Increasing circulating exosomes-carrying TRPC5 predicts chemoresistance in metastatic breast cancer patients

Investigating the Potential and Pitfalls of EV-Encapsulated MicroRNAs as Circulating Biomarkers of Breast Cancer

Extracellular vesicles (EVs) shuttle microRNA (miRNA) throughout the circulation and are believed to represent a fingerprint of the releasing cell. We isolated and characterized serum EVs of breast tumour-bearing animals, breast cancer (BC) patients, and healthy controls. EVs were characterized using transmission electron microscopy (TEM), protein quantification, western blotting, and nanoparticle tracking analysis (NTA). Absolute quantitative (AQ)-PCR was employed to analyse EV-miR-451a expression. Isolated EVs had the appropriate morphology and size. Patient sera contained significantly more EVs than did healthy controls. In tumour-bearing animals, a correlation between serum EV number and tumour burden was observed. There was no significant relationship between EV protein yield and EV quantity determined by NTA, highlighting the requirement for direct quantification. Using AQ-PCR to relate miRNA copy number to EV yield, a significant increase in miRNA-451a copies/EV was detected in BC patient sera, suggesting potential as a novel biomarker of breast cancer.

Calcium Signaling and the Regulation of Chemosensitivity in Cancer Cells: Role of the Transient Receptor Potential Channels

Cancer cells acquire the ability to modify the calcium signaling network by altering the expression and functions of cation channels, pumps or transporters. Calcium signaling pathways are involved in proliferation, angiogenesis, invasion, immune evasion, disruption of cell death pathways, ECM remodelling, epithelial-mesenchymal transition (EMT) and drug resistance. Among cation channels, a pivotal role is played by the Transient Receptor Potential non-selective cation-permeable receptors localized in plasma membrane, endoplasmic reticulum, mitochondria and lysosomes. Several findings indicate that the dysregulation in calcium signaling induced by TRP channels is responsible for cancer growth, metastasis and chemoresistance. Drug resistance represents a major limitation in the application of current therapeutic regimens and several efforts are spent to overcome it. Here we describe the ability of Transient Receptor Potential Channels to modify, by altering the intracellular calcium influx, the cancer cell sensitivity to chemotherapeutic drugs.

Exploring the key communicator role of exosomes in cancer microenvironment through proteomics

There have been many attempts to fully understand the mechanism of cancer behavior. Yet, how cancers develop and metastasize still remain elusive. Emerging concepts of cancer biology in recent years have focused on the communication of cancer with its microenvironment, since cancer cannot grow and live alone. Cancer needs to communicate with other cells for survival, and thus they secrete various messengers, including exosomes that contain many proteins, miRNAs, mRNAs, etc., for construction of the tumor microenvironment. Moreover, these intercellular communications between cancer and its microenvironment, including stromal cells or distant cells, can promote tumor growth, metastasis, and escape from immune surveillance. In this review, we summarized the role of proteins in the exosome as communicators between cancer and its microenvironment. Consequently, we present cancer specific exosome proteins and their unique roles in the interaction between cancer and its microenvironment. Clinically, these exosomes might provide useful biomarkers for cancer diagnosis and therapeutic tools for cancer treatment.

Extracellular vesicles as a novel source of biomarkers in liquid biopsies for monitoring cancer progression and drug resistance

Cancer-derived extracellular vesicles (EVs) have been detected in the bloodstream and other biofluids of cancer patients. They carry various tumor-derived molecules such as mutated DNA and RNA fragments, oncoproteins as well as miRNA and protein signatures associated with various phenotypes. The molecular cargo of EVs partially reflects the intracellular status of their cellular origin, however various sorting mechanisms lead to the enrichment or depletion of EVs in specific nucleic acids, proteins or lipids. It is becoming increasingly clear that cancer-derived EVs act in a paracrine and systemic manner to promote cancer progression by transferring aggressive phenotypic traits and drug-resistant phenotypes to other cancer cells, modulating the anti-tumor immune response, as well as contributing to remodeling the tumor microenvironment and formation of pre-metastatic niches. These findings have raised the idea that cancer-derived EVs may serve as analytes in liquid biopsies for real-time monitoring of tumor burden and drug resistance. In this review, we have summarized recent longitudinal clinical studies describing promising EV-associated biomarkers for cancer progression and tracking cancer evolution as well as pre-clinical and clinical evidence on the relevance of EVs for monitoring the emergence or progression of drug resistance. Furthermore, we outlined the state-of-the-art in the development and commercialization of EV-based biomarkers and discussed the scientific and technological challenges that need to be met in order to translate EV research into clinically applicable tools for precision medicine.

