Cancer-associated fibroblast-derived exosomal microRNA-20a suppresses the PTEN/PI3K-AKT pathway to promote the progression and chemoresistance of non-small cell lung cancer

Exosome-mediated transfer of circRNA563 promoting hepatocellular carcinoma by targeting the microRNA148a-3p/metal-regulatory transcription factor-1 pathway

BACKGROUND

Mesenchymal stem cells (MSCs) exert anti-oncogenic effects via exosomes containing non-coding RNA (ncRNA), which play important roles in tumor biology. Our preliminary study identified the interaction of the ncRNA hsa_circ_0000563 (circ563) and the circ563-associated miR-148a-3p in exosomes, as miR-148a-3p and its target metal-regulatory transcription factor-1 (MTF-1) are implicated in hepatocellular carcinoma (HCC) progression.

AIM

To identify the clinical significance, functional implications, and mechanisms of circ563 in HCC.

METHODS

The expression levels of miR-148a-3p and MTF-1 in exosomes derived from MSC and HCC cells were compared, and their effects on HCC cells were assessed. Using a dual-luciferase reporter assay, miR-148a-3p was identified as an associated microRNA of circ563, whose role in HCC regulation was assessed in vitro and in vivo.

RESULTS

The silencing of circ563 blocked the HCC cell proliferation and invasion and induced apoptosis. Co-culturing of HCC cells with MSC-derived exosomes following circ563 overexpression promoted cell proliferation and metastasis and elicited changes in miR-148a-3p and MTF-1 expression. The tumor-promoting effects of circ563 were partially suppressed by miR-148a-3p overexpression or MTF-1 depletion. Xenograft experiments performed in nude mice confirmed that circ563-enriched exosomes facilitated tumor growth by upregulating the expression of MTF-1. In HCC tissues, circ563 expression was negatively correlated with miR-148a-3p expression but positively correlated with MTF-1 levels.

CONCLUSION

MSCs may exhibit anti-HCC activity through the exosomal circ563/miR-148a-3p/MTF-1 pathway, while exosomes can transmit circ563 to promote oncogenic behavior by competitively binding to miR-148a-3p to activate MTF-1.

miR-195-5p as Regulator of γ-Catenin and Desmosome Junctions in Colorectal Cancer

Desmosomes play a key role in the regulation of cell adhesion and signaling. Dysregulation of the desmosome complex is associated with the loss of epithelial cell polarity and disorganized tissue architecture typical of colorectal cancer (CRC). The aim of this study was to investigate and characterize the effect of miR-195-5p on desmosomal junction regulation in CRC. In detail, we proposed to investigate the deregulation of miR-195-5p and JUP, a gene target that encodes a desmosome component in CRC patients. JUP closely interacts with desmosomal cadherins, and downstream, it regulates several intracellular transduction factors. We restored the miR-195-5p levels by transient transfection in colonic epithelial cells to examine the effects of miR-195-5p on JUP mRNA and protein expression. The JUP regulation by miR-195-5p, in turn, determined a modulation of desmosome cadherins (Desmoglein 2 and Desmocollin 2). Furthermore, we focused on whether the miR-195-5p gain of function was also able to modulate the expression of key components of Wnt signaling, such as NLK, LEF1 and Cyclin D1. In conclusion, we have identified a novel mechanism controlled by miR-195-5p in the regulation of adhesive junctions, suggesting its potential clinical relevance for future miRNA-based therapy in CRC.

Survivin degradation by bergenin overcomes pemetrexed resistance

PURPOSE

Chemoresistance is a primary factor for treatment failure and tumor recurrence in non-small cell lung cancer (NSCLC) patients. The oncoprotein survivin is commonly upregulated in human malignancies and is associated with poor prognosis, but its effect on carcinogenesis and chemoresistance in NSCLC is not yet evident, and to explore an effective inhibitor targeting survivin expression is urgently needed.

