Role of Exosome on Certain Types of Cancers

Introduction

Exosomes are Nano vesicles that can play a role in contact between cells by serving as carriers of Functional contents such as donor-to-recipient proteins, lipids, RNA molecules, and circulating DNA Cellular cells.¹ The exosomes exist as extracellular vesicles (EVs). In comparison to microvesicles (MVs; 100-1000 nm) and apoptotic entities (50–500 nm), Exosomes are membraned endocytic vesicles ranging in size from 30 to 100 nm.² Exosome cargo includes primarily DNA, proteins, lipids, mRNA, and miRNA. Mechanistically liberated exosome provides intercellular contact from the cell of origin either through direct cellular uptake or through target internalization recipient cell receptor.³ Their secretions to the compartments of extracellular media and body fluids broncho alveolar lavage, a variety of cells (mesenchymal cells, synovial fluid, bile, serum, milk, and urine) were reported; fibroblasts, epithelial cells, platelets, cells expressing antigens and tumor cells.⁴ Exosomes are filled with numerous molecules, including nucleic acids, cytokines, and bioactive Compounds, enzymes, and surface-encoded proteins that are present as exosome receptors act on by either inducing signaling pathways or altering their cellular phenotypes pass of new genetic substances and receptors.⁵ Whether specific cellular constituents are shuttled through an organized mechanism into exosomes, or whether it remains unknown that exosome packaging is only a random process. The content and number of exosomes likely changed depending on whether the cells undergo different stressors or it can contain stimuli and exosomes made from the same cell’s different constituents.⁶ Allied exosomes are produced when endosomal recycling is triggered Pathway involving endosomal and multi-secular (MVB) formation and secretion with the aid of Rab GTPase.⁷ Due to their inclusion in most body fluids and their stability exosomes have great potential as liquid biopsy specimens and similarity of their contents to parental cells.⁸

Function of Exosomes

The exact function of the exosomes is still unclear. Beginning hypotheses support the notion that exosomes can be used as cellular garbage bags expelling waste and/or non-functional cells elections. Besides, exosomes are endocytic extracellular vesicles and are possibly produced for the recycling of cell surface proteins and in turn, modulate external signaling.⁹ Whilst this means that the exosomes contain particular constituents present in excess was not specifically observed or proved in a given cell. Whether unique cellular constituents are shuttled through an ordered process into exosomes, or whether it remains unknown that exosome packaging is only a random operation. The content and number of exosomes changed.¹⁰ 

Functions of Exosomes In Cancer

Cancer is a big global public health concern. Early diagnosis of cancer and general knowledge of cancer risk factors increased survival. Nonetheless, there is an urgent need for greater productivity and less intrusive surrogate markers that could provide early guidance diagnosis, preference of the clinical treatment methods patients, and reliable prognostic predictions. In cancer, exosomes were identified in large part as promoters of the progression of tumors.¹¹ Exosomes play a very significant role in the development of cancer, metastasis and therapeutic effectiveness of special interest is the role of exosomes in the production of cancer for oncologists because cancer cells are at least 10 times more elusive. Exosomes contain more exosomes than normal cells initiation, growth, progression, and drug-resistance tumors involving microenvironmental interactions by transferring nucleic and oncogenic proteins.⁹ It is conceivable, however, that exosomes often exhibit antitumor functions and services to curb disease change.^9,12 Further studies are needed to explore the possible beneficial aspects of exosomes in tumors exosomes instability and functional heterogeneity. Exosome functions in the pathological remodeling of organs other than cancer or during pregnancy are unraveled.¹³

The Benefits of Exosomes Therapy¹⁴

1) Help to treat pain and mobility problem

2) Help with arthritis and joint inflammation:

3) Exosome therapy can improve your libido

4) Exosome can help with hair loss or dry hair 

Challenges in Bringing of Exosomes Based Therapeutics

Researchers are now tasked with developing a healthy, feasible, and reproducible mesenchymal stem cell-exosome therapy with such promising preclinical findings in multiple disease models. However, major obstacles are being faced to take exosome-based therapies into clinical trials and evaluate the real potential of exosome-based therapies. The 'bad' methodologies are undoubtedly the big hurdles for exosome isolation and classification, and lack of standardization in the purification of exosomes. Similarto mesenchymal stem cell-therapy, difficulties in developing accurate measurements of exosome potency, and industrial scale-up problems would hinder a smooth transition to clinical development and need to be overcome at an early stage. Here we focus on the potential for therapeutic application of MSC-exosomes, outline related issues to promote their products, and provide guidance on the current challenges of clinical implementation of exosome-based therapies.^14,15

Applications of Exosomes

Exosomes have immense diagnostic and therapeutic potential, due to their wide range of functions. By controlling physiological functions, such as angiogenesis, contact between cells, coagulation, Exosomes are immune response and cell survival to the scientific fraternity globally. Their cellular secretions into body fluids (plasma, urine, cerebrospinal fluid (CSF), saliva. Exosomes are mini-copies of the cells theyoriginate from originally.¹⁶ As to their antigenicity (cancer and immune cells) and their potential for therapy (Primed-cells of the system and antigen); therefore, exosomes are considered of immense importance for the diagnostic and therapeutic uses.¹⁷

Exosomes In Diagnosis

Diagnostic Exosomes with specific signatures of proteins (Alix, TSG101, CD9, CD63, HSP70, and HSP90), RNA (mRNA) and (miRNA), and the usual lipid content of exosomes in body fluids (blood, serum, milk,Urine) is used as diagnostic markers for the early detection of different diseases.¹⁸ Exosomes RNAs from saliva, amniotic fluid, and urine were investigated concerning their use as a CD24 polymorphism diagnostic marker (CT; alanine to valine alteration) associated with modulation of Multiple Sclerosis (MS) progression, chronic hepatitis B, systemic lupus erythematosus (SLE), and arthritis in giant cells.¹⁹ Increases in the content of miRNA released into body fluids as part of exosomes provide insight into the growth of the disease.²⁰

Another essential source of exosomes in human saliva, which contains nucleic acids and Proteins, and diagnostic signatures for various diseases.^21,22 MiRNA levels in saliva Samples of the parotid and submandibular/sublingual regions collected from healthy controls and patients with Sjogren's syndrome have shown that miRNAs expressed strongly in parotid glands were presented differently. Michael et al. (2010) recorded a marked difference between the highly qualified six MiRNAs presented in Sjogren syndrome and healthy controls (Sjogren syndrome).²³

Exosomes in Therapeutics

The properties of exosomes, which include bioavailability, distribution, and stability under in vivoand in vitro conditions, and their abilities to cross the blood-brain barrier (BBB) and regulate geneexpression via the transfer of miRNA and small interfering RNA (siRNA) to target cells means they arepreferred over other extracellular vesicles as potential therapeutics.^9,12 Mesenchymal stem cells (MSCs) are stromal cells whose therapeutic potential is well established. These cells are located in bone marrow, cord umbilical, and adipose tissue.²⁴ 

General Role of Exosomes in Cancer Role of exosome proteins in cancer diagnosis:

The exosome is rich in proteins. It also contains cell-derived proteins, in addition to self-proteins. Exosomal proteins from cancer cells are becoming new biomarkers for the monitoring and assessment of cancer effectiveness based on the following characteristics: 1) Cancer-related lipids, proteins, RNA, and DNA in exosomes may be used for cancer testing.

The Figure 1 explains the role of the exosomes in preserving networks of cancer resistance. Exosome-mediated biological exports may induce a microenvironment good for resistance. Exosome released factor may promote a morphology of a) EMT cells resulting in stemming; b) promotes fibroblast-like cell formation that causes the desmoplastic (stromal) reaction. c) Promote processes of immune escape, and d) enable angiogenesis and metastasis. The mirrors expelled from exosomes can control multiple signaling pathways that cumulatively promote most tumor resistant phenotypes.

