Loss of XIST in Breast Cancer Activates MSN-c-Met and Reprograms Microglia via Exosomal miRNA to Promote Brain Metastasis

Exosomal long non-coding RNAs in cancer: Interplay, modulation, and therapeutic avenues

In the intricate field of cancer biology, researchers are increasingly intrigued by the emerging role of exosomal long non-coding RNAs (lncRNAs) due to their multifaceted interactions, complex modulation mechanisms, and potential therapeutic applications. These exosomal lncRNAs, carried within extracellular vesicles, play a vital partin tumorigenesis and disease progression by facilitating communication networks between tumor cells and their local microenvironment, making them an ideal candidates for use in a liquid biopsy approach. However, exosomal lncRNAs remain an understudied area, especially in cancer biology. Therefore this review aims to comprehensively explore the dynamic interplay between exosomal lncRNAs and various cellular components, including interactions with tumor-stroma, immune modulation, and drug resistance mechanisms. Understanding the regulatory functions of exosomal lncRNAs in these processes can potentially unveil novel diagnostic markers and therapeutic targets for cancer. Additionally, the emergence of RNA-based therapeutics presents exciting opportunities for targeting exosomal lncRNAs, offering innovative strategies to combat cancer progression and improve treatment outcomes. Thus, this review provides insights into the current understanding of exosomal lncRNAs in cancer biology, highlighting their crucial roles, regulatory mechanisms, and the evolving landscape of therapeutic interventions. Furthermore, we have also discussed the advantage of exosomes as therapeutic carriers of lncRNAs for the development of personalized targeted therapy for cancer patients.

Natural products with anti-tumorigenesis potential targeting macrophage

BACKGROUND

Inflammation is a risk factor for tumorigenesis. Macrophage, a subset of immune cells with high plasticity, plays a multifaceted role in this process. Natural products, which are bioactive compounds derived from traditional herbs or foods, have exhibited diverse effects on macrophages and tumorigenesis making them a valuable resource of drug discovery or optimization in tumor prevention.

PURPOSE

Provide a comprehensive overview of the various roles of macrophages in tumorigenesis, as well as the effects of natural products on tumorigenesis by modulating macrophage function.

METHODS

A thorough literature search spanning the past two decades was carried out using PubMed, Web of Science, Elsevier, and CNKI following the PRISMA guidelines. The search terms employed included "macrophage and tumorigenesis", "natural products, macrophages and tumorigenesis", "traditional Chinese medicine and tumorigenesis", "natural products and macrophage polarization", "macrophage and tumor related microenvironment", "macrophage and tumor signal pathway", "toxicity of natural products" and combinations thereof. Furthermore, certain articles are identified through the tracking of citations from other publications or by accessing the websites of relevant journals. Studies that meet the following criteria are excluded: (1) Articles not written in English or Chinese; (2) Full texts were not available; (3) Duplicate articles and irrelevant studies. The data collected was organized and summarized based on molecular mechanisms or compound structure.

RESULTS

This review elucidates the multifaceted effect of macrophages on tumorigenesis, encompassing process such as inflammation, angiogenesis, and tumor cell invasion by regulating metabolism, non-coding RNA, signal transduction and intercellular crosstalk. Natural products, including vitexin, ovatodiolide, ligustilide, and emodin, as well as herbal remedies, have demonstrated efficacy in modulating macrophage function, thereby attenuating tumorigenesis. These interventions mainly focus on mitigating the initial inflammatory response or modifying the inflammatory environment within the precancerous niche.

CONCLUSIONS

These mechanistic insights of macrophages in tumorigenesis offer valuable ideas for researchers. The identified natural products facilitate the selection of promising candidates for future cancer drug development.

Nerve growth factor inducible (VGF) is a secreted mediator for metastatic breast cancer tropism to the brain

Brain metastases are one of the most serious clinical problems in breast cancer (BC) progression, associated with lower survival rates and a lack of effective therapies. Thus, to dissect the early stages of the brain metastatic process, we studied the impact of brain organotropic BC cells' secretomes on the establishment of the brain pre-metastatic niche (PMN). We found that BC cells with specific tropism to the brain caused significant blood-brain barrier (BBB) disruption, as well as microglial activation, in both in vitro and in vivo models. Further, we searched for a brain-organotropic metastatic signature, as a promising source for the discovery of new biomarkers involved in brain metastatic progression. Of relevance, we identified VGF (nerve growth factor inducible) as a key mediator in this process, also impacting the BBB and microglial functions both in vitro and in vivo. In a series of human breast tumors, VGF was found to be expressed in both cancer cells and the adjacent stroma. Importantly, VGF-positive tumors showed a significantly worse prognosis and were associated with HER2 (human epidermal growth factor receptor 2) overexpression and triple-negative molecular signatures. Further clinical validation in primary tumors from metastatic BC cases showed a significant association between VGF and the brain metastatic location, clearly and significantly impacting on the prognosis of BC patients with brain metastasis. In conclusion, our study reveals a unique secretome signature for BC with a tropism for the brain, highlighting VGF as a crucial mediator in this process. Furthermore, its specific impact as a poor prognostic predictor for BC patients with brain metastasis opens new avenues to target VGF to control the progression of brain metastatic disease. © 2024 The Pathological Society of Great Britain and Ireland.

Exosomes-based immunotherapy for cancer: Effective components in the naïve and engineered forms

Today, cancer treatment is one of the main challenges for researchers. The main cause of tumor cell formation is mutations that lead to uncontrolled proliferation and inhibition of apoptosis in malignant cells. Tumor cells also create a microenvironment that can suppress the immune system cells' responses through various methods, including producing soluble factors and cell-to-cell communication. After being produced from tumor cells, exosomes can also affect the functions of other cells in this microenvironment. Various studies have shown that exosomes from different sources, including tumor cells and immune cells, can be used to treat cancers due to their characteristics. Since tumor cells are rich sources of various types of tumor peptides, they can induce anti-tumor responses. Immune cells also produce exosomes that mimic the functions of their cells of origin, such that exosomes derived from NK cells and CTLs can directly lead to their apoptosis after merging with tumor cells. However, many researchers have pointed out that naïve exosomes have a limited therapeutic function, and their therapeutic potential can be increased by manipulating and engineering them. There are various methods to modify exosomes and improve their therapeutic potential. In general, these methods are divided into two parts, which include changing the cell of origin of the exosome and encapsulating the exosome to carry different drugs. In this review, we will discuss the studies on the therapeutic use of naive and engineered exosomes and provide an update on new studies in this field.

Long noncoding RNA XIST: a novel independent prognostic biomarker for patients with ABC-DLBCL receiving R-CHOP treatment

Approximately one-third of activated B-cell-like diffuse large B-cell lymphoma (ABC-DLBCL) cases were unresponsive to standard first-line therapy; thus, identifying biomarkers to evaluate therapeutic efficacy and assessing the emergence of drug resistance is crucial. Through early-stage screening, long noncoding RNA (lncRNA) X-inactive specific transcript (XIST) was found to be correlated with the R-CHOP treatment response. This study aimed to clarify the characteristics of XIST in ABC-DLBCL. The expression level of XIST in 161 patients with ABC-DLBCL receiving R-CHOP therapy was examined via RNA in situ hybridization, and the association between XIST expression and clinicopathological features, treatment response and prognosis was analyzed in the study cohort and validated in the Gene Expression Omnibus cohort. Cell biological experiments and bioinformatics analyses were conducted to reveal aberrant signaling. The proportion of complete response in patients with high XIST expression was lower than that in patients with low XIST expression (53.8% versus 77.1%) (P = 0.002). High XIST expression was remarkably associated with the characteristics of tumor progression and was an independent prognostic element for overall survival (P = 0.039) and progression-free survival (P = 0.027) in ABC-DLBCL. XIST was proven to be involved in m6A-related methylation and ATF6-associated autophagy. XIST knockdown repressed ABC-DLBCL cellular proliferation by regulating Raf/MEK/ERK signaling. High XIST expression was associated with ABC-DLBCL tumorigenesis and development and contributed to R-CHOP treatment resistance. XIST may be a promising signal to predict ABC-DLBCL prognosis.

