Circulating exosomal miR-92b: Its role for cancer immunoediting and clinical value for prediction of posttransplant hepatocellular carcinoma recurrence

Cancer exosomes and natural killer cells dysfunction: biological roles, clinical significance and implications for immunotherapy

Tumor-derived exosomes (TDEs) play pivotal roles in several aspects of cancer biology. It is now evident that TDEs also favor tumor growth by negatively affecting anti-tumor immunity. As important sentinels of immune surveillance system, natural killer (NK) cells can recognize malignant cells very early and counteract the tumor development and metastasis without a need for additional activation. Based on this rationale, adoptive transfer of ex vivo expanded NK cells/NK cell lines, such as NK-92 cells, has attracted great attention and is widely studied as a promising immunotherapy for cancer treatment. However, by exploiting various strategies, including secretion of exosomes, cancer cells are able to subvert NK cell responses. This paper reviews the roles of TDEs in cancer-induced NK cells impairments with mechanistic insights. The clinical significance and potential approaches to nullify the effects of TDEs on NK cells in cancer immunotherapy are also discussed.

A Model Based on Artificial Intelligence Algorithm for Monitoring Recurrence of HCC after Hepatectomy

BACKGROUND

There is no satisfactory indicator for monitoring recurrence after resection of hepatocellular carcinoma (HCC). This retrospective study aimed to design and validate an HCC monitor recurrence (HMR) model for patients without metastasis after hepatectomy.

METHODS

A training cohort was recruited from 1179 patients with HCC without metastasis after hepatectomy between February 2012 and December 2015. An HMR model was developed using an AdaBoost classifier algorithm. The factors included patient age, TNM staging, tumor size, and pre/postoperative dynamic variations of alpha-fetoprotein (AFP). The diagnostic efficacy of the model was evaluated based on the area under the receiver operating characteristic curves (AUCs). The model was validated using a cohort of 695 patients.

RESULTS

In preoperative patients with positive or negative AFP, the AUC of the validation cohort in the HMR model was .8877, which indicated better diagnostic efficacy than that of serum AFP (AUC, .7348). The HMR model predicted recurrence earlier than computed tomography/magnetic resonance imaging did by 191.58 ± 165 days. In addition, the HMR model can predict the prognosis of patients with HCC after resection.

CONCLUSIONS

The HMR model established in this study is more accurate than serum AFP for monitoring recurrence after hepatectomy for HCC and can be used for real-time monitoring of the postoperative status in patients with HCC without metastasis.

Roles and mechanisms of exosomal non-coding RNAs in human health and diseases

Exosomes play a role as mediators of cell-to-cell communication, thus exhibiting pleiotropic activities to homeostasis regulation. Exosomal non-coding RNAs (ncRNAs), mainly microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are closely related to a variety of biological and functional aspects of human health. When the exosomal ncRNAs undergo tissue-specific changes due to diverse internal or external disorders, they can cause tissue dysfunction, aging, and diseases. In this review, we comprehensively discuss the underlying regulatory mechanisms of exosomes in human diseases. In addition, we explore the current knowledge on the roles of exosomal miRNAs, lncRNAs, and circRNAs in human health and diseases, including cancers, metabolic diseases, neurodegenerative diseases, cardiovascular diseases, autoimmune diseases, and infectious diseases, to determine their potential implication in biomarker identification and therapeutic exploration.

Tumor-Derived Extracellular Vesicles: Their Role in Immune Cells and Immunotherapy

Nowadays, tumor has been the serious threat to human health and life. To further explore the mechanism of tumor genesis and development is necessarily for developing the effective treatment strategy. Extracellular vesicles are the vesicles secreted by almost all types of cells, and they play an important part in intercellular communication by transporting their cargoes. Immune cells are the vital components of the human defense system, which defense against infection and tumor through cytotoxicity, immune surveillance, and clearance. However, via release tumor-derived extracellular vesicles, tumor could induce immune cells dysfunction to facilitate its proliferation and metastasis. Studies have shown that tumor-derived extracellular vesicles play dual role on immune cells by their specific cargoes. Here, we reviewed the effects of tumor-derived extracellular vesicles on immune cells in recent years and also summarized their research progress in the tumor immunotherapy and diagnosis.

