Exosomes derived from HCC cells induce sorafenib resistance in hepatocellular carcinoma both in vivo and in vitro

Sorafenib resistance and therapeutic strategies in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) remains one of the most prevalent and lethal cancers globally. While surgical resection and liver transplantation offer potential cures for early-stage HCC, the majority of patients are diagnosed at advanced stages where such interventions are not viable. Sorafenib, a multi-target kinase inhibitor, has been a cornerstone in the treatment of advanced HCC since its approval in 2007. Despite its significant clinical impact, less than half of the treated patients derive long-term benefits due to the emergence of resistance and associated side effects. This review focuses on the role of sorafenib, an FDA-approved multi-target kinase inhibitor, in treating advanced HCC, discusses the mechanisms underlying its therapeutic effects and associated resistance, and explores additional therapeutic strategies being investigated to improve patient outcomes.

Pathogenesis and Systemic Treatment of Hepatocellular Carcinoma: Current Status and Prospects

Hepatocellular carcinoma (HCC) remains one of the major threats to human health worldwide. The emergence of systemic therapeutic options has greatly improved the prognosis of patients with HCC, particularly those with advanced stages of the disease. In this review, we discussed the pathogenesis of HCC, genetic alterations associated with the development of HCC, and alterations in the tumor immune microenvironment. Then, important indicators and emerging technologies related to the diagnosis of HCC are summarized. Also, we reviewed the major advances in treatments for HCC, offering insights into future prospects for next-generation managements.

Sorafenib enhanced the function of myeloid-derived suppressor cells in hepatocellular carcinoma by facilitating PPARα-mediated fatty acid oxidation

BACKGROUND

Sorafenib, an FDA-approved drug for advanced hepatocellular carcinoma (HCC), faces resistance issues, partly due to myeloid-derived suppressor cells (MDSCs) that enhance immunosuppression in the tumor microenvironment (TME).

METHODS

Various murine HCC cell lines and MDSCs were used in a series of in vitro and in vivo experiments. These included subcutaneous tumor models, cell viability assays, flow cytometry, immunohistochemistry, and RNA sequencing. MDSCs were analyzed for chemotaxis, immunosuppressive functions, fatty acid oxidation (FAO), and PPARα expression. The impact of sorafenib on tumor growth, MDSC infiltration, differentiation, and immunosuppressive function was assessed, alongside the modulation of these processes by PPARα.

RESULTS

Here, we revealed increased infiltration and enhanced function of MDSCs in TME after treatment with sorafenib. Moreover, our results indicated that sorafenib induced the accumulation of MDSCs mediated by CCR2, and pharmacological blockade of CCR2 markedly reduced MDSCs migration and tumor growth. Mechanistically, sorafenib promoted the effect and fatty acid uptake ability of MDSCs and modulated peroxisome proliferator-activated receptor α (PPARα)-mediated fatty acid oxidation (FAO). In addition, tumor-bearing mice fed a high-fat diet (HFD) at the beginning of sorafenib administration had worse outcomes than mice fed a regular diet. Genetic deficiency of PPARα weakens the effect of sorafenib on MDSCs in mice with HCC. Pharmacological inhibition of PPARα has a synergistic anti-tumor effect with sorafenib, which is attenuated by the inhibition of MDSCs. Mechanistically, sorafenib significantly inhibited the differentiation of macrophages by upregulating PPARα expression and suppressing the PU.1-CSF1R pathway.

CONCLUSION

Overall, our study demonstrated that sorafenib enhanced the function of MDSCs by facilitating PPARα-mediated FAO and further augmenting sorafenib resistance, which sheds light on dietary management and improves the therapeutic response in HCC.

The Emerging Role of Long Noncoding RNAs in Sorafenib Resistance Within Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), a liver cancer originating from hepatocytes, is a major health concern and among the most common malignancies worldwide. Sorafenib, approved by the U.S. F.D.A., is the primary first-line treatment for patients with advanced HCC. While the preferred first-line systemic regimen for HCC is immunotherapy with Atezolizumab plus bevacizumab or Tremelimumab-actl + durvalumab, Sorafenib is still an alternative recommended regimen. While some patients with advanced HCC may benefit from Sorafenib treatment, most eventually develop resistance, leading to poor prognosis. Long noncoding RNAs (lncRNAs) have been found to play a critical role in tumorigenesis and the development of HCC, as well as other cancers. They are also key players in tumor drug resistance, though the mechanisms of lncRNAs in Sorafenib resistance in HCC remain poorly understood. This review summarizes the molecular mechanisms contributing to Sorafenib resistance in HCC with their potential correlation with lncRNAs, including the roles of transporters, receptors, cell death regulation, and other influencing factors.

Extracellular vesicles in hepatocellular carcinoma: unraveling immunological mechanisms for enhanced diagnosis and overcoming drug resistance

Current research is focused on utilizing EVs as a biopsy tool to improve the diagnostic accuracy of HCC, reduce surgical risk, and explore their potential in modulating drug resistance and advancing immunotherapeutic strategies. Extracellular vesicles (EVs) have been increasingly recognized as important non-invasive biomarkers in hepatocellular carcinoma (HCC) due to the presence of a variety of biomolecules within them, such as proteins and RNAs, etc. EVs play a key role in the early detection, diagnosis, treatment, and prognostic monitoring of HCC. These vesicles influence the development of HCC and therapeutic response in a variety of ways, including influencing the tumor microenvironment, modulating drug resistance, and participating in immune regulatory mechanisms. In addition, specific molecules such as miRNAs and specific proteins in EVs are regarded as potential markers for monitoring treatment response and recurrence of HCC, which have certain research space and development prospects. In this paper, we summarize the aspects of EVs as HCC diagnostic and drug resistance markers, and also discuss the questions that may be faced in the development of EVs as markers.

Integrating anoikis and ErbB signaling insights with machine learning and single-cell analysis for predicting prognosis and immune-targeted therapy outcomes in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) poses a significant global health challenge due to its poor prognosis and limited therapeutic modalities. Anoikis and ErbB signaling pathways are pivotal in cancer cell proliferation and metastasis, but their relevance in HCC remains insufficiently explored.

Methods

This study evaluates the prognostic significance of anoikis and ErbB signaling pathways in HCC by utilizing data from The Cancer Genome Atlas (TCGA), the International Cancer Genome Consortium (ICGC), three additional independent validation cohorts, and an in-house cohort. Advanced bioinformatics analyses and 167 machine learning models based on leave-one-out cross-validation (LOOCV) were used to predict HCC prognosis and assess outcomes of immune-targeted therapies. Additionally, key biological processes of the anoikis and ErbB signaling pathways in HCC were further investigated.

Results

The single sample Gene Set Enrichment Analysis revealed a strong correlation between upregulated ErbB signaling in high anoikis-expressing tumors and poor clinical outcomes. The development of the Anoikis-ErbB Related Signature (AERS) using the LASSO + RSF model demonstrated robust predictive capabilities, as validated across multiple patient cohorts, and proved effective in predicting responses to immune-targeted therapies. Further investigation highlighted activated NOTCH signaling pathways and decreased macrophage infiltration was associated with resistance to sorafenib and immune checkpoint inhibitors, as evidenced by bulk and single-cell RNA sequencing (scRNA-seq).

Conclusion

AERS provides a novel tool for clinical prognosis and paves the way for immune-targeted therapeutic approaches, underscoring the potential of integrated molecular profiling in enhancing treatment strategies for HCC.

Small-molecule-based targeted therapy in liver cancer

Liver cancer is one of the most prevalent malignant tumors worldwide. According to the Barcelona Clinic Liver Cancer staging criteria, clinical guidelines provide tutorials to clinical management of liver cancer at their individual stages. However, most patients diagnosed with liver cancer are at advanced stage; therefore, many researchers conduct investigations on targeted therapy, aiming to improve the overall survival of these patients. To date, small-molecule-based targeted therapies are highly recommended (first line: sorafenib and lenvatinib; second line: regorafenib and cabozantinib) by current the clinical guidelines of the American Society of Clinical Oncology, European Society for Medical Oncology, and National Comprehensive Cancer Network. Herein, we summarize the small-molecule-based targeted therapies in liver cancer, including the approved and preclinical therapies as well as the therapies under clinical trials, and introduce their history of discovery, clinical trials, indications, and molecular mechanisms. For drug resistance, the revealed mechanisms of action and the combination therapies are also discussed. In fact, the known small-molecule-based therapies still have limited clinical benefits to liver cancer patients. Therefore, we analyze the current status and give our ideas for the urgent issues and future directions in this field, suggesting clues for novel techniques in liver cancer treatment.

