Clinical implications of PTEN loss in prostate cancer

Risk Stratification of Prostate Cancer Through Quantitative Assessment of PTEN Loss (qPTEN)

BACKGROUND

Phosphatase and tensin homolog (PTEN) loss has long been associated with adverse findings in early prostate cancer. Studies to date have yet to employ quantitative methods (qPTEN) for measuring of prognostically relevant amounts of PTEN loss in postsurgical settings and demonstrate its clinical application.

METHODS

PTEN protein levels were measured by immunohistochemistry in radical prostatectomy samples from training (n = 410) and validation (n = 272) cohorts. PTEN loss was quantified per cancer cell and per tissue microarray core. Thresholds for identifying clinically relevant PTEN loss were determined using log-rank statistics in the training cohort. Univariate (Kaplan-Meier) and multivariate (Cox proportional hazards) analyses on various subpopulations were performed to assess biochemical recurrence-free survival (BRFS) and were independently validated. All statistical tests were two-sided.

RESULTS

PTEN loss in more than 65% cancer cells was most clinically relevant and had statistically significant association with reduced BRFS in training (hazard ratio [HR] = 2.48, 95% confidence interval [CI] = 1.59 to 3.87; P < .001) and validation cohorts (HR = 4.22, 95% CI = 2.01 to 8.83; P < .001). The qPTEN scoring method identified patients who recurred within 5.4 years after surgery (P < .001). In men with favorable risk of biochemical recurrence (Cancer of the Prostate Risk Assessment - Postsurgical scores <5 and no adverse pathological features), qPTEN identified a subset of patients with shorter BRFS (HR = 5.52, 95% CI = 2.36 to 12.90; P < .001) who may be considered for intensified monitoring and/or adjuvant therapy.

CONCLUSIONS

Compared with previous qualitative approaches, qPTEN improves risk stratification of postradical prostatectomy patients and may be considered as a complementary tool to guide disease management after surgery.

Immune Checkpoint Inhibitors in Prostate Cancer

Simple Summary

Metastatic prostate cancer is an incurable disease with limited treatment options. Immunotherapy has demonstrated significant success in multiple cancer types but efforts to harness its benefit in prostate cancer have so far largely been unsuccessful. In this review, we analyze the preclinical rationale for the use of immunotherapy and underlying barriers preventing responses to it. We summarize clinical studies evaluating checkpoint inhibitors in prostate cancer. In the end, we review ongoing trials exploring combination immune checkpoint inhibitors in combination with other agents with the intent to modulate the immune system to improve treatment outcomes.

Abstract

Metastatic prostate cancer is a lethal disease with limited treatment options. Immune checkpoint inhibitors have dramatically changed the treatment landscape of multiple cancer types but have met with limited success in prostate cancer. In this review, we discuss the preclinical studies providing the rationale for the use of immunotherapy in prostate cancer and underlying biological barriers inhibiting their activity. We discuss the predictors of response to immunotherapy in prostate cancer. We summarize studies evaluating immune checkpoint inhibitors either as a single agent or in combination with other checkpoint inhibitors or with other agents such as inhibitors of androgen axis, poly ADP-ribose polymerase (PARP), radium-223, radiotherapy, cryotherapy, tumor vaccines, chemotherapy, tyrosine kinase inhibitors, and granulocyte-macrophage colony-stimulating factor. We thereafter review future directions including the combination of immune checkpoint blockade with inhibitors of adenosine axis, bispecific T cell engagers, PSMA directed therapies, adoptive T-cell therapy, and multiple other miscellaneous agents.

The role of microRNA-572 in the proliferation and chemotherapeutic treatment of prostate cancer

OBJECTIVE

MicroRNAs (miRNAs) regulate prostate tumorigenesis and progression by involving different molecular pathways. In this study, we examined the role of miR-572 in prostate cancer (PCa).

METHODS

The proliferation rates of LNCaP and PC-3 PCa cells were studied using MTT assays. Transwell migration and Matrigel invasion assays were performed to evaluate cell migration and invasion, respectively. Protein expression levels were examined using western blotting. Docetaxel-induced apoptosis was evaluated by Caspase-Glo3/7 assays. The putative miR-572 binding site in the phosphatase and tensin homolog (PTEN) 3' untranslated region (3' UTR) was assessed with dual-luciferase reporter assays. Additionally, miR-572 expression levels in human PCa tissues were examined by qRT-PCR assays.

RESULTS

Upregulation of miR-572 promoted proliferation, migration, and invasion of PCa cells. Overexpression of miR-572 decreased sensitivity of PCa cells to docetaxel treatment by reducing docetaxel-induced apoptosis. MiR-572 can regulate migration and invasion in PCa cells. Furthermore, miR-572 could regulate expression of PTEN and p-AKT in PCa cells by directly binding to the PTEN 3' UTR. MiR-572 expression levels were increased in human PCa tissues and associated with PCa stage.

CONCLUSIONS

miR-572 displayed essential roles in PCa tumor growth and its expression level may be used to predict docetaxel treatment in these tumors.

PI3K/AKT/mTOR signalling pathway involvement in renal cell carcinoma pathogenesis (Review)

Renal cell carcinoma (RCC) accounts for over 90% of all renal malignancies, and mainly affects the male population. Obesity and smoking are involved in the pathogenesis of several systemic cancers including RCC. The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signalling pathway regulates cell growth, differentiation, migration, survival, angiogenesis, and metabolism. Growth factors, hormones, cytokine and many extracellular cues activate PI3K/AKT/mTOR. Dysregulation of this molecular pathway is frequently reported in human cancers including RCC and is associated with aggressive development and poor survival rate. mTOR is the master regulator of cell metabolism and growth, and is activated in many pathological processes such as tumour formation, insulin resistance and angiogenesis. mTOR inhibitors are used at present as drug therapy for RCC to inhibit cell proliferation, growth, survival, and the cell cycle. Temsirolimus and everolimus are two mTOR inhibitors that are currently used for the treatment of RCC. Drugs targeting the PI3K/AKT/mTOR signalling pathway may be one of the best therapeutic options for RCC.

Biomarkers for prostate cancer: prostate-specific antigen and beyond

In recent years, several new biomarkers supplementing the role of prostate-specific antigen (PSA) have become available for men with prostate cancer. Although widely used in an ad hoc manner, the role of PSA in screening asymptomatic men for prostate cancer is controversial. Several expert panels, however, have recently recommended limited PSA screening following informed consent in average-risk men, aged 55-69 years. As a screening test for prostate cancer however, PSA has limited specificity and leads to overdiagnosis which in turn results in overtreatment. To increase specificity and reduce the number of unnecessary biopsies, biomarkers such as percent free PSA, prostate health index (PHI) or the 4K score may be used, while Progensa PCA3 may be measured to reduce the number of repeat biopsies in men with a previously negative biopsy. In addition to its role in screening, PSA is also widely used in the management of patients with diagnosed prostate cancer such as in surveillance following diagnosis, monitoring response to therapy and in combination with both clinical and histological criteria in risk stratification for recurrence. For determining aggressiveness and predicting outcome, especially in low- or intermediate-risk men, tissue-based multigene tests such as Decipher, Oncotype DX (Prostate), Prolaris and ProMark, may be used. Emerging therapy predictive biomarkers include AR-V7 for predicting lack of response to specific anti-androgens (enzalutamide, abiraterone), BRAC1/2 mutations for predicting benefit from PARP inhibitor and PORTOS for predicting benefit from radiotherapy. With the increased availability of multiple biomarkers, personalised treatment for men with prostate cancer is finally on the horizon.

