FISH analysis of 107 prostate cancers shows that PTEN genomic deletion is associated with poor clinical outcome

Small cell neuroendocrine prostate cancer with adenocarcinoma components-case report and literature review

Background

Small cell neuroendocrine prostate cancer (SCNC) is a rare aggressive type of neuroendocrine prostate cancer (NEPC) characterized by aggressive clinical course and lack of response to hormone therapy.

Case Description

We present a case report of a 60-year-old man diagnosed with a histologically confirmed primary metastatic (bone, lymph nodes and visceral) SCNC with small components of an adenocarcinoma with clinical symptoms mimicking an acute prostatitis. Of note, serum based neuroendocrine markers (carcinoembryonic antigen, chromogranin A) were negative and the patient had a prostate-specific antigen (PSA) elevation. Genetic testing of tumor tissue revealed breast cancer gene 2 (BRCA2) copy number loss and a retinoblastoma gene (RB1) mutation reflecting again the aggressiveness of the disease. Germline testing for the BRCA2 copy number loss was unremarkable. After 6 cycles of carboplatin and etoposide in combination with androgen deprivation therapy (ADT) the Eastern Cooperative Oncology Group (ECOG) performance status has improved from 3 to 0, in addition the patient was free of pain. In line with clinical improvement, both prostate-specific membrane antigen (PSMA) and fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) revealed a significant reduction of metastatic load. Currently, the patient is treated with ADT plus apalutamide.

Conclusions

We demonstrate for the first time a case of a primary metastatic SCNC with adenocarcinoma components successfully treated by the combination of platinum-based chemotherapy plus hormonal therapy. In addition, we provide a literature overview on management of SCNC as there is no standard treatment established for this disease.

Amplification of different satellite-DNAs in prostate cancer

In various solid tumors and corresponding cell lines, prior research has identified acquired copy number variations (CNVs) encompassing centromeric satellite-DNA sequences. This observation emerged from the application of centromeric probes (satellite-DNA) as controls in molecular cytogenetic investigations and diagnostics, although these accounts were largely anecdotal. In this study, we conducted a systematic screening for satellite-DNA sequence amplification in 31 prostate cancer (PCa) samples, a prevalent malignancy in men characterized by discernible molecular cytogenetic aberrations. Notably, PCa-typical genetic aberrations, such as TMPRSS2-ERG gene rearrangements and PTEN deletion, were identified in 12 and 6 out of the 31 PCa samples, respectively. Overall, PCa exhibited genomic instability marked by chromosomal gain or loss of signals across nearly all tested satellite-DNA regions, with particular emphasis on the Y-chromosome (18/31 cases). Remarkably, 5/12 PCa samples representing more advanced metastatic cancer displayed amplification of one or two satellite DNA stretches each, being detectable as blocks analogous to homogenously staining regions. Notably, these stretches included α-satellite DNA derived from chromosomes 2, 3, 4, 15, and 20, as well as satellite-III DNAs (D1Z1 and DYZ1). These findings align with recent discoveries indicating that α-satellite DNAs are expressed as long-non-coding RNAs in advanced cancer, particularly in the context of PCa.

Real-World Overall Survival and Treatment Patterns by PTEN Status in Metastatic Castration-Resistant Prostate Cancer

PURPOSE

It is estimated that the PTEN tumor suppressor gene is functionally lost in 40%-50% of patients with metastatic castration-resistant prostate cancer (mCRPC). There is limited information on the prognostic significance of PTEN status identified with genomic testing. This real-world cohort study assessed PTEN as a genetic biomarker using data from US-based oncology practices.

METHODS

This retrospective real-world cohort study used a deidentified US-based metastatic prostate cancer clinicogenomic database linked to longitudinal clinical data derived from electronic health records. Patients were aged 18 years and older and diagnosed with mCRPC between January 1, 2018, and June 30, 2021. Comprehensive genomic profiling (CGP) of tumor specimens was performed using next-generation sequencing. First-line (1L) and second-line (2L) treatment patterns were assessed and stratified by PTEN status. Kaplan-Meier methods and a multivariable Cox model were used to compare the real-world overall survival by PTEN status among patients who received 1L novel hormone therapy or taxanes.

RESULTS

In patients with mCRPC who underwent CGP, PTEN loss of function (LOF) was associated with decreased survival compared with intact PTEN (hazard ratio, 1.61 [95% CI, 1.07 to 2.42]; P = .024). The results were not influenced by 1L treatment type. 1L treatment patterns were similar between intact PTEN and PTEN LOF subgroups, with abiraterone and enzalutamide being the two most common treatments in both groups. Patients with PTEN LOF were less likely to receive 2L treatments than patients with intact PTEN.

CONCLUSION

PTEN LOF, identified with genomic testing, was associated with decreased survival and negative prognoses in patients with mCRPC.

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 complexity of intraductal carcinoma of the prostate

Intraductal carcinoma of the prostate (IDC-P) is an aggressive subtype of prostate cancer characterized by the growth of tumor cells within the prostate ducts. It is often found alongside invasive carcinoma and is associated with poor prognosis. Understanding the molecular mechanisms driving IDC-P is crucial for improved diagnosis, prognosis, and treatment strategies. This review summarizes the molecular characteristics of IDC-P and their prognostic indications, comparing them to conventional prostate acinar adenocarcinoma, to gain insights into its unique behavior and identify potential therapeutic targets.

A DNA copy number alteration classifier as a prognostic tool for prostate cancer patients

BACKGROUND

Distinguishing between true indolent and potentially life-threatening prostate cancer is challenging in tumours displaying clinicopathologic features associated with low or intermediate risk of relapse. Several somatic DNA copy number alterations (CNAs) have been identified as potential prognostic biomarkers, but the standard cytogenetic method to assess them has a limited multiplexing capability.

METHODS

Multiplex ligation-dependent probe amplification (MLPA) targeting 14 genes was optimised to survey 448 tumours of patients with low or intermediate risk (Grade Group 1-3, Gleason score ≤7) who underwent radical prostatectomy. A 6-gene CNA classifier was developed using random survival forest and Cox proportional hazard modelling to predict biochemical recurrence.

RESULTS

The classifier score was significantly associated with biochemical recurrence after adjusting for standard clinicopathologic variables and the known prognostic index CAPRA-S score with a hazard ratio of 2.17 and 1.80, respectively (n = 406, P < 0.01). The prognostic value of this classifier was externally validated in published CNA data from three radical prostatectomy cohorts and one radiation therapy pre-treatment biopsy cohort.

CONCLUSION

The 6-gene CNA classifier generated by a single MLPA assay compatible with the small quantities of DNA extracted from formalin-fixed paraffin-embedded (FFPE) tissue specimens has the potential to improve the clinical management of patients with low or intermediate risk disease.

Prognostic Values of Gene Copy Number Alterations in Prostate Cancer

Whilst risk prediction for individual prostate cancer (PCa) cases is of a high priority, the current risk stratification indices for PCa management have severe limitations. This study aimed to identify gene copy number alterations (CNAs) with prognostic values and to determine if any combination of gene CNAs could have risk stratification potentials. Clinical and genomic data of 500 PCa cases from the Cancer Genome Atlas stable were retrieved from the Genomic Data Commons and cBioPortal databases. The CNA statuses of a total of 52 genetic markers, including 21 novel markers and 31 previously identified potential prognostic markers, were tested for prognostic significance. The CNA statuses of a total of 51/52 genetic markers were significantly associated with advanced disease at an odds ratio threshold of ≥1.5 or ≤0.667. Moreover, a Kaplan-Meier test identified 27/52 marker CNAs which correlated with disease progression. A Cox Regression analysis showed that the amplification of MIR602 and deletions of MIR602, ZNF267, MROH1, PARP8, and HCN1 correlated with a progression-free survival independent of the disease stage and Gleason prognostic group grade. Furthermore, a binary logistic regression analysis identified twenty-two panels of markers with risk stratification potentials. The best model of 7/52 genetic CNAs, which included the SPOP alteration, SPP1 alteration, CCND1 amplification, PTEN deletion, CDKN1B deletion, PARP8 deletion, and NKX3.1 deletion, stratified the PCa cases into a localised and advanced disease with an accuracy of 70.0%, sensitivity of 85.4%, specificity of 44.9%, positive predictive value of 71.67%, and negative predictive value of 65.35%. This study validated prognostic gene level CNAs identified in previous studies, as well as identified new genetic markers with CNAs that could potentially impact risk stratification in PCa.

