhibitors in the antiandrogen-resistance setting.

miR-30 as a tumor suppressor connects EGF/Src signal to ERG and EMT.

Src tyrosine kinase (Src) is implicated in the development of bone metastasis and castration resistance of prostate cancer. Src inhibitors are currently being tested in clinical trials for such diseases. Understanding the molecular and cellular actions of Src inhibitors holds the key to future improvement of this line of therapy. Here we describe the microRNA expression profiles modulated by two Src inhibitors and demonstrate that the miR-30 family members are the most prominently induced species. Consistent with its tumor suppressor role, miR-30 is downmodulated by oncogenic signals such as epidermal growth factor (EGF) and hepatocyte growth factor, and is generally underexpressed in prostate cancer specimens. A number of epithelial-to-mesenchymal transition (EMT)-associated genes are predicted targets of miR-30. Among these genes the Ets-related gene (ERG) is the most frequently overexpressed oncogene in prostate cancer activated by genomic fusion events between promoter upstream sequences of the TMPRSS2 and coding sequences of ERG. We showed by ERG 3' untranslated region reporter and mutagenesis assays that ERG is a direct target of miR-30. Overexpression of miR-30 in prostate cancer cells suppresses EMT phenotypes and inhibits cell migration and invasion. It also inhibits the in vitro and in vivo growth of VCaP cells, which depends on TMPRSS2-ERG for proliferation. TMPRSS2-ERG is generally regulated by androgen at the transcriptional level. Our finding reveals a new post-transcriptional mechanism of TMPRSS2-ERG regulation by Src and growth signals via miR-30 providing a rationale for targeting ERG-positive castration-resistant tumors with Src inhibitors.

Tumor suppressive miR-124 targets androgen receptor and inhibits proliferation of prostate cancer cells.

Although prostate cancer (CaP) is the most frequently diagnosed malignant tumor in American men, the mechanisms underlying the development and progression of CaP remain largely unknown. Recent studies have shown that downregulation of the microRNA miR-124 occurs in several types of human cancer, suggesting a tumor suppressive function of miR-124. Until now, however, it has been unclear whether miR-124 is associated with CaP. In the present study, we completed a series of experiments to understand the functional role of miR-124 in CaP. We detected the expression level of miR-124 in clinical CaP tissues, evaluated the influence of miR-124 on the growth of CaP cells and investigated the mechanism underlying the dysregulation of miR-124. We found that (i) miR-124 directly targets the androgen receptor (AR) and subsequently induces an upregulation of p53; (ii) miR-124 is significantly downregulated in malignant prostatic cells compared to benign cells, and DNA methylation causes the reduced expression of miR-124; and (iii) miR-124 can inhibit the growth of CaP cells in vitro and in vivo. Data from this study revealed that loss of miR-124 expression is a common event in CaP, which may contribute to the pathogenesis of CaP. Our studies also suggest that miR-124 is a potential tumor suppressive gene in CaP, and restoration of miR-124 expression may represent a novel strategy for CaP therapy.

Nucleic Acid, Antibody, and Virus Culture Methods to Detect Xenotropic MLV-Related Virus in Human Blood Samples.

The MLV-related retrovirus, XMRV, was recently identified and reported to be associated with both prostate cancer and chronic fatigue syndrome. At the National Cancer Institute-Frederick, MD (NCI-Frederick), we developed highly sensitive methods to detect XMRV nucleic acids, antibodies, and replication competent virus. Analysis of XMRV-spiked samples and/or specimens from two pigtail macaques experimentally inoculated with 22Rv1 cell-derived XMRV confirmed the ability of the assays used to detect XMRV RNA and DNA, and culture isolatable virus when present, along with XMRV reactive antibody responses. Using these assays, we did not detect evidence of XMRV in blood samples (N = 134) or prostate specimens (N = 19) from two independent cohorts of patients with prostate cancer. Previous studies detected XMRV in prostate tissues. In the present study, we primarily investigated the levels of XMRV in blood plasma samples collected from patients with prostate cancer. These results demonstrate that while XMRV-related assays developed at the NCI-Frederick can readily measure XMRV nucleic acids, antibodies, and replication competent virus, no evidence of XMRV was found in the blood of patients with prostate cancer.

The effect of sirolimus on prostate-specific antigen (PSA) levels in male renal transplant recipients without prostate cancer.

