|Year : 2017 | Volume
| Issue : 5 | Page : 167-173
Role of exosome microRNA in breast cancer
Wang Qu, Ma Fei, Binghe Xu
Department of Medical Oncology, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
|Date of Submission||11-Apr-2017|
|Date of Acceptance||29-Sep-2017|
|Date of Web Publication||26-Oct-2017|
Department of Medical Oncology, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Panjiayuannanli 17, Chaoyang District, Beijing 100021
Source of Support: None, Conflict of Interest: None
Exosomes are nanovesicles derived from multiple cell types and could be isolated from various bodily fluids, such as blood and saliva. The molecular contents of exosomes have been proved to reflect their parent cell origins. MicroRNA (miRNA), a large family of small, noncoding RNAs, is enriched in exosomes and could regulate the expression of their target genes. Numerous studies have indicated that aberrant expression level of exosomal miRNAs is closely related to the onset of multiple diseases, including cancer. For example, the studies show that tumorigenesis, drug resistance, invasiveness, and metastasis in breast cancer, are partly mediated by exosome miRNAs, functioning as tools for cell-to-cell communication. Furthermore, several investigations have revealed the immense potential of exosome miRNAs to serve as prognostic and diagnostic biomarkers, whereas certain miRNAs could even be on the target list of novel therapies for cancer, including breast cancer. Due to the lack of a standard approach, exosome miRNAs have not been successfully made into clinical practice, yet. In this review, we highlight the major progressions in exosome miRNA research on breast cancer and the current limitations/challenges in its clinical implementation. Promising and potential applications of exosomal miRNAs will also be addressed.
Keywords: Breast cancer, exosome, microRNA
|How to cite this article:|
Qu W, Fei M, Xu B. Role of exosome microRNA in breast cancer. Cancer Transl Med 2017;3:167-73
| Introduction|| |
As the most prevalent type of cancer in women, breast cancer was responsible for approximately seventy thousand cancer-related deaths in China in 2015, and the upward trend in the occurrence of the breast cancer would not change in a short time. Due to the prominent heterogeneity, breast cancer could be classified into various subtypes based on the distinct gene expression profile. Further, the molecular mechanism of breast cancer development may be the determinant of the effects of various therapies., Recent studies have well established a close relation of exosomes and the encapsulated microRNA (miRNA) with the pathogenesis and prognosis of breast cancer., Thus exosome miRNA may be of value as an early diagnostic tool and as a therapeutic target in breast cancer. In this review, we summarize the current progression in exosome miRNA research, exclusive to breast cancer.
| Exosome|| |
The term “exosome” was first coined by Johnstone in 1987, to describe the vesicles containing unwanted proteins discarded in the transition from reticulocytes to mature erythrocytes. Subsequent studies discovered that exosomes possess more sophisticated functions and could be secreted by several types of cells including dendritic cells, stem cells, and endothelial cells,,, which remarkably expanded the scope of exosomes. Currently, exosomes are defined as small nanovesicles, with a size about 30–100 nm, released from the fusion process between the plasma membrane and the late endocytic compartment (also called multivesicular endosome)., What's more, emerging evidence shows that exosomes are widely distributed in blood, urine, ascites, cerebrospinal fluid and may even exist in all body fluid in eukaryotes.,
In studies focused on exosome compositions, centrifugation, and purification demonstrated that exosomes are phospholipid bilayer vesicles containing numerous molecular constituents, such as proteins and nucleic acids, of their parent cell.,,, Exosomes are enriched in chaperones, cytoskeletal proteins, and fusion-associated proteins as tetraspanins (CD9, CD63, CD81, and CD82), annexins, and flotillin. Besides, heat-shock protein, phosphatase, and tensin homolog (PTEN) and several other proteins that are closely related with tumor development, also extensively reside in the lumen of exosome., The major nucleic acids transported through exosome include mRNA, miRNA, and siRNA, which function in protein expression, regulate translation, and gene silencing, respectively.,,
The release and trafficking of exosomes are regulated by several proteins. Ostrowski et al. showed that Rab27a and Rab27b were associated with exosome secretion in HeLa cells. The tumor suppressor protein p53 and its downstream effector TSAP6 were also identified by Yu et al. as enhancers of exosome production. Koumangoye et al. observed that annexins could influence the process of exosome uptake and internalization in BT-549 cells, a breast carcinoma cell line. All these studies indicate that the formation and secretion of exosomes are regulated by a complicated molecular network, the detailed mechanism of which is yet to be unveiled.
| MicroRNA|| |
Given the fact that exosomes contain proteins, lipids, and RNAs, they are thus able to carry complex biological information. Therefore, it is not difficult to understand that they have been involved in a variety of physiological and pathological conditions. A number of studies have demonstrated that miRNAs are crucial in these conditions. miRNAs are evolutionally conserved small non-coding RNAs, containing 21-25 nucleotides. Initially, they are mainly transcribed by RNA polymerase II to form the primary transcripts called pri-miRNAs. Then pri-miRNAs are further processed into mature miRNAs by two RNase III enzymes, Drosha and Dicer. These mature miRNAs are finally incorporated into the RNA-induced silencing complex (RISC) with Argonaute proteins. As a part of this complex, mature miRNA could regulate target gene expression at the posttranscriptional level through mRNA degradation or translation disruption. miRNAs are responsible for the regulation of up to one-third of genes in the human genome and have recently been identified as key players in various cellular processes. Since breast cancer is the most frequently-diagnosed life-threatening cancer in women, there is a surge of studies focused on dysregulation of miRNAs in it. Increased evidence shows that the serum levels of several miRNAs, such as miR-195, differ between healthy individuals and breast cancer patients. However, it is hard to reach an agreement for circulating miRNAs profiles as reliable biomarkers, potentially due to the inherent heterogeneity of the miRNA populations in blood. The miRNAs packed in exosome are found more stable than circulating miRNAs, maybe partially due to the robust bilayer structure which enables efficient storage and recovery in conditions that would normally degrade free miRNAs. Some investigators also discovered that exosomes were highly enriched with miRNAs. Maybe, there is a hypothetical selective sorting mechanism can control the incorporation of miRNAs, which may explain the efficient enclosure of majority of miRNAs into exosomes, instead of freely circulating in human biologic fluids., Based on the above properties, exosome enclosed miRNA may have better clinical implementation in the future than free miRNA. In fact, a number of exosome miRNAs have already been identified as critical regulators in breast cancer [Figure 1] and [Table 1].
