Database-augmented Mass Spectrometry Analysis of Exosomes Identifies Claudin 3 as a Putative Prostate Cancer Biomarker

Small extracellular vesicles: Roles and clinical application in prostate cancer

Prostate cancer is a significant health problem in the United States. It is remarkably heterogenous, ranging from slow growing disease amenable to active surveillance to highly aggressive forms requiring active treatments. Therefore, being able to precisely determine the nature of disease and appropriately match patients to available and/or novel therapeutics is crucial to improve patients' overall outcome and quality of life. Recently small extracellular vesicles (sEVs), a subset of nanoscale membranous vesicles secreted by various cells, have emerged as important analytes for liquid biopsy and promising vehicles for drug delivery. sEVs contain various biomolecules such as genetic material, proteins, and lipids that recapitulate the characteristics and state of their donor cells. The application of existing and newly developed technologies has resulted in an increased depth of knowledge about biophysical structures, biogenesis, and functions of sEVs. In prostate cancer patients, tumor-derived sEVs can be isolated from biofluids, commonly urine and blood. They mediate intercellular signaling within the tumor microenvironment and distal organ-specific sites, supporting cancer initiation, progression, and metastasis. A mounting body of evidence suggests that sEV components can be potent biomarkers for prostate cancer diagnosis, prognosis, and prediction of disease progression and treatment response. Due to enhanced circulation stability and bio-barrier permeability, sEVs can be also used as effective drug delivery carriers to improve the efficacy and specificity of anti-tumor therapies. This review discusses recent studies on sEVs in prostate cancer and is focused on their role as biomarkers and drug delivery vehicles in the clinical management of prostate cancer.

Immune capture and protein profiling of small extracellular vesicles from human plasma

Extracellular vesicles (EVs), the key players in inter-cellular communication, are produced by all cell types and are present in all body fluids. Analysis of the proteome content is an important approach in structural and functional studies of these vesicles. EVs circulating in human plasma are heterogeneous in size, cellular origin, and functions. This heterogeneity and the potential presence of contamination with plasma components such as lipoprotein particles and soluble plasma proteins represent a challenge in profiling the proteome of EV subsets by mass spectrometry. An immunocapture strategy prior to mass spectrometry may be used to isolate a homogeneous subpopulation of small EVs (sEV) with a specific endocytic origin from plasma or other biofluids. Immunocapture selectively separates EV subpopulations in biofluids based on the presence of a unique protein carried on the vesicle surface. The advantages and disadvantages of EV immune capture as a preparative step for mass spectrometry are discussed.

Harnessing tumor-derived exosomes: A promising approach for the expansion of clinical diagnosis, prognosis, and therapeutic outcome of prostate cancer

Prostate cancer is the second leading cause of men's death worldwide. Although early diagnosis and therapy for localized prostate cancer have improved, the majority of men with metastatic disease die from prostate cancer annually. Therefore, identification of the cellular-molecular mechanisms underlying the progression of prostate cancer is essential for overcoming controlled proliferation, invasion, and metastasis. Exosomes are small extracellular vesicles that mediate most cells' interactions and contain membrane proteins, cytosolic and nuclear proteins, extracellular matrix proteins, lipids, metabolites, and nucleic acids. Exosomes play an essential role in paracrine pathways, potentially influencing Prostate cancer progression through a wide variety of mechanisms. In the present review, we outline and discuss recent progress in our understanding of the role of exosomes in the Prostate cancer microenvironment, like their involvement in prostate cancer occurrence, progression, angiogenesis, epithelial-mesenchymal transition, metastasis, and drug resistance. We also present the latest findings regarding the function of exosomes as biomarkers, direct therapeutic targets in prostate cancer, and the challenges and advantages associated with using exosomes as natural carriers and in exosome-based immunotherapy. These findings are a promising avenue for the expansion of potential clinical approaches.

Claudins in genitourinary tract neoplasms: mechanisms, prognosis, and therapeutic prospects

Genitourinary (GU) cancers are among the most prevalent neoplasms in the world, with bladder cancers constituting 3% of global cancer diagnoses. However, several pathogenetic mechanisms remain controversial and unclear. Claudins, for example, have been shown to play a significant role in several cancers of the human body. Their role in GU cancers has not been extensively studied. Aberrant expression of claudins -1, -2, -3, -4, -7, and -11 has been expressed in urothelial cell carcinomas. In prostate cancers, altered levels of claudins -1, -2, -3, -4, and -5 have been reported. Furthermore, the levels of claudins -1, -2, -3, -4, -6, -7, -8, and -10 have been studied in renal cell carcinomas. Specifically, claudins -7 and -8 have proven especially useful in differentiating between chromophobe renal cell carcinomas and oncocytomas. Several of these claudins also correlate with clinicopathologic parameters and prognosis in GU cancers. Although mechanisms underpinning aberrant expression of claudins in GU cancers are unclear, epigenetic changes, tumor necrosis factor-ɑ, and the p63 protein have been implicated. Claudins also provide therapeutic value through tailored immunotherapy via molecular subtyping and providing therapeutic targets, which have shown positive outcomes in preclinical studies. In this review, we aim to summarize the literature describing aberrant expression of claudins in urothelial, prostatic, and renal cell carcinomas. Then, we describe the mechanisms underlying these changes and the therapeutic value of claudins. Understanding the scope of claudins in GU cancers paves the way for several diagnostic, prognostic, and therapeutic innovations.

Prostate cancer-derived small extracellular vesicle proteins: the hope in diagnosis, prognosis, and therapeutics

Current diagnostic tools for prostate cancer (PCa) diagnosis and risk stratification are insufficient. The hidden onset and poor efficacy of traditional therapies against metastatic PCa make this disease a heavy burden in global men's health. Prostate cancer-derived extracellular vesicles (PCDEVs) have garnered attention in recent years due to their important role in communications in tumor microenvironment. Recent advancements have demonstrated PCDEVs proteins play an important role in PCa invasion, progression, metastasis, therapeutic resistance, and immune escape. In this review, we briefly discuss the applications of sEV proteins in PCa diagnosis and prognosis in liquid biopsy, focus on the roles of the PCa-derived small EVs (sEVs) proteins in tumor microenvironment associated with cancer progression, and explore the therapeutic potential of sEV proteins applied for future metastatic PCa therapy.

Liquid Biopsies, Novel Approaches and Future Directions

Cancer is among the leading causes of death worldwide. Early diagnosis and prognosis are vital to improve patients' outcomes. The gold standard of tumor characterization leading to tumor diagnosis and prognosis is tissue biopsy. Amongst the constraints of tissue biopsy collection is the sampling frequency and the incomplete representation of the entire tumor bulk. Liquid biopsy approaches, including the analysis of circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), circulating miRNAs, and tumor-derived extracellular vesicles (EVs), as well as certain protein signatures that are released in the circulation from primary tumors and their metastatic sites, present a promising and more potent candidate for patient diagnosis and follow up monitoring. The minimally invasive nature of liquid biopsies, allowing frequent collection, can be used in the monitoring of therapy response in real time, allowing the development of novel approaches in the therapeutic management of cancer patients. In this review we will describe recent advances in the field of liquid biopsy markers focusing on their advantages and disadvantages.

