Exosome miR-134-5p restrains breast cancer progression via regulating PI3K/AKT pathway by targeting ARHGAP1

Transcription factor GTF2I regulates osteoclast differentiation through mediating miR-134-5p and MAT2A expressions

This study explored the possible effect of transcription factor GTF2I on the differentiation of osteoclasts and its regulation on the miR-134-5p/MAT2A axis. RANKL-induced osteoclasts were measured for expressions of GTF2I, miR-134-5p, and MAT2A. The number and size of osteoclasts were assessed after TRAP staining. The expressions of osteoclast differentiation biomarkers, NFATC1, TRAP, and CTSK, were detected as well. The relationships of the GTF2I/miR-134-5p/MAT2A axis were verified by ChIP, dual luciferase, and RNA pull-down assay. In vivo experiments were conducted on ovariectomized (OVX)-treated mice to determine the effect of GTF2I overexpression on osteoclast differentiation and bone loss. RANKL-induced osteoclasts had suppressed expressions of GTF2I and miR-134-5p and increased expression of MAT2A. GTF2I overexpression or miR-134-5p overexpression contributed to decreased cell number and size and suppressed cell differentiation, whereas such an effect can be abolished by overexpression of MAT2A. GTF2I can bind the miR-134-5p promoter to regulate its expression, whereas miR-134-5p can negatively regulate MAT2A expression. The protective effect of GTF2I overexpression against bone loss and cell differentiation was verified by in vivo experiments. Collectively, these results indicate that GTF2I can mediate miR-134-5p expression to increase MAT2A expression, contributing to the suppression of osteoclast differentiation.

Exosomes, autophagy, and cancer: A complex triad

Cancer remains one of the leading causes of death worldwide. Despite remarkable progress in prevention, diagnosis, and therapy, the incidence of certain types of cancer persists, urging the identification of clinically relevant biomarkers and the development of novel therapeutic strategies to improve clinical outcomes and overcome treatment resistance. Exosomes, small extracellular vesicles released by diverse types of cells, have attracted interest in biomedical research due to their potential as carriers for different treatments. Moreover, exosomes play a pivotal role in intercellular communication, modulating various cellular processes. One of those is autophagy, a pro-survival pathway that is essential for human cells. Even though autophagy is traditionally described as a catabolic route, its machinery is intricately involved in various cellular responses, including vesicle formation and secretion. In this regard, the link between autophagy and exosomes is complex, bidirectional, and highly dependent on the cellular context. Interestingly, both processes have been extensively implicated in cancer pathogenesis, highlighting their potential as therapeutic targets. This review updates our understanding of how exosomes can participate in cancer development and progression, with a specific focus on their influence on tumor growth, angiogenesis, and metastasis. Additionally, the interplay between these extracellular vesicles and autophagy is minutely reviewed and discussed, as we hypothesize that this crosstalk may hold valuable clues for biomarker discovery and the development of novel therapeutic strategies.

Exosomes Mediate the Production of Oxaliplatin Resistance and Affect Biological Behaviors of Colon Cancer Cell Lines

BACKGROUND

Colon cancer has high mortality rate which making it one of the leading causes of cancer deaths. Oxaliplatin is a common chemotherapeutic drug, but it has disadvantages such as drug resistance.

OBJECTIVE

The purpose of this study is to explore the mechanism of exosomes in the resistance of oxaliplatin and verify whether elemene and STAT3 inhibitors reverse the resistance to oxaliplatin.

METHODS

Related cell line models were constructed and the proliferation, migration, invasion, apoptosis and resistance to oxaliplatin were evaluated for all three cells of HCT116/L, sensitive cell HCT116 and HCT116+HCT116/L-exosomes (HCT116-exo). It was to explore probable signaling pathways and mechanisms by Western blotting.

RESULTS

HCT116-exo drug-resistant chimeric cells showed greater capacity for proliferation, migration and invasion than HCT116 sensitive cells. After the above cells were treated with oxaliplatin, the apoptosis rate of chimeric drug-resistant cells HCT116-exo and its IC50 increased compared with the sensitive cells HCT116. The proliferation, invasion and migration of cells treated with STAT3 inhibitor or β-elemene combined with oxaliplatin reduced compared with those treated with oxaliplatin or β-elemene alone. The STAT3 inhibitor or β-elemene in combination with oxaliplatin increased the rate of apoptosis relative to oxaliplatin or β-elemene alone. Drug-resistant cell exosomes could promote the EMT process, related to the participation of FGFR4, SHMT2 and STAT3 inhibitors.

