Chemotherapy-induced exosomal circBACH1 promotes breast cancer resistance and stemness via miR-217/G3BP2 signaling pathway

Enhanced pharmacokinetic approach for anastrozole via macromolecule-based silk fibroin nanoparticles incorporated in situ injectables for oestrogen-positive breast cancer therapy

Breast cancer (BC) is a substantial reason for cancer-related mortality among women across the globe. Anastrozole (ANS) is an effective orally administered hormonal therapy for oestrogen-positive (ER+) BC treatment. However, several side effects and pharmacokinetic limitations restricted the uses of ANS in BC therapy. Therefore, this investigation developed an in situ gelling injectable-loaded silk fibroin (SF)-ANS NPs, which offers sustained drug release and improved pharmacokinetic properties compared to conventional oral formulations at the targeted site. The optimised in situ gel (ISG) incorporated SF-ANS-NPs were developed, and the pharmacokinetic parameters were accessed in subcutaneous administration of NMU-induced Wistar albino rats. The results demonstrated that SF-ANS-NP-ISG exhibited a significantly higher Cmax, Tmax, and AUC compared to pure ANS suspension. In addition, tumour multiplicity (1.40 ± 0.66), tumour latency (75 ± 9.2 days), and incidence rate (90 ± 2.1%) were recorded, and post-treatment analysis reported a marked reduction in tumour volume and weight compared to positive control within 90 days of a single dose. The SF-ANS-NP-ISG treated group's histopathological assessment indicated a low-grade carcinoma, reduced epithelial hyperplasia, and haemorrhage in mammary tumour tissues compared to positive control. Thus, the SF-ANS-NPs-ISG investigated to overcome the pharmacokinetic limitations of ANS further exhibited targeted delivery and bioavailability compared to conventional dosage forms.

Exosomal circRNAs: key modulators in breast cancer progression

Breast cancer (BC) poses significant challenges globally, necessitating a deeper understanding of its complexities. Exosomes are cell-specific secreted extracellular vesicles of interest, characterized by a lipid bilayer structure. Exosomes can carry a variety of bioactive components, including nucleic acids, lipids, amino acids, and small molecules, to mediate intercellular signaling. CircRNAs are a novel class of single-stranded RNA molecules, characterized by a closed-loop structure. CircRNAs mainly exert ceRNA functions to intricately modulate gene expression and signaling pathways in breast cancer, influencing tumor progression and therapeutic responses. The unique packaging of circRNAs within exosomes serves as novel genetic information transmitters, facilitating communication between BC cells and microenvironmental cells, thereby regulating critical aspects of BC progression, immune evasion, and drug resistance. Besides, exosomal circRNAs possess the capabilities of serving as diagnostic and therapeutic biomarkers of BC, due to their stability, specificity, and regulatory roles in tumorigenesis and metastasis. Therefore, this review aims to elucidate the novel roles and mechanisms of exosomal circRNAs in BC progression, as well as their potential for diagnosis and therapeutics. The ongoing investigations of exosomal circRNAs will potentially revolutionize treatment paradigms and improve patient outcomes of BC.

Exosome-Mediated Cellular Communication in the Tumor Microenvironment Imparts Drug Resistance in Breast Cancer

Globally, breast cancer (BC) is the leading cause of cancer-related death for women. BC is characterized by heterogeneity, aggressive behavior, and high metastatic potential. Chemotherapy, administered as monotherapy or adjuvant therapy, remains a cornerstone of treatment; however, acquired drug resistance is a significant clinical challenge. Deciphering mechanisms of drug resistance will be central to developing more efficient treatment options and improving patient outcomes. The current review examines the multifaceted nature of exosomes in conferring drug resistance in BC through complex communication networks within the tumor microenvironment. We further explore recent advances in understanding how exosomes contribute to resistance against established chemotherapeutic agents such as tamoxifen, paclitaxel, doxorubicin, platinum-based drugs, trastuzumab, and newer immunotherapies, such as immune checkpoint inhibitors. Moreover, we discuss existing systematic approaches to investigating the exosome-drug resistance relationship in BC. Finally, we explore promising therapeutic approaches to overcome exosome-dependent drug resistance in BC, highlighting potential avenues for improved treatment efficacy. Investigating the distinct functions and cargo of exosomes offers potential for developing innovative approaches to overcoming treatment resistance.

Role of circular RNAs in cancer therapy resistance

Over the past decade, circular RNAs (circRNAs) have gained recognition as a novel class of genetic molecules, many of which are implicated in cancer pathogenesis via different mechanisms, including drug resistance, immune escape, and radio-resistance. ExosomalcircRNAs, in particular, facilitatecommunication between tumour cells and micro-environmental cells, including immune cells, fibroblasts, and other components. Notably, micro-environmental cells can reportedly influence tumour progression and treatment resistance by releasing exosomalcircRNAs. circRNAs often exhibit tissue- and cancer-specific expression patterns, and growing evidence highlights their potential clinical relevance and utility. These molecules show strong promise as potential biomarkers and therapeutic targets for cancer diagnosis and treatment. Therefore, this review aimed to briefly discuss the latest findings on the roles and resistance mechanisms of key circRNAs in the treatment of various malignancies, including lung, breast, liver, colorectal, and gastric cancers, as well as haematological malignancies and neuroblastoma.This review will contribute to the identification of new circRNA biomarkers for the early diagnosis as well as therapeutic targets for the treatment of cancer.