Characterization of exposure–response relationships of ipatasertib in patients with metastatic castration-resistant prostate cancer in the IPATential150 study

Purpose

The exposure–response relationships for efficacy and safety of ipatasertib, a selective AKT kinase inhibitor, were characterized using data collected from 1101 patients with metastatic castration-resistant prostate cancer in the IPATential150 study (NCT03072238).

Methods

External validation of a previously developed population pharmacokinetic model was performed using the observed pharmacokinetic data from the IPATential150 study. Exposure metrics of ipatasertib for subjects who received ipatasertib 400 mg once-daily orally in this study were generated as model-predicted area under the concentration–time curve at steady state (AUC_SS). The exposure–response relationship with radiographic progression-free survival (rPFS) was evaluated using Cox regression and relationships with safety endpoints were assessed using logistic regression.

Results

A statistically significant correlation between ipatasertib AUC_SS and improved survival was found in patients with PTEN-loss tumors (hazard ratio [HR]: 0.92 per 1000 ng h/mL AUC_SS, 95% confidence interval [CI] 0.87–0.98, p = 0.011). In contrast, an improvement in rPFS was seen in subjects receiving ipatasertib treatment (HR: 0.84, 95% CI 0.71–0.99, p = 0.038) but this effect was not associated with ipatasertib AUC_SS in the intention-to-treat population. Incidences of some adverse events (AEs) had statistically significant association with ipatasertib AUC_SS (serious AEs, AEs leading to discontinuation, and Grade ≥ 2 hyperglycemia), while others were associated with only ipatasertib treatment (AEs leading to dose reduction, Grade ≥ 3 diarrhea, and Grade ≥ 2 rash).

Conclusions

The exposure–efficacy results indicated that patients receiving ipatasertib may continue benefiting from this treatment at the administered dose, despite some variability in exposures, while the exposure–safety results suggested increased risks of AEs with ipatasertib treatment and/or increased ipatasertib exposures.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00280-022-04488-2.

PTEN Protein Phosphatase Activity Is Not Required for Tumour Suppression in the Mouse Prostate

Loss PTEN function is one of the most common events driving aggressive prostate cancers and biochemically, PTEN is a lipid phosphatase which opposes the activation of the oncogenic PI3K-AKT signalling network. However, PTEN also has additional potential mechanisms of action, including protein phosphatase activity. Using a mutant enzyme, PTEN Y138L, which selectively lacks protein phosphatase activity, we characterised genetically modified mice lacking either the full function of PTEN in the prostate gland or only lacking protein phosphatase activity. The phenotypes of mice carrying a single allele of either wild-type Pten or Pten^Y138L in the prostate were similar, with common prostatic intraepithelial neoplasia (PIN) and similar gene expression profiles. However, the latter group, lacking PTEN protein phosphatase activity additionally showed lymphocyte infiltration around PIN and an increased immune cell gene expression signature. Prostate adenocarcinoma, elevated proliferation and AKT activation were only frequently observed when PTEN was fully deleted. We also identify a common gene expression signature of PTEN loss conserved in other studies (including Nkx3.1, Tnf and Cd44). We provide further insight into tumour development in the prostate driven by loss of PTEN function and show that PTEN protein phosphatase activity is not required for tumour suppression.

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.

Circular RNAs in prostate cancer: Biogenesis,biological functions, and clinical significance

Circular RNAs (circRNAs) are covalently closed RNA molecules that play important regulatory roles in various tumors. Prostate cancer (PCa) is one of the most common malignant tumors in the world, with high morbidity and mortality. In recent years, more and more circRNAs have been found to be abnormally expressed and involved in the occurrence and development of PCa, including cell proliferation, apoptosis, invasion, migration, metastasis, chemotherapy resistance, and radiotherapy resistance. Most of the circRNAs regulate biological behaviors of cancer through a competitive endogenous RNA (ceRNA) regulatory mechanism, and some can exert their functions by binding to proteins. circRNAs are also associated with many clinicopathological features of PCa, including tumor grade, lymph node metastasis, and distant metastasis. In addition, circRNAs are potential diagnostic and prognostic biomarkers for PCa. Considering their critical regulatory roles in the progression of PCa, circRNAs would be the potential therapeutic targets. In this paper, the current research status of circRNAs in PCa is briefly reviewed.

SPOP and CHD1 alterations in prostate cancer: Relationship with PTEN loss, tumor grade, perineural infiltration, and PSA recurrence

BACKGROUND

In the non-ETS fusion of prostate cancer (PCa) pathway, SPOP mutations emerge as a distinct oncogenic driver subclass. Both SPOP downregulation and mutation can lead to SPOP target stabilization promoting dysregulation of key regulatory pathways. CHD1 gene is commonly deleted in PCa. CHD1 loss significantly co-occurs with SPOP mutations, resulting in a PCa subclass with increased AR transcriptional activity and with a specific epigenetic pattern.

METHODS

In this study, SPOP alterations at mutational and protein levels and CHD1 copy number alterations have been analyzed and correlated with ERG and PTEN protein expression and with the clinical pathological features of the patients.

RESULTS

SPOP protein loss has been detected in 42.9% of the cases, and it has been strongly associated with PTEN protein loss (p < .001). CHD1 gene loss has been detected in 24.5% and SPOP mutations in 5.9% of the cases. Loss of CHD1 has been strongly associated with SPOP mutations (p = .003) and has shown a trend to be associated with ERG wt cancers (p = .08). The loss of SPOP protein (p = .01) and the combination of PTEN and SPOP protein loss (p = .002) were both statistically more common in grade group 5 cancers, with a prevalence of 60% and 37.5%, respectively. Furthermore, SPOP loss/PTEN loss and SPOP wt/PTEN loss phenotypes were strongly associated with extraprostatic perineural infiltration (p = .007). Strong CHD1 loss was associated with a shorter time to PSA recurrence in the univariate (p = .04), and showed a trend to be associated with the PSA recurrence risk in the multivariate analysis (p = .058).

CONCLUSIONS

The results of the present study suggest that the loss of SPOP protein expression, either alone or in combination with loss of PTEN and, on the other hand, a marked loss of the CHD1 gene are very promising prognostic biomarkers in PCa.

Akt isoforms differentially provide for chemoresistance in prostate cancer

OBJECTIVE

Early prostate cancer micrometastatic foci undergo a mesenchymal to epithelial reverting transition, not only aiding seeding and colonization, but also rendering the tumor cells generally chemoresistant. We previously found that upregulated E-cadherin in the epithelial micrometastases activated canonical survival pathways, including PI3K-Akt, that protected the tumor cells from death; however, the extent of protection from blocking the pathway in its entirety was modest, because different isoforms may have alternately affected cell functioning. Here, we characterized Akt isoform expressions in primary and metastatic prostate cancers, as well as their individual contributions to chemoresistance.

METHODS

Akt isoforms and E-cadherin were manipulated with drugs, knocked down, and over expressed. Tumor cell killing was determined in vitro and in vivo. Overall survival was calculated from patient records and specimens.