Exosomal NAT10 from esophageal squamous cell carcinoma cells modulates macrophage lipid metabolism and polarization through ac4C modification of FASN

N-acetyltransferase 10 (NAT10) is acknowledged as a tumor promoter in various cancers due to its role as a regulator of acetylation modification. Tumor-associated macrophages (TAMs) play a pivotal role in the tumor microenvironment (TME). However, the intercellular communication between esophageal squamous cell carcinoma (ESCC) cells and TAMs involving NAT10 remains poorly understood. This study aimed to elucidate the regulatory mechanism of NAT10 in modulating macrophage lipid metabolism and polarization. Experimental evidence was derived from in vitro and in vivo analyses. We explored the association between upregulated NAT10 in ESCC tissues, macrophage polarization, and the therapeutic efficacy of PD-1. Furthermore, we investigated the impact of methyltransferase 3 (METTL3)-induced m6A modification on the increased expression of NAT10 in ESCC cells. Additionally, we examined the role of exosomal NAT10 in stabilizing the expression of fatty acid synthase (FASN) and promoting macrophage M2 polarization through mediating the ac4C modification of FASN. Results indicated that NAT10, packaged by exosomes derived from ESCC cells, promotes macrophage M2 polarization by facilitating lipid metabolism. In vivo animal studies demonstrated that targeting NAT10 could enhance the therapeutic effect of PD-1 on ESCC by mediating macrophage reprogramming. Our findings offer novel insights into improving ESCC treatment through NAT10 targeting.

Macrophages enhance cisplatin resistance in gastric cancer through the transfer of circTEX2

Cisplatin-based chemotherapy is often used in advanced gastric cancer (GC) treatment, yet resistance to cisplatin may lead to treatment failure. Mechanisms underlying cisplatin resistance remain unclear. Recent evidence highlighted the role of macrophages in cancer chemoresistance. Macrophage-derived exosomes were shown to facilitate intercellular communication. Here, we investigated the cisplatin resistance mechanism based on macrophage-derived exosomes in gastric cancer. Cell growth and apoptosis detection experiments revealed that M2-polarized macrophages increased the resistance of GC cells to cisplatin. qRT-PCR, RNAase R assay, actinomycin D assay and cell nucleo-cytoplasmic separation experiments confirmed the existence of circTEX2 in macrophage cytoplasm, with a higher expression level in M2 macrophages than that in M1 macrophages. Further experiments showed that circTEX2 acted as microRNA sponges for miR-145 and regulated the expression of ATP Binding Cassette Subfamily C Member 1 (ABCC1). Inhibition of the circTEX2/miR-145/ABCC1 axis blocked the cisplatin resistance of gastric cancer induced by M2 macrophages, as evidenced by in vitro and in vivo experiments. In conclusion, our research suggests that the exosomal transfer of M2 macrophage-derived circTEX2 enhances cisplatin resistance in gastric cancer through miR-145/ABCC1. Additionally, communication between macrophages and cancer cells via exosomes may be a promising therapeutic target for the treatment of cisplatin-resistant gastric cancer.

Emerging Roles of Small Extracellular Vesicles in Gastrointestinal Cancer Research and Therapy

Discovered in the late eighties, sEVs are small extracellular nanovesicles (30-150 nm diameter) that gained increasing attention due to their profound roles in cancer, immunology, and therapeutic approaches. They were initially described as cellular waste bins; however, in recent years, sEVs have become known as important mediators of intercellular communication. They are secreted from cells in substantial amounts and exert their influence on recipient cells by signaling through cell surface receptors or transferring cargos, such as proteins, RNAs, miRNAs, or lipids. A key role of sEVs in cancer is immune modulation, as well as pro-invasive signaling and formation of pre-metastatic niches. sEVs are ideal biomarker platforms, and can be engineered as drug carriers or anti-cancer vaccines. Thus, sEVs further provide novel avenues for cancer diagnosis and treatment. This review will focus on the role of sEVs in GI-oncology and delineate their functions in cancer progression, diagnosis, and therapeutic use.

Integrated analysis of tumour-derived exosome-related immune genes to predict progression and immune status of hepatocellular carcinoma

Tumour-derived exosomes (TDEs) play an important role in tumourigenesis and progression by regulating components in the tumour microenvironment (TME), however, the role of TDE-related immune genes in hepatocellular carcinoma is not fully known. We systematically analysed TDE genes from ExoCarta and immune genes from Immport,Machine learning ultimately identified eight TDE-related prognostic immune genes and used them as the basis for constructing a risk model, which was constructed to better predict patients with hepatocellular carcinoma (HCC) compared with published prognostic models. There were significant differences between the high and low risk groups in terms of biological functioning. Low-risk group were more sensitive to immunotherapy, the sensitivity to oxaliplatin and cisplatin differed between the high- and low-risk groups, and knockout of the core gene RAC1 limited the malignant biological behaviour of hepatocellular carcinoma cells. In conclusion, TIRGs are effective in predicting the prognosis of patients with hepatocellular carcinoma and provide a new perspective on immunotherapy and chemotherapy for patients.

Combating drug resistance in hepatocellular carcinoma: No awareness today, no action tomorrow

Hepatocellular carcinoma (HCC), the sixth most common cancer worldwide, is associated with a high degree of malignancy and poor prognosis. Patients with early HCC may benefit from surgical resection to remove tumor tissue and a margin of healthy tissue surrounding it. Unfortunately, most patients with HCC are diagnosed at an advanced or distant stage, at which point resection is not feasible. Systemic therapy is now routinely prescribed to patients with advanced HCC; however, drug resistance has become a major obstacle to the treatment of HCC and exploring purported mechanisms promoting drug resistance remains a challenge. Here, we focus on the determinants of drug resistance from the perspective of non-coding RNAs (ncRNAs), liver cancer stem cells (LCSCs), autophagy, epithelial-mesenchymal transition (EMT), exosomes, ferroptosis, and the tumor microenvironment (TME), with the aim to provide new insights into HCC treatment.

UBE2S promotes malignant properties via VHL/HIF-1α and VHL/JAK2/STAT3 signaling pathways and decreases sensitivity to sorafenib in hepatocellular carcinoma

BACKGROUND

Ubiquitin-conjugating enzyme E2S (UBE2S), an E2 enzyme, is associated with the development of various tumors and exerts oncogenic activities. UBE2S is overexpressed in tumors, including hepatocellular carcinoma (HCC). However, the key molecular mechanisms of UBE2S in HCC still need additional research. The aim of this study was to explore the role of UBE2S in HCC.

METHODS

The expression levels of UBE2S in HCC tissues and cells were detected by western blot analysis, quantitative real-time polymerase chain reaction analysis (qRT-PCR), and immunohistochemistry (IHC). A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, wound healing assay, colony formation assay transwell assay, and animal models were used to detect the proliferation and migration ability of HCC cells. Western blot analysis, qRT-PCR, immunofluorescence, small-interfering RNA (siRNA), and plasmid transfection and coimmunoprecipitation (Co-IP) assays were performed to detect the interaction among UBE2S, von Hippel-Lindau (VHL), hypoxia-inducible factor 1-alpha (HIF-1α), Janus kinase-2 (JAK2), and signal transducer and activator of transcription 3 (STAT3).

RESULTS

In this study, we found that high UBE2S expression was associated with poor prognosis in HCC patients. In addition, UBE2S expression was upregulated in HCC tissues and cell lines. Knockdown of UBE2S inhibited the proliferation and migration of HCC cells in vitro and in vivo by directly interacting with VHL to downregulate the HIF-1α and JAK2/STAT3 signaling pathways. Accordingly, overexpression of UBE2S significantly enhanced the proliferation and migration of HCC cells in vitro via VHL to upregulate HIF-1α and JAK2/STAT3 signaling pathways. Furthermore, we found that downregulation of UBE2S expression enhanced the sensitivity of HCC cells to sorafenib in vivo and in vitro.