The Influence of Anti-Diabetic Drugs on Prostate Cancer

The incidences of prostate cancer (PC) and diabetes are increasing, with a sustained trend. The occurrence of PC and type 2 diabetes mellitus (T2DM) is growing with aging. The correlation between PC occurrence and diabetes is noteworthy, as T2DM is correlated with a reduced risk of incidence of prostate cancer. Despite this reduction, diabetes mellitus increases the mortality in many cancer types, including prostate cancer. The treatment of T2DM is based on lifestyle changes and pharmacological management. Current available drugs, except insulin, are aimed at increasing insulin secretion (sulfonylureas, incretin drugs), improving insulin sensitivity (biguanides, thiazolidinediones), or increasing urinary glucose excretion (gliflozin). Comorbidities should be taken into consideration during the treatment of T2DM. This review describes currently known information about the mechanism and impact of commonly used antidiabetic drugs on the incidence and progression of PC. Outcomes of pre-clinical studies are briefly presented and their correlations with available clinical trials have also been observed. Available reports and meta-analyses demonstrate that most anti-diabetic drugs do not increase the risk during the treatment of patients with PC. However, some reports show a potential advantage of treatment of T2DM with specific drugs. Based on clinical reports, use of metformin should be considered as a therapeutic option. Moreover, anticancer properties of metformin were augmented while combined with GLP-1 analogs.

Optimizing the diagnosis and management of ductal prostate cancer

Ductal adenocarcinoma (DAC) is the most common variant histological subtype of prostate carcinoma and has an aggressive clinical course. DAC is usually characterized and treated as high-risk prostatic acinar adenocarcinoma (PAC). However, DAC has a different biology to that of acinar disease, which often poses a challenge for both diagnosis and management. DAC can be difficult to identify using conventional diagnostic modalities such as serum PSA levels and multiparametric MRI, and the optimal management for localized DAC is unknown owing to the rarity of the disease. Following definitive therapy for localized disease with radical prostatectomy or radiotherapy, the majority of DACs recur with visceral metastases at low PSA levels. Various systemic therapies that have been shown to be effective in high-risk PAC have limited use in treating DAC. Although current understanding of the biology of DAC is limited, genomic analyses have provided insights into the pathology behind its aggressive behaviour and potential future therapeutic targets.

Radiomic and Genomic Machine Learning Method Performance for Prostate Cancer Diagnosis: Systematic Literature Review

BACKGROUND

Machine learning algorithms have been drawing attention at the joining of pathology and radiology in prostate cancer research. However, due to their algorithmic learning complexity and the variability of their architecture, there is an ongoing need to analyze their performance.

OBJECTIVE

This study assesses the source of heterogeneity and the performance of machine learning applied to radiomic, genomic, and clinical biomarkers for the diagnosis of prostate cancer. One research focus of this study was on clearly identifying problems and issues related to the implementation of machine learning in clinical studies.

METHODS

Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) protocol, 816 titles were identified from the PubMed, Scopus, and OvidSP databases. Studies that used machine learning to detect prostate cancer and provided performance measures were included in our analysis. The quality of the eligible studies was assessed using the QUADAS-2 (quality assessment of diagnostic accuracy studies-version 2) tool. The hierarchical multivariate model was applied to the pooled data in a meta-analysis. To investigate the heterogeneity among studies, I2 statistics were performed along with visual evaluation of coupled forest plots. Due to the internal heterogeneity among machine learning algorithms, subgroup analysis was carried out to investigate the diagnostic capability of machine learning systems in clinical practice.

RESULTS

In the final analysis, 37 studies were included, of which 29 entered the meta-analysis pooling. The analysis of machine learning methods to detect prostate cancer reveals the limited usage of the methods and the lack of standards that hinder the implementation of machine learning in clinical applications.

CONCLUSIONS

The performance of machine learning for diagnosis of prostate cancer was considered satisfactory for several studies investigating the multiparametric magnetic resonance imaging and urine biomarkers; however, given the limitations indicated in our study, further studies are warranted to extend the potential use of machine learning to clinical settings. Recommendations on the use of machine learning techniques were also provided to help researchers to design robust studies to facilitate evidence generation from the use of radiomic and genomic biomarkers.

TUBB3 is associated with PTEN, neuroendocrine differentiation, and castration resistance in prostate cancer

BACKGROUND

Tubulin-β3 encoded by the Tubulin-β3 (TUBB3) gene is a microtubule protein. Previous studies have shown that TUBB3 expression is upregulated in castration-resistant prostate cancer (CaP) and is involved in taxane resistance. However, the biological mechanism of TUBB3 involvement in the progression to castration-resistant CaP is not fully elucidated. This study aimed to analyze the expression and function of TUBB3 in localized and metastatic CaP.

METHODS

TUBB3 expression was determined using immunohistochemistry in localized and metastatic CaP. We also investigated the association between TUBB3, phosphatase and tensin homolog (PTEN), and neuroendocrine differentiation and examined the involvement of TUBB3 in new antiandrogen drugs (enzalutamide and apalutamide) resistance in metastatic CaP.

RESULTS

In 155 cases of localized CaP, immunohistochemistry showed that 5 (3.2%) of the CaP cases were positive for tubulin-β3. Kaplan-Meier analysis showed that high expression of tubulin-β3 was associated with poor prostate-specific antigen recurrence-free survival after radical prostatectomy. In 57 cases of metastatic CaP, immunohistochemistry showed that 14 (25%) cases were positive for tubulin-β3. Tubulin-β3 expression was higher in metastatic CaP than in localized CaP. High tubulin-β3 expression was correlated with negative PTEN expression. TUBB3 expression was increased in neuroendocrine CaP based on several public databases. PTEN knockout decreased the sensitivity to enzalutamide and apalutamide in 22Rv-1 cells. TUBB3 knockdown reversed the sensitivity to enzalutamide and apalutamide in PTEN-CRISPR 22Rv-1 cells. High expression of tubulin-β3 and negative expression of PTEN were significantly associated with poor overall survival in metastatic CaP treated with androgen deprivation therapy.

CONCLUSIONS

These results suggest that TUBB3 may be a useful predictive biomarker for survival and play an essential role in antiandrogen resistance in CaP.

The helix-loop-helix transcriptional regulator Id4 is required for terminal differentiation of luminal epithelial cells in the prostate

Inhibitor of differentiation 4 (Id4), a member of the helix-loop-helix family of transcriptional regulators has emerged as a tumor suppressor in prostate cancer. In this study we investigated the effect of loss of Id4 (Id4-/-) on mouse prostate development. Histological analysis was performed on prostates from 25 days, 3 months and 6 months old Id4-/- mice. Expression of Amacr, Ck8, Ck18, Fkbp51, Fkbp52, androgen receptor, Pten, sca-1 and Nkx3.1 was investigated by immunohistochemistry. Results were compared to the prostates from Nkx3.1-/- mice. Id4-/- mice had smaller prostates with fewer and smaller tubules. Subtle PIN like lesions were observed at 6mo. Decreased Nkx3.1 and Pten and increased stem cell marker sca-1, PIN marker Amacr and basal cell marker p63 was observed at all ages. Persistent Ck8 and Ck18 expression suggested that loss of Id4 results in epithelial commitment but not terminal differentiation in spite of active Ar. Loss of Id4 attenuates normal prostate development and promotes hyperplasia/ dysplasia with PIN like lesions. The results suggest that loss of Id4 maintains stem cell phenotype of "luminal committed basal cells", identifying a unique prostate developmental pathway regulated by Id4.