CONCLUSION

Drug-resistant cell exosomes could induce resistance, and improve the capacity of colon cancer towards proliferate, invade, migrate and promote the EMT process. The β-elemene combined with oxaliplatin could reverse the above results which might be related to the STAT3 pathway and EMT pathway in colon cancer.

Exosomal microRNA as a key regulator of PI3K/AKT pathways in human tumors

MicroRNAs (miRNAs) are conserved non-protein-coding RNAs that are naturally present in organisms and can control gene expression by suppressing the translation of mRNA or causing the degradation of mRNA. MicroRNAs are highly concentrated in the PI3K/AKT pathway, and abnormal activation of the PI3K/AKT pathway plays a role in cancer progression. The AKT/PI3K pathway is critical for cellular functions and can be stimulated by cytokines and in normal situations. It is involved in regulating various intracellular signal transduction, including development, differentiation, transcriptional regulation, protein, and synthesis. There is a growing body of evidence indicating that miRNAs, which are abundant in exosomes released by different cells, can control cellular biological activities via modulating the PI3K/AKT pathway, hence influencing cancer progression and drug resistance. This article provides an overview of the latest research progress regarding the function and medical use of the PI3K/AKT pathway and exosomal miRNA/AKT/PI3K axis in the behaviors of cancer cells.

Cellular and Exosomal MicroRNAs: Emerging Clinical Relevance as Targets for Breast Cancer Diagnosis and Prognosis

Breast cancer accounts for the highest cancer cases globally, with 12% of occurrences progressing to metastatic breast cancer with a low survival rate and limited effective early intervention strategies augmented by late diagnosis. Moreover, a low concentration of prognostic and predictive markers hinders disease monitoring. Circulating and exosomal microRNAs (miRNAs) have recently shown a considerable interplay in breast cancer, standing out as effective diagnostic and prognostic markers. The primary functions are as gene regulatory agents at the genetic and epigenetic levels. An array of dysregulated miRNAs stimulates cancer-promoting mechanisms, activating oncogenes and controlling tumor-suppressing genes and mechanisms. Exosomes are vastly studied extracellular vesicles, carrying, and transporting cargo, including noncoding RNAs with premier roles in oncogenesis. Translocation of miRNAs from the circulation to exosomes, with RNA-binding proteins in stress-induced conditions, has shown significant cooperation in function to promote breast cancer. This review examines cellular and exosomal miRNA biogenesis and loading, the clinical implications of their dysregulation, their function in diagnosis, prognosis, and prediction of breast cancer, and in regulating cancer signaling pathways. The influence of cellular and exosomal miRNAs presents clinical significance on breast cancer diagnosis, subtyping, staging, prediction, and disease monitoring during treatment, hence a potent marker for breast cancer.

Curcumin targets miR-134-5p to suppress the progression of colorectal cancer through regulating the CDCA3/CDK1 pathway

It has been reported the anti-tumor action of curcumin on colorectal cancer. In this study, we aimed to explore the potential mechanisms underlying curcumin in the development of colorectal cancer. CCK-8, EdU, flow cytometry, and transwell invasion assays were conducted to investigate the function role of curcumin in cell proliferation, apoptosis, and invasion. The level of miR-134-5p and CDCA3 was determined using RT-qPCR analysis. Western blot was applied for detecting the levels of c-myc, MMP9, CDCA3, and CDK1. Dual-luciferase reporter assay was used to evaluate the relationship between miR-134-5p and CDCA3, and IP assay was performed to examine the interaction between CDCA3 and CDK1. Additionally, SW620 cells were injected into the mice to form the xenograft tumor model. Curcumin treatment repressed cell growth and invasion, and induced cell apoptosis in HCT-116 and SW620 cells. Curcumin elevated miR-134-5p expression and restrained CDCA3 expression in HCT-116 and SW620 cells. MiR-134-5p inhibitor or CDCA3 overexpression could restore the effects of curcumin on cell growth, apoptosis, and invasion in HCT-116 and SW620 cells. MiR-134-5p targeted CDCA3, and CDCA3 could rescue the repressive effects of miR-134-5p on the progression of colorectal cancer. Moreover, CDCA3 interacted with CDK1, and CDK1 overexpression blocked the suppressive effects of CDCA3 downregulation on the development of colorectal cancer. In addition, curcumin treatment repressed tumor growth in colorectal cancer via increasing miR-134-5p and downregulating CDCA3 and CDK1 expression in vivo. Our findings provided the evidence that curcumin upregulated miR-134-5p to inhibit the progression of colorectal cancer by regulating CDCA3/CDK1 pathway.