METHODS

The protumor characteristics of survivin and antitumor activities of bergenin in NSCLC cells were examined by MTS, colony formation assays, immunoblot, immunohistochemistry, and in vivo xenograft development.

RESULTS

Survivin was upregulated in non-small cell lung cancer (NSCLC) tissues, while its depletion inhibited NSCLC tumorigenesis. The current study focused on bergenin, identifying its effective antitumor effect on NSCLC cells both in vivo and in vitro. The results showed that bergenin could inhibit cell proliferation and induce the intrinsic pathway of apoptosis via downregulating survivin. Mechanistically, bergenin reduced the phosphorylation of survivin via inhibiting the Akt/Wee1/CDK1 signaling pathway, thus resulting in enhanced interaction between survivin and E3 ligase Fbxl7 to promote survivin ubiquitination and degradation. Furthermore, bergenin promoted chemoresistance in NSCLC cells re-sensitized to pemetrexed treatment.

CONCLUSIONS

Survivin overexpression is required for maintaining multiple malignant phenotypes of NSCLC cells. Bergenin exerts a potent antitumor effect on NSCLC via targeting survivin, rendering it a promising agent for the treatment of NSCLC.

Composition of Conditioned Media from Radioresistant and Chemoresistant Cancer Cells Reveals miRNA and Other Secretory Factors Implicated in the Development of Resistance

Resistance to chemo- or radiotherapy is the main obstacle to consistent treatment outcomes in oncology patients. A deeper understanding of the mechanisms driving the development of resistance is required. This review focuses on secretory factors derived from chemo- and radioresistant cancer cells, cancer-associated fibroblasts (CAFs), mesenchymal stem cells (MSCs), and cancer stem cells (CSCs) that mediate the development of resistance in unexposed cells. The first line of evidence considers the experiments with conditioned media (CM) from chemo- and radioresistant cells, CAFs, MSCs, and CSCs that elevate resistance upon the ionizing radiation or anti-cancer drug exposure of previously untreated cells. The composition of CM revealed factors such as circular RNAs; interleukins; plasminogen activator inhibitor; and oncosome-shuttled lncRNAs, mRNAs, and miRNAs that aid in cellular communication and transmit signals inducing the chemo- and radioresistance of sensitive cancer cells. Data, demonstrating that radioresistant cancer cells become resistant to anti-neoplastic drug exposure and vice versa, are also discussed. The mechanisms driving the development of cross-resistance between chemotherapy and radiotherapy are highlighted. The secretion of resistance-mediating factors to intercellular fluid and blood brings attention to its diagnostic potential. Highly stable serum miRNA candidates were proposed by several studies as prognostic markers of radioresistance; however, clinical studies are needed to validate their utility. The ability to predict a treatment response with the help of the miRNA resistance status database will help with the selection of an effective therapeutic strategy. The possibility of miRNA-based therapy is currently being investigated with ongoing clinical studies, and such approaches can be used to alleviate resistance in oncology patients.

Hyaluronic acid-empowered nanotheranostics in breast and lung cancers therapy

Nanomedicine application in cancer therapy is an urgency because of inability of current biological therapies for complete removal of tumor cells. The development of smart and novel nanoplatforms for treatment of cancer can provide new insight in tumor suppression. Hyaluronic acid is a biopolymer that can be employed for synthesis of smart nanostructures capable of selective targeting CD44-overexpressing tumor cells. The breast and lung cancers are among the most malignant and common tumors in both females and males that environmental factors, lifestyle and genomic alterations are among the risk factors for their pathogenesis and development. Since etiology of breast and lung tumors is not certain and multiple factors participate in their development, preventative measures have not been completely successful and studies have focused on developing new treatment strategies for them. The aim of current review is to provide a comprehensive discussion about application of hyaluronic acid-based nanostructures for treatment of breast and lung cancers. The main reason of using hyaluronic acid-based nanoparticles is their ability in targeting breast and lung cancers in a selective way due to upregulation of CD44 receptor on their surface. Moreover, nanocarriers developed from hyaluronic acid or functionalized with hyaluronic acid have high biocompatibility and their safety is appreciated. The drugs and genes used for treatment of breast and lung cancers lack specific accumulation at cancer site and their cytotoxicity is low, but hyaluronic acid-based nanostructures provide their targeted delivery to tumor site and by increasing internalization of drugs and genes in breast and lung tumor cells, they improve their therapeutic index. Furthermore, hyaluronic acid-based nanostructures can be used for phototherapy-mediated breast and lung cancers ablation. The stimuli-responsive and smart kinds of hyaluronic acid-based nanostructures such as pH- and light-responsive can increase selective targeting of breast and lung cancers.