A guide to mass spectrometric analysis of extracellular vesicle proteins for biomarker discovery

Exosomes (small extracellular vesicles) in living organisms play an important role in processes such as cell proliferation or intercellular communication. Recently, exosomes have been extensively investigated for biomarker discoveries for various diseases. An important aspect of exosome analysis involves the development of enrichment methods that have been introduced for successful isolation of exosomes. These methods include ultracentrifugation, size exclusion chromatography, polyethylene glycol-based precipitation, immunoaffinity-based enrichment, ultrafiltration, and asymmetric flow field-flow fractionation among others. To confirm the presence of exosomes, various characterization methods have been utilized such as Western blot analysis, atomic force microscopy, electron microscopy, optical methods, zeta potential, visual inspection, and mass spectrometry. Recent advances in high-resolution separations, high-performance mass spectrometry and comprehensive proteome databases have all contributed to the successful analysis of exosomes from patient samples. Herein we review various exosome enrichment methods, characterization methods, and recent trends of exosome investigations using mass spectrometry-based approaches for biomarker discovery.

Claudin-3 Loss of Expression Is a Prognostic Marker in Castration-Resistant Prostate Cancer

Castration-resistant prostate cancer (CRPC) development is the foremost concern after treatment of patients with high risk with locally advanced or metastatic prostate cancer. Androgen receptor (AR) is the main driver of CRPC development, through its interaction with epigenetic modifier genes, placing epigenetics modifications in the forefront of CRPC development. Comparing the DNA methylation and expression profile of androgen-sensitive and -refractory prostate cancer cells, we describe the epigenetic silencing of claudin-3 (CLDN3) in AR positive cells resistant to androgen deprivation (LNCaP-abl). CLDN3 silencing was associated with DNA methylation, loss of histone acetylation and H3K27 methylation, and was re-expressed by the combined treatment with the epigenetic modulators Aza and SAHA. From a functional point of view, CLDN3 loss was associated with increased cellular invasion. Immunohistochemical analysis showed decreased CLDN3 expression in samples from CRPC patients. Interestingly, CLDN3 expression was significantly decreased in samples from patients with high total Gleason score (≥8) and locally advanced tumors. Finally, CLDN3 loss of expression was associated with worse disease-free survival and time to clinical progression. In conclusion, our findings strongly indicate that epigenetic silencing of CLDN3 is a common event in CRPC that could be useful as a molecular marker for the prognosis of prostate cancer patients and to discriminate aggressive from indolent prostate tumors.

Recent developments in biosensing methods for extracellular vesicle protein characterization

Research into extracellular vesicles (EVs) has grown significantly over the last few decades with EVs being widely regarded as a source of biomarkers for human health and disease with massive clinical potential. Secreted by every cell type in the body, EVs report on the internal cellular conditions across all tissue types. Their presence in readily accessible biofluids makes the potential of EV biosensing highly attractive as a noninvasive diagnostic platform via liquid biopsies. However, their small size (50-250 nm), inherent heterogeneity, and the complexity of the native biofluids introduce challenges for effective characterization, thus, limiting their clinical utility. This has led to a surge in the development of various novel EV biosensing techniques, with capabilities beyond those of conventional methods that have been directly transferred from cell biology. In this review, key detection principles used for EV biosensing are summarized, with a focus on some of the most recent and fundamental developments in the field over the last 5 years. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > In Vitro Nanoparticle-Based Sensing.

Extracellular vesicles and particles impact the systemic landscape of cancer

Intercellular cross talk between cancer cells and stromal and immune cells is essential for tumor progression and metastasis. Extracellular vesicles and particles (EVPs) are a heterogeneous class of secreted messengers that carry bioactive molecules and that have been shown to be crucial for this cell-cell communication. Here, we highlight the multifaceted roles of EVPs in cancer. Functionally, transfer of EVP cargo between cells influences tumor cell growth and invasion, alters immune cell composition and function, and contributes to stromal cell activation. These EVP-mediated changes impact local tumor progression, foster cultivation of pre-metastatic niches at distant organ-specific sites, and mediate systemic effects of cancer. Furthermore, we discuss how exploiting the highly selective enrichment of molecules within EVPs has profound implications for advancing diagnostic and prognostic biomarker development and for improving therapy delivery in cancer patients. Altogether, these investigations into the role of EVPs in cancer have led to discoveries that hold great promise for improving cancer patient care and outcome.

Molecular mechanisms and clinical applications of exosomes in prostate cancer

Prostate cancer (PC) is a common tumor in men, and the incidence rate is high worldwide. Exosomes are nanosized vesicles released by all types of cells into multiple biological fluid types. These vesicles contribute to intercellular communication by delivering both nucleic acids and proteins to recipient cells. In recent years, many studies have explored the mechanisms by which exosomes mediate the epithelial-mesenchymal transition, angiogenesis, tumor microenvironment establishment, and drug resistance acquisition in PC, and the mechanisms that have been identified and the molecules involved have provided new perspectives for the possible discovery of novel diagnostic markers in PC. Furthermore, the excellent biophysical properties of exosomes, such as their high stability, high biocompatibility and ability to cross biological barriers, have made exosomes promising candidates for use in novel targeted drug delivery system development. In this review, we summarize the roles of exosomes in the growth and signal transmission in PC and show the promising future of exosome contributions to PC diagnostics and treatment.

DIA-based proteomics analysis of serum-derived exosomal proteins as potential candidate biomarkers for intrahepatic cholestasis in pregnancy

BACKGROUND

Data-independent acquisition (DIA) is one of the most powerful and reproducible proteomic technologies for large-scale digital qualitative and quantitative research. The aim of this study was to use proteomic methodologies for the identification of biomarkers that are over or underexpressed in women with intrahepatic cholestasis of pregnancy (ICP) compared with controls and discover a potential biomarker panel for ICP detection.

METHODS

The participants included 11 ICP patients and 11 healthy pregnant women as controls. The clinical characteristic data and the laboratory biochemical data were collected at the time of recruitment. Then, a data-independent acquisition (DIA)-based proteomics approach was used to identify differentially expressed proteins (DEPs) in serum exosomes between ICP patients and controls. Finally, bioinformatics analysis was used to identify the relevant processes in which these DEPs were involved.

RESULTS

The proteomics results showed that there were 162 DEPs in serum exosomes between pregnant women with ICP and healthy pregnant women, of which 106 were upregulated and 56 were downregulated in ICP. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the identified proteins were functionally related to specific cell processes including apoptosis, lipid metabolism, immune response and cell proliferation, and metabolic disorders, suggesting that these may be primary causative factors in ICP pathogenesis. Meanwhile, complement and coagulation cascades may be closely related to the development of ICP. Receiver operating characteristic curve (ROC) analysis showed that the area under the curve values of Elongation factor 1-alpha 1, Beta-2-glycoprotein I, Zinc finger protein 238, CP protein and Ficolin-3 were all approximately 0.9, indicating the promising diagnostic value of these proteins.

CONCLUSIONS

This preliminary work provides a better understanding of the proteomic alterations in the serum exosomes of pregnant women with ICP.

Roles of Non-Coding RNAs in Primary Biliary Cholangitis

Primary biliary cholangitis (PBC) is an autoimmune-mediated chronic cholestatic liver disease, fatigue, and skin itching are the most common clinical symptoms. Its main pathological feature is the progressive damage and destruction of bile duct epithelial cells. Non-coding RNA (NcRNA, mainly including microRNA, long non-coding RNA and circular RNA) plays a role in the pathological and biological processes of various diseases, especially autoimmune diseases. Many validated ncRNAs are expected to be biomarkers for the diagnosis or treatment of PBC. This review will elucidate the pathogenesis of PBC and help to identify potential ncRNA biomarkers for PBC.

