Proteomic Analyses of Fibroblast- and Serum-Derived Exosomes Identify QSOX1 as a Marker for Non-invasive Detection of Colorectal Cancer

Extracellular vesicle biomarkers in circulation for colorectal cancer detection: a systematic review and meta-analysis

We provided an overview which evaluated the diagnostic performance of circulation EV biomarkers for CRC from PubMed, Medline, and Web of Science until 21 August 2022.Weidentified 48 studies that involved 7727 participants and evaluated 162 plasma/serum individual EV biomarkers including 117 RNAs and 45 proteins, as well as 45 EV biomarker panels for CRC detection. 12 studies evaluated the diagnostic performance of EV biomarkers for early CRC. The summarized sensitivity, specificity, and AUC value of individual EV RNAs and EV RNA panels were 76%, 75%, 0.87 and 82%, 79% and 0.90, respectively. Meanwhile, those of individual EV proteins and EV protein panels were 85%, 84%, 0.92 and 87%, 83%, 0.92, respectively. These results indicated that EV biomarker panels revealed superior diagnostic performance than the corresponding individual biomarkers. In early CRC, EV biomarkers showed available diagnostic value with the sensitivity, specificity, and AUC value of 80%, 75%, and 0.89.In subgroup analyses, EV miRNAs and LncRNAs held similar diagnostic value with the sensitivity, specificity and AUC value of 75%, 78%, 0.90 and 79%, 72%, 0.83, which was highly consistent with the whole EV RNAs. Significantly, the diagnostic values of EV miRNAs in plasma were marginally higher than those based on serum. In detail, the sensitivity, specificity, and AUC values were 79%, 81%, and 0.92 in plasma, as well as 74%, 77%, and 0.88 in serum, respectively. Therefore, circulation EV biomarkers could be considered as a promising biomarker for the early detection of CRC.

The multifaceted role of extracellular vesicles (EVs) in colorectal cancer: metastasis, immune suppression, therapy resistance, and autophagy crosstalk

Extracellular vesicles (EVs) are lipid bilayer structures released by all cells and widely distributed in all biological fluids. EVs are implicated in diverse physiopathological processes by orchestrating cell-cell communication. Colorectal cancer (CRC) is one of the most common cancers worldwide, with metastasis being the leading cause of mortality in CRC patients. EVs contribute significantly to the advancement and spread of CRC by transferring their cargo, which includes lipids, proteins, RNAs, and DNAs, to neighboring or distant cells. Besides, they can serve as non-invasive diagnostic and prognostic biomarkers for early detection of CRC or be harnessed as effective carriers for delivering therapeutic agents. Autophagy is an essential cellular process that serves to remove damaged proteins and organelles by lysosomal degradation to maintain cellular homeostasis. Autophagy and EV release are coordinately activated in tumor cells and share common factors and regulatory mechanisms. Although the significance of autophagy and EVs in cancer is well established, the exact mechanism of their interplay in tumor development is obscure. This review focuses on examining the specific functions of EVs in various aspects of CRC, including progression, metastasis, immune regulation, and therapy resistance. Further, we overview emerging discoveries relevant to autophagy and EVs crosstalk in CRC.

Prospects of liquid biopsy in the prognosis and clinical management of gastrointestinal cancers

Gastrointestinal (GI) cancers account for one-fourth of the global cancer incidence and are incriminated to cause one-third of cancer-related deaths. GI cancer includes esophageal, gastric, liver, pancreatic, and colorectal cancers, mostly diagnosed at advanced stages due to a lack of accurate markers for early stages. The invasiveness of diagnostic methods like colonoscopy for solid biopsy reduces patient compliance as it cannot be frequently used to screen patients. Therefore, minimally invasive approaches like liquid biopsy may be explored for screening and early identification of gastrointestinal cancers. Liquid biopsy involves the qualitative and quantitative determination of certain cancer-specific biomarkers in body fluids such as blood, serum, saliva, and urine to predict disease progression, therapeutic tolerance, toxicities, and recurrence by evaluating minimal residual disease and its correlation with other clinical features. In this review, we deliberate upon various tumor-specific cellular and molecular entities such as circulating tumor cells (CTCs), tumor-educated platelets (TEPs), circulating tumor DNA (ctDNA), cell-free DNA (cfDNA), exosomes, and exosome-derived biomolecules and cite recent advances pertaining to their use in predicting disease progression, therapy response, or risk of relapse. We also discuss the technical challenges associated with translating liquid biopsy into clinical settings for various clinical applications in gastrointestinal cancers.

