TMPRSS2:ERG fusion gene occurs less frequently in Chinese patients with prostate cancer

Prostate cancer treatment - China's perspective

Prostate cancer (PCa) incidence and mortality have rapidly increased in China. Notably, unique epidemiological characteristics of PCa are found in the Chinese PCa population, including a low but rising incidence and an inferior but improving disease prognosis. Consequently, the current treatment landscape of PCa in China demonstrates distinct features. Establishing a more thorough understanding of the characteristics of Chinese patients may help provide novel insights into potential treatment strategies for PCa patients. Herein, we review the epidemiological status and differences in treatment modalities of Chinese PCa patients. In addition, we discuss the underlying socioeconomic and biological factors that contribute to such diversity and further propose directions for future efforts in optimizing the PCa treatment in China.

RNA-based biomarkers for the diagnosis, prognosis, and therapeutic response monitoring of prostate cancer

Prostate cancer (CaP) is the most common malignant neoplasm of the urinary tract. The current recommendations for CaP diagnosis rely on the prostate-specific antigen levels and a digital rectal examination for anatomical abnormalities. However, these diagnostic tools are not highly sensitive. In particular, prostate-specific antigen has a low positive predictive value (approximately 30%). Thus, there is a need to develop biomarkers to improve the early clinical detection of CaP. Several novel technologies enable the identification of biomarkers from diverse sources, including the urine, serum, and prostate tissues. Furthermore, advances in genomic techniques have enabled the analysis of novel biomarkers, such as deoxyribonucleic acids (DNAs), ribonucleic acids (RNAs), proteins, and circulating tumor cells. Previous studies have demonstrated that RNAs are potential diagnostic biomarkers for various cancers using high-throughput sequencing analysis. The sensitivity and specificity of RNA biomarkers are higher than those of protein biomarkers. Polymerase chain reaction enables the amplification of trace levels of RNAs with high sensitivity and specificity. RNA biomarkers provide dynamic insights into cellular states and regulatory processes when compared with DNA biomarkers. Additionally, multiple copies of various RNAs in a cell provide more information than DNA. The levels of specific RNAs in CaP tissues are upregulated when compared with those in non-cancerous tissues. Additionally, RNAs can be easily isolated from various body fluids. Thus, RNAs are potential non-invasive biomarkers for CaP. Moreover, the analysis of RNA levels adjusted for each stage of CaP enables the determination of prognostic individualized therapy for aggressive or progressive CaP. This review focused on the diagnostic and prognostic values of RNAs for CaP.

Comparative study of immunohistochemical expression of ERG and MAGI2 in prostatic carcinoma

Diagnosis of Prostatic adenocarcinoma (PAC) is still a problematic issue. The objective of this study was to evaluate the diagnostic and prognostic value of ERG immunohistochemical (IHC) expression compared to MAGI2.

MATERIALS AND METHODS

This study was conducted on 56 cases of PAC and 29 cases of nodular prostatic hyperplasia (NPH). IHC staining for ERG and MAGI2 was applied to archival formalin-fixed paraffin-embedded blocks. Semi-quantitative scoring was compared and correlated with clinicopathologic parameters and the Ki-67 index.

RESULTS

Revealed positive ERG in 51.8% of PAC while all NPH cases were negative. On the other hand, MAGI2 was detected in 91.1% of PAC versus 17.2% of NPH. Using ROC curve, the ERG showed 53.6% sensitivity, 100% specificity, 76.5% diagnostic accuracy (DA) and area under the ROC curve 0.768 in comparison to MAGI2 that showed (91.1%, 86.2%, 88.25% and 0.948 respectively). Analysis of the combined use of the two markers revealed 95% sensitivity, 100% specificity, and 94% DA when tested synchronously. Moreover, a statistically significant inverse relationship could be detected between ERG expression and the Gleason grading group (P = 0.01) and Ki-67 index (P < 0.001). In addition, high-grade prostatic intraepithelial neoplasia (HGPIN) adjacent to carcinoma; showed positive expressions in (1/11 cases, 9.11%) for ERG and (6/11 cases, 54%) for MAGI2.

