A high-density tissue microarray from patients with clinically localized prostate cancer reveals ERG and TATI exclusivity in tumor cells

PTEN, ERG, SPINK1, and TFF3 Status and Relationship in a Prostate Cancer Cohort from Jordanian Arab Population

Background and Objectives: Prognostic biomarkers in prostate cancer (PCa) include PTEN, ERG, SPINK1, and TFF3. Their relationships and patterns of expression in PCa in developing countries, including Jordan, have not yet been investigated. Materials and Methods: A tissue microarray (TMA) of PCa patients was taken from paraffin-embedded tissue blocks for 130 patients. PTEN, ERG, SPINK1, and TFF3 expression profiles were examined using immunohistochemistry (IHC) and correlated with each other and other clinicopathological factors. Results: PTEN loss of any degree was observed in 42.9% of PCa cases. ERG and TFF3 were expressed in 59.3% and 46.5% of PCa cases, respectively. SPINK1 expression was observed in 6 out of 104 PCa cases (5.4%). Among all PCa cases (n = 104), 3.8% (n = 4) showed SPINK1+/ERG+ phenotype, 1.9% (n = 2) showed SPINK1+/ERG- phenotype, 56.7% (n = 59) showed SPINK1-/ERG+ phenotype, and 37.5% showed SPINK1-/ERG- phenotype (n = 39). Among ERG positive cases (n = 63), 6.3% were SPINK1 positive. Among SPINK1 positive cases (n = 6), 66.7% were ERG positive. SPINK1 expression was predominantly observed in a subgroup of cancers that expressed TFF3 (6/6). Additionally, a statistically significant loss of PTEN expression was observed from Gleason Score 6 (GS6) (Grade Group 1 (GG1)) to GS9-10 (GG5); (p-value 0.019). Conclusions: This is the first study to look at the status of the PTEN, ERG, SPINK1, and TFF3 genes in a Jordanian Arab population. Loss of PTEN has been linked to more aggressive prostate cancer with high GSs/GGs. SPINK1 expression was predominantly observed in a subgroup of cancers that expressed TFF3. Our results call for screening these biomarkers for grading and molecular subtyping of the disease.

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.

Molecular Underpinnings Governing Genetic Complexity of ETS-Fusion-Negative Prostate Cancer

Inter- and intra-patient molecular heterogeneity of primary and metastatic prostate cancer (PCa) confers variable clinical outcome and poses a formidable challenge in disease management. High-throughput integrative genomics and functional approaches have untangled the complexity involved in this disease and revealed a spectrum of diverse aberrations prevalent in various molecular subtypes, including ETS fusion negative. Emerging evidence indicates that SPINK1 upregulation, mutations in epigenetic regulators or chromatin modifiers, and SPOP are associated with the ETS-fusion negative subtype. Additionally, patients with defects in a DNA-repair pathway respond to poly-(ADP-ribose)-polymerase (PARP) inhibition therapies. Furthermore, a new class of immunogenic subtype defined by CDK12 biallelic loss has also been identified in ETS-fusion-negative cases. This review focuses on the emerging molecular underpinnings driving key oncogenic aberrations and advancements in therapeutic strategies of this disease.

Ductal adenocarcinoma of the prostate: Clinical and biological profiles

BACKGROUND

Ductal adenocarcinoma (DAC) is a rare and aggressive subtype of prostate cancer (PCa). In the present study, we analyzed the clinical and biological characteristics of DAC, in comparison with high grade conventional acinar PCa.

METHODS

Samples and data were retrospectively collected from seven institutions and centrally reviewed. Immunohistochemistry was performed on tissue microarrays to assess the expression of candidate proteins, based on the molecular classification of PCa, including ERG, PTEN, and SPINK1. SPOP mutations were investigated from tumor DNA by Sanger sequencing. Relationships with outcome were analyzed using log-rank analysis and multivariable Cox regression.