An emerging link between lncRNAs and cancer sex dimorphism

The prevalence and progression of cancer differ in males and females, and thus, sexual dimorphism in tumor development directly impacts clinical research and medicine. Long non-coding RNAs (lncRNAs) are increasingly recognized as important players in gene expression and various cellular processes, including cancer development and progression. In recent years, lncRNAs have been implicated in the differences observed in cancer incidence, progression, and treatment responses between men and women. Here, we present a brief overview of the current knowledge regarding the role of lncRNAs in cancer sex dimorphism, focusing on how they affect epigenetic processes in male and female mammalian cells. We discuss the potential mechanisms by which lncRNAs may contribute to sex differences in cancer, including transcriptional control of sex chromosomes, hormonal signaling pathways, and immune responses. We also propose strategies for studying lncRNA functions in cancer sex dimorphism. Furthermore, we emphasize the importance of considering sex as a biological variable in cancer research and the need to investigate the role lncRNAs play in mediating these sex differences. In summary, we highlight the emerging link between lncRNAs and cancer sex dimorphism and their potential as therapeutic targets.

LncRNAs act as modulators of macrophages within the tumor microenvironment

Long non-coding RNAs (lncRNAs) have been established as pivotal players in various cellular processes, encompassing the regulation of transcription, translation and post-translational modulation of proteins, thereby influencing cellular functions. Notably, lncRNAs exert a regulatory influence on diverse biological processes, particularly in the context of tumor development. Tumor-associated macrophages (TAMs) exhibit the M2 phenotype, exerting significant impact on crucial processes such as tumor initiation, angiogenesis, metastasis and immune evasion. Elevated infiltration of TAMs into the tumor microenvironment (TME) is closely associated with a poor prognosis in various cancers. LncRNAs within TAMs play a direct role in regulating cellular processes. Functioning as integral components of tumor-derived exosomes, lncRNAs prompt the M2-like polarization of macrophages. Concurrently, reports indicate that lncRNAs in tumor cells contribute to the expression and release of molecules that modulate TAMs within the TME. These actions of lncRNAs induce the recruitment, infiltration and M2 polarization of TAMs, thereby providing critical support for tumor development. In this review, we survey recent studies elucidating the impact of lncRNAs on macrophage recruitment, polarization and function across different types of cancers.

Targeting the HSP47-collagen axis inhibits brain metastasis by reversing M2 microglial polarization and restoring anti-tumor immunity

Brain metastases (BrMs) are the leading cause of death in patients with solid cancers. BrMs exhibit a highly immunosuppressive milieu and poor response to immunotherapies; however, the underlying mechanism remains largely unclear. Here, we show that upregulation of HSP47 in tumor cells drives metastatic colonization and outgrowth in the brain by creating an immunosuppressive microenvironment. HSP47-mediated collagen deposition in the metastatic niche promotes microglial polarization to the M2 phenotype via the α2β1 integrin/nuclear factor κB pathway, which upregulates the anti-inflammatory cytokines and represses CD8+ T cell anti-tumor responses. Depletion of microglia reverses HSP47-induced inactivation of CD8+ T cells and abolishes BrM. Col003, an inhibitor disrupting HSP47-collagen association restores an anti-tumor immunity and enhances the efficacy of anti-PD-L1 immunotherapy in BrM-bearing mice. Our study supports that HSP47 is a critical determinant of M2 microglial polarization and immunosuppression and that blocking the HSP47-collagen axis represents a promising therapeutic strategy against brain metastatic tumors.

Unlocking c-MET: A comprehensive journey into targeted therapies for breast cancer

Breast cancer is the most common malignancy among women, posing a formidable health challenge worldwide. In this complex landscape, the c-MET (cellular-mesenchymal epithelial transition factor) receptor tyrosine kinase (RTK), also recognized as the hepatocyte growth factor (HGF) receptor (HGFR), emerges as a prominent protagonist, displaying overexpression in nearly 50% of breast cancer cases. Activation of c-MET by its ligand, HGF, secreted by neighboring mesenchymal cells, contributes to a cascade of tumorigenic processes, including cell proliferation, metastasis, angiogenesis, and immunosuppression. While c-MET inhibitors such as crizotinib, capmatinib, tepotinib and cabozantinib have garnered FDA approval for non-small cell lung cancer (NSCLC), their potential within breast cancer therapy is still undetermined. This comprehensive review embarks on a journey through structural biology, multifaceted functions, and intricate signaling pathways orchestrated by c-MET across cancer types. Furthermore, we highlight the pivotal role of c-MET-targeted therapies in breast cancer, offering a clinical perspective on this promising avenue of intervention. In this pursuit, we strive to unravel the potential of c-MET as a beacon of hope in the fight against breast cancer, unveiling new horizons for therapeutic innovation.

Long Non-coding RNA X-Inactive Specific Transcript Promotes Esophageal Squamous Cell Carcinoma Progression via the MicroRNA 34a/Zinc Finger E-box-Binding Homeobox 1 Pathway

BACKGROUND

The long non-coding RNA X-inactive specific transcript (XIST) plays a crucial role in transcriptional silencing of the X chromosome. Zinc finger E-box-binding homeobox 1 (ZEB1) is a transcription factor involved in epithelial-mesenchymal transition (EMT) regulation.

AIMS

This study aimed to investigate the impact of XIST on esophageal squamous cell carcinoma (ESCC) progression and its underlying mechanism involving the miR-34a/ZEB1/E-cadherin/EMT pathway.

METHODS

XIST and ZEB1 expression were analyzed using quantitative PCR and immunohistochemistry. XIST knockdown was achieved in KYSE150 ESCC cells using siRNA or shRNA lentivirus transfection. Proliferation, migration, and invasion abilities were assessed, and luciferase reporter assays were performed to confirm XIST-miR-34a-ZEB1 interactions. In vivo ESCC growth was evaluated using a xenograft mouse model.

RESULTS

XIST and ZEB1 were upregulated in tumor tissues, correlating with metastasis and reduced survival. XIST knockdown inhibited proliferation, migration, and invasion of KYSE150 cells. It decreased ZEB1 expression, increased E-cadherin and miR-34a levels. Luciferase reporter assays confirmed miR-34a binding to XIST and ZEB1. XIST knockdown suppressed xenograft tumor growth.

CONCLUSION

XIST promotes ESCC progression via the miR-34a/ZEB1/E-cadherin/EMT pathway. Targeting the XIST/miR-34a/ZEB1 axis holds therapeutic potential and serves as a prognostic biomarker in ESCC.

Extracellular vesicle-mediated pre-metastatic niche formation via altering host microenvironments

The disordered growth, invasion and metastasis of cancer are mainly attributed to bidirectional cell-cell interactions. Extracellular vesicles (EVs) secreted by cancer cells are involved in orchestrating the formation of pre-metastatic niches (PMNs). Tumor-derived EVs mediate bidirectional communication between tumor and stromal cells in local and distant microenvironments. EVs carrying mRNAs, small RNAs, microRNAs, DNA fragments, proteins and metabolites determine metastatic organotropism, enhance angiogenesis, modulate stroma cell phenotypes, restructure the extracellular matrix, induce immunosuppression and modify the metabolic environment of organs. Evidence indicates that EVs educate stromal cells in secondary sites to establish metastasis-supportive microenvironments for seeding tumor cells. In this review, we provide a comprehensive overview of PMN formation and the underlying mechanisms mediated by EVs. Potential approaches to inhibit cancer metastasis by inhibiting the formation of PMNs are also presented.

