Castration-resistant prostate cancer: targeted therapies and individualized treatment

Development of castration resistance in prostate cancer patients treated with luteinizing hormone-releasing hormone analogues (LHRHa): results of the ANARESISTANCE study

Purpose

Evaluate the percentage of patients with prostate cancer treated with luteinizing hormone-releasing hormone analogues (LHRHa) that develop castration resistance after a follow-up period of 3 years. The secondary objective is to evaluate the variables potentially related to the progression to castration resistant prostate cancer (CRPC).

Methods

A post-authorization, nation-wide, multicenter, prospective, observational, and longitudinal study that included 416 patients treated with LHRHa between 2012 and 2017 is presented. Patients were followed for 3 years or until development of CRPC, thus completing a per-protocol population of 350 patients. A Cox regression analysis was carried out to evaluate factors involved in progression to CRPC.

Results

After 3 years of treatment with LHRHa 18.2% of patients developed CRPC. In contrast, in the subgroup analysis, 39.6% of the metastatic patients developed CRPC, compared with 8.8% of the non-metastatic patients. The patients with the highest risk of developing CRPC were those with a nadir prostate-specific antigen (PSA) > 2 ng/ml (HR 21.6; 95% CI 11.7–39.8; p < 0.001) and those receiving concomitant medication, most commonly bicalutamide (HR 1.8; 95% CI 1–3.1, p = 0.0431).

Conclusions

The proportion of metastatic patients developing CRPC after 3 years of treatment with LHRHa is consistent with what has been previously described in the literature. In addition, this study provides new findings on CRPC in non-metastatic patients. Concomitant medication and nadir PSA are statistically significant predictive factors for the time to diagnosis of CRPC, the nadir PSA being the strongest predictor.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00345-022-04108-x.

Current Treatment Modalities Targeting Tumor Microenvironment in Castration-Resistant Prostate Cancer

Prostate cancer (PCa) is responsible for significant cancer-related morbidity and mortality following local treatment failure in men. The initial stages of PCa are typically managed with a combination of surgical resection and/or androgen deprivation therapy (ADT). Unfortunately, a significant proportion of PCa continues to progress despite being at castrate levels of testosterone (<50 ng/dl), at which point it is coined castration-resistant prostate cancer (CRPC). In recent years, many novel therapeutics and drug combinations have been created for CRPC patients. These include immune checkpoint inhibitors, chemokine receptor antagonists, steroidogenic enzyme inhibition, and novel tyrosine kinase inhibitors as well as combinations of drugs. The selection of the most appropriate therapy depends on several factors like stage of the disease, age of the patient, metastasis, functional status, and response towards previous therapies. Here, we review the current state of the literature regarding treatment modalities, focusing on the treatment recommendations per the American Urological Association (AUA), recent clinical trials, and their limitations. An accurate and reliable overview of the strengths and limitations of PCa therapeutics could also allow personalized therapeutic interventions against PCa.

Molecular Phenotyping of AR Signaling for Predicting Targeted Therapy in Castration Resistant Prostate Cancer

Castration-resistant prostate cancer (CRPC) is defined by resistance of the tumor to androgen deprivation therapy (ADT). Several molecular changes, particularly in the AR signaling cascade, have been described that may explain ADT resistance. The variety of changes may also explain why the response to novel therapies varies between patients. Testing the specific molecular changes may be a major step towards personalized treatment of CRPC patients. The aim of our study was to evaluate the molecular changes in the AR signaling cascade in CRPC patients. We have developed and validated several methods which are easy to use, and require little tissue material, for exploring AR signaling pathway changes simultaneously. We found that the AR signaling pathway is still active in the majority of our CRPC patients, due to molecular changes in AR signaling components. There was heterogeneity in the molecular changes observed, but we could classify the patients into 4 major subgroups which are: AR mutation, AR amplification, active intratumoral steroidogenesis, and combination of AR amplification and active intratumoral steroidogenesis. We suggest characterizing the AR signaling pathway in CRPC patients before beginning any new treatment, and a recent fresh tissue sample from the prostate or a metastatic site should be obtained for the purpose of this characterization.