The main anthocyanin monomer of Lycium ruthenicum Murray induces apoptosis through the ROS/PTEN/PI3K/Akt/caspase 3 signaling pathway in prostate cancer DU-145 cells

Anthocyanins have been reported to have effective chemopreventive activity. Lycium ruthenicum Murray is rich in anthocyanins and exhibits many biological activities. The purpose of this study was to investigate the effects and possible biological mechanism of the main anthocyanin monomer (Pt3G) of Lycium ruthenicum Murray on prostate cancer DU-145 cells. The cell proliferation was detected by methyl thiazolyl tetrazolium assay. The cell apoptosis rates were assessed by flow cytometric analysis and TUNEL assay. The expressions of apoptosis related proteins were evaluated by western blotting. Our data demonstrated that Pt3G inhibited cell proliferation, induced apoptosis and promoted cell cycle arrest at the S phase in a concentration-dependent manner (0, 100, 200 and 400 μg mL^-1). Furthermore, it was shown that Pt3G decreased the mitochondrial membrane permeability through regulating the expressions of Bax and Bcl-2. Western blot analysis indicated that Pt3G significantly increased the expression of PTEN and then activated the PI3K/Akt-mediated caspase 3 pathway. In addition, our results also suggested that Pt3G activated the PTEN gene to induce the apoptosis of DU-145 cells by stimulating the overproduction of ROS. To sum up, these results indicate that Pt3G inhibits cell proliferation and induces apoptosis through the ROS/PTEN/PI3K/Akt/caspase 3 signaling pathway in prostate cancer DU-145 cells. Therefore, Pt3G of Lycium ruthenicum Murray may be a potential anti-proliferative agent for the prevention or treatment of prostate cancer.

Non-Coding RNAs Set a New Phenotypic Frontier in Prostate Cancer Metastasis and Resistance

Prostate cancer (PCa) mortality remains a significant public health problem, as advanced disease has poor survivability due to the development of resistance in response to both standard and novel therapeutic interventions. Therapeutic resistance is a multifaceted problem involving the interplay of a number of biological mechanisms including genetic, signaling, and phenotypic alterations, compounded by the contributions of a tumor microenvironment that supports tumor growth, invasiveness, and metastasis. The androgen receptor (AR) is a primary regulator of prostate cell growth, response and maintenance, and the target of most standard PCa therapies designed to inhibit AR from interacting with androgens, its native ligands. As such, AR remains the main driver of therapeutic response in patients with metastatic castration-resistant prostate cancer (mCRPC). While androgen deprivation therapy (ADT), in combination with microtubule-targeting taxane chemotherapy, offers survival benefits in patients with mCRPC, therapeutic resistance invariably develops, leading to lethal disease. Understanding the mechanisms underlying resistance is critical to improving therapeutic outcomes and also to the development of biomarker signatures of predictive value. The interconversions between epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) navigate the prostate tumor therapeutic response, and provide a novel targeting platform in overcoming therapeutic resistance. Both microRNA (miRNA)- and long non-coding RNA (lncRNA)-mediated mechanisms have been associated with epigenetic changes in prostate cancer. This review discusses the current evidence-based knowledge of the role of the phenotypic transitions and novel molecular determinants (non-coding RNAs) as contributors to the emergence of therapeutic resistance and metastasis and their integrated predictive value in prostate cancer progression to advanced disease.

ERG orchestrates chromatin interactions to drive prostate cell fate reprogramming

Although cancer is commonly perceived as a disease of dedifferentiation, the hallmark of early-stage prostate cancer is paradoxically the loss of more plastic basal cells and the abnormal proliferation of more differentiated secretory luminal cells. However, the mechanism of prostate cancer proluminal differentiation is largely unknown. Through integrating analysis of the transcription factors (TFs) from 806 human prostate cancers, we found that ERG was highly correlated with prostate cancer luminal subtyping. ERG overexpression in luminal epithelial cells inhibited those cells' normal plasticity to transdifferentiate into a basal lineage, and ERG superseded PTEN loss, which favored basal differentiation. ERG KO disrupted prostate cell luminal differentiation, whereas AR KO had no such effects. Trp63 is a known master regulator of the prostate basal lineage. Through analysis of 3D chromatin architecture, we found that ERG bound and inhibited the enhancer activity and chromatin looping of a Trp63 distal enhancer, thereby silencing its gene expression. Specific deletion of the distal ERG binding site resulted in the loss of ERG-mediated inhibition of basal differentiation. Thus, ERG, in its fundamental role in lineage differentiation in prostate cancer initiation, orchestrated chromatin interactions and regulated prostate cell lineage toward a proluminal program.

Targeting the BAF complex in advanced prostate cancer

INTRODUCTION

The BRG1/BRM associated factors (BAF) complex is a chromatin remodeling SWI/SNF which is mutated in 20% of cancers. This complex has many interchangeable subunits which may have oncogenic or tumor suppressor activity in a context-dependent manner. The BAF complex is mutated in 35-50% of metastatic prostate cancer (PC); however, its role in advanced disease is unclear. This review attempts to consolidate current knowledge of the BAF complex in PC and explore potential therapeutic approaches.

AREAS COVERED

This review covers the known roles of some BAF subunits, their alterations, and the models which best explain their mechanisms in driving PC. Following this, the authors provide their expert perspective on how this complex could be targeted in the future with a personalized medicine approach.

EXPERT OPINION

Personalized medicine would allow for patient stratification to exploit synthetic lethal strategies in targeting a mutated BAF complex as shown experimentally in other cancers. BAF dependency can also be targeted in patients stratified for other molecular markers such as BRG1 targeting in phosphatase and tensin homolog (PTEN) deficient PC.

High throughput assessment of biomarkers in tissue microarrays using artificial intelligence: PTEN loss as a proof-of-principle in multi-center prostate cancer cohorts

Phosphatase and tensin homolog (PTEN) loss is associated with adverse outcomes in prostate cancer and has clinical potential as a prognostic biomarker. The objective of this work was to develop an artificial intelligence (AI) system for automated detection and localization of PTEN loss on immunohistochemically (IHC) stained sections. PTEN loss was assessed using IHC in two prostate tissue microarrays (TMA) (internal cohort, n = 272 and external cohort, n = 129 patients). TMA cores were visually scored for PTEN loss by pathologists and, if present, spatially annotated. Cores from each patient within the internal TMA cohort were split into 90% cross-validation (N = 2048) and 10% hold-out testing (N = 224) sets. ResNet-101 architecture was used to train core-based classification using a multi-resolution ensemble approach (×5, ×10, and ×20). For spatial annotations, single resolution pixel-based classification was trained from patches extracted at ×20 resolution, interpolated to ×40 resolution, and applied in a sliding-window fashion. A final AI-based prediction model was created from combining multi-resolution and pixel-based models. Performance was evaluated in 428 cores of external cohort. From both cohorts, a total of 2700 cores were studied, with a frequency of PTEN loss of 14.5% in internal (180/1239) and external 13.5% (43/319) cancer cores. The final AI-based prediction of PTEN status demonstrated 98.1% accuracy (95.0% sensitivity, 98.4% specificity; median dice score = 0.811) in internal cohort cross-validation set and 99.1% accuracy (100% sensitivity, 99.0% specificity; median dice score = 0.804) in internal cohort test set. Overall core-based classification in the external cohort was significantly improved in the external cohort (area under the curve = 0.964, 90.6% sensitivity, 95.7% specificity) when further trained (fine-tuned) using 15% of cohort data (19/124 patients). These results demonstrate a robust and fully automated method for detection and localization of PTEN loss in prostate cancer tissue samples. AI-based algorithms have potential to streamline sample assessment in research and clinical laboratories.