Construction of a prognostic risk score model based on the ARHGAP family to predict the survival of osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most common primary malignancy of bone tumors. More and more ARHGAP family genes have been confirmed are to the occurrence, development, and invasion of tumors. However, its significance in osteosarcoma remains unclear. In this study, we aimed to identify the relationship between ARHGAP family genes and prognosis in patients with OS.

METHODS

OS samples were retrieved from the TCGA and GEO databases. We then performed LASSO regression analysis and multivariate COX regression analysis to select ARHGAP family genes to construct a risk prognosis model. We then validated this prognostic model. We utilized ESTIMATE and CIBERSORT algorithms to calculate the stroma and immune scores of samples, as well as the proportions of tumor infiltrating immune cells (TICs). Finally, we conducted in vivo and in vitro experiments to investigate the effect of ARHGAP28 on osteosarcoma.

RESULTS

We selected five genes to construct a risk prognosis model. Patients were divided into high- and low-risk groups and the survival time of the high-risk group was lower than that of the low-risk group. The high-risk group in the prognosis model constructed had relatively poor immune function. GSEA and ssGSEA showed that the low-risk group had abundant immune pathway infiltration. The overexpression of ARHGAP28 can inhibit the proliferation, migration, and invasion of osteosarcoma cells and tumor growth in mice, and IHC showed that overexpression of ARHGAP28 could inhibit the proliferation of tumor cells.

CONCLUSION

We constructed a risk prognostic model based on five ARHGAP family genes, which can predict the overall survival of patients with osteosarcoma, to better assist us in clinical decision-making and individualized treatment.

LncRNA TDRKH-AS1 promotes breast cancer progression via the miR-134-5p/CREB1 axis

BACKGROUND

Breast cancer (BC) is a prevalent malignancy with complex etiology and varied clinical behavior. Long non-coding RNAs (lncRNAs) have emerged as key regulators in cancer progression, including BC. Among these, lncRNA TDRKH-AS1 has been implicated in several cancers, but its role in BC remains unclear.

METHODS

We conducted a comprehensive investigation to elucidate the role of TDRKH-AS1 in BC. Clinical samples were collected from BC patients, and BC cell lines were cultured. Bioinformatics analysis using the starBase database was carried out to assess TDRKH-AS1 expression levels in BC tissue samples. Functional experiments, including knockdown, colony formation, CCK-8, Transwell, and wound-healing assays, were conducted to determine the role of TDRKH-AS1 in BC cell proliferation and invasion. Luciferase reporter and RIP assays were used to examine the interactions between TDRKH-AS1 and miR-134-5p. In addition, the downstream target gene of miR-134-5p, cAMP response element-binding protein 1 (CREB1), was identified and studied using various methods, including RT-qPCR, immunoprecipitation, and rescue experiments. In vivo experiments using mouse tumor xenograft models were conducted to examine the role of TDRKH-AS1 in BC tumorigenesis.

RESULTS

TDRKH-AS1 was found to be significantly upregulated in BC tissues and cell lines. High TDRKH-AS1 expression correlated with advanced BC stages and worse patient outcomes. Knockdown of TDRKH-AS1 led to decreased BC cell proliferation and invasion. Mechanistically, TDRKH-AS1 acted as a sponge for miR-134-5p, thereby reducing the inhibitory effects of miR-134-5p on CREB1 expression. Overexpression of CREB1 partially rescued the effects of TDRKH-AS1 knockdown in BC cells. In vivo studies further confirmed the tumor-promoting role of TDRKH-AS1 in BC.

CONCLUSIONS

Our study unveiled a novel regulatory axis involving TDRKH-AS1, miR-134-5p, and CREB1 in BC progression. TDRKH-AS1 functioned as an oncogenic lncRNA by promoting BC cell proliferation and invasion through modulation of the miR-134-5p/CREB1 axis. These findings highlighted TDRKH-AS1 as a potential diagnostic biomarker and therapeutic target for BC treatment.