Clinical implication of prognostic and predictive biomarkers for castration-resistant prostate cancer: a systematic review

Background

Diagnosis of metastatic castrate resistant prostate cancer (mCRPC) with current biomarkers is difficult and often results in unnecessary invasive procedures as well as over-diagnosis and over-treatment. There are a number of prognostic biomarkers for CRPC, but there are no validated predictive biomarkers to guide in clinical decision-making. Specific biomarkers are needed that enable to understand the natural history and complex biology of this heterogeneous malignancy, identify early response to treatment outcomes and to identify the population of men most likely to benefit from the treatment. In this systematic review, we discuss the existing literature for the role of biomarkers in CRPC and how they aid in the prognosis, treatment selection and survival outcomes.

Methods

We performed a literature search on PubMed and EMBASE databases from January 2015 through February 2020 in accordance to Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. Articles were assessed to identify relevant observational studies and randomized controlled trials regarding biomarkers which aid in identifying progression to mCRPC as well as predictive biomarkers which help in treatment selection.

Results

We identified 3640 number of hits of which 58 articles were found to be relevant. Here we addressed biomarkers in the context of prognosis, prediction and patient selection of therapy. These biomarkers were found to be effective as prognostic or predictive factors under variety of conditions. The higher levels for all these biomarkers were associated with shorter median OS and sometimes PFS. Lower amounts of biomarkers in serum or urine were associated with prolonged survival outcomes, longer time to CRPC development or CRPC progression and longer median follow-up irrespective of any therapy.

Conclusion

We observed that the biomarkers included in our study predicted clinically relevant survival outcomes and treatment exposure. Though the current biomarkers are prognostic when measured prior to initiating treatment, not all are validated as predictive markers in post treatment setting. A greater understanding of biomarkers in CRPC is need of the hour for development of more personalized approach to maximize benefit and minimize harm in men with CRPC.

Design, Synthesis, and Evaluation of Monoamine Oxidase A Inhibitors⁻Indocyanine Dyes Conjugates as Targeted Antitumor Agents

Monoamine oxidase A (MAOA) is an important mitochondria-bound enzyme that catalyzes the oxidative deamination of monoamine neurotransmitters. Accumulating evidence suggests a significant association of increased MAOA expression and advanced high-grade prostate cancer (PCa) progression and metastasis. Herein, a series of novel conjugates combining the MAOA inhibitor isoniazid (INH) and tumor-targeting near-infrared (NIR) heptamethine cyanine dyes were designed and synthesized. The synthesized compounds G1–G13 were evaluated in vitro for their cytotoxicity against PC-3 cells using the MTT assay, and molecular docking studies were performed. Results showed that most tested compounds exhibited improved antitumor efficacy compared with INH. Moreover, conjugates G10 and G11 showed potent anticancer activity with IC₅₀ values (0.85 and 0.4 μM respectively) comparable to that of doxorubicin (DOX). This may be attributable to the preferential accumulation of these conjugates in tumor cells. G10, G11, and G12 also demonstrated moderate MAOA inhibitory activities. This result and the results of molecular docking studies were consistent with their cytotoxicity activities. Taken together, these data suggest that a combination of the MAOA inhibitor INH with tumor-targeting heptamethine cyanine dyes may prove to be a highly promising tool for the treatment of advanced prostate cancer.

Combination therapy of hTERTR and FAM96A for hepatocellular carcinoma through enhancing apoptosis sensitivity