In kidney recipients, the immunosuppressant sirolimus has been associated with a decreased incidence of de novo posttransplant malignancies (including prostate cancer). But the effect of sirolimus on the prostate-specific antigen (PSA) blood level, an important prostate cancer screening tool, remains unknown. We studied male kidney recipients >50 years old (transplanted from January 1994 to December 2006) without clinical evidence for prostate cancer. Pre- and posttransplant PSA levels were analyzed for 97 recipients (n = 19 on sirolimus, n = 78 on tacrolimus [control group]). Pretransplant PSA was similar for sirolimus versus tacrolimus recipients (mean, 1.8 versus 1.7 ng/mL, p = 0.89), but posttransplant PSA was significantly lower for recipients on sirolimus (mean, 0.9 versus 1.9 ng/mL, respectively, p < 0.001). The mean difference between pretransplant and posttransplant PSA was -0.9 ng/mL (50.0%, p = 0.006) for the sirolimus group versus +0.2 ng/mL (+11.8%, p = 0.24) for the tacrolimus group. By multivariate analysis, only pretransplant PSA and immunosuppression with sirolimus independently impacted posttransplant PSA. Our data strongly suggest that sirolimus is associated with a significant PSA decrease in kidney recipients. Future studies must investigate the clinical implications of our findings for the use of PSA for prostate cancer screening in male kidney recipients on sirolimus.

Regulation of androgen receptor transcriptional activity by rapamycin in prostate cancer cell proliferation and survival.

The mTOR (mammalian target of rapamycin) inhibitor rapamycin caused growth arrest in both androgen-dependent and androgen-independent prostate cancer cells; however, long-term treatment induced resistance to the drug. The aim of this study was to investigate methods that can overcome this resistance. Here, we show that rapamycin treatment stimulated androgen receptor (AR) transcriptional activity, whereas suppression of AR activity with the antiandrogen bicalutamide sensitized androgen-dependent, as well as AR-sensitive androgen-independent prostate cancer cells, to growth inhibition by rapamycin. Further, the combination of rapamycin and bicalutamide, but not the individual drugs, induced significant levels of apoptosis in prostate cancer cells. The net effect of rapamycin is determined by its individual effects on the mTOR complexes mTORC1 (mTOR/raptor/GbetaL) and mTORC2 (mTOR/rictor/sin1/GbetaL). Inhibition of both mTORC1 and mTORC2 by rapamycin-induced apoptosis, whereas rapamycin-stimulation of AR transcriptional activity resulted from the inhibition of mTORC1, but not mTORC2. The effect of rapamycin on AR transcriptional activity was mediated by the phosphorylation of the serine/threonine kinase Akt, which also partially mediated apoptosis induced by rapamycin and bicalutamide. These results indicate the presence of two parallel cell-survival pathways in prostate cancer cells: a strong Akt-independent, but rapamycin-sensitive pathway downstream of mTORC1, and an AR-dependent pathway downstream of mTORC2 and Akt, that is stimulated by mTORC1 inhibition. Thus, the combination of rapamycin and bicalutamide induce apoptosis in prostate cancer cells by simultaneously inhibiting both pathways and hence would be of therapeutic value in prostate cancer treatment.

Inappropriate activation of androgen receptor by relaxin via beta-catenin pathway.

We have previously demonstrated that human H2-relaxin can mediate androgen-independent growth of LNCaP through a mechanism that involves the activation of the androgen receptor (AR) signaling pathway. The goal of the current study is to elucidate the mechanism(s) by which H2-relaxin causes activation of the AR pathway. Our data indicate that there is cross-talk between AR and components of the Wnt signaling pathway. Addition of H2-relaxin to LNCaP cells resulted in increased phosphorylation of protein kinase B (Akt) and inhibitory phosphorylation of glycogen synthase kinase-3beta (GSK-3beta) with subsequent cytoplasmic accumulation of beta-catenin. Immunoprecipitation and immunocytochemical studies demonstrated that the stabilized beta-catenin formed a complex with AR, which was then translocated into the nucleus. Chromatin immunoprecipitation analysis determined that the AR/beta-catenin complex binds to the proximal region of the prostate-specific antigen promoter. Inhibition of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, using LY294002, prevented both H2-relaxin-mediated phosphorylation of Akt and GSK-3beta and translocation of beta-catenin/AR into the nucleus. Knockdown of beta-catenin levels using a beta-catenin-specific small interfering RNA inhibited H2-relaxin-induced AR activity. The combined data demonstrate that PI3K/Akt and components of the Wnt pathway can facilitate H2-relaxin-mediated activation of the AR pathway.

Inhibition of Akt pathways in the treatment of prostate cancer.