Exosomal non-coding RNAs in Hepatobiliary Cancer: A Rising Star

Hepatobiliary cancers are a heterogeneous group of malignancies with a dismal prognosis. Despite intensive research efforts focused on these tumors, methods for early diagnosis and effective targeted therapies are still lacking. Exosomes, released by most cells, exist in all kinds of body fluids and play an important role in cell-to-cell communication. They are small membranous vesicles containing biological molecules, such as noncoding RNAs (ncRNAs), which are not translated into proteins, but they exert effects on the regulation of gene transcription and translation. There is growing evidence for the essential roles of ncRNAs in exosomes in both physiological and pathological conditions of hepatobiliary cancers. They have been identified as sensitive diagnostic biomarkers as well as potential therapeutic targets. The present review discusses recent findings in the crosstalk between hepatobiliary cancers cells and the surrounding cells of the microenvironment and discuss their potential clinical usage.

Emerging Role of Extracellular Vesicles in Biomarking the Gastrointestinal Diseases

INTRODUCTION

Extracellular vesicles (EVs) play an important role in cell-cell communication and regulation of various cellular functions under physiological and pathophysiological conditions through transferring their cargo to recipient cells. Molecular constituents of EVs are a fingerprinting profile of secreting cells which can be used as promising prognostic, diagnostic, and drug-response biomarkers in clinical settings.

AREAS COVERED

The present study provides a brief introduction about the biology of EVs and reviews methodologies used for EV isolation and characterization as well as high-throughput strategies to analyze EV contents. Furthermore, this review highlights the importance and unique role of EVs in the development and progression of gastrointestinal (GI) diseases, especially GI cancers, and then discusses their potential use, particularly those isolated from body fluids, in diagnosis and prognosis of GI diseases.

EXPERT OPINION

In-depth analysis of EV content can lead to the identification of new potential biomarkers for early diagnosis and prognosis prediction of GI diseases. The use of a more targeted approach by establishing more reproducible and standardized methods to decrease variations and obtain desired EV population as well as revisiting large pools of identified biomarkers and their evaluation in larger patient cohorts can result in the introduction of more reliable biomarkers in clinic.

The Role of Extracellular Vesicles in Disease Progression and Detection of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and one of the leading causes of cancer-related death worldwide. Despite the improvements in surveillance and treatment, the prognosis of HCC remains poor. Extracellular vesicles (EVs) are a heterogeneous group of phospholipid bilayer-enclosed particles circulating in the bloodstream and mediating intercellular communication. Emerging studies have shown that EVs play a crucial role in regulating the proliferation, immune escape, and metastasis of HCC. In addition, because EVs are present in the circulation at relatively early stages of disease, they are getting attention as an attractive biomarker for HCC detection. Over the past decade, dedicated efforts have been made to isolate EVs more efficiently and make them useful tools in different clinical settings. In this review article, we provide an overview of the EVs isolation methods and highlight the role of EVs as mediators in the pathogenesis and progression of HCC. Lastly, we summarize the potential applications of EVs in early-stage HCC detection.

RETRACTED: Hepatocellular carcinoma cells-derived exosomal microRNA-378b enhances hepatocellular carcinoma angiogenesis

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figs. 2D/G/H, 4C, 5F and 6D, which appear to have the same eyebrow shaped phenotype as many other publications tabulated here (https://docs.google.com/spreadsheets/d/149EjFXVxpwkBXYJOnOHb6RhAqT4a2llhj9LM60MBffM/edit#gid=0). The journal requested the corresponding author comment on these concerns and provide the raw data. However the authors were not able to satisfactorily fulfil this request and therefore the Editor-in-Chief decided to retract the article.

Exosomal microRNAs as Biomarkers and Therapeutic Targets for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the second most common cause of cancer-related death globally. This type of liver cancer is frequently detected at a late stage by current biomarkers because of the high clinical and biological heterogeneity of HCC tumours. From a plethora of molecules and cellular compounds, small nanoparticles with an endosomal origin are valuable cancer biomarkers or cargos for novel treatments. Despite their small sizes, in the range of 40–150 nm, these particles are delimited by a lipid bilayer membrane with a specific lipid composition and carry functional information—RNA, proteins, miRNAs, long non-coding RNAs (lncRNAs), or DNA fragments. This review summarizes the role of exosomal microRNA (miRNA) species as biomarkers in HCC therapy. After we briefly introduce the exosome biogenesis and the methods of isolation and characterization, we discuss miRNA’s correlation with the diagnosis and prognosis of HCC, either as single miRNA species, or as specific panels with greater clinical impact. We also review the role of exosomal miRNAs in the tumourigenic process and in the cell communication pathways through the delivery of cargos, including proteins or specific drugs.