RESULTS

Pan-Akt inhibition sensitized tumor cells to chemotherapy, and specific blockade of Akt1 or/and Akt2 caused cells to be more chemoresponsive. Overexpression of Akt3 induced apoptosis. A low dose of Akt1 or Akt2 inhibitor enabled standard chemotherapies to significantly eradicate metastatic prostate tumors in a mouse model, acting as chemosensitizers. In human specimens, we found Akt1 and Akt2 positively correlated, whereas Akt3 inversely correlated, with the overall survival of prostate cancer patients. Akt1high/Akt2high/Akt3low tumors had the worst outcomes.

CONCLUSIONS

E-cadherin-induced activation of Akt1/2 isoforms was the essential mechanism of chemoresistance, whereas Akt3 made cells more fragile. These findings emphasized the need to target Akt1/2, rather than pan-Akt, as a rational therapeutic approach.

Cancer stem cell phosphatases

Cancer stem cells (CSCs) are involved in the initiation and progression of human malignancies by enabling cancer tissue self-renewal capacity and constituting the therapy-resistant population of tumor cells. However, despite the exhausting characterization of CSC genetics, epigenetics, and kinase signaling, eradication of CSCs remains an unattainable goal in most human malignancies. While phosphatases contribute equally with kinases to cellular phosphoregulation, our understanding of phosphatases in CSCs lags severely behind our knowledge about other CSC signaling mechanisms. Many cancer-relevant phosphatases have recently become druggable, indicating that further understanding of the CSC phosphatases might provide novel therapeutic opportunities. This review summarizes the current knowledge about fundamental, but yet poorly understood involvement of phosphatases in the regulation of major CSC signaling pathways. We also review the functional roles of phosphatases in CSC self-renewal, cancer progression, and therapy resistance; focusing particularly on hematological cancers and glioblastoma. We further discuss the small molecule targeting of CSC phosphatases and their therapeutic potential in cancer combination therapies.

Tissue- and Liquid-Based Biomarkers in Prostate Cancer Precision Medicine

Worldwide, prostate cancer (PC) is the second-most-frequently diagnosed male cancer and the fifth-most-common cause of all cancer-related deaths. Suspicion of PC in a patient is largely based upon clinical signs and the use of prostate-specific antigen (PSA) levels. Although PSA levels have been criticised for a lack of specificity, leading to PC over-diagnosis, it is still the most commonly used biomarker in PC management. Unfortunately, PC is extremely heterogeneous, and it can be difficult to stratify patients whose tumours are unlikely to progress from those that are aggressive and require treatment intensification. Although PC-specific biomarker research has previously focused on disease diagnosis, there is an unmet clinical need for novel prognostic, predictive and treatment response biomarkers that can be used to provide a precision medicine approach to PC management. In particular, the identification of biomarkers at the time of screening/diagnosis that can provide an indication of disease aggressiveness is perhaps the greatest current unmet clinical need in PC management. Largely through advances in genomic and proteomic techniques, exciting pre-clinical and clinical research is continuing to identify potential tissue, blood and urine-based PC-specific biomarkers that may in the future supplement or replace current standard practices. In this review, we describe how PC-specific biomarker research is progressing, including the evolution of PSA-based tests and those novel assays that have gained clinical approval. We also describe alternative diagnostic biomarkers to PSA, in addition to biomarkers that can predict PC aggressiveness and biomarkers that can predict response to certain therapies. We believe that novel biomarker research has the potential to make significant improvements to the clinical management of this disease in the near future.

Prostate Cancer Biomarkers: From diagnosis to prognosis and precision-guided therapeutics

Prostate cancer (PCa) is one of the most commonly diagnosed malignancies and among the leading causes of cancer-related death worldwide. It is a highly heterogeneous disease, ranging from remarkably slow progression or inertia to highly aggressive and fatal disease. As therapeutic decision-making, clinical trial design and outcome highly depend on the appropriate stratification of patients to risk groups, it is imperative to differentiate between benign versus more aggressive states. The incorporation of clinically valuable prognostic and predictive biomarkers is also potentially amenable in this process, in the timely prevention of metastatic disease and in the decision for therapy selection. This review summarizes the progress that has so far been made in the identification of the genomic events that can be used for the classification, prediction and prognostication of PCa, and as major targets for clinical intervention. We include an extensive list of emerging biomarkers for which there is enough preclinical evidence to suggest that they may constitute crucial targets for achieving significant advances in the management of the disease. Finally, we highlight the main challenges that are associated with the identification of clinically significant PCa biomarkers and recommend possible ways to overcome such limitations.

The 2019 Genitourinary Pathology Society (GUPS) White Paper on Contemporary Grading of Prostate Cancer

CONTEXT.—

Controversies and uncertainty persist in prostate cancer grading.

OBJECTIVE.—

To update grading recommendations.

DATA SOURCES.—

Critical review of the literature along with pathology and clinician surveys.

CONCLUSIONS.—

Percent Gleason pattern 4 (%GP4) is as follows: (1) report %GP4 in needle biopsy with Grade Groups (GrGp) 2 and 3, and in needle biopsy on other parts (jars) of lower grade in cases with at least 1 part showing Gleason score (GS) 4 + 4 = 8; and (2) report %GP4: less than 5% or less than 10% and 10% increments thereafter. Tertiary grade patterns are as follows: (1) replace "tertiary grade pattern" in radical prostatectomy (RP) with "minor tertiary pattern 5 (TP5)," and only use in RP with GrGp 2 or 3 with less than 5% Gleason pattern 5; and (2) minor TP5 is noted along with the GS, with the GrGp based on the GS. Global score and magnetic resonance imaging (MRI)-targeted biopsies are as follows: (1) when multiple undesignated cores are taken from a single MRI-targeted lesion, an overall grade for that lesion is given as if all the involved cores were one long core; and (2) if providing a global score, when different scores are found in the standard and the MRI-targeted biopsy, give a single global score (factoring both the systematic standard and the MRI-targeted positive cores). Grade Groups are as follows: (1) Grade Groups (GrGp) is the terminology adopted by major world organizations; and (2) retain GS 3 + 5 = 8 in GrGp 4. Cribriform carcinoma is as follows: (1) report the presence or absence of cribriform glands in biopsy and RP with Gleason pattern 4 carcinoma. Intraductal carcinoma (IDC-P) is as follows: (1) report IDC-P in biopsy and RP; (2) use criteria based on dense cribriform glands (>50% of the gland is composed of epithelium relative to luminal spaces) and/or solid nests and/or marked pleomorphism/necrosis; (3) it is not necessary to perform basal cell immunostains on biopsy and RP to identify IDC-P if the results would not change the overall (highest) GS/GrGp part per case; (4) do not include IDC-P in determining the final GS/GrGp on biopsy and/or RP; and (5) "atypical intraductal proliferation (AIP)" is preferred for an intraductal proliferation of prostatic secretory cells which shows a greater degree of architectural complexity and/or cytological atypia than typical high-grade prostatic intraepithelial neoplasia, yet falling short of the strict diagnostic threshold for IDC-P. Molecular testing is as follows: (1) Ki67 is not ready for routine clinical use; (2) additional studies of active surveillance cohorts are needed to establish the utility of PTEN in this setting; and (3) dedicated studies of RNA-based assays in active surveillance populations are needed to substantiate the utility of these expensive tests in this setting. Artificial intelligence and novel grading schema are as follows: (1) incorporating reactive stromal grade, percent GP4, minor tertiary GP5, and cribriform/intraductal carcinoma are not ready for adoption in current practice.