Akt is a serine/threonine kinase mediating multiple intracellular pathways involved in prostate cancer (CaP) biology. Increased understanding of the molecular mechanisms of Akt activation and signaling have led to the development of an increasing number of Akt inhibitors. These biologic agents demonstrate activity against a wide range of cancers in preclinical studies. Clinical studies of Akt inhibition in CaP are in progress, including agents such as celecoxib, perifosine and genistein. How best to integrate Akt inhibitors with standard CaP therapy or select patients most likely to benefit is the subject of ongoing research.

A 90 kDa fragment of filamin A promotes Casodex-induced growth inhibition in Casodex-resistant androgen receptor positive C4-2 prostate cancer cells.

Prostate tumors are initially dependent on androgens for growth, but the majority of patients treated with anti-androgen therapy progress to androgen-independence characterized by resistance to such treatment. This study investigates a novel role for filamin A (FlnA), a 280 kDa cytoskeletal protein (consisting of an actin-binding domain (ABD) followed by 24 sequential repeats), in androgen-independent (AI) growth. Full-length FlnA is cleaved to 170 kDa (ABD+FlnA1-15) and 110 kDa fragments (FlnA16-24); the latter is further cleaved to a 90 kDa fragment (repeats 16-23) capable of nuclear translocation and androgen receptor (AR) binding. Here, we demonstrate that in androgen-dependent LNCaP prostate cancer cells, the cleaved 90 kDa fragment is localized to the nucleus, whereas in its AI subline C4-2, FlnA failed to cleave and remained cytoplasmic. Transfection of FlnA16-24 cDNA in C4-2 cells restored expression and nuclear localization of 90 kDa FlnA. Unlike LNCaP, C4-2 cells proliferate in androgen-reduced medium and in the presence of the AR-antagonist Casodex. They also exhibit increased Akt phosphorylation compared to LNCaP, which may contribute to their AI phenotype. Nuclear expression of 90 kDa FlnA in C4-2 cells decreased Akt phosphorylation, prevented proliferation in androgen-reduced medium and restored Casodex sensitivity. This effect was inhibited by constitutive activation of Akt indicating that FlnA restored Casodex sensitivity in C4-2 cells by decreasing Akt phosphorylation. In addition, FlnA-specific siRNA which depleted FlnA levels, but not control siRNA, induced resistance to Casodex in LNCaP cells. Our results demonstrate that expression of nuclear FlnA is necessary for androgen dependence in these cells.

Abnormalities of apoptotic and cell cycle regulatory proteins in distinct histopathologic components of benign prostatic hyperplasia.

INTRODUCTION: Benign prostatic hyperplasia (BPH) is a slowly progressive abnormal glandular enlargement with heterogeneous morphology. Disruption of apoptotic pathways has been suggested as an important regulatory mechanism in this common and significantly morbid disease. METHODS: Prostatic tissue from 20 patients with BPH and no prior or subsequent prostatic carcinoma was obtained by transurethral prostatectomy (TURP) at the University of California Davis. Apoptotic regulatory proteins: BCL2, BAX and p27 were analyzed by immunohistochemistry and evaluated for expression in four distinct histologic patterns: hyperplastic epithelium, nodules, dilated glands and atrophic/inflammatory glands. RESULTS: Particularly striking was the decreased expression of BAX and an abnormal BCL2 : BAX ratio within all nodules relative to expression in other epithelial patterns. p27 expression was decreased in 35% of the hyperplastic epithelial areas and 10% of the nodules. DISCUSSION: Overall, abnormal expression of BCL2, BAX and/or p27 was identified in the hyperplastic epithelium of 19 (90%) of specimens and all 12 (100%) of the hyperplastic nodules. The high frequency of abnormalities in apoptosis regulatory genes, suggests that alteration of apoptotic pathways is important for the development of this condition.

Differences in gene expression in muscle-invasive bladder cancer: a comparison of Italian and American patients.