The Role of Microglia in Brain Metastases: Mechanisms and Strategies

Brain metastases and related complications are one of the major fatal factors in cancer. Patients with breast cancer, lung cancer, and melanoma are at a high risk of developing brain metastases. However, the mechanisms underlying the brain metastatic cascade remain poorly understood. Microglia, one of the major resident macrophages in the brain parenchyma, are involved in multiple processes associated with brain metastasis, including inflammation, angiogenesis, and immune modulation. They also closely interact with metastatic cancer cells, astrocytes, and other immune cells. Current therapeutic approaches against metastatic brain cancers, including small-molecule drugs, antibody-coupled drugs (ADCs), and immune-checkpoint inhibitors (ICIs), have compromised efficacy owing to the impermeability of the blood-brain barrier (BBB) and complex brain microenvironment. Targeting microglia is one of the strategies for treating metastatic brain cancer. In this review, we summarize the multifaceted roles of microglia in brain metastases and highlight them as potential targets for future therapeutic interventions.

Nanomaterials for brain metastasis

Tumor metastasis is a significant contributor to the mortality of cancer patients. Specifically, current conventional treatments are unable to achieve complete remission of brain metastasis. This is due to the unique pathological environment of brain metastasis, which differs significantly from peripheral metastasis. Brain metastasis is characterized by high tumor mutation rates and a complex microenvironment with immunosuppression. Additionally, the presence of blood-brain barrier (BBB)/blood tumor barrier (BTB) restricts drug leakage into the brain. Therefore, it is crucial to take account of the specific characteristics of brain metastasis when developing new therapeutic strategies. Nanomaterials offer promising opportunities for targeted therapies in treating brain metastasis. They can be tailored and customized based on specific pathological features and incorporate various treatment approaches, which makes them advantageous in advancing therapeutic strategies for brain metastasis. This review provides an overview of current clinical treatment options for patients with brain metastasis. It also explores the roles and changes that different cells within the complex microenvironment play during tumor spread. Furthermore, it highlights the use of nanomaterials in current brain treatment approaches.

The role of microRNAs in brain metastasis

Brain metastasis (BM) is the most common type of brain tumor and frequently foreshadows disease progression and poor overall survival with patients having a median survival of 6 months. 70,000 new cases of BM are diagnosed each year in the United States (US) and the incidence rate for BM is increasing with improved detection. MicroRNAs (miRNAs) are small non-coding RNAs that serve as critical regulators of gene expression and can act as powerful oncogenes and tumor suppressors. MiRNAs have been heavily implicated in cancer and proposed as biomarkers or therapeutic targets or agents. In this review, we summarize an extensive body of scientific work investigating the role of microRNAs in BM. We discuss miRNA dysregulation, functions, targets, and mechanisms of action in BM and present the current standing of miRNAs as biomarkers and potential therapeutics for BM. We conclude with future directions of miRNA basic and clinical research in BM.

Radiotherapy in Preclinical Models of Brain Metastases: A Review and Recommendations for Future Studies

Brain metastases (BMs) frequently occur in primary tumors such as lung cancer, breast cancer, and melanoma, and are associated with notably short natural survival. In addition to surgical interventions, chemotherapy, targeted therapy, and immunotherapy, radiotherapy (RT) is a crucial treatment for BM and encompasses whole-brain radiotherapy (WBRT) and stereotactic radiosurgery (SRS). Validating the efficacy and safety of treatment regimens through preclinical models is imperative for successful translation to clinical application. This not only advances fundamental research but also forms the theoretical foundation for clinical study. This review, grounded in animal models of brain metastases (AM-BM), explores the theoretical underpinnings and practical applications of radiotherapy in combination with chemotherapy, targeted therapy, immunotherapy, and emerging technologies such as nanomaterials and oxygen-containing microbubbles. Initially, we provided a concise overview of the establishment of AM-BMs. Subsequently, we summarize key RT parameters (RT mode, dose, fraction, dose rate) and their corresponding effects in AM-BMs. Finally, we present a comprehensive analysis of the current research status and future directions for combination therapy based on RT. In summary, there is presently no standardized regimen for AM-BM treatment involving RT. Further research is essential to deepen our understanding of the relationships between various parameters and their respective effects.

Harnessing immunotherapy for brain metastases: insights into tumor-brain microenvironment interactions and emerging treatment modalities

Brain metastases signify a deleterious milestone in the progression of several advanced cancers, predominantly originating from lung, breast and melanoma malignancies, with a median survival timeframe nearing six months. Existing therapeutic regimens yield suboptimal outcomes; however, burgeoning insights into the tumor microenvironment, particularly the immunosuppressive milieu engendered by tumor-brain interplay, posit immunotherapy as a promising avenue for ameliorating brain metastases. In this review, we meticulously delineate the research advancements concerning the microenvironment of brain metastases, striving to elucidate the panorama of their onset and evolution. We encapsulate three emergent immunotherapeutic strategies, namely immune checkpoint inhibition, chimeric antigen receptor (CAR) T cell transplantation and glial cell-targeted immunoenhancement. We underscore the imperative of aligning immunotherapy development with in-depth understanding of the tumor microenvironment and engendering innovative delivery platforms. Moreover, the integration with established or avant-garde physical methodologies and localized applications warrants consideration in the prevailing therapeutic schema.

A novel risk signature for predicting brain metastasis in patients with lung adenocarcinoma

BACKGROUND

Brain metastasis (BM) are a devastating consequence of lung cancer. This study was aimed to screen risk factors for predicting BM.

METHODS

Using an in vivo BM preclinical model, we established a series of lung adenocarcinoma (LUAD) cell subpopulations with different metastatic ability. Quantitative proteomics analysis was used to screen and identify the differential protein expressing map among subpopulation cells. Q-PCR and Western-blot were used to validate the differential proteins in vitro. The candidate proteins were measured in LUAD tissue samples (n = 81) and validated in an independent TMA cohort (n = 64). A nomogram establishment was undertaken by performing multivariate logistic regression analysis.

RESULTS

The quantitative proteomics analysis, qPCR and Western blot assay implied a five-gene signature that might be key proteins associated with BM. In multivariate analysis, the occurrence of BM was associated with age ≤ 65 years, high expressions of NES and ALDH6A1. The nomogram showed an area under the receiver operating characteristic curve (AUC) of 0.934 (95% CI, 0.881-0.988) in the training set. The validation set showed a good discrimination with an AUC of 0.719 (95% CI, 0.595-0.843).

CONCLUSIONS

We have established a tool that is able to predict occurrence of BM in LUAD patients. Our model based on both clinical information and protein biomarkers will help to screen patient in high-risk population of BM, so as to facilitate preventive intervention in this part of the population.

Extracellular vesicles in the breast cancer brain metastasis: physiological functions and clinical applications

Breast cancer, which exhibits an increasing incidence and high mortality rate among cancers, is predominantly attributed to metastatic malignancies. Brain metastasis, in particular, significantly contributes to the elevated mortality in breast cancer patients. Extracellular vesicles (EVs) are small lipid bilayer vesicles secreted by various cells that contain biomolecules such as nucleic acids and proteins. They deliver these bioactive molecules to recipient cells, thereby regulating signal transduction and protein expression levels. The relationship between breast cancer metastasis and EVs has been extensively investigated. In this review, we focus on the molecular mechanisms by which EVs promote brain metastasis in breast cancer. Additionally, we discuss the potential of EV-associated molecules as therapeutic targets and their relevance as early diagnostic markers for breast cancer brain metastasis.