Non-coding RNAs' function in cancer development, diagnosis and therapy

While previous research on cancer biology has focused on genes that code for proteins, in recent years it has been discovered that non-coding RNAs (ncRNAs)play key regulatory roles in cell biological functions. NcRNAs account for more than 95% of human transcripts and are an important entry point for the study of the mechanism of cancer development. An increasing number of studies have demonstrated that ncRNAs can act as tumor suppressor genes or oncogenes to regulate tumor development at the epigenetic level, transcriptional level, as well as post-transcriptional level. Because of the importance of ncRNAs in cancer, most clinical trials have focused on ncRNAs to explore whether ncRNAs can be used as new biomarkers or therapies. In this review, we focus on recent studies of ncRNAs including microRNAs (miRNAs), long ncRNAs (lncRNAs), circle RNAs (circRNAs), PIWI interacting RNAs (piRNAs), and tRNA in different types of cancer and explore the application of these ncRNAs in the development of cancer and the identification of relevant therapeutic targets and tumor biomarkers. Graphical abstract drawn by Fidraw.

Cisplatin-activated ERβ/DCAF8 positive feedback loop induces chemoresistance in non-small cell lung cancer via PTEN/Akt axis

High levels of the estrogen receptor β (ERβ) predict poor prognosis following platinum-containing adjuvant chemotherapies in patients with non-small cell lung cancer (NSCLC). However, the precise role of ERβ remains elusive. In this study, we demonstrated that targeting ERβ could significantly increase the cytotoxicity of cisplatin both in vitro and in vivo. Mechanically, cisplatin directly binds to ERβ, which facilitates its homodimerization and nuclear translocation. ERβ activation transcriptionally represses the expression of DCAF8, an adaptor of CRL4 E3 ubiquitin ligase, which in turn attenuates the proteasomal degradation of ERβ, leading to ERβ accumulation; this positive feedback loop results in Akt activation and eventually cisplatin resistance in NSCLC through PTEN inhibition. Moreover, low expression of DCAF8 and high expression of ERβ are associated with treatment resistance in patients receiving cisplatin-containing adjuvant chemotherapy. The present results provide insights into the underlying mechanism of ERβ-induced cisplatin resistance and offer an alternative therapeutic strategy to improve the efficacy of platinum-based chemotherapy in patients with NSCLC.

Exosomes-regulated lipid metabolism in tumorigenesis and cancer progression

Increasing evidence highlights the role of lipid metabolism in tumorigenesis and tumor progression. Targeting the processes of lipid metabolism, including lipogenesis, lipid uptake, fatty acid oxidation, and lipolysis, is an optimal strategy for anti-cancer therapy. Beyond cell-cell membrane surface interaction, exosomes are pivotal factors that transduce intercellular signals in the tumor microenvironment (TME). Most research focuses on the role of lipid metabolism in regulating exosome biogenesis and extracellular matrix (ECM) remodeling. The mechanisms of exosome and ECM-mediated reprogramming of lipid metabolism are currently unclear. We summarize several mechanisms associated with the regulation of lipid metabolism in cancer, including transport of exosomal carriers and membrane receptors, activation of the PI3K pathway, ECM ligand-receptor interactions, and mechanical stimulation. This review aims to highlight the significance of these intercellular factors in TME and to deepen the understanding of the functions of exosomes and ECM in the regulation of lipid metabolism.