CONCLUSION

This study recommends using both ERG and MAGI2 in a cocktail for better diagnostic validity of PAC. Only ERG expression could be a good prognostic indicator.

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.

Biological Aspects of Cancer Health Disparities

Racial and ethnic disparities span the continuum of cancer care and are driven by a complex interplay among social, psychosocial, lifestyle, environmental, health system, and biological determinants of health. Research is needed to identify these determinants of cancer health disparities and to develop interventions to achieve cancer health equity. Herein, we focus on the overall burden of ancestry-related molecular alterations, the functional significance of the alterations in hallmarks of cancer, and the implications of the alterations for precision oncology and immuno-oncology. In conclusion, we reflect on the importance of estimating ancestry, improving diverse racial and ethnic participation in cancer clinical trials, and examining the intersection among determinants of cancer health disparities.

Molecular characterization of prostate cancer in Middle Eastern population highlights differences with Western populations with prognostic implication

BACKGROUND

To investigate the incidence and prognostication of ERG, PTEN and SPINK1 protein expressions in prostate cancer cohort of Middle Eastern descent in comparison to published data from Western population.

METHODS

Immunohistochemistry for ERG, PTEN and SPINK1 was performed in a cohort of localized PCA (n = 340). The data were correlated to pathological and clinical outcomes and compared to Western populations.

RESULTS

ERG expression and PTEN loss were noted in 123/288 (42.7%) and 91/297 (30.6%) of patients, respectively. SPINK1 expression was assessed in a subset of cases, noted in 6/150 (4%) of patients. Only ERG expression was associated with grade groups, being more common in the lower grade groups (1-3 vs 4-5; p = 0.04). In contrast to the Western population, PTEN loss foci were more likely to be ERG negative, observed in 81% of tumor foci and patients with PTEN neg/ERG pos were more likely to exhibit biochemical recurrence (OR 2.831; 95% CI 1.10-726, p = 0.03). This association remained significant in multivariate analysis (OR 2.68; 95% CI 0.98-7.33, p = 0.05), after adjusting for GG, path stage and surgical margin.

CONCLUSION

This study documents significant differences in key molecular events in PCA in Middle Eastern population compared to Western populations that could explain differences in PCA incidence, progression and prognostication. ERG, PTEN and SPINK1 genomic alteration occur less frequently and the enrichment of ERG for PTEN loss is not observed. Additionally, patients with combined PTEN loss/ERG positive are at highest risk for BCR vs North American Caucasian population where PTEN loss alone seems to be associated with the worst clinical outcome. The data presented here further support differences in clonal evolution between Middle Eastern and Western population in relation to PCA and add further insight to understanding PCA molecular pathways.

ERG Tumor Type is Less Frequent in High Grade and High Stage Prostate Cancers of Chinese Men

Background: The incidence of prostatic adenocarcinoma has been rapidly increasing among Chinese men. This alarming trend prompted evaluations of early causal genomic alterations known to drive prostate tumorigenesis. Recurrent activation of the ETS-Related Gene (ERG) by genomic rearrangements is the most recognized early event in prostate cancer. Following the initial detection of ERG rearrangement at gene expression and genomic and levels, development of diagnostic quality antibodies against ERG oncoprotein have streamlined the rapid assessment of ERG frequencies world-wide. Unexpectedly, these studies revealed highest frequencies of ERG among Caucasian descents, lower frequencies among African Americans and even lower prevalence of ERG among Asian men.

Objective: To asses in a prospective study ERG frequencies, clinico-pathological and prognostic associations of ERG among prostate cancer patients of the Dalian region of Northeast China, by an established immunohistochemical procedure that have been used in studies world-wide.

Methods: Formalin fixed paraffin embedded specimens donated by patients (N=50) diagnosed with prostatic adenocarcinoma who underwent transurethral resection of the prostate (TURP) between 2007 and 2012 were evaluated for ERG by immunohistochemistry.

Results: Of the 50 cases, 13/50 (26.0%) tumors were positive for ERG. In all cases, normal prostatic epithelial were ERG negative. ERG was more frequently detected in the lower Gleason score (≤7) and low T-stage. Consistent with reports from Asian countries the results of our study shows lower overall frequencies of ERG positive tumors when compared to reports from Western countries.