Circular RNAs in cancer

Circular RNA (circRNA), a subtype of noncoding RNA, has emerged as a significant focus in RNA research due to its distinctive covalently closed loop structure. CircRNAs play pivotal roles in diverse physiological and pathological processes, functioning through mechanisms such as miRNAs or proteins sponging, regulation of splicing and gene expression, and serving as translation templates, particularly in the context of various cancers. The hallmarks of cancer comprise functional capabilities acquired during carcinogenesis and tumor progression, providing a conceptual framework that elucidates the nature of the malignant transformation. Although numerous studies have elucidated the role of circRNAs in the hallmarks of cancers, their functions in the development of chemoradiotherapy resistance remain unexplored and the clinical applications of circRNA-based translational therapeutics are still in their infancy. This review provides a comprehensive overview of circRNAs, covering their biogenesis, unique characteristics, functions, and turnover mechanisms. We also summarize the involvement of circRNAs in cancer hallmarks and their clinical relevance as biomarkers and therapeutic targets, especially in thyroid cancer (TC). Considering the potential of circRNAs as biomarkers and the fascination of circRNA-based therapeutics, the "Ying-Yang" dynamic regulations of circRNAs in TC warrant vastly dedicated investigations.

The role of ceRNAs in breast cancer microenvironmental regulation and therapeutic implications

The tumor microenvironment, which is the tailored physiological milieu of heterogeneous cancer cell populations surrounded by stromal and immune cells as well as extracellular matrix components, is a leading modulator of critical cancer hallmarks and one of the most significant prognostic indicators in breast cancer. In the last few decades, with the discovery of the interactions of ncRNAs with diverse cellular molecules, considerable emphasis has been devoted to understanding their direct and indirect roles in specific functions in breast cancer. Collectively, all of these have revealed that the competitive action of protein-coding RNAs and ncRNAs such as circRNAs and lncRNAs, which have a shared affinity for miRNAs, play a vital role in the molecular regulation of breast cancer. This phenomenon, termed as competing endogenous RNAs (ceRNAs), facilitates modeling the microenvironment through intercellular shuttles. Microenvironment ceRNA interactions have emerged as a frontier in the deep understanding of the complex mechanisms of breast cancer. In this review, we first discuss cellular ceRNAs in four key biological processes critical for microenvironmental regulation in breast cancer tissues: hypoxia, angiogenesis, immune regulations, and ECM remodeling. Further, we draw a complete portrait of microenvironment regulation by cell-to-cell cross-talk of shuttled ceRNAs and offer a framework of potential applications and challenges in overcoming the aggressive phenotype of the breast cancer microenvironment.

Exosomal circular RNAs in tumor microenvironment: An emphasis on signaling pathways and clinical opportunities

Exosomes can regulate the malignant progression of tumors by carrying a variety of genetic information and transmitting it to target cells. Recent studies indicate that exosomal circular RNAs (circRNAs) regulate multiple biological processes in carcinogenesis, such as tumor growth, metastasis, epithelial-mesenchymal transition, drug resistance, autophagy, metabolism, angiogenesis, and immune escape. In the tumor microenvironment (TME), exosomal circRNAs can be transferred among tumor cells, endothelial cells, cancer-associated fibroblasts, immune cells, and microbiota, affecting tumor initiation and progression. Due to the high stability and widespread presence of exosomal circRNAs, they hold promise as biomarkers for tumor diagnosis and prognosis prediction in blood and urine. In addition, designing nanoparticles targeting exosomal circRNAs and utilizing exosomal circRNAs derived from immune cells or stem cells provide new strategies for cancer therapy. In this review, we examined the crucial role of exosomal circRNAs in regulating tumor-related signaling pathways and summarized the transmission of exosomal circRNAs between various types of cells and their impact on the TME. Finally, our review highlights the potential of exosomal circRNAs as diagnostic and prognostic prediction biomarkers, as well as suggesting new strategies for clinical therapy.

Hsa_circRNA_000166 accelerates breast cancer progression via the regulation of the miR-326/ELK1 and miR-330-5p/ELK1 axes

PURPOSES

To probe the expression, clinical significance, roles, and molecular mechanisms of circRNA_000166 in breast cancer (BC).

METHODS

Clinical tissue samples were gathered from 84 BC patients who underwent surgery at the Affiliated Hospital of Chengde Medical College. Clinical data were obtained from medical records and postoperative follow-up. Expression levels of circRNA_000166, miR-326, miR-330-5p, and ELK1 mRNA in BC tissues and cells were measured by qRT-PCR, and ELK1 protein levels were assessed by WB. Pearson's correlation analysis evaluated the interrelationships between these RNAs in clinical samples. Luciferase reporter assays verified the interactions between miR-326/miR-330-5p and circRNA_000166, as well as between miR-326/miR-330-5p and ELK1. Cell proliferation, migration, and apoptosis were examined using CCK-8, colony formation, transwell, and flow cytometry assays, respectively.

RESULTS

CircRNA_000166 was highly expressed in BC tissues and inversely correlated with miR-326/miR-330-5p levels but positively with ELK1 mRNA levels. ELK1 mRNA also inversely associated with miR-326/miR-330-5p levels in BC tissues. Importantly, our findings demonstrated that circRNA_000166 targets miR-326 and miR-330-5p, while ELK1 is the target of miR-326 and miR-330-5p in BC cells. CircRNA_000166 levels positively correlated with tumour size, TNM stage, histological grade, and lymph node metastasis, and negatively associated with postoperative