An acetyl-histone vulnerability in PI3K/AKT inhibition-resistant cancers is targetable by both BET and HDAC inhibitors

Acquisition of resistance to phosphatidylinositol 3-kinase (PI3K)/AKT-targeted monotherapy implies the existence of common resistance mechanisms independent of cancer type. Here, we demonstrate that PI3K/AKT inhibitors cause glycolytic crisis, acetyl-coenzyme A (CoA) shortage, and a global decrease in histone acetylation. In addition, PI3K/AKT inhibitors induce drug resistance by selectively augmenting histone H3 lysine 27 acetylation (H3K27ac) and binding of CBP/p300 and BRD4 proteins at a subset of growth factor and receptor (GF/R) gene loci. BRD4 occupation at these loci and drug-resistant cell growth are vulnerable to both bromodomain and histone deacetylase (HDAC) inhibitors. Little or no occupation of HDAC proteins at the GF/R gene loci underscores the paradox that cells respond equivalently to the two classes of inhibitors with opposite modes of action. Targeting this unique acetyl-histone-related vulnerability offers two clinically viable strategies to overcome PI3K/AKT inhibitor resistance in different cancers.

Genomic and phenotypic heterogeneity in prostate cancer

From a clinical, morphological and molecular perspective, prostate cancer is a heterogeneous disease. Primary prostate cancers are often multifocal, having topographically and morphologically distinct tumour foci. Sequencing studies have revealed that individual tumour foci can arise as clonally distinct lesions with no shared driver gene alterations. This finding demonstrates that multiple genomically and phenotypically distinct primary prostate cancers can be present in an individual patient. Lethal metastatic prostate cancer seems to arise from a single clone in the primary tumour but can exhibit subclonal heterogeneity at the genomic, epigenetic and phenotypic levels. Collectively, this complex heterogeneous constellation of molecular alterations poses obstacles for the diagnosis and treatment of prostate cancer. However, advances in our understanding of intra-tumoural heterogeneity and the development of novel technologies will allow us to navigate these challenges, refine approaches for translational research and ultimately improve patient care.

The CDCP1 Signaling Hub: A Target for Cancer Detection and Therapeutic Intervention

CUB-domain containing protein 1 (CDCP1) is a type I transmembrane glycoprotein that is upregulated in malignancies of the breast, lung, colorectum, ovary, kidney, liver, pancreas, and hematopoietic system. Here, we discuss CDCP1 as an important hub for oncogenic signaling and its key roles in malignant transformation and summarize approaches focused on exploiting it for cancer diagnosis and therapy. Elevated levels of CDCP1 are associated with progressive disease and markedly poorer survival. Predominantly located on the cell surface, CDCP1 lies at the nexus of key tumorigenic and metastatic signaling cascades, including the SRC/PKCδ, PI3K/AKT, WNT, and RAS/ERK axes, the oxidative pentose phosphate pathway, and fatty acid oxidation, making important functional contributions to cancer cell survival and growth, metastasis, and treatment resistance. These findings have stimulated the development of agents that target CDCP1 for detection and treatment of a range of cancers, and results from preclinical models suggest that these approaches could be efficacious and have manageable toxicity profiles.

Therapeutic Implications of TGFβ in Cancer Treatment: A Systematic Review

Transforming growth factor β (TGFβ) is a pleiotropic cytokine that participates in a wide range of biological functions. The alterations in the expression levels of this factor, or the deregulation of its signaling cascade, can lead to different pathologies, including cancer. A great variety of therapeutic strategies targeting TGFβ, or the members included in its signaling pathway, are currently being researched in cancer treatment. However, the dual role of TGFβ, as a tumor suppressor or a tumor-promoter, together with its crosstalk with other signaling pathways, has hampered the development of safe and effective treatments aimed at halting the cancer progression. This systematic literature review aims to provide insight into the different approaches available to regulate TGFβ and/or the molecules involved in its synthesis, activation, or signaling, as a cancer treatment. The therapeutic strategies most commonly investigated include antisense oligonucleotides, which prevent TGFβ synthesis, to molecules that block the interaction between TGFβ and its signaling receptors, together with inhibitors of the TGFβ signaling cascade-effectors. The effectiveness and possible complications of the different potential therapies available are also discussed.

Tumour suppression through modulation of neprilysin signaling: A comprehensive review

Peptidases are emerging as promising drug targets in tumour suppression. Neprilysin, also known as neutral endopeptidase, is a cell surface peptidase that degrades various peptides such as angiotensin II, endothelin I, Substance P, etc., and reduces their local concentration. Neprilysin is expressed in various tissues such as kidney, prostate, lung, breast, brain, intestine, adrenal gland, etc. The tumour-suppressor mechanisms of neprilysin include its peptidase activity that degrades mitogenic growth factors such as fibroblast growth factor-2 and insulin-like growth factors, and the protein-protein interaction of neprilysin with phosphatase and tensin homolog, focal adhesion kinase, ezrin/radixin/moesin, and phosphoinositide 3-kinase. Studies have shown that the levels of neprilysin play an important role in malignancies. NEP is downregulated in prostate, renal, lung, breast, urothelial, cervical, hepatic cancers, etc. Histone deacetylation and hypermethylation of the neprilysin promoter region are the common mechanisms involved in the downregulation of neprilysin. Downregulation of the peptidase promotes angiogenesis, cell survival and cell migration. This review presents an overview of the role of neprilysin in malignancy, the tumour suppression mechanisms of neprilysin, the epigenetic mechanisms responsible for downregulation of neprilysin, and the potential pharmacological approaches to upregulate neprilysin levels and its activity.

[Molecular pathology of urogenital tumors : Recommendations from the 2019 International Society of Urological Pathology (ISUP) Consensus Conference]

Das zunehmende Verständnis molekularer Grundlagen von Tumoren sowie der Fortschritt in der Diversifizierung der onkologischen Therapien versprechen individualisierte Therapieoptionen, welche bislang jedoch nur ansatzweise in die Therapieplanung von urologischen Tumoren eingegangen sind. Daher hat die Internationale Gesellschaft für Urologische Pathologie (ISUP) im März 2019 eine Konsenskonferenz zur Erarbeitung evidenzbasierter Handlungsempfehlungen zur molekularpathologischen Diagnostik beim Urothelkarzinom, Nierenzellkarzinom, Prostatakarzinom, Peniskarzinom und testikulären Keimzelltumoren durchgeführt. Die auf dieser Konsenskonferenz erarbeiteten Empfehlungen sind kürzlich in 5 separaten Manuskripten veröffentlich worden und werden in der vorliegenden Arbeit zusammengefasst.

Im Rahmen der Konferenzvorbereitung wurde eine umfassende Umfrage zur derzeitigen Praxis molekularer Testungen bei urogenitalen Tumoren unter den Mitgliedern der ISUP durchgeführt. Auf der Konferenz wurden die Ergebnisse und die entsprechenden Hintergrundinformationen durch 5 Arbeitsgruppen präsentiert und Handlungsempfehlungen für die Diagnostik erarbeitet. Eine Übereinstimmung von 66 % der Konferenzteilnehmer wurde als Konsens definiert.