Assessment of MYC/PTEN Status by Gene-Protein Assay in Grade Group 2 Prostate Biopsies

This study leveraged a gene-protein assay to assess MYC and PTEN status at prostate cancer biopsy and examined the association with adverse outcomes after surgery. MYC gain and PTEN loss were simultaneously assessed by chromogenic in situ hybridization and immunohistochemistry, respectively, using 277 Grade Group 2 needle biopsies that were followed by prostatectomy. The maximal size of cribriform Gleason pattern 4 carcinoma (CRIB), the presence of intraductal carcinoma (IDC), and percentage of Gleason pattern 4 carcinoma at biopsy were also annotated. MYC gain or PTEN loss was present in 19% and 18% of biopsies, respectively, whereas both alterations were present in 9% of biopsies. Tumors with one or both alterations were significantly more likely to have non-organ-confined disease (NOCD) at radical prostatectomy. In logistic regression models, including clinical stage, tumor volume on biopsy, and presence of CRIB/IDC, cases with MYC gain and PTEN loss remained at higher risk for NOCD (odds ratio, 6.23; 95% CI, 1.74-24.55; P = 0.005). The area under the curve for a baseline model using CAPRA variables (age, prostate-specific antigen, percentage of core involvement, clinical stage) was increased from 0.68 to 0.69 with inclusion of CRIB/IDC status and to 0.75 with MYC/PTEN status. Dual MYC/PTEN status can be assessed in a single slide and is independently associated with increased risk of NOCD for Grade Group 2 biopsies.

Tissue-Based Biomarkers for the Risk Stratification of Men With Clinically Localized Prostate Cancer

Risk stratification of men with clinically localized prostate cancer has historically relied on basic clinicopathologic parameters such as prostate specific antigen level, grade group, and clinical stage. However, prostate cancer often behaves in ways that cannot be accurately predicted by these parameters. Thus, recent efforts have focused on developing tissue-based genomic tests that provide greater insights into the risk of a given patient's disease. Multiple tests are now commercially available and provide additional prognostic information at various stages of the care pathway for prostate cancer. Indeed, early evidence suggests that these assays may have a significant impact on patient and physician decision-making. However, the impact of these tests on oncologic outcomes remains less clear. In this review, we highlight recent advances in the use of tissue-based biomarkers in the treatment of prostate cancer and identify the existing evidence supporting their clinical use.

Clinical Actionability of the Genomic Landscape of Metastatic Castration Resistant Prostate Cancer

The development of targeted therapies increases treatment options for metastatic castration resistant prostate cancer (mCRPC) patients. There is a need for strong predictive and prognostic signatures to guide physicians in treating mCRPC patients. In this review we unravel the possible actionability in the AR pathway, PI3K AKT signaling, and DNA repair pathways. Additionally, we make recommendations on biomarker trial design, and the clinical use of this new type of data.

The PTEN Conundrum: How to Target PTEN-Deficient Prostate Cancer

Loss of the tumor suppressor phosphatase and tensin homologue deleted on chromosome 10 (PTEN), which negatively regulates the PI3K-AKT-mTOR pathway, is strongly linked to advanced prostate cancer progression and poor clinical outcome. Accordingly, several therapeutic approaches are currently being explored to combat PTEN-deficient tumors. These include classical inhibition of the PI3K-AKT-mTOR signaling network, as well as new approaches that restore PTEN function, or target PTEN regulation of chromosome stability, DNA damage repair and the tumor microenvironment. While targeting PTEN-deficient prostate cancer remains a clinical challenge, new advances in the field of precision medicine indicate that PTEN loss provides a valuable biomarker to stratify prostate cancer patients for treatments, which may improve overall outcome. Here, we discuss the clinical implications of PTEN loss in the management of prostate cancer and review recent therapeutic advances in targeting PTEN-deficient prostate cancer. Deepening our understanding of how PTEN loss contributes to prostate cancer growth and therapeutic resistance will inform the design of future clinical studies and precision-medicine strategies that will ultimately improve patient care.

Report From the International Society of Urological Pathology (ISUP) Consultation Conference on Molecular Pathology of Urogenital Cancers. I. Molecular Biomarkers in Prostate Cancer

The combined clinical and molecular heterogeneity of prostate cancer necessitates the use of prognostic, predictive, and diagnostic biomarkers to assist the clinician with treatment selection. The pathologist plays a critical role in guiding molecular biomarker testing in prostate cancer and requires a thorough knowledge of the current testing options. In the setting of clinically localized prostate cancer, prognostic biomarkers such as Ki-67 labeling, PTEN loss or mRNA-based genomic signatures can be useful to help determine whether definitive therapy is required. In the setting of advanced disease, predictive biomarkers, such as the presence of DNA repair deficiency mediated by BRCA2 loss or mismatch repair gene defects, may suggest the utility of poly-ADP ribosylase inhibition or immune checkpoint blockade. Finally, androgen receptor-related biomarkers or diagnostic biomarkers indicating the presence of small cell neuroendocrine prostate cancer may help guide the use of androgen receptor signaling inhibitors and chemotherapy. In this review, we examine the current evidence for several prognostic, predictive and diagnostic tissue-based molecular biomarkers in prostate cancer management. For each assay, we summarize a recent survey of the International Society of Urology Pathology (ISUP) members on current testing practices and include recommendations for testing that emerged from the ISUP Working Group on Molecular Pathology of Prostate Cancer and the 2019 Consultation Conference on Molecular Pathology of Urogenital Cancers.

Immunotherapy for Metastatic Prostate Cancer: Current and Emerging Treatment Options

The advent of immunotherapy has revolutionized cancer treatment. Prostate cancer has an immunosuppressive microenvironment and a low tumor mutation burden, resulting in low neoantigen expression. The consensus was that immunotherapy would be less effective in prostate cancer. However, recent studies have reported that prostate cancer does have a high number of DNA damage and repair gene defects. Immunotherapies that have been tested in prostate cancer so far have been mainly vaccines and checkpoint inhibitors. A combination of genomically targeted therapies, with approaches to alleviate immune response and thereby make the tumor microenvironment immunologically hot, is promising.

Design and Development of a Fully Synthetic Multiplex Ligation-Dependent Probe Amplification-Based Probe Mix for Detection of Copy Number Alterations in Prostate Cancer Formalin-Fixed, Paraffin-Embedded Tissue Samples

DNA copy number alterations (CNAs) are promising biomarkers to predict prostate cancer (PCa) outcome. However, fluorescence in situ hybridization (FISH) cannot assess complex CNA signatures because of low multiplexing capabilities. Multiplex ligation-dependent probe amplification (MLPA) can detect multiple CNAs in a single PCR assay, but PCa-specific probe mixes available commercially are lacking. Synthetic MLPA probes were designed to target 10 CNAs relevant to PCa: 5q15-21.1 (CHD1), 6q15 (MAP3K7), 8p21.2 (NKX3-1), 8q24.21 (MYC), 10q23.31 (PTEN), 12p13.1 (CDKN1B), 13q14.2 (RB1), 16p13.3 (PDPK1), 16q23.1 (GABARAPL2), and 17p13.1 (TP53), with 9 control probes. In cell lines, CNAs were detected when the cancer genome was as low as 30%. Compared with FISH in radical prostatectomy formalin-fixed, paraffin-embedded samples (n = 18: 15 cancers and 3 matched benign), the MLPA assay showed median sensitivity and specificity of 80% and 93%, respectively, across all CNAs assessed. In the validation set (n = 40: 20 tumors sampled in two areas), the respective sensitivity and specificity of MLPA compared advantageously with FISH and TaqMan droplet digital PCR (ddPCR) when assessing PTEN deletion (FISH: 85% and 100%; ddPCR: 100% and 83%) and PDPK1 gain (FISH: 100% and 92%; ddPCR: 93% and 100%). This new PCa probe mix accurately identifies CNAs by MLPA across multiple genes using low quality and quantities (50 ng) of DNA extracted from clinical formalin-fixed, paraffin-embedded samples.