RESULTS

Among 56 reviewed prostatectomy specimens, 45 cases of DAC were finally confirmed. The pathological stage was pT3 in more than 66% of cases. ERG was expressed in 42% of DAC, SPINK1 in 9% (all ERG-negative), and two cases (ERG-negative) harbored a SPOP mutation. Compared to high grade conventional PCa matched for the pathological stage, cell proliferation was higher (P = 0.04) in DAC, and complete PTEN loss more frequent (P = 0.023). In multivariate analysis, SPINK1 overexpression (P = 0.017) and loss of PSA immunostaining (P = 0.02) were significantly associated with biochemical recurrence.

CONCLUSION

these results suggest that, despite biological differences that highlighted DAC aggressiveness, the molecular classification recently proposed in conventional PCa could also be applied in DAC.

The association between SPINK1 and clinical outcomes in patients with prostate cancer: a systematic review and meta-analysis

Evidence of the prognostic role of serine peptidase inhibitor Kazal type 1 (SPINK1) in prostate cancer (PCa) is controversial. The aim of this study was, therefore, to evaluate the association between SPINK1 and clinical outcomes in PCa. Searches were made of PubMed, Medline, Embase, and the China Biology Medicine disc (CBMdisc) up to January 2017. The Newcastle–Ottawa Scale was used to assess the risk of bias of included studies. RevMan software was used to perform meta-analysis, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) method was employed for assessing the quality of the evidence. Ten studies with 17,161 patients were included in the analysis. Random-effect models were adopted for all outcomes with significant heterogeneities. In patients treated with radical prostatectomy, SPINK1 was associated with biochemical recurrence (BCR) (hazard ratio [HR] =1.41, 95% confidence interval [CI]: 1.01–1.97; P=0.04), but not PCa-specific mortality (HR =0.93, 95% CI: 0.33–2.57; P=0.88), and overall survival (OS) (HR =0.89, 95% CI: 0.58–1.35; P=0.57). In metastatic PCa, SPINK1 was significantly associated with castration-resistant PCa-free survival (HR =3.87, 95% CI: 1.87–8.00; P=0.0003) and OS (HR =2.59, 95% CI: 1.16–5.78; P=0.02). However, the quality of the evidence was very low for all study outcome measures. In conclusion, although SPINK1 was not a predictor of PCa mortality or OS among patients who underwent radical prostatectomy, it may have prognostic value in metastatic PCa.

Molecular subtyping of prostate cancer

PURPOSE OF REVIEW

The recent publication of The Cancer Genome Atlas molecular taxonomy of primary prostate cancer highlights the increased understanding of the genomic basis of human prostate cancer, but also emphasizes the complexity and heterogeneity of prostate cancer.

RECENT FINDINGS

Seven molecular subclasses have been defined on the basis of early genomic alterations, which are largely mutually exclusive.

SUMMARY

We review the recent advances in the genomic understanding of human prostate cancer, with focus on molecular subclassification. Broadly, prostate cancer can be classified based upon whether specific genomic rearrangements, such as the Transmembrane Protease, Serine 2-ETS-related gene fusion occur or whether specific alterations such as Speckle-type POZ protein and forkhead box A1 mutations occur. The molecular drivers remain to be identified in a further quarter of human prostate cancers. Depending upon the molecular subclassification and the coincident genomic alterations, specific clinical insights can be gained from this information, including associations with pathologic factors, race, and prognosis, as well as the possibility for future precision therapies.

SPINK1 Overexpression in Localized Prostate Cancer: a Rare Event Inversely Associated with ERG Expression and Exclusive of Homozygous PTEN Deletion