Decreased NSD2 impairs stromal cell proliferation in human endometrium via reprogramming H3K36me2

In brief

The proliferation of the endometrium is regulated by histone methylation. This study shows that decreased NSD2 impairs proliferative-phase endometrial stromal cell proliferation in patients with recurrent implantation failure via epigenetic reprogramming of H3K36me2 methylation on the promoter region of MCM7.

Abstract

Recurrent implantation failure (RIF) is a formidable challenge in assisted reproductive technology because of its unclear molecular mechanism. Impaired human endometrial stromal cell (HESC) proliferation disrupts the rhythm of the menstrual cycle, resulting in devastating disorders between the embryo and the endometrium. The molecular function of histone methylation enzymes in modulating HESC proliferation remains largely uncharacterized. Herein, we found that the levels of histone methyltransferase nuclear receptor binding SET domain protein 2 (NSD2) and the dimethylation of lysine 36 on histone H3 are decreased significantly in the proliferative-phase endometrium of patients with RIF. Knockdown of NSD2 in an HESC cell line markedly impaired cell proliferation and globally reduced H3K36me2 binding to chromatin, leading to altered expression of many genes. Transcriptomic analyses revealed that cell cycle-related gene sets were downregulated in the endometrium of patients with RIF and in NSD2‑knockdown HESCs. Furthermore, RNA-sequencing and CUT&Tag sequencing analysis suggested that NSD2 knockdown reduced the binding of H3K36me2 to the promoter region of cell cycle marker gene MCM7 (encoding minichromosome maintenance complex component 7) and downregulated its expression. The interaction of H3K36me2 with the MCM7 promoter was verified using chromatin immunoprecipitation-quantitative real-time PCR. Our results demonstrated a unifying epigenome-scale mechanism by which decreased NSD2 impairs endometrial stromal cell proliferation in the proliferative-phase endometrium of patients with RIF.

The role of extracellular vesicles from placenta and endometrium in pregnancy: Insights from tumor biology

Extracellular vesicles (EVs) are small membrane-bound particles secreted by various cell types that play a critical role in intercellular communication by packaging and delivering biomolecules. In recent years, EVs have emerged as essential messengers in mediating physiological and pathological processes in tumor biology. The tumor microenvironment (TME) plays a pivotal role in tumor generation, progression, and metastasis. In this review, we provide an overview of the impact of tumor-derived EVs on both tumor cells and the TME. Moreover, we draw parallels between tumor biology and pregnancy, as successful embryo implantation also requires intricate intercellular communication between the placental trophecepiblast and the endometrial epithelium. Additionally, we discuss the involvement of EVs in targeting immune responses, trophoblast invasion, migration, and angiogenesis, which are shared biological processes between tumors and pregnancy. Specifically, we highlight the effects of placenta-derived EVs on the fetal-maternal interface, placenta, endometrium, and maternal system, as well as the role of endometrium-derived EVs in embryo-endometrial communication. However, challenges still exist in EVs research, including the standardization of EVs isolation methods for diagnostic testing, which also apply to reproductive systems where EVs-mediated communication is proposed to take place. Through this review, we aim to deepen the understanding of EVs, particularly in the context of reproductive biology, and encourage further investigation in this field.

Development of tandem antigen capture ELISAs measuring QSOX1 isoforms in plasma and serum

