Vascular endothelial cell-derived exosomal miR-30a-5p inhibits lung adenocarcinoma malignant progression by targeting CCNE2

Tumor-suppressive action of miR-30a-5p in lung adenocarcinoma correlates with ABL2 inhibition and PI3K/AKT pathway inactivation

INTRODUCTION

ABL2 contributes to the oncogenic potential of cancers, pointing to its inhibition as a possible strategy against malignant diseases. Bioinformatics prediction of upstream effector miR-30a-5p for ABL2 allowed us to hypothesize and then validate mechanistic actions of miR-30a-5p in lung adenocarcinoma (LUAD).

MATERIALS AND METHODS

The ABL2 expression in LUAD was analyzed in the TCGA data, clinical samples, and cell lines. The shRNA-mediated silencing of ABL2 was introduced to illustrate its effect on malignant phenotypes of LUAD cells. The binding affinity between ABL2 and miR-30a-5p was verified by luciferase activity and RNA pull-down assay. Ectopic expression, knockdown methods, and PI3K inhibitor LY294002 were used to investigate their effects on in vitro biological characteristics and in vivo tumor growth of LUAD cells. Using nude mouse lung adenocarcinoma in situ and brain metastasis models to validate the inhibitory effect of miR-30a-5p on LUAD by regulating the ABL2/PI3K/AKT signaling axis.

RESULTS

High expression of ABL2 and poor expression of miR-30a-5p were noticed in LUAD tissues and cell lines. Importantly, miR-30a-5p was demonstrated to target and downregulate ABL2, subsequently inactivating the PI3K/AKT pathway. miR-30a-5p inhibited the malignant phenotypes of LUAD cells by inhibiting ABL2 expression and inactivating the PI3K/AKT pathway. For in vivo experiments, miR-30a-5p was substantiated to thwart tumor tumorigenesis by regulating the ABL2/PI3K/AKT axis. In addition, miR-30a-5p suppresses the occurrence and development of in situ lung cancer and brain metastasis via the ABL2/PI3K/AKT signaling pathway.

CONCLUSION

This study underscores the inhibitory role of miR-30a-5p in LUAD through the ABL2/PI3K/AKT axis, which may be a viable target for LUAD treatment.

MiRNA-30a-5p/VCAN Arrests Tumor Metastasis via Modulating the Adhesion of Lung Adenocarcinoma Cells

Previous research indicated that the dysregulation of miRNA-30a-5p has a correlation with cell metastasis of lung adenocarcinoma (LUAD). But the study about the molecular regulatory mechanism of miRNA-30a-5p in LUAD cell metastasis is limited. Thus, we discussed the mechanism of miRNA-30a-5p and its biological function in LUAD cells. By utilizing bioinformatics analysis, how miRNA-30a-5p was expressed in LUAD tissue was determined and its downstream target genes were predicted. The signaling pathways where these target genes enriched were analyzed. Several in vitro experiments were applied for cell function detection: dual-luciferase assay for validating the targeting relationship between miRNA-30a-5p and its target gene; quantitative real-time polymerase chain reaction for testing the expression of miRNA-30a-5p and its target gene in LUAD cells; MTT, transwell, cell adhesion, flow cytometry and immunofluorescence assays for examining the capabilities of LUAD cells to proliferate, migrate, invade, adhere, apoptosis and epithelial-mesenchymal transition (EMT) effect; Western blot for determining the expression of adhesion-related proteins and EMT-related proteins. Down-regulated miRNA-30a-5p was discovered in LUAD cells, but on the contrary, VCAN was upregulated. MiRNA-30a-5p overexpression notably repressed the virulent progression of LUAD cells. Besides, dual-luciferase assay validated the targeting relationship between miRNA-30a-5p and VCAN. MiRNA-30a-5p, by negatively regulating VCAN, was capable of hindering LUAD cell proliferation, migration, invasion, adhesion, viability and EMT. It was illustrated that miRNA-30a-5p could downregulate VCAN to retard the malignant progression of LUAD cells, which provides novel insights into LUAD pathogenesis, suggesting that miRNA-30a-5p/VCAN axis can be a promising anti-cancer target for LUAD.