CONCLUSION

UBE2S enhances malignant properties via the VHL/HIF-1α and VHL/JAK2/STAT3 signaling pathways and reduces sensitivity to sorafenib in HCC. The findings of this study may open a new approach for HCC diagnosis and provide a potential option for the treatment of HCC.

Intermittent hypoxia BMSCs-derived exosomal miR-31-5p promotes lung adenocarcinoma development via WDR5-induced epithelial mesenchymal transition

BACKGROUND

Intermittent hypoxia (IH) is a factor involved in the incidence and progression of lung adenocarcinoma (LUAD). Bone marrow-derived bone mesenchymal stem cells (BMSCs)-derived exosomes are related to the promotion of tumor development. The objective of this experiment was to clarify the mechanism of exosomes from BMSCs in promoting the progression of LUAD induced by IH.

METHODS

This study examined if IH BMSCS-derived exosomes affect the malignancy of LUAD cells in vitro. Dual-luciferase assays were conducted to confirm the target of miR-31-5p with WD repeat domain 5 (WDR5). We further investigated whether or not  exosomal miR-31-5p or WDR5 could regulate epithelial-mesenchymal transition (EMT). We determined the effect of IH exosomes using a tumorigenesis model in vivo.

RESULTS

miR-31-5p entered into LUAD cells via exosomes. MiR-31-5p was greatly upregulated in IH BMSCs-derived exosomes compared with RA exosomes. Increased expression of exosomal miR-31-5p induced by IH was discovered to target WDR5 directly, increased activation of WDR5, and significantly facilitated EMT, thereby promoting LUAD progression.

CONCLUSIONS

The promoting effect of IH on LUAD is achieved partly through BMSCs-derived exosomal miR-31-5p triggering WDR5 and promoting EMT.

The current status of tumor microenvironment and cancer stem cells in sorafenib resistance of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a heterogeneous and aggressive liver cancer that presents limited treatment options. Despite being the standard therapy for advanced HCC, sorafenib frequently encounters resistance, emphasizing the need to uncover the underlying mechanisms and develop effective treatments. This comprehensive review highlights the crucial interplay between the tumor microenvironment, cancer stem cells (CSCs), and epithelial-mesenchymal transition (EMT) in the context of sorafenib resistance. The tumor microenvironment, encompassing hypoxia, immune cells, stromal cells, and exosomes, exerts a significant impact on HCC progression and therapy response. Hypoxic conditions and immune cell infiltration create an immunosuppressive milieu, shielding tumor cells from immune surveillance and hindering therapeutic efficacy. Additionally, the presence of CSCs emerges as a prominent contributor to sorafenib resistance, with CD133+ CSCs implicated in drug resistance and tumor initiation. Moreover, CSCs undergo EMT, a process intimately linked to tumor progression, CSC activation, and further promotion of sorafenib resistance, metastasis, and tumor-initiating capacity. Elucidating the correlation between the tumor microenvironment, CSCs, and sorafenib resistance holds paramount importance in the quest to develop reliable biomarkers capable of predicting therapeutic response. Novel therapeutic strategies must consider the influence of the tumor microenvironment and CSC activation to effectively overcome sorafenib resistance in HCC.

Research progress of circulating non-coding RNA in diagnosis and treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly malignant tumor that carries a significant risk of morbidity and mortality. This type of cancer is prevalent in Asia due to the widespread presence of risk factors. Unfortunately, HCC often goes undetected until it has reached an advanced stage, making early detection and treatment critical for better outcomes. Alpha-fetoprotein (AFP) is commonly used in clinical practice for diagnosing HCC, but its sensitivity and specificity are limited. While surgery and liver transplantation are the main radical treatments, drug therapy and local interventions are better options for patients with advanced HCC. Accurately assessing treatment efficacy and adjusting plans in a timely manner can significantly improve the prognosis of HCC. Non-coding RNA gene transcription products cannot participate in protein production, but they can regulate gene expression and protein function through the regulation of transcription and translation processes. These non-coding RNAs have been found to be associated with tumor development in various types of tumors. Noncoding RNA released by tumor or blood cells can circulate in the blood and serve as a biomarker for diagnosis, prognosis, and efficacy assessment. This article explores the unique role of circulating noncoding RNA in HCC from various perspectives.

Role of Extracellular Vesicles in Liver Diseases

Extracellular vesicles (EVs) are cell-derived membrane structures that are formed by budding from the plasma membrane or originate from the endosomal system. These microparticles (100 nm-100 µm) or nanoparticles (>100 nm) can transport complex cargos to other cells and, thus, provide communication and intercellular regulation. Various cells, such as hepatocytes, liver sinusoidal endothelial cells (LSECs) or hepatic stellate cells (HSCs), secrete and take up EVs in the healthy liver, and the amount, size and content of these vesicles are markedly altered under pathophysiological conditions. A comprehensive knowledge of the modified EV-related processes is very important, as they are of great value as biomarkers or therapeutic targets. In this review, we summarize the latest knowledge on hepatic EVs and the role they play in the homeostatic processes in the healthy liver. In addition, we discuss the characteristic changes of EVs and their potential exacerbating or ameliorating effects in certain liver diseases, such as non-alcoholic fatty liver disease (NAFLD), alcoholic fatty liver disease (AFLD), drug induced liver injury (DILI), autoimmune hepatitis (AIH), hepatocarcinoma (HCC) and viral hepatitis.

Immunotherapy for hepatocellular carcinoma: Recent advances and future targets

Immunotherapy is a promising approach to treating various types of cancers, including hepatocellular carcinoma (HCC). While single immunotherapy drugs show limited effectiveness on a small subset of patients, the combination of the anti PD-L1 atezolizumab and anti-vascular endothelial growth factor bevacizumab has shown significant improvement in survival compared to sorafenib as a first-line treatment. However, the current treatment options still have a low success rate of about 30%. Thus, more effective treatments for HCC are urgently required. Several novel immunotherapeutic methods, including the use of novel immune checkpoint inhibitors, innovative immune cell therapies like chimeric antigen receptor T cells (CAR-T), TCR gene-modified T cells and stem cells, as well as combination strategies are being tested in clinical trials for the treatment of HCC. However, some crucial issues still exist such as the presence of heterogeneous antigens in solid tumors, the immune-suppressive environment within tumors, the risk of on-target/off-tumor, infiltrating CAR-T cells, immunosuppressive checkpoint molecules, and cytokines. Overall, immunotherapy is on the brink of major advancements in the fight against HCC.

Mechanisms of drug resistance in breast cancer liver metastases: Dilemmas and opportunities

Breast cancer is the leading cause of cancer-related deaths in females worldwide, and the liver is one of the most common sites of distant metastases in breast cancer patients. Patients with breast cancer liver metastases face limited treatment options, and drug resistance is highly prevalent, leading to a poor prognosis and a short survival. Liver metastases respond extremely poorly to immunotherapy and have shown resistance to treatments such as chemotherapy and targeted therapies. Therefore, to develop and to optimize treatment strategies as well as to explore potential therapeutic approaches, it is crucial to understand the mechanisms of drug resistance in breast cancer liver metastases patients. In this review, we summarize recent advances in the research of drug resistance mechanisms in breast cancer liver metastases and discuss their therapeutic potential for improving patient prognoses and outcomes.