Exosomal microRNAs in hepatocellular carcinoma

Hepatocellular carcinoma is one of the most common malignant tumors worldwide and the fourth leading cause of cancer-related deaths. The prognosis of hepatocellular carcinoma patients is extremely poor due to the occult onset and high metastasis of hepatocellular carcinoma. Therefore, biomarkers with high specificity and sensitivity are of great importance in early screening, diagnosis prognosis, and treatment of hepatocellular carcinoma patients. Exosomes are tiny vesicles secreted by various types of cells, which can serve as mediators of intercellular communication to regulate the tumor microenvironment, and play a key role in the occurrence, development, prognosis, monitor and treatment of hepatocellular carcinoma. As microRNA deliverer, exosomes are involved in multiple life activities by regulating target genes of recipient cells such as proliferation, invasion, metastasis and apoptosis of cancer cells. In this review, we summarized the composition, active mechanism and function of exosomal microRNAs in hepatocellular carcinoma, and elaborated on their potential application value of early diagnosis and treatment in hepatocellular carcinoma.

Current perspectives on exosomes in the diagnosis and treatment of hepatocellular carcinoma (review)

The prognosis of hepatocellular carcinoma (HCC), a malignant tumor, is poor. Tumor recurrence and metastasis are the major challenges for the treatment of HCC. Various studies have demonstrated that exosomes, which are loaded with various biomolecules including nucleic acids, lipids, and proteins are involved in the recurrence and metastasis of HCC. Additionally, exosomes mediate various biological processes, such as immune response, cell apoptosis, angiogenesis, thrombosis, autophagy, and intercellular signal transduction. In cancer, exosomes regulate cancer cell differentiation, development, and drug resistance. Circular RNAs, microRNAs, and proteins in the exosomes can serve as early diagnostic and prognostic markers for HCC. As exosomes are characterized by low immunogenicity and high stability in the tissues and circulation, they can be used to deliver the drugs in cancer therapies.

Exosomes in hepatocellular carcinoma microenvironment and their potential clinical application value

Hepatocellular carcinoma (HCC) has become a challenging disease in the world today. Due to the limitations on the current diagnosis and treatment as well as its high metastatic ability and high recurrence rate, HCC gradually becomes the second deadliest tumor. Exosomes are one of the types of cell-derived vesicles and can carry intracellular materials such as genetic materials, lipids, and proteins. In recent years, it has been verified that exosomes are linked to numerous physiological and pathological processes, including HCC. However, how exosomes affect HCC progression remains largely unknown. In this review, the exosome-mediated cellular material transfer between cells of different types in the HCC microenvironment and their effects on the behaviors and functions of recipient cells are studied. Furthermore, we also addressed the underlying molecular mechanisms. We believe that new light on the diagnosis of this cancer as well as its treatment strategies will be shed after a collation of literature in this area.

Exosomal Non-Coding RNAs: Regulatory and Therapeutic Target of Hepatocellular Carcinoma

Exosomes are small extracellular vesicles secreted by most somatic cells, which can carry a variety of biologically active substances to participate in intercellular communication and regulate the pathophysiological process of recipient cells. Recent studies have confirmed that non-coding RNAs (ncRNAs) carried by tumor cell/non-tumor cell-derived exosomes have the function of regulating the cancerous derivation of target cells and remodeling the tumor microenvironment (TME). In addition, due to the unique low immunogenicity and high stability, exosomes can be used as natural vehicles for the delivery of therapeutic ncRNAs in vivo. This article aims to review the potential regulatory mechanism and the therapeutic value of exosomal ncRNAs in hepatocellular carcinoma (HCC), in order to provide promising targets for early diagnosis and precise therapy of HCC.