Extracellular Vesicle Proteome in Prostate Cancer: A Comparative Analysis of Mass Spectrometry Studies

Molecular diagnostics based on discovery research holds the promise of improving screening methods for prostate cancer (PCa). Furthermore, the congregated information prompts the question whether the urinary extracellular vesicles (uEV) proteome has been thoroughly explored, especially at the proteome level. In fact, most extracellular vesicles (EV) based biomarker studies have mainly targeted plasma or serum. Therefore, in this study, we aim to inquire about possible strategies for urinary biomarker discovery particularly focused on the proteome of urine EVs. Proteomics data deposited in the PRIDE archive were reanalyzed to target identifications of potential PCa markers. Network analysis of the markers proposed by different prostate cancer studies revealed moderate overlap. The recent throughput improvements in mass spectrometry together with the network analysis performed in this study, suggest that a larger standardized cohort may provide potential biomarkers that are able to fully characterize the heterogeneity of PCa. According to our analysis PCa studies based on urinary EV proteome presents higher protein coverage compared to plasma, plasma EV, and voided urine proteome. This together with a direct interaction of the prostate gland and urethra makes uEVs an attractive option for protein biomarker studies. In addition, urinary proteome based PCa studies must also evaluate samples from bladder and renal cancers to assess specificity for PCa.

Toward the next-generation phyto-nanomedicines: cell-derived nanovesicles (CDNs) for natural product delivery

Phytochemicals are plant-derived bioactive compounds, which have been widely used for therapeutic purposes. Due to the poor water-solubility, low bioavailability and non-specific targeting characteristic, diverse classes of nanocarriers are utilized for encapsulation and delivery of bio-effective agents. Cell-derived nanovesicles (CDNs), known for exosomes or extracellular vesicles (EVs), are biological nanoparticles with multiple functions. Compared to the artificial counterpart, CDNs hold great potential in drug delivery given the higher stability, superior biocompatibility and the lager capability of encapsulating bioactive molecules. Here, we provide a bench-to-bedside review of CDNs-based nanoplatform, including the bio-origin, preparation, characterization and functionalization. Beyond that, the focus is laid on the therapeutic effect of CDNs-mediated drug delivery for natural products. The state-of-art development as well as some pre-clinical applications of using CDNs for disease treatment is also summarized. It is highly expected that the continuing development of CDNs-based delivery systems will further promote the clinical utilization and translation of phyto-nanomedicines.

Claudin-2 promotes colorectal cancer liver metastasis and is a biomarker of the replacement type growth pattern

Claudin-2 promotes breast cancer liver metastasis by enabling seeding and early cancer cell survival. We now demonstrate that Claudin-2 is functionally required for colorectal cancer liver metastasis and that Claudin-2 expression in primary colorectal cancers is associated with poor overall and liver metastasis-free survival. We have examined the role of Claudin-2, and other claudin family members, as potential prognostic biomarkers of the desmoplastic and replacement histopathological growth pattern associated with colorectal cancer liver metastases. Immunohistochemical analysis revealed higher Claudin-2 levels in replacement type metastases when compared to those with desmoplastic features. In contrast, Claudin-8 was highly expressed in desmoplastic colorectal cancer liver metastases. Similar observations were made following immunohistochemical staining of patient-derived xenografts (PDXs) that we have established, which faithfully retain the histopathology of desmoplastic or replacement type colorectal cancer liver metastases. We provide evidence that Claudin-2 status in patient-derived extracellular vesicles may serve as a relevant prognostic biomarker to predict whether colorectal cancer patients have developed replacement type liver metastases. Such a biomarker will be a valuable tool in designing optimal treatment strategies to better manage patients with colorectal cancer liver metastases.

Tabariès et al. describe that claudin 2 is a promoter of colorectal cancer liver metastasis. Furthermore, high Claudin-2 expression is associated with shorter time to liver-specific recurrence and is a biomarker of replacement type CRC liver metastases.

Extracellular vesicles in prostate cancer: a narrative review

Over the past decade, there has been remarkable progress in prostate cancer biomarker discovery using urine- and blood-based assays. A liquid biopsy is a minimally invasive procedure to investigate the cancer-related molecules in circulating tumor cells (CTCs), cell-free DNA, and extracellular vesicles (EVs). Liquid biopsies have the advantage of detecting heterogeneity as well as acquired resistance in cancer. EVs are cell-derived vesicles enclosed by a lipid bilayer and contain various molecules, such as nucleic acids, proteins, and lipids. In patients with cancer, EVs derived from tumors can be isolated from urine, plasma, and serum. The advances in isolation techniques provide the opportunity to use EVs as biomarkers in the clinic. Emerging evidence suggests that EVs can be useful biomarkers for the diagnosis of prostate cancer, especially high-grade cancer. EVs can also be potent biomarkers for the prediction of disease progression in patients with castration-resistant prostate cancer (CRPC). EVs shed from cancer and stromal cells are involved in the development of tumor microenvironments, enhancing cancer progression, metastasis, and drug resistance. Here, we provide an overview of the use of EVs for the diagnosis of clinically significant prostate cancer as well as for predicting disease progression. We also discuss the biological function of EVs, which regulate cancer progression.

Utility of Claudin-3 in extracellular vesicles from human bile as biomarkers of cholangiocarcinoma

Extracellular vesicles (EVs) are released from all cells. Bile directly contacts bile duct tumor; bile-derived EVs may contain high concentrations of cancer biomarkers. We performed a proteomic analysis of human bile-derived EVs and identified a novel biomarker of cholangiocarcinoma (CCA). EVs were isolated using ultracentrifugation, and chelating agents, ethylenediaminetetraacetic acid and ethylene glycol tetraacetic acid (EDEG) and phosphate buffered saline (PBS) were used as dissolution solutions. Bile was collected from 10 CCA and 10 choledocholithiasis (stones) cases. Proteomic analysis was performed; subsequently, ELISA was performed using the candidate biomarkers in a verification cohort. The vesicles isolated from bile had a typical size and morphology. The expression of exosome markers was observed. RNA was more abundant in the EDEG group. The proportion of microRNA was higher in the EDEG group. EDEG use resulted in the removal of more contaminants. Proteomic analysis identified 166 proteins as CCA-specific. ELISA for Claudin-3 revealed statistically significant difference. The diagnostic accuracy was AUC 0.945 and sensitivity and specificity were 87.5%. We report the first use of EDEG in the isolation of EVs from human bile and the proteomic analysis of human bile-derived EV-proteins in CCA. Claudin-3 in bile-derived EVs is a useful biomarker for CCA.

Clinical proteomics for prostate cancer: understanding prostate cancer pathology and protein biomarkers for improved disease management

Following the introduction of routine Prostate Specific Antigen (PSA) screening in the early 1990's, Prostate Cancer (PCa) is often detected at an early stage. There are also a growing number of treatment options available and so the associated mortality rate is generally low. However, PCa is an extremely complex and heterogenous disease and many patients suffer disease recurrence following initial therapy. Disease recurrence commonly results in metastasis and metastatic PCa has an average survival rate of just 3-5 years. A significant problem in the clinical management of PCa is being able to differentiate between patients who will respond to standard therapies and those who may benefit from more aggressive intervention at an earlier stage. It is also acknowledged that for many men the disease is not life threatenting. Hence, there is a growing desire to identify patients who can be spared the significant side effects associated with PCa treatment until such time (if ever) their disease progresses to the point where treatment is required. To these important clinical needs, current biomarkers and clinical methods for patient stratification and personlised treatment are insufficient. This review provides a comprehensive overview of the complexities of PCa pathology and disease management. In this context it is possible to review current biomarkers and proteomic technologies that will support development of biomarker-driven decision tools to meet current important clinical needs. With such an in-depth understanding of disease pathology, the development of novel clinical biomarkers can proceed in an efficient and effective manner, such that they have a better chance of improving patient outcomes.