Extracellular Vesicles in Cancer Drug Resistance: Implications on Melanoma Therapy

Extracellular vesicles (EVs) are involved in the pathogenesis of neoplastic diseases. Their role in mediating drug resistance has been widely described in several types of cancers, including melanoma. EVs can mediate drug resistance through several different mechanisms, such as drug-sequestration, transfer of pro-survival proteins and RNA, induction of cancer stem cell-like features and interaction with cells of the tumor microenvironment and immune-system. Melanoma is a highly immunogenic tumor originating from the malignant transformation of melanocytes. Several therapeutic strategies currently used in the treatment of melanoma and the combination of BRAF and MEK-inhibitors, as well as immune check-point inhibitors (ICI), have consistently improved the overall survival time of melanoma patients. However, the development of resistance is one of the biggest problems leading to a poor clinical outcome, and EVs can contribute to this. EVs isolated from melanoma cells can contain "sequestered" chemotherapeutic drugs in order to eliminate them, or bioactive molecules (such as miRNA or proteins) that have been proven to play a crucial role in the transmission of resistance to sensitive neoplastic cells. This leads to the hypothesis that EVs could be considered as resistance-mediators in sensitive melanoma cells. These findings are a pivotal starting point for further investigations to better understand EVs' role in drug resistance mechanisms and how to target them. The purpose of this review is to summarize knowledge about EVs in order to develop a deeper understanding of their underlying mechanisms. This could lead to the development of new therapeutic strategies able to bypass EV-mediated drug-resistance in melanoma, such as by the use of combination therapy, including EV release inhibitors.

α2,6-Sialylation promotes hepatocellular carcinoma cells migration and invasion via enhancement of nSmase2-mediated exosomal miRNA sorting

Exosomes have a critical role in the intercellular communication and metastatic progression of hepatocellular carcinoma (HCC). Recently, our group showed that α2, 6-sialylation played an important role in the proliferation- and migration-promoting effects of cancer-derived exosomes. However, the molecular basis remains elusive. In this study, the mechanism of α2, 6-sialylation-mediated specific microRNAs (miRNA) sorting into exosomes was illustrated. We performed miRNA profiling analysis to compare exosomes from HCC cell lines that differ only in α2, 6-sialylation status. A total of 388 differentially distributed miRNAs were identified in wild-type and β-galactoside α2, 6-sialyltransferase I (ST6Gal-I) knockdown MHCC-97H cells-derived exosomes. Neutral sphingomyelinase-2 (nSmase2), an important regulator mediating the sorting of exosomal miRNAs, was found to be a target of ST6Gal-I. The reduction of α2, 6-sialylation could impair the activity of nSmase2, as well as the nSmase2-dependent exosomal miRNAs sorting. This α2,6-sialylation-dependent sorting exerted an augmentation of motility on recipient HCC cells. Our data further demonstrated that α2,6-sialylation-mediated sorting of exosomal miR-100-5p promoted the migration and invasion of recipient HepG2 cells via the PI3K/AKT signaling pathway. The cellular metastasis-related gene CLDN11 was confirmed as a direct target of exosomal miR-100-5p, which elevated the mobility of recipient HCC cells. In conclusion, our results showed that α2,6-sialylation modulates nSmase2-dependent exosomal miRNAs sorting and promotes HCC progression.

Role of exosomes in hepatocellular carcinoma and the regulation of traditional Chinese medicine

Hepatocellular carcinoma (HCC) usually occurs on the basis of chronic liver inflammatory diseases and cirrhosis. The liver microenvironment plays a vital role in the tumor initiation and progression. Exosomes, which are nanometer-sized membrane vesicles are secreted by a number of cell types. Exosomes carry multiple proteins, DNAs and various forms of RNA, and are mediators of cell-cell communication and regulate the tumor microenvironment. In the recent decade, many studies have demonstrated that exosomes are involved in the communication between HCC cells and the stromal cells, including endothelial cells, macrophages, hepatic stellate cells and the immune cells, and serve as a regulator in the tumor proliferation and metastasis, immune evasion and immunotherapy. In addition, exosomes can also be used for the diagnosis and treatment HCC. They can potentially serve as specific biomarkers for early diagnosis and drug delivery vehicles of HCC. Chinese herbal medicine, which is widely used in the prevention and treatment of HCC in China, may regulate the release of exosomes and exosomes-mediated intercellular communication. In this review, we summarized the latest progresses on the role of the exosomes in the initiation, progression and treatment of HCC and the potential value of Traditional Chinese medicine in exosomes-mediated biological behaviors of HCC.

Extracellular Vesicles and Fatty Liver

Fatty liver is a complex pathological process caused by multiple etiologies. In recent years, the incidence of fatty liver has been increasing year by year, and it has developed into a common chronic disease that seriously affects people's health around the world. It is an important risk factor for liver cirrhosis, liver cancer, and a variety of extrahepatic chronic diseases. Therefore, the early diagnosis and early therapy of fatty liver are important. Except for invasive liver biopsy, there is still a lack of reliable diagnosis and staging methods. Extracellular vesicles are small double-layer lipid membrane vesicles derived from most types of cells. They play an important role in intercellular communication and participate in the occurrence and development of many diseases. Since extracellular vesicles can carry a variety of biologically active substances after they are released by cells, they have received widespread attention. The occurrence and development of fatty liver are also closely related to extracellular vesicles. In addition, extracellular vesicles are expected to provide a new direction for the diagnosis of fatty liver. This article reviews the relationship between extracellular vesicles and fatty liver, laying a theoretical foundation for the development of new strategies for the diagnosis and therapy of fatty liver.

A new integrated method for tissue extracellular vesicle enrichment and proteome profiling

Extracellular vesicles (EVs) are membranous vesicles released by cells that carry a number of biologically important components such as lipids, proteins, and mRNAs. EVs can mediate cancer cell migration, invasion, angiogenesis, and cell survival, greatly contributing to cell-to-cell communication in the tumor microenvironment. Additionally, EVs have been found to have diagnostic and prognostic significance in various cancers. However, the direct isolation of pure EVs remains challenging, especially from tissue samples. Currently available EV isolation approaches, e.g., ultracentrifugation, are time-consuming, instrumental dependent, and have a low recovery rate with limited purity. It is urgent to develop rapid and efficient methods for enriching tissue EVs for biological and clinical studies. Here, we developed a novel isolation approach for tissue EVs using an extraction kit combined with TiO2 microspheres (kit-TiO2). The EVs were first precipitated from the tissue fluid using a precipitation agent and then further enriched using microspheres based on the specific interaction between TiO2 and the phosphate groups on the lipid bilayer of the EVs. Kit-TiO2 approach led to improved purity and enrichment efficiency of the isolated EVs, as demonstrated by western blot and proteomic analysis, compared with previously reported methods. A total of 1966 protein groups were identified from the tissue EVs. We compared the proteomic profiles of the liver tissue EVs from healthy and hepatocellular carcinoma (HCC) bearing-mice. Twenty-five significantly upregulated and 75 downregulated protein groups were found in the HCC EVs. Among the differentially expressed proteins, Atic, Copa, Cont3, Me1, Anxa3, Fth1, Anxa5, Phb1, Acaa2, ATPD, and Glud1 were reported to be highly relevant to HCC. This novel isolation strategy has provided a powerful tool for enriching EVs directly from tissues, and may be applied in biomarker discovery and drug screening of HCC.

Therapy-induced modulation of extracellular vesicles in hepatocellular carcinoma

Despite rapid development of anti-tumorigenic treatments, the clinical outcome for hepatocellular carcinoma (HCC) is still far from satisfactory. With a deeper understanding about tumor microenvironment (TME), the critical role of extracellular vesicles (EVs) as intercellular liaison has come into spotlight. The dynamic functionality of these nanoparticles revealed cancer cells can employ both tumor and non-tumorous components for their own benefit, so as to mediate cell-to-cell communication and interchange of oncogenic biomolecules. Increasing studies on HCC-derived EVs have identified various irregulated biomolecules, that may serve as biomarkers or therapeutic targets. In this review, we first introduce the current knowledge about EVs and how they operate to maintain a healthy liver microenvironment. We then summarize some of the aberrant observations reported on HCC-derived EVs and how they contribute to HCC pathogenesis. Finally, we describe how current treatments for HCC alter behavior of EVs, which may shed light for potential prognostic markers and therapeutic strategies.