Detection of circulating tumour cells enables early recurrence prediction in hepatocellular carcinoma patients undergoing liver transplantation

BACKGROUND & AIMS

Liver transplantation (LTx) is one of the most effective treatments for hepatocellular carcinoma (HCC); however, tumour recurrence after LTx often leads to poor outcomes. This study investigated the value of circulating tumour cells (CTCs) as a predictor of recurrence following LTx in patients with HCC.

METHODS

This analysis included 193 patients with HCC who underwent LTx at our institute and accepted pre- and post-operative CTC detection; 38 were selected for serial CTC monitoring. The predictive value of CTCs for tumour recurrence in patients with HCC following LTx was evaluated. Single-cell whole genome sequencing was used to characterize CTCs.

RESULTS

Overall, the CTC burden decreased after LTx (P < .05). Post-operative CTC count ≥ 1 per 5 mL peripheral blood was identified as a potential biomarker for predicting tumour recurrence after LTx, especially in patients with no detectable CTCs prior to LTx and negative tumour serological biomarkers. The predictive value of post-operative CTC count ≥ 1 per 5 mL blood was retained in patients who did not meet the Milan criteria, University of California San Francisco (UCSF) criteria, or Fudan criteria (all P < .05). Furthermore, post-operative serial CTC detection may be useful in post-surgical surveillance for HCC recurrence.

CONCLUSIONS

CTCs may be a useful biomarker to evaluate recurrence risk following LTx in patients with HCC. Evaluation based on CTC detection may enhance the post-transplant management of HCC, and improve the therapeutic efficacy of LTx.

Extracellular Vesicles in Oncology: from Immune Suppression to Immunotherapy

Exosomes are involved in cell-to-cell communication and play a crucial role in cellular physiology. The role of exosomes in cancer has been widely explored. Tumor cells have evolved and adapted to evade the immune response. The study of the immune system's modulations in favor of rogue tumor cells led to the development of a novel immunotherapeutic strategy targeting the immune checkpoint proteins (ICPs). In clinical settings, the response to ICP therapy has been inconsistent and is difficult to predict. Quantitating the targeted ICPs through immunohistochemistry is one approach, but is not pragmatic in a clinical setting and is often not sensitive. Examining the molecules present in bodily fluids to determine ICP treatment response, "liquid biopsy" is a convenient alternative. The term "liquid biopsy" refers to circulating tumor cells (CTCs), extracellular vesicles (EVs), non-coding (nc) RNA, circulating tumor DNA (ctDNA), circulating free DNA (cfDNA), etc. EVs includes exosomes, microvesicles, and oncosomes. Herein, we focus on exosomes isolated from bodily fluids and their use in liquid biopsy. Due to their unique ability to transfer bioactive molecules and perturb the physiology of recipient cells, exosomes have garnered attention for their immune modulation role and as a resource to identify molecules associated with liquid biopsy-based diagnostic methods. In this review, we examine the putative role of exosomes and their cargo in influencing the immune system. We discuss the immune and tumor cells present in the tumor microenvironment (TME), and the exosomes derived from these cells to understand how they participate in creating the immune-suppressive TME. Additionally, use of exosomes in liquid biopsy-based methods to measure the treatment response elicited by immunotherapy is discussed. Finally, we describe how exosomes have been used to develop immune therapies, especially cell-free vaccines, for cancer treatment.

The Application of Exosomal MicroRNAs in the Treatment of Pancreatic Cancer and Its Research Progress

ABSTRACT

Despite great progress in the treatment of pancreatic cancer under the efforts of researchers, the survival time of patients with pancreatic cancer is shorter than that of patients with other cancers. Thus, we have a great need for innovative therapeutic methods, including research and development of new drugs and innovation of administration methods. Exosomes are a type of extracellular vesicles wrapped by a lipid bilayer. Thanks to the low clearance ratio and strong specificity of exosomes in circulation, together with in-depth research on the surface protein of exosomes and a targeted modification method, there is a strong potential to apply exosomes in the transfer and even targeted delivery of chemotherapeutics, RNA, and natural products. Particularly, exosomes carrying microRNA show good application prospects in cancer therapy. This article is intended to summarize the progress of research relating to the treatment of pancreatic cancer via exosomal microRNAs.