Potential roles of exosomes in the initiation and metastatic progression of lung cancer

Lung cancer (LC) incidence and mortality continue to increase annually worldwide. LC is insidious and readily metastasizes and relapses. Except for its early diagnosis and surgical resection, there is no effective cure for advanced metastatic LC, and the prognosis remains dismal. Exosomes, a class of nano-sized extracellular vesicles produced by healthy or diseased cells, are coated with a bilayer lipid membrane and contain various functional molecules such as proteins, lipids, and nucleic acids. They can be used for intracellular or intercellular signaling or the transportation of biological substances. A growing body of evidence supports that exosomes play multiple crucial roles in the occurrence and metastatic progression of many malignancies, including LC. The elucidation of the potential roles of exosomes in the initiation, invasion, and metastasis of LC and their underlying molecular mechanisms may contribute to improved early diagnosis and treatment.

Emerging role of exosome-derived non-coding RNAs in tumor-associated angiogenesis of tumor microenvironment

The tumor microenvironment (TME) is an intricate ecosystem that is actively involved in various stages of cancer occurrence and development. Some characteristics of tumor biological behavior, such as proliferation, migration, invasion, inhibition of apoptosis, immune escape, angiogenesis, and metabolic reprogramming, are affected by TME. Studies have shown that non-coding RNAs, especially long-chain non-coding RNAs and microRNAs in cancer-derived exosomes, facilitate intercellular communication as a mechanism for regulating angiogenesis. They stimulate tumor growth, as well as angiogenesis, metastasis, and reprogramming of the TME. Exploring the relationship between exogenous non-coding RNAs and tumor-associated endothelial cells, as well as their role in angiogenesis, clinicians will gain new insights into treatment as a result.

Connection between Radiation-Regulating Functions of Natural Products and miRNAs Targeting Radiomodulation and Exosome Biogenesis

Exosomes are cell-derived membranous structures primarily involved in the delivery of the payload to the recipient cells, and they play central roles in carcinogenesis and metastasis. Radiotherapy is a common cancer treatment that occasionally generates exosomal miRNA-associated modulation to regulate the therapeutic anticancer function and side effects. Combining radiotherapy and natural products may modulate the radioprotective and radiosensitizing responses of non-cancer and cancer cells, but there is a knowledge gap regarding the connection of this combined treatment with exosomal miRNAs and their downstream targets for radiation and exosome biogenesis. This review focuses on radioprotective natural products in terms of their impacts on exosomal miRNAs to target radiation-modulating and exosome biogenesis (secretion and assembly) genes. Several natural products have individually demonstrated radioprotective and miRNA-modulating effects. However, the impact of natural-product-modulated miRNAs on radiation response and exosome biogenesis remains unclear. In this review, by searching through PubMed/Google Scholar, available reports on potential functions that show radioprotection for non-cancer tissues and radiosensitization for cancer among these natural-product-modulated miRNAs were assessed. Next, by accessing the miRNA database (miRDB), the predicted targets of the radiation- and exosome biogenesis-modulating genes from the Gene Ontology database (MGI) were retrieved bioinformatically based on these miRNAs. Moreover, the target-centric analysis showed that several natural products share the same miRNAs and targets to regulate radiation response and exosome biogenesis. As a result, the miRNA-radiomodulation (radioprotection and radiosensitization)-exosome biogenesis axis in regard to natural-product-mediated radiotherapeutic effects is well organized. This review focuses on natural products and their regulating effects on miRNAs to assess the potential impacts of radiomodulation and exosome biogenesis for both the radiosensitization of cancer cells and the radioprotection of non-cancer cells.