|Figure 1: Biological process mediated by exosome microRNAs in breast cancer|
Click here to view
| Exosome MicroRNA and Breast Cancer Tumorigenesis|| |
Recent studies confirm that exosomes derived from cancer cells play a pro-tumorigenic role by a horizontal transfer of mRNA and pro-angiogenic proteins. The miR-138 is shown to take part in the development of thyroid carcinoma, whereas there are not many reports on the role that specific exosome derived miRNA plays in breast cancer. One study demonstrated that RISC-associated miRNAs from breast cancer exosomes could mediate significant transcriptome alterations in recipient cells. These miRNAs may exert an oncogenic “field effect” to convert nontumorigenic cells into tumor-forming cells. Still, further studies are required to address such implication and clarify the possible miRNAs.
| Exosome MicroRNA and Breast Cancer Metastasis|| |
Three miRNAs, miR-21, miR-378e, and miR-143, were identified with an increased level in exosomes from cancer-associated fibroblasts (CAFs), compared to those from normal fibroblasts, during differential expression profile analysis. After exposure to CAF exosomes or transfection with these miRNAs, the BT549, MDA-MB-231, and T47D breast cancer cell lines exhibited anchorage-independent cell growth, as well as a notably enhanced capacity to form mammospheres. A change in stemness phenotype of breast cancer cells was also observed, as the stem cell and epithelial-mesenchymal transition markers increased.
In addition to serving as an important diagnostic tool for breast cancer, miRNA is found to be involved in almost all aspects of breast cancer progression, as evidenced in a number of published studies., Despite being treated with hormonal and/or chemotherapeutic agents, nearly half of the patients show distant metastasis, resulting in poor prognosis, with a median survival of 1–2 years and a 5-year survival rate of approximately 20%. Thus, it is important to identify exosome miRNAs associated with metastasis to provide a reliable diagnostic tool for clinicians to assess disease stage and monitor progression. Research in exosome miRNA derived from breast cancer cell lines with brain metastasis elucidated an upregulation in miRNA-210 and downregulation in miR-19a and miR-29c in comparison with nonbrain metastatic breast cancer cell lines. This may represent the expression profile for metastasis to the brain or may simply function as a common marker for metastasis. What's more, exosome miRNA markers for metastasis may give an insight into the molecular mechanisms of metastasis, which would help in efficient treatment formulation. For example, miR-10b is expressed at a higher level in metastatic breast cancer MDA-MB-231 cells than in nonmetastatic breast cancer cells and normal breast cells. Furthermore, miR-10b derived from metastatic MDA-MB-231 cells is found packed in exosomes and is actively secreted into the medium. Pertaining to its ability to suppress protein expression of HOXD10 and KLF4 genes, involved in regulating cell invasion, on ingestion, the miR-10b packed exosomes could induce invasion in otherwise nonmalignant HMLE breast cancer cell. Accumulating evidence have shown that miR-9, which was also found to be packaged into microvesicles and secreted by several human tumor cell lines for the direct delivery to endothelial cells, could promote migration and neovascularization by activating JACK–STAT pathway in endothelial cells. The result was verified by Baroni et al. who also demonstrated that through the delivery of miR-9 mediated by exosomes, tumor cells could modulate gene expression profile and induce the CAF-like phenotype in recipient fibroblasts. In addition, miR-9 is shown to function as a sort of “signal” to promote endothelial cell proliferation and convert the microenvironment into a tumorigenic niche. The specific mechanism may involve the reduction of E-cadherin, a calcium-dependent, cell–cell adhesion glycoprotein, which also has been demonstrated as a direct target of miR-9. Another miRNA with similar activity is miR-939, which directly targets VE-cadherin, another adhesion glycoprotein involved in vascular permeability. The study showed that miR939 could lead to increased permeability in human umbilical vascular endothelial cells, in vitro. In addition, treating HUVEC cells with miR-939 packaged exosomes, released from miR-939-mimic transfected MDA-MB-231 cells, disrupted the endothelial barrier favoring transendothelial migration of MDA-MB-231 cells. Furthermore, Yang et al. studied the breast cancer cells cocultivated with tumor-associated macrophages (TAMs) and found that TAMs promote the invasion of breast cancer cells through exosome-mediated delivery of oncogenic miR-233. Another couple of studies identified miR-223's role in enhancing the invasiveness of breast cancer cells, by targeting the Mef2c-b-catenin pathway., A study investigating the metastatic breast cancer cells revealed that cancer-secreted miR-105 exosome induced vascular permeability and metastasis to distant organs by targeting ZO-1, a central molecular component in tight junctions, thus efficiently destroying the integrity of these natural barriers. What's more significant is that miR-105 has already been detected in the circulation in early-stage breast cancer patients, and treatment with anti-miR-105 showed a potential therapeutic effect by maintaining the vascular integrity in tumor-bearing animals. Further, a study showed that breast cancer cells could induce metastasis by suppressing the glucose uptake in nontumor cells, within premetastatic niche, through secreting exosomes containing high level of miR-122. Inhibition of miR-122 could restore glucose uptake in distant organs in vivo, including brain and lungs, while decreasing the incidence of metastasis. In conclusion, these findings indicate that breast cancer exosome miRNAs may have the potential to serve as the blood-based personalized diagnostic markers and therapeutic targets in patients with more aggressive breast cancers.