An Update on Novel Therapeutic Warfronts of Extracellular Vesicles (EVs) in Cancer Treatment: Where We Are Standing Right Now and Where to Go in the Future

Extracellular vesicles (EVs) are a heterogeneous group of membrane-bounded vesicles that are believed to be produced and secreted by presumably all cell types under physiological and pathological conditions, including tumors. EVs are very important vehicles in intercellular communications for both shorter and longer distances and are able to deliver a wide range of cargos including proteins, lipids, and various species of nucleic acids effectively. EVs have been emerging as a novel biotherapeutic platform to efficiently deliver therapeutic cargos to treat a broad range of diseases including cancer. This vast potential of drug delivery lies in their abilities to carry a variety of cargos and their ease in crossing the biological membranes. Similarly, their presence in a variety of body fluids makes them a potential biomarker for early diagnosis, prognostication, and surveillance of cancer. Here, we discuss the relatively least and understudied aspects of EV biology and tried to highlight the obstacles and limitations in their clinical applications and also described most of the new warfronts to beat cancer at multiple stages. However, much more challenges still remain to evaluate EV-based therapeutics, and we are very much hopeful that the current work prompts further discovery.

[Research advances on the role of exosomes in chemotherapy resistance of ovarian cancer]

Chemotherapy resistance is one of the biggest challenges in treatment of ovarian cancer. Mounting evidence shows that the exosomes shedding from tumor cells are considered to be involved in chemotherapy resistance of ovarian cancer by enhanced exosomal export of drugs, transferring RNAs or proteins and interfering with the bioactivity of therapeutic anti-tumor antibodies. In this review, we display the correlation between exosomes and chemotherapy resistance of ovarian cancer, the mechanism of exosomes involved in chemotherapy resistance of ovarian cancer, and discuss the potential clinical values of exosomes in chemotherapy resistance of ovarian cancer.

Ion Channels: New Actors Playing in Chemotherapeutic Resistance

In the battle against cancer cells, therapeutic modalities are drastically limited by intrinsic or acquired drug resistance. Resistance to therapy is not only common, but expected: if systemic agents used for cancer treatment are usually active at the beginning of therapy (i.e., 90% of primary breast cancers and 50% of metastases), about 30% of patients with early-stage breast cancer will have recurrent disease. Altered expression of ion channels is now considered as one of the hallmarks of cancer, and several ion channels have been linked to cancer cell resistance. While ion channels have been associated with cell death, apoptosis and even chemoresistance since the late 80s, the molecular mechanisms linking ion channel expression and/or function with chemotherapy have mostly emerged in the last ten years. In this review, we will highlight the relationships between ion channels and resistance to chemotherapy, with a special emphasis on the underlying molecular mechanisms.

Role of Extracellular Vesicles (EVs) in Cell Stress Response and Resistance to Cancer Therapy

Extracellular vesicles (EVs) are nanosized particles released by all cells that have been heralded as novel regulators of cell-to-cell communication. It is becoming increasingly clear that in response to a variety of stress conditions, cells employ EV-mediated intercellular communication to transmit a pro-survival message in the tumor microenvironment and beyond, supporting evasion of cell death and transmitting resistance to therapy. Understanding changes in EV cargo and secretion pattern during cell stress may uncover novel, targetable mechanisms underlying disease progression, metastasis and resistance to therapy. Further, the profile of EVs released into the circulation may provide a circulating biomarker predictive of response to therapy and indicative of microenvironmental conditions linked to disease progression, such as hypoxia. Continued progress in this exciting and rapidly expanding field of research will be dependent upon widespread adoption of transparent reporting standards and implementation of guidelines to establish a consensus on methods of EV isolation, characterisation and nomenclature employed.

Current Progresses of Exosomes as Cancer Diagnostic and Prognostic Biomarkers

Cancer related exosomes are nano-size membrane vesicles that play important roles in tumor microenvironment. Emerging evidence indicates that exosomes can load unique cargoes, including proteins and nucleic acids that reflect the condition of tumor. Therefore, exosomes are being used as diagnostic and prognostic biomarkers for various cancers. In this review, we describe the current progresses of cancer related exosomes, including their biogenesis, molecular contents, biological functions, sources where they are derived from, and methods for their detection. We will also discuss the current exosomal biomarkers and the utilization of them for early diagnosis and prognostics in cancer.