The Role of Exosomes in Stemness and Neurodegenerative Diseases-Chemoresistant-Cancer Therapeutics and Phytochemicals

Exosomes exhibit a wide range of biological properties and functions in the living organisms. They are nanometric vehicles and used for delivering drugs, as they are biocompatible and minimally immunogenic. Exosomal secretions derived from cancer cells contribute to metastasis, immortality, angiogenesis, tissue invasion, stemness and chemo/radio-resistance. Exosome-derived microRNAs (miRNAs) and long non-coding RNAs (lnc RNAs) are involved in the pathophysiology of cancers and neurodegenerative diseases. For instance, exosomes derived from mesenchymal stromal cells, astrocytes, macrophages, and acute myeloid leukemia (AML) cells are involved in the cancer progression and stemness as they induce chemotherapeutic drug resistance in several cancer cells. This review covered the recent research advances in understanding the role of exosomes in cancer progression, metastasis, angiogenesis, stemness and drug resistance by illustrating the modulatory effects of exosomal cargo (ex. miRNA, lncRNAs, etc.) on cell signaling pathways involved in cancer progression and cancer stem cell growth and development. Recent reports have implicated exosomes even in the treatment of several cancers. For instance, exosomes-loaded with novel anti-cancer drugs such as phytochemicals, tumor-targeting proteins, anticancer peptides, nucleic acids are known to interfere with drug resistance pathways in several cancer cell lines. In addition, this review depicted the need to develop exosome-based novel diagnostic biomarkers for early detection of cancers and neurodegenerative disease. Furthermore, the role of exosomes in stroke and oxidative stress-mediated neurodegenerative diseases including Alzheimer’s disease (AD), and Parkinson’s disease (PD) is also discussed in this article.

Challenges and Opportunities in Clinical Applications of Blood-Based Proteomics in Cancer

Simple Summary

The traditional approach in identifying cancer related protein biomarkers has focused on evaluation of a single peptide/protein in tissue or circulation. At best, this approach has had limited success for clinical applications, since multiple pathological tumor pathways may be involved during initiation or progression of cancer which diminishes the significance of a single candidate protein/peptide. Emerging sensitive proteomic based technologies like liquid chromatography mass spectrometry (LC-MS)-based quantitative proteomics can provide a platform for evaluating serial serum or plasma samples to interrogate secreted products of tumor–host interactions, thereby revealing a more “complete” repertoire of biological variables encompassing heterogeneous tumor biology. However, several challenges need to be met for successful application of serum/plasma based proteomics. These include uniform pre-analyte processing of specimens, sensitive and specific proteomic analytical platforms and adequate attention to study design during discovery phase followed by validation of discovery-level signatures for prognostic, predictive, and diagnostic cancer biomarker applications.

Abstract

Blood is a readily accessible biofluid containing a plethora of important proteins, nucleic acids, and metabolites that can be used as clinical diagnostic tools in diseases, including cancer. Like the on-going efforts for cancer biomarker discovery using the liquid biopsy detection of circulating cell-free and cell-based tumor nucleic acids, the circulatory proteome has been underexplored for clinical cancer biomarker applications. A comprehensive proteome analysis of human serum/plasma with high-quality data and compelling interpretation can potentially provide opportunities for understanding disease mechanisms, although several challenges will have to be met. Serum/plasma proteome biomarkers are present in very low abundance, and there is high complexity involved due to the heterogeneity of cancers, for which there is a compelling need to develop sensitive and specific proteomic technologies and analytical platforms. To date, liquid chromatography mass spectrometry (LC-MS)-based quantitative proteomics has been a dominant analytical workflow to discover new potential cancer biomarkers in serum/plasma. This review will summarize the opportunities of serum proteomics for clinical applications; the challenges in the discovery of novel biomarkers in serum/plasma; and current proteomic strategies in cancer research for the application of serum/plasma proteomics for clinical prognostic, predictive, and diagnostic applications, as well as for monitoring minimal residual disease after treatments. We will highlight some of the recent advances in MS-based proteomics technologies with appropriate sample collection, processing uniformity, study design, and data analysis, focusing on how these integrated workflows can identify novel potential cancer biomarkers for clinical applications.

Prostate cancer-derived exosomes promote osteoblast differentiation and activity through phospholipase D2

Prostate cancer (PCa) is the most frequent cancer in men aged 65 and over. PCa mainly metastasizes in the bone, forming osteosclerotic lesions, inducing pain, fractures, and nerve compression. Cancer cell-derived exosomes participate in the metastatic spread, ranging from oncogenic reprogramming to the formation of pre-metastatic niches. Moreover, exosomes were recently involved in the dialog between PCa cells and the bone metastasis microenvironment. Phospholipase D (PLD) isoforms PLD1/2 catalyze the hydrolysis of phosphatidylcholine to yield phosphatidic acid (PA), regulating tumor progression and metastasis. PLD is suspected to play a role in exosomes biogenesis. We aimed to determine whether PCa-derived exosomes, through PLD, interact with the bone microenvironment, especially osteoblasts, during the metastatic process. Here we demonstrate for the first time that PLD2 is present in exosomes of C4-2B and PC-3 cells. C4-2B-derived exosomes activate proliferation and differentiation of osteoblasts models, by stimulating ERK 1/2 phosphorylation, by increasing the tissue-nonspecific alkaline phosphatase activity and the expression of osteogenic differentiation markers. Contrariwise, when C4-2B exosomes are generated in the presence of halopemide, a PLD pan-inhibitor, they lose their ability to stimulate osteoblasts. Furthermore, the number of released exosomes diminishes significantly (-40%). When the PLD product PA is combined with halopemide, exosome secretion is fully restored. Taken together, our results indicate that PLD2 stimulates exosome secretion in PCa cell models as well as their ability to increase osteoblast activity. Thus, PLD2 could be considered as a potent player in the establishment of PCa bone metastasis acting through tumor cell derived-exosomes.

Inter-Laboratory Comparison of Extracellular Vesicle Isolation Based on Ultracentrifugation

Background/Aims

Extracellular vesicles (EVs), including microvesicles and exosomes, deliver bioactive cargo mediating intercellular communication in physiological and pathological conditions. EVs are increasingly investigated as therapeutic agents and targets, but also as disease biomarkers. However, a definite consensus regarding EV isolation methods is lacking, which makes it intricate to standardize research practices and eventually reach a desirable level of data comparability. In our study, we performed an inter-laboratory comparison of EV isolation based on a differential ultracentrifugation protocol carried out in 4 laboratories in 2 independent rounds of isolation.

Methods

Conditioned medium of colorectal cancer cells was prepared and pooled by 1 person and distributed to each of the participating laboratories for isolation according to a pre-defined protocol. After EV isolation in each laboratory, quantification and characterization of isolated EVs was collectively done by 1 person having the highest expertise in the respective test method: Western blot, flow cytometry (fluorescence-activated cell sorting [FACS], nanoparticle tracking analysis (NTA), and transmission electron microscopy (TEM).