Evaluation and Application of Drug Resistance by Biomarkers in the Clinical Treatment of Liver Cancer

Liver cancer is one of the most lethal cancers in the world, mainly owing to the lack of effective means for early monitoring and treatment. Accordingly, there is considerable research interest in various clinically applicable methods for addressing these unmet needs. At present, the most commonly used biomarker for the early diagnosis of liver cancer is alpha-fetoprotein (AFP), but AFP is sensitive to interference from other factors and cannot really be used as the basis for determining liver cancer. Treatment options in addition to liver surgery (resection, transplantation) include radiation therapy, chemotherapy, and targeted therapy. However, even more expensive targeted drug therapies have a limited impact on the clinical outcome of liver cancer. One of the big reasons is the rapid emergence of drug resistance. Therefore, in addition to finding effective biomarkers for early diagnosis, an important focus of current discussions is on how to effectively adjust and select drug strategies and guidelines for the treatment of liver cancer patients. In this review, we bring this thought process to the drug resistance problem faced by different treatment strategies, approaching it from the perspective of gene expression and molecular biology and the possibility of finding effective solutions.

Exosomal transfer of miR-195-5p restrains lung adenocarcinoma progression

Exosome is an important way for tumor cells to communicate with other cells and plays an important role in tumor progression. Previous studies revealed that miR-195-5p acts as a tumor suppressor in lung cancer. However, the role and molecular mechanism of exosomal transferred miR-195-5p in lung adenocarcinoma (LAC) remains unknown. Here, we found that miR-195-5p expression in circulating exosomes of LAC patients was lower than that of healthy controls. Meanwhile, the expression of exosomal miR-195-5p from normal bronchial epithelial cell line BEAS-2B cells was significantly higher than that of lung cancer cell lines. The exosome labeling assay confirmed that BEAS-2B cells-derived exosomes could be captured by lung cancer cells. Furthermore, exosomal miR-195-5p derived from BEAS-2B cells remarkably inhibited the proliferation, migration, invasion of lung cancer cells, and tumor growth in vivo. In addition, exosomal miR-195-5p from BEAS-2B cells also suppressed the tube-forming ability of vascular endothelial cells. Moreover, we verified that miR-195-5p decreased apelin (APLN) expression to inactivate the Wnt signaling pathway, thereby inhibiting tumor invasiveness and angiogenesis. In conclusion, our research shows that exosomal miR-195-5p from normal bronchial epithelial cells hinders the progression of LAC, suggesting that regulation of exosomal miR-195-5p provides a novel strategy for LAC treatment.

M2 macrophage-derived exosomal miR-1911-5p promotes cell migration and invasion in lung adenocarcinoma by down-regulating CELF2 -activated ZBTB4 expression

Lung adenocarcinoma (LUAD) is one of the most aggressive, lethal cancers, comprising around 40% of lung cancer cases. Metastases are the primary cause of LUAD deaths. The mechanism underlying metastatic LUAD and tumor microenvironment remain largely unknown. To explore the effect of M2 macrophage-derived exosomes on LUAD progression. Quantitative-PCR (q-PCR) and western blot were used to measure the expression of RNAs and proteins separately. Co-culture experiments wound healing and Transwell invasion assays were performed to evaluate the effect of M2 macrophage-derived exosomes on LUAD cell migration and invasion. RNA pulldown and luciferase reporter, RNA-binding immunoprecipitation (RIP), and mRNA stability assays were conducted to explore the downstream mechanism of exosomal microRNA-1911-5p (miR-1911-5p). M2 macrophage-derived exosomes accelerated the migration and invasion of LUAD cells. M2 macrophages-secreted exosomal miR-1911-5p enhanced cell migration and invasion in LUAD. Mechanically, miR-1911-5p targeted CUGBP- and ETR-3-like family 2 (CELF2) to downregulate zinc finger and BTB domain containing 4 (ZBTB4) in LUAD. Additionally, miR-1911-5p promoted LUAD progression via ZBTB4. The present study demonstrated that M2 macrophage-derived exosomal miR-1911-5p facilitates the migration and invasion of LUAD cells by inhibiting CELF2-activated ZBTB4, which might offer insight into LUAD treatment.

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.