| Exosome MicroRNA and Breast Cancer Drug Resistance|| |
Although there is a significant increase in the development of new therapeutics for breast cancer in the past two decades, resistance to these therapeutics has become a growing problem. Resistance can be either de novo or acquired along the disease progression, with studies reporting an increase in the incidence of such resistance to therapeutics. To date, more and more evidence shows that the dysregulation of miRNAs packed in exosome is closely related to the acquisition of drug resistance in breast cancer. A recent research showed that the exosomes from drug-resistant breast cancer cells served as messengers in intercellular communication by transferring miRNAs to establish their regulatory role in conferring drug resistance. As a hallmark of cancer, hypoxia can induce resistance in tumors to chemotherapy and radiotherapy, which is an important consideration in cancer diagnosis and therapeutic design. One study discovered that hypoxic breast cancer cells could transfer miR-210 through exosomes to neighboring cells, either surrounding cancer cells or neighboring stromal cells, bothin vitro and in vivo. Downstream analysis elucidated that the target genes of miR-210 were related to vascular remodeling, such as Ephrin A3 and PTP1B, thus promoting angiogenesis. These results indicate that exosome miRNAs spread from hypoxic cancer cells to adjacent cancer cells to create a more favorable microenvironment for tumor survival. Moreover, direct transmission of drug resistance was reported in adriamycin-resistant variant of Michigan Cancer Foundation-7 (MCF-7) breast cancer cell line-MCF-7/Adr, developed from the adriamycin-sensitive variant (MCF-7/S). After coculture with exosomes from drug-resistant variant MCF-7/Adr (A/exo), MCF-7/S cells demonstrably acquired drug resistance, whereas the same change was not observed in the cells treated with exosomes from drug-sensitive variant MCF/7/S (S/exo). Further, looking for distinct differences, miRNA profiling of A/exo-treated and S/exo-treated MCF-7/S cells identified miR-222, whose quantity was significantly greater in A/exo-treated group. Adriamycin resistance was also acquired in MCF-7/S cells transfected with miR-222 mimics. The mechanism of miR-222 mediated adriamycin-resistance in MCF-7 cells may lie in the reduction of the PTEN activity, a negative regulator of the PI3K/Akt pathway. In addition to adriamycin, another study revealed the induced-resistance against tamoxifen in MCF-7 wild-type cells, through transmission of miR-221/222 packaged exosomes released from tamoxifen-resistant MCF-7 cell line. Increased expression of miR-221/222 in recipient cells could be a potential signature of tamoxifen resistance, as miR-221/222 functions as an oncogene in breast cancer by targeting the cell cycle inhibitor p27Kip1, and thus promoting cell proliferation. The elevated miR-221/222 contributes to tamoxifen resistance by effectively reducing the expression of ERα target genes. In addition to exosome miRNA content of breast cancer cells, investigators also monitored the level of exosome miRNA in breast tissues from breast cancer patients, both before and after chemotherapy. They demonstrated that a variety of exosome miRNA profiles including miR-4443 were significantly altered in both cells and tissues after chemotherapy. Subsequent target gene prediction and GO and KEGG enrichment analysis of these miRNAs demonstrated that many miRNAs had specific target genes associated with PI3K-Akt, Wnt, and mTOR signal pathways,,,, and these signal pathways have been confirmed to be involved in drug resistance and treatment failure., In general, exosome miRNA associated with drug resistance may serve as potential targets for novel treatments and facilitate the development of new therapeutic agents or function as adjuvants to current therapies to restore sensitivity.
| Exosome MicroRNA and Breast Cancer Diagnosis|| |
Currently, several studies have deeply analyzed miRNA expression profiles in exosomes using malignant mammary epithelial cell lines MDA-MB-231, MDA-MB-436, and the nontumorigenic mammary epithelial cell line MCF10A. Difference in the miRNA profiles of malignant and nonmalignant mammary epithelial cells are also discovered. The findings have been extended to human cancer by investigating studies performed in cancer patients. Certain miRNA species, such as miR-101 and miR-372, are observed at remarkably increased levels in the serum of breast cancer patients, than the healthy controls. Work carried out by Hannafon et al. has demonstrated that miR-21 and miR-1246 were also selectively enriched in human breast cancer exosomes, and thereby in the plasma. Moreover, expression profiling in breast cancer, which is a highly heterogeneous disease with phenotypically different tumor subtypes, also shows that a number of miRNAs are associated with molecular subtypes of breast cancer., For instance, the serum level of exosome miR-373 was elevated in ER-negative and PR-negative breast cancer patients when compared with the corresponding receptor-positive patients. The mechanism behind this association was considered to be the miR-373 mediated downregulation of ER protein expression. Since miRNAs in exosomes reflect their parent breast cancer cells, the presence of breast tumor could be potentially recognize and its subtype could be subsequently stratified. Such potential of subtype discrimination may be of particular value in the clinical setting given the fact that survival from breast cancer differs significantly between subtypes.
| Exosome MicroRNA with Therapeutic Potential|| |
Accumulating evidence indicates that miR-16, a mesenchymal stem cell derived miRNA known to regulate vascular endothelial growth factor (VEGF), could exert anti-angiogenic effect inin vitro andin vivo carcinogenic models. Thus, mesenchymal stem cell-derived exosomes could significantly suppress the expression of VEGF in tumor cells. Supporting evidence was also obtained in the study performed by Jang et al. who demonstrated that epigallocatechin-3-gallate, a tumor inhibitor, could upregulate miR-16 in breast cancer cells, which when transferred to TAM through exosomes, could inhibit TAM infiltration and polarization of M2 macrophages, both of which favor tumor progression through nuclear factor-κB pathway. Further, exposing endothelial cells to exosomes from DHA-treated breast cancer cells resulted in overexpression of miR-23b and miR-320b, whereas decreasing the expression of their target pro-angiogenic genes (PLAU, AMOTL1, NRP1, and ETS2)., Thus, tube formation by endothelial cells was remarkably suppressed, indicating that the miRNAs carried in exosomes mediate DHA's anti-angiogenic action. In another model proposed by Nicolas et al., endothelial cells exposed to chemotherapy or radiotherapy could release miR-503-loaded exosomes into the adjacent environment, which might restrain tumor growth by directly regulating tumor cell proliferation and invasion, accomplished through CCND2, and CCND3 inhibition. Keith et al. investigated an aggressive clonal TNBC cell variant Hs578Ts(i)8, the miRNA profiling of which revealed a substantial downregulation of exosome miR-134. Functional studies further indicated that it significantly downregulated STAT5B, thus controlling Hsp90 and Bcl-2 levels, which finally resulted in reduced cellular proliferation and enhanced cisplatin-induced apoptosis. Furthermore, delivering miR-134-enriched exosomes could decrease cellular migration and invasion, but improve their sensitivity to anti-Hsp90 drugs, in Hs578Ts (i) 8 cells.