SPINK1 is proposed as potential prognostic marker in prostate cancer (PCA). However, its relation to PTEN and ERG in localized PCA remains unclear. The study population consisted of two independent cohorts of men treated by radical prostatectomy for localized PCA (discovery n = 218 and validation n = 129). Patterns of association between SPINK1 and each of ERG and PTEN were evaluated by immunohistochemistry and fluorescence in situ hybridization. Associations between SPINK1 expression and various pathologic parameters and clinical outcome were also investigated. SPINK1 was expressed in 15.3 % and 10.9 % of cases in the discovery and validation cohort, respectively. SPINK expression was observed in 5.56 % of high-grade prostatic intraepithelial neoplasia and 1.1 % of adjacent morphologically benign prostatic glands. SPINK1 and ERG expression were almost exclusive, with only 1.0 % of the cases co-expressing both in the same core sample. SPINK1 interfocal and within-core heterogeneity was noted in 29.2 % and 64.6 % of cases, respectively. SPINK1 expression was not significantly associated with PTEN deletion in the two cohorts (p = 0.871 for discovery cohort and p = 0.293 for validation cohort). While SPINK1 expression did occur with hemizygous PTEN deletion, there was a complete absence of SPINK1 expression in PCA showing homozygous PTEN deletion, which was confirmed in the validation cohort (p = 0.02). Despite SPINK1's association with higher Gleason score (>7) (p = 0.02), it was not associated with other pathological parameters or biochemical recurrence post-radical prostatectomy. We documented absolute exclusivity between SPINK1 overexpression and homozygous PTEN deletion in localized PCA. SPINK1 and ERG expressions are exclusive events in PCA. SPINK1 is not of added prognostic value in localized PCA.

Estandarización del protocolo para la detección de las fusiones TMPRSS2:ERG y de la expresión de los genes EZH2, SPINK-1 y NKX3.1 en cáncer de próstata (CaP)

En la actualidad no existe una herramienta que permita diferenciar pacientes con cáncer de próstata (CaP) de mal pronóstico de aquellos con enfermedad indolente que sólo requieren un seguimiento controlado de la enfermedad. Debido a la coexistencia de diferentes focos premalignos y malignos en el CaP, el entendimiento sobre el proceso de carcinogénesis requiere de un mejor conocimiento. Actualmente, la heterogeneidad morfológica en CaP es evaluada con la puntuación de Gleason, la cual está fuertemente relacionada con el pronóstico de la enfermedad, sin embargo, esto es insuficiente por lo que se trabaja actualmente en identificación de alteraciones moleculares que permitan identificar subtipos que puedan establecer de manera más precisa el pronóstico del paciente. Este estudio preliminar buscó la estandarización del método de cuantificación en muestras prostáticas de FFPE de la expresión de los transcritos de posibles biomarcadores, como los oncogenes SPINK-1 y EZH2, el supresor tumoral NKX3.1, en conjunto con la determinación de la presencia/ausencia del gen de fusión TMPRSS2:ERG, ya que estos transcritos se encuentran involucrados en aparentes eventos excluyentes de la evolución natural del CaP, que apoyan la posibilidad de una clasificación molecular para esta enfermedad.

Serine protease inhibitor Kazal type 1 (SPINK1) drives proliferation and anoikis resistance in a subset of ovarian cancers

Ovarian cancer represents the most lethal tumor type among malignancies of the female reproductive system. Overall survival rates remain low. In this study, we identify the serine protease inhibitor Kazal type 1 (SPINK1) as a potential therapeutic target for a subset of ovarian cancers. We show that SPINK1 drives ovarian cancer cell proliferation through activation of epidermal growth factor receptor (EGFR) signaling, and that SPINK1 promotes resistance to anoikis through a distinct mechanism involving protease inhibition. In analyses of ovarian tumor specimens from a Mayo Clinic cohort of 490 patients, we further find that SPINK1 immunostaining represents an independent prognostic factor for poor survival, with the strongest association in patients with nonserous histological tumor subtypes (endometrioid, clear cell, and mucinous). This study provides novel insight into the fundamental processes underlying ovarian cancer progression, and also suggests new avenues for development of molecularly targeted therapies.

SPINK1 expression in relation to PTEN and ERG in matched primary and lymph node metastatic prostate cancer: Implications for biomarker development

BACKGROUND

SPINK1, ERG, and PTEN are proposed prognostic biomarkers in prostate cancer (PCA). However, their relations and patterns of expression in primary and metastatic lymph node (LN) PCAs are not fully explored.