OBJECTIVE: To seek differences in gene expression in the primary muscle-invasive bladder cancers of two cohorts of patients having different survival rates. An Italian group treated by transurethral resection of the bladder tumor (TURBT) and neo-adjuvant chemotherapy using methotrexate, vinblastine, adriamycin and cisplatin (M-VAC) followed by TURBT, partial cystectomy or radical cystectomy (75% 3-year survival) was compared to an American cohort treated by radical cystectomy (51% 3-year survival). METHODS: Immunohistochemistry was used to examine the protein expression levels of three genes that act at the G1/S cell cycle checkpoint, p53, p21/waf-1/cip1 (a downstream effector gene in the p53 pathway) and Rb, plus a major inhibitor of apoptosis, Bcl-2. RESULTS: For the bladder cancers of the Italian patient cohort, there was a significantly higher rate of p53 immunopositivity (93 vs. 63%, p = 0.002) and a significantly lower rate of Rb loss (25 vs. 54%, p = 0.009). In bivariate analysis, 72% of Italian tumors were immunopositive for both p53 and p21 (p53+/p21+) vs. 49% for the American tumors. The subset of Italian patients with p53+/p21+ tumors were more frequently disease-free (stage pT0) following chemotherapy and were less likely to fail therapy than those with p53+/p21- tumors (p = 0.0357). Loss of Rb staining was associated with a decreased 5-year survival in the Italian, but not in the American patients. CONCLUSIONS: (1) Significant differences in the expression of the p53, p21 and Rb genes were found between the 2 groups of patients. (2) Italian patients with p53+/p21+ tumors had significantly lower recurrence rates after TURBT and chemotherapy than those having p53+/p21- tumors. (3) Absence of p21 immunopositivity in the Italian tumors may identify alterations in the p53 pathway that predict poor outcome.

BCL2 antisense transcripts decrease intracellular Bcl2 expression and sensitize LNCaP prostate cancer cells to apoptosis-inducing agents.

Prostate cancer (CaP) is the most commonly diagnosed cancer of aging men and the second leading cause of male cancer death in the United States. At present, no effective therapy is available for treating hormone independent CaP. Since Bcl2 is believed to play a role in protecting CaP cells from apoptosis, we investigated the effects of down-regulating Bcl2 expression on CaP cells. Genetically engineered LNCaP sublines were established by stably transfecting LNCaP cells with BCL2 antisense (BCL2-AS) transcript-expressing plasmids. Western blotting analysis showed that intracellular Bcl2 protein was decreased by 50-60% in BCL2-AS-transfected LNCaP cells. Expression of the antisense transcripts resulted in 50% growth inhibition of LNCaP cells in response to androgen withdrawal and markedly sensitized these cells to Adriamycin-induced apoptosis. These results suggest that down-regulation of Bcl2 protein using BCL2-AS transcripts could be exploited for improved treatment of advanced CaP.

Acute toxicity of three-dimensional conformal radiotherapy in prostate cancer patients eligible for implant monotherapy.

PURPOSE: To assess the acute toxicity of three-dimensional conformal radiotherapy (3D-CRT) in prostate cancer patients eligible for implant monotherapy. METHODS AND MATERIALS: Between December 1991 and June 1998, 198 prostate cancer patients were treated with 3D-CRT at the University of California Davis Medical Center. Fifty-two of these patients had a prostate-specific antigen (PSA) level /= Grade 3, e.g., hourly nocturia, gross hematuria, diarrhea requiring parenteral support, narcotics for pain control, or catheterization for acute urinary retention, was observed. CONCLUSION: Although relatively high doses of radiation are delivered to prostate cancers with 3D-CRT compared with conventional radiotherapy, 3D-CRT is surprisingly well-tolerated. No patients in the cohort eligible for implant monotherapy experienced acute toxicity >/= Grade 3.

The prognostic significance of S-phase analysis in stage Ta/T1 bladder cancer. A Southwest Oncology Group Study.

OBJECTIVES: An intergroup study (SWOG 8795) comparing two forms of adjunctive therapy (immuno and chemo), bacillus Calmette-Guerin (BCG) and mitomycin C (MMC), furnished preregistration index tumors for 244 patients with superficial, papillary stage Ta/T1 TCC. These were examined by flow cytometry to learn whether DNA ploidy or proliferation (low vs high S-phase fraction (SPF) helped to predict disease recurrence or progression. METHODS: Cell cycle analysis using commercially available (Multicycle) programs was performed on 249 Ta/T1 bladder cancers. Tumor grade, available for 223 cases, was assigned by a single study pathologist. The SWOG statistical office reviewed follow-up information and other data and performed statistical analysis. RESULTS: Disease recurrence occurred in half the cases studied. The most parsimonious model predictive of recurrence included only treatment arm and tumor grade, with the MMC arm and tumor grade greater than I indicating worse prognosis (p = 0. 014). Neither ploidy nor SPF predicted recurrence-free survival or contributed prognostic information that was additive to tumor grade. Within 5 years of follow-up, disease progression or death from bladder cancer occurred for 29/223 (13%) of patients. The most parsimonious model for progression-free survival included only grade greater than I (p<0.001) and high SPF (p = 0.029) (relative risk: tumor grade, 4.3, high SPF, 1.9). CONCLUSIONS: Knowledge of tumor proliferation (low versus high SPF) contributes prognostic information about tumor progression that is additive to tumor grade.