Circulating exosomal MicroRNAs: New non-invasive biomarkers of non-communicable disease

Exosomes are vesicles, ranging of 30-150 nm in diameter, which are released by different cell types into the extracellular space. Exosomes are capable of transporting several biomolecules such as proteins, lipids, DNA, mRNA, and non-coding RNA, including microRNAs (miRs). miRs signatures have been linked to the development of non-communicable diseases and their classification into various subtypes and/or stages. Interestingly, the miRs contained in exosomes (exomiRs) are suitable candidates as non-invasive biomarkers due to their stability in body fluids and harsh conditions, as well as they are considered critical players involved in intercellular communication; so that they can be a promising diagnostic tool for several diseases. Besides, exomiRs allow discrimination between different stages of the disease and could be a valuable strategy for the early detection of several pathologies in a non-invasive approach. This review aims to describe exomiRs present in biologic fluids that can be used as a tool for the diagnosis and prognosis of non-communicable diseases such as cancer, cardiovascular, kidney, and neurodegenerative disease.

Extracellular vesicles as biomarkers in liver diseases: A clinician's point of view

Extracellular vesicles are membrane-bound vesicles containing proteins, lipids, RNAs and microRNAs. They can originate from both healthy and stressed cells, and provide a snapshot of the cell of origin in physiological and pathological circumstances. Various processes that may give rise to the release of extracellular vesicles occur in liver diseases, including hepatocyte apoptosis, hepatic stellate cell activation, liver innate immune system activation, systemic inflammation, and organelle dysfunction (mitochondrial dysfunction and endoplasmic reticulum stress). Numerous studies have therefore investigated the potential role of extracellular vesicles as biomarkers in liver diseases. This review provides an overview of the methods that can be used to measure extracellular vesicle concentrations in clinical settings, ranging from plasma preparation to extracellular vesicle measurement techniques, as well as looking at the challenges of using extracellular vesicles as biomarkers. We also provide a comprehensive review of studies that test extracellular vesicles as diagnostic, severity and prognostic biomarkers in various liver diseases, including non-alcoholic and alcoholic steatohepatitis, viral hepatitis B and C infections, cirrhosis, primary liver cancers, primary sclerosing cholangitis and acute liver failure. In particular, extracellular vesicles could be useful tools to evaluate activity and fibrosis in non-alcoholic fatty liver disease, predict risk of hepatitis B virus reactivation, predict complications and mortality in cirrhosis, detect early hepatocellular carcinoma, detect malignant transformation in primary sclerosing cholangitis and predict outcomes in acute liver failure. While most studies draw on data derived from pilot studies, which still require clinical validation, some extracellular vesicle subpopulations have already been evaluated in solid prospective studies.

Isolation and characterization of exosomes for cancer research

Exosomes are a subset of extracellular vesicles that carry specific combinations of proteins, nucleic acids, metabolites, and lipids. Mounting evidence suggests that exosomes participate in intercellular communication and act as important molecular vehicles in the regulation of numerous physiological and pathological processes, including cancer development. Exosomes are released by various cell types under both normal and pathological conditions, and they can be found in multiple bodily fluids. Moreover, exosomes carrying a wide variety of important macromolecules provide a window into altered cellular or tissue states. Their presence in biological fluids renders them an attractive, minimally invasive approach for liquid biopsies with potential biomarkers for cancer diagnosis, prediction, and surveillance. Due to their biocompatibility and low immunogenicity and cytotoxicity, exosomes have potential clinical applications in the development of innovative therapeutic approaches. Here, we summarize recent advances in various technologies for exosome isolation for cancer research. We outline the functions of exosomes in regulating tumor metastasis, drug resistance, and immune modulation in the context of cancer development. Finally, we discuss prospects and challenges for the clinical development of exosome-based liquid biopsies and therapeutics.