The role of extracellular vesicles in circulating tumor cell-mediated distant metastasis

Current research has demonstrated that extracellular vesicles (EVs) and circulating tumor cells (CTCs) are very closely related in the process of distant tumor metastasis. Primary tumors are shed and released into the bloodstream to form CTCs that are referred to as seeds to colonize and grow in soil-like distant target organs, while EVs of tumor and nontumor origin act as fertilizers in the process of tumor metastasis. There is no previous text that provides a comprehensive review of the role of EVs on CTCs during tumor metastasis. In this paper, we reviewed the mechanisms of EVs on CTCs during tumor metastasis, including the ability of EVs to enhance the shedding of CTCs, protect CTCs in circulation and determine the direction of CTC metastasis, thus affecting the distant metastasis of tumors.

Therapeutic strategies for HER2-positive breast cancer with central nervous system involvement: a literature review and future perspectives

Background and Objective

Brain metastases (BMs) are present in approximately 55% of patients with HER2-positive breast cancer (HER2+ BC). The introduction of anti-HER2 agents has radically changed the prognosis of these patients by prolonging overall survival.

Methods

In this review, we describe the biology of central nervous system (CNS) spreading in patients with HER2+ BC. We also provide a literature review of current treatment strategies of brain metastatic BC, focusing on HER2+ disease, and future perspectives.

Key Content and Findings

Treatment of symptomatic BMs includes traditionally neurosurgery and/or radiotherapy, depending on the number of metastases, performance status and systemic disease control. Local treatments, such as surgical excision of BM and stereotactic radiosurgery (SRS), when feasible, are preferred over whole-brain radiotherapy, because of related cognitive impairment. These treatments can lead to a local control of the disease, however, systemic relapses can affect the prognosis of these patients. Recently, new anti-HER2 agents have demonstrated to be effective on BMs, thereby leading to improved survival outcomes with an acceptable quality of life. Despite the clinical benefit of these approaches, BMs still represent a cause of death and effective therapeutic strategies are needed.

Conclusions

Different targeted agents have demonstrated significant efficacy with tolerable safety profiles in HER2+ BC patients with BM, and have already been approved for clinical use in this setting. A better understanding of the molecular mechanisms underlying the onset of BMs could suggest novel targeted approaches in order to prevent CNS localization or delay progression to CNS in HER-2 metastatic patients.

m6A modified BACE1-AS contributes to liver metastasis and stemness-like properties in colorectal cancer through TUFT1 dependent activation of Wnt signaling

BACKGROUND

Liver metastasis is one of the most important reasons for high mortality of colorectal cancer (CRC). Growing evidence illustrates that lncRNAs play a critical role in CRC liver metastasis. Here we described a novel function and mechanisms of BACE1-AS promoting CRC liver metastasis.

METHODS

qRT-PCR and in situ hybridization were performed to examine the BACE1-AS level in CRC. IGF2BP2 binding to m6A motifs in BACE1-AS was determined by RIP assay and S1m-tagged immunoprecipitation. Transwell assay and liver metastasis mice model experiments were performed to examine the metastasis capabilities of BACE1-AS knockout cells. Stemness-like properties was examined by tumor sphere assay and the expression of stemness biomarkers. Microarray data were acquired to analyze the signaling pathways involved in BACE1-AS promoting CRC metastasis.

RESULTS

BACE1-AS is the most up-regulated in metastatic CRC associated with unfavorable prognosis. Sequence blast revealed two m6A motifs in BACE1-AS. IGF2BP2 binding to these two m6A motifs is required for BACE1-AS boost in metastatic CRC. m6A modified BACE1-AS drives CRC cells migration and invasion and liver metastasis both in vitro and in vivo. Moreover, BACE1-AS maintains the stemness-like properties of CRC cells. Mechanically, BACE1-AS promoted TUFT1 expression by ceRNA network through miR-214-3p. CRC patients with such ceRNA network suffer poorer prognosis than ceRNA-negative patients. Depletion of TUFT1 mimics BACE1-AS loss. BACE1-AS activated Wnt signaling pathway in a TUFT1 dependent manner. BACE1-AS/miR-214-3p/TUFT1/Wnt signaling regulatory axis is essential for CRC liver metastasis. Pharmacologic inhibition of Wnt signaling pathway repressed liver metastasis and stemness-like features in BACE1-AS over-expressed CRC cells.

CONCLUSION

Our study demonstrated BACE1-AS as a novel target of IGF2BP2 through m6A modification. m6A modified BACE1-AS promotes CRC liver metastasis through TUFT1 dependent activation of Wnt signaling pathway. Thus, targeting BACE1-AS and its downstream Wnt signaling pathways may provide a new opportunity for metastatic CRC intervention and treatment.

The Emerging Roles of Exosomal miRNAs in Breast Cancer Progression and Potential Clinical Applications

Breast cancer remains the leading malignancy in terms of morbidity and mortality today. The tumor microenvironment of breast cancer includes multiple cell types, secreted proteins, and signaling components such as exosomes. Among these, exosomes have a lipid bilayer structure. Exosomes can reflect the biological traits of the parent cell and carry a variety of biologically active components, including proteins, lipids, small molecules, and non-coding RNAs, which include miRNA, lncRNA, and circRNA. MiRNAs are a group of non-coding RNAs of approximately 20-23 nucleotides in length encoded by the genome, triggering silencing and functional repression of target genes. MiRNAs have been shown to play a significant role in the development of cancer owing to their role in the prognosis, pathogenesis, diagnosis, and treatment of cancer. MiRNAs in exosomes can serve as effective mediators of information transfer from parental cells to recipient cells and trigger changes in biological traits such as proliferation, invasion, migration, and drug resistance. These changes can profoundly alter the progression of breast cancer. Therefore, here, we systematically summarize the association of exosomal miRNAs on breast cancer progression, diagnosis, and treatment in the hope of providing novel strategies and directions for subsequent breast cancer treatment.

Exosomal circRNA RHOT1 promotes breast cancer progression by targeting miR-204-5p/ PRMT5 axis

BACKGROUND

Circular RNA RHOT1 (circRHOT1) plays crucial roles in tumorigenesis by competing with microRNAs. It is largely abundant in tumor cell-derived exosomes. Meanwhile, cancer-derived exosomes participate in diverse biological processes. However, the expression patterns and functions of exosomal circRHOT1 in breast cancer remain unknown. This study is aimed to investigate and elucidate the exosomal circRHOT1/miR-204-5p/PRMT5 axis in breast cancer.

METHODS

The exosomes derived from serum samples of breast cancer patients and breast cancer cell lines were characterized using transmission electron microscopy and Western blot. MTT, colony formation, wound healing, and transwell assays were utilized to analyze cell proliferation, migration, and invasion of breast cancer cells. Flow cytometry was used for apoptosis analysis. The bioinformatics method was employed to screen differentially expressed novel circRNAs and predict the microRNA targets of circRHOT1. Dual-luciferase reporter gene assays were performed to verify their direct interaction. Finally, Xenograft experiments were used to investigate the effect of exosomal circRHOT1 on tumor growth in vivo.

RESULTS

CircRHOT1 exhibited significantly high expression in exosomes derived from the serum of breast cancer patients and breast cancer cell lines, which suggested its potential diagnostic value. Breast cancer-derived exosomes promoted the cell proliferation, migration, invasion, and epithelial-mesenchymal transition of breast cancer cells while inhibiting apoptosis. However, exosomes with downregulated circRHOT1 inhibited the growth of co-cultured cells. Mechanistically, circRHOT1 acted as a sponge of miR-204-5p and promoted protein arginine methyltransferase 5 (PRMT5) expression. Moreover, miR-204-5p inhibitor and pcPRMT5 could reverse the tumor suppressive effects mediated by circRHOT1-knockdown. Furthermore, treatment with exosomes derived from breast cancer cells with circRHOT1 knockdown attenuated tumor growth in tumor-bearing nude mice, which was accompanied by a reduction in PRMT5 expression and an enhancement of miR-204-5p expression.