The Emerging Roles of Exosomal miRNAs in Breast Cancer Progression and Potential Clinical Applications

Breast cancer remains the leading malignancy in terms of morbidity and mortality today. The tumor microenvironment of breast cancer includes multiple cell types, secreted proteins, and signaling components such as exosomes. Among these, exosomes have a lipid bilayer structure. Exosomes can reflect the biological traits of the parent cell and carry a variety of biologically active components, including proteins, lipids, small molecules, and non-coding RNAs, which include miRNA, lncRNA, and circRNA. MiRNAs are a group of non-coding RNAs of approximately 20-23 nucleotides in length encoded by the genome, triggering silencing and functional repression of target genes. MiRNAs have been shown to play a significant role in the development of cancer owing to their role in the prognosis, pathogenesis, diagnosis, and treatment of cancer. MiRNAs in exosomes can serve as effective mediators of information transfer from parental cells to recipient cells and trigger changes in biological traits such as proliferation, invasion, migration, and drug resistance. These changes can profoundly alter the progression of breast cancer. Therefore, here, we systematically summarize the association of exosomal miRNAs on breast cancer progression, diagnosis, and treatment in the hope of providing novel strategies and directions for subsequent breast cancer treatment.

Comparison Study of Small Extracellular Vesicle Isolation Methods for Profiling Protein Biomarkers in Breast Cancer Liquid Biopsies

Small extracellular vesicles (sEVs) are an important intercellular communicator, participating in all stages of cancer metastasis, immunity, and therapeutic resistance. Therefore, protein cargoes within sEVs are considered as a superior source for breast cancer (BC) biomarker discovery. Our study aimed to optimise the approach for sEV isolation and sEV proteomic analysis to identify potential sEV protein biomarkers for BC diagnosis. sEVs derived from BC cell lines, BC patients' plasma, and non-cancer controls were isolated using ultracentrifugation (UC), a Total Exosome Isolation kit (TEI), and a combined approach named UCT. In BC cell lines, the UC isolates showed a higher sEV purity and marker expression, as well as a higher number of sEV proteins. In BC plasma samples, the UCT isolates showed the highest proportion of sEV-related proteins and the lowest percentage of lipoprotein-related proteins. Our data suggest that the assessment of both the quantity and quality of sEV isolation methods is important in selecting the optimal approach for the specific sEV research purpose, depending on the sample types and downstream analysis.

Emerging functions and clinical applications of exosomal microRNAs in diseases

Exosomes are an important group of extracellular vesicles that transfer several kinds of biomolecules and facilitate cell-cell communication. The content of exosomes, particularly the amounts of microRNA (miRNAs) inside these vesicles, demonstrates a disease-specific pattern reflecting pathogenic processes and may be employed as a diagnostic and prognostic marker. miRNAs may enter recipient cells through exosomes and generate a RISC complex that can cause degradation of the target mRNAs or block translation of their corresponding proteins. Therefore, exosome-derived miRNAs constitute an important mechanism of gene regulation in recipient cells. The miRNA content of exosomes can be used as an important tool in the detection of diverse disorders, particularly cancers. This research field has an important situation in cancer diagnosis. In addition, exosomal microRNAs offer a great deal of promise in the treatment of human disorders. However, there are still certain challenges to be resolved. The most important challenges are as follow: the detection of exosomal miRNAs should be standardized, exosomal miRNAs-associated studies should be conducted in large number of clinical samples, and experiment settings and detection criteria should be consistent across different labs. The goal of this article is to present an overview of the effects of exosome-derived microRNAs on a variety of diseases, including gastrointestinal, pulmonary, neurological, and cardiovascular diseases, with a particular emphasis on malignancies.