METHODS

A tissue microarray of matched primary PCA and LN metastasis was constructed from 36 patients. SPINK1, ERG, and PTEN expression statuses were assessed by immunohistochemistry and correlated with each other.

RESULTS

SPINK1 and ERG were expressed in 25% and 42.7% of primary PCA cases, respectively. PTEN loss of any degree was observed in 91.7% of primary PCA cases, with 54.2% showing complete loss. In primary PCA, 12.5% of the cases showed SPINK1+/ERG-phenotype, 16.7% showed SPINK1+/ERG+phenotype, 25.0% showed SPINK1-/ERG+phenotype, and 45.8% showed SPINK1-/ERG-phenotype. All PCAs with expression of either SPINK1 or ERG also exhibited PTEN loss, whereas PCA without PTEN loss (2 cases) expressed neither SPINK1 nor ERG. In primary PCA, evaluation of combined ERG and SPINK1 status, but not SPINK1 individually, was associated with a significant difference in proportion of Gleason patterns (P = 0.013), with the SPINK1+/ERG+and SPINK1-/ERG-phenotypes represented more in Gleason pattern>7 PCAs. In LN metastases, the overall SPINK1 protein expression frequency was significantly lower (6.5% of cases) compared with primary PCA (P = 0.03). Only 16.7% of cases with positive SPINK1 expression in primary PCA maintained expression in LN metastases. The down-regulated SPINK1 expression in LN was primarily because of a reduction in the SPINK1+/ERG+PCA subpopulation to 3.5% of cases (P = 0.16 compared with primary PCA). The frequencies of ERG expression and PTEN loss were relatively stable in primary PCA and LN metastases.

CONCLUSION

SPINK1 expression is dynamically regulated with up-regulation in primary sites of nodal metastatic PCA and down-regulation in LN metastases. The increased SPINK1 expression in primary site of nodal metastatic PCA is secondary to an increased frequency of SPINK1+/ERG+tumors. In primary PCAs, the SPINK1+/ERG+phenotype is associated with higher Gleason grade, suggesting that this phenotype may mark a more aggressive PCA subpopulation with higher risk of LN metastases.

Correlation of ERG immunohistochemistry with molecular detection of TMPRSS2-ERG gene fusion

Aims

TMPRSS2/E26 transformation-specific (ETS) family gene fusion in prostate carcinoma (PCa) can be detected by several methods including immunohistochemistry (IHC) for ETS-related gene (ERG), the diagnostic utility of which has not been clearly defined.

Methods

We explored TMPRSS2-ERG gene rearrangement status in 132 patients with PCa with four detection methods including fluorescence in situ hybridisation for TMPRSS2-ERG fusion, real-time reverse transcription PCR (RT-qPCR) for ERG and TMPRSS-ERG fusion transcript mRNA and IHC for ERG.

Results

Concordant results were found in 126 cases for the four detection methods and the remaining six cases showed discrepancy in one method: two cases in IHC, three cases in RT-qPCR for ERG and one case in RT-qPCR for fusion transcript. In discordant cases, the majority results were determined as final fusion status. Analysis of discrepancy cases for ERG IHC showed that weak immunoreactivity for ERG should be regarded as equivocal and that even strong immunoreactivity can be false positive. The overall incidence of TMPRSS-ERG gene fusion was 24%.

Conclusions

ERG IHC is a useful surrogate test for the detection of TMPRSS2-ERG gene fusion, but it needs to be interpreted with caution and definite judgement should not be based on IHC alone. A relatively low incidence of TMPRSS2-ERG gene fusion was demonstrated in this Korean cohort.

SPINK1 Promoter Variants Are Associated with Prostate Cancer Predisposing Alterations in Benign Prostatic Hyperplasia Patients

BACKGROUND/AIM

Several studies reported that patients with benign prostatic hyperplasia (BPH) experienced a 10% increased incidence of prostate cancer (PCa) after the first 5 years of diagnosis. We investigated the association between single nucleotide polymorphisms (SNPs) in the promoter of Serine Protease Inhibitor Kazal Type 1 (SPINK1) and the increased risk of BPH and PCa.