EVs as Potential New Therapeutic Tool/Target in Gastrointestinal Cancer and HCC

For more than a decade, extracellular vesicles (EVs) have been in focus of science. Once thought to be an efficient way to eliminate undesirable cell content, EVs are now well-accepted as being an important alternative to cytokines and chemokines in cell-to-cell communication route. With their cargos, mainly consisting of functional proteins, lipids and nucleic acids, they can activate signalling cascades and thus change the phenotype of recipient cells at local and systemic levels. Their substantial role as modulators of various physiological and pathological processes is acknowledged. Importantly, more and more evidence arises that EVs play a pivotal role in many stages of carcinogenesis. Via EV-mediated communication, tumour cells can manipulate cells from host immune system or from the tumour microenvironment, and, ultimately, they promote tumour progression and modulate host immunity towards tumour's favour. Additionally, the role of EVs in modulating resistance to pharmacological and radiological therapy of many cancer types has become evident lately. Our understanding of EV biology and their role in cancer promotion and drug resistance has evolved considerably in recent years. In this review, we specifically discuss the current knowledge on the association between EVs and gastrointestinal (GI) and liver cancers, including their potential for diagnosis and treatment.

Diagnostic performance of blood-based liquid biopsies in hepatocellular carcinoma: A protocol for systematic review and meta-analysis

BACKGROUND

Hepatocellular carcinoma (HCC) is an aggressive cancer associated with poor prognosis. Early diagnosis is crucial to improve its prognosis. Blood-based liquid biopsies are promising methods in detecting HCC. However, their accuracies have not been systematically assessed, so it is essential to conduct a meta-analysis to evaluate the diagnostic performance of blood-based liquid biopsies in detecting HCC.

METHODS

We will search PubMed, EMBASE, Cochrane Library, Web of Science, Medline, China National Knowledge Infrastructure(CNKI) for the relevant studies that assessed the diagnostic performance of blood-based liquid biopsies including circulating tumor cells(CTCs), circulating tumor DNA(ctDNA), and exosomes(EVs) in HCC patients from inception to September 2020. Two researchers will independently extract the data and use Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) to evaluate the quality of included literature. We will also conduct the pool diagnostic value, heterogeneity across studies and reporting bias. All the statistical analysis will be conducted by Stata V.15.0 and Meta-disc V.1.4.

RESULTS

This review will evaluate the pooled diagnostic value of blood-based liquid biopsies in HCC.

CONCLUSION

This review will summarize the current published evidence of blood-based liquid biopsies in diagnosing HCC, which may provide a great opportunity for promotion and application of them.

OPEN SCIENCE FRAMEWORK(OSF) REGISTRATION NUMBER

September 3, 2020. https://osf.io/9n4yz.

Extracellular Vesicles: New Endogenous Shuttles for miRNAs in Cancer Diagnosis and Therapy?

Extracellular Vesicles (EVs) represent a heterogeneous population of membranous cell-derived structures, including cargo-oriented exosomes and microvesicles. EVs are functionally associated with intercellular communication and play an essential role in multiple physiopathological conditions. Shedding of EVs is frequently increased in malignancies and their content, including proteins and nucleic acids, altered during carcinogenesis and cancer progression. EVs-mediated intercellular communication between tumor cells and between tumor and stromal cells can modulate, through cargo miRNA, the survival, progression, and drug resistance in cancer conditions. These consolidated suggestions and EVs’ stability in bodily fluids have led to extensive investigations on the potential employment of circulating EVs-derived miRNAs as tumor biomarkers and potential therapeutic vehicles. In this review, we highlight the current knowledge about circulating EVs-miRNAs in human cancer and the application limits of these tools, discussing their clinical utility and challenges in functions such as in biomarkers and instruments for diagnosis, prognosis, and therapy.

Circulating miR-92b and miR-375 for monitoring the chemoresistance and prognosis of small cell lung cancer

miRNAs have been reported to be stably detectable in plasma and to function as potent biomarkers in multiple cancers. The study aimed to evaluate the expression of candidate circulating miRNAs in patients with small cell lung cancer (SCLC) to identify potential noninvasive biomarkers. The expression of five miRNAs (miR-92b, miR-146a, miR-375, miR-1224, and miR-1246) was significantly upregulated in plasma after chemoresistance induction. Receiver operating characteristic curve (ROC) analysis showed that the area under the curve (AUC) values of miR-92b and miR-375 were 0.766 and 0.791, respectively. The data demonstrated that among the five miRNAs assessed, these two miRNAs had better diagnostic accuracy for monitoring drug resistance. In addition, miR-92b and miR-375 levels were decreased after effective chemotherapy. Furthermore, Kaplan–Meier survival analysis confirmed that high expression of miR-92b and miR-375 was closely related to shorter progression-free survival (PFS) in SCLC patients. In conclusion, these findings indicate that circulating miR-92b and miR-375 might be ideal noninvasive biomarkers for monitoring drug resistance during chemotherapy and evaluating the prognosis of patients with SCLC.