Role of miR‑181a‑5p in cancer (Review)

MicroRNAs (miRNAs) are non‑coding RNAs (ncRNAs) that can post‑transcriptionally suppress targeted genes. Dysregulated miRNAs are associated with a variety of diseases. MiR‑181a‑5p is a conserved miRNA with the ability to regulate pathological processes, such as angiogenesis, inflammatory response and obesity. Numerous studies have demonstrated that miR‑181a‑5p exerts regulatory influence on cancer development and progression, acting as an oncomiR or tumor inhibitor in various cancer types by impacting multiple hallmarks of tumor. Generally, miR‑181a‑5p binds to target RNA sequences with partial complementarity, resulting in suppression of the targeted genes of miR‑181a‑5p. However, the precise role of miR‑181a‑5p in cancer remains incompletely understood. The present review aims to provide a comprehensive summary of recent research on miR‑181a‑5p, focusing on its involvement in different types of cancer and its potential as a diagnostic and prognostic biomarker, as well as its function in chemoresistance.

Dysregulated Signalling Pathways Driving Anticancer Drug Resistance

One of the leading causes of death worldwide, in both men and women, is cancer. Despite the significant development in therapeutic strategies, the inevitable emergence of drug resistance limits the success and impedes the curative outcome. Intrinsic and acquired resistance are common mechanisms responsible for cancer relapse. Several factors crucially regulate tumourigenesis and resistance, including physical barriers, tumour microenvironment (TME), heterogeneity, genetic and epigenetic alterations, the immune system, tumour burden, growth kinetics and undruggable targets. Moreover, transforming growth factor-beta (TGF-β), Notch, epidermal growth factor receptor (EGFR), integrin-extracellular matrix (ECM), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), phosphoinositol-3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR), wingless-related integration site (Wnt/β-catenin), Janus kinase/signal transducers and activators of transcription (JAK/STAT) and RAS/RAF/mitogen-activated protein kinase (MAPK) signalling pathways are some of the key players that have a pivotal role in drug resistance mechanisms. To guide future cancer treatments and improve results, a deeper comprehension of drug resistance pathways is necessary. This review covers both intrinsic and acquired resistance and gives a comprehensive overview of recent research on mechanisms that enable cancer cells to bypass barriers put up by treatments, and, like "satellite navigation", find alternative routes by which to carry on their "journey" to cancer progression.

Exosomal circRNA: emerging insights into cancer progression and clinical application potential

Exosomal circRNA serves a novel genetic information molecule, facilitating communication between tumor cells and microenvironmental cells, such as immune cells, fibroblasts, and other components, thereby regulating critical aspects of cancer progression including immune escape, tumor angiogenesis, metabolism, drug resistance, proliferation and metastasis. Interestingly, microenvironment cells have new findings in influencing tumor progression and immune escape mediated by the release of exosomal circRNA. Given the intrinsic stability, abundance, and broad distribution of exosomal circRNAs, they represent excellent diagnostic and prognostic biomarkers for liquid biopsy. Moreover, artificially synthesized circRNAs may open up new possibilities for cancer therapy, potentially bolstered by nanoparticles or plant exosome delivery strategies. In this review, we summarize the functions and underlying mechanisms of tumor cell and non-tumor cell-derived exosomal circRNAs in cancer progression, with a special focus on their roles in tumor immunity and metabolism. Finally, we examine the potential application of exosomal circRNAs as diagnostic biomarkers and therapeutic targets, highlighting their promise for clinical use.