H-TEX-mediated signaling between hepatocellular carcinoma cells and macrophages and exosome-targeted therapy for hepatocellular carcinoma

There is increasing evidence for the key role of the immune microenvironment in the occurrence and development of hepatocellular carcinoma. As an important component of the immune microenvironment, the polarization state and function of macrophages determine the maintenance of the immunosuppressive tumor microenvironment. Hepatocellular carcinoma tumor-derived exosomes, as information carriers, regulate the physiological state of cells in the microenvironment and control cancer progression. In this review, we focus on the role of the exosome content in disease outcomes at different stages in the progression of hepatitis B virus/hepatitis C virus-induced hepatocellular carcinoma. We also explore the mechanism by which macrophages contribute to the formation of hepatocellular carcinoma and summarize the regulation of macrophage functions by the heterogeneity of exosome loading in liver cancer. Finally, with the rise of exosome modification in immunotherapy research on hepatocellular carcinoma, we summarize the application prospects of exosome-based targeted drug delivery.

The Role of Extracellular Vesicles in Liver Pathogenesis

Extracellular vesicles (EVs) are generated by cells in the form of exosomes, microvesicles, and apoptotic bodies. They can be taken up by neighboring cells, and their contents can have functional impact on the cells that engulf them. As the mediators of intercellular communication, EVs can play important roles in both physiological and pathologic contexts. In addition, early detection of EVs in different body fluids may offer a sensitive diagnostic tool for certain diseases, such as cancer. Furthermore, targeting specific EVs may also become a promising therapeutic approach. This review summarizes the latest findings of EVs in the field of liver research, with a focus on the different contents of the EVs and their impact on liver function and on the development of inflammation, fibrosis, and tumor in the liver. The goal of this review is to provide a succinct account of the various molecules that can mediate the function of EVs so the readers may apply this knowledge to their own research.

Nucleic acids and proteins carried by exosomes from various sources: Potential role in liver diseases

Exosomes are extracellular membrane-encapsulated vesicles that are released into the extracellular space or biological fluids by many cell types through exocytosis. As a newly identified form of intercellular signal communication, exosomes mediate various pathological and physiological processes by exchanging various active substances between cells. The incidence and mortality of liver diseases is increasing worldwide. Therefore, we reviewed recent studies evaluating the role of exosomes from various sources in the diagnosis and treatment of liver diseases.

miR-200c-3p, miR-222-5p, and miR-512-3p Constitute a Biomarker Signature of Sorafenib Effectiveness in Advanced Hepatocellular Carcinoma

Background: Sorafenib constitutes a suitable treatment alternative for patients with advanced hepatocellular carcinoma (HCC) in whom atezolizumab + bevacizumab therapy is contraindicated. The aim of the study was the identification of a miRNA signature in liquid biopsy related to sorafenib response. Methods: miRNAs were profiled in hepatoblastoma HepG2 cells and tested in animal models, extracellular vesicles (EVs), and plasma from HCC patients. Results: Sorafenib altered the expression of 11 miRNAs in HepG2 cells. miR-200c-3p and miR-27a-3p exerted an anti-tumoral activity by decreasing cell migration and invasion, whereas miR-122-5p, miR-148b-3p, miR-194-5p, miR-222-5p, and miR-512-3p exerted pro-tumoral properties by increasing cell proliferation, migration, or invasion, or decreasing apoptosis. Sorafenib induced a change in EVs population with an increased number of larger EVs, and promoted an accumulation of miR-27a-3p, miR-122-5p, miR-148b-3p, miR-193b-3p, miR-194-5p, miR-200c-3p, and miR-375 into exosomes. In HCC patients, circulating miR-200c-3p baseline levels were associated with increased survival, whereas high levels of miR-222-5p and miR-512-3p after 1 month of sorafenib treatment were related to poor prognosis. The RNA sequencing revealed that miR-200c-3p was related to the regulation of cell growth and death, whereas miR-222-5p and miR-512-3p were related to metabolic control. Conclusions: The study showed that Sorafenib regulates a specific miRNA signature in which miR-200c-3p, miR-222-5p, and miR-512-3p bear prognostic value and contribute to treatment response.

Link of sorafenib resistance with the tumor microenvironment in hepatocellular carcinoma: Mechanistic insights

Sorafenib, a multi-kinase inhibitor with antiangiogenic, antiproliferative, and proapoptotic properties, is the first-line treatment for patients with late-stage hepatocellular carcinoma (HCC). However, the therapeutic effect remains limited due to sorafenib resistance. Only about 30% of HCC patients respond well to the treatment, and the resistance almost inevitably happens within 6 months. Thus, it is critical to elucidate the underlying mechanisms and identify effective approaches to improve the therapeutic outcome. According to recent studies, tumor microenvironment (TME) and immune escape play critical roles in tumor occurrence, metastasis and anti-cancer drug resistance. The relevant mechanisms were focusing on hypoxia, tumor-associated immune-suppressive cells, and immunosuppressive molecules. In this review, we focus on sorafenib resistance and its relationship with liver cancer immune microenvironment, highlighting the importance of breaking sorafenib resistance in HCC.

Extracellular Vesicles and Circulating Tumour Cells - complementary liquid biopsies or standalone concepts?

Liquid biopsies do promise a lot, but are they keeping it? In the past decade, additional novel biomarkers qualified to be called like that, of which, some took necessary hurdles resulting in FDA approval and clinical use. Some others are since a while around, well known and were once regarded to be a game changer in cancer diagnosis or cancer screening. But, during their clinical use limitations were observed from statistical significance and questions raised regarding their robustness, that eventually led to be dropped from associated clinical guidelines for certain applications including cancer diagnosis. The purpose of this review isn't to give a broad overview of all current liquid biopsy as biomarkers, weight them and promise a brighter future in cancer prevention, but rather to take a deeper look on two of those who do qualify to be called liquid biopsies now or then. These two are probably of greatest interest conceptually and methodically, and likely have the highest chances to be in clinical use soon, with a portfolio extension over their original conceptual usage. We aim to dig deeper beyond cancer diagnosis or cancer screening. Actually, we aim to review in depth extracellular vesicles (EVs) and compare with circulating tumour cells (CTCs). The latter methodology is partially FDA approved and in clinical use. We will lay out similarities as taking advantage of surface antigens on EVs and CTCs in case of characterization and quantification. But drawing readers' attention to downstream application based on capture/isolation methodology and simply on their overall nature, here apparently being living material eventually recoverable as CTCs are vs. dead material with transient effects on recipient cell as in case of EVs. All this we try to bring in perspective, compare and conclude towards which future direction we are aiming for, or should aim for. Do we announce a winner between CTCs vs EVs? No, but we provide good reasons to intensify research on them.

Prognostic Value of Exosomal Noncoding RNA in Hepatocellular Carcinoma: A Meta-analysis

High morbidity, recurrence and mortality make hepatocellular carcinoma (HCC) a leading cause of cancer-related burden and deaths. The lack of prognostic evaluation methods weakened the therapeutic efficacy for HCC. Exosomal noncoding RNAs (ncRNAs) play a key role in cancer development. Our meta-analysis aimed to assess the prognostic value of exosome-transferred noncoding RNAs in predicting the outcomes of patients with HCC. We obtained 16 articles from PubMed, Web of Science, Scopus and EMBASE up to 4 November 2021. The ncRNAs were divided into three parts：microRNAs (miRNA), long noncoding RNAs (lncRNA) and circular RNAs (circRNA). In the pooled hazard ratios (HRs), upregulated miRNAs were 3.06 (95% CI = 2.51-3.73), downregulated miRNAs were 3.28 (95% CI = 2.61-4.11), lncRNAs were 3.34 (95% CI = 1.87-5.96), and circRNAs were 1.76 (95% CI = 1.36-2.14). As the results of subgroup analysis, upregulated miRNAs had a pooled HR of 3.10 (95% CI = 1.66-5.81), and the HR of downregulated miRNAs was 3.04 (95% CI = 2.17-4.28) for multivariate analysis of overall survival (OS). Meanwhile, upregulated miRNAs had a pooled HR of 2.61 (95% CI = 1.89-3.60), and the HR of downregulated miRNAs was 3.77 (95% CI = 1.11-12.73) for multivariate analysis of other endpoints. Remarkably, miR-21 has a pooled HR of 2.48 (95%CI = 1.52-4.05, I 2 = 0) for disease-free survival (DFS). In conclusion, the expression of exosomal noncoding RNAs can be used to evaluate the prognosis of patients with HCC. Exosome-transferred miR-21 might serve as a potential prognostic biomarker in HCC.