The exosomes released from the tumor microenvironment may serve as a significant mediator of cell-to-cell communication, which can also be exploited to inhibit tumor pathogenesis by transferring antitumor molecules. Interestingly, even tumor cells themselves could deliver antitumor therapeutic miRNAs packed in exosomes. All these therapeutic potentials indicate that besides the function as biomarkers, the regulation of the expression of multiple genes makes the modulation of miRNA activity a promising approach for cancer treatment.
| Limitations of Exosome MicroRNA|| |
Although studies in the exosome field have exploded in recent years, there is still no standard procedure established for exosome studies. For example, serum, plasma, and even whole blood have all been utilized as starting materials in studies, but it is still uncertain that which fraction of blood is ideal for exosome isolation and further investigation. Hopefully, the rapidly emerging methods in the field of exosome isolation and analysis will address the issue. Owing to the location of miRNA genes, frequently mapping to fragile chromosomal regions, expression is frequently changed in those unstable genomic regions, which makes it difficult to rule out the possibility that different miRNA abundance may result from different isolation and quantification techniques, even from different vendors of the same platform. Thus, the current data are not comparable due to the heterogeneity of methodologies, making it hard to go a step further to assess their clinical practicality at present. What's more, plasma exosome populations may have diverse cell origins as mentioned in the beginning. They are heterogeneous, especially influenced by blood cells, and the sensitivity and specificity for detecting cancer are not yet satisfactory. Hence, circulating exosome miRNA may still not be a superior choice compared to circulating miRNA analysis at this moment. Moreover, because of multiple critical roles played by exosomal miRNAs in regulation of tumor initiation, metastasis, and chemoresistance, strong variation has already been noted in different situations. For example, a cancer-specific elevation in serum miR-101 appeared in breast cancer patients, in contrast with patients with benign breast disease and healthy individuals. However, in lymph node-negative breast cancer patients, an opposite result implicated that miR-101 may play a dual role in breast cancer. Similar results for miR-101 were also obtained in the comparison of estradiol (E2)-independent and -dependent breast cancer growth. In normal E2-containing medium, miR-101 suppressed cell growth while it promoted cell growth in medium without E2. Such phenomenon may yield since estrogen deprivation significantly enhanced the activation of Akt signaling pathway mediated by miR-101, finally resulting in malignant transformation, invasiveness, and metastasis. Diverse roles for a single exosomal miRNA, such as miR-101, would create huge barriers for further analysis and application. Conversely, as plasma exosome populations are heterogeneous and may come from any types of cells, dysregulation of the same exosomal miRNA could also be seen in different tumors. Like miR-21, which is considered as an oncogenic miRNA, is confirmed to be overexpressed in both male and female invasive breast cancer compared to normal breast tissue, whereas differential expression of serum miR-21 has been previously identified in circulating exosomes from patients with lung cancer and melanoma as well., Thus, patient comorbidities could not be overlooked as they also impact miRNA level to some degree, and may lead to the lack of specificity for breast cancer. To distinguish such difference, it is necessary to examine the exosomal fraction in detail and to identify different tumor origins. In this regard, a tumor-exosomal marker protein to specifically represent breast cancer is still on the search.
| Conclusion|| |
To sum up, many groups have studied exosome miRNA in breast cancer cell lines, human tumor-bearing mice, and breast cancer patients, indicating its functional significance. Despite these efforts, researchers are still trying to fully characterize the exosome miRNA content of breast cancer cells or examine the levels of miRNAs in circulating exosomes from patients with breast cancer. Nevertheless, novel efforts in the context of identifying distinct molecular subtypes of breast cancer have a great potential in clinical applications. Considering the advantages of blood-based “liquid biopsies” over tissue biopsies, convenient screening for miRNAs in large scale could come true. Combined with the characteristics of miRNAs, plenty of valuable information for noninvasive cancer diagnosis, subtype specification and therapy, prediction and surveillance, as well as designing of novel therapeutic agents could be achieved, and hopefully in the near future.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
DeSantis CE, Fedewa SA, Goding Sauer A, Kramer JL, Smith RA, Jemal A. Breast cancer statistics, 2015: Convergence of incidence rates between black and white women. CA Cancer J Clin
2016; 66 (1): 31–42.
Chen W, Zheng R, Baade PD, Zhang S, Zeng H, Bray F, Jemal A, Yu XQ, He J. Cancer statistics in China, 2015. CA Cancer J Clin
2016; 66 (2): 115–32.
Perou CM, Sørlie T, Eisen MB, van de Rijn M, Jeffrey SS, Rees CA, Pollack JR, Ross DT, Johnsen H, Akslen LA, Fluge O, Pergamenschikov A, Williams C, Zhu SX, Lønning PE, Børresen-Dale AL, Brown PO, Botstein D. Molecular portraits of human breast tumours. Nature
2000; 406 (6797): 747–52.
Rouzier R, Perou CM, Symmans WF, Ibrahim N, Cristofanilli M, Anderson K, Hess KR, Stec J, Ayers M, Wagner P, Morandi P, Fan C, Rabiul I, Ross JS, Hortobagyi GN, Pusztai L. Breast cancer molecular subtypes respond differently to preoperative chemotherapy. Clin Cancer Res
2005; 11 (16): 5678–85.