Dynamic Role of Exosome microRNAs in Cancer Cell Signaling and Their Emerging Role as Noninvasive Biomarkers

Exosomes are extracellular vesicles that originate from endosomes and are released by all cells irrespective of their origin or type. They play an important role in cell communication and can act in an autocrine, endocrine, or paracrine fashion. They are 40-150 nm in diameter and have a similar composition to the cell of origin. An exosome released by a particular cell is unique since it carries information about the state of the cell in pathological conditions such as cancer. miRNAs carried by cancer-derived exosomes play a multifaceted role by taking part in cell proliferation, invasion, metastasis, epithelial-mesenchymal transition, angiogenesis, apoptosis, and immune evasion. Depending on the type of miRNA that it carries as its cargo, it can render cells chemo- or radiosensitive or resistant and can also act as a tumor suppressor. Since the composition of exosomes is affected by the cellular state, stress, and changes in the environment, they can be used as diagnostic or prognostic biomarkers. Their unique ability to cross biological barriers makes them an excellent choice as vehicles for drug delivery. Because of their easy availability and stability, they can be used to replace cancer biopsies, which are invasive and expensive. Exosomes can also be used to follow the progression of diseases and monitor treatment strategies. A better understanding of the roles and functions of exosomal miRNA can be used to develop noninvasive, innovative, and novel treatments for cancer.

miR-3133 is an unfavorable prognosis factor and tumor suppressor in colon cancer

Dysregulated miRNAs have been demonstrated to be associated with the progression of colon cancer. The dysregulation of miR-3133 was observed in colon cancer, but its specific function was unclear. The functional role of miR-3133 in colon cancer was investigated in this study. A total of 113 colon cancer patients were included. miR-3133 expression was evaluated by PCR. The biological effects of miR-3133 in colon cancer cells were assessed with the help of the transwell and CCK8 assay. The prognostic value of miR-3133 was estimated by a series of statistical analyses. In mechanism, the interaction between miR-3133 and RUFY3 was evaluated by luciferase reporter. The significant downregulation of miR-3133 was observed in colon cancer, which showed a significant association with the advanced TNM stage and bad survival of patients. miR-3133 and TNM stage were identified as independent prognostic indicators of colon cancer. In vitro, the overexpression of miR-3133 exerted a dramatically inhibitory effect on cellular processes of colon cancer, which were enhanced by miR-3133 knockdown. Additionally, miR-3133 could negatively regulate the luciferase activity and expression of RUFY3, which was speculated as the underlying mechanism mediating the regulatory effect of miR-3133. miR-3133 functioned as a prognostic biomarker indicating the progression and prognosis of colon cancer, and it also served as a tumor suppressor via negatively regulating RUFY3, which provides a potential therapeutic target for colon cancer.

Proteomics-based investigation of cerebrovascular molecular mechanisms in cerebral amyloid angiopathy by the FFPE-LMD-PCT-SWATH method

Background

Cerebral amyloid angiopathy (CAA) occurs in 80% of patients with Alzheimer’s disease (AD) and is mainly caused by the abnormal deposition of Aβ in the walls of cerebral blood vessels. Cerebrovascular molecular mechanisms in CAA were investigated by using comprehensive and accurate quantitative proteomics.

Methods

Concerning the molecular mechanisms specific to CAA, formalin-fixed paraffin-embedded (FFPE) sections were prepared from patients having AD neuropathologic change (ADNC) with severe cortical Aβ vascular deposition (ADNC +/CAA +), and from patients having ADNC without vascular deposition of Aβ (ADNC +/CAA −; so called, AD). Cerebral cortical vessels were isolated from FFPE sections using laser microdissection (LMD), processed by pressure cycling technology (PCT), and applied to SWATH (sequential window acquisition of all theoretical fragment ion spectra) proteomics.

Results

The protein expression levels of 17 proteins in ADNC +/CAA +/H donors (ADNC +/CAA + donors with highly abundant Aβ in capillaries) were significantly different from those in ADNC +/CAA − and ADNC −/CAA − donors. Furthermore, we identified 56 proteins showing more than a 1.5-fold difference in average expression levels between ADNC +/CAA + and ADNC −/CAA − donors, and were significantly correlated with the levels of Aβ or Collagen alpha-2(VI) chain (COL6A2) (CAA markers) in 11 donors (6 ADNC +/CAA + and 5 ADNC −/CAA −). Over 70% of the 56 proteins showed ADNC +/CAA + specific changes in protein expression. The comparative analysis with brain parenchyma showed that more than 90% of the 56 proteins were vascular-specific pathological changes. A literature-based pathway analysis showed that 42 proteins are associated with fibrosis, oxidative stress and apoptosis. This included the increased expression of Heat shock protein HSP 90-alpha, CD44 antigen and Carbonic anhydrase 1 which are inhibited by potential drugs against CAA.