Calcium signaling and the therapeutic targeting of cancer cells

The calcium signal is implicated in a variety of processes important in tumor progression (e.g. proliferation and invasiveness). The calcium signal has also been shown to be important in other processes important in cancer progression including the development of resistance to current cancer therapies. In this review, we discuss how Ca²⁺ channels, pumps and exchangers may be drug targets in some cancer types. We consider what factors should be taken into account when considering an optimal Ca²⁺ channel, pump or exchanger as a candidate for further assessment as a novel drug target in cancer. We also present and summarize how some therapies for the treatment of cancer intersect with Ca²⁺ signaling and how pharmacological manipulation of the machinery of Ca²⁺ signaling could promote the effectiveness of some therapies. We also review new therapeutic opportunities for Ca²⁺ signal modulators in the context of the tumor microenvironment.

The Inner and Outer Qualities of Extracellular Vesicles for Translational Purposes in Breast Cancer

Breast cancer (BC) is the second most common cause of cancer mortality of women worldwide. BC is a systemic disease with a highly heterogeneous course of disease. Therefore, prognostic and diagnostic biomarkers are required to improve the clinical risk management. Cancer-derived or cancer-associated extracellular vesicles (EVs) procured from the bloodstream of BC patients offer a novel platform for the qualitative and quantitative screening and establishment of biomarkers. Here, we focus on common aspects of EVs, on the function of BC-derived EVs and their translational potential considering the EV abundancy, intravesicular as well as outer membrane-anchored composition and current challenges of implementation in clinical practice.

Effect of exosome biomarkers for diagnosis and prognosis of breast cancer patients

PURPOSE

Exosomes are gradually detected as an indicator for diagnosis and prognosis of breast cancer in clinic and a systematic review was conducted.

METHODS

A search for clinical studies published before July 1, 2017 was performed. Methods of exosome purification and identification from all studies were extracted. For diagnosis evaluation, the comparison of exosome biomarkers expression between breast cancer patients and healthy women was obtained; for prognosis prediction, the correlation between exosome biomarkers expression and chemotherapy resistance, overall survival (OS), disease-free survival (DFS), recurrence and metastasis of breast cancer was also extracted.

RESULTS

A total of 11 studies with 921 breast cancer patients were included. Ultracentrifugation is the most frequent method to purify exosomes and transmission electron microscopy is commonly used to identify exosomes. Exosome biomarkers (such as HER2, CD47, Del-1, miR-1246 and miR-21) in breast cancer patients are significantly higher than those in healthy controls, exosomal GSTP1 and TRPC5 are related to chemotherapy resistance, exosome-carrying TRPC5, NANOG, NEUROD1, HTR7, KISS1R and HOXC are correlated to PFS, DFS or OS, and some exosomal proteins (HER2, KDR, CD49d, CXCR4 and CD44) as well as miRNAs (miR-340-5p, miR-17-5p, miR-130a-3p, miR-93-5p) are associated with tumor recurrence or distant organ metastasis.

CONCLUSIONS

Exosome biomarkers can be used for early diagnosis and prognosis of breast cancer patients in clinic.

Elevated levels of extracellular vesicles are associated with therapy failure and disease progression in breast cancer patients undergoing neoadjuvant chemotherapy

Extracellular vesicles (EVs) have been discussed as a diagnostic tool for minimal residual disease (MRD) evaluation in breast cancer (BC) in addition to the analysis of circulating tumor cells (CTCs). Therefore, we investigated circulating EV levels as surrogate markers for disease monitoring and prediction of prognosis in primary, non-metastatic, locally advanced BC patients. EVs were enriched from blood samples of BC patients before and after neoadjuvant chemotherapy (NACT) and from healthy females. EV marker expression analysis was performed and EV sizes and concentrations were determined by nanoparticle tracking analysis. The results were associated with disease status, outcome and CTC presence, evaluated by gene expression analysis after enrichment. We demonstrated that i) the EV concentration was 40-fold higher in BC patients compared to healthy females, ii) the EV concentration increased during therapy, iii) an increased EV concentration pre-NACT was associated with therapy failure and iv) an elevated EV concentration post-NACT was associated with a reduced three-year progression-free and overall survival. Of note, residual stem cell-like and/or resistant CTCs after therapy were associated with a lower EV concentration post-NACT. Our study highlights that the concentration of EVs within BC blood samples may serve as a complementary parameter reflecting the status of MRD as well as therapy and disease outcome in parallel with CTC investigation.