Valentin MD, da Silva SD, Privat M, Alaoui-Jamali M, Bignon YJ. Molecular insights on basal-like breast cancer. Breast Cancer Res Treat
2012; 134 (1): 21–30.
Volinia S, Croce CM. Prognostic microRNA/mRNA signature from the integrated analysis of patients with invasive breast cancer. Proc Natl Acad Sci U S A
2013; 110 (18): 7413–7.
Hoppe R, Achinger-Kawecka J, Winter S, Fritz P, Lo WY, Schroth W, Brauch H. Increased expression of miR-126 and miR-10a predict prolonged relapse-free time of primary oestrogen receptor-positive breast cancer following tamoxifen treatment. Eur J Cancer
2013; 49 (17): 3598–608.
Johnstone RM, Adam M, Hammond JR, Orr L, Turbide C. Vesicle formation during reticulocyte maturation. Association of plasma membrane activities with released vesicles (exosomes). J Biol Chem
1987; 262 (19): 9412–20.
Simpson RJ, Jensen SS, Lim JW. Proteomic profiling of exosomes: Current perspectives. Proteomics
2008; 8 (19): 4083–99.
Andre F, Schartz NE, Movassagh M, Flament C, Pautier P, Morice P, Pomel C, Lhomme C, Escudier B, Le Chevalier T, Tursz T, Amigorena S, Raposo G, Angevin E, Zitvogel L. Malignant effusions and immunogenic tumour-derived exosomes. Lancet
2002; 360 (9329): 295–305.
Thery C, Zitvogel L, Amigorena S. Exosomes: Composition, biogenesis and function. Nat Rev Immunol
2002; 2 (8): 569–79.
Keller S, Sanderson MP, Stoeck A, Altevogt P. Exosomes: From biogenesis and secretion to biological function. Immunol Lett
2006; 107 (2): 102–8.
Friel AM, Corcoran C, Crown J, O'Driscoll L. Relevance of circulating tumor cells, extracellular nucleic acids, and exosomes in breast cancer. Breast Cancer Res Treat
2010; 123 (3): 613–25.
Raposo G, Stoorvogel W. Extracellular vesicles: Exosomes, microvesicles, and friends. J Cell Biol
2013; 200 (4): 373–83.
van der Pol E, Boing AN, Harrison P, Sturk A, Nieuwland R. Classification, functions, and clinical relevance of extracellular vesicles. Pharmacol Rev
2012; 64 (3): 676–705.
Sandvig K, Llorente A. Proteomic analysis of microvesicles released by the human prostate cancer cell line PC-3. Mol Cell Proteomics
2012; 11 (7): M111.012914.
Choi DS, Choi DY, Hong BS, Jang SC, Kim DK, Lee J, Kim YK, Kim KP, Gho YS. Quantitative proteomics of extracellular vesicles derived from human primary and metastatic colorectal cancer cells. J Extracell Vesicles
2012. doi: 10.3402/jev.v1i0.18704.
Guzman N, Agarwal K, Asthagiri D, Yu L, Saji M, Ringel MD, Paulaitis ME. Breast cancer-specific miR signature unique to extracellular vesicles includes “microRNA-like” tRNA fragments. Mol Cancer Res
2015; 13 (5): 891–901.
van den Boorn JG, Dassler J, Coch C, Schlee M, Hartmann G. Exosomes as nucleic acid nanocarriers. Adv Drug Deliv Rev
2013; 65 (3): 331–5.
Raimondo F, Morosi L, Chinello C, Magni F, Pitto M. Advances in membranous vesicle and exosome proteomics improving biological understanding and biomarker discovery. Proteomics
2011; 11 (4): 709–20.
Mathew AB, Johnstone RM. Hsp-70 is closely associated with the transferrin receptor in exosomes from maturing reticulocytes. Biochem J
1995; 308 (Pt 3): 803–30.
Putz U, Howitt J, Doan A, Goh CP, Low LH, Silke J, Tan SS. The tumor suppressor PTEN is exported in exosomes and has phosphatase activity in recipient cells. Sci Signal
2012; 5 (243): ra70.
Lasser C, Eldh M, Lotvall J. Isolation and characterization of RNA-containing exosomes. J Vis Exp
2012; (59): e3037.
Tosar JP, Gambaro F, Sanguinetti J, Bonilla B, Witwer KW, Cayota A. Assessment of small RNA sorting into different extracellular fractions revealed by high-throughput sequencing of breast cell lines. Nucleic Acids Res
2015; 43 (11): 5601–16.
Chen X, Liang H, Zhang J, Zen K, Zhang CY. Secreted microRNAs: A new form of intercellular communication. Trends Cell Biol
2012; 22 (3): 125–32.
Ostrowski M, Carmo NB, Krumeich S, Fanget I, Raposo G, Savina A, Moita CF, Schauer K, Hume AN, Freitas RP, Goud B, Benaroch P, Hacohen N, Fukuda M, Desnos C, Seabra MC, Darchen F, Amigorena S, Moita LF, Thery C. Rab27a and Rab27b control different steps of the exosome secretion pathway. Nat Cell Biol
2010; 12 (1): 19–30.
Yu X, Harris SL, Levine AJ. The regulation of exosome secretion: A novel function of the p53 protein. Cancer Res
2006; 66 (9): 4795–801.
Koumangoye RB, Sakwe AM, Goodwin JS, Patel T, Ochieng J. Detachment of breast tumor cells induces rapid secretion of exosomes which subsequently mediate cellular adhesion and spreading. PLoS One
2011; 6 (9): e24234.
Skokos D, Le Panse S, Villa I, Rousselle JC, Peronet R, David B, Namane A, Mecheri S. Mast cell-dependent B and T lymphocyte activation is mediated by the secretion of immunologically active exosomes. J Immunol
2001; 166 (2): 868–76.
Bartel DP. MicroRNAs: Target recognition and regulatory functions. Cell
2009; 136 (2): 215–33.
Takahashi RU, Miyazaki H, Ochiya T. The roles of microRNAs in breast cancer. Cancers (Basel)
2015; 7 (2): 598–616.