Functional role of MicroRNA/PI3K/AKT axis in osteosarcoma

Osteosarcoma (OS) is a primary malignant bone tumor that occurs in children and adolescents, and the PI3K/AKT pathway is overactivated in most OS patients. MicroRNAs (miRNAs) are highly conserved endogenous non-protein-coding RNAs that can regulate gene expression by repressing mRNA translation or degrading mRNA. MiRNAs are enriched in the PI3K/AKT pathway, and aberrant PI3K/AKT pathway activation is involved in the development of osteosarcoma. There is increasing evidence that miRNAs can regulate the biological functions of cells by regulating the PI3K/AKT pathway. MiRNA/PI3K/AKT axis can regulate the expression of osteosarcoma-related genes and then regulate cancer progression. MiRNA expression associated with PI3K/AKT pathway is also clearly associated with many clinical features. In addition, PI3K/AKT pathway-associated miRNAs are potential biomarkers for osteosarcoma diagnosis, treatment and prognostic assessment. This article reviews recent research advances on the role and clinical application of PI3K/AKT pathway and miRNA/PI3K/AKT axis in the development of osteosarcoma.

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.

Exosomal miRNAs in the Tumor Microenvironment of Multiple Myeloma

Multiple myeloma (MM) is a malignancy of plasma cells in the bone marrow and is characterized by the clonal proliferation of B-cells producing defective monoclonal immunoglobulins. Despite the latest developments in treatment, drug resistance remains one of the major challenges in the therapy of MM. The crosstalk between MM cells and other components within the bone marrow microenvironment (BME) is the major determinant of disease phenotypes. Exosomes have emerged as the critical drivers of this crosstalk by allowing the delivery of informational cargo comprising multiple components from miniature peptides to nucleic acids. Such material transfers have now been shown to perpetuate drug-resistance development and disease progression in MM. MicroRNAs(miRNAs) specifically play a crucial role in this communication considering their small size that allows them to be readily packed within the exosomes and widespread potency that impacts the developmental trajectory of the disease inside the tumor microenvironment (TME). In this review, we aim to provide an overview of the current understanding of the role of exosomal miRNAs in the epigenetic modifications inside the TME and its pathogenic influence on the developmental phenotypes and prognosis of MM.

Cancer-associated fibroblasts suppress ferroptosis and induce gemcitabine resistance in pancreatic cancer cells by secreting exosome-derived ACSL4-targeting miRNAs

BACKGROUND

Pancreatic cancer continues to be one of the world's most lethal cancers. Chemotherapy resistance in patients with advanced pancreatic cancer often accompany with dismal prognosis, highlighting the need to investigate mechanisms of drug resistance and develop therapies to overcome chemoresistance.

METHODS

This research was filed with the Chinese Clinical Trial Registry (ChiCTR2200061320). In order to isolate primary normal fibroblasts (NFs) and cancer-associated fibroblasts (CAFs) samples of pancreatic ductal adenocarcinoma (PDAC) and paracancerous pancreatic tissue from individuals diagnosed with PDAC were obtained. The exosomes were obtained using ultracentrifugation, and their characteristics were determined by Western blotting, nanoparticle tracking analysis, and transmission electron microscopy. CAF-derived miRNAs were analyzed by RT-qPCR and high-throughput sequencing. Gemcitabine (GEM) was employed to promote ferroptosis, and ferroptosis levels were determined by monitoring lipid reactive oxygen species (ROS), cell survival, and intracellular Fe²⁺ concentrations. To assess in vivo tumor response to GEM therapy, a xenograft tumor mouse model was utilized.

RESULTS

Exosomes derived from CAFs in PDAC did not exhibit innate GEM resistance. CAFs promoted chemoresistance in PDAC cells following GEM treatment by secreting exosomes, and maintaining signaling communication with cancer cells. Mechanistically, miR-3173-5p derived from CAF exosomes sponged ACSL4 and inhibited ferroptosis after uptake by cancer cells.

CONCLUSION

This work demonstrates a novel mode of acquired chemoresistance in PDAC and identifies the miR-3173-5p/ACSL4 pathway as a promising treatment target for GEM-resistant pancreatic cancer.