Breast cancer

In breast cancer, exosomal proteins are used as biomarkers in cells, cells with melanoma, and cells with multiple myeloma. Melo and et al.¹⁰ The miRNA biogenesis in exosomes revealed that the expression of their respective mRNA targets was inhibited, such as the homologous phosphatase and tensin (PTEN) and homeobox D10 (HOXD10) transcription factor, suggestinga contribution to a progression of breast cancer. Perseverant the rise in CEA and 15–3 levels of cancer antigen in breast cancer exosomes is closely linked to the number of cancer foci.²⁵

Figure 2 explains that Exosomes are released into the extracellular milieu and tumor microenvironment from breast cancer and stromal/cancer-associated fibroblast cells. Exosomes have been shown to play roles in invasion and metastasis of cancer cells, activation of stem cells, apoptosis, immune system cell interaction, and resistance to drugs.²⁶ Fibroblast-derived exosomes have been shown to play a role in growing metastasis and motility of breast cancer via the Wnt Pathway.²⁷

The signaling pathway for Wnt plays a role in cell migration, cell adhesion, stem cell maintenance, tissue patterning, and carcinogenesis, as reviewed by Zardawi et al. CD81 + exosomes from mouse fibroblast L cells were found to be present in the conditioned medium. Inhibition of breast cancer cell motility (MDA-MB-231) was observed following siRNA (small interfering RNA) knockdown of CD81 in L cells, thus indicating that CD81 controls the fibroblastic induction of breast cancer cell motility. MDA-MB-231 cell metastasis was substantially suppressed following the co-injection of an orthotopic breast cancer mouse model with MDA-MB-231 cells and CD81 knockdown L cells. L-cell – secreted CD81-positive exosomes have been found to control the motility of the breast cancer cells. The mechanism of action was found to rely on autocrine signaling of the Want – planar cell polarity.²⁸

In the treatment of breast cancer, drug resistance is a significant challenge, and exosomes / EVs are of particular interest in drug resistance studies. It wasexosomes with breast cancer cells found that stromal cells initiate cross-talk via Exosomes were found to be transmitted from stromal cells to breast cancer cells, thereby activating the signaling of antiviral RIG-I (retinoic acid-inducible gene 1 enzyme) and simultaneously activating NOTCH3 pathways to control the expansion of tumor-initiating cells resistant to therapy.²⁹ Research that uses exosomes in blood for the identification, development, and relapse of Bronchial cancer.^29,30 Exosomal transport of P-glycoprotein (P-gp) has been identified as a possible mechanism of drug resistance mediated by exosomes. Our research community initially demonstrated this about prostate cancer.³¹ More recently, it has been shown that exosomes from MCF-7 docetaxel-resistant cells pass drug resistance to MCF-7 docetaxel-sensitive cells. The proposed resistance mechanism is through the exosomal transmission of P-gp since exosomes derived from drug-resistant cells have higher P-gp concentrations than drug-sensitive cells.³²

Lung cancer

One of the most common cancers in both men and women is lung cancer. A major problem in lung cancer diagnosis is the lack of a common biomarker(s) for early diagnosis. At the time of diagnosis, about 70 percent of patients with lung cancer have locally advanced or metastatic disease. Recent studies indicate new methods may be useful for exosomes.³³ Platelet-secreted exosomes have been shown to support cancer growth and the metastasis of lung cancer cells.^34,35 Exosomes are involved in many cellular functions and intrinsic cancer pathways where they are potentially useful biomarkers.³⁶ Diverse protein components have been found to accumulate in exosomes secreted by cancer cells in the lung that may promote lung cancer and promote the production of diagnosis early stage. Jakobsen and others.³⁷ It reported CD317 receptor with epidermal growth factor (EGFR) expressed strongly on the exosomal surface, by examination extracellular vesicles secreted by cancer cells in the lungs. These molecules are active diagnostic biomarkers of cancer in the non-small cell lung (NSCLC). Li and al.^38,39 Exosomes recently in 30 Unique peripheral blood was reported to contain biomarkers, that is, exosomes and their associated components provide a theoretical basis for exploring molecular biomarkers for early-stage diagnosis of lung cancer.