Conclusions

The combination of LMD-based isolation of vessels from FFPE sections, PCT-assisted sample processing and SWATH analysis (FFPE-LMD-PCT-SWATH method) revealed for the first time the changes in the expression of many proteins that are involved in fibrosis, ROS production and cell death in ADNC +/CAA +  (CAA patients) vessels. The findings reported herein would be useful for developing a better understanding of the pathology of CAA and for promoting the discovery and development of drugs and biomarkers for CAA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-022-00351-x.

miR-134-5p inhibits osteoclastogenesis through a novel miR-134-5p/Itgb1/MAPK pathway

Osteoporosis affects approximately 200 million people and severely affects quality of life, but the exact pathological mechanisms behind this disease remain unclear. Various miRNAs have been shown to play a predominant role in the regulation of osteoclast formation. In this study, we explored the role of miR-134-5p in osteoclastogenesis both in vivo and in vitro. We constructed an ovariectomized (OVX) mouse model and performed microarray analysis using bone tissue from OVX mice and their control counterparts. Quantitative RT-PCR data from bone tissue and bone marrow macrophages (BMMs) confirmed the decreased expression of miR-134-5p in OVX mice observed in microarray analysis. In addition, a decrease in miR-134-5p was also observed during induced osteoclastogenesis of BMMs collected from C57BL/6N mice. Through transfection with miR-134-5p agomirs and antagomirs, we found that miR-134-5p knockdown significantly accelerated osteoclast formation and cell proliferation and inhibited apoptosis. Furthermore, a luciferase reporter assay showed that miR-134-5p directly targets the integrin surface receptor gene Itgb1. Cotransfection with Itgb1 siRNA reversed the effect of the miR-134-5p antagomir in promoting osteoclastogenesis. Moreover, the abundance levels of MAPK pathway proteins phosphorylated-p38 (p-p38) and phosphorylated-ERK (p-ERK) were significantly increased after transfection with the miR-134-5p antagomir but decreased after transfection with the miR-134-5p agomir or Itgb1 siRNA, which indicated a potential relationship between the miR-134-5p/Itgb1 axis and the MAPK pathway. Collectively, these results revealed that miR-134-5p inhibits osteoclast differentiation of BMMs both in vivo and in vitro and that the miR-134-5p/Itgb1/MAPK pathway might be a potential target for osteoporosis therapy.

Developmental venous anomalies are a genetic primer for cerebral cavernous malformations

Cerebral cavernous malformations (CCM) are a neurovascular anomaly that may occur sporadically, or be inherited due to autosomal dominant mutations in KRIT1 , CCM2 , or PDCD10 . Individual lesions are caused by somatic mutations which have been identified in KRIT1, CCM2, PDCD10, MAP3K3, and PIK3CA . However, the interactions between mutations, and their relative contributions to sporadic versus familial cases remain unclear. We show that mutations in KRIT1, CCM2, PDCD10, and MAP3K3 are mutually exclusive, but may co-occur with mutations in PIK3CA. We also find that MAP3K3 mutations may cause sporadic, but not familial CCM. Furthermore, we find identical PIK3CA mutations in CCMs and adjacent developmental venous anomalies (DVA), a common vascular malformation frequently found in the vicinity of sporadic CCMs. However, somatic mutations in MAP3K3 are found only in the CCM. This suggests that sporadic CCMs are derived from cells of the DVA which have acquired an additional mutation in MAP3K3 .

The role of Exosomal miRNAs in cancer

Exosomal miRNAs have attracted much attention due to their critical role in regulating genes and the altered expression of miRNAs in virtually all cancers affecting humans (Sun et al. in Mol Cancer 17(1):14, 2018). Exosomal miRNAs modulate processes that interfere with cancer immunity and microenvironment, and are significantly involved in tumor growth, invasion, metastasis, angiogenesis and drug resistance. Fully investigating the detailed mechanism of miRNAs in the occurrence and development of various cancers could help not only in the treatment of cancers but also in the prevention of malignant diseases. The current review highlighted recently published advances regarding cancer-derived exosomes, e.g., sorting and delivery mechanisms for RNAs. Exosomal miRNAs that modulate cancer cell-to-cell communication, impacting tumor growth, angiogenesis, metastasis and multiple biological features, were discussed. Finally, the potential role of exosomal miRNAs as diagnostic and prognostic molecular markers was summarized, as well as their usefulness in detecting cancer resistance to therapeutic agents.