Crosstalk of Exosomal Non-Coding RNAs in The Tumor Microenvironment: Novel Frontiers

The tumor microenvironment (TME) is defined as a complex and dynamic tissue entity composed of endothelial, stromal, immune cells, and the blood system. The homeostasis and evolution of the TME are governed by intimate interactions among cellular compartments. The malignant behavior of cancer cells, such as infiltrating growth, proliferation, invasion, and metastasis, is predominantly dependent on the bidirectional communication between tumor cells and the TME. And such dialogue mainly involves the transfer of multifunctional regulatory molecules from tumor cells and/or stromal cells within the TME. Interestingly, increasing evidence has confirmed that exosomes carrying regulatory molecules, proteins, and nucleic acids act as an active link in cellular crosstalk in the TME. Notably, extensive studies have identified non-coding RNAs (ncRNAs), including long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), that could be encapsulated by exosomes, which regulate the coordinated function within the TME and thus participate in cancer development and progression. In this review, we summarize recent literature around the topic of the functions and mechanisms of exosomal ncRNAs in the TME and highlight their clinical significance.

Characterization of Cell Cycle-Related Competing Endogenous RNAs Using Robust Rank Aggregation as Prognostic Biomarker in Lung Adenocarcinoma

Lung adenocarcinoma (LUAD), one of the most common pathological subtypes in lung cancer, has been of concern because it is the leading cause of cancer-related deaths. Due to its poor prognosis, to identify a prognostic biomarker, this study performed an integrative analysis to screen curial RNAs and discuss their cross-talks. The messenger RNA (mRNA) profiles were primarily screened using robust rank aggregation (RRA) through several datasets, and these deregulated genes showed important roles in multiple biological pathways, especially for cell cycle and oocyte meiosis. Then, 31 candidate genes were obtained via integrating 12 algorithms, and 16 hub genes (containing homologous genes) were further screened according to the potential prognostic values. These hub genes were used to search their regulators and biological-related microRNAs (miRNAs). In this way, 10 miRNAs were identified as candidate small RNAs associated with LUAD, and then miRNA-related long non-coding RNAs (lncRNAs) were further obtained. In-depth analysis showed that 4 hub mRNAs, 2 miRNAs, and 2 lncRNAs were potential crucial RNAs in the occurrence and development of cancer, and a competing endogenous RNA (ceRNA) network was then constructed. Finally, we identified CCNA2/MKI67/KIF11:miR-30a-5p:VPS9D1-AS1 axis-related cell cycle as a prognostic biomarker, which provided RNA cross-talks among mRNAs and non-coding RNAs (ncRNAs), especially at the multiple isomiR levels that further complicated the coding–non-coding RNA regulatory network. Our findings provide insight into complex cross-talks among diverse RNAs particularly involved in isomiRs, which will enrich our understanding of mRNA–ncRNA interactions in coding–non-coding RNA regulatory networks and their roles in tumorigenesis.

Anti-Cancer Role and Therapeutic Potential of Extracellular Vesicles

Cell-cell communication is an important mechanism in biological processes. Extracellular vesicles (EVs), also referred to as exosomes, microvesicles, and prostasomes, are microvesicles secreted by a variety of cells. EVs are nanometer-scale vesicles composed of a lipid bilayer and contain biological functional molecules, such as microRNAs (miRNAs), mRNAs, and proteins. In this review, "EVs" is used as a comprehensive term for vesicles that are secreted from cells. EV research has been developing over the last four decades. Many studies have suggested that EVs play a crucial role in cell-cell communication. Importantly, EVs contribute to cancer malignancy mechanisms such as carcinogenesis, proliferation, angiogenesis, metastasis, and escape from the immune system. EVs derived from cancer cells and their microenvironments are diverse, change in nature depending on the condition. As EVs are thought to be secreted into body fluids, they have the potential to serve as diagnostic markers for liquid biopsy. In addition, cells can encapsulate functional molecules in EVs. Hence, the characteristics of EVs make them suitable for use in drug delivery systems and novel cancer treatments. In this review, the potential of EVs as anti-cancer therapeutics is discussed.