Gastric cancer

Gastric cancer (GC) is widespread in many countries around the world as one of the most deadly cancers Nation. GC is the fourth most common cancer and the world's second leading cause of death from cancer.^40,41

As utility carriers, exosomes play a significant role in the activity of the cancer cells, the endothelial vascular cells, and those macrophages. Exosomes arising from GC cells the activation of the NF-B pathway could also be stimulated for the promotion of cancer progression in macrophages.⁴² Giles et al. suggested GC cells could cause differentiation of human umbilical mesenchymal stem cells to carcinoma-associated fibroblasts through the exosome-mediated transfer of TGF-ß and activation of the TGF-ß / Smad pathway, which may represent a new mechanism for MSC-to-CAF cancer transfer.⁴² Li and colleagues have found that exosomes from gastric cancer cells have greatly increased the proliferation and invasion of gastric cancer cells. Further analysis revealed that CD97 was involved in the promotion of GC cell proliferation and invasion by exosomes through activation of the MAPK signaling pathway.⁴³

Tumor cell functions are derived from exosomes in GC. Exosomes are increasingly involved in the progression of GC through the movement of functional biomolecules including tumorigenesis, metastasis, angiogenesis, immune evasion, and drug resistance. GC cells derived from exosomes can modulate immunity by activating neutrophil and macrophage pro-tumor phenotypes and inducing T cell differentiation into Th17 and Treg cells. Exosomes derived from GC cells can transform pericytes, fibroblasts, and MSCs to myofibroblasts to promote angiogenesis and metastasis in tumors. Also, GC cells derived from exosomes can cause endothelial cells to help the angiogenesis of tumors and promote substantial adhesion between mesothelial and GC cells. By acting on the liver stromal cells, GC cells derived exosomes may help to establish a favorable microenvironment for liver metastasis. Further, pre-adipocytes tend to differentiate exosomes derived from GC cells into brown-like forms.⁴⁴ Another essential feature of exosomes derived from GC is their ability to modulate immunity to tumors.  

A previous study by Qu et al. in 2009 showed that Jurkat T cell apoptosis was induced by gastric cancer exosomes in a time- and dose-dependent manner, regulated by the Cbl family of ubiquitin ligases by inactivating PI3K / Akt signals and mediating caspase activation. ⁴⁵More recently, Wang et al. reported that exosomes derived from gastric cancer cells can effectively induce the production of PD-1+ tumor-associated macrophages (TAMs), which interact directly with PD-L1+ cells to produce IL-10, resulting in dysfunction of CD8+ T cell and favorable conditions for GC progression.^46,47 The new ExoCarta version reveals that from 286 independent reports, there are 41,860 protein entries, 4946 mRNA entries, and 1116 lipid entries in exosomes. These exosomal cargoes may help explain their biogenesis process, classify their originating cells, and mediate their biological functions. Besides, Fu and colleagues discovered that TRIM3 protein levels in GC serum exosomes were significantly lower than those in healthy controls.⁴⁸ Exosomes are also at an early stage of use in GC therapy. GC immunotherapy was first used to treat exosomes in 2011. Zhong et al. showed that exosomes from malignant GC ascites have been able to promote dendritic cell maturation and induce a tumor-specific cytotoxic T lymphocyte response.⁴⁹

Pancreatic cancer

Abbreviations: cancer-related fibroblasts, CAFs; bone marrow mesenchymal stem cell, BMSC; a disinterring and a metalloproteinase-9, ADAM9; tumor-associated stroma, TAS; apoptotic peptidase activating factor 1, APAF1; deoxycytidine kinase, dCK; superoxide dismutase 2, SOD2; ephrin type-A receptor 2, EphA24,⁵⁰

Exosomes are important for the development of pancreatic cancer and the formation of drug resistance. The current treatment strategy, therefore, lies mainly in inhibiting the development of cancer cell exosomes and in blocking receptor cells from taking up particular exosomes. However, there is a lack of clear understanding of the way exosomes are generated and secreted. Ostrowski et al. identified the primary Rab GTPase for RNAi (RNAi) screening exosome secretion while noting that Rab27a and Rab27b mainly controlled this process.⁵¹