CONCLUSION

The exosomal circRHOT1 may promote breast cancer progression by regulating the miR-204-5p/PRMT5 axis. The current study strengthens the role of circRHOT1, miR-204-5p, and PRMT5 in breast cancer development and provides a potential treatment strategy for breast cancer.

Mechanisms of Organ-Specific Metastasis of Breast Cancer

Cancer metastasis, or the development of secondary tumors in distant tissues, accounts for the vast majority of fatalities in patients with breast cancer. Breast cancer cells show a striking proclivity to metastasize to distinct organs, specifically the lung, liver, bone, and brain, where they face unique environmental pressures and a wide variety of tissue-resident cells that together create a strong barrier for tumor survival and growth. As a consequence, successful metastatic colonization is critically dependent on reciprocal cross talk between cancer cells and host cells within the target organ, a relationship that shapes the formation of a tumor-supportive microenvironment. Here, we discuss the mechanisms governing organ-specific metastasis in breast cancer, focusing on the intricate interactions between metastatic cells and specific niche cells within a secondary organ, and the remarkable adaptations of both compartments that cooperatively support cancer growth. More broadly, we aim to provide a framework for the microenvironmental prerequisites within each distinct metastatic site for successful breast cancer metastatic seeding and outgrowth.

Integrative Analysis Revealed LINC00847 as a Potential Target of Tumor Immunotherapy

Lung cancer is the second most commonly diagnosed cancer and the leading cause of cancer-related death. Lung adenocarcinoma (LUAD) is the most common form of lung cancer and has a low 5-year survival rate. Therefore, much more research is needed to identify cancer biomarkers, promote biomarker-driven therapy and improve treatment outcomes. LncRNAs have been reported to participate in various physiological and pathological processes, especially in cancer, and thus have attracted much attention. In this study, lncRNAs were screened from the single-cell RNA-seq dataset CancerSEA. Among them, four lncRNAs (HCG18, NNT-AS1 and LINC00847 and CYTOR) were closely associated with the prognosis of LUAD patients according to Kaplan-Meier analysis. Further study explored the correlations between these four lncRNAs and immune cell infiltration in cancer. In LUAD, LINC00847 was positively correlated with the immune infiltration of B cells, CD8 T cells, and dendritic cells. LINC00847 decreased the expression of PD-L1, immune checkpoint blockade (ICB) immunotherapy-related gene, which suggests that LINC00847 is a potential new target for tumor immunotherapy.

Revolutionizing treatment for triple-negative breast cancer: Harnessing the power of exosomal miRNAs for targeted therapy

Triple-negative breast cancer (TNBC) represents a challenging and aggressive form of breast cancer associated with limited treatment options and poor prognosis. Although chemotherapy is a primary therapeutic approach, drug resistance often hinders treatment success. However, the expanding knowledge of TNBC subtypes and molecular biology has paved the way for targeted therapies. Notably, exosomes (extracellular vesicles) have emerged as crucial carriers of tumorigenic factors involved in oncogenesis and drug resistance, facilitating cell-to-cell communication and offering potential as self-delivery systems. Among the cargo carried by exosomes, microRNAs (miRNAs) have gained attention due to their ability to mediate epigenetic changes in recipient cells upon transfer. Research has confirmed dysregulation of exosomal miRNAs in breast cancer cells compared to healthy cells, establishing them as promising biomarkers for cancer diagnosis and prognosis. In this comprehensive review, we summarize the latest research findings that underscore the diagnostic and prognostic significance of exosomal miRNAs in TNBC treatment. Furthermore, we explore contemporary therapeutic approaches utilizing these exosomal miRNAs for the benefit of TNBC patients, shedding light on potential breakthroughs in TNBC management.

Long non-coding RNA and the tumor microenvironment: Prospects for clinical applications in breast cancer

Breast cancer has surpassed lung cancer as the number one cancer worldwide, and invasion and metastasis are still the main causes of death in breast cancer patients. The tumor microenvironment (TME) is an important site for the growth of tumor cells nourished by vascular networks, and various components of the TME interact strongly with cancer cells and are one of the important mechanisms of tumor progression and metastasis. In recent years, many studies have reported that long non-coding RNAs (LncRNAs) are involved in the formation of TME and influence the process of tumorigenesis and metastasis. This paper reviews the basic characteristics and functional roles of LncRNA in breast cancer TME and introduces the various mechanisms of LncRNA in breast cancer microenvironment that induce breast cancer development and metastasis in three directions: immune cells, non-immune cells, and extracellular matrix in TME, providing potential biomarkers or therapeutic targets for clinical practice.

The macrophage polarization by miRNAs and its potential role in the treatment of tumor and inflammation (Review)

The characteristics of monocyte/macrophage lineage are diversity and plasticity, mainly manifested by M1 and M2 subtypes in the body tissues, and playing different roles in the immunity. In the polarization process of macrophages, the classic molecular mechanism is related to sequential transcription factors. Whether in tumor or inflammatory local microenvironment, the pathological factors of the local microenvironment often affect the polarization of M1 and M2 macrophages, and participate in the occurrence and development of these pathological processes. In recent years, a growing number of research results demonstrated that non‑coding RNA (ncRNA) also participates in the polarization process of macrophages, in addition to traditional cytokines and transcriptional regulation signal pathway molecules. Among numerous ncRNAs, microRNAs (miRNAs) have attracted more attention from scholars both domestically and internationally, and significant progress has been made in basic and clinical research. Therefore, for improved understanding of the molecular mechanism of miRNAs in macrophage polarization and analysis of the potential value of this regulatory pathway in tumor and inflammatory intervention therapy, a comprehensive review of the progress of relevant literature research was conducted and some viewpoints and perspectives were proposed.

The role of non-coding RNAs in extracellular vesicles in breast cancer and their diagnostic implications

Breast Cancer (BC) is the most common form of cancer worldwide, responsible for 25% of cancers in women. Whilst treatment is effective and often curative in early BC, metastatic disease is incurable, highlighting the need for early detection. Currently, early detection relies on invasive procedures, however recent studies have shown extracellular vesicles (EVs) obtained from liquid biopsies may have clinical utility. EVs transport diverse bioactive cargos throughout the body, play major roles in intercellular communication and, importantly, mirror their cell of origin. In cancer cells, EVs alter the behaviour of the tumour microenvironment (TME), forming a bridge of communication between cancerous and non-cancerous cells to alter all aspects of cancer progression, including the formation of a pre-metastatic niche. Through gene regulatory frameworks, non-coding RNAs (ncRNAs) modulate vital molecular and cellular processes and can act as both tumour suppressors and oncogenic drivers in various cancer types. EVs transport and protect ncRNAs, facilitating their use clinically as liquid biopsies for early BC detection. This review summarises current research surrounding ncRNAs and EVs within BC, focusing on their roles in cancer progression through bi-directional communication with the microenvironment and their diagnostic implications. The role of EV ncRNAs in breast cancer. A representation of the different EV ncRNAs involved in tumourigenic processes in breast cancer. Pro-tumourigenic ncRNAs displayed in green and ncRNAs which inhibit oncogenic processes are shown in red.

