[Emerging biomarkers for the diagnosis, staging and prognosis of prostate cancer]

Proteomic Profiling of Serum-Derived Exosomes from Ethnically Diverse Prostate Cancer Patients

Prostate cancer (PCa) remains the most frequently diagnosed male malignancy in Western countries and the second most common cause of male cancer death in the United States. The relatively elevated PCa incidence and mortality among African American men makes this cancer type a challenging health disparity disease. To increase the chance for successful trea tment, earlier detection and prediction of tumor aggress iveness will be important and need to be resolved. This study demonstrates that small membrane-bound vesicles shed from the tumor called exosomes contain ethnically and tumor-specific biomarkers, and could be exploited for their diagnostic and therapeutic potential.

Significant association of alpha-methylacyl-CoA racemase gene polymorphisms with susceptibility to prostate cancer: a meta-analysis

BACKGROUND

Alpha-methylacyl-CoA racemase(AMACR) is thought to play key roles in diagnosis and prognosis of prostate cancer. However, studies of associations between AMACR gene polymorphisms and prostate cancer risk reported inconsistent results. Therefore, we conducted the present meta-analysis to clarify the link between AMACR gene polymorphisms and prostate cancer risk.

MATERIALS AND METHODS

A literature search was performed in PubMed, Embase, China National Knowledge Infrastructure (CNKI), Wanfang and Weipu databases. Odds ratios (ORs) and 95% confidence intervals (95%CIs) were calculated to assess the strength of any association between AMACR polymorphisms and prostate cancer risk. Subgroup analyses by ethnicity, source of controls, quality control and sample size were also conducted.

RESULTS

Five studies covering 3,313 cases and 3,676 controls on five polymorphisms (D175G, M9V, S201L, K277E and Q239H) were included in this meta-analysis. Significant associations were detected between prostate cancer and D175G (dominant model: OR=0.89, 95%CI=0.80-0.99, P=0.04) and M9V (dominant model: OR=0.87, 95%CI=0.78-0.97, P=0.01) polymorphisms as well as that in subgroup analyses. We also observed significant decreased prostate cancer risk in the dominant model (OR=0.90, 95%CI=0.81-0.99, P=0.04) for the S201L polymorphism. However, K277E and Q239H polymorphisms did not appear to be related to prostate cancer risk.

CONCLUSIONS

The current meta- analysis indicated that D175G and M9V polymorphisms of the AMACR gene are related to prostate cancer. The S201L polymorphism might also be linked with prostate cancer risk to some extent. However, no association was observed between K277E or Q239H polymorphisms and susceptibility to prostate cancer.

[Choice of new drugs in castration-resistant prostate cancer: predictive factors and effectiveness assessment]

INTRODUCTION

Docetaxel has been the cornerstone in the treatment of castration- resistant prostate cancer (CRPC) since 2004. The recent and almost simultaneous arrival of new and effective molecules - several of which are already available on the market - has added to the CRPC treatment arsenal. Several studies have explored the optimal order in which these new treatments should be administered. The aim of this review was to present their respective predictive and evaluative factors and suggest potential administration sequences.

METHODS

The PubMed medical literature citations database was searched using the following key words: prostate cancer, castration resistant, metastatic, targeted therapy, treatment sequence, immunotherapy and clinical trials. The reports of the most recent European and North American congresses were also included.

RESULTS

While no predictive factors have been clearly identified for these new therapies to date, a Gleason score of not less than 8 and one or more chemotherapy sessions seemed to be predictive of lower efficacy for abiraterone. Promising elements for further investigation include the circulating tumour cell count and variation in this count per treatment, ERG mutation status or the intratumoural androgen status. Substitution criteria have not yet been reported but, as is the case with all hormone therapies, changes in PSA levels emerge as a valuable indicator of the efficacy of abiraterone. The best treatment sequence for patients who develop castration-resistance remains to be defined.

CONCLUSION

Although new molecules have recently become available, the experience with their use is limited. Thus, no predictive markers of response rates and treatment outcomes or data concerning the best treatment sequence to use in patients with CRPC are as yet available.

Plasma-derived exosomal survivin, a plausible biomarker for early detection of prostate cancer

Background

Survivin is expressed in prostate cancer (PCa), and its downregulation sensitizes PCa cells to chemotherapeutic agents in vitro and in vivo. Small membrane-bound vesicles called exosomes, secreted from the endosomal membrane compartment, contain RNA and protein that they readily transport via exosome internalization into recipient cells. Recent progress has shown that tumor-derived exosomes play multiple roles in tumor growth and metastasis and may produce these functions via immune escape, tumor invasion and angiogenesis. Furthermore, exosome analysis may provide novel biomarkers to diagnose or monitor PCa treatment.

Methods

Exosomes were purified from the plasma and serum from 39 PCa patients, 20 BPH patients, 8 prostate cancer recurrent and 16 healthy controls using ultracentrifugation and their quantities and qualities were quantified and visualized from both the plasma and the purified exosomes using ELISA and Western blotting, respectively.

Results

Survivin was significantly increased in the tumor-derived samples, compared to those from BPH and controls with virtually no difference in the quantity of Survivin detected in exosomes collected from newly diagnosed patients exhibiting low (six) or high (nine) Gleason scores. Exosome Survivin levels were also higher in patients that had relapsed on chemotherapy compared to controls.

Conclusions

These studies demonstrate that Survivin exists in plasma exosomes from both normal, BPH and PCa subjects. The relative amounts of exosomal Survivin in PCa plasma was significantly higher than in those with pre-inflammatory BPH and control plasma. This differential expression of exosomal Survivin was seen with both newly diagnosed and advanced PCa subjects with high or low-grade cancers. Analysis of plasma exosomal Survivin levels may offer a convenient tool for diagnosing or monitoring PCa and may, as it is elevated in low as well as high Gleason scored samples, be used for early detection.