Bartel DP. MicroRNAs: Genomics, biogenesis, mechanism, and function. Cell
2004; 116 (2): 281–97.
Schaefer A, Stephan C, Busch J, Yousef GM, Jung K. Diagnostic, prognostic and therapeutic implications of microRNAs in urologic tumors. Nat Rev Urol
2010; 7 (5): 286–97.
Zhang M, Zhang CG, Ding W. Exosome in cancer diagnosis and treatment. Sheng Li Ke Xue Jin Zhan
2014; 45 (5): 372–8.
Skog J, Wurdinger T, van Rijn S, Meijer DH, Gainche L, Sena-Esteves M, Curry WT Jr., Carter BS, Krichevsky AM, Breakefield XO. Glioblastoma microvesicles transport RNA and proteins that promote tumour growth and provide diagnostic biomarkers. Nat Cell Biol
2008; 10 (12): 1470–6.
Valadi H, Ekstrom K, Bossios A, Sjostrand M, Lee JJ, Lotvall JO. Exosome-mediated transfer of mRNAs and microRNAs is a novel mechanism of genetic exchange between cells. Nat Cell Biol
2007; 9 (6): 654–9.
Gallo A, Tandon M, Alevizos I, Illei GG. The majority of microRNAs detectable in serum and saliva is concentrated in exosomes. PLoS One
2012; 7 (3): e30679.
Melo SA, Sugimoto H, O'Connell JT, Kato N, Villanueva A, Vidal A, Qiu L, Vitkin E, Perelman LT, Melo CA, Lucci A, Ivan C, Calin GA, Kalluri R. Cancer exosomes perform cell-independent microRNA biogenesis and promote tumorigenesis. Cancer Cell
2014; 26 (5): 707–21.
Muralidharan-Chari V, Clancy JW, Sedgwick A, D'Souza-Schorey C. Microvesicles: Mediators of extracellular communication during cancer progression. J Cell Sci
2010; 123 (Pt 10): 1603–11.
Mitomo S, Maesawa C, Ogasawara S, Iwaya T, Shibazaki M, Yashima-Abo A, Kotani K, Oikawa H, Sakurai E, Izutsu N, Kato K, Komatsu H, Ikeda K, Wakabayashi G, Masuda T. Downregulation of miR-138 is associated with overexpression of human telomerase reverse transcriptase protein in human anaplastic thyroid carcinoma cell lines. Cancer Sci
2008; 99 (2): 280–6.
Donnarumma E, Fiore D, Nappa M, Roscigno G, Adamo A, Iaboni M, Russo V, Affinito A, Puoti I, Quintavalle C, Rienzo A, Piscuoglio S, Thomas R, Condorelli G. Cancer-associated fibroblasts release exosomal microRNAs that dictate an aggressive phenotype in breast cancer. Oncotarget
2017; 8 (12): 19592–608.
Iorio MV, Ferracin M, Liu CG, Veronese A, Spizzo R, Sabbioni S, Magri E, Pedriali M, Fabbri M, Campiglio M, Ménard S, Palazzo JP, Rosenberg A, Musiani P, Volinia S, Nenci I, Calin GA, Querzoli P, Negrini M, Croce CM. MicroRNA gene expression deregulation in human breast cancer. Cancer Res
2005; 65 (16): 7065–70.
Harquail J, Benzina S, Robichaud GA. microRNAs and breast cancer malignancy: An overview of miRNA-regulated cancer processes leading to metastasis. Cancer Biomark
2012; 11 (6): 269–80.
Nicolini A, Giardino R, Carpi A, Ferrari P, Anselmi L, Colosimo S, Conte M, Fini M, Giavaresi G, Berti P, Miccoli P. Metastatic breast cancer: An updating. Biomed Pharmacother
2006; 60 (9): 548–56.
Yardley DA. Visceral disease in patients with metastatic breast cancer: Efficacy and safety of treatment with ixabepilone and other chemotherapeutic agents. Clin Breast Cancer
2010; 10 (1): 64–73.
Camacho L, Guerrero P, Marchetti D. MicroRNA and protein profiling of brain metastasis competent cell-derived exosomes. PLoS One
2013; 8 (9): e73790.
Singh R, Pochampally R, Watabe K, Lu Z, Mo YY. Exosome-mediated transfer of miR-10b promotes cell invasion in breast cancer. Mol Cancer
2014; 13: 256.
Gwak JM, Kim HJ, Kim EJ, Chung YR, Yun S, Seo AN, Lee HJ, Park SY. MicroRNA-9 is associated with epithelial-mesenchymal transition, breast cancer stem cell phenotype, and tumor progression in breast cancer. Breast Cancer Res Treat
2014; 147 (1): 39–49.
Baroni S, Romero-Cordoba S, Plantamura I, Dugo M, D'Ippolito E, Cataldo A, Cosentino G, Angeloni V, Rossini A, Daidone MG, Iorio MV. Exosome-mediated delivery of miR-9 induces cancer-associated fibroblast-like properties in human breast fibroblasts. Cell Death Dis
2016; 7 (7): e2312.
Zhuang G, Wu X, Jiang Z, Kasman I, Yao J, Guan Y, Oeh J, Modrusan Z, Bais C, Sampath D, Ferrara N. Tumour-secreted miR-9 promotes endothelial cell migration and angiogenesis by activating the JAK-STAT pathway. EMBO J
2012; 31 (17): 3513–23.
Ma L, Young J, Prabhala H, Pan E, Mestdagh P, Muth D, Teruya-Feldstein J, Reinhardt F, Onder TT, Valastyan S, Westermann F, Speleman F, Vandesompele J, Weinberg RA. miR-9, a MYC/MYCN-activated microRNA, regulates E-cadherin and cancer metastasis. Nat Cell Biol
2010; 12 (3): 247–56.
Di Modica M, Regondi V, Sandri M, Iorio MV, Zanetti A, Tagliabue E, Casalini P, Triulzi T. Breast cancer-secreted miR-939 downregulates VE-cadherin and destroys the barrier function of endothelial monolayers. Cancer Lett
2017; 384: 94–100.