Family history of prostate cancer and the incidence of ERG- and phosphatase and tensin homolog-defined prostate cancer

Family history is among the strongest known risk factors for prostate cancer (PCa). Emerging data suggest molecular subtypes of PCa, including two somatic genetic aberrations: fusions of androgen-regulated promoters with ERG and, separately, phosphatase and tensin homolog (PTEN) loss. We examined associations between family history and incidence of these subtypes in 44,126 men from the prospective Health Professionals Follow-up Study. ERG and PTEN status were assessed by immunohistochemistry. Multivariable competing risks models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations between self-reported family history of PCa and molecular subtypes of disease. Thirteen percent of men had a positive family history of PCa at baseline. During a median follow-up of 18.5 years, 5,511 PCa cases were diagnosed. Among them, 888 were assayed for ERG status (47% ERG-positive) and 715 were assayed for PTEN loss (14% PTEN null). Family history was more strongly associated with risk of ERG-negative (HR: 2.15; 95% CI: 1.71-2.70) than ERG-positive (HR: 1.49; 95% CI: 1.13-1.95) disease (p_{heterogeneity} : 0.04). The strongest difference was among men with an affected father (HR_ERG-negative : 2.09; 95% CI: 1.64-2.66; HR_ERG-positive : 1.30; 95% CI: 0.96-1.76; p_{heterogeneity} : 0.01). Family history of PCa was positively associated with both PTEN null (HR: 2.10; 95% CI: 1.26-3.49) and PTEN intact (HR: 1.72; 95% CI: 1.39-2.13) PCa (p_{heterogeneity} : 0.47). Our results indicate that PCa family history may be positively associated with PCa in all ERG and PTEN subtypes, suggesting a role of genetic susceptibility in their development. It is possible that ERG-negative disease could be especially associated with positive family history.

MicroRNAs as Theranostics Targets in Oral Carcinoma Stem Cells

Oral cancer belongs to head and neck squamous cell carcinoma and has been recognized as one of the most prevalent malignancies worldwide. Recent studies have suggested that cancer stem cells (CSCs) may participate in tumor initiation, metastasis and even recurrence, so the regulation of CSCs has drawn significant attention over the past decade. Among various molecules that are associated with CSCs, non-coding RNAs (ncRNAs) have been indicated as key players in the acquisition and maintenance of cancer stemness. In addition, accumulating studies have shown that the aberrant expression of these ncRNAs may serve as surrogate diagnostic markers or even therapeutic targets for cancer treatment. The current study reviews the previous work by us and others to summarize how these ncRNAs affect oral cancer stemness and their potential theranostic applications. A better understanding of the implication of these ncRNAs in oral tumorigenesis will facilitate the translation of basic ncRNA research into clinical application in the future.

Genetic and molecular determinants of prostate cancer among Iranian patients: An update

Prostate cancer (PCa) is one of the most common age-related cancers among men. Various environmental and genetic factors are involved in the development and progression of PCa. In most cases, the primary symptoms of disease are not severe. Therefore, it is common for patients to be referred with severe clinical manifestations at advanced stages of disease. Since this malignancy is age related and Iran will face a significant increase in the number of seniors, it is expected that the prevalence of PCa among Iranian men will rise. PCa progression has been observed to be associated with genetic and ethnic factors. It may therefore be clinically useful to determine a panel of genetic markers, in addition to routine diagnostic methods, to detect tumors in the early stages. In the present review, we have summarized the reported genetic markers in PCa Iranian patients to pave the way for the determination of an ethnic specific genetic marker panel for the early detection of PCa. To understand the genetic and molecular biology of PCa among Iranians, we have categorized these genetic markers based on their cellular functions.

Prevalence of ERG expression and PTEN loss in a Brazilian prostate cancer cohort

PTEN is the most commonly inactivated tumor suppressor gene in primary prostate cancer (PCa) and its loss is associated with poor clinical outcomes. ERG rearrangement is a genomic alteration frequently found in PCa and its prognostic significance has yielded mixed results. Although the association of PTEN and ERG biomarkers has potential impact on clinical outcomes, studies examining the two genes simultaneously are scarce in Brazilian populations. In this study, we retrospectively examined the relationship between ERG expression and PTEN loss in 119 surgically treated prostate cancer patients from Northeastern Brazil through immunohistochemical analysis. ERG expression was found in 41.0% (48/117) of cases and the loss of PTEN detected in 38.1% (40/105) of samples. ERG-positive cases were significantly associated with lower prostate weight; ERG negatively correlated with Gleason score above 6. The lack of associations for PTEN loss alone in this cohort is counter to the literature, which shows that PTEN loss is usually associated with more aggressive disease. The overlapping of the two biomarkers revealed that samples with positive ERG expression without PTEN loss were associated with lower Gleason and lower Grade group. This study contributes with the discussion about the development of the molecular profiling of prostate cancer. The further development of similar studies could help in stratifying specific risk groups, leading to a more personalized therapeutic decision for prostate cancer treatment.

Diagnostic Value of 68Ga-PSMA PET/CT for Detection of Phosphatase and Tensin Homolog Expression in Prostate Cancer: A Pilot Study

Our purpose was to explore the value of ⁶⁸Ga-prostate-specific membrane antigen (PSMA) PET/CT for detection of phosphatase and tensin homolog (PTEN)-loss prostate cancer. Methods: We retrospectively enrolled 75 patients who underwent multiparametric MRI and ⁶⁸Ga-PSMA PET/CT before radical prostatectomy. Lesions were outlined on pathologic images, and regions of interest were drawn on matched multiparametric MRI and PET/CT images. Imaging parameters, including average apparent diffusion coefficient and SUV_max, were derived. Immunohistochemical staining was performed to evaluate the PTEN status. The diagnostic performance of imaging parameters was analyzed by receiver-operating-characteristic analysis. Univariate logistic regression analyses were used to evaluate the association between clinical and imaging variables and PTEN status. Results: In total, 103 lesions from 75 patients were analyzed. Of these lesions, 38 of 103 (36.9%) showed PTEN-loss status. Our study showed a strong association between SUV_max and PTEN-loss tumors both in the per-patient analysis (P < 0.01) and in the per-lesion analysis (P < 0.01), yielding sensitivity and specificity of 0.80 and 0.77, respectively, in the per-patient analysis and 0.83 and 0.74, respectively, in the per-lesion analysis. Meanwhile, higher pathologic PSMA expression was found in the PTEN-deficiency tumors. However, there was no significant difference between PTEN-loss tumors and PTEN-intact tumors using parameters such as average apparent diffusion coefficient (P > 0.05) and score on the Prostate Imaging Reporting and Data System, version 2 (P > 0.05). Surprisingly, SUV_max was a significant predictor for detection of PTEN-loss tumors (odds ratio of 7.56 and 95% confidence interval of 2.18-26.24 on per-patient analysis; odds ratio of 13.66 and 95% confidence interval of 4.32-43.24 on per-lesion analysis). Conclusion: ⁶⁸Ga-PSMA PET/CT could effectively detect aggressive PTEN-loss tumors.

