Increased association of the ERG oncoprotein expression in advanced stages of prostate cancer in Filipinos

Metabolic pathways enriched according to ERG status are associated with biochemical recurrence in Hispanic/Latino patients with prostate cancer

BACKGROUND

The role of ERG-status molecular subtyping in prognosis of prostate cancer (PCa) is still under debate. In this study, we identified differentially expressed genes (DEGs) according to ERG-status to explore their enriched pathways and implications in prognosis in Hispanic/Latino PCa patients.

METHODS

RNA from 78 Hispanic PCa tissues from radical prostatectomies (RP) were used for RNA-sequencing. ERG_high /ERG_low tumor groups were determined based on the 1.5-fold change median expression in non-tumor samples. DEGs with a False Discovery Rate (FDR) < 0.01 and a fold change >2 were identified between ERG_high and ERG_low tumors and submitted to enrichment analysis in MetaCore. Survival and association analyses were performed to evaluate biochemical recurrence (BCR)-free survival.

RESULTS

The identification of 150 DEGs between ERG_high and ERG_low tumors revealed clustering of most of the non-BCR cases (60%) into de ERG_high group and most of the BCR cases (60.8%) in ERG_low group. Kaplan-Meier survival curves showed a worst BCR-free survival for ERG_low patients, and a significant reduced risk of BCR was observed for ERG_high cases (OR = 0.29 (95%CI, 0.10-0.8)). Enrichment pathway analysis identified metabolic-related pathways, such as the renin-angiotensin system and angiotensin maturation system, the linoleic acid metabolism, and polyamines metabolism in these ERG groups.

CONCLUSIONS

ERG_low tumor cases were associated with poor BCR-free survival in our Hispanic/Latino patients, with metabolism-related pathways altered in the BCR progression.

IMPACT

Our findings suggest the need to dissect the role of diet, metabolism, and lifestyle as risk factors for more aggressive PCa subtypes.

Prevalence and clinical application of TMPRSS2-ERG fusion in Asian prostate cancer patients: a large-sample study in Chinese people and a systematic review

Fusion between the transmembrane protease serine 2 and v-ets erythroblastosis virus E26 oncogene homolog (TMPRSS2-ERG fusion) is a common genetic alteration in prostate cancer among Western populations and has been suggested as playing a role in tumorigenesis and progression of prostate cancer. However, the prevalence of TMPRSS2-ERG fusion differs among different ethnic groups, and contradictory results have been reported in Asian patients. We aim to evaluate the prevalence and significance of TMPRSS2-ERG fusion as a molecular subtyping and prognosis indicator of prostate cancer in Asians. We identified the fusion status in 669 samples from prostate biopsy and radical prostatectomy by fluorescence in situ hybridization and/or immunohistochemistry in China. We examined the association of TMPRSS2-ERG fusion with clinicopathological characteristics and biochemical recurrence by Chi-square test and Kaplan–Meier analysis. Finally, a systematic review was performed to investigate the positive rate of the fusion in Asian prostate cancer patients. McNemar's test was employed to compare the positive rates of TMPRSS2-ERG fusion detected using different methods. The positive rates of TMPRSS2-ERG fusion were 16% in our samples and 27% in Asian patients. In our samples, 9.4% and 19.3% of cases were recognized as fusion positive by fluorescence in situ hybridization and immunohistochemistry, respectively. No significant association between the fusion and clinical parameters was observed. TMPRSS2-ERG fusion is not a frequent genomic alteration among Asian prostate cancer patients and has limited significance in clinical practices in China. Besides ethnic difference, detection methods potentially influence the results showing a positive rate of TMPRSS2-ERG fusion.

Molecular profiling of radical prostatectomy tissue from patients with no sign of progression identifies ERG as the strongest independent predictor of recurrence

BACKGROUND

As a major cause of morbidity and mortality among men, prostate cancer is a heterogenous disease, with a vast heterogeneity in the biology of the disease and in clinical outcome. While it often runs an indolent course, local progression or metastasis may eventually develop, even among patients considered "low risk" at diagnosis. Therefore, biomarkers that can discriminate aggressive from indolent disease at an early stage would greatly benefit patients. We hypothesized that tissue specimens from early stage prostate cancers may harbor predictive signatures for disease progression.

METHODS

We used a cohort of radical prostatectomy patients with longitudinal follow-up, who had tumors with low grade and stage that revealed no signs of future disease progression at surgery. During the follow-up period, some patients either remained indolent (non-BCR) or progressed to biochemical recurrence (BCR). Total RNA was extracted from tumor, and adjacent normal epithelium of formalin-fixed-paraffin-embedded (FFPE) specimens. Differential gene expression in tumors, and in tumor versus normal tissues between BCR and non-BCR patients were analyzed by NanoString using a customized CodeSet of 151 probes.

RESULTS

After controlling for false discovery rates, we identified a panel of eight genes (ERG, GGT1, HDAC1, KLK2, MYO6, PLA2G7, BICD1 and CACNAID) that distinguished BCR from non-BCR patients. We found a clear association of ERG expression with non-BCR, which was further corroborated by quantitative RT-PCR and immunohistochemistry assays.