QSOX1 is a sulfhydryl oxidase that has been identified as a potential biomarker in multiple cancer types as well as acute decompensated heart failure. Three anti-QSOX1 monoclonal antibodies (mAbs) were generated: 2F1, 3A10, and 56-3. MAbs 2F1 and 3A10 were generated against the short isoform of recombinant QSOX1 (rQSOX1-S), and mAb 56-3 was generated against a peptide (NEQEQPLGQWHLS) from the long isoform of QSOX1 (QSOX1-L). Using these mAbs, tandem antigen capture ELISAs were developed to quantify both short and long isoforms of QSOX1 (Total QSOX1 ELISA) and QSOX1-L (QSOX1-L ELISA) in serum and plasma samples. The Total QSOX1 ELISA pairs mAbs 2F1 and 3A10 and has a limit of detection of 109.5 pM, while the QSOX1-L ELISA pairs mAbs 2F1 and 56-3 and has a limit of detection of 10 pM. The levels of total QSOX1 and QSOX1-L were measured in a cohort of paired sera and plasma from 61 donors ≥40 years old and 15 donors <40 years old. No difference in QSOX1 levels was detected between QSOX1-L and QSOX1-S in serum, but the mean concentration of QSOX1-L was found to be 3.21 nM in serum and 5.63 nM in plasma (**p = 0.006). Our tandem ELISAs demonstrate the wide range of concentrations of QSOX1-L and QSOX1-S among individual serum and plasma samples. Since the epitope of mAb 2F1 was mapped to the first CxxC motif at residues C70 and C73 and mAb 56-3 was generated against NEQEQPLGQWHLS in QSOX1-L, our findings support previous research which suggested that QSOX1-L is secreted from cells despite a putative transmembrane domain. The ELISAs reported here may be a useful tool for investigating QSOX1 isoforms as potential biomarkers in cancer and/or heart failure.

EDIL3 as an Angiogenic Target of Immune Exclusion Following Checkpoint Blockade

Immune checkpoint blockade (ICB) has become the standard of care for several solid tumors. Multiple combinatorial approaches have been studied to improve therapeutic efficacy. The combination of antiangiogenic agents and ICB has demonstrated efficacy in several cancers. To improve the mechanistic understanding of synergies with these treatment modalities, we performed screens of sera from long-term responding patients treated with ipilimumab and bevacizumab. We discovered a high-titer antibody response against EGF-like repeats and discoidin I-like domains protein 3 (EDIL3) that correlated with favorable clinical outcomes. EDIL3 is an extracellular protein, previously identified as a marker of poor prognosis in various malignancies. Our Tumor Immune Dysfunction and Exclusion analysis predicted that EDIL3 was associated with immune exclusion signatures for cytotoxic immune cell infiltration and nonresponse to ICB. Cancer-associated fibroblasts (CAF) were predicted as the source of EDIL3 in immune exclusion-related cells. Furthermore, The Cancer Genome Atlas Skin Cutaneous Melanoma (TCGA-SKCM) and CheckMate 064 data analyses correlated high levels of EDIL3 with increased pan-fibroblast TGFβ response, enrichment of angiogenic signatures, and induction of epithelial-to-mesenchymal transition. Our in vitro studies validated EDIL3 overexpression and TGFβ regulation in patient-derived CAFs. In pretreatment serum samples from patients, circulating levels of EDIL3 were associated with circulating levels of VEGF, and like VEGF, EDIL3 increased the angiogenic abilities of patient-derived tumor endothelial cells (TEC). Mechanistically, three-dimensional microfluidic cultures and two-dimensional transmigration assays with TEC endorsed EDIL3-mediated disruption of the lymphocyte function-associated antigen-1 (LFA-1)-ICAM-1 interaction as a possible means of T-cell exclusion. We propose EDIL3 as a potential target for improving the transendothelial migration of immune cells and efficacy of ICB therapy.

Circulating extracellular vesicle-derived MARCKSL1 is a potential diagnostic non-invasive biomarker in metastatic colorectal cancer patients

Extracellular vesicle-derived proteins are closely related to colorectal cancer metastasis, and early detection and diagnosis of colorectal cancer metastasis is very important to improve the prognosis. In this study, we evaluated the clinical significance of plasma EV-derived MARCKSL1 in differentiating patients with metastatic and nonmetastatic CRC. This study included 78 patients, including 40 patients with nonmetastatic colorectal cancer, 38 patients with metastatic colorectal cancer, and 15 healthy volunteers. The extracellular vesicles extracted from the participants' plasma were characterized through transmission electron microscopy, nanoparticle tracking analysis and western blotting. MARCKSL1 protein expression in the EVs was detected by ELISA, and the diagnostic efficacy of MARCKSL1 alone or in combination with CA125 and lymphocyte levels was evaluated by receiver operating characteristic curve (ROC) analysis. Pearson's correlation test was performed to detect the correlation between MARCKSL1, CA125, lymphocyte level and clinicopathological characteristics of tumors. The present study demonstrated that the level of circulating EV-derived MARCKSL1 in patients with metastatic colorectal cancer was significantly higher than that in patients with nonmetastatic colorectal cancer and healthy people. Combined with CA125 and lymphocyte levels, the best diagnostic effect was achieved, and the area under the ROC curve was 0.7480. Together, our findings indicated that circulating EV-derived MARCKSL1 could be used as a new potential diagnostic biomarker for metastatic CRC.