MATERIALS AND METHODS

We genotyped three SNPs in a cases-control study, including BPH and PCa cases. Multiple logistic regression models were applied to analyze clinical and genotypic data.

RESULTS

We found an inverse association between SNP rs10035432 and BPH under the log-additive (p=0.007) model. No association was found between these SNPs and PCa risk. However, we observed a possible association between rs1432982 and lower-grade PCa (p=0.05) under the recessive model.

CONCLUSION

SPINK1 promoter variants are likely to be associated with the risk of BPH.

Clinical value of ERG, TFF3, and SPINK1 for molecular subtyping of prostate cancer

BACKGROUND

In view of the marked molecular heterogeneity of prostate cancer (PCa), clinical and pathologic parameters alone may be unreliable for predicting disease outcomes after surgical intervention. The development of biomarkers may be helpful to estimate tumor heterogeneity and stratify patients in terms of their risk of progression. Levels of v-ets avian erythroblastosis virus E26 oncogene homolog (ERG), trefoil factor 3 (TFF3), and serine peptidase inhibitor, Kazal type 1 (SPINK1) are commonly elevated in PCa, but it is unclear whether the evaluation of these 3 markers can help to discriminate patients who will have different clinical outcomes. The authors investigated whether assessment of ERG, TFF3, and SPINK1 expression could help to define clinically relevant, distinct subsets of patients with PCa.

METHODS

The cohort consisted of 279 men with PCa who underwent radical prostatectomy at Henri Mondor Hospital. Expression levels of ERG, TFF3, and SPINK1 were evaluated immunohistochemically in the prostatectomy specimens. Potential associations of ERG, TFF3, and SPINK1 with age, prostate-specific antigen (PSA), tumor stage, Gleason score, and biochemical recurrence, defined by PSA failure, were investigated.

RESULTS

Although prognostic significance was not observed for ERG or TFF3, an exclusive pattern of expression was demonstrated for TFF3 and ERG. SPINK1 expression was observed exclusively in a subgroup of cancers that expressed TFF3 (41 of 175 tumors). Moreover, SPINK1 positivity was identified as predictive of biochemical recurrence in univariate (P = .0009) and multivariate (P = .0003) analyses.

CONCLUSIONS

The current results suggest that ERG and TFF3 characterize 2 distinct subsets of PCa, with a more aggressive subgroup of TFF3-expressing tumors that express SPINK1. Together, these findings support a rationale of screening for these biomarkers for prognostic purposes and molecular subtyping of the disease.

Evidence for molecular differences in prostate cancer between African American and Caucasian men

PURPOSE

The aim of this study was to compare the frequency of ERG rearrangement, PTEN deletion, SPINK1 overexpression, and SPOP mutation in prostate cancer in African American and Caucasian men.

EXPERIMENTAL DESIGN

Dominant tumor nodules from radical prostatectomy specimens of 105 African American men (AAM) were compared with 113 dominant nodules from Caucasian men (CaM). Clinical and pathologic characteristics of the two groups were similar. SPINK1 overexpression was evaluated by immunohistochemistry, ERG rearrangement and PTEN deletion by FISH, and SPOP mutation by Sanger sequencing.

RESULTS

ERG rearrangement was identified in 48 of 113 tumors (42.5%) in CaM and 29 of 105 tumors (27.6%) in AAM (P = 0.024). PTEN deletion was seen in 19 of 96 tumors (19.8%) in CaM and 7 of 101 tumors (6.9%) in AAM (P = 0.011). SPINK1 overexpression was present in 9 of 110 tumors (8.2%) in CaM and 25 of 105 tumors (23.4%) in AAM (P = 0.002). SPOP mutation was identified in 8 of 78 (10.3%) tumors in CaM and 4 of 88 (4.5%) tumors in AAM (P = 0.230). When adjusted for age, body mass index, Gleason score, and pathologic stage, ERG rearrangement and SPINK1 overexpression remain significantly different (P = 0.018 and P = 0.008, respectively), and differences in PTEN deletion and SPOP mutation approach significance (P = 0.061 and P = 0.087, respectively).