Non-Coding RNA in Microglia Activation and Neuroinflammation in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by complex pathophysiological features. Amyloid plaques resulting from extracellular amyloid deposition and neurofibrillary tangles formed by intracellular hyperphosphorylated tau accumulation serve as primary neuropathological criteria for AD diagnosis. The activation of microglia has been closely associated with these pathological manifestations. Non-coding RNA (ncRNA), a versatile molecule involved in various cellular functions such as genetic information storage and transport, as well as catalysis of biochemical reactions, plays a crucial role in microglial activation. This review aims to investigate the regulatory role of ncRNAs in protein expression by directly targeting genes, proteins, and interactions. Furthermore, it explores the ability of ncRNAs to modulate inflammatory pathways, influence the expression of inflammatory factors, and regulate microglia activation, all of which contribute to neuroinflammation and AD. However, there are still significant controversies surrounding microglial activation and polarization. The categorization into M1 and M2 phenotypes may oversimplify the intricate and multifaceted regulatory processes in microglial response to neuroinflammation. Limited research has been conducted on the role of ncRNAs in regulating microglial activation and inducing distinct polarization states in the context of neuroinflammation. Moreover, the regulatory mechanisms through which ncRNAs govern microglial function continue to be refined. The current understanding of ncRNA regulatory pathways involved in microglial activation remains incomplete and may be influenced by spatial, temporal, and tissue-specific factors. Therefore, further in-depth investigations are warranted. In conclusion, there are ongoing debates and uncertainties regarding the activation and polarization of microglial cells, particularly concerning the categorization into M1 and M2 phenotypes. The study of ncRNA regulation in microglial activation and polarization, as well as its mechanisms, is still in its early stages and requires further investigation. However, this review offers new insights and opportunities for therapeutic approaches in AD. The development of ncRNA-based drugs may hold promise as a new direction in AD treatment.

The origin of brain malignancies at the blood-brain barrier

Despite improvements in extracranial therapy, survival rate for patients suffering from brain metastases remains very poor. This is coupled with the incidence of brain metastases continuing to rise. In this review, we focus on core contributions of the blood-brain barrier to the origin of brain metastases. We first provide an overview of the structure and function of the blood-brain barrier under physiological conditions. Next, we discuss the emerging idea of a pre-metastatic niche, namely that secreted factors and extracellular vesicles from a primary tumor site are able to travel through the circulation and prime the neurovasculature for metastatic invasion. We then consider the neurotropic mechanisms that circulating tumor cells possess or develop that facilitate disruption of the blood-brain barrier and survival in the brain's parenchyma. Finally, we compare and contrast brain metastases at the blood-brain barrier to the primary brain tumor, glioma, examining the process of vessel co-option that favors the survival and outgrowth of brain malignancies.

The role of lncRNAs and exosomal lncRNAs in cancer metastasis

Tumor metastasis is the main reason for cancer-related death, but there is still a lack of effective therapeutic to inhibit tumor metastasis. Therefore, the discovery and study of new tumor metastasis regulators is a prominent measure for cancer diagnosis and treatment. Long non-coding RNA (lncRNA) is a type of non-coding RNAs over 200 bp in length. It has been shown that the abnormally expressed lncRNAs promote tumor metastasis by participating in the epithelial-to-mesenchymal transition (EMT) process, altering the metastatic tumor microenvironment, or changing the extracellular matrix. It is,thus, critical to explore the regulation of lncRNAs expression in cells and the molecular mechanism of lncRNA-mediated cancer metastasis. Simultaneously, it has been shown that lncRNA is one kind of the main components of exosomes, which protects lncRNAs from being rapidly degraded. Meanwhile, the components of exosomes are parent-specific, making exosomal lncRNAs to be potential tumor metastasis markers and therapeutic targets. In view of this, we also summarized the aberrant enrichment of lncRNAs in exosomes and their role in metastatic cancer. The aberrant lncRNAs and exosomal lncRNAs gradually become biomarkers and therapeutic targets for tumor metastatic, and the potential of lncRNAs in therapeutics are studied here. Besides, the lncRNA-related databases, which could greatly facilitate in the study of lncRNAs and exosomal lncRNAs in metastatic of cancer are included in this review.

Deciphering the Functional Status of Breast Cancers through the Analysis of Their Extracellular Vesicles

Breast cancer (BC) accounts for the highest incidence of tumor-related mortality among women worldwide, justifying the growing search for molecular tools for the early diagnosis and follow-up of BC patients under treatment. Circulating extracellular vesicles (EVs) are membranous nanocompartments produced by all human cells, including tumor cells. Since minimally invasive methods collect EVs, which represent reservoirs of signals for cell communication, these particles have attracted the interest of many researchers aiming to improve BC screening and treatment. Here, we analyzed the cargoes of BC-derived EVs, both proteins and nucleic acids, which yielded a comprehensive list of potential markers divided into four distinct categories, namely, (i) modulation of aggressiveness and growth; (ii) preparation of the pre-metastatic niche; (iii) epithelial-to-mesenchymal transition; and (iv) drug resistance phenotype, further classified according to their specificity and sensitivity as vesicular BC biomarkers. We discuss the therapeutic potential of and barriers to the clinical implementation of EV-based tests, including the heterogeneity of EVs and the available technologies for analyzing their content, to present a consistent, reproducible, and affordable set of markers for further evaluation.

Identification of monotonically expressed long non-coding RNA signatures for breast cancer using variational autoencoders

As breast cancer is a multistage progression disease resulting from a genetic sequence of mutations, understanding the genes whose expression values increase or decrease monotonically across pathologic stages can provide insightful clues about how breast cancer initiates and advances. Utilizing variational autoencoder (VAE) networks in conjunction with traditional statistical testing, we successfully ascertain long non-coding RNAs (lncRNAs) that exhibit monotonically differential expression values in breast cancer. Subsequently, we validate that the identified lncRNAs really present monotonically changed patterns. The proposed procedure identified 248 monotonically decreasing expressed and 115 increasing expressed lncRNAs. They correspond to a total of 65 and 33 genes respectively, which possess unique known gene symbols. Some of them are associated with breast cancer, as suggested by previous studies. Furthermore, enriched pathways by the target mRNAs of these identified lncRNAs include the Wnt signaling pathway, human papillomavirus (HPV) infection, and Rap 1 signaling pathway, which have been shown to play crucial roles in the initiation and development of breast cancer. Additionally, we trained a VAE model using the entire dataset. To assess the effectiveness of the identified lncRNAs, a microarray dataset was employed as the test set. The results obtained from this evaluation were deemed satisfactory. In conclusion, further experimental validation of these lncRNAs with a large-sized study is warranted, and the proposed procedure is highly recommended.

A Novel Cell Membrane-Associated RNA Extraction Method and Its Application in the Discovery of Breast Cancer Markers

Cell membrane-associated RNA (mem-RNA) has been demonstrated to be cell-specific and disease-related and are considered as potential biomarkers for disease diagnostics, drug delivery, and cell screening. However, there is still a lack of methods specifically designed to extract mem-RNA from cells, limiting the discovery and applications of mem-RNA. In this study, we propose the first all-in-one solution for high-purity mem-RNA isolation based on two types of magnetic nanoparticles, named MREMB (Membrane-associated RNA Extraction based on Magnetic Beads), which achieved ten times enrichment of cell membrane components and over 90% recovery rate of RNA extraction. To demonstrate MREMB's potential in clinical research, we extracted and sequenced mem-RNA of typical breast cancer MCF-7, MDA-MB-231, and SKBR-3 cell lines and non-neoplastic breast epithelial cell MCF-10A. Compared to total RNA, sequencing results revealed that membrane/secreted protein-encoding mRNAs and long noncoding RNAs (lncRNAs) were enriched in the mem-RNA, some of which were significantly overexpressed in the three cancer cell lines, including extracellular matrix-related genes COL5A1 and lncRNA TALAM1. The results indicated that MREMB could enrich membrane/secreted protein-coding RNA and amplify the expression differences of related RNAs between cancer and non-neoplastic cells, promising for cancer biomarker discovery.