Avoidance of apoptosis induced by anticancer drugs is an essential factor of carcinogenesis and a hallmark of resistance to cancer therapy. Human telomerase reverse transcriptase receptor (hTERTR) is a potential anti-cancer agent for inhibiting tumor growth. Family with sequence similarity 96 member A (FAM96A) is a ubiquitous, conserved protein and possesses apoptosome-activating and pro-apoptotic tumor suppressor potential in hepatocellular carcinoma (HCC). In the present study, hTERTR and FAM96A were identified as efficient anti-cancer agents for activating apoptosomes and reducing tumor growth. The potential tumor suppressor function of combination treatment with hTERTR and FAM96A in HCC was also investigated. hTERTR and FAM96A proteins were expressed by genetic engineering and their anti-cancer function was explored in vitro and in vivo. Effects of hTERTR and FAM96A on improvement of apoptotic sensitivity and inhibition of migration and invasion were examined in cancer cells and in a mouse model. The present results demonstrated that the therapeutic effects of hTERTR and FAM96A were effective for inhibiting tumor growth and inducing apoptosis of HCC cells in H22-bearing nude mice compared with single agent treatment. hTERTR and FAM96A were found to bind with apoptotic protease activating factor 1 and human telomerase reverse transcriptase, which enhanced the apoptosis of tumor cells and apoptosis sensitivity. In addition, hTERTR and FAM96A therapy enhanced cytotoxic effects by cytotoxic T lymphocyte responses, interferon-γ release, T lymphocytes infiltration and apoptosis on tumor cells. Furthermore, hTERTR and FAM96A protein inhibited tumor growth in HCC mice. In conclusion, the present findings suggested that combination therapy with hTERTR and FAM96A may serve as novel tumor suppressor agents.

mTOR Inhibitors in Castration-Resistant Prostate Cancer: A Systematic Review

BACKGROUND

The progression of prostate cancer to castration-resistant prostate cancer (CRPC) is often a result of somatic alterations in the PI3K/Akt/mTOR (mammalian target of rapamycin) pathway, suggesting that therapies targeting this pathway might lead to improved survival and efficacy. Here, we systematically evaluate the results of clinical trials investigating mTOR inhibition in CRPC and utilize preclinical data to predict clinical outcomes.

METHODS

Trials included in the study were identified through PubMed and via review of conference abstracts cited by relevant review articles. The eligibility of trials was independent of sample size, clinical setting, or date.

RESULTS

A total of 14 studies were eligible for qualitative analysis. The clinical setting was variable among studies, and all utilized an allosteric mTOR inhibitor as either a monotherapy or in combination. Molecular criteria were evaluated in three trials. Among most studies, the prostate-specific antigen level declined during treatment, but often increased shortly thereafter. Partial responses to treatment were minimal, and no complete responses were reported. Two studies exploring therapy with an mTOR inhibitor in combination with bicalutamide resulted in minimal efficacy. Overall, allosteric mTOR inhibition was deemed to be inadequate for the treatment of CRPC.

CONCLUSION

Preclinical data suggest that a reciprocal feedback mechanism between PI3K and androgen receptor signaling is a potential mechanism behind the clinical inefficacy of mTOR inhibitors in CRPC, indicating combinatorial targeting of PI3K, mTORC1/2, and the androgen receptor might be more effective. Comprehensive analysis of preclinical data to assess clinical trial targets and efficacy may reduce the number of unproductive trials and identify potentially beneficial combinatorial therapies for resistant disease.

Preclinical trial of the multi-targeted lenvatinib in combination with cellular immunotherapy for treatment of renal cell carcinoma

Lenvatinib is an oral, multi-targeted tyrosine kinase inhibitor of vascular endothelial growth factor receptors 1-3, fibroblast growth factor receptors 1-4, platelet-derived growth factor receptor β, RET and KIT. Cellular immunotherapy has the potential to be a highly targeted treatment, with low toxicity to normal tissues and a high capacity to eradicate tumor tissue. The present study assessed the safety, maximum tolerated dose (MTD) and preliminary antitumor activity of lenvatinib and cellular immunotherapy in a murine model of renal cell carcinoma (RCC). The present study used a therapeutic dose of 0.12 mg lenvatinib and/or 10⁴ rat uterine cancer adenocarcinoma (RuCa)-sensitized lymphocytes administered once daily continuously in 7-day cycles. Tumor regression was observed in mice with RCC following treatment with lenvatinib and 10⁴ RuCa-sensitized lymphocytes. MTD was established as once daily administration of 0.18 mg lenvatinib and 10⁶ RuCa-sensitized lymphocytes. The most common treatment-related adverse effects observed were fatigue (40%), mucosal inflammation (30%), proteinuria, diarrhea, vomiting, hypertension and nausea (all 40%). Combination therapy using lenvatinib and cellular immunotherapy enhanced the antitumor effect induced by single treatments and prolonged the survival of mice with RCC compared with either of the single treatments. Treatment with lenvatinib (0.12 mg) combined with 10⁴ RuCa-sensitized lymphocytes was associated with manageable toxicity consistent with individual agents. Further evaluation of this combination therapy in mice with advanced RCC is required. In conclusion, cellular immunotherapy and oncolytic therapy for cancer may be improved by the synergistic effects of lenvatinib and sensitized lymphocytes. In the present study, the inherent antineoplastic and immune stimulatory properties of the two agents were enhanced when used in combination, which may provide a basis for clinical treatment of patients with RCC.