Results

EVs were visualized with TEM, presenting similar cup-shaped and spherical morphology and sizes ranging from 30 to 150 nm. NTA results showed similar size ranges of particles in both isolation rounds. EV preparations showed high purity by the expression of EV marker proteins CD9, CD63, CD81, Alix, and TSG101, and the lack of calnexin. FACS analysis of EVs revealed intense staining for CD63 and CD81 but lower levels for CD9 and TSG101. Preparations from 1 laboratory presented significantly lower particle numbers (p < 0.0001), most probably related to increased processing time. However, even when standardizing processing time, particle yields still differed significantly between groups, indicating inter-laboratory differences in the efficiency of EV isolation. Importantly, no relation was observed between centrifugation speed/k-factor and EV yield.

Conclusions

Our findings demonstrate that quantitative differences in EV yield might be due to equipment- and operator-dependent technical variability in ultracentrifugation-based EV isolation. Furthermore, our study emphasizes the need to standardize technical parameters such as the exact run speed and k-factor in order to transfer protocols between different laboratories. This hints at substantial inter-laboratory biases that should be assessed in multi-centric studies.

Biomarkers That Differentiate Benign Prostatic Hyperplasia from Prostate Cancer: A Literature Review

Prediction of prostate cancer in primary care is typically based upon serum total prostate-specific antigen (tPSA) and digital rectal examination results. However, these tests lack sensitivity and specificity, leading to over-diagnosis of disease and unnecessary, invasive biopsies. Therefore, there is a clinical need for diagnostic tests that can differentiate between benign conditions and early-stage malignant disease in the prostate. In this review, we evaluate research papers published from 2009 to 2019 reporting biomarkers that identified or differentiated benign prostatic hyperplasia (BPH) from prostate cancer. Our review identifies hundreds of potential biomarkers in urine, serum, tissue, and semen proposed as useful targets for differentiating between prostate cancer and BPH patients. However, it is still not apparent which of these candidate biomarkers are most useful, and many will not progress beyond the discovery stage unless they are properly validated for clinical practice. We conclude that this validation will come through the use of multivariate panels which can assess the value of biomarker candidates in combination with clinical parameters as part of a risk prediction calculator. Implementation of such a model will help clinicians stratify patients with prostate cancer symptoms in primary care, with tangible benefits for both the patient and the health service.

Phosphodiesterase SMPDL3B Gene Expression as Independent Outcome Prediction Marker in Localized Prostate Cancer

Current outcome prediction markers for localized prostate cancer (PCa) are insufficient. The impact of the lipid-modifying Sphingomyelin Phosphodiesterase Acid Like 3B (SMPDL3B) in PCa is unknown. Two cohorts of patients with PCa who underwent radical prostatectomy (n = 40, n = 56) and benign prostate hyperplasia (BPH) controls (n = 8, n = 11) were profiled for SMPDL3B expression with qRT-PCR. Publicly available PCa cohorts (Memorial Sloane Kettering Cancer Centre (MSKCC; n = 131, n = 29 controls) and The Cancer Genome Atlas (TCGA; n = 497, n = 53 controls)) served for validation. SMPDL3B's impact on proliferation and migration was analyzed in PC3 cells by siRNA knockdown. In both cohorts, a Gleason score and T stage independent significant overexpression of SMPDL3B was seen in PCa compared to BPH (p < 0.001 each). A lower expression of SMPDL3B was associated with a shorter overall survival (OS) (p = 0.005) in long term follow-up. A SMPDL3B overexpression in PCa tissue was confirmed in the validation cohorts (p < 0.001 each). In the TCGA patients with low SMPDL3B expression, biochemical recurrence-free survival (p = 0.011) and progression-free interval (p < 0.001) were shorter. Knockdown of SMPDL3B impaired PC3 cell migration but not proliferation (p = 0.0081). In summary, SMPLD3B is highly overexpressed in PCa tissue, is inversely associated with localized PCa prognosis, and impairs PCa cell migration.

Claudin-9 enhances the metastatic potential of hepatocytes via Tyk2/Stat3 signaling

BACKGROUND/AIMS

We have previously identified a tight junction protein claudin-9 (CLDN9) as an upregulated gene in hepatocellular carcinoma (HCC) through an immunohistochemistry analysis. Here, we explore its function and clinical relevance in human HCC.

MATERIALS AND METHODS

Stable transfection of the hepatocyte line HL7702 with CLDN9 was confirmed by the real-time polymerase chain reaction (PCR), western blotting, and immunofluorescence. The impact of CLDN9 on the cell invasion and migration was assessed in vitro by a transwell assay and wound-healing experiment. Western blotting was used to determine the activation state of the Tyk2 (tyrosine kinase 2)/Stat3 (signal transducer and activator of transcription 3) pathway. Moreover, we used a Tyk2-RNAi assay to silence the expression of Tyk2 in CLDN9 expressing hepatocytes; subsequently, the impact of the Tyk2/Stat3 signaling pathway on the cell invasion and migration in vitro was assessed by a transwell assay and a wound-healing experiment. Furthermore, an immunohistochemistry method was utilized to explore the expression levels of CLDN9 and p-Stat3 in the HCC tissues and histologically non-neoplastic hepatic tissues.

RESULTS

We confirmed that the expression of CLDN9 significantly enhanced the metastatic ability of hepatocytes in vitro, and the activation of the Stat3 pathway by Tyk2 was an important mechanism by which CLDN9 promoted hepatocyte aggressiveness in HCC.

CONCLUSION

As an HCC proto-oncogene, CLDN9 affected the Stat3 signaling pathway via Tyk2 and ultimately enhanced the metastatic ability of hepatocytes.

miR-10a-5p and miR-29b-3p as Extracellular Vesicle-Associated Prostate Cancer Detection Markers

Extracellular vesicles (EVs) are shed by many different cell types. Their nucleic acids content offers new opportunities for biomarker research in different solid tumors. The role of EV RNA in prostate cancer (PCa) is still largely unknown. EVs were isolated from different benign and malignant prostate cell lines and blood plasma from patients with PCa (n = 18) and controls with benign prostatic hyperplasia (BPH) (n = 7). Nanoparticle tracking analysis (NTA), Western blot, electron microscopy, and flow cytometry analysis were used for the characterization of EVs. Non-coding RNA expression profiling of PC3 metastatic PCa cells and their EVs was performed by next generation sequencing (NGS). miRNAs differentially expressed in PC3 EVs were validated with qRT-PCR in EVs derived from additional cell lines and patient plasma and from matched tissue samples. 92 miRNAs were enriched and 48 miRNAs were depleted in PC3 EVs compared to PC3 cells, which could be confirmed by qRT-PCR. miR-99b-5p was significantly higher expressed in malignant compared to benign EVs. Furthermore, expression profiling showed miR-10a-5p (p = 0.018) and miR-29b-3p (p = 0.002), but not miR-99b-5p, to be overexpressed in plasma-derived EVs from patients with PCa compared with controls. In the corresponding tissue samples, no significant differences in the miRNA expression could be observed. We thus propose that EV-associated miR-10a-5p and miR-29b-3p could serve as potential new PCa detection markers.