Liver cancer and cholangiocarcinoma

Cancers of the primary liver like hepatocellular carcinoma (HCC) and is the world's second-largest cause of cancer-related death and the incidence is increasing. An estimated sum was given in 2013 30,640 new US-diagnosed liver cancers and 21,670 new.⁵² In liver pathophysiology, multiple contacts or cross-talking methods between the two same cell types or between different types of cells are an unavoidable process by exosomes or other mechanisms. Knowledge of how hepatic cells interact by exosomes and the roles of cell-type-specific exosomes from each cell group would also promote studies of liver disease. Here we review and discuss the current knowledge of how hepatic cells interact with other cells through exosomes and how exosomal cargoes affect many signals between multiple types of hepatic cells.^53,54

A simplified model of intercellular contact in the liver, regulated by the exosome.

(a) Healthy hepatocytes release sphingosine kinase 2(SK2) exosomes which promote liver regeneration in two-thirds of partial hepatectomy (PH) liver. Hepatitis C Virus (HCV)-infected hepatocytes secrete exosomes with HCV RNA to infect the hepatocytes that are not infected. In exosomes derived from HCV-infected hepatocytes, microRNA (miR)-19a induces the transdifferentiating of quiescent stellate cells (qHSCs) into activated HSCs (aHSCs). When the liver is injured, damaged hepatocytes release exosomes that contain unknown toll-like 3 (TLR3)-ligands or miR-192 receptors. The ligands cause HSC activation, and miR-192 promotes aHSC proliferation

b) Exosomes with miR-214 or miR-199a-5p formed by qHSCs inhibit HSC activation, while exosomes with connective tissue growth factor (CTGF) released from aHSC stimulate HSC activation;

c) Injured LSECs release sphingosine kinase 1 (SK1)-containing exosomes which induce HSC activation;

d) Damaged cholangiocytes secrete exosomes that contain long non-coded H19 (H19) RNA. H19 brings hepatocyte injuries.⁵⁵

Colorectal Cancer

Mutation of an adenomatous polyposis coli (APC) was found in early-stage colorectal cancer, transparent adenomatous family chromosome, and most intermittent colorectal polyposis tumors⁵⁵. Moreover, may contribute to its occurrence and evolution. Comparison of transfecting SW480 cells APC gene secreted by plasmid and exosomal proteome SW480 cells showed the protein 4 (DKK 4) aboutdickkopf was widely expressed in SW480 cells transfecting plasmid APC gene exosomes. In these cells, DKK 4 gene promoter methylation level was decreased, indicating that DKK 4 transcription and expression of colorectal epithelial cells may be up-regulated by down-regulating methylation of DKK 4 gene promoter, and further encouraging occurrence colorectal cancer development by exosomes, which secrete DKK 4 and induce mutation of the APC genes. Comparison of the exosomal proteome with wild type KRAS DKS-8 DLD-1 cells in human colon adenocarcinoma and K-RAS mutant type DKO-1 cells suggested that DKS8 is not only significantly secreted by DKO-1 exosomes proliferated but its potential for invasion also increased. These studies have shown that colorectal cancer is exosomes have been instrumental in the survival of cancer cells survival, Microenvironmental Proliferation and Invasion ^56,57Exosomes contain a portion of the tumor-derived cell genome, transcriptome, and secretome. Exosomes have been reported to carry Oncoproteins, proteins for tumor suppressors, transcriptional regulators, splicing factors, and RNAs (mRNAs, microRNAs, and other non-coding RNAs).58Besides, exosomes may contain DNA fragments that may provide information about the origin of cancer cells. ⁵⁹