Phase I/II study of paclitaxel, carboplatin, and methotrexate in advanced transitional cell carcinoma: a well-tolerated regimen with activity independent of p53 mutation.

OBJECTIVES: To evaluate the feasibility and activity of paclitaxel, carboplatin, and methotrexate in advanced transitional cell carcinoma (TCC) of the urothelium and to relate the activity of this combination to the mutational status of p53. METHODS: In the Phase I portion, paclitaxel 200 mg/m(2) (3-hour infusion), carboplatin dosed to an area under the curve (AUC) of 6 mg/mL. min, and methotrexate 10 mg/m(2), increasing in 10-mg/m(2) increments, were administered on day 1 and every 21 days thereafter with granulocyte colony-stimulating factor (G-CSF) and leucovorin support. Subsequently, a Phase II study was initiated in which the carboplatin dose was lowered to an AUC of 5 to allow treatment without G-CSF. p53 expression was evaluated using immunohistochemistry. RESULTS: Thirty-three patients were accrued. Median age was 66 years. No dose-limiting toxicities were seen in the Phase I portion despite escalation of the methotrexate to 60 mg/m(2). Principal toxicities were myelosuppression and neuropathy. The overall response rate (Phase I and II) was 56% (95% confidence interval 38% to 74%). Median survival was 15.5 months; 88% of patients overexpressed p53 at the primary site. CONCLUSIONS: Paclitaxel, carboplatin, and methotrexate were well tolerated and active in advanced TCC. The high response rate to this regimen despite frequent p53 mutation is consistent with the p53-independent mechanism of paclitaxel. Whether this regimen is superior to methotrexate/vinblastine/doxorubicin/cisplatin, other paclitaxel-based regimens, or to paclitaxel alone will require comparative trials.

Use of a yeast assay to detect functional alterations in p53 in prostate cancer: review and future directions.

BACKGROUND: While many studies have suggested that p53 mutations are common in human cancers, the functional activity of these mutant alleles has not yet been fully addressed. We believe that information about the functional status of individual p53 mutants will prove to be important for a better understanding of the role of p53 in tumor development and progression. Ultimately, this information could also influence treatment decisions for individual cancer patients. METHODS: A recently developed yeast functional assay can be used to assess the transactivational activity of p53 mutants. Furthermore, this assay is more sensitive than single strand conformational polymorphism (SSCP) for detection of p53 mutations. In this review, we summarize the mechanism of this new technique and describe its applications in cancer research, with an emphasis on prostate cancer. RESULTS: The use of the yeast functional assay provides a simple, sensitive, and reproducible method for detecting p53 mutations and for determining the transactivational activity and dominant-negative role of individual p53 mutants. CONCLUSIONS: This method may be adapted to analyze other transcriptional factors, including the human androgen receptor.

Future prospects in prostate cancer.

BACKGROUND: Prostate cancer has displayed an increase in incidence unparalleled by any other tumor in the last two decades, with a steady, more gradual increase in mortality rate. Current curative strategies are focused on the detection and treatment of early-stage (T1-2 N0 M0), clinically significant tumors. METHODS: To this aim, refinement of surgical approaches, with appropriate adjuvant therapies, will ensure more complete cancer control, while minimizing associated morbidity. New delivery systems for radiotherapy, as well as other energy sources, are evolving, while a number of promising pharmacological agents, including angiogenesis inhibitors and drugs which alter signal transduction pathways, are currently under investigation. Early detection is also being facilitated by a more widespread implementation of screening programs. Advances in tumor markers, and imaging and biopsy techniques, will allow more accurate preoperative staging. These, coupled with improvements in prognostic markers, aid the physician and patient alike in deciding on the suitability of treatment options with better estimation of outcome. Perhaps the most exciting developments in prostate cancer will come from knowledge of the molecular mechanisms underlying carcinogenesis. The potential for the development of diagnostic and therapeutic tools is immense. The efficacy of treatment can be studied at a molecular level, and strategies for preventing or slowing the development of malignancy can be formulated. RESULTS AND CONCLUSIONS Application of this knowledge in the form of gene and cellular therapy and in the development of novel systemic agents is beginning to enter the realm of clinical practice, and it may be in this field that means for cure and prevention of prostate cancer will eventually be found.