Postoperative circulating tumor cells: An early predictor of extrahepatic metastases in patients with hepatocellular carcinoma undergoing curative surgical resection

BACKGROUND

Postoperative extrahepatic metastases (EHM) contribute to a grim outcome in patients with hepatocellular carcinoma (HCC) who are undergoing curative surgical resection. The current study investigated the clinical value of circulating tumor cells (CTCs) in predicting EHM after curative surgery.

METHODS

A total of 197 patients with HCC who were undergoing curative surgical resection were assigned to a retrospective training cohort (144 patients) or a prospective validation cohort (53 patients). The CELLSEARCH system was used for the detection of CTCs prior to surgical resection and 1 month thereafter. The cutoff value of CTCs was estimated using receiver operating characteristic analysis. Bonferroni correction was applied for multiple testing in a Cox proportional hazards regression model.

RESULTS

In the training cohort, EHM was found to be associated with a higher postoperative CTC burden compared with no EHM (mean: 4.33 vs 0.52; P < .001). Receiver operating characteristic analysis demonstrated a postoperative CTC count ≥3 as the optimal cutoff value for the prediction of EHM. Patients with a postoperative CTC count ≥3 experienced a higher EHM risk (56.3% vs 5.5%) and a shorter median overall survival (31.25 months vs not reached) (all P < .001). The prognostic significance of a postoperative CTC count ≥3 also applied to patient subgroups with a low EHM risk, such as those with an α-fetoprotein level ≤400 ng/mL, absence of vascular invasion, well differentiation, and early tumor stage, and its predictive value was retained in patients with a continuous normal α-fetoprotein level during postoperative follow-up (all P < .05). The results were confirmed in the validation cohort.

CONCLUSIONS

A postoperative CTC count ≥3 appears to be a surrogate marker for the prediction of EHM after curative surgical resection of HCC. More careful surveillance should be recommended to patients with a high CTC load to ensure the greater possibility of early interventions for postoperative EHM.

Role of Molecular Biomarkers in Liver Transplantation for Hepatocellular Carcinoma

Patient selection and organ allocation for liver transplantation (LT) in patients with hepatocellular carcinoma (HCC) relies predominantly on clinical parameters, such as tumor burden (ie, radiological imaging). Patients transplanted within Milan criteria have outstanding outcomes with a 5- and 10-year survival of 70% and 55%, respectively. Tumor recurrence after transplantion is rare in these patients (10%); however, treatment options upon recurrence are generally limited, and outcomes are poor. There are also several studies showing how a subgroup of patients with tumors outside the Milan criteria might achieve comparable outcomes to patients within Milan criteria. In other words, the size and number of tumor nodules does not always reflect tumor biology, which could be better captured using molecular proxies for cancer aggressiveness. Over the last decade, we have significantly improved our understanding of the molecular landscape of early stage HCC. This includes the development of molecular classification, identification of prognostic and mutational signatures, and potential mechanisms of hepatocarcinogenesis. Some molecular markers have already proven useful to predict tumor-related outcomes in HCC patients after LT. Most of these analyses are limited to tissue-derived biomarkers, which limits their implementation in clinical practice because tissue biopsy is not required for HCC diagnosis. Minimally invasive alternative tools, such as liquid biopsy, are being increasingly explored and could help to individualize risk stratification for patients with HCC who will benefit from LT despite being outside the accepted clinical criteria.

The Crosstalk between Tumor Cells and the Microenvironment in Hepatocellular Carcinoma: The Role of Exosomal microRNAs and their Clinical Implications