Cancer-associated fibroblast-derived exosome miR-181b-3p promotes the occurrence and development of colorectal cancer by regulating SNX2 expression

Tumor microenvironment (TME) (e.g., stromal cells) has been closely related to the pathological process of colorectal cancer (CRC). In TME, tumor-associated fibroblasts (CAFs) are the main stromal cells. The studies have showed that CAFs promoted tumor growth and metastasis in CRC and led to poor prognosis. Mounting evidence indicates that CAFs-mediated exosomes regulate the pathological process of neighboring tumor cells through the transmission of miRNAs. In our study, we aimed to explore the function of CAFs-derived exosome miR-181b-3p in CRC. First, the expression of miR-181b-3p in CRC was found to be up-regulated and its expression was dramatically up-regulated in CRC cells after co-incubation of CAFs-mediated exosomes with CRC cells. Then, it was found that the CAFs-derived exosomes were markedly enhanced the proliferation and migration of the CRC cells, and substantially reduced apoptosis. To elucidate the influence of CAFs-derived exosome miR-181b-3p on CRC, we overexpressed and knocked down the miR-181b-3p expression in CAFs, respectively. It was found that miR-181b-3p significantly increased the proliferation and migration of CRC cells. Furthermore, we conducted in vivo experiments. Finally, we demonstrated that CAF-derived exosome miR-181b-3p regulated sorting nexin 2 (SNX2) expression in CRC cells by bioinformatics prediction combined with luciferase reporter assay. Further cellular and animal experiments jointly elucidated that miR-181b-3p promoted the pathological process of CRC by SNX2 expression. In brief, our results demonstrated that CAFs-derived exosome miR-181b-3p promoted the pathogenesis of CRC by regulating SNX2 expression, which provides a novel idea for CRC treatment.

Extracellular Vesicles: New Classification and Tumor Immunosuppression

Extracellular vesicles (EVs) are cell-derived membrane-surrounded vesicles carrying various types of molecules. These EV cargoes are often used as pathophysiological biomarkers and delivered to recipient cells whose fates are often altered in local and distant tissues. Classical EVs are exosomes, microvesicles, and apoptotic bodies, while recent studies discovered autophagic EVs, stressed EVs, and matrix vesicles. Here, we classify classical and new EVs and non-EV nanoparticles. We also review EVs-mediated intercellular communication between cancer cells and various types of tumor-associated cells, such as cancer-associated fibroblasts, adipocytes, blood vessels, lymphatic vessels, and immune cells. Of note, cancer EVs play crucial roles in immunosuppression, immune evasion, and immunotherapy resistance. Thus, cancer EVs change hot tumors into cold ones. Moreover, cancer EVs affect nonimmune cells to promote cellular transformation, including epithelial-to-mesenchymal transition (EMT), chemoresistance, tumor matrix production, destruction of biological barriers, angiogenesis, lymphangiogenesis, and metastatic niche formation.

Therapeutic Targeting of Cancer-Associated Fibroblasts in the Non-Small Cell Lung Cancer Tumor Microenvironment

Lung cancer is the most frequently diagnosed cancer and the leading cause of cancer death worldwide. The most common lung cancer is non-small cell lung cancer (NSCLC), with an overall 5-year survival rate of around 20% because NSCLC is a metastatic disease. A better understanding of the mechanism underlying lung cancer metastasis is therefore urgently needed. The tumor microenvironment involves different types of stromal cells and functions as key components in the progression of NSCLC. Through epithelial-mesenchymal transition (EMT), in which epithelial cells lose their polarity and acquire mesenchymal potential, cancer cells acquire metastatic abilities, as well as cancer stem-cell-like potential. We previously reported that cancer-associated fibroblasts (CAFs) interact with lung cancer cells to allow for the acquisition of malignancy and treatment resistance by paracrine loops via EMT signals in the tumor microenvironment. Furthermore, CAFs regulate the cytotoxic activity of immune cells via various cytokines and chemokines, creating a microenvironment of immune tolerance. Regulation of CAFs can therefore affect immune responses. Recent research has shown several roles of CAFs in NSCLC tumorigenesis, owing to their heterogeneity, so molecular markers of CAFs should be elucidated to better classify tumor-promoting subtypes and facilitate the establishment of CAF-specific targeted therapies. CAF-targeted cancer treatments may suppress EMT and regulate the niche of cancer stem cells and the immunosuppressive network and thus may prove useful for NSCLC treatment through multiple mechanisms.