A multi-target protein of hTERTR-FAM96A presents significant anticancer potent in the treatment of hepatocellular carcinoma

The abilities to escape apoptosis induced by anticancer drugs are an essential factor of carcinogenesis and a hallmark of resistance to cancer therapy. In this study, we identified hTERTR-FAM96A (human telomerase reverse transcriptase–family with sequence similarity 96 member A) as a new efficient agent for apoptosome-activating and anti-tumor protein and investigated the potential tumor suppressor function in hepatocellular carcinoma. The hTERTR-FAM96A fusion protein was constructed by genetic engineering and its anticancer function of hTERTR-FAM96A was explored in vitro and in vivo by investigating the possible preclinical outcomes. Effects of hTERTR-FAM96A on improvement of apoptotic sensitivity and inhibition of migration and invasion were examined in cancer cells and tumors. Our results showed that the therapeutic effects of hTERTR-FAM96A were highly effective for inhibiting tumor growth and inducing apoptosis of hepatocellular carcinoma cells in H22-bearing nude mice. The hTERTR-FAM96A fusion protein could specifically bind with Apaf-1 and hTERT, which further induced apoptosis of hepatocellular carcinoma cells and improved apoptosis sensitivity. Our results indicated that hTERTR-FAM96A treatment enhanced cytotoxic effects by upregulation of cytotoxic T lymphocyte responses, interferon-γ release, and T lymphocyte infiltration. In addition, hTERTR-FAM96A led to tumor-specific immunologic cytotoxicity through increasing apoptotic body on hepatocellular tumors. Furthermore, hTERTR-FAM96A dramatically inhibited tumor growth, reduced death rate, and prolonged mice survival in hepatocellular carcinoma mice derived from three independent hepatocellular carcinoma mice cohorts compared to control groups. In summary, our data suggest that hTERTR-FAM96A may serve as an efficient anti-tumor agent for the treatment of hepatocellular carcinoma.

Towards targeted combinatorial therapy design for the treatment of castration-resistant prostate cancer

BACKGROUND

Prostate cancer is one of the most prevalent cancers in males in the United States and amongst the leading causes of cancer related deaths. A particularly virulent form of this disease is castration-resistant prostate cancer (CRPC), where patients no longer respond to medical or surgical castration. CRPC is a complex, multifaceted and heterogeneous malady with limited standard treatment options.

RESULTS

The growth and progression of prostate cancer is a complicated process that involves multiple pathways. The signaling network comprising the integral constituents of the signature pathways involved in the development and progression of prostate cancer is modeled as a combinatorial circuit. The failures in the gene regulatory network that lead to cancer are abstracted as faults in the equivalent circuit and the Boolean circuit model is then used to design therapies tailored to counteract the effect of each molecular abnormality and to propose potentially efficacious combinatorial therapy regimens. Furthermore, stochastic computational modeling is utilized to identify potentially vulnerable components in the network that may serve as viable candidates for drug development.

CONCLUSION

The results presented herein can aid in the design of scientifically well-grounded targeted therapies that can be employed for the treatment of prostate cancer patients.