CONCLUSIONS

Our results identified ERG as the strongest predictor for BCR and showed that potential prognostic prostate cancer biomarkers can be identified from FFPE tumor specimens.

Ethnicity and ERG frequency in prostate cancer

Emerging observations emphasize a distinct biology of prostate cancer among men of different ethnicities and races, as demonstrated by remarkable differences in the frequency of ERG oncogenic activation, one of the most common and widely studied prostate cancer driver genes. Worldwide assessment of ERG alterations frequencies show consistent trends, with men of European ancestry having the highest rates of alteration and men of African or Asian ancestries having considerably lower alteration rates. However, data must be interpreted cautiously, owing to variations in assay platforms and specimen types, as well as ethnic and geographical classifications. Many opportunities and challenges remain in assessing cancer-associated molecular alterations at a global level, and these need to be addressed in order to realize the true potential of precision medicine for all cancer patients.

TMPRSS2-ERG gene fusion in Turkish patients with localized prostate cancer: results of radical prostatectomy specimens

OBJECTIVE

Our aim was to evaluate and determine the frequency of Transmembrane protease, serine 2 (TMPRSS2)-ERG fusion in Turkish patients with clinically localized prostate cancer by using immunohistochemistry and reveal its relationship with clinicopathologic variables.

MATERIAL AND METHODS

Radical prostatectomy specimens of 99 patients, who underwent radical retropubic prostatectomy for localized cancer, between January 2002 and December 2011 were analyzed in the study. To detect ERG fusions, monoclonal ERG antibodyclone ID: EPR3864 (Epitomics, San Diego, CA, USA) and monoclonal anti-ERG antibody (9FY) (BiocareMedical, LLC, USA) were used. The immunistochemical expression of ERG protein was assessed as positive or negative regardless of stain intensity. Patients' age, total and primary Gleason scores, PSA levels, prostate volumes, tumor volumes, tumor stages and perineural invasion status were analysed retrospectively. Total fusion rate and correlation between the variables and fusion were evaluated.

RESULTS

Mean age, prostate volume, tumor volume, PSA value of 99 patients were 62.02 years (±5.93), 50.02 cc (±20.67), 3.19 cc (±4.16), and 9.34 ng/mL (±3.37) respectively. TMPRSS2-ERG fusion was seen in 46 (46.5%) of 99 patients. When the variables analysed with independent samples t test to predict fusion (+) status, none of them was found to be statistically significant. When evaluated by logistic regression analysis for (+) or (-) status, only tumor stage was found to be statistically significantly correlated with fusion (p=0.049).

CONCLUSION

The incidence of TMPRSS-ERG fusion in patients with localised prostate cancer in our study with Turkish population was found as 46.5%. Only tumor stage correlated with TMPRSS2-ERG fusion.

Molecular profiling of ETS and non-ETS aberrations in prostate cancer patients from northern India

BACKGROUND

Molecular stratification of prostate cancer (PCa) based on genetic aberrations including ETS or RAF gene-rearrangements, PTEN deletion, and SPINK1 over-expression show clear prognostic and diagnostic utility. Gene rearrangements involving ETS transcription factors are frequent pathogenetic somatic events observed in PCa. Incidence of ETS rearrangements in Caucasian PCa patients has been reported, however, occurrence in Indian population is largely unknown. The aim of this study was to determine the prevalence of the ETS and RAF kinase gene rearrangements, SPINK1 over-expression, and PTEN deletion in this cohort.

METHODS

In this multi-center study, formalin-fixed paraffin embedded (FFPE) PCa specimens (n = 121) were procured from four major medical institutions in India. The tissues were sectioned and molecular profiling was done using immunohistochemistry (IHC), RNA in situ hybridization (RNA-ISH) and/or fluorescence in situ hybridization (FISH).

RESULTS

ERG over-expression was detected in 48.9% (46/94) PCa specimens by IHC, which was confirmed in a subset of cases by FISH. Among other ETS family members, while ETV1 transcript was detected in one case by RNA-ISH, no alteration in ETV4 was observed. SPINK1 over-expression was observed in 12.5% (12/96) and PTEN deletion in 21.52% (17/79) of the total PCa cases. Interestingly, PTEN deletion was found in 30% of the ERG-positive cases (P = 0.017) but in only one case with SPINK1 over-expression (P = 0.67). BRAF and RAF1 gene rearrangements were detected in ∼1% and ∼4.5% of the PCa cases, respectively.

CONCLUSIONS

This is the first report on comprehensive molecular profiling of the major spectrum of the causal aberrations in Indian men with PCa. Our findings suggest that ETS gene rearrangement and SPINK1 over-expression patterns in North Indian population largely resembled those observed in Caucasian population but differed from Japanese and Chinese PCa patients. The molecular profiling data presented in this study could help in clinical decision-making for the pursuit of surgery, diagnosis, and in selection of therapeutic intervention.