Macropinocytosis: mechanism and targeted therapy in cancers

Macropinocytosis is a form of endocytosis which provides an effective way for non-selective uptakes of extracellular proteins, liquids, and particles. The endocytic process is initiated by the activation of the growth factors signaling pathways. After activation of the biochemical signal, the cell starts internalizing extracellular solutes and nutrients into the irregular endocytic vesicles, known as macropinosomes that deliver them into the lysosomes for degradation. Macropinocytosis plays an important role in the nutritional supply of cancer cells. Due to the rapid expansion of cancer cells and the abnormal vascular microenvironment, cancer cells are usually deprived of oxygen and nutrients. Therefore, they must transform their metabolism to survive and grow in this harsh microenvironment. To satisfy their energy needs, cancer cells enhance the activity of macropinocytosis. Therefore, this metabolic adaptation that is used by cancer cells can be exploited to develop new targeted cancer therapies. In this review, we discuss the molecular mechanism that actuates the process of macropinocytosis in a variety of cancers, and the novel anti-cancer therapeutics in targeting macropinocytosis.

Identifying the role of apolipoprotein A-I in prostate cancer

Although localized prostate cancer (PCa) can be cured by prostatectomy and radiotherapy, the development of effective therapeutic approaches for advanced prostate cancer, including castration-resistant PCa (CRPC) and neuroendocrine PCa (NEPC), is lagging far behind. Identifying a novel prognostic and diagnostic biomarker for early diagnosis and intervention is an urgent clinical need. Here, we report that apolipoprotein A-I (ApoA-I), the major component of high-density lipoprotein (HDL), is upregulated in PCa based on both bioinformatics and experimental evidence. The fact that advanced PCa shows strong ApoA-I expression reflects its potential role in driving therapeutic resistance and disease progression by reprogramming the lipid metabolic network of tumor cells. Molecularly, ApoA-I is regulated by MYC, a frequently amplified oncogene in late-stage PCa. Altogether, our findings have revealed a novel indicator to predict prognosis and recurrence, which would benefit patients who are prone to progress to metastasis or even NEPC, which is the lethal subtype of PCa.

The steroid hormone 20-hydroxyecdysone counteracts insulin signaling via insulin receptor dephosphorylation

The insulin receptor (INSR) binds insulin to promote body growth and maintain normal blood glucose levels. While it is known that steroid hormones such as estrogen and 20-hydroxyecdysone counteract insulin function, the molecular mechanisms responsible for this attenuation remain unclear. In the present study, using the agricultural pest lepidopteran Helicoverpa armigera as a model, we proposed that the steroid hormone 20-hydroxyecdysone (20E) induces dephosphorylation of INSR to counteract insulin function. We observed high expression and phosphorylation of INSR during larval feeding stages that decreased during metamorphosis. Insulin upregulated INSR expression and phosphorylation, whereas 20E repressed INSR expression and induced INSR dephosphorylation in vivo. Protein tyrosine phosphatase 1B (PTP1B, encoded by Ptpn1) dephosphorylated INSR in vivo. PTEN (phosphatase and tensin homolog deleted on chromosome 10) was critical for 20E-induced INSR dephosphorylation by maintaining the transcription factor Forkhead box O (FoxO) in the nucleus, where FoxO promoted Ptpn1 expression and repressed Insr expression. Knockdown of Ptpn1 using RNA interference maintained INSR phosphorylation, increased 20E production, and accelerated pupation. RNA interference of Insr in larvae repressed larval growth, decreased 20E production, delayed pupation, and accumulated hemolymph glucose levels. Taken together, these results suggest that a high 20E titer counteracts the insulin pathway by dephosphorylating INSR to stop larval growth and accumulate glucose in the hemolymph.

Expression, Localization, and Function of the Nucleolar Protein BOP1 in Prostate Cancer Progression

Differentiating between indolent and aggressive prostate cancers (CaP) is important to decrease overtreatment and increase survival for men with the aggressive disease. Nucleolar prominence is a histologic hallmark of CaP; however, the expression, localization, and functional significance of specific nucleolar proteins have not been investigated thoroughly. The nucleolar protein block of proliferation 1 (BOP1) is associated with multiple cancers but has not been implicated in CaP thus far. Meta-analysis of publicly available data showed increased BOP1 expression in metastatic CaP and recurrent CaP, and was inversely associated with overall survival. Multiplexed immunohistochemistry was used to analyze expression and localization of BOP1 and nucleolar protein 56 in human tissue samples from various stages of CaP progression. Here, increased BOP1 expression was observed at later stages of CaP progression, coinciding with a localization change from nuclear to cytoplasmic. In patient samples, cytoplasmic BOP1 was also inversely associated with overall survival. In models of prostate cancer progression, BOP1 expression showed expression and localization similar to that in human patient samples. The functional significance of BOP1 in metastatic CaP was assessed by genetic knockdown, where BOP1 knockdown resulted in decreased proliferation and motility compared with control. Taken together, these data suggest prognostic significance of BOP1 expression and localization in CaP progression and provide a foundation for further investigation into the functional role of nucleolar proteins in advanced CaP.

BAP1 suppresses prostate cancer progression by deubiquitinating and stabilizing PTEN

Deubiquitinase BAP1 is an important tumor suppressor in several malignancies, but its functions and critical substrates in prostate cancer (PCa) remain unclear. Here, we report that the mRNA and protein expression levels of BAP1 are downregulated in clinical PCa specimens. BAP1 can physically bind to and deubiquitinate PTEN, which inhibits the ubiquitination-mediated degradation of PTEN and thus stabilizes PTEN protein. Ectopically expressed BAP1 in PCa cells increases PTEN protein level and subsequently inhibits the AKT signaling pathway, thus suppressing PCa progression. Conversely, knockdown of BAP1 in PCa cells leads to the decrease in PTEN protein level and the activation of the Akt signaling pathway, therefore promoting malignant transformation and cancer metastasis. However, these can be reversed by the re-expression of PTEN. More importantly, we found that BAP1 protein level positively correlates with PTEN in a substantial fraction of human cancers. These findings demonstrate that BAP1 is an important deubiquitinase of PTEN for its stability and the BAP1-PTEN signaling axis plays a crucial role in tumor suppression.

A review of current clinical biomarkers for prostate cancer: towards personalised and targeted therapy

Background:

Prostate cancer is the most commonly diagnosed cancer in men and it is responsible for about 10% of all cancer mortality in Canadian men. The current ‘gold standard’ for the diagnosis of prostate cancer is a prostate biopsy and the decision on when to biopsy a patient with non-suspicious Digital Rectal Examination (DRE) result and total prostate specific antigen (tPSA) of 4–10 ng/ml can be challenging. In order to shift the treatment paradigm of prostate cancer toward more personalised and targeted therapy, there is the need for a clear system that makes its detection binary so as to decrease the rate of inaccurate detections. Therefore in recent years, there have been several investigations into the development of various biomarkers with high sensitivity and specificity for screening, early detection and personalised patient-specific targeted medicine from diagnosis to treatment of the disease.

Materials and methods:

This paper reports on nine currently available clinical biomarkers used in screening for early detection and diagnosis, to reduce the number of unnecessary biopsies, in risk assessment of aggressive disease and in monitoring treatment response of prostate cancer.

Conclusion:

Current clinical prostate cancer biomarkers have the potential for a personalised risk assessment of aggressive disease and the risk of developing distant metastatic disease and have been proven to be useful tools to guide clinicians in personalised patient-specific targeted treatment and in the shared decision making between patients and their physicians regarding prostate biopsy and treatment. Using biomarkers to select patients with a significant probability of aggressive prostate cancer would potentially avoid premature death from the disease, while at the same time would safely preclude patients who do not require unnecessary invasive intervention.