Emerging role of exosomes in cancer progression and tumor microenvironment remodeling

Cancer is one of the leading causes of death worldwide, and the factors responsible for its progression need to be elucidated. Exosomes are structures with an average size of 100 nm that can transport proteins, lipids, and nucleic acids. This review focuses on the role of exosomes in cancer progression and therapy. We discuss how exosomes are able to modulate components of the tumor microenvironment and influence proliferation and migration rates of cancer cells. We also highlight that, depending on their cargo, exosomes can suppress or promote tumor cell progression and can enhance or reduce cancer cell response to radio- and chemo-therapies. In addition, we describe how exosomes can trigger chronic inflammation and lead to immune evasion and tumor progression by focusing on their ability to transfer non-coding RNAs between cells and modulate other molecular signaling pathways such as PTEN and PI3K/Akt in cancer. Subsequently, we discuss the use of exosomes as carriers of anti-tumor agents and genetic tools to control cancer progression. We then discuss the role of tumor-derived exosomes in carcinogenesis. Finally, we devote a section to the study of exosomes as diagnostic and prognostic tools in clinical courses that is important for the treatment of cancer patients. This review provides a comprehensive understanding of the role of exosomes in cancer therapy, focusing on their therapeutic value in cancer progression and remodeling of the tumor microenvironment.

Tumor-associated Exosomes Are Involved in Hepatocellular Carcinoma Tumorigenesis, Diagnosis, and Treatment

Hepatocellular carcinoma (HCC) has become a challenging disease worldwide. There are still limitations in the diagnosis and treatment of HCC, and its high metastatic capacity and high recurrence rate are the main reasons for its poor prognosis. The ability of extracellular vesicles (EVs) to transfer functionally-active substances and their widespread presence in almost all body fluids suggest their unprecedented potential in the study of various cancers. The unique physicochemical properties of EVs determine their potential as antitumor vaccines and drug carriers. In the last decade, the study of EVs in HCC has evolved from a single hot topic to a system with considerable scale. This paper summarizes the role of EVs, especially exosomes, in the occurrence, metastasis and tumor immunity of HCC, reviews their applications in tumor diagnosis, prognosis and treatment, describes the pros and cons of these studies, and looks forward towards the future research directions of EVs in HCC.

Analysis of the expression, function and signaling of glycogen phosphorylase isoforms in hepatocellular carcinoma

Glycogen phosphorylase (GP) is an essential enzyme for glycolysis via the glycogen degradation pathway. It consists of three isoforms: PYGB (brain form), PYGL (liver form) and PYGM (muscle form). Although the abnormal expression of GP is associated with a variety of tumors, its relationship with hepatocellular carcinoma (HCC) and whether it can be used as a prognostic marker of HCC remains unclear. In the present study, the expression levels of PYGB, PYGL and PYGM were analyzed. It was found that the expression levels of PYGB in tumor tissues were higher than those in normal tissues, particularly in HCC. The high expression of PYGB (hazard ratios=1.801; 95% confidence interval: 1.266-2.562) could predict the poor prognosis of HCC patients but not PYGL and PYGM. Inhibition of PYGB with GP inhibitor CP91149 significantly suppressed the HCC cell proliferation in the HCC cell model. In addition, combination treatment with sorafenib, a standard treatment for HCC, showed a great inhibition on tumor growth and angiogenesis. These findings suggested that PYGB may be used as a therapeutic and prognostic indicator for HCC.

A Novel Exosome-Relevant Molecular Classification Uncovers Distinct Immune Escape Mechanisms and Genomic Alterations in Gastric Cancer

Objective: Gastric cancer (GC) is a highly heterogeneous malignant carcinoma. This study aimed to conduct an exosome-based classification for assisting personalized therapy for GC.

Methods: Based on the expression profiling of prognostic exosome-related genes, GC patients in The Cancer Genome Atlas (TCGA) cohort were classified using the unsupervised consensus clustering approach, and the reproducibility of this classification was confirmed in the GSE84437 cohort. An exosome-based gene signature was developed via Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis. Immunological features, responses to immune checkpoint inhibitors, and genetic alterations were evaluated via computational methods.

Results: Two exosome-relevant phenotypes (A and B) were clustered, and this classification was independent of immune subtypes and TCGA subtypes. Exosome-relevant phenotype B had a poorer prognosis and an inflamed tumor microenvironment (TME) relative to phenotype A. Patients with phenotype B presented higher responses to the anti-CTLA4 inhibitor. Moreover, phenotype B occurred at a higher frequency of genetic mutation than phenotype A. The exosome-based gene signature (GPX3, RGS2, MATN3, SLC7A2, and SNCG) could independently and accurately predict GC prognosis, which was linked to stromal activation and immunosuppression.

Conclusion: Our findings offer a conceptual frame to further comprehend the roles of exosomes in immune escape mechanisms and genomic alterations of GC. More work is required to evaluate the reference value of exosome-relevant phenotypes for designing immunotherapeutic regimens.

Vitamin D Reverts the Exosome-Mediated Transfer of Cancer Resistance to the mTOR Inhibitor Everolimus in Hepatocellular Carcinoma

Several multi-kinase inhibitors were widely tested as potential first-line or second-line therapy in patients with advanced hepatocellular carcinoma (HCC). However, acquired drug resistance limits their clinical efficacy. Exosomes are microvesicles secreted by tumor and stromal cells that participate in many biological processes, including drug resistance. The current study evaluated the capability of exosomes derived from everolimus (EVE)-resistant HCC cells in inducing drug resistance in parental human HCC cells and the effect of 1,25(OH)₂Vitamin D (VitD) treatment in restoring EVE sensitivity. The internalization of exosomes from EVE-resistant (EveR) cells into parental cells conferred the transmission of aggressive phenotype by promoting the transition of epithelial-to-mesenchymal phenotype, as demonstrated by immunofluorescence, and the acquisition of EVE resistance, as demonstrated by cell proliferation and colony formation assays. Moreover, the internalization of exosomes from EveR into parental cells induced deregulation of the mTOR pathway mainly by triggering the activation of the serine/threonine protein kinase Akt, involved in the cellular survival pathway, as demonstrated by Western blot analysis. Interestingly, the treatment with VitD prevented exosome-induced EVE resistance in HCC cells, significantly inhibiting cell proliferation but also partially reducing colony and size number when combined with EVE compared with control. In conclusion, the results of the current study demonstrated that exosomes derived from EveR cells could induce EVE resistance in EVE-sensitive HCC cells and that VitD can revert the exosome-induced EVE resistance by resensitizing to EVE treatment.

Improved Aitongxiao prescription (I-ATXP) induces apoptosis, cell cycle arrest and blocks exosomes release in hepatocellular carcinoma (HCC) cells

BACKGROUND

Hepatocellular carcinoma (HCC) is the second most common malignancy globally, after lung cancer, accounting for 85-90% of primary liver cancer. Hepatitis B virus (HBV) infection is considered the leading risk factor for HCC development in China. HCC is a highly malignant cancer whose metastasis is primarily influenced by the tumor microenvironment. The role of exosomes in cancer development has become the focus of much research due to the many newly described contents of exosomes, which may contribute to tumorigenesis. However, the possible role exosomes play in the interactions between HCC cells and their surrounding hepatic milieu is mainly unknown. We discovered an Improved Aitongxiao Prescription (I-ATXP): an 80% alcohol extract from a mix of 15 specific plant and animal compounds, which had been shown to have an anticancer effect through inducing apoptosis and cell cycle arrest and blocking exosomes release in HCC cells. However, the anticancer mechanism of I-ATXP on human liver carcinoma is still unclear.

OBJECTIVE

Due to its inhibitory effects on chemical carcinogenesis and inflammation, I-ATXP has been proposed as an effective agent for preventing or treating human liver carcinoma. In this study, we aimed to explore the effect of I-ATXP on proliferation, apoptosis, and cell cycles of different HCC cell lines. We investigated the impact of I-ATXP on exosomes' secretion derived from these HCC cells.