Loss of PTEN Accelerates NKX3.1 Degradation to Promote Prostate Cancer Progression

NKX3.1 is the most commonly deleted gene in prostate cancer and a gatekeeper suppressor. NKX3.1 is a growth suppressor, mediator of apoptosis, inducer of antioxidants, and enhancer of DNA repair. PTEN is a ubiquitous tumor suppressor that is often decreased in prostate cancer during tumor progression. Steady-state turnover of NKX3.1 is mediated by DYRK1B phosphorylation at NKX3.1 serine 185 that leads to polyubiquitination and proteasomal degradation. In this study, we show PTEN is an NKX3.1 phosphatase that protects NKX3.1 from degradation. PTEN specifically opposed phosphorylation at NKX3.1(S185) and prolonged NKX3.1 half-life. PTEN and NKX3.1 interacted primarily in the nucleus as loss of PTEN nuclear localization abrogated its ability to bind to and protect NKX3.1 from degradation. The effect of PTEN on NKX3.1 was mediated via rapid enzyme-substrate interaction. An effect of PTEN on Nkx3.1 gene transcription was seen in vitro, but not in vivo. In gene-targeted mice, Nkx3.1 expression significantly diminished shortly after loss of Pten expression in the prostate. Nkx3.1 loss primarily increased prostate epithelial cell proliferation in vivo. In these mice, Nkx3.1 mRNA was not affected by Pten expression. Thus, the prostate cancer suppressors PTEN and NKX3.1 interact and loss of PTEN is responsible, at least in part, for progressive loss of NKX3.1 that occurs during tumor progression. SIGNIFICANCE: PTEN functions as a phosphatase of NKX3.1, a gatekeeper suppressor of prostate cancer.

V-ATPase-associated prorenin receptor is upregulated in prostate cancer after PTEN loss

Phosphatase and tensin homolog (PTEN) tumor suppressor protein loss is common in prostate cancer (PCa). PTEN loss increases PI3K/Akt signaling, which promotes cell growth and survival. To find secreted biomarkers of PTEN loss, a proteomic screen was used to compare secretomes of cells with and without PTEN expression. We showed that PTEN downregulates Prorenin Receptor (PRR) expression and secretion of soluble Prorenin Receptor (sPRR) in PCa cells and in mouse. PRR is an accessory protein required for assembly of the vacuolar ATPase (V-ATPase) complex. V-ATPase is required for lysosomal acidification, amino acid sensing, efficient mechanistic target of Rapamycin complex 1 (mTORC1) activation, and β-Catenin signaling. On PCa tissue microarrays, PRR expression displayed a positive correlation with Akt phosphorylation. Moreover, PRR expression was required for proliferation of PCa cells by maintaining V-ATPase function. Further, we provided evidence for a potential clinical role for PRR expression and sPRR concentration in differentiating low from high Gleason grade PCa. Overall, the current study unveils a mechanism by which PTEN can inhibit tumor growth. Lower levels of PRR result in attenuated V-ATPase activity and reduced PCa cell proliferation.

Practical Molecular Testing in a Clinical Genitourinary Service

CONTEXT.—

Molecular testing is increasingly playing a key role in the diagnosis, prognosis, and treatment of neoplasms of the genitourinary system.

OBJECTIVE.—

To provide a general overview of the clinically relevant molecular tests available for neoplasms of the genitourinary tract.

DATA SOURCES.—

Relevant medical literature indexed on PubMed.

CONCLUSIONS.—

Understanding of the molecular oncology of genitourinary neoplasms is rapidly advancing, and the pathologist must be aware of the practical implications of molecular testing. While many genomic abnormalities are not yet clinically relevant, there is an increasing library of ancillary tests that may guide diagnosis, prognosis, and/or treatment of many neoplasms. Recurrent genomic abnormalities have been identified in many types of renal cell carcinoma, and some types of renal cell carcinoma are specifically defined by the molecular abnormality. Two major routes of developing urothelial carcinoma have been molecularly described. Recurrent translocations involving ETS family genes are found in approximately half of prostate cancer cases. Testicular germ cell tumors typically harbor i(12p). Penile neoplasms are often high-risk human papillomavirus-driven cancers. Nonetheless, even as genitourinary neoplasms are increasingly better understood at the molecular level, further research with eventual clinical validation is needed for optimal diagnosis, prognosis, and treatment of aggressive malignancies in the genitourinary tract.

PTEN Tumor-Suppressor: The Dam of Stemness in Cancer

PTEN is one of the most frequently inactivated tumor suppressor genes in cancer. Loss or variation in PTEN gene/protein levels is commonly observed in a broad spectrum of human cancers, while germline PTEN mutations cause inherited syndromes that lead to increased risk of tumors. PTEN restrains tumorigenesis through different mechanisms ranging from phosphatase-dependent and independent activities, subcellular localization and protein interaction, modulating a broad array of cellular functions including growth, proliferation, survival, DNA repair, and cell motility. The main target of PTEN phosphatase activity is one of the most significant cell growth and pro-survival signaling pathway in cancer: PI3K/AKT/mTOR. Several shreds of evidence shed light on the critical role of PTEN in normal and cancer stem cells (CSCs) homeostasis, with its loss fostering the CSC compartment in both solid and hematologic malignancies. CSCs are responsible for tumor propagation, metastatic spread, resistance to therapy, and relapse. Thus, understanding how alterations of PTEN levels affect CSC hallmarks could be crucial for the development of successful therapeutic approaches. Here, we discuss the most significant findings on PTEN-mediated control of CSC state. We aim to unravel the role of PTEN in the regulation of key mechanisms specific for CSCs, such as self-renewal, quiescence/cell cycle, Epithelial-to-Mesenchymal-Transition (EMT), with a particular focus on PTEN-based therapy resistance mechanisms and their exploitation for novel therapeutic approaches in cancer treatment.

Association of mTOR Pathway Markers and Clinical Outcomes in Patients with Intermediate-/High-risk Prostate Cancer: Long-Term Analysis

INTRODUCTION

The mammalian target of rapamycin (mTOR) pathway is up-regulated in prostate cancer (PCa). We evaluated the tumor tissue expression of downstream mTOR targets in patients with intermediate- and high-risk (IR/HR) PCa and their ability to predict outcome after radical prostatectomy (RP).

PATIENTS AND METHODS

Immunohistochemical (IHC) analysis using antibodies against PTEN, mTOR, p-mTOR, pAKT, pS6, and Ki-67 was performed on a tissue microarray constructed from formalin-fixed paraffin-embedded RP specimens. The marker expression was analyzed to determine their predictability for biochemical recurrence (BCR).

RESULTS

Tumor tissue from 217 patients (86 IR/131 HR) was analyzed. The most frequent markers were p-mTOR, which was expressed in most cases (85%), whereas PTEN and pS6 were detected in 53% and 40% of the cases, respectively. Overexpression of PTEN (P = .02) and pS6 (P < .001) was associated with HR features. With a median follow up of 13.5 years, 39% (77/196) of patients developed BCR after RP, more frequently (31%) in patients with HR disease (P < .001). Overexpression of pS6 (P = .036), Ki67% (P = .024), and lack of expression of mTOR (P = .021) were associated with BCR. The 5- and 10-year survival rate was 81% and 66%, respectively.

CONCLUSIONS

Protein expression of downstream mTOR molecules was significantly associated with outcome of patients with IR and HR PCa. Markers of the mTOR pathway could be incorporated in clinical studies evaluating inhibitors of the signaling pathway for treatment selection in men with PCa.

PTEN Expression in Prostate Cancer: Relationship With Clinicopathologic Features and Multiparametric MRI Findings

OBJECTIVE. The objective of our study was to investigate whether phosphatase and tensin homolog (PTEN) expression is associated with clinicopathologic features and multiparametric MRI findings in prostate cancer. MATERIALS AND METHODS. Forty-three patients with prostate cancer who underwent radical prostatectomy were included. Index tumor was identified on pretreatment MRI and delineated in the area that correlated best with histopathology results. The apparent diffusion coefficient (ADC) from DWI and pharmacokinetic parameters derived from dynamic contrast-enhanced MRI (DCE-MRI) using the extended Tofts model (K^trans, k_ep, v_e, and v_p) within the tumor were estimated. The following clinicopathologic parameters were assessed: pretreatment serum levels of prostate-specific antigen, disseminated tumor cell status, age, Gleason score, tumor size, extraprostatic extension (EPE), tumor location, and lymph node metastases. Gene expression profiles were acquired in biopsies from the tumor using bead arrays, and validated using reverse transcription quantitative polymerase chain reaction (RT-qPCR) on a different part of the biopsy. RESULTS. Based on bead arrays (p = 0.006) and RT-qPCR (p = 0.03) data, a significantly lower ADC was found in tumors with low PTEN expression. Moreover, PTEN expression was negatively associated with lymph node metastases (bead arrays, p = 0.008; RT-qPCR, p < 0.001). A weak but significant association between PTEN expression, EPE (p = 0.048), and Gleason score (p = 0.028) was revealed on bead arrays. ADC was negatively correlated with Gleason score (p = 0.001) and tumor size (p = 0.023). No association among DCE parameters, PTEN expression, and clinicopathologic features was found. CONCLUSION. ADC derived from DWI may be useful in selecting patients with potentially aggressive tumor caused by PTEN deficiency.