Cerina: systematic circRNA functional annotation based on integrative analysis of ceRNA interactions

Circular RNAs, a family of covalently circularized RNAs with tissue-specific expression, were recently demonstrated to play important roles in mammalian biology. Regardless of extensive research to predict, quantify, and annotate circRNAs, our understanding of their functions is still in its infancy. In this study, we developed a novel computational tool: Competing Endogenous RNA for INtegrative Annotations (Cerina), to predict biological functions of circRNAs based on the competing endogenous RNA model. Pareto Frontier Analysis was employed to integrate ENCODE mRNA/miRNA data with predicted microRNA response elements to prioritize tissue-specific ceRNA interactions. Using data from several circRNA-disease databases, we demonstrated that Cerina significantly improved the functional relevance of the prioritized ceRNA interactions by several folds, in terms of precision and recall. Proof-of-concept studies on human cancers and cardiovascular diseases further showcased the efficacy of Cerina on predicting potential circRNA functions in human diseases.

Genetic ablation of FASN attenuates the invasive potential of prostate cancer driven by Pten loss

Loss of the tumor suppressor gene Pten in murine prostate recapitulates human carcinogenesis and causes stromal proliferation surrounding murine prostate intraepithelial neoplasia (mPIN), which is reactive to microinvasion. In turn, invasion has been shown to be regulated in part by de novo fatty acid synthesis in prostate cancer. We therefore investigated the effects of genetic ablation of Fasn on invasive potential in prostate‐specific Pten knockout mice. Combined genetic ablation of Fasn and Pten reduced the weight and volume of all the prostate lobes when compared to single knockouts. The stromal reaction to microinvasion and the cell proliferation that typically occurs in Pten knockout were largely abolished by Fasn knockout. To verify that Fasn knockout indeed results in decreased invasive potential, we show that genetic ablation and pharmacologic inhibition of FASN in prostate cancer cells significantly inhibit cellular motility and invasion. Finally, combined loss of PTEN with FASN overexpression was associated with lethality as assessed in 660 prostate cancer patients with 14.2 years of median follow‐up. Taken together, these findings show that de novo lipogenesis contributes to the aggressive phenotype induced by Pten loss in murine prostate and targeting Fasn may reduce the invasive potential of prostate cancer driven by Pten loss. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Arguments against using an abbreviated or biparametric prostate MRI protocol

Currently there is a lot of interest in the use of a "biparametric" or "abbreviated" prostate MR protocol, which usually refers to removal of the dynamic contrast-enhanced (DCE) MRI, in the detection of clinically significant prostate cancer. In this article we describe the benefits of DCE as part of the PI-RADS lexicon, with particular reference to its role in PI-RADS V2 category 3 peripheral zone lesions. We also discuss the benefits of triplanar T2-weighted images, and finally discuss how a mpMRI protocol is of benefit in prostate cancer staging, in evaluating for local disease recurrence, and as a biomarker for neoadjuvant therapy response.

Activation of PAR2 by tissue factor induces the release of the PTEN from MAGI proteins and regulates PTEN and Akt activities

Tissue factor (TF) signalling has been associated with alterations in Akt activity influencing cellular survival and proliferation. TF is also shown to induce signalling through activation of the protease activated receptor (PAR)2. Seven cell lines were exposed to recombinant-TF (rec-TF), or activated using a PAR2-agonist peptide and the phosphorylation state of PTEN, and the activities of PTEN and Akt measured. Furthermore, by measuring the association of PTEN with MAGI proteins a mechanism for the induction of signalling by TF was proposed. Short term treatment of cells resulted in de-phosphorylation of PTEN, increased lipid-phosphatase activity and reduced Akt kinase activity in most of the cell lines examined. In contrast, continuous exposure to rec-TF up to 14 days, resulted in lower PTEN antigen levels, enhanced Akt activity and increased rate of cell proliferation. To explore the mechanism of activation of PTEN by TF, the association of "membrane-associated guanylate kinase-with inverted configuration" (MAGI)1–3 proteins with PTEN was assessed using the proximity ligation assay and by co-immunoprecipitation. The interaction of PTEN with all three MAGI proteins was transiently reduced following PAR2 activation and explains the changes in PTEN activity. Our data is first to show that PAR2 activation directly, or through exposure of cells to TF releases PTEN from MAGI proteins and is concurrent with increases in PTEN phosphatase activity. However, prolonged exposure to TF results in the reduction in PTEN antigen with concurrent increase in Akt activity which may explain the aberrant cell survival, proliferation and invasion associated with TF during chronic diseases.

FRMD6 has tumor suppressor functions in prostate cancer

Available tools for prostate cancer (PC) prognosis are suboptimal but may be improved by better knowledge about genes driving tumor aggressiveness. Here, we identified FRMD6 (FERM domain-containing protein 6) as an aberrantly hypermethylated and significantly downregulated gene in PC. Low FRMD6 expression was associated with postoperative biochemical recurrence in two large PC patient cohorts. In overexpression and CRISPR/Cas9 knockout experiments in PC cell lines, FRMD6 inhibited viability, proliferation, cell cycle progression, colony formation, 3D spheroid growth, and tumor xenograft growth in mice. Transcriptomic, proteomic, and phospho-proteomic profiling revealed enrichment of Hippo/YAP and c-MYC signaling upon FRMD6 knockout. Connectivity Map analysis and drug repurposing experiments identified pyroxamide as a new potential therapy for FRMD6 deficient PC cells. Finally, we established orthotropic Frmd6 and Pten, or Pten only (control) knockout in the ROSA26 mouse prostate. After 12 weeks, Frmd6/Pten double knockouts presented high-grade prostatic intraepithelial neoplasia (HG-PIN) and hyperproliferation, while Pten single-knockouts developed only regular PIN lesions and displayed lower proliferation. In conclusion, FRMD6 was identified as a novel tumor suppressor gene and prognostic biomarker candidate in PC.

Oncogenic activation of PI3K-AKT-mTOR signaling suppresses ferroptosis via SREBP-mediated lipogenesis

Ferroptosis, a form of regulated necrosis driven by iron-dependent peroxidation of phospholipids, is regulated by cellular metabolism, redox homeostasis, and various signaling pathways related to cancer. In this study, we found that activating mutation of phosphatidylinositol 3-kinase (PI3K) or loss of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) function, highly frequent events in human cancer, confers ferroptosis resistance in cancer cells, and that inhibition of the PI3K-AKT-mTOR signaling axis sensitizes cancer cells to ferroptosis induction. Mechanistically, this resistance requires sustained activation of mTORC1 and the mechanistic target of rapamycin (mTOR)C1-dependent induction of sterol regulatory element-binding protein 1 (SREBP1), a central transcription factor regulating lipid metabolism. Furthermore, stearoyl-CoA desaturase-1 (SCD1), a transcriptional target of SREBP1, mediates the ferroptosis-suppressing activity of SREBP1 by producing monounsaturated fatty acids. Genetic or pharmacologic ablation of SREBP1 or SCD1 sensitized ferroptosis in cancer cells with PI3K-AKT-mTOR pathway mutation. Conversely, ectopic expression of SREPB1 or SCD1 restored ferroptosis resistance in these cells, even when mTORC1 was inhibited. In xenograft mouse models for PI3K-mutated breast cancer and PTEN-defective prostate cancer, the combination of mTORC1 inhibition with ferroptosis induction resulted in near-complete tumor regression. In conclusion, hyperactive mutation of PI3K-AKT-mTOR signaling protects cancer cells from oxidative stress and ferroptotic death through SREBP1/SCD1-mediated lipogenesis, and combination of mTORC1 inhibition with ferroptosis induction shows therapeutic promise in preclinical models.