The role of long non-coding RNAs in breast cancer microenvironment

The tumor microenvironment (TME), which includes tumor cells, fibroblasts, endothelial cells, immune cells, and blood vessels, can affect tumor growth and metastasis. Studies have shown that tumor cells, fibroblasts, and macrophages can promote the development of tumors, while T and B cells can inhibit tumor progression. The crosstalk among different cells within the TME needs further study. Long non-coding RNAs (lncRNAs) are involved in biological processes, including cell proliferation, migration, and differentiation. The abnormal expression of certain lncRNAs is correlated with the progression of breast cancer and has been proven as diagnostic markers in various cancers, including breast cancer. In breast cancer, recent studies have shown that tumor cell- and non-tumor cell-derived lncRNAs can affect various facets of tumor progression, including growth, proliferation, and migration of tumor cells. Interestingly, in addition to being regulated by lncRNAs derived from tumor and non-tumor cells, the TME can regulate the expression of lncRNAs in tumor cells, fibroblasts, and macrophages, influencing their phenotype and function. However, the detailed molecular mechanisms of these phenomena remain unclear in the breast cancer microenvironment. Currently, many studies have shown that TME-associated lncRNAs are potential diagnostic and therapeutic targets for breast cancer. Considering that TME and lncRNAs can regulate each other, we summarize the role of lncRNAs in the breast cancer microenvironment and the potential of lncRNAs as valuable diagnostic markers.

Navigating the Blood-Brain Barrier: Challenges and Therapeutic Strategies in Breast Cancer Brain Metastases

Breast cancer (BC) is the most common cancer in women, with metastatic BC being responsible for the highest number of deaths. A frequent site for BC metastasis is the brain. Brain metastasis derived from BC involves the cooperation of multiple genetic, epigenetic, angiogenic, and tumor-stroma interactions. Most of these interactions provide a unique opportunity for development of new therapeutic targets. Potentially targetable signaling pathways are Notch, Wnt, and the epidermal growth factor receptors signaling pathways, all of which are linked to driving BC brain metastasis (BCBM). However, a major challenge in treating brain metastasis remains the blood-brain barrier (BBB). This barrier restricts the access of unwanted molecules, cells, and targeted therapies to the brain parenchyma. Moreover, current therapies to treat brain metastases, such as stereotactic radiosurgery and whole-brain radiotherapy, have limited efficacy. Promising new drugs like phosphatase and kinase modulators, as well as BBB disruptors and immunotherapeutic strategies, have shown the potential to ease the disease in preclinical studies, but remain limited by multiple resistance mechanisms. This review summarizes some of the current understanding of the mechanisms involved in BC brain metastasis and highlights current challenges as well as opportunities in strategic designs of potentially successful future therapies.

Functional impact of non-coding RNAs in high-grade breast carcinoma: Moving from resistance to clinical applications: A comprehensive review

Despite the recent advances in cancer therapy, triple-negative breast cancers (TNBCs) are the most relapsing cancer sub-type. It is partly due to their propensity to develop resistance against the available therapies. An intricate network of regulatory molecules in cellular mechanisms leads to the development of resistance in tumors. Non-coding RNAs (ncRNAs) have gained widespread attention as critical regulators of cancer hallmarks. Existing research suggests that aberrant expression of ncRNAs modulates the oncogenic or tumor suppressive signaling. This can mitigate the responsiveness of efficacious anti-tumor interventions. This review presents a systematic overview of biogenesis and down streaming molecular mechanism of the subgroups of ncRNAs. Furthermore, it explains ncRNA-based strategies and challenges to target the chemo-, radio-, and immunoresistance in TNBCs from a clinical standpoint.

The covert symphony: cellular and molecular accomplices in breast cancer metastasis

Breast cancer has emerged as the most commonly diagnosed cancer and primary cause of cancer-related deaths among women worldwide. Although significant progress has been made in targeting the primary tumor, the effectiveness of systemic treatments to prevent metastasis remains limited. Metastatic disease continues to be the predominant factor leading to fatality in the majority of breast cancer patients. The existence of a prolonged latency period between initial treatment and eventual recurrence in certain patients indicates that tumors can both adapt to and interact with the systemic environment of the host, facilitating and sustaining the progression of the disease. In order to identify potential therapeutic interventions for metastasis, it will be crucial to gain a comprehensive framework surrounding the mechanisms driving the growth, survival, and spread of tumor cells, as well as their interaction with supporting cells of the microenvironment. This review aims to consolidate recent discoveries concerning critical aspects of breast cancer metastasis, encompassing the intricate network of cells, molecules, and physical factors that contribute to metastasis, as well as the molecular mechanisms governing cancer dormancy.

The impact of lipid metabolism on breast cancer: a review about its role in tumorigenesis and immune escape

BACKGROUND

Breast cancer (BC) is the second most frequent type of cancer in the world and most common among women, configuring a major challenge to global health. BC is a complex and heterogeneous disease that can be subdivided into distinct tumor types based on the expression of molecular markers predicting patient outcomes and response to therapy. A growing number of studies have tried to expand the known markers by investigating the association of altered lipid metabolism with BC immune escape, progression, and metastasis. In this review, we describe the metabolic peculiarities of each BC subtype, understanding how this influences its aggressiveness and identifying whether these intrinsic vulnerabilities of each subtype can play a role in therapeutic management and may affect immune system cells in the tumor microenvironment.

CONCLUSION

The evidence suggests so far that when changes occur in lipid pathways, it can affect the availability of structural lipids for membrane synthesis, lipid synthesis, and degradation that contribute to energy homeostasis and cell signaling functions. These findings will guide the next steps on the path to understanding the mechanisms underlying how lipids alterations are related to disparities in chemotherapeutic response and immune escape in BC. Video Abstract.

The current advances of lncRNAs in breast cancer immunobiology research

Breast cancer is the most frequently diagnosed malignancy and the leading cause of cancer-related death in women worldwide. Breast cancer development and progression are mainly associated with tumor-intrinsic alterations in diverse genes and signaling pathways and with tumor-extrinsic dysregulations linked to the tumor immune microenvironment. Significantly, abnormal expression of lncRNAs affects the tumor immune microenvironment characteristics and modulates the behavior of different cancer types, including breast cancer. In this review, we provide the current advances about the role of lncRNAs as tumor-intrinsic and tumor-extrinsic modulators of the antitumoral immune response and the immune microenvironment in breast cancer, as well as lncRNAs which are potential biomarkers of tumor immune microenvironment and clinicopathological characteristics in patients, suggesting that lncRNAs are potential targets for immunotherapy in breast cancer.

Biology of breast cancer brain metastases and novel therapies targeting the blood brain barrier: an updated review

Brain metastasis (BM) is a critical cause of morbidity and mortality in patients with breast cancer (BC). Compared with other cancer cells, BC cells (BCs) exhibit special features in the metastatic process. However, the underlying mechanisms are still unclear, especially the crosstalk between tumour cells and the microenvironment. To date, novel therapies for BM, including targeted therapy and antibody‒drug conjugates, have been developed. Due to an improved understanding of the blood‒brain barrier (BBB) and blood-tumour barrier (BTB), the development and testing of therapeutic agents in clinical phases have substantially increased. However, these therapies face a major challenge due to the low penetration of the BBB or BTB. As a result, researchers have increasingly focused on finding ways to promote drug penetration through these barriers. This review provides an updated overview of breast cancer brain metastases (BCBM) and summarizes the newly developed therapies for BCBM, especially drugs targeting the BBB or BTB.

Long non-coding RNAs in breast cancer stem cells

Breast cancer, one of the most commonly diagnosed cancers worldwide, is a heterogeneous disease with high rates of recurrence and metastasis that contribute to its high mortality rate. Breast cancer stem cells (BCSCs) are a small but significant subset of heterogeneous breast cancer cells that possess stem cell characteristics such as self-renewal and differentiation abilities that may drive metastasis and recurrence. Long non-coding RNAs (lncRNAs) are a class of RNAs that are longer than 200 nucleotides in length and do not possess protein-coding properties. An increasing number of studies have shown that some lncRNAs are abnormally expressed in BCSCs, and have great biological significance in the occurrence, progression, invasion, and metastasis of various cancers. However, the importance of lncRNAs, as well as the molecular mechanisms that regulate and promote the stemness of BCSCs, are still poorly understood. In the current review, we aim to summarize recent studies that highlight the role of lncRNAs in tumor occurrence and progression through BCSCs. In addition, the utility of lncRNAs as biomarkers of breast cancer progression, and their potential use as therapeutic targets for treatment of breast cancer, will be discussed.