A review on protein markers of exosome from different bio-resources and the antibodies used for characterization

Exosomes are small membrane vesicles (ranging from 30 nm to 150 nm), secreted by different cell types upon fusion of multivesicular bodies (MVB) to the cell plasma membrane under a variety of normal and pathological conditions. Through transferring their cargos such as proteins, lipids and nucleic acids from donor cells to recipient cells, exosomes play a crucial role in cell-to-cell communication. Due to their presence in most body fluids (such as blood, breast milk, saliva, urine, bile, pancreatic juice, cerebrospinal and peritoneal fluids), and their role in carrying bioactive molecules from the cells of origin, exosomes have attracted great interest in their diagnostic and prognostic value for various diseases and therapeutic approaches. Although a large body of literature has documented the importance of exosomes over the past decade, there is no article systematically summarizing protein markers of exosome from different resources and the antibodies that are suited to characterize exosomes. In this review, we briefly summarize the exosome marker proteins, exosomal biomarkers for different diseases, and the antibodies suitable for different bio-resources exosomes characterization.

A Rich Array of Prostate Cancer Molecular Biomarkers: Opportunities and Challenges

Prostate cancer is the most prevalent non-skin cancer in men and is the leading cause of cancer-related death. Early detection of prostate cancer is largely determined by a widely used prostate specific antigen (PSA) blood test and biopsy is performed for definitive diagnosis. Prostate cancer is asymptomatic in the early stage of the disease, comprises of diverse clinico-pathologic and progression features, and is characterized by a large subset of the indolent cancer type. Therefore, it is critical to develop an individualized approach for early detection, disease stratification (indolent vs. aggressive), and prediction of treatment response for prostate cancer. There has been remarkable progress in prostate cancer biomarker discovery, largely through advancements in genomic technologies. A rich array of prostate cancer diagnostic and prognostic tests has emerged for serum (4K, phi), urine (Progensa, T2-ERG, ExoDx, SelectMDx), and tumor tissue (ConfirmMDx, Prolaris, Oncoytype DX, Decipher). The development of these assays has created new opportunities for improving prostate cancer diagnosis, prognosis, and treatment decisions. While opening exciting opportunities, these developments also pose unique challenges in terms of selecting and incorporating these assays into the continuum of prostate cancer patient care.

Extracellular Vesicle Integrins Distinguish Unique Cancers

The proteomic profile of extracellular vesicles (EVs) has been of increasing interest, particularly in understanding cancer growth, drug resistance, and metastatic behavior. Emerging data suggest that cancer-derived EVs carry an array of oncogenic cargo, including certain integrin proteins that may, in turn, promote cell detachment, migration, and selection of future metastatic sites. We previously reported a large comparison of secreted vesicle protein cargo across sixty diverse human cancer cell lines. Here, we analyze the distinct integrin profiles of these cancer EVs. We further demonstrate the enrichment of integrin receptors in cancer EVs compared to vesicles secreted from benign epithelial cells. The total EV integrin levels, including the quantity of integrins α6, αv, and β1 correlate with tumor stage across a variety of epithelial cancer cells. In particular, integrin α6 also largely reflects breast and ovarian progenitor cell expression, highlighting the utility of this integrin protein as a potential circulating biomarker of certain primary tumors. This study provides preliminary evidence of the value of vesicle-associated integrin proteins in detecting the presence of cancer cells and prediction of tumor stage. Differential expression of integrins across cancer cells and selective packaging of integrins into EVs may contribute to further understanding the development and progression of tumor growth and metastasis across a variety of cancer types.

Research status and progress of the RNA or protein biomarkers for prostate cancer

Prostate cancer is a kind of male malignancy. Recently, a large number of studies have reported many potential biomarkers for the diagnosis and prognosis of prostate cancer. In this literature review, we have collected a number of potential biomarkers for prostate cancer reported in the last 5 years. Among them, some are undergoing Phase III clinical trials, and others have been approved by the US Food and Drug Administration. However, most are still in the period of basic research. The review will contribute to future research to find the biomarkers to guide clinicians to make personalized treatment decisions for each prostate cancer patient.

Spondyloarthritis patients with and without intestinal symptoms - searching for discriminating biomarkers

Spondyloarthritis (SpA) is often complicated with subclinical gut inflammation. This study was aimed at searching for biomarkers discriminating SpA patients with and without intestinal symptoms. A group of 29 SpA patients and 33 healthy volunteers (control) were included in the study. Based on clinical evaluation, the patient cohort was subdivided into two groups: 1) SpA accompanied by various intestinal symptoms suggesting gut inflammation (group 2, n = 14) and 2) without such complications (group 1, n = 15). Serum concentrations of interleukins (IL) (IL-10, IL-17A/F, IL-22, IL-23), tumour necrosis factor (TNF), bone-homeostasis-related factors (osteoprotegerin – OPG and Dickkopf-1 – DKK-1), and the concentrations of selected gut inflammation-associated factors (intestinal fatty acid binding protein – iFABP, claudin 3 – CLDN3 and calprotectin) in samples of sera and/or urine or stool, respectively, were measured by specific ELISA. Serum concentrations of tested factors were similar in SpA patients and control. Faecal calprotectin level was higher in patients but did not discriminate between group 1 and 2. Compared to group 1, group 2 was characterized by elevated erythrocyte sedimentation rate (ESR), higher serum CLDN3 and DKK-1 levels. In SpA patients, serum DKK-1 concentrations correlated with systemic inflammation markers (R = 0.6, p < 0.01), while serum CLDN3 was found to be an independent risk factor (OR = 4.5, p = 0.021) for the occurrence of intestinal symptoms. We conclude that in SpA patients, up-regulated circulating levels of CLDN3 seem to be related to intestinal complication, while the quantity of circulating DKK-1 reflects the intensity of systemic inflammation.

Increased expression of claudin-17 promotes a malignant phenotype in hepatocyte via Tyk2/Stat3 signaling and is associated with poor prognosis in patients with hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is the second leading cause of cancer death in Asia; however, the molecular mechanism in its tumorigenesis remains unclear. Abnormal expression of claudins (CLDNs), a family of tight junction (TJ) proteins, plays an important role in the metastatic phenotype of epithelial-derived tumors by affecting tight junction structure, function and related cellular signaling pathways. In a previous study, we used a tissue chip assay to identify CLDN17 as an upregulated gene in HCC. Here we aimed to use molecular biology technology to explore the effect of CLDN17 on the malignant phenotype of HCC and the underlying molecular mechanism, with the objective of identifying a new target for HCC treatment and the control of HCC metastasis.

Method

The expression levels of CLDN17 in HCC tissues and histologically non-neoplastic hepatic tissues were explored by immunohistochemistry. Stable transfection of the hepatocyte line HL7702 with CLDN17 was detected by real-time polymerase chain reaction (PCR), western blotting and immunofluorescence. The impact of CLDN17 on the malignant phenotype of HL7702 cells in vitro was assessed by a Cell Counting Kit-8 (CCK8) assay, a Transwell assay and a wound-healing experiment. Western blotting was utilized to detect the activation state of Tyrosine kinase 2 (Tyk2) / signal transducer and activator of transcription3 (Stat3) pathway. A Tyk2 RNA interference (RNAi) was utilized to determine the impact of the Tyk2/Stat3 signaling pathway on the malignant phenotype of hepatocytes.

Results

In this work, our research group first found that CLDN17 was highly expressed in HCC tissues and was associated with poor prognosis. In addition, we demonstrated that CLDN17 affected the Stat3 signaling pathway via Tyk2 and ultimately enhanced the migration ability of hepatocytes.

Conclusion

In conclusion, we confirmed that the upregulated expression of CLDN17 significantly enhances the migration ability of hepatocytes in vitro and we found that the activation of the Stat3 pathway by Tyk2 may an important mechanism by which CLDN17 promotes aggressiveness in hepatocytes.