Conclusion: The intriguing association of even lower ERG frequencies with high Gleason scores and higher T-stages provides impetus for current driver gene discoveries focused on the predominantly ERG negative prostate cancers of Asian men.

Urinary markers aiding in the detection and risk stratification of prostate cancer

The purpose of this review is to highlight the role of existing and promising urinary biomarkers for the detection and prognostication of prostate cancer (PCa). A number of novel urinary biomarkers have been introduced into the clinical space, which in combination with clinical variables, have demonstrated an increased ability to select patients for biopsy and identify men at risk of harboring clinically significant PCa. Though a number of assays require further validation, initial data is promising and forthcoming results will ultimately determine their clinical utility and commercial availability. For the past 30 years, first-line screening for PCa has relied on measurement of serum prostate-specific antigen (PSA) levels and the results from a digital rectal exam (DRE). A large body of evidence from the last 3 decades indicates that these screening methods are problematic, and often inadequate for detecting clinically significant PCa. Extensive efforts have recently been made to identify and commercialize novel PCa biomarkers for more effective detection of PCa, either alone or in combination with current screening methods. This review article highlights problems with current screening standards, and discusses 6 urinary biomarker assays in terms of their ability to detect and risk-stratify PCa: prostate cancer antigen 3 (PCA3), TMPRSS2-ERG, second chromosome locus associated with prostate-1 (SChLAP1), ExoDx, SelectMDx, and Michigan Prostate Score (MiPS).

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.

Prostate cancer in Jordanian-Arab population: ERG status and relationship with clinicopathologic characteristics

TMPRSS2/ERG fusion was found to be the most common genetic event in prostate adenocarcinoma. There is a strong correlation between the fusion and ERG-positive immunostaining. Many studies showed racial variation in ERG expression in prostate cancer patients. There is no data however on the rate of ERG-positive cancer in Jordanian or Arab population. We evaluated the frequency and the significance of ERG fusion in Jordanian-Arab population using immunohistochemistry for ERG. The cohort included 193 prostate cancer specimens: 109 needle core biopsies, 45 radical prostatectomies, 37 transurethral resections of prostate, and 2 enucleation specimens. We found ERG reactivity in 64 (33.2%) of evaluated cases. The observed ERG frequency in the Jordanian-Arab population is lower than the one documented in North America, but it is higher than in Asian patient cohorts. The ERG positivity was significantly associated with lower baseline prostate-specific antigen but was unrelated to patient age, Gleason Score, or the novel Gleason Grade Groups. In the 45 prostatectomy cases, ERG did not correlate with the pathologic stage, margin, nodal status, and the biochemical recurrence, and it did not appear to represent an important prognosticator.

Expression of ERG Protein and TMRPSS2-ERG Fusion in Prostatic Carcinoma in Egyptian Patients

AIM

Prostate cancer (PCa) is the second most common cancers in men worldwide. Its incidence can be influenced by several risk factors including genetic susceptibility. Therefore the search for the expression of a certain gene (ERG) and its rearrangement could give us clues for proper identification of PCa. And the study of ERG expression and its comparison to FISH in Egyptian patients can show whether ERG immunophenotype could be used instead of FISH, as it is cheaper.

MATERIALS AND METHODS

This study was performed on 85 cases of PCa, showing 30 cases with HGPIN and 30 cases of prostatic hyperplasia. All were immunohistochemistry stained using ERG monoclonal rabbit antihuman antibody was used (clone: EP111). FISH analysis was performed in 38 biopsies of PCa cases to detect TMRPSS2-ERG rearrangement using the FISH ZytoLight TriCheck Probe (SPEC TMRPSS2-ERG).

RESULTS

ERG expression was found in 26% of PCa cases and 20% of HGPIN cases. FISH analysis showed fusion of 21 cases of PCa (out of 22 cases showing ERG immunoexpression).

CONCLUSION

Our findings emphasise that only malignant and pre-malignant cells and not benign cells from the prostate stain positive. ERG expression may offer a simpler, accurate and less costly alternative for evaluation of ERG fusion status in PCa.