METHODS

The inhibitory effect of I-ATXP on proliferation and cytotoxicity of HepG2, SMMC7721, HKCL-C3 HCC cell lines, and MIHA immortalized hepatocyte cell line was assessed by CCK-8 assay. The cell cycle distribution and cell apoptosis were determined by flow cytometry using Annexin V-FITC/PI staining. The expression of Alix and CD63 of exosome marker proteins was detected by western blotting. The exosome protein concentration was measured by a fluorescent plate reader. The exosome-specific enzyme activity was measured by acetylcholinesterase (AchE) assay, and exosome morphological characteristics were identified by transmission electron microscopy (TEM).

RESULTS

I-ATXP inhibited the growth of HCC cells in a dose and time-dependent manner. Flow cytometry analysis showed that I-ATXP induced G0/G1 phase arrest and cell apoptosis. The I-ATX reduced HepG2, SMMC7721, and HKCI-C HCC cell lines exosomes release and low-dose I-ATXP significantly enhanced the growth inhibition induced by 5-Fu. Western blot analysis shows that after HCC cell lines were treated with various concentrations of I-ATXP (0.125-1 mg/ml) for 24 h, exosomes derived from three different HCC cells expressed exosome-specific proteins Alix and CD63. Compared with the untreated group, with the increment of the concentration of I-ATXP, the expression of exosome-specific proteins Alix and CD63 were reduced. These results suggest that I-ATXP can inhibit the release of exosomes with Alix and CD63 protein from HCC cells.

CONCLUSIONS

I-ATXP is a traditional Chinese medicine that acts as an effective agent for preventing or treating human liver carcinoma. (i) I-ATXP can effectively inhibit cell proliferation of different HCC cells in a time and dose-dependent manner. Compared with 5-Fu, I-ATXP exhibited more selective proliferation inhibition in HCC cells, displaying traditional Chinese medicine advantages on tumor therapy and providing the experimental basis for I-ATXP clinical application. (ii) I-ATXP can induce apoptosis and cell cycle arrest in HCC cells. The CCK-8 assay results indicated that I-ATXP could inhibit HCC cell proliferation mediated by apoptosis and cell cycle arrest. (iii) I-ATXP can inhibit both the exosome releases and expression of CD63, and Alix derived from HCC cells, but the exosomes derived from liver cancer cells affect liver cancer cells' biological properties such as proliferation, invasion, and migration. These suggest that I-ATXP may affect HCC cells via regulation of exosomes of HCC cells, further indicating the potential clinical values of I-ATXP for the prevention or treatment of human liver carcinoma.

Exosomes in Pathogenesis, Diagnosis, and Treatment of Hepatocellular Carcinoma

Exosomes are extracellular vesicles with a diameter of 30-150 nm that are released by most types of cells and have been confirmed to be involved in many physical and pathological processes, especially in cell to cell communication. Compared with other vesicles, exosomes have a unique double-layer saclike structure that allows them to be present stably in various body fluids, including blood, cerebrospinal fluid, urine, saliva, and serous cavity effusion. The cargoes of exosomes reflect the characteristics of host cells. Due to the nature of hepatocellular carcinoma (HCC) cells, heterogeneity in the bioactive substances usually exist in exosomes. In addition, exosomes can efficiently deliver cargoes to the target cells to exert pathological functions, playing important role in tumor occurrence, development, metastasis, immune regulation, and drug resistance. Previous studies have been shown that exosomes have wide applications in diagnosis and treatment of HCC. In this review, we discuss these recent findings and highlight the significant roles of exosomes in HCC, focusing on the effect and underlying mechanisms of exosomes to regulate HCC progression and the potential clinical value of exosomes as biomarkers and therapeutic targets.

Current Perspectives on the Unique Roles of Exosomes in Drug Resistance of Hepatocellular Carcinoma

As a common malignant tumor worldwide, the prognosis of hepatocellular carcinoma (HCC) remains unsatisfactory, even though treatment methods have improved. Despite the developments in traditional chemotherapy and emerging targeted immunotherapy, the problem of recurrence and metastasis of HCC and adverse effects on survival and prognosis are still serious. Drug resistance is a daunting challenge that impedes HCC treatment. Exosomes, a class of extracellular vesicles ranging in size from 30 to 100 nm, have been the focus of recent studies. Exosomes can activate various signaling pathways and regulate the tumor microenvironment with their cargo, which includes functional lipids, proteins, and nucleic acids. Thus, they change the phenotype of recipient cells via exosome-mediated communication. Exosomes secreted by tumors or stromal cells can also transfer drug-resistant traits to other tumor cells. However, their effects on drug resistance in HCC are not completely understood. In this review, we summarize and discuss the underlying relationship between exosomes and drug resistance in HCC. In addition, we also show that exosomes may act as candidate biomarkers for predicting and monitoring drug responses and as potential targets or vectors to reverse the drug resistance of HCC.

Knockdown of ST6Gal-I expression in human hepatocellular carcinoma cells inhibits their exosome-mediated proliferation- and migration-promoting effects

Abnormal sialylation is a distinctive feature of human hepatocellular carcinoma (HCC) and is closely related to its malignant properties. Exosomes have characteristic protein and lipid composition; however, the results concerning glycoprotein composition and glycosylation are scarce. In this study, liquid chromatography-tandem mass spectrometry (LC-MS/MS) identified multiple microvesicle-related sialylated proteins including CD63, a classic marker of exosomes. The silencing of α2,6-sialyltransferase I (ST6Gal-I) significantly reduced the levels of α2,6-sialylated glycoconjugates on CD63 and the surface of HCC-derived exosomes (HCC-exo). And surface glycoconjugates play important roles in exosomes biogenesis and in their interaction with other cells. Compared to exosomes derived from naive HCC cells, α2,6-sialylation degradation abolished both the proliferation-promoting and migration-promoting effects of HCC-exo. Further analysis revealed that the Akt/GSK-3β or JNK1/2 signaling mediates HCC-exo-mediated proliferation in HCC cells, while ST6Gal-I silencing deactivated this pathway. These findings suggest that a loss of α2,6-sialylation decreases HCC progression through the loss of cancer cell-derived exosomes; furthermore, it opens novel perspectives to further explore the functional role of glycans in the biology of exosomes.

Role of Tetraspanins in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is characterized by high prevalence, morbidity, and mortality. Liver cancer is the sixth most common cancer worldwide; and its subtype, HCC, accounts for nearly 80% of cases. HCC progresses rapidly, and to date, there is no efficacious treatment for advanced HCC. Tetraspanins belong to a protein family characterized by four transmembrane domains. Thirty-three known tetraspanins are widely expressed on the surface of most nucleated cells and play important roles in different biological processes. In our review, we summarize the functions of tetraspanins and their underlying mechanism in the life cycle of HCC, from its initiation, progression, and finally to treatment. CD9, TSPAN15, and TSPAN31 can promote HCC cell proliferation or suppress apoptosis. CD63, CD151, and TSPAN8 can also facilitate HCC metastasis, while CD82 serves as a suppressor of metastasis. TSPAN1, TSPAN8, and CD151 act as prognosis indicators and are inversely correlated to the overall survival rate of HCC patients. In addition, we discuss the potential of role of the tetraspanin family proteins as novel therapeutic targets and as an approach to overcome drug resistance, and also provide suggestions for further research.

Underlying mechanism of sorafenib resistance in hepatocellular carcinoma: a bioinformatics study based on validated resistance-related genes

Background

Sorafenib, the first approved targeted therapy for advanced hepatocellular carcinoma (HCC), is often reported to comprised survival-benefit due to resistance. An underlying mechanism of resistance was proposed using bioinformatics analysis based on differentially expressed genes (DEGs) from microarrays. However, most DEGs were invalidated at both the expression level, and the role in causing resistance. Therefore, we conducted a bioinformatics analysis based on experimentally determined sorafenib-resistance-related genes (SRRGs) to elucidate the mechanism of sorafenib resistance.