Molecular pathology of prostate cancer: a practical approach

While localised prostate cancer can be cured by local treatment, 'high-risk' prostate cancer often progresses to castration resistant disease and remains incurable with a dismal prognosis. In recent years, technical advances and development of novel methodologies have largely contributed to a better understanding of underlying molecular mechanisms that promote tumour growth and progression. Consecutively, novel therapeutic strategies for treatment of prostate cancer have emerged during the last decade, calling for the identification of predictive biomarkers. The concept of personalised medicine is to tailor treatment according to the specific tumour profile of an individual patient. Moreover, acquired molecular changes during tumour evolution and in response to therapy selection pressure require adapted predictive marker testing at different time points during the disease. In this setting, the pathologist plays a critical role in patient management and treatment selection. In this review, we provide a comprehensive overview of the current knowledge of molecular aspects of prostate cancer and their potential utility in the context of different therapeutic approaches. Furthermore, we discuss methods for molecular marker testing in routine clinical practice, with a focus on castration resistant prostate cancer.

RGS12 Represses Oral Cancer via the Phosphorylation and SUMOylation of PTEN

Oral squamous cell carcinoma (OSCC) is the most common head and neck cancer characterized by aggressive local invasion and metastasis. The pathogenesis of OSCC is mainly due to the accumulation of genetic alterations in epithelial cells, but the underlying mechanism for its development remains unclear. Here, we found that the expression level of regulator of G protein signaling 12 (RGS12) was significantly reduced in human OSCC. To understand the role and mechanism of RGS12 in OSCC, we generated a novel RGS12 global knockout (CMV^Cre/+; RGS12^fl/fl) mouse model by crossing RGS12^fl/fl mice with CMV-Cre transgenic mice and then further induced the mice to develop OSCC by using 4-nitroquinoline 1-oxide (4NQO). Deletion of RGS12 exhibited aggressive OSCC in the tongue compared with the control RGS12^fl/fl mice. Knockdown of RGS12 in OSCC cells significantly increased cell proliferation and migration. Mechanistically, we found that RGS12 associated with phosphatase and tension homolog (PTEN) via the PDZ domain to upregulate the phosphorylation and SUMOylation of PTEN and then correspondingly inactivated the AKT/mTOR signaling pathway. To test the potential therapeutic effect of RGS12 on OSCC, we overexpressed RGS12 in OSCC cells and found a significant inhibition of cancer cell proliferation and migration. Moreover, subcutaneous inoculation of RGS12-overexpressed OSCC cells in NOD scid mice showed a significant reduction in tumor formation. Our findings reveal that RGS12 is an essential tumor suppressor and highlights RGS12 as a potential therapeutic target and prognostic biomarker of OSCC.

Intraductal Carcinoma of the Prostate: Pathogenesis and Molecular Perspectives

Intraductal carcinoma of the prostate (IDC-P), a clinicopathological entity characterized by malignant prostatic epithelial cells growing within ducts and/or acini, has a distinct architectural pattern, cytological features, and biological behavior. Whereas most IDC-P tumors could be derived from adjacent high-grade invasive cancer via retrograde spreading of cancer cells along benign ducts and acini, a small subset of IDC-P may arise from the transformation and intraductal proliferation of precancerous cells induced by various oncogenic events. These isolated IDC-P tumors possess a distinct mutational profile and may function as a carcinoma in situ lesion with de novo intraductal outgrowth of malignant cells. Further molecular characterization of these two types of IDC-P and better understanding of the mechanisms underlying IDC-P formation and progression could be translated into valuable biomarkers for differential diagnosis and actionable targets for therapeutic interventions. PATIENT SUMMARY: Intraductal carcinoma of the prostate is an aggressive type of prostate cancer associated with high risk for local recurrence and distant metastasis. In this review, we discussed pathogenesis, biomarkers, differential diagnoses, and therapeutic strategies for this tumor.

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.

Phosphatase and Tensin Homolog (PTEN) of Japanese Flounder-Its Regulation by miRNA and Role in Autophagy, Apoptosis and Pathogen Infection

MicroRNAs (miRNAs) are small non-coding RNAs with important roles in diverse biological processes including immunity. Japanese flounder (Paralichthys olivaceus) is an aquaculture fish species susceptible to the infection of bacterial and viral pathogens including Edwardsiella tarda. In a previous study, pol-miR-novel_547, a novel miRNA of flounder with unknown function, was found to be induced by E. tarda. In the present study, we investigated the regulation and function of pol-miR-novel_547 and its target gene. We found that pol-miR-novel_547 was regulated differently by E. tarda and the viral pathogen megalocytivirus, and pol-miR-novel_547 repressed the expression of PTEN (phosphatase and tensin homolog) of flounder (PoPTEN). PoPTEN is ubiquitously expressed in multiple tissues of flounder and responded to bacterial and viral infections. Interference with PoPTEN expression in flounder cells directly or via pol-miR-novel_547 promoted E. tarda invasion. Consistently, in vivo knockdown of PoPTEN enhanced E. tarda dissemination in flounder tissues, whereas in vivo overexpression of PoPTEN attenuated E. tarda dissemination but facilitated megalocytivirus replication. Further in vitro and in vivo studies showed that PoPTEN affected autophagy activation via the AKT/mTOR pathway and also modulated the process of apoptosis. Together these results reveal for the first time a critical role of fish PTEN and its regulatory miRNA in pathogen infection, autophagy, and apoptosis.

Estrogen receptor β regulates AKT activity through up-regulation of INPP4B and inhibits migration of prostate cancer cell line PC-3

Loss of the tumor suppressor, PTEN, is one of the most common findings in prostate cancer (PCa). This loss leads to overactive Akt signaling, which is correlated with increased metastasis and androgen independence. However, another tumor suppressor, inositol-polyphosphate 4-phosphatase type II (INPP4B), can partially compensate for the loss of PTEN. INPP4B is up-regulated by androgens, and this suggests that androgen-deprivation therapy (ADT) would lead to hyperactivity of AKT. However, in the present study, we found that in PCa, samples from men treated with ADT, ERβ, and INPP4B expression were maintained in some samples. To investigate the role of ERβ1 in regulation of INPPB, we engineered the highly metastatic PCa cell line, PC3, to express ERβ1. In these cells, INPP4B was induced by ERβ ligands, and this induction was accompanied by inhibition of Akt activity and reduction in cell migration. These findings reveal that, in the absence of androgens, ERβ1 induces INPP4B to dampen AKT signaling. Since the endogenous ERβ ligand, 3β-Adiol, is lost upon long-term ADT, to obtain the beneficial effects of ERβ1 on AKT signaling, an ERβ agonist should be added along with ADT.

Incorporating Prognostic Biomarkers into Risk Assessment Models and TNM Staging for Prostate Cancer

In current practice, prostate cancer staging alone is not sufficient to adequately assess the patient's prognosis and plan the management strategies. Multiple clinicopathological parameters and risk tools for prostate cancer have been developed over the past decades to better characterize the disease and provide an enhanced assessment of prognosis. Herein, we review novel prognostic biomarkers and their integration into risk assessment models for prostate cancer focusing on their capability to help avoid unnecessary imaging studies, biopsies and diagnosis of low risk prostate cancers, to help in the decision-making process between active surveillance and treatment intervention, and to predict recurrence after radical prostatectomy. There is an imperative need of reliable biomarkers to stratify prostate cancer patients that may benefit from different management approaches. The integration of biomarkers panel with risk assessment models appears to improve prostate cancer diagnosis and management. However, integration of novel genomic biomarkers in future prognostic models requires further validation in their clinical efficacy, standardization, and cost-effectiveness in routine application.