Yang M, Chen J, Su F, Yu B, Su F, Lin L, Liu Y, Huang JD, Song E. Microvesicles secreted by macrophages shuttle invasion-potentiating microRNAs into breast cancer cells. Mol Cancer
2011; 10: 117.
Johnnidis JB, Harris MH, Wheeler RT, Stehling-Sun S, Lam MH, Kirak O, Brummelkamp TR, Fleming MD, Camargo FD. Regulation of progenitor cell proliferation and granulocyte function by microRNA-223. Nature
2008; 451 (7182): 1125–9.
Vanpoucke G, Goossens S, De Craene B, Gilbert B, van Roy F, Berx G. GATA-4 and MEF2C transcription factors control the tissue-specific expression of the alphaT-catenin gene CTNNA3. Nucleic Acids Res
2004; 32 (14): 4155–65.
Zhou W, Fong MY, Min Y, Somlo G, Liu L, Palomares MR, Yu Y, Chow A, O'Connor ST, Chin AR, Yen Y, Wang Y, Marcusson EG, Chu P, Wu J, Wu X, Li AX, Li Z, Gao H, Ren X, Boldin MP, Lin PC, Wang SE. Cancer-secreted miR-105 destroys vascular endothelial barriers to promote metastasis. Cancer Cell
2014; 25 (4): 501–15.
Fong MY, Zhou W, Liu L, Alontaga AY, Chandra M, Ashby J, Chow A, O'Connor ST, Li S, Chin AR, Somlo G, Palomares M, Li Z, Tremblay JR, Tsuyada A, Sun G, Reid MA, Wu X, Swiderski P, Ren X, Shi Y, Kong M, Zhong W, Chen Y, Wang SE. Breast-cancer-secreted miR-122 reprograms glucose metabolism in premetastatic niche to promote metastasis. Nat Cell Biol
2015; 17 (2): 183–94.
Ramirez M, Rajaram S, Steininger RJ, Osipchuk D, Roth MA, Morinishi LS, Evans L, Ji W, Hsu CH, Thurley K, Wei S, Zhou A, Koduru PR, Posner BA, Wu LF, Altschuler SJ. Diverse drug-resistance mechanisms can emerge from drug-tolerant cancer persister cells. Nat Commun
2016; 7: 10690.
Gonzalez-Angulo AM, Morales-Vasquez F, Hortobagyi GN. Overview of resistance to systemic therapy in patients with breast cancer. Adv Exp Med Biol
2007; 608: 1–22.
Kutanzi KR, Yurchenko OV, Beland FA, Checkhun VF, Pogribny IP. MicroRNA-mediated drug resistance in breast cancer. Clin Epigenetics
2011; 2 (2): 171–85.
Chen WX, Cai YQ, Lv MM, Chen L, Zhong SL, Ma TF, Zhao JH, Tang JH. Exosomes from docetaxel-resistant breast cancer cells alter chemosensitivity by delivering microRNAs. Tumour Biol
2014; 35 (10): 9649–59.
Thomas SN, Liao Z, Clark D, Chen Y, Samadani R, Mao L, Ann DK, Baulch JE, Shapiro P, Yang AJ. Exosomal proteome profiling: A potential multi-marker cellular phenotyping tool to characterize hypoxia-induced radiation resistance in breast cancer. Proteomes
2013; 1 (2): 87–108.
Jung KO, Youn H, Lee CH, Kang KW, Chung JK. Visualization of exosome-mediated miR-210 transfer from hypoxic tumor cells. Oncotarget
2017; 8 (6): 9899–910.
Yu DD, Wu Y, Zhang XH, Lv MM, Chen WX, Chen X, Yang SJ, Shen H, Zhong SL, Tang JH, Zhao JH. Exosomes from adriamycin-resistant breast cancer cells transmit drug resistance partly by delivering miR-222. Tumour Biol
2016; 37 (3): 3227–35.
Wei Y, Lai X, Yu S, Chen S, Ma Y, Zhang Y, Li H, Zhu X, Yao L, Zhang J. Exosomal miR-221/222 enhances tamoxifen resistance in recipient ER-positive breast cancer cells. Breast Cancer Res Treat
2014; 147 (2): 423–31.
Zhong S, Chen X, Wang D, Zhang X, Shen H, Yang S, Lv M, Tang J, Zhao J. MicroRNA expression profiles of drug-resistance breast cancer cells and their exosomes. Oncotarget
2016; 7 (15): 19601–9.
Wang S, Li W, Xue Z, Lu Y, Narsinh K, Fan W, Li X, Bu Q, Wang F, Liang J, Wu K, Cao F. Molecular imaging of p53 signal pathway in lung cancer cell cycle arrest induced by cisplatin. Mol Carcinog
2013; 52 (11): 900–7.
Wu Y, Ginther C, Kim J, Mosher N, Chung S, Slamon D, Vadgama JV. Expression of Wnt3 activates Wnt/beta-catenin pathway and promotes EMT-like phenotype in trastuzumab-resistant HER2-overexpressing breast cancer cells. Mol Cancer Res
2012; 10 (12): 1597–606.
Javidi-Sharifi N, Traer E, Martinez J, Gupta A, Taguchi T, Dunlap J, Heinrich MC, Corless CL, Rubin BP, Druker BJ, Tyner JW. Crosstalk between KIT and FGFR3 promotes gastrointestinal stromal tumor cell growth and drug resistance. Cancer Res
2015; 75 (5): 880–91.
Block M, Grundker C, Fister S, Kubin J, Wilkens L, Mueller MD, Hemmerlein B, Emons G, Gunthert AR. Inhibition of the AKT/mTOR and erbB pathways by gefitinib, perifosine and analogs of gonadotropin-releasing hormone I and II to overcome tamoxifen resistance in breast cancer cells. Int J Oncol
2012; 41 (5): 1845–54.