Insights into N6-methyladenosine (m6A) modification of noncoding RNA in tumor microenvironment

N6-methyladenosine (m6A) is the most abundant RNA modification in eukaryotes, and it participates in the regulation of pathophysiological processes in various diseases, including malignant tumors, by regulating the expression and function of both coding and non-coding RNAs (ncRNAs). More and more studies demonstrated that m6A modification regulates the production, stability, and degradation of ncRNAs and that ncRNAs also regulate the expression of m6A-related proteins. Tumor microenvironment (TME) refers to the internal and external environment of tumor cells, which is composed of numerous tumor stromal cells, immune cells, immune factors, and inflammatory factors that are closely related to tumors occurrence and development. Recent studies have suggested that crosstalk between m6A modifications and ncRNAs plays an important role in the biological regulation of TME. In this review, we summarized and analyzed the effects of m6A modification-associated ncRNAs on TME from various perspectives, including tumor proliferation, angiogenesis, invasion and metastasis, and immune escape. Herein, we showed that m6A-related ncRNAs can not only be expected to become detection markers of tumor tissue samples, but can also be wrapped into exosomes and secreted into body fluids, thus exhibiting potential as markers for liquid biopsy. This review provides a deeper understanding of the relationship between m6A-related ncRNAs and TME, which is of great significance to the development of a new strategy for precise tumor therapy.

Molecular landscape and emerging therapeutic strategies in breast cancer brain metastasis

Breast cancer (BC) is the most commonly diagnosed cancer worldwide. Advanced BC with brain metastasis (BM) is a major cause of mortality with no specific or effective treatment. Therefore, better knowledge of the cellular and molecular mechanisms underlying breast cancer brain metastasis (BCBM) is crucial for developing novel therapeutic strategies and improving clinical outcomes. In this review, we focused on the latest advances and discuss the contribution of the molecular subtype of BC, the brain microenvironment, exosomes, miRNAs/lncRNAs, and genetic background in BCBM. The blood–brain barrier and blood–tumor barrier create challenges to brain drug delivery, and we specifically review novel approaches to bypass these barriers. Furthermore, we discuss the potential application of immunotherapies and genetic editing techniques based on CRISPR/Cas9 technology in treating BCBM. Emerging techniques and research findings continuously shape our views of BCBM and contribute to improvements in precision therapies and clinical outcomes.

The role of tumor-derived extracellular vesicles containing noncoding RNAs in mediating immune cell function and its implications from bench to bedside

Extracellular vesicles (EVs) are membrane-encapsulated vesicles released by almost all cell types, which participate in intercellular communication by delivering different types of molecular cargoes, such as non-coding RNAs (ncRNAs). Accumulating evidence suggests that tumor-derived EVs act as a bridge for intercellular crosstalk between tumor cells and surrounding cells, including immune cells. Tumor-derived EVs containing ncRNAs (TEV-ncRNAs) mediate intercellular crosstalk to manipulate immune responses and affect the malignant phenotypes of cancer cells. In this review, we summarize the double-edged roles and the underlying mechanisms of TEV-ncRNAs in regulating innate and adaptive immune cells. We also highlight the advantages of using TEV-ncRNAs in liquid biopsies for cancer diagnosis and prognosis. Moreover, we outline the use of engineered EVs to deliver ncRNAs and other therapeutic agents for cancer therapy.

Exosomes; multifaceted nanoplatform for targeting brain cancers

At the moment, anaplastic changes within the brain are challenging due to the complexity of neural tissue, leading to the inefficiency of therapeutic protocols. The existence of a cellular interface, namely the blood-brain barrier (BBB), restricts the entry of several macromolecules and therapeutic agents into the brain. To date, several nano-based platforms have been used in laboratory settings and in vivo conditions to overcome the barrier properties of BBB. Exosomes (Exos) are one-of-a-kind of extracellular vesicles with specific cargo to modulate cell bioactivities in a paracrine manner. Regarding unique physicochemical properties and easy access to various biofluids, Exos provide a favorable platform for drug delivery and therapeutic purposes. Emerging data have indicated that Exos enable brain penetration of selective cargos such as bioactive factors and chemotherapeutic compounds. Along with these statements, the application of smart delivery approaches can increase delivery efficiency and thus therapeutic outcomes. Here, we highlighted the recent advances in the application of Exos in the context of brain tumors.

Extracellular vesicle-derived LINC00482 induces microglial M2 polarization to facilitate brain metastasis of NSCLC

Considering the crucial role of long non-coding RNAs (lncRNAs) in non-small cell lung cancer (NSCLC), we tried to analyze the role of extracellular vesicle (EV)-derived LINC00482 in the occurrence of brain metastasis in NSCLC. LINC00482 expression was quantified in EVs isolated from serum samples of NSCLC patients (serum-EVs). Ectopic expression and depletion assays were conducted in the microglial cell line HMC3 co-cultured with serum-EVs and in xenograft mouse models of NSCLC to explore the roles of EV-carried LINC00482. LINC00482 was enriched in serum-EVs and induced M2 polarization of microglial cells HMC3 in vitro. LINC00482 competitively bound to miR-142-3p and upregulated the expression of miR-142-3p target gene TGF-β1 in HMC3 cells, thus promoting microglial M2 polarization. EV-derived LINC00482-induced M2 microglia promoted the malignant properties of NSCLC cells. In vivo data demonstrated that EVs transmitted LINC00482 to regulate the miR-142-3p/TGF-β1 axis, induce microglial M2 polarization and affect the pre-metastatic niche, thus enhancing brain metastasis of NSCLC. Overall, suppression of the expression of tumor-derived LINC00482 or LINC00482-containing EVs, may serve as an effective target for contributing to the reduction of brain metastasis of NSCLC.

Macrophages at the interface of the co-evolving cancer ecosystem

Macrophages are versatile and heterogeneous innate immune cells undertaking central functions in balancing immune responses and tissue repair to maintain homeostasis. This plasticity, once co-opted by malignant outgrowth, orchestrates manifold reciprocal interactions within the tumor microenvironment, fueling the evolution of the cancer ecosystem. Here, we review the multilayered sources of influence that jointly underpin and longitudinally shape tumor-associated macrophage (TAM) phenotypic states in solid neoplasms. We discuss how, in response to these signals, TAMs steer tumor evolution in the context of natural selection, biological dispersion, and treatment resistance. A number of research frontiers to be tackled are laid down in this review to therapeutically exploit the complex roles of TAMs in cancer. Building upon knowledge obtained from currently applied TAM-targeting strategies and using next generation technologies, we propose conceptual advances and novel therapeutic avenues to rewire TAM multifaceted regulation of the co-evolving cancer ecosystem.

Immune determinants of the pre-metastatic niche

Primary tumors actively and specifically prime pre-metastatic niches (PMNs), the future sites of organotropic metastasis, preparing these distant microenvironments for disseminated tumor cell arrival. While initial studies of the PMN focused on extracellular matrix alterations and stromal reprogramming, it is increasingly clear that the far-reaching effects of tumors are in great part achieved through systemic and local PMN immunosuppression. Here, we discuss recent advances in our understanding of the tumor immune microenvironment and provide a comprehensive overview of the immune determinants of the PMN's spatiotemporal evolution. Moreover, we depict the PMN immune landscape, based on functional pre-clinical studies as well as mounting clinical evidence, and the dynamic, reciprocal crosstalk with systemic changes imposed by cancer progression. Finally, we outline emerging therapeutic approaches that alter the dynamics of the interactions driving PMN formation and reverse immunosuppression programs in the PMN ensuring early anti-tumor immune responses.