Methods

The SRRGs, which have been experimentally determined to promote or inhibit resistance, were collected from published studies. The Database for Annotation, Visualization and Integrated Discovery (DAVID) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to perform Gene Ontology (GO) and pathway enrichment analysis, respectively. A corresponding protein-protein interaction network (PPI) was created using the Cytoscape software program, and network hub genes were proposed.

Results

A total of 145 SRRGs, with 117 promoting and 28 inhibiting resistance, were identified. Cell proliferation, migration, development, response to oxygen levels, epithelial-to-mesenchymal transition (EMT), cell skeleton, protein function, and autophagy were all proposed as crucial gene functions related to resistance. The pathways related to cell proliferation or apoptosis, immune function, endocrine metabolism, stem cell function, and differentiation were identified as key resistance-related pathways. A total of 81 hub genes were proposed, including the following top 10 genes: TP53, AKT1, EGFR, STAT3, VEGFA, JUN, MAPK1, IL6, PTEN, and CTNNB1.

Conclusions

In conclusion, this study gathered experimentally validated genes that determine sorafenib resistance in HCC, provided an overview of the underlying mechanisms of resistance, and further validated sorafenib resistance in HCC.

MiR-185-5p targets RAB35 gene to regulate tumor cell-derived exosomes-mediated proliferation, migration and invasion of non-small cell lung cancer cells

Introduction: Non-small cell lung cancer (NSCLC) is the most common malignant tumor, and its recurrence and metastasis are the main causes of death. Recently, there is evidence that tumor derived exosomes play an important role in the occurrence and development of NSCLC.

Objective’s methods: First, the expression of miR-185-5p and RAB35 in NSCLC tissues, paracancerous tissues, NSCLC cell lines and normal human bronchial epithelial cell line was detected. Then, a series of gain-and loss-of-function assays were performed to validate the effects of miR-185-5p or RAB35 effects on A549 and H2170 cells proliferation, migration and invasion. Next, online bioinformatics analysis and luciferase reporter were used to predict and validate the targeting relationship of miR-185-5p and RAB35. Finally, tumor cell-derived exosomes with genetic downregulation of RAB35 or overexpression of miR-185-5p were co cultured with their parental cells to verify the regulatory role of RAB35 on exosome secretion and function.

Results: In NSCLC tissues and cell lines, miR-185-5p was downregulated, while RAB35 was significantly upregulated. Overexpression of miR-185-5p or knockdown of RAB35 expression inhibited cell proliferation, migration and invasion. Furthermore, we elucidated that RAB35 is a direct target of miR-185-5p. Additionally, exosomes derived from tumor cells restored cell proliferation, migration and invasion, whereas exosomes secreted by tumor cells with downregulation of RAB35 expression or overexpression of miR-185-5p lost their ability to restore cell proliferation, migration and invasion.

Conclusions: Our results demonstrate that miR-185-5p inhibits tumor cell-derived exosomes-mediated proliferation, migration and invasion of NSCLC cells by downregulating RAB35 expression.

Bone marrow mesenchymal stem cells-secreted exosomal microRNA-205-5p exerts inhibitory effect on the progression of liver cancer through regulating CDKL3

OBJECTIVE

Bone marrow mesenchymal stem cells-derived exosomes (BMSCs-exo) carrying microRNA (miR) cargo have been emerged as a promising therapy for human cancers. Therein, we pivoted on the integral function of BMSCs-exo and miR-205-5p in liver cancer through mediation of cyclin-dependent kinase-like 3 (CDKL3).

METHODS

Patients with liver cancer were enrolled to collect the clinical tissue and determine miR-205-5p and CDKL3 expression. miR-205-5p expression in BMSCs was altered by transfection, and BMSCs-exo were extracted and co-cultured with LM3 cells. Meanwhile, LM3 cells were independently transfected with CDKL3 low or high expression vector. Since then, cell growth in vitro was observed, and the effect of exosomal miR-205-5p on tumor growth in vivo was further investigated.

RESULTS

miR-205-5p expression was low while CDKL3 was high in liver cancer. BMSCs-exo blocked cellular growth of liver cancer in vitro and in vivo. Overexpressing exosomal miR-205-5p decelerated the biological development of liver cancer cells while suppressing exosomal miR-205-5p had the contrary function in vitro and in vivo. Loss of CDKL3 impaired the malignant activities of liver cancer cells, and could even impair the pro-tumor effects of down-regulated exosomal miR-205-5p.

CONCLUSION

It is clearly concluded that BMSCs-secreted exosomal miR-205-5p exerts inhibitory effect on the progression of liver cancer through regulating CDKL3.

Extracellular Vesicles as Mediators of Cancer Disease and as Nanosystems in Theranostic Applications

Cancer remains a leading cause of death worldwide despite decades of intense efforts to understand the molecular underpinnings of the disease. To date, much of the focus in research has been on the cancer cells themselves and how they acquire specific traits during disease development and progression. However, these cells are known to secrete large numbers of extracellular vesicles (EVs), which are now becoming recognized as key players in cancer. EVs contain a large number of different molecules, including but not limited to proteins, mRNAs, and miRNAs, and they are actively secreted by many different cell types. In the last two decades, a considerable body of evidence has become available indicating that EVs play a very active role in cell communication. Cancer cells are heterogeneous, and recent evidence reveals that cancer cell-derived EV cargos can change the behavior of target cells. For instance, more aggressive cancer cells can transfer their "traits" to less aggressive cancer cells and convert them into more malignant tumor cells or, alternatively, eliminate those cells in a process referred to as "cell competition". This review discusses how EVs participate in the multistep acquisition of specific traits developed by tumor cells, which are referred to as "the hallmarks of cancer" defined by Hanahan and Weinberg. Moreover, as will be discussed, EVs play an important role in drug resistance, and these more recent advances may explain, at least in part, why pharmacological therapies are often ineffective. Finally, we discuss literature proposing the use of EVs for therapeutic and prognostic purposes in cancer.

Exosomal DLX6-AS1 from hepatocellular carcinoma cells induces M2 macrophage polarization to promote migration and invasion in hepatocellular carcinoma through microRNA-15a-5p/CXCL17 axis

Background

Hepatocellular carcinoma (HCC) cells-secreted exosomes (exo) could stimulate M2 macrophage polarization and promote HCC progression, but the related mechanism of long non-coding RNA distal-less homeobox 6 antisense 1 (DLX6-AS1) with HCC-exo-mediated M2 macrophage polarization is largely ambiguous. Thereafter, this research was started to unearth the role of DLX6-AS1 in HCC-exo in HCC through M2 macrophage polarization and microRNA (miR)-15a-5p/C-X-C motif chemokine ligand 17 (CXCL17) axis.

Methods

DLX6-AS1, miR-15a-5p and CXCL17 expression in HCC tissues and cells were tested. Exosomes were isolated from HCC cells with overexpressed DLX6-AS1 and co-cultured with M2 macrophages. MiR-15a-5p/CXCL17 down-regulation assays were performed in macrophages. The treated M2 macrophages were co-cultured with HCC cells, after which cell migration, invasion and epithelial mesenchymal transition were examined. The targeting relationships between DLX6-AS1 and miR-15a-5p, and between miR-15a-5p and CXCL17 were explored. In vivo experiment was conducted to detect the effect of exosomal DLX6-AS1-induced M2 macrophage polarization on HCC metastasis.

Results

Promoted DLX6-AS1 and CXCL17 and reduced miR-15a-5p exhibited in HCC. HCC-exo induced M2 macrophage polarization to accelerate migration, invasion and epithelial mesenchymal transition in HCC, which was further enhanced by up-regulated DLX6-AS1 but impaired by silenced DLX6-AS1. Inhibition of miR-15a-5p promoted M2 macrophage polarization to stimulate the invasion and metastasis of HCC while that of CXCL17 had the opposite effects. DLX6-AS1 mediated miR-15a-5p to target CXCL17. DLX6-AS1 from HCC-exo promoted metastasis in the lung by inducing M2 macrophage polarization in vivo.

Conclusion

DLX6-AS1 from HCC-exo regulates CXCL17 by competitively binding to miR-15a-5p to induce M2 macrophage polarization, thus promoting HCC migration, invasion and EMT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01973-z.

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.