Cancer-associated fibroblasts and its derived exosomes: a new perspective for reshaping the tumor microenvironment

Cancer-associated fibroblasts (CAFs) are the most abundant stromal cells within the tumor microenvironment (TME). They extensively communicate with the other cells. Exosome-packed bioactive molecules derived from CAFs can reshape the TME by interacting with other cells and the extracellular matrix, which adds a new perspective for their clinical application in tumor targeted therapy. An in-depth understanding of the biological characteristics of CAF-derived exosomes (CDEs) is critical for depicting the detailed landscape of the TME and developing tailored therapeutic strategies for cancer treatment. In this review, we have summarized the functional roles of CAFs in the TME, particularly focusing on the extensive communication mediated by CDEs that contain biological molecules such as miRNAs, proteins, metabolites, and other components. In addition, we have also highlighted the prospects for diagnostic and therapeutic applications based on CDEs, which could guide the future development of exosome-targeted anti-tumor drugs.

The application of extracellular vesicles in colorectal cancer metastasis and drug resistance: recent advances and trends

Colorectal cancer (CRC) has high incidence and mortality rates and is one of the most common cancers of the digestive tract worldwide. Metastasis and drug resistance are the main causes of cancer treatment failure. Studies have recently suggested extracellular vesicles (EVs) as a novel mechanism for intercellular communication. They are vesicular particles, which are secreted and released into biological fluids, such as blood, urine, milk, etc., by a variety of cells and carry numerous biologically active molecules, including proteins, nucleic acids, lipids, metabolites, etc. EVs play a crucial part in the metastasis and drug resistance of CRC by delivering cargo to recipient cells and modulating their behavior. An in-depth exploration of EVs might facilitate a comprehensive understanding of the biological behavior of CRC metastasis and drug resistance, which might provide a basis for developing therapeutic strategies. Therefore, considering the specific biological properties of EVs, researchers have attempted to explore their potential as next-generation delivery systems. On the other hand, EVs have also been demonstrated as biomarkers for the prediction, diagnosis, and presumed prognosis of CRC. This review focuses on the role of EVs in regulating the metastasis and chemoresistance of CRC. Moreover, the clinical applications of EVs are also discussed.

Extracellular Vesicles in Colorectal Cancer: From Tumor Growth and Metastasis to Biomarkers and Nanomedications

Colorectal cancer (CRC) is a leading public health concern due to its incidence and high mortality rates, highlighting the requirement of an early diagnosis. Evaluation of circulating extracellular vesicles (EVs) might constitute a noninvasive and reliable approach for CRC detection and for patient follow-up because EVs display the molecular features of the cells they originate. EVs are released by almost all cell types and are mainly categorized as exosomes originating from exocytosis of intraluminal vesicles from multivesicular bodies, ectosomes resulting from outward budding of the plasma membrane and apoptotic bodies' ensuing cell shrinkage. These vesicles play a critical role in intercellular communications during physiological and pathological processes. They facilitate CRC progression and premetastatic niche formation, and they enable transfer of chemotherapy resistance to sensitive cells through the local or remote delivery of their lipid, nucleic acid and protein content. On another note, their stability in the bloodstream, their permeation in tissues and their sheltering of packaged material make engineered EVs suitable vectors for efficient delivery of tracers and therapeutic agents for tumor imaging or treatment. Here, we focus on the physiopathological role of EVs in CRCs, their value in the diagnosis and prognosis and ongoing investigations into therapeutic approaches.

Liquid biopsy approaches and immunotherapy in colorectal cancer for precision medicine: Are we there yet?