MicroRNAs, Hypoxia and the Stem-Like State as Contributors to Cancer Aggressiveness

MicroRNAs (miRNAs) are small non-coding RNA molecules that play key regulatory roles in cancer acting as both oncogenes and tumor suppressors. Due to their potential roles in improving cancer prognostic, predictive, diagnostic and therapeutic approaches, they have become an area of intense research focus in recent years. Several studies have demonstrated an altered expression of several miRNAs under hypoxic condition and even shown that the hypoxic microenvironment drives the selection of a more aggressive cancer cell population through cellular adaptations referred as the cancer stem-like cell. These minor fractions of cells are characterized by their self-renewal abilities and their ability to maintain the tumor mass, suggesting their crucial roles in cancer development. This review aims to highlight the interconnected role between miRNAs, hypoxia and the stem-like state in contributing to the cancer aggressiveness as opposed to their independent contributions, and it is based in four aggressive tumors, namely glioblastoma, cervical, prostate, and breast cancers.

PTEN Loss in a Prostate Cancer Cohort From Jordan

Deletion of phosphatase and tensin homolog (PTEN) in prostate cancer has been associated with early biochemical recurrence, increased metastatic potential, and androgen independence. We evaluated the status of PTEN loss in a cohort of prostate cancer patients from Jordan. We investigated 71 patients with prostate cancer and 52 control subjects with benign prostatic hyperplasia (BPH). PTEN status was assessed by immunohistochemistry. PTEN mutations on exons 1, 2, 5, and 8 were also evaluated by polymerase chain reaction single-stranded conformation polymorphism (PCR-SSCP). We found PTEN loss in 42 of 71 (59.2%) evaluated prostate cancer cases by immunohistochemistry. In contrast, 51 of 52 BPH (98.1%) cases had an intact PTEN. In a subset of 24 prostate cancer cases evaluated by PCR-SSCP, we found PTEN mutations in 15 (62.5%) cases, whereas 22 (91.7%) of BPH controls lacked PTEN mutations. Exon 5 was the most frequently mutated exon (37.5%). Although the loss of PTEN was not significantly correlated with the Gleason Score (GS) or the World Health Organization (WHO)-International Society of Urological Pathology (ISUP) Grade Group (GG), we found higher frequency of PTEN loss (64%) in patients with GS≥4+3/GG≥3, compared with patients with GS≤3+4/GG≤2 (47.6%). In this first study to address the question of PTEN loss in a predominantly Arab population, we documented the frequency of PTEN loss in prostate cancer patients from Jordan, which was found to be higher than in comparable cohorts from East Asia, and was at the higher end of the range of reported frequency of PTEN loss in respective cohorts from North America and Western Europe. Although there was more frequent PTEN loss in cancers with higher GS/GG, this was not statistically significant.

The combination of PTEN deletion and 16p13.3 gain in prostate cancer provides additional prognostic information in patients treated with radical prostatectomy

Prostate cancer is a clinically heterogeneous disease and accurately risk-stratifying patients is a key clinical challenge. We hypothesized that the concurrent identification of the DNA copy number alterations 10q23.3 (PTEN) deletion and 16p13.3 (PDPK1) gain, related to the PI3K/AKT survival pathway, would improve prognostication. We assessed PTEN deletion status using fluorescence in situ hybridization (FISH) and evaluated its clinical significance in combination with the 16p13.3 gain in a set of 332 primary radical prostatectomy cases on a tissue microarray with clinical follow-up. The PTEN deletion was detected in 34% (97/287) of the evaluable tumors and was significantly associated with high Gleason grade group (P < 0.0001) and advanced pathological tumor stage (pT-stage, P < 0.001). The PTEN deletion emerged as a significant predictor of biochemical recurrence independent of the standard clinicopathologic parameters (hazard ratio: 3.00, 95% confidence interval: 1.81-4.98; P < 0.0001) and further stratified patients with low and intermediate risk of biochemical recurrence [Gleason grade group 1-2 (≤3 + 4), Gleason grade group 2 (3 + 4), pT2, prostate-specific antigen ≤ 10, low and intermediate CAPRA-S score; log-rank P ≤ 0.007]. A PTEN deletion also increased the risk of distant metastasis (log-rank, P = 0.001), further supporting its role in prostate cancer progression. Combining both 16p13.3 gain and PTEN deletion improved biochemical recurrence risk stratification and provided prognostic information beyond the established CAPRA-S score (co-alteration: hazard ratio: 4.70, 95% confidence interval: 2.12-10.42; P < 0.0001). Our study demonstrates the potential clinical utility of PTEN genomic deletion in low-intermediate risk patients and highlights the enhanced prognostication achieved when assessed in combination with another genomic biomarker related to the PI3K/AKT pathway, thereby supporting their promising usefulness in clinical management of prostate cancer.

Association of ERG/PTEN status with biochemical recurrence after radical prostatectomy for clinically localized prostate cancer

We have previously demonstrated a significant correlative relationship between PTEN deletion and ERG rearrangement, both in the development of clinically localized prostate cancers and metastases. Herein, we evaluate the cooperative role of ERG and PTEN in oncological outcomes after radical prostatectomy for clinically localized prostate cancer. We evaluated ERG and PTEN status using three previously described cohorts. The first cohort included 235 clinically localized prostate cancer cases represented on tissue microarrays (TMA), evaluated using previously validated FISH assays for ERG and PTEN. The second cohort included 167 cases of clinically localized prostate cancer on TMAs evaluated for PTEN by FISH, and for PTEN and ERG by dual IHC. The third cohort comprised 59 clinically localized prostate cancer cases assessed by array comparative genomic hybridization (aCGH). Kaplan-Meir plots and long rank tests were used to assess the association of ERG and PTEN status with biochemical recurrence after radical prostatectomy for clinically localized prostate cancer. Of the 317 cases eligible for analyses with evaluable ERG and PTEN status, 88 (27.8%) patients developed biochemical recurrence over a median follow-up of 5.7 years. Overall, 45% (142/317) of cases demonstrated ERG rearrangement and 20% (62/317) of cases demonstrated PTEN loss. Hemizygous and homozygous deletion of PTEN was seen in 10% (18/175) and 3% (5/175) of ERG-negative cases, respectively. In contrast, hemizygous and homozygous deletion of PTEN was seen in 11% (15/142) and 17% (24/123) of ERG-positive cases, respectively. PTEN loss (heterozygous or homozygous) was significantly associated with shorter time to biochemical recurrence compared to no PTEN loss (p < 0.001). However, ERG rearrangement versus no rearrangement was not associated with time to PSA recurrence (p = 0.15). Patients who exhibited ERG rearrangement and loss of PTEN had no significant difference in time to recurrence compared to patients with wild-type ERG and loss of PTEN (p = 0.30). Our findings confirm a mutual cooperative role of ERG and PTEN in the pathogenesis of prostate cancer, particularly for homozygous PTEN deletion. ERG did not stratify outcome either alone or in combination with PTEN in this cohort.