Src inhibition potentiates antitumoral effect of paclitaxel by blocking tumor-induced angiogenesis

The protein kinase Src is frequently over-activated in advanced cancers where it modulates the signaling transduction cascade of several growth factors. The feasibility of combination treatment of Src inhibitors with chemotherapy is currently under investigation. We evaluated the anti-tumoral effect of paclitaxel (PTX) in combination with S13, a tyrosine kinase inhibitor with a prevalent specificity for Src, in a hormone-insensible prostate cancer (PCa) cell model. In vivo, combination treatment with PTX and S13 reduced dramatically PCa tumor growth with a relevant difference in the density of new blood vessels with respect to control and single treatments. This reduction was determined by a concomitant impairment of endothelial cell migration and of VEGF release by cancer cells. In fact, S13, when used alone, was sufficient to reduce tubule formation in vivo, and to inhibit VEGFR2 activation and FAK expression in endothelial cells. In addition, the combination treatment determined a significant reduction in ROS production and HIF-1 stabilization in PCa cells respect to single treatments with S13 or PTX. In conclusion, Src-inhibition could be an effective therapeutic strategy aimed at supporting the anti-angiogenic action of PTX in aggressive PCa.

Influence of peripheral whole-blood microRNA-7 and microRNA-221 high expression levels on the acquisition of castration-resistant prostate cancer: evidences from in vitro and in vivo studies

Prostate cancer (PC) is the more frequently diagnosed neoplasia in men in developed countries. The evolution of PC to castration-resistant prostate cancer (CRPC) represents real problems of clinical management, in consequence to the limited therapeutic options. MicroRNAs (miRNAs) are small noncoding RNAs that play an important role in gene expression and function regulation. The increased evidence that miRNAs are involved in cancer development and progression has made them potential biomarkers for cancer diagnosis, prognosis, and aggressiveness. Our purpose was to identify a miRNA expression profile associated with the development of CRPC. We firstly observed a miRNA expression profile differentially expressed between the castration-resistant (CR) PC3 cell line and the hormone-sensitive LnCaP cell line, where miR-7, miR-221, and miR-222 were upregulated in PC3 (11.3-fold increase, P = 0.012; 11.3-fold increase, P = 0.002; 8.6-fold increase, P = 0.002, respectively). We also observed that the trend of miR-1233 expression levels was higher in PC3 (3.7-fold increase, P = 0.057). These miRNAs differentially expressed in vitro were studied in a peripheral whole-blood samples from PC patients. We observed that patients presenting an early CR acquisition (≤ 20 months) had higher expression levels of miR-7 and miR-221 (P = 0.034 and P = 0.036, respectively). Furthermore, we found that patients diagnosed with high-Gleason score tumors and presenting simultaneous higher miR-7 expression levels have a significant reduce time to CR compared with patients who present lower miR-7 expression levels (11 vs. 51 months, log-rank test P = 0.004). We also found that patients diagnosed with high-Gleason score tumors and higher expression levels of miR-221 have an early CRPC compared to patients with lower miR-221 expression levels (10 vs. 46 months, log-rank test P = 0.012). We observed a significantly lower overall survival in patients with higher peripheral whole-blood expression levels of miR-7 (28 vs. 116 months, log-rank test P = 0.001). Our results suggest that miR-7 and miR-221 peripheral whole-blood expression levels can be potential predictive biomarkers of CRPC development.

Molecular signatures in urologic tumors

Urologic tumors continue to represent a huge fraction of cancer cases in the United States, with over 376,310 estimated new diagnoses in 2013. As with many types of tumors, urologic tumors vary greatly in their phenotype, ranging from minimally invasive to malignancies possessing great metastatic potential. The increasing need for more efficient and less invasive methods of cancer detection, as well as the ability to predict severity of the disease phenotype is readily evident--yet reliable methods remain elusive in a clinical setting today. Comprehensive panels of gene clusters are being developed toward the generation of molecular signatures in order to better diagnose urologic malignancies, and identify effective treatment strategies in the emerging era of personalized medicine. In this review, we discuss the current literature on the credibility and biomarker value of such molecular signatures in the context of clinical significance relating to the pathological aggressiveness of urologic tumors (prostate, bladder and renal cancer)--also exploiting their predictive potential in the response to treatment.