Blagodatski A, Poteryaev D, Katanaev VL. Targeting the Wnt pathways for therapies. Mol Cell Ther
2014; 2: 28.
Chakrabarty A, Bhola NE, Sutton C, Ghosh R, Kuba MG, Dave B, Chang JC, Arteaga CL. Trastuzumab-resistant cells rely on a HER2-PI3K-FoxO-survivin axis and are sensitive to PI3K inhibitors. Cancer Res
2013; 73 (3): 1190–200.
Pigati L, Yaddanapudi SC, Iyengar R, Kim DJ, Hearn SA, Danforth D, Hastings ML, Duelli DM. Selective release of microRNA species from normal and malignant mammary epithelial cells. PLoS One
2010; 5 (10): e13515.
Eichelser C, Stuckrath I, Muller V, Milde-Langosch K, Wikman H, Pantel K, Schwarzenbach H. Increased serum levels of circulating exosomal microRNA-373 in receptor-negative breast cancer patients. Oncotarget
2014; 5 (20): 9650–63.
Hannafon BN, Trigoso YD, Calloway CL, Zhao YD, Lum DH, Welm AL, Zhao ZJ, Blick KE, Dooley WC, Ding WQ. Plasma exosome microRNAs are indicative of breast cancer. Breast Cancer Res
2016; 18 (1): 90.
Onitilo AA, Engel JM, Greenlee RT, Mukesh BN. Breast cancer subtypes based on ER/PR and Her2 expression: Comparison of clinicopathologic features and survival. Clin Med Res
2009; 7 (1-2): 4–13.
Blenkiron C, Goldstein LD, Thorne NP, Spiteri I, Chin SF, Dunning MJ, Barbosa-Morais NL, Teschendorff AE, Green AR, Ellis IO, Tavaré S, Caldas C, Miska EA. MicroRNA expression profiling of human breast cancer identifies new markers of tumor subtype. Genome Biol
2007; 8 (10): R214.
Joyce DP, Kerin MJ, Dwyer RM. Exosome-encapsulated microRNAs as circulating biomarkers for breast cancer. Int J Cancer
2016; 139 (7): 1443–8.
Lee JK, Park SR, Jung BK, Jeon YK, Lee YS, Kim MK, Kim YG, Jang JY, Kim CW. Exosomes derived from mesenchymal stem cells suppress angiogenesis by down-regulating VEGF expression in breast cancer cells. PLoS One
2013; 8 (12): e84256.
Jang JY, Lee JK, Jeon YK, Kim CW. Exosome derived from epigallocatechin gallate treated breast cancer cells suppresses tumor growth by inhibiting tumor-associated macrophage infiltration and M2 polarization. BMC Cancer
2013; 13: 421.
Wang KC, Garmire LX, Young A, Nguyen P, Trinh A, Subramaniam S, Wang N, Shyy JY, Li YS, Chien S. Role of microRNA-23b in flow- regulation of Rb phosphorylation and endothelial cell growth. Proc Natl Acad Sci U S A
2010; 107 (7): 3234-9.
Wu YY, Chen YL, Jao YC, Hsieh IS, Chang KC, Hong TM. miR-320 regulates tumor angiogenesis driven by vascular endothelial cells in oral cancer by silencing neuropilin 1. Angiogenesis
2014; 17 (1): 247–60.
Hannafon BN, Carpenter KJ, Berry WL, Janknecht R, Dooley WC, Ding WQ. Exosome-mediated microRNA signaling from breast cancer cells is altered by the anti-angiogenesis agent docosahexaenoic acid (DHA). Mol Cancer
2015; 14: 133.
Bovy N, Blomme B, Frères P, Dederen S, Nivelles O, Lion M, Carnet O, Martial JA, Noël A, Thiry M, Jérusalem G, Josse C, Bours V, Tabruyn SP, Struman I. Endothelial exosomes contribute to the antitumor response during breast cancer neoadjuvant chemotherapy via microRNA transfer. Oncotarget
2015; 6 (12): 10253–66.
O'Brien K, Lowry MC, Corcoran C, Martinez VG, Daly M, Rani S, Gallagher WM, Radomski MW, MacLeod RA, O'Driscoll L. miR-134 in extracellular vesicles reduces triple-negative breast cancer aggression and increases drug sensitivity. Oncotarget
2015; 6 (32): 32774–89.
van den Boorn JG, Schlee M, Coch C, Hartmann G. SiRNA delivery with exosome nanoparticles. Nat Biotechnol
2011; 29 (4): 325–6.
Thind A, Wilson C. Exosomal miRNAs as cancer biomarkers and therapeutic targets. J Extracell Vesicles
2016; 5: 31292.
Heneghan HM, Miller N, Lowery AJ, Sweeney KJ, Kerin MJ. microRNAs as novel biomarkers for breast cancer. J Oncol
2009; 2009: 950201.
Sachdeva M, Wu H, Ru P, Hwang L, Trieu V, Mo YY. microRNA-101-mediated Akt activation and estrogen-independent growth. Oncogene
2011; 30 (7): 822–31.
Carnero A, Blanco-Aparicio C, Renner O, Link W, Leal JF. The PTEN/PI3K/AKT signalling pathway in cancer, therapeutic implications. Curr Cancer Drug Targets
2008; 8 (3): 187–98.
Munagala R, Aqil F, Gupta RC. Exosomal miRNAs as biomarkers of recurrent lung cancer. Tumour Biol
2016; 37 (8): 10703–14.
Pfeffer SR, Grossmann KF, Cassidy PB, Yang CH, Fan M, Kopelovich L, Leachman SA, Pfeffer LM. Detection of exosomal miRNAs in the plasma of melanoma patients. J Clin Med
2015; 4 (12): 2012–27.
Rupp AK, Rupp C, Keller S, Brase JC, Ehehalt R, Fogel M, Moldenhauer G, Marme F, Sultmann H, Altevogt P. Loss of EpCAM expression in breast cancer derived serum exosomes: role of proteolytic cleavage. Gynecol Oncol
2011; 122 (2): 437–46.