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths globally, with nearly half of patients detected in the advanced stages. This is due to the fact that symptoms associated with CRC often do not appear until the cancer has reached an advanced stage. This suggests that CRC is a cancer with a slow progression, making it curable and preventive if detected in its early stage. Therefore, there is an urgent clinical need to improve CRC early detection and personalize therapy for patients with this cancer. Recently, liquid biopsy as a non-invasive or nominally invasive approach has attracted considerable interest for its real-time disease monitoring capability through repeated sample analysis. Several studies in CRC have revealed the potential for liquid biopsy application in a real clinical setting using circulating RNA/miRNA, circulating tumor cells (CTCs), exosomes, etc. However, Liquid biopsy still remains a challenge since there are currently no promising results with high specificity and specificity that might be employed as optimal circulatory biomarkers. Therefore, in this review, we conferred the plausible role of less explored liquid biopsy components like mitochondrial DNA (mtDNA), organoid model of CTCs, and circulating cancer-associated fibroblasts (cCAFs); which may allow researchers to develop improved strategies to unravel unfulfilled clinical requirements in CRC patients. Moreover, we have also discussed immunotherapy approaches to improve the prognosis of MSI (Microsatellite Instability) CRC patients using neoantigens and immune cells in the tumor microenvironment (TME) as a liquid biopsy approach in detail.

IMP1/IGF2BP1 in human colorectal cancer extracellular vesicles

Colorectal cancer (CRC) is a leading cause of cancer-related death. There is an urgent need for new methods of early CRC detection and monitoring to improve patient outcomes. Extracellular vesicles (EVs) are secreted, lipid-bilayer bound, nanoparticles that carry biological cargo throughout the body and in turn exhibit cancer-related biomarker potential. RNA binding proteins (RBPs) are posttranscriptional regulators of gene expression that may provide a link between host cell gene expression and EV phenotypes. Insulin-like growth factor 2 RNA binding protein 1 (IGF2BP1/IMP1) is an RBP that is highly expressed in CRC with higher levels of expression correlating with poor prognosis. IMP1 binds and potently regulates tumor-associated transcripts that may impact CRC EV phenotypes. Our objective was to test whether IMP1 expression levels impact EV secretion and/or cargo. We used RNA sequencing, in vitro CRC cell lines, ex vivo colonoid models, and xenograft mice to test the hypothesis that IMP1 influences EV secretion and/or cargo in human CRC. Our data demonstrate that IMP1 modulates the RNA expression of transcripts associated with extracellular vesicle pathway regulation, but it has no effect on EV secretion levels in vitro or in vivo. Rather, IMP1 appears to affect EV regulation by directly entering EVs in a transformation-dependent manner. These findings suggest that IMP1 has the ability to shape EV cargo in human CRC, which could serve as a diagnostic/prognostic circulating tumor biomarker.NEW & NOTEWORTHY This work demonstrates that the RNA binding protein IGF2BP1/IMP1 alters the transcript profile of colorectal cancer cell (CRC) mRNAs from extracellular vesicle (EV) pathways. IMP1 does not alter EV production or secretion in vitro or in vivo, but rather enters CRC cells where it may further impact EV cargo. Our work shows that IMP1 has the ability to shape EV cargo in human CRC, which could serve as a diagnostic/prognostic circulating tumor biomarker.

Intercellular crosstalk between cancer cells and cancer-associated fibroblasts via extracellular vesicles

Intercellular communication plays an important role in cancer initiation and progression through direct contact and indirect interactions, such as via secretory molecules. Cancer-associated fibroblasts (CAFs) are one of the principal components of such communication with cancer cells, modulating cancer metastasis and tumour mechanics and influencing angiogenesis, the immune system, and therapeutic resistance. Over the past few years, there has been a significant increase in research on extracellular vesicles (EVs) as regulatory agents in intercellular communication. EVs enable the transfer of functional molecules, including proteins, mRNAs and microRNAs (miRNAs), to recipient cells. Cancer cells utilize EVs to dictate the specific characteristics of CAFs within the tumour microenvironment, thereby promoting cancer progression. In response to such "education" by cancer cells, CAFs contribute to cancer progression via EVs. In this review, we summarize experimental data indicating the pivotal roles of EVs in intercellular communication between cancer cells and CAFs.