Modulating Effects of Cancer-Derived Exosomal miRNAs and Exosomal Processing by Natural Products

Cancer-derived exosomes exhibit sophisticated functions, such as proliferation, apoptosis, migration, resistance, and tumor microenvironment changes. Several clinical drugs modulate these exosome functions, but the impacts of natural products are not well understood. Exosome functions are regulated by exosome processing, such as secretion and assembly. The modulation of these exosome-processing genes can exert the anticancer and precancer effects of cancer-derived exosomes. This review focuses on the cancer-derived exosomal miRNAs that regulate exosome processing, acting on the natural-product-modulating cell functions of cancer cells. However, the role of exosomal processing has been overlooked in several studies of exosomal miRNAs and natural products. In this study, utilizing the bioinformatics database (miRDB), the exosome-processing genes of natural-product-modulated exosomal miRNAs were predicted. Consequently, several natural drugs that modulate exosome processing and exosomal miRNAs and regulate cancer cell functions are described here. This review sheds light on and improves our understanding of the modulating effects of exosomal miRNAs and their potential exosomal processing targets on anticancer treatments based on the use of natural products.

Exosomal epidermal growth factor receptor is involved in HPV-16 E7-induced epithelial-mesenchymal transition of non-small cell lung cancer cells: A driver of signaling in vivo?

Our previous studies have demonstrated that human papillomavirus (HPV)-16 E7 oncoprotein promoted epithelial-mesenchymal transition (EMT) in non-small cell lung cancer (NSCLC) cells. Moreover, recent studies have found that exosomes can mediate EMT of NSCLC cells and epidermal growth factor receptor (EGFR) is related to the progression of NSCLC. Here, we further investigated the role of exosomal EGFR in HPV-16 E7-induced EMT of NSCLC cells. Our results showed that the exosomes derived from the stable HPV-16 E7-overexpressing A549 and NCI-H460 NSCLC cells (E7 Exo) significantly increased migration, invasion, and proliferation abilities of NSCLC cells as compared with the exosomes derived from empty vector-infected NSCLC cells (ev Exo). Moreover, both in vitro and in vivo results demonstrated that E7 Exo dramatically enhanced EMT of NSCLC cells and promoted the growth of subcutaneous NSCLC xenografts. Additionally, HPV-16 E7 enhanced the expression of EGFR and p-EGFR in both NSCLC cells and exosomes. Furthermore, the inhibition of EGFR activation or exosome secretion suppressed E7 Exo-induced migration, invasion, and EMT of NSCLC. Moreover, 12 kinds of differentially expressed miRNAs between E7 Exo and ev Exo (fold change≥2, P ≤ .05) were screened out, of which 7 miRNAs were up-regulated while 5 miRNAs were down-regulated in A549 E7 Exo. Taken together, our findings suggest that exosomal EGFR is involved in HPV-16 E7-induced EMT of NSCLC cells, which may play a key role in the progression of HPV-related NSCLC.

Extracellular Vesicles in Cancer Drug Resistance: Roles, Mechanisms, and Implications

Extracellular vesicles (EVs) are cell-derived nanosized vesicles that mediate cell-to-cell communication via transporting bioactive molecules and thus are critically involved in various physiological and pathological conditions. EVs contribute to different aspects of cancer progression, such as cancer growth, angiogenesis, metastasis, immune evasion, and drug resistance. EVs induce the resistance of cancer cells to chemotherapy, radiotherapy, targeted therapy, antiangiogenesis therapy, and immunotherapy by transferring specific cargos that affect drug efflux and regulate signaling pathways associated with epithelial-mesenchymal transition, autophagy, metabolism, and cancer stemness. In addition, EVs modulate the reciprocal interaction between cancer cells and noncancer cells in the tumor microenvironment (TME) to develop therapy resistance. EVs are detectable in many biofluids of cancer patients, and thus are regarded as novel biomarkers for monitoring therapy response and predicting prognosis. Moreover, EVs are suggested as promising targets and engineered as nanovehicles to deliver drugs for overcoming drug resistance in cancer therapy. In this review, the biological roles of EVs and their mechanisms of action in cancer drug resistance are summarized. The preclinical studies on using EVs in monitoring and overcoming cancer drug resistance are also discussed.