Renal cell carcinoma 

Raimondo et al. examined Exosomes in urine samples with nine renal-cell carcinoma patients and 23 patients’ good controls and found metalloprotein ase 9 (MMP9) matrix, ceruloplasmin (Cp), podocalyxin (PC) matrix, large levels of DKK 4, and carbonic anhydrase IX (CAIX) Phrased. However, aquaporin-1 (AQP-1), extracellular matrix metalloproteinase inducer (EMMPRIN), neprilysin (CD10), dipeptidase 1, and syntenin-1 were repressed. Exosomal proteomics applied of 10 proteins potential therapeutic benefit of early-stage renal diagnosis a carcinoma of cells.⁶⁰

Prostate cancer

In patients with prostate cancer, Nilsson et al. found that urinary exosomes expressed β-catenin, prostate, etc. cancer gene-3 (PCA-3), serine protease transmembrane 2-ETS transcription factor gene linked to the family member fusion (TMPRSS2 -ERG) with other markers linked to prostate cancer. The expression of antigen-specific to the prostate (PSA) and antigen-specific to prostate membranes (PSMA) urinary exosomes of prostate cancer patients showing risk for prostate cancer were also identified Cancer patients' diagnosis and control. 4,61Exosomes derived from cells of the prostate cancer lead to the chemoresistance of cancer. The exosomes' lipid bilayer membrane makes them promising drug carriers and other therapeutic molecules that target prostate cancer. Also, exosomes can be identified and extracted for prostate cancer diagnosed from different body fluids.⁵¹

In Figure 5 prostate cancer cells modulate surrounding stromal cells. Affected stromal cells use the exosomes to modulate the microenvironment that can facilitate growth and metastasis of tumors. Exosomes derived from cancer cells in the prostate may contribute to cancer drug resistance. Exosomal lipid bilayer membrane makes them promising drug carriers and other therapeutic molecules target

Ovarian cancer

One of the deadliest types of cancer in ovaries until recently, women lacked clear biomarkers, and it is useful to detect. About 70 percent of ovarian cancer cases are diagnosed at an advanced stage, which only has a survival rate of 20 percent within 5 years of diagnosis. If, however, diagnosed early (stage I), survival rates are over 90%. Ovarian cancer cells detach themselves from the primary site during the process of peritoneal dissemination originally from (ovary and/or fallopian tube). These cancer cells subsequently spread through the peritoneal cavity and connect the omentum, which is the prevalent location, to the surface of peritoneal organs, particularly the omentum metastatic breast cancer.^62,63 Several studies have shown that exosomes derived from cancer cells reprogram or teach other cells to Support tumor survival and promoting metastasis. Therefore, exosomes that are secreted by cell microenvironments of tumors including fibroblasts, mesothelial cells, adipocytes, and immune cells cancer cells are also affected. Many studies have shown that this morphological transition is mediated by exosomes from cancer cells and tumor microenvironments.^10,64,65 Proteomic studies have shown that exosomes contain transforming beta growth factor (TGFβ), alpha tumor necrosis factor (TNFα), interleukin (IL)-6, β-catenin, and metalloproteinase matrix (MMP) and are involved in the EMT method. The exosome-derived mesenchymal stem cells (MSC) and macrophages promote breast cancer migrationand/or invasion through Wnt signaling activation.^66,67

Conclusions

Exosomes play an important role in different types of cancers. Exosome being Nanostructure in nature, it reaches tumor part due to its hypoxia areas, intact blood vessel barrier, and systematic circulation in the body. Most of the medicine during the clinical trial does not cross the blood-brain barrier but exosomes can cross blood-brain barriers, which is another important role of the exosome. Exosomes contain primarily DNA proteins, mRNA which transfers from one part to another which kills the cancer cells without touching the helper cells. Exosomes also involve in the pathogenesis of different diseasesand intercellular communication. At present, the application of exosomes in the diagnosis and treatment of cancer is still in the initial stage. Further research into exosomes, including biogenesis, secretion, interaction with target cells, and function of the exosomal component, will enhance medical care applications and increase the survival rate of a cancer patient in the future.

Acknowledgments

Authors acknowledge Dr. J. Thimmasetty, Professor, Bapuji Pharmacy College, Davangere for his help in writing this article.

Conflicts of Interest 

The authors declare no conflicts of interest.