Extracellular Vesicles Arising from Apoptotic Cells in Tumors: Roles in Cancer Pathogenesis and Potential Clinical Applications

It is known that apoptotic cells can have diverse effects on the tumor microenvironment. Emerging evidence indicates that, despite its renowned role in tumor suppression, apoptosis may also promote oncogenic evolution or posttherapeutic relapse through multiple mechanisms. These include immunomodulatory, anti-inflammatory, and trophic environmental responses to apoptosis, which drive tumor progression. Our group has introduced the term “onco-regenerative niche (ORN)” to describe a conceptual network of conserved cell death-driven tissue repair and regeneration mechanisms that are hijacked in cancer. We propose that, among the key elements of the ORN are extracellular vesicles (EVs), notably those derived from apoptotic tumor cells. EVs are membrane-delimited subcellular particles, which contain multiple classes of bioactive molecules including markers of the cell from which they are derived. EVs are implicated in an increasing number of physiological and pathological contexts as mediators of local and systemic intercellular communication and detection of specific EVs may be useful in monitoring disease progression. Here, we discuss the mechanisms by which EVs produced by apoptotic tumor cells—both constitutively and as a consequence of therapy—may mediate host responsiveness to cell death in cancer. We also consider how the monitoring of such EVs and their cargoes may in the future help to improve cancer diagnosis, staging, and therapeutic efficacy.

The molecular mechanisms of chemoresistance in cancers

Overcoming intrinsic and acquired drug resistance is a major challenge in treating cancer patients because chemoresistance causes recurrence, cancer dissemination and death. This review summarizes numerous molecular aspects of multi-resistance, including transporter pumps, oncogenes (EGFR, PI3K/Akt, Erk and NF-κB), tumor suppressor gene (p53), mitochondrial alteration, DNA repair, autophagy, epithelial-mesenchymal transition (EMT), cancer stemness, and exosome. The chemoresistance-related proteins are localized to extracellular ligand, membrane receptor, cytosolic signal messenger, and nuclear transcription factors for various events, including proliferation, apoptosis, EMT, autophagy and exosome. Their cross-talk frequently appears, such as the regulatory effects of EGFR-Akt-NF-κB signal pathway on the transcription of Bcl-2, Bcl-xL and survivin or EMT-related stemness. It is essential for the realization of the target, individualized and combine therapy to clarify these molecular mechanisms, explore the therapy target, screen chemosensitive population, and determine the efficacy of chemoreagents by cell culture and orthotopic model.

Exosomes: New players in cancer (Review)

The past decade has witnessed an exponential increase in research on exosomes. For many years considered to be extracellular debris, exosomes are now considered important mediators in intercellular communication. The capability of exosomes to transfer proteins, DNA, mRNA, as well as non-coding RNAs has made them an attractive focus of research into the pathogenesis of different diseases, including cancer. Increasing evidence suggests that tumor cells release a large sum of exosomes, which may not only influence proximal tumor cells and stromal cells in local microenvironment, but also can exert systemic effects when participating in blood circulation. In this study, we review the current understanding on this topic. The literature outlines two broad facets of exosomes in cancer: 1) promotion of tumor growth, tumorigenesis, tumor angiogenesis, tumor immune escape, drug resistance, and metastasis and 2) their role as promising biomarkers for cancer diagnosis and even as potential treatment targets for cancer patients.

Increasing circulating exosomes-carrying TRPC5 predicts chemoresistance in metastatic breast cancer patients

Chemoresistance, the major obstacle in breast cancer chemotherapy, results in unnecessary chemotherapy and wasting of medical resources. No feasible method has been available to predict chemoresistance before chemotherapy. In our previous study, elevated expression of transient receptor potential channel TRPC5 was found to be an essential element for chemoresistance in breast cancer cells, and it was determined that it could be transferred to chemosensitive breast cancer cells through releasing extracellular vesicles (EV) containing TRPC5 from chemoresistant cells, resulting in acquired chemoresistance. Exosomes, a type of EV, are secreted membrane-enclosed vesicles of 50-150-nm diameter. In this study we found that circulating exosomes in peripheral blood from breast cancer patients carried TRPC5. In the present study, circulating exosome-carrying TRPC5 (cirExo-TRPC5) level was significantly correlated with TRPC5 expression level in breast cancer tissues and tumor response to chemotherapy. Furthermore, increased cirExo-TRPC5 level after chemotherapy preceded progressive disease (PD) based on imaging examination and strongly predicted acquired chemoresistance. Taken together, our study demonstrated that cirExo-TRPC5 might act as a noninvasive chemoresistance marker and might serve as an adjuvant to the current imaging examination-based chemoresistance.