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.

Irradiation enhances the malignancy-promoting behaviors of cancer-associated fibroblasts

Background

Cancer-associated fibroblasts (CAFs) are the important component of the tumor microenvironment (TME). Previous studies have found that some pro-malignant CAFs participate in the resistance to radiotherapy as well as the initiation and progression of tumor recurrence. However, the exact mechanism of how radiation affects CAFs remains unclear. This study aimed to explore the effect and possible mechanism of radiation-activated CAFs, and its influence on lung cancer.

Methods

CAFs were isolated from surgical specimens in situ and irradiated with 8Gy x-rays. The changes in cell morphology and subcellular structure were observed. CAFs marker proteins such as FAP and α-SMA were detected by Western Blotting. Cell counting kit-8 (CCK8) assay, flow cytometry, wound healing assay, and transwell chamber assay was used to detect the activation of cell viability and migration ability. A nude mouse xenograft model was established to observe the tumorigenicity of irradiated CAFs in vivo. The genomic changes of CAFs after radiation activation were analyzed by transcriptome sequencing technology, and the possible mechanisms were analyzed.

Results

The CAFs showed a disorderly growth pattern after X-ray irradiation. Subcellular observations suggested that metabolism-related organelles exhibited more activity. The expression level of CAFs-related signature molecules was also increased. The CAFs irradiated by 8Gy had good proliferative activity. In the (indirect) co-culture system, CAFs showed radiation protection and migration induction to lung cancer cell lines, and this influence was more obvious in radiation-activated CAFs. The radiation protection was decreased after exosome inhibitors were applied. Vivo study also showed that radiation-activated CAFs have stronger tumorigenesis. Transcriptome analysis showed that genes were enriched in several pro-cancer signaling pathways in radiation-activated CAFs.

Conclusions

Our study confirmed that CAFs could be activated by ionizing radiation. Irradiation-activated CAFs could promote cancer cell proliferation, migration, radiotherapy tolerance, and tumorigenesis. These results suggested that irradiation-activated CAFs might participate in the recurrence of lung cancer after radiotherapy, and the inhibition of CAFs activation may be an important way to improve clinical radiotherapy efficacy.

Exosomal miR92a Promotes Cytarabine Resistance in Myelodysplastic Syndromes by Activating Wnt/β-catenin Signal Pathway

Cytarabine (Ara-C) has been one of the frontline therapies for clonal hematopoietic stem cell disorders, such as myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), but Ara-C resistance often occurs and leads to treatment failure. Exosomal microRNAs (miRNAs, miRs) as small noncoding RNA that play important roles in post-transcriptional gene regulation, can be delivered into recipient cells by exosomes and regulate target genes' expression. miR92a has been reported to be dysregulated in many cancers, including MDS and AML. However, the effects of exosomal miR92a in hematologic malignancies have not been fully investigated. In this study, qualitative analysis showed the significantly enhanced expression of exosomal miR92a in MDS/AML plasma. Subsequent functional assays indicated that exosomal miR92a can be transported and downregulate PTEN in recipient cells and, furthermore, activate the Wnt/β-catenin signaling pathway and interfere with the Ara-C resistance of receipt MDS/AML cells in vitro and in vivo. Altogether, our findings offer novel insights into plasma exosomal miR92a participating in Ara-C resistance in MDS/AML and we propose miR92a as a potential therapeutic target for MDS/AML.