Cellular and Molecular Progression of Prostate Cancer: Models for Basic and Preclinical Research

Simple Summary

The molecular progression of prostate cancer is complex and elusive. Biological research relies heavily on in vitro and in vivo models that can be used to examine gene functions and responses to the external agents in laboratory and preclinical settings. Over the years, several models have been developed and found to be very helpful in understanding the biology of prostate cancer. Here we describe these models in the context of available information on the cellular and molecular progression of prostate cancer to suggest their potential utility in basic and preclinical prostate cancer research. The information discussed herein should serve as a hands-on resource for scholars engaged in prostate cancer research or to those who are making a transition to explore the complex biology of prostate cancer.

Abstract

We have witnessed noteworthy progress in our understanding of prostate cancer over the past decades. This basic knowledge has been translated into efficient diagnostic and treatment approaches leading to the improvement in patient survival. However, the molecular pathogenesis of prostate cancer appears to be complex, and histological findings often do not provide an accurate assessment of disease aggressiveness and future course. Moreover, we also witness tremendous racial disparity in prostate cancer incidence and clinical outcomes necessitating a deeper understanding of molecular and mechanistic bases of prostate cancer. Biological research heavily relies on model systems that can be easily manipulated and tested under a controlled experimental environment. Over the years, several cancer cell lines have been developed representing diverse molecular subtypes of prostate cancer. In addition, several animal models have been developed to demonstrate the etiological molecular basis of the prostate cancer. In recent years, patient-derived xenograft and 3-D culture models have also been created and utilized in preclinical research. This review is an attempt to succinctly discuss existing information on the cellular and molecular progression of prostate cancer. We also discuss available model systems and their tested and potential utility in basic and preclinical prostate cancer research.

Natural antisense transcripts in the biological hallmarks of cancer: powerful regulators hidden in the dark

Natural antisense transcripts (NATs), which are transcribed from opposite strands of DNA with partial or complete overlap, affect multiple stages of gene expression, from epigenetic to post-translational modifications. NATs are dysregulated in various types of cancer, and an increasing number of studies focusing on NATs as pivotal regulators of the hallmarks of cancer and as promising candidates for cancer therapy are just beginning to unravel the mystery. Here, we summarize the existing knowledge on NATs to highlight their underlying mechanisms of functions in cancer biology, discuss their potential roles in therapeutic application, and explore future research directions.

Multiplex Immunofluorescence in Formalin-Fixed Paraffin-Embedded Tumor Tissue to Identify Single-Cell-Level PI3K Pathway Activation

PURPOSE

Identifying cancers with high PI3K pathway activity is critical for treatment selection and eligibility into clinical trials of PI3K inhibitors. Assessments of tumor signaling pathway activity need to consider intratumoral heterogeneity and multiple regulatory nodes.

EXPERIMENTAL DESIGN

We established a novel, mechanistically informed approach to assessing tumor signaling pathways by quantifying single-cell-level multiplex immunofluorescence using custom algorithms. In a proof-of-concept study, we stained archival formalin-fixed, paraffin-embedded (FFPE) tissue from patients with primary prostate cancer in two prospective cohort studies, the Health Professionals Follow-up Study and the Physicians' Health Study. PTEN, stathmin, and phospho-S6 were quantified on 14 tissue microarrays as indicators of PI3K activation to derive cell-level PI3K scores.

RESULTS

In 1,001 men, 988,254 tumor cells were assessed (median, 743 per tumor; interquartile range, 290-1,377). PI3K scores were higher in tumors with PTEN loss scored by a pathologist, higher Gleason grade, and a new, validated bulk PI3K transcriptional signature. Unsupervised machine-learning approaches resulted in similar clustering. Within-tumor heterogeneity in cell-level PI3K scores was high. During long-term follow-up (median, 15.3 years), rates of progression to metastases and death from prostate cancer were twice as high in the highest quartile of PI3K activation compared with the lowest quartile (hazard ratio, 2.04; 95% confidence interval, 1.13-3.68).

CONCLUSIONS

Our novel pathway-focused approach to quantifying single-cell-level immunofluorescence in FFPE tissue identifies prostate tumors with PI3K pathway activation that are more aggressive and may respond to pathway inhibitors.

Darolutamide antagonizes androgen signaling by blocking enhancer and super-enhancer activation

Prostate cancer (PCa) is one of the most frequent tumor types in the male Western population. Early-stage PCa and late-stage PCa are dependent on androgen signaling, and inhibitors of the androgen receptor (AR) axis represent the standard therapy. Here, we studied in detail the global impact of darolutamide, a newly approved AR antagonist, on the transcriptome and AR-bound cistrome in two PCa cell models. Darolutamide strongly depleted the AR from gene regulatory regions and abolished AR-driven transcriptional signaling. Enhancer activation was blocked at the chromatin level as evaluated by H3K27 acetylation (H3K27ac), H3K4 monomethylation (H3K4me1), and FOXA1, MED1, and BRD4 binding. We identified genomic regions with high affinities for the AR in androgen-stimulated, but also in androgen-depleted conditions. A similar AR affinity pattern was observed in healthy and PCa tissue samples. High FOXA1, BRD4, H3K27ac, and H3K4me1 levels were found to mark regions showing AR binding in the hormone-depleted setting. Conversely, low FOXA1, BRD4, and H3K27ac levels were observed at regulatory sites that responded strongly to androgen stimulation, and AR interactions at these sites were blocked by darolutamide. Beside marked loss of AR occupancy, FOXA1 recruitment to chromatin was also clearly reduced after darolutamide treatment. We furthermore identified numerous androgen-regulated super-enhancers (SEs) that were associated with hallmark androgen and cell proliferation-associated gene sets. Importantly, these SEs are also active in PCa tissues and sensitive to darolutamide treatment in our models. Our findings demonstrate that darolutamide is a potent AR antagonist blocking genome-wide AR enhancer and SE activation, and downstream transcription. We also show the existence of a dynamic AR cistrome that depends on the androgen levels and on high AR affinity regions present in PCa cell lines and also in tissue samples.

PTEN in osteosarcoma: Recent advances and the therapeutic potential

Osteosarcoma is the most common primary malignant bone tumor, predominantly occurring in children and adolescents. Despite treated with surgery and neoadjuvant chemotherapy, osteosarcoma has a high potential of local recurrence and lung metastasis. Overall survival rates for osteosarcoma have plateaued in the past four decades, therefore, identification of novel targets and development of more effective treatment strategies are urgent. Phosphatase and tensin homolog (PTEN) is a tumor suppressor gene that negatively regulates the phosphatidylinositol 3-kinase (PI3K)/ protein kinase B (AKT)/ mammalian target of rapamycin (mTOR) pathway. Over half of clinical osteosarcoma samples presented loss or low expression of PTEN, which usually indicated an advanced stage of tumor and a poor prognosis. The expression of PTEN is regulated by epigenetic silence, transcription regulation, post-translational modifications, and protein interactions in osteosarcoma. Therefore, explicating regulations to restore the anti-tumor function of PTEN might provide novel targeted therapies for osteosarcoma. Preclinical evidence suggested directly targeting the altered PTEN in osteosarcoma was promising. Current clinical application of PTEN related therapies in osteosarcoma are PI3K/mTOR inhibitors, and these drugs have shown the favorable efficacy in patients with advanced osteosarcoma.