Secretion of the disulfide bond generating catalyst QSOX1 from pancreatic tumor cells into the extracellular matrix: association with extracellular vesicles and matrix proteins

Quiescin sulfhydryl oxidase 1 (QSOX1) is a disulfide bond generating catalyst that is overexpressed in solid tumors. Expression of QSOX1 is linked to cancer cell invasion, tumor grade, and extracellular matrix (ECM) protein deposition. While the secreted version of QSOX1 is known to be present in various fluids and secretory tissues, its presence in the ECM of cancer is less understood. To characterize secreted QSOX1, we separated conditioned media based on size and density. We discovered that the majority of secreted QSOX1 resides in the EV-depleted fraction and in the soluble protein fraction. Very little QSOX1 could be detected in the EVP fraction. We used immunofluorescence to image subpopulations of EVs and found QSOX1 in Golgi-derived vesicles and medium/large vesicles, but in general, most extracellular QSOX1 was not attributed to these vesicles. Next, we quantified QSOX1 co-localization with the EV marker Alix. For the medium/large EVs, ~98% contained QSOX1 when fibronectin was used as a coating. However, on collagen coatings, only ~60% of these vesicles contained QSOX1, suggesting differences in EV cargo based on ECM coated surfaces. About 10% of small EVs co-localized with QSOX1 on every ECM protein surface except for collagen (0.64%). We next investigated adhesion of QSOX1 to ECM proteins in vitro and in situ and found that QSOX1 preferentially adheres to fibronectin, laminins, and Matrigel compared to gelatin and collagen. This mechanism was found to be, in part, mediated by the formation of mixed disulfides between QSOX1 and cysteine-rich ECM proteins. In summary, we found that QSOX1 (1) is in subpopulations of medium/large EVs, (2) seems to interact with small Alix+ EVs, and (3) adheres to cysteine-rich ECM proteins, potentially through the formation of intermediate disulfides. These observations offer significant insight into how enzymes, such as QSOX1, can facilitate matrix remodeling events in solid tumor progression.

Emerging role of exosomes in cancer progression and tumor microenvironment remodeling

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

Multi-Omics Integrative Approach of Extracellular Vesicles: A Future Challenging Milestone

In the era of multi-omic sciences, dogma on singular cause-effect in physio-pathological processes is overcome and system biology approaches have been providing new perspectives to see through. In this context, extracellular vesicles (EVs) are offering a new level of complexity, given their role in cellular communication and their activity as mediators of specific signals to target cells or tissues. Indeed, their heterogeneity in terms of content, function, origin and potentiality contribute to the cross-interaction of almost every molecular process occurring in a complex system. Such features make EVs proper biological systems being, therefore, optimal targets of omic sciences. Currently, most studies focus on dissecting EVs content in order to either characterize it or to explore its role in various pathogenic processes at transcriptomic, proteomic, metabolomic, lipidomic and genomic levels. Despite valuable results being provided by individual omic studies, the categorization of EVs biological data might represent a limit to be overcome. For this reason, a multi-omic integrative approach might contribute to explore EVs function, their tissue-specific origin and their potentiality. This review summarizes the state-of-the-art of EVs omic studies, addressing recent research on the integration of EVs multi-level biological data and challenging developments in EVs origin.

Liquid biopsy at the frontier of detection, prognosis and progression monitoring in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide and a leading cause of carcinogenic death. To date, surgical resection is regarded as the gold standard by the operator for clinical decisions. Because conventional tissue biopsy is invasive and only a small sample can sometimes be obtained, it is unable to represent the heterogeneity of tumor or dynamically monitor tumor progression. Therefore, there is an urgent need to find a new minimally invasive or noninvasive diagnostic strategy to detect CRC at an early stage and monitor CRC recurrence. Over the past years, a new diagnostic concept called “liquid biopsy” has gained much attention. Liquid biopsy is noninvasive, allowing repeated analysis and real-time monitoring of tumor recurrence, metastasis or therapeutic responses. With the advanced development of new molecular techniques in CRC, circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), exosomes, and tumor-educated platelet (TEP) detection have achieved interesting and inspiring results as the most prominent liquid biopsy markers. In this review, we focused on some clinical applications of CTCs, ctDNA, exosomes and TEPs and discuss promising future applications to solve unmet clinical needs in CRC patients.