CONCLUSIONS

Significant molecular differences exist between prostate cancers in AAM and CaM. SPINK1 overexpression, an alteration associated with more aggressive prostate cancers, was more frequent in AAM, whereas ERG rearrangement and PTEN deletion were less frequent in this cohort. Further investigation is warranted to determine whether these molecular differences explain some of the disparity in incidence and mortality between these two ethnic groups.

Prostate cancer SubtyPINg biomarKers and outcome: is clarity emERGing?

Molecular prostate cancer subtypes have been proposed on the basis of mutually exclusive SPINK1 and ERG overexpression, with conflicting reports on their prognostic ability. Flavin and colleagues report that SPINK1 is neither prognostic nor absolutely mutually exclusive with ERG, raising important questions about prostate cancer molecular subtyping and prognostic biomarker evaluation.

Serine protease inhibitor Kazal type 1 promotes epithelial-mesenchymal transition through EGFR signaling pathway in prostate cancer

BACKGROUND

Overexpression of serine protease inhibitor Kazal type 1 (SPINK1) defines an aggressive molecular subtype of ETS fusion-negative prostate cancer (PCa) patients in western countries. However, how SPINK1 contributes to PCa invasion and metastasis is largely unknown.

METHODS

Fluorescence in situ hybridization and immunohistochemistry were utilized to detect ERG rearrangement, SPINK1 expression, and EGFR aberrations in a cohort of 211 PCa patients with radical prostatectomy. Real-time quantitative PCR and Western blotting were used to study the transcript and protein expression levels. Cellular distribution of E-cadherin and vimentin were observed by immunofluorescence. Cellular function was evaluated by siRNA, transwell, and wound healing assay, respectively.

RESULTS

SPINK1-induced Epithelial-mesenchymal transition (EMT) in benign prostate RWPE cells, manifested by acquisition of mesenchymal morphology, alternation of EMT markers as well as migration and invasion capabilities. Knockdown of SPINK1 in 22RV1 PCa cells results in up-regulation of E-cadherin and down-regulation of vimentin. SPINK1-induced EMT is mediated by EGFR, in which MAPK/MEK/ERK pathway is mainly involved. Connective tissue growth factor (CTGF) might be an important down-stream molecule of SPINK1-EGFR axis. Clinically, SPINK1 and EGFR were significantly co-overexpressed in a cohort of Chinese PCa patients (n > 200). SPINK1 is an unfavorable prognostic factor in Chinese PCas (P = 0.025).

CONCLUSIONS

These findings suggest that SPINK1 promotes EMT through EGFR signaling pathway in PCa and SPINK1 could be a new prognostic marker in Chinese PCas.

HOXB13 G84E-related familial prostate cancers: a clinical, histologic, and molecular survey

Recent genetic epidemiologic studies identified a germline mutation in the homeobox transcription factor, HOXB13 G84E, which is associated with markedly increased risk for prostate cancer, particularly early-onset hereditary prostate cancer. The histomorphologic and molecular features of cancers arising in such carriers have not been studied. Here, we reviewed prostatectomy specimens from 23 HOXB13 G84E mutation carriers, mapping the total cancer burden by anatomically distinct cancer focus and evaluating morphologic features. We also assessed basic molecular subtypes for all cancer foci (ERG/SPINK1 status) by dual immunohistochemistry staining on full sections. The cohort showed a median age of 58 years, a median serum PSA level of 5.7 ng/mL, and a median of 6 cancer foci (range, 1 to 14) per case. Of evaluable cases, dominant foci were Gleason score 6 in 23%, 3+4=7 in 41%, 4+3=7 in 23%, and ≥8 in 14%; biochemical recurrence was observed in 1 case over a median of 36 months follow-up. Histologic review found a high prevalence of cases showing cancers with a spectrum of features previously described with pseudohyperplastic carcinomas, with 45% of cases showing a dominant focus with such features. Molecular subtyping revealed a strikingly low prevalence of ERG cancer with increased prevalence of SPINK1 cancer (dominant focus ERG 17%, SPINK1 26%, ERG/SPINK1 52%, single ERG/SPINK1 focus 4%). One ERG/SPINK1 dominant focus showed aberrant p63 immunophenotype. In summary, HOXB13 G84E variant-related prostate cancers show frequent pseudohyperplastic-type features and markedly low prevalence of ERG cancers relative to unselected cases and, especially, to early-onset cohorts. These findings suggest that novel molecular pathways may drive disease in HOXB13 G84E carriers.