The communication between hepatocellular carcinoma (HCC) cells and their microenvironment is an essential mechanism supporting or preventing tumor development and progression. Recent evidence has identified extracellular vesicles (EVs) as one of the mechanisms mediating paracrine signaling between cells. Exosomes, the most described class of EVs, deliver proteins, mRNAs, noncoding RNAs, DNA, and lipids to recipient cells, also at remote distances. MicroRNAs (miRNAs), as part of the non-coding RNA exosomal cargo, have an important role in regulating cellular pathways in targeted cells, regulating several processes related to tumor progression invasion and metastasis, such as angiogenesis, immune-escape, epithelial-to-mesenchymal transition, invasion, and multi-drug resistance. Accumulating evidence suggests exosomal miRNAs as relevant players in the dynamic crosstalk among cancerous, immune, and stromal cells in establishing the tumorigenic microenvironment. In addition, they sustain the metastasic niche formation at distant sites. In this review, we summarized the recent findings on the role of the exosome-derived miRNAs in the cross-communication between tumor cells and different hepatic resident cells, with a focus on the molecular mechanisms responsible for the cell re-programming. In addition, we describe the clinical implication derived from the exosomal miRNA-driven immunomodulation to the current immunotherapy strategies and the molecular aspects influencing the resistance to therapeutic agents.

Tumorigenesis, diagnosis, and therapeutic potential of exosomes in liver cancer

Hepatocellular carcinoma (HCC, also called primary liver cancer) is one of the most fatal cancers in the world. Due to the insidiousness of the onset of HCC and the lack of effective treatment methods, the prognosis of HCC is extremely poor, and the 5-year average survival rate is less than 10%. Exosomes are nano-sized microvesicle and contain various components such as nucleic acids, proteins, and lipids. Exosomes are important carriers for signal transmission or transportation of material from cell to cell or between cells and tissues. In recent years, exosomes have been considered as potential therapeutic targets of HCC. A large number of reports indicate that exosomes play a key role in the establishment of an HCC microenvironment, as well as the development, progression, invasion, metastasis, and even the diagnosis, treatment, and prognosis of HCC. However, the exact molecular mechanisms and roles of exosomes in these processes remain unclear. We believe that elucidation of the regulatory mechanism of HCC-related exosomes and its signaling pathway and analysis of its clinical applications in the diagnosis and treatment of HCC can provide useful clues for future treatment regimens for HCC. This article discusses and summarizes the research progress of HCC-related exosomes and their potential clinical applications.

Tumorigenesis, diagnosis, and therapeutic potential of exosomes in liver cancer

Hepatocellular carcinoma (HCC, also called primary liver cancer) is one of the most fatal cancers in the world. Due to the insidiousness of the onset of HCC and the lack of effective treatment methods, the prognosis of HCC is extremely poor, and the 5-year average survival rate is less than 10%. Exosomes are nano-sized microvesicle and contain various components such as nucleic acids, proteins, and lipids. Exosomes are important carriers for signal transmission or transportation of material from cell to cell or between cells and tissues. In recent years, exosomes have been considered as potential therapeutic targets of HCC. A large number of reports indicate that exosomes play a key role in the establishment of an HCC microenvironment, as well as the development, progression, invasion, metastasis, and even the diagnosis, treatment, and prognosis of HCC. However, the exact molecular mechanisms and roles of exosomes in these processes remain unclear. We believe that elucidation of the regulatory mechanism of HCC-related exosomes and its signaling pathway and analysis of its clinical applications in the diagnosis and treatment of HCC can provide useful clues for future treatment regimens for HCC. This article discusses and summarizes the research progress of HCC-related exosomes and their potential clinical applications.

The Role of Exo-miRNAs in Cancer: A Focus on Therapeutic and Diagnostic Applications

Exosomes are extracellular vesicles released into biological fluids where they act as carriers of various molecules, including proteins, lipids, and RNAs, between cells, modulating or perturbing specific physiological processes. Recently, it has been suggested that tumoral cells release excessive amounts of exosomes that, through their cargo, promote tumor progression, stimulating growth, angiogenesis, metastasis, insensitivity to chemotherapy, and immune evasion. Increasing evidence highlights exosomal microRNAs (exo-miRNAs) as important players in tumorigenesis. MicroRNA (miRNA) are a class of small non-coding RNA able to regulate gene expression, targeting multiple mRNAs and inducing translational repression and/or mRNA degradation. Exo-miRNAs are highly stable and easily detectable in biological fluids, and for these reasons, miRNAs are potential cancer biomarkers useful diagnostically and prognostically. Furthermore, since exosomes are natural delivery systems between cells, they can be appropriately modified to carry therapeutic miRNAs to specific recipient cells. Here we summarize the main functions of exo-miRNAs and their possible role for diagnostic and therapeutic applications.