Dynamic liquid biopsy components as predictive and prognostic biomarkers in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide. The diagnosis, prognosis and therapeutic monitoring of CRC depends largely on tissue biopsy. However, due to tumor heterogeneity and limitations such as invasiveness, high cost and limited applicability in longitudinal monitoring, liquid biopsy has gathered immense attention in CRC. Liquid biopsy has several advantages over tissue biopsy including ease of sampling, effective monitoring, and longitudinal assessment of treatment dynamics. Furthermore, the importance of liquid biopsy is signified by approval of several liquid biopsy assays by regulatory bodies indicating the powerful approach of liquid biopsy for comprehensive CRC screening, diagnostic and prognostics. Several liquid biopsy biomarkers such as novel components of the microbiome, non-coding RNAs, extracellular vesicles and circulating tumor DNA are extensively being researched for their role in CRC management. Majority of these components have shown promising results on their clinical application in CRC including early detection, observe tumor heterogeneity for treatment and response, prediction of metastases and relapse and detection of minimal residual disease. Therefore, in this review, we aim to provide updated information on various novel liquid biopsy markers such as a) oral microbiota related bacterial network b) gut microbiome-associated serum metabolites c) PIWI-interacting RNAs (piRNAs), microRNA(miRNAs), Long non-coding RNAs (lncRNAs), circular RNAs (circRNAs) and d) circulating tumor DNAs (ctDNA) and circulating tumor cells (CTC) for their role in disease diagnosis, prognosis, treatment monitoring and their applicability for personalized management of CRC.

The Role and Application of Exosomes in Gastric and Colorectal Cancer

Gastric cancer and colorectal cancer are malignant tumors found in the human gastrointestinal tract. Bidirectional communication between tumor cells and their microenvironment can be realized through the transmission of exosomes—small, cell-derived vesicles containing complex RNA and proteins. Exosomes play an important role in the proliferation, metastasis, immune response, and drug resistance of cancer cells. In this review, we focus on the role and application of exosomes in gastric and colorectal cancer. We also summarize the role of exosomes secreted by different types of cells in tumor development and as drug carriers in cancer treatment.

Characterization of Total RNA, CD44, FASN, and PTEN mRNAs from Extracellular Vesicles as Biomarkers in Gastric Cancer Patients

Simple Summary

Liquid biopsy is an easily accessible and non-invasive method to gain information about tumor diseases. The purpose of our study was to determine the value of extracellular vesicle-derived mRNAs as biomarkers for the diagnosis of gastric cancer and the response to its treatment. In a cohort of 87 gastric cancer patients and a control group of 14 individuals, we analyzed the absolute RNA concentration from extracellular vesicles (EV) and the relative levels of FASN, PTEN, and CD44 mRNA, and their correlation with clinico-pathological features. These correlated with treatment, tumor grading, and the pathological subtype according to Laurén’s classification. This might reflect their potential as both diagnostic and therapeutic predictors.

Abstract

In-depth characterization has introduced new molecular subtypes of gastric cancer (GC). To identify these, new approaches and techniques are required. Liquid biopsies are trendsetting and provide an easy and feasible method to identify and to monitor GC patients. In a prospective cohort of 87 GC patients, extracellular vesicles (EVs) were isolated from 250 µL of plasma. The total RNA was isolated with TRIZOL. The total RNA amount and the relative mRNA levels of CD44, PTEN, and FASN were measured by qRT-PCR. The isolation of EVs and their contained mRNA was possible in all 87 samples investigated. The relative mRNA levels of PTEN were higher in patients already treated by chemotherapy than in chemo-naïve patients. In patients who had undergone neoadjuvant chemotherapy followed by gastrectomy, a decrease in the total RNA amount was observed after neoadjuvant chemotherapy and gastrectomy, while FASN and CD44 mRNA levels decreased only after gastrectomy. The amount of RNA and the relative mRNA levels of FASN and CD44 in EVs were affected more significantly by chemotherapy and gastrectomy than by chemotherapy alone. Therefore, they are a potential biomarker for monitoring treatment response. Future analyses are needed to identify GC-specific key RNAs in EVs, which could be used for the diagnosis of gastric cancer patients in order to determine their molecular subtype and to accompany the therapeutic response.