New platinum(II) complexes conjugated at position 7α of 17β-acetyl-testosterone as new combi-molecules against prostate cancer: design, synthesis, structure-activity relationships and biological evaluation

Prostate cancer is a major public health problem worldwide and, more specifically, new treatments for hormone-refractory cancers are highly sought by several research groups. Although platinum(II)-based chemotherapy and other strategies grow in interest to treat castration-resistant prostate cancer (CRPC), they still exhibit modest activity on CRPC and overall patient survival. In this study, we designed and prepared new combi-molecules using 17β-acetyl-testosterone and amino acid platinum(II) complexes linked at the position 7α to target and to improve the antiproliferative activity of platinum(II)-based chemotherapy on prostate cancer cells. Twelve chemical intermediates and six new combi-molecules were prepared and characterized. Structure-activity relationships studies show that the platinum complex moiety is essential for an optimal cytocidal activity. Moreover, stereochemistry of the amino acid involved in the platinum complexes had only minor effects on the antiproliferative activity whereas pyridinyl (10a and b) and thiazolyl (10f) complexes exhibited the highest cytocidal activities that are significantly superior to that of cisplatin used as control on human prostate adenocarcinoma LNCaP (AR+), PC3 (AR-) and DU145 (AR-). Compounds 10a, b and f arrested the cell cycle progression in S-phase and induced double strand breaks as confirmed by the phosphorylation of histone H2AX into γH2AX. Compounds 10a and f showed 33 and 30% inhibition, respectively of the growth of HT-1080 tumors grafted onto chick chorioallantoic membranes. Finally, compounds 10a and 10f exhibited low toxicity on the chick embryos (18 and 21% of death, respectively), indicating that these new combi-molecules might be a promising new class of anticancer agents for prostate cancer.

Improvement of a predictive model of castration-resistant prostate cancer: functional genetic variants in TGFβ1 signaling pathway modulation

Prostate cancer (PC) is the most frequently diagnosed cancer in men. The acquisition of castration-resistant (CR) phenotype is associated with the activation of signaling pathways mediated by growth factors. The TGFβ1 and its receptors have an important role in tumor progression, being the pro-apoptotic function modulated by the expression of TGFBR2. A single nucleotide polymorphism -875 G > A in TGFBR2 gene has been described, which may influence the expression levels of the receptor. Our purpose was to investigate the potential role of TGFBR2-875G>A in PC risk and in the response to androgen deprivation therapy (ADT). TGFBR2-875G>A polymorphism was studied by allelic discrimination using real-time polymerase chain reaction (PCR) in 891 patients with PC and 874 controls. A follow-up study was undertaken to evaluate response to ADT. The TGFBR2 and SMAD7 mRNA expression were analyzed by a quantitative real-time PCR. We found that TGFBR2-875GG homozygous patients present lower expression levels of TGFBR2 mRNA (AA/AG: 2(-ΔΔCT) =1.5, P=0.016). GG genotype was also associated with higher Gleason grade (OR=1.51, P=0.019) and increased risk of an early relapse after ADT (HR=1.47, P=0.024). The concordance (c) index analysis showed that the definition of profiles that contains information regarding tumor characteristics associated with genetic information present an increased capacity to predict the risk for CR development (c-index model 1: 0.683 vs model 2: 0.736 vs model 3: 0.746 vs model 4: 0.759). The TGFBR2-875G>A contribution to an early relapse in ADT patients, due to changes in mRNA expression, supports the involvement of TGFβ1 pathway in CRPC. Furthermore, according to our results, we hypothesize the potential benefits of the association of genetic information in predictive models of CR development.

Molecular interplay between cdk4 and p21 dictates G0/G1 cell cycle arrest in prostate cancer cells

This study examined the effect of 3, 9-dihydroxy-2-prenylcoumestan (pso), a furanocoumarin, on PC-3 and C4-2B castration-resistant prostate cancer (CRPC) cell lines. Pso caused significant G0/G1 cell cycle arrest and inhibition of cell growth. Molecular analysis of cyclin (D1, D2, D3, and E), cyclin-dependent kinase (cdk) (cdks 2, 4, and 6), and cdk inhibitor (p21 and p27) expression suggested transcriptional regulation of the cdk inhibitors and more significant downregulation of cdk4 than of cyclins or other cdks. Overexpression of cdk4, or silencing of p21 or p27, overcame pso-induced G0/G1 arrest, suggesting that G0/G1 cell cycle arrest is a potential mechanism of growth inhibition in CRPC cells.