Promise and Implementation of Proteomic Prostate Cancer Biomarkers

Prostate cancer is one of the most commonly diagnosed malignancy and the fifth leading cause of cancer mortality in men. Despite the broad use of prostate-specific antigen test that resulted in an increase in number of diagnosed cases, disease management needs to be improved. Proteomic biomarkers alone and or in combination with clinical and pathological risk calculators are expected to improve on decreasing the unnecessary biopsies, stratify low risk patients, and predict response to treatment. To this end, significant efforts have been undertaken to identify novel biomarkers that can accurately discriminate between indolent and aggressive cancer forms and indicate those men at high risk for developing prostate cancer that require immediate treatment. In the era of “big data” and “personalized medicine” proteomics-based biomarkers hold great promise to provide clinically applicable tools, as proteins regulate all biological functions, and integrate genomic information with the environmental impact. In this review article, we aim to provide a critical assessment of the current proteomics-based biomarkers for prostate cancer and their actual clinical applicability. For that purpose, a systematic review of the literature published within the last 10 years was performed using the Web of Science Database. We specifically discuss the potential and prospects of use for diagnostic, prognostic and predictive proteomics-based biomarkers, including both body fluid- and tissue-based markers.

Cholangiocyte-derived exosomal long noncoding RNA H19 promotes cholestatic liver injury in mouse and humans

Cholestatic liver injury is an important clinical problem with limited understanding of disease pathologies. Exosomes are small extracellular vesicles released by a variety of cells, including cholangiocytes. Exosome-mediated cell-cell communication can modulate various cellular functions by transferring a variety of intracellular components to target cells. Our recent studies indicate that the long noncoding RNA (lncRNA), H19, is mainly expressed in cholangiocytes, and its aberrant expression is associated with significant down-regulation of small heterodimer partner (SHP) in hepatocytes and cholestatic liver injury in multidrug resistance 2 knockout (Mdr2^-/- ) mice. However, how cholangiocyte-derived H19 suppresses SHP in hepatocytes remains unknown. Here, we report that cholangiocyte-derived exosomes mediate transfer of H19 into hepatocytes and promote cholestatic injury. Hepatic H19 level is correlated with severity of cholestatic injury in both fibrotic mouse models, including Mdr2^-/- mice, a well-characterized model of primary sclerosing cholangitis (PSC), or CCl₄ -induced cholestatic liver injury mouse models, and human PSC patients. Moreover, serum exosomal-H19 level is gradually up-regulated during disease progression in Mdr2^-/- mice and patients with cirrhosis. H19-carrying exosomes from the primary cholangiocytes of wild-type (WT) mice suppress SHP expression in hepatocytes, but not the exosomes from the cholangiocytes of H19^-/- mice. Furthermore, overexpression of H19 significantly suppressed SHP expression at both transcriptional and posttranscriptional levels. Importantly, transplant of H19-carrying serum exosomes of old fibrotic Mdr2^-/- mice significantly promoted liver fibrosis (LF) in young Mdr2^-/- mice.

CONCLUSION

Cholangiocyte-derived exosomal-H19 plays a critical role in cholestatic liver injury. Serum exosomal H19 represents a noninvasive biomarker and potential therapeutic target for cholestatic diseases. (Hepatology 2018).

Quantitative Proteomic Analysis Identifies AHNAK (Neuroblast Differentiation-associated Protein AHNAK) as a Novel Candidate Biomarker for Bladder Urothelial Carcinoma Diagnosis by Liquid-based Cytology

Cytological examination of urine is the most widely used noninvasive pathologic screen for bladder urothelial carcinoma (BLCA); however, inadequate diagnostic accuracy remains a major challenge. We performed mass spectrometry-based proteomic analysis of urine samples of ten patients with BLCA and ten paired patients with benign urothelial lesion (BUL) to identify ancillary proteomic markers for use in liquid-based cytology (LBC). A total of 4,839 proteins were identified and 112 proteins were confirmed as expressed at significantly different levels between the two groups. We also performed an independent proteomic profiling of tumor tissue samples where we identified 7,916 proteins of which 758 were differentially expressed. Cross-platform comparisons of these data with comparative mRNA expression profiles from The Cancer Genome Atlas identified four putative candidate proteins, AHNAK, EPPK1, MYH14 and OLFM4. To determine their immunocytochemical expression levels in LBC, we examined protein expression data from The Human Protein Atlas and in-house FFPE samples. We further investigated the expression of the four candidate proteins in urine cytology samples from two independent validation cohorts. These analyses revealed AHNAK as a unique intracellular protein differing in immunohistochemical expression and subcellular localization between tumor and non-tumor cells. In conclusion, this study identified a new biomarker, AHNAK, applicable to discrimination between BLCA and BUL by LBC. To our knowledge, the present study provides the first identification of a clinical biomarker for LBC based on in-depth proteomics.

Exploring Small Extracellular Vesicles for Precision Medicine in Prostate Cancer

Tumor microenvironment constitutes a complex network in which tumor cells communicate among them and with stromal and immune cells. It has been shown that cancer cells are able to exchange genetic materials through small extracellular vesicles (EVs), a heterogeneous group of vesicles with different size and shape, cargo content, and function. The importance to investigate populations of circulating EVs would be of great importance as prostate cancer (PCa) biomarkers. In several neoplasms as well as in PCa, nanometer-sized EVs of endosomal origin are implicated in supporting tumor growth and metastatic spread by both altering local stroma cells and creating a protumor environment that favors the formation of pre-metastatic niches. Several techniques are applicable for the isolation and analysis of PCa-derived small EVs and are illustrated in this article. Due to the high sensitivity and specificity of these techniques, small EVs have become ideal candidates for early diagnosis. Moreover, we discuss the role of small EVs during PCa carcinogenesis, as well as in modulating the development of drug resistance to hormonal therapy and chemotherapy, thus underlining the potential of EV-tailored strategies in PCa patients.

Extracellular Vesicles in Prostate Cancer Carcinogenesis, Diagnosis, and Management

Extracellular vesicles (EVs), especially exosomes, are now well recognized as major ways by which cancer cells interact with each other and stromal cells. The meaningful messages transmitted by the EVs are carried by all components of the EVs, i.e., the membrane lipids and the cargo (DNAs, RNAs, microRNAs, long non-coding RNAs, proteins). They are clearly part of the armed arsenal by which cancer cells obtain and share more and more advantages to grow and conquer new spaces. Identification of these messages offers a significant opportunity to better understand how a cancer occurs and then develops both locally and distantly. But it also provides a powerful means by which cancer progression can be detected and monitored. In the last few years, significant research efforts have been made to precisely identify how the EV trafficking is modified in cancer cells as compared to normal cells and how this trafficking is altered during cancer progression. Prostate cancer has not escaped this trend. The aim of this review is to describe the results obtained when assessing the meaningful content of prostate cancer- and stromal-derived EVs in terms of a better comprehension of the cellular and molecular mechanisms underlying prostate cancer occurrence and development. This review also deals with the use of EVs as powerful tools to diagnose non-indolent prostate cancer as early as possible and to accurately define, in a personalized approach, its present and potential aggressiveness, its response to treatment (androgen deprivation, chemotherapy, radiation, surgery), and the overall patients’ prognosis.