SPINK1 protein expression and prostate cancer progression

PURPOSE

SPINK1 overexpression has been described in prostate cancer and is linked with poor prognosis in many cancers. The objective of this study was to characterize the association between SPINK1 overexpression and prostate cancer-specific survival.

EXPERIMENTAL DESIGN

The study included 879 participants in the U.S. Physicians' Health Study and Health Professionals Follow-Up Study, diagnosed with prostate cancer (1983-2004) and treated by radical prostatectomy. Protein tumor expression of SPINK1 was evaluated by immunohistochemistry on tumor tissue microarrays.

RESULTS

Seventy-four of 879 (8%) prostate cancer tumors were SPINK1 positive. Immunohistochemical data were available for PTEN, p-Akt, pS6, stathmin, androgen receptor (AR), and ERG (as a measure of the TMPRSS2:ERG translocation). Compared with SPINK1-negative tumors, SPINK1-positive tumors showed higher PTEN and stathmin expression, and lower expression of AR (P < 0.01). SPINK1 overexpression was seen in 47 of 427 (11%) ERG-negative samples and in 19 of 427 (4%) ERG-positive cases (P = 0.0003). We found no significant associations between SPINK1 status and Gleason grade or tumor stage. There was no association between SPINK1 expression and biochemical recurrence (P = 0.56). Moreover, there was no association between SPINK1 expression and prostate cancer mortality (there were 75 lethal cases of prostate cancer during a mean of 13.5 years follow-up; HR = 0.71; 95% confidence interval, 0.29-1.76).

CONCLUSIONS

Our results suggest that SPINK1 protein expression may not be a predictor of recurrence or lethal prostate cancer amongst men treated by radical prostatectomy. SPINK1 and ERG protein expression do not seem to be entirely mutually exclusive, as some previous studies have suggested.

The mutational landscape of prostate cancer

CONTEXT

Prostate cancer (PCa) is a clinically heterogeneous disease with marked variability in patient outcomes. Molecular characterization has revealed striking mutational heterogeneity that may underlie the variable clinical course of the disease.

OBJECTIVE

In this review, we discuss the common genomic alterations that form the molecular basis of PCa, their functional significance, and the potential to translate this knowledge into patient care.

EVIDENCE ACQUISITION

We reviewed the relevant literature, with a particular focus on recent studies on somatic alterations in PCa.

EVIDENCE SYNTHESIS

Advances in sequencing technology have resulted in an explosion of data regarding the mutational events underlying the development and progression of PCa. Heterogeneity is the norm; few abnormalities in specific genes are highly recurrent, but alterations in certain signaling pathways do predominate. These alterations include those in pathways known to affect tumorigenesis in a wide spectrum of tissues, such as the phosphoinositide 3-kinase/phosphatase and tensin homolog/Akt pathway, cell cycle regulation, and chromatin regulation. Alterations more specific to PCa are also observed, particularly gene fusions of ETS transcription factors and alterations in androgen signaling. Mounting data suggest that PCa can be subdivided based on a molecular profile of genetic alterations.

CONCLUSIONS

Major advances have been made in cataloging the genomic alterations in PCa and understanding the molecular mechanisms underlying the disease. These findings raise the possibility that PCa could soon transition from being a poorly understood, heterogeneous disease with a variable clinical course to being a collection of homogenous subtypes identifiable by molecular criteria, associated with distinct risk profiles, and perhaps amenable to specific management strategies or targeted therapies.