Aldo-keto reductase family 1 member C3 (AKR1C3) is a biomarker and therapeutic target for castration-resistant prostate cancer

Current endocrine treatment for advanced prostate cancer does not result in a complete ablation of adrenal androgens. Adrenal androgens can be metabolized by prostate cancer cells, which is one of the mechanisms associated with progression to castration-resistant prostate cancer (CRPC). Aldo-keto reductase family 1 member C3 (AKR1C3) is a steroidogenic enzyme that plays a crucial role in the conversion of adrenal androgen dehydroepiandrosterone (DHEA) into high-affinity ligands for the androgen receptor (testosterone [T] and dihydrotestosterone [DHT]). The aim of this study was to examine whether AKR1C3 could be used as a marker and therapeutic target for CRPC. AKR1C3 mRNA and protein levels were upregulated in CRPC tissue, compared with benign prostate and primary prostate cancer tissue. High AKR1C3 levels were found only in a subset of CRPC patients. AKR1C3 can be used as a biomarker for active intratumoral steroidogenesis and can be measured in biopsy or transurethral resection of the prostate specimens. DuCaP (a CRPC cell line that has high AKR1C3 expression levels) used and converted DHEA under hormone-depleted conditions into T and DHT. The DHEA-induced growth of DuCaP could be antagonized by indomethacine, an inhibitor of AKR1C3. This study indicates that AKR1C3 can be considered a therapeutic target in a subgroup of patients with high AKR1C3 expression.

Current management of prostate cancer: dilemmas and trials

The past decade has witnessed significant advances in our understanding of the biology of prostate cancer. Androgen ablation/androgen receptor inhibition remains as the mainstay of treatment for advanced prostate cancer. Our understanding of the biology of prostate cancer has increased exponentially owing to advances in molecular biology. With this knowledge many intriguing issues have come to light, which clinicians and scientists alike strive to answer. These include why prostate cancer is so common, what drives the development of prostate cancer at a molecular level, why prostate cancer appears refractory to many families of cytotoxic chemotherapeutics, and why prostate cancer preferentially metastasizes to bone. Two clinical forms of prostate cancer have been identified: indolent organ confined disease, which elderly men often die of, and aggressive metastatic disease. A method of distinguishing between these two forms of the disease at an organ-confined stage remains elusive. Understanding the mechanisms of castrate resistance is a further issue of clinical importance. New trials of treatments, including molecular agents that target prostate cancer from a range of angles, have been instituted over the past 10-15 years. We can look at these trials not only as a chance to investigate the effectiveness of new treatments but also as an opportunity to further understand the complex biology of this disease.

Upregulated FGFR1 expression is associated with the transition of hormone-naive to castrate-resistant prostate cancer

BACKGROUND

Prostate cancer (PC) represents a global health issue. Treatment for locally advanced and metastatic PC remains unsatisfactory. The androgen receptor (AR) has been validated in having a key role in both naïve and castrate-resistant PC (CRPC). However, the significance of other signalling pathways in CRPC is less well validated.

METHODS

To gain a better insight into the molecular signalling cascades involved in clinical CRPC, we performed gene expression profiling using the Illumina DASL assay and studied matched hormone-naive (HN) and CR prostate tumours (n=10 pairs). Ingenuity Pathways Analysis (IPA) was used to identify potential networks involved, and further validation was performed in in vitro cell models and clinical tumours.

RESULTS

Expression of 50 genes was significantly different between HN and CRPC. IPA revealed two networks of particular interest, including AR and FGFR1, respectively. FGFR1 expression was confirmed to be significantly upregulated in CRPC (P ≤ 0.005), and abnormal FGFR1 expression was associated with shorter time to biochemical relapse in HNPC (P=0.006) and less favourable disease-specific survival in CRPC (P=0.018).

CONCLUSION

For the first time, our gene expression profiling experiment on archival tumour materials has identified upregulated FGFR1 expression to be associated with PC progression to the CR state.