Restoration of tumour-growth suppression in vivo via systemic nanoparticle-mediated delivery of PTEN mRNA

PTEN is a well-characterized tumour-suppressor gene that is lost or mutated in about half of metastatic castration-resistant prostate cancers and in many other human cancers. The restoration of functional PTEN as a treatment for prostate cancer has however proven difficult. Here, we show that PTEN mRNA can be reintroduced into PTEN-null prostate cancer cells in vitro and in vivo via its encapsulation in polymer-lipid hybrid nanoparticles coated with a poly(ethylene glycol) shell. The nanoparticles are stable in serum, elicit low toxicity, enable high PTEN mRNA transfection in prostate cancer cells, and lead to significant inhibition of tumour growth when delivered systemically in multiple mouse models of prostate cancer. We also show that the restoration of PTEN function in PTEN-null prostate cancer cells inhibits the PI3K-AKT pathway and enhances apoptosis. Our findings provide proof-of-principle evidence of the restoration of mRNA-based tumour suppression in vivo.

Genome-Based Classification and Therapy of Prostate Cancer

In the past decade, multi-national and multi-center efforts were launched to sequence prostate cancer genomes, transcriptomes, and epigenomes with the aim of discovering the molecular underpinnings of tumorigenesis, cancer progression, and therapy resistance. Multiple biological markers and pathways have been discovered to be tumor drivers, and a molecular classification of prostate cancer is emerging. Here, we highlight crucial findings of these genome-sequencing projects in localized and advanced disease. We recapitulate the utility and limitations of current clinical practices to diagnosis, prognosis, and therapy, and we provide examples of insights generated by the molecular profiling of tumors. Novel treatment concepts based on these molecular alterations are currently being addressed in clinical trials and will lead to an enhanced implementation of precision medicine strategies.

Characterization of novel cell lines derived from a MYC-driven murine model of lethal metastatic adenocarcinoma of the prostate

BACKGROUND

Loss or mutation of PTEN alleles at 10q23 in combination with 8q24 amplification (encompassing MYC) are common findings in aggressive, human prostate cancer. Our group recently developed a transgenic murine model of prostate cancer involving prostate-specific Pten deletion and forced expression of MYC under the control of the Hoxb13 promoter. MYC overexpression cooperated with Pten loss to recapitulate lethal, human prostate cancer.

METHOD

We now report on the generation of two mouse prostate cancer cell lines, BMPC1 and BMPC2, derived from a lymph node, and liver metastasis, respectively.

RESULTS

Both cell lines demonstrate a phenotype consistent with adenocarcinoma and grew under standard tissue culture conditions. Androgen receptor (AR) protein expression is minimal (BMPC1) or absent (BMPC2) consistent with AR loss observed in the BMPC mouse model of invasive adenocarcinoma. Growth in media containing charcoal-stripped serum resulted in an increase in AR mRNA in BMPC1 cells with no effect on protein expression, unless androgens were added, in which case AR protein was stabilized, and showed nuclear localization. AR expression in BMPC2 cells was not effected by growth media or treatment with androgens. Treatment with an anti-androgen/castration or androgen supplemented media did not affect in vitro or in vivo growth of either cell line, irrespective of nuclear AR detection.

DISCUSSION

These cell lines are a novel model of androgen-insensitive prostatic adenocarcinoma driven by MYC over-expression and Pten loss.

PTEN deficiency confers colorectal cancer cell resistance to dual inhibitors of FLT3 and aurora kinase A

PTEN is a tumor suppressor found mutated in many cancers. From a synthetic lethality drug screen with PTEN-isogenic colorectal cancer cells, we found that mutant-PTEN cells were resistant to dual inhibitors of FLT3 and aurora kinase-A, including KW2449 and ENMD-2076. KW2449 significantly reduced the viability of wildtype-PTEN cells causing apoptosis, while little effect was observed in mutant-PTEN counterparts. Transcriptome profiling showed that members of PI3K-AKT signaling pathway were strongly changed in cells after KW2449 treatment, indicating a potential role of the pathway in drug resistance. We found that KW2449 caused a dose-dependent, biphasic induction of AKT phosphorylation at Ser473 in mutant-PTEN cells. Co-treatment with the inhibitors of its upstream signaling completely abolished the reactivation of AKT phosphorylation by KW2449 and reversed the drug resistant phenotype. These data suggest that reactivation of AKT phosphorylation at Ser473 is a key factor to confer drug resistant phenotype of mutant-PTEN cells to the dual inhibitors and that proper drug combinations that shut down AKT reactivation is necessary for the effective treatment of mutant-PTEN cancer with the dual inhibitors in clinical settings.

Genomic Deletion at 10q23 in Prostate Cancer: More Than PTEN Loss?

The PTEN gene encodes for the phosphatase and tensin homolog; it is a tumor suppressor gene that is among the most frequently inactivated genes throughout the human cancer spectrum. The most recent sequencing approaches have allowed the identification of PTEN genomic alterations, including deletion, mutation, or rearrangement in about 50% of prostate cancer (PCa) cases. It appears that mechanisms leading to PTEN inactivation are cancer-specific, comprising gene mutations, small insertions/deletions, copy number alterations (CNAs), promoter hypermethylation, and RNA interference. The examination of publicly available results from deep-sequencing studies of various cancers showed that PCa appears to be the only cancer in which PTEN is lost mostly through CNA. Instead of inactivating mutations, which are seen in other cancers, deletion of the 10q23 locus is the most common form of PTEN inactivation in PCa. By investigating the minimal deleted region at 10q23, several other genes appear to be lost simultaneously with PTEN. Expression data indicate that, like PTEN, these genes are also downregulated upon loss of 10q23. These analyses raise the possibility that 10q23 is lost upon selective pressure not only to inactivate PTEN but also to impair the expression of surrounding genes. As such, several genes from this deleted region, which represents about 500 kb, may also act as tumor suppressors in PCa, requiring further studies on their respective functions in that context.

MAGI2 is an independent predictor of biochemical recurrence in prostate cancer

BACKGROUND

Membrane-associated guanylate kinase, WW and PDZ domain-containing protein 2 (MAGI2) promotes the activity of phosphatase and tensin homolog (PTEN). Recent studies suggest that dysregulation of this signaling pathway has a role in prostate carcinogenesis. Our study aims to determine the prognostic significance of MAGI2 expression in prostate cancer.

METHODS

Tissue microarrays from 51 radical prostatectomy cases including benign prostatic tissue, high grade prostatic intraepithelial neoplasia (HGPIN), and adenocarcinoma were constructed. Immunohistochemistry with double staining for MAGI2 and p63 was performed and analyzed by image analysis as percent of analyzed area (%AREA). Multivariable logistic regression was used to correlate MAGI2 expression with clinical outcomes. Generalized Estimating Equations (GEE) with linear and logistic regression was used to correlate MAGI2 with intrapatient histology.

RESULTS

MAGI2 %AREA was inversely associated with progression from HGPIN to adenocarcinoma of low to high Gleason score (OR, 0.980; slope, -0.02; P = 0.005) and HGPIN to cancer of any Gleason score (OR, 0.969; P = 0.007). After adjusting for grade, stage, and margin status, MAGI2 %AREA was a significant independent predictor of biochemical recurrence (BCR) (OR, 0.936; 95%CI, 0.880-0.996; P = 0.037; bootstrap P = 0.017). The addition of MAGI2 %AREA to these standard clinical parameters improved accuracy of predicting BCR by 2.9% (91.0% vs 88.1%).

CONCLUSIONS

These results reveal that MAGI2 expression is reduced during prostate cancer progression and that retention of MAGI2 signal reduces odds of BCR. The study results further suggest a possible role of MAGI2 in prostate neoplasia. Decreased MAGI2 expression may help predict prostate cancer aggressiveness and provide new insight for treatment decisions and post-operative surveillance intervals.