Exosomes in cancer: small vesicular transporters for cancer progression and metastasis, biomarkers in cancer therapeutics

Cancer progression is a polygenic procedure in which the exosomes can function as substantial roles. Exosomes are tiny, phospholipid bilayer membrane nanovesicles of endocytic derivation with a diameter of 40-100 nm. These nanovesicles can transport bioactive molecules containing mRNAs, proteins, DNA fragments, and non-coding RNAs from a donor cell to recipient cells, and cause the alteration in genetic and epigenetic factors and reprogramming of the target cells. Many diverse cell types such as mesenchymal cells, immune cells, and cancer cells can induce the release of exosomes. Increasing evidence illustrated that the exosomes derived from tumor cells might trigger the tumor initiation, tumor cell growth and progression, metastasis, and drug resistance. The secreted nanovesicles of exosomes can play significant roles in cells communicate via shuttling the nucleic acid molecules and proteins to target cells and tissues. In this review, we discussed multiple mechanisms related to biogenesis, load, and shuttle of the exosomes. Also, we illustrated the diverse roles of exosomes in several types of human cancer development, tumor immunology, angiogenesis, and metastasis. The exosomes may act as the promising biomarkers for the prognosis of various types of cancers which suggested a new pathway for anti-tumor therapeutic of these nanovesicles and promoted exosome-based cancer for clinical diagnostic and remedial procedures.

Advances in the Study of Aptamer-Protein Target Identification Using the Chromatographic Approach

Ever since the development of the process known as the systematic evolution of ligands by exponential enrichment (SELEX), aptamers have been widely used in a variety of studies, including the exploration of new diagnostic tools and the discovery of new treatment methods. Aptamers' ability to bind to proteins with high affinity and specificity, often compared to that of antibodies, enables the search for potential cancer biomarkers and helps us understand the mechanisms of carcinogenesis. The blind spot of those investigations is usually the difficulty in the selective extraction of targets attached to the aptamer. There are many studies describing the cell SELEX for the prime choice of aptamers toward living cancer cells or even whole tumors in the animal models. However, a dilemma arises when a large number of proteins are being identified as potential targets, which is often the case. In this article, we present a new analytical approach designed to selectively target proteins bound to aptamers. During studies, we have focused on the unambiguous identification of the molecular targets of aptamers characterized by high specificity to the prostate cancer cells. We have compared four assay approaches using electrophoretic and chromatographic methods for "fishing out" aptamer protein targets followed by mass spectrometry identification. We have established a new methodology, based on the fluorescent-tagged oligonucleotides commonly used for flow-cytometry experiments or as optic aptasensors, that allowed the detection of specific aptamer-protein interactions by mass spectrometry. The use of atto488-labeled aptamers for the tracking of the formation of specific aptamer-target complexes provides the possibility of studying putative protein counterparts without needing to apply enrichment techniques. Significantly, changes in the hydrophobic properties of atto488-labeled aptamer-protein complexes facilitate their separation by reverse-phase chromatography combined with fluorescence detection followed by mass-spectrometry-based protein identification. These comparative results of several methodological approaches confirmed the universal applicability of this method to studying aptamer-protein interactions with high sensitivity, showing superior properties compared with pull-down techniques.

"Exosomics"-A Review of Biophysics, Biology and Biochemistry of Exosomes With a Focus on Human Breast Milk

Exosomes are biomolecular nanostructures released from cells. They carry specific biomolecular information and are mainly researched for their exquisite properties as a biomarker source and delivery system. We introduce exosomes in the context of other extracellular vesicles, describe their biophysical isolation and characterisation and discuss their biochemical profiling. Motivated by our interest in early-life nutrition and health, and corresponding studies enrolling lactating mothers and their infants, we zoom into exosomes derived from human breast milk. We argue that these should be more extensively studied at proteomic and micronutrient profiling level, because breast milk exosomes provide a more specific window into breast milk quality from an immunological (proteomics) and nutritional (micronutrient) perspective. Such enhanced breast milk exosome profiling would thereby complement and enrich the more classical whole breast milk analysis and is expected to deliver more functional insights than the rather descriptive analysis of human milk, or larger fractions thereof, such as milk fat globule membrane. We substantiate our arguments by a bioinformatic analysis of two published proteomic data sets of human breast milk exosomes.

Impact of Phosphoproteomics in the Era of Precision Medicine for Prostate Cancer

Prostate cancer is the most common malignancy in men in the United States. While androgen deprivation therapy results in tumor responses initially, there is relapse and progression to metastatic castration-resistant prostate cancer. Currently, all prostate cancer patients receive essentially the same treatment, and there is a need for clinically applicable technologies to provide predictive biomarkers toward personalized therapies. Genomic analyses of tumors are used for clinical applications, but with a paucity of obvious driver mutations in metastatic castration-resistant prostate cancer, other applications, such as phosphoproteomics, may complement this approach. Immunohistochemistry and reverse phase protein arrays are limited by the availability of reliable antibodies and evaluates a preselected number of targets. Mass spectrometry-based phosphoproteomics has been used to profile tumors consisting of thousands of phosphopeptides from individual patients after surgical resection or at autopsy. However, this approach is time consuming, and while a large number of candidate phosphopeptides are obtained for evaluation, limitations are reduced reproducibility, sensitivity, and precision. Targeted mass spectrometry can help eliminate these limitations and is more cost effective and less time consuming making it a practical platform for future clinical testing. In this review, we discuss the use of phosphoproteomics in prostate cancer and other clinical cancer tissues for target identification, hypothesis testing, and possible patient stratification. We highlight the majority of studies that have used phosphoproteomics in prostate cancer tissues and cell lines and propose ways forward to apply this approach in basic and clinical research. Overall, the implementation of phosphoproteomics via targeted mass spectrometry has tremendous potential to aid in the development of more rational, personalized therapies that will result in increased survival and quality of life enhancement in patients suffering from metastatic castration-resistant prostate cancer.

Claudin-3 Inhibits Lung Squamous Cell Carcinoma Cell Epithelial-mesenchymal Transition and Invasion via Suppression of the Wnt/β-catenin Signaling Pathway

Altered expression of claudin-3 (CLDN3), a key cytoskeletal structural protein of the tight junctions in the epithelium, is associated with the development and metastasis of various human cancers. CLDN3 expression has been shown to be significantly associated with the prognosis of lung squamous cell carcinoma (SqCC). This study investigated the role of CLDN3 in inhibiting lung SqCC cell migration and invasion as well as the underlying molecular mechanisms. The CLDN3 levels were assessed between 20 paired lung SqCC tissues and adjacent normal tissues using quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. The ectopic CLDN3 overexpression or knockdown was generated by using a plasmid carrying CLDN3 cDNA or shRNA, respectively. CLDN3 expression was significantly reduced in lung SqCC tissues vs. the adjacent normal tissues. The ectopic CLDN3 overexpression markedly inhibited the migration, invasion, and epithelial-mesenchymal transition (EMT) of lung cancer H520 cells, whereas CLDN3 knockdown had an inverse effect on SK-MES-1 cells. However, cell viability and plate colony formation assays showed that both CLDN3 knockdown and overexpression did not affect SqCC cell proliferation. Both tissue and cell data revealed that CLDN3 expression was significantly associated with the expression of the EMT biomarkers E-cadherin and Vimentin. Furthermore, CLDN3-modulated EMT and expression of the EMT markers were through regulation of the Wnt/β-catenin signaling pathway. In conclusion, this study identified reduced CLDN3 expression in lung SqCC tissues, which was associated with the progression and metastasis of lung SqCC and was attributed to EMT by activation of the Wnt pathway. Thus, CLDN3 could be further evaluated as a novel biomarker for predicting the prognosis of lung SqCC and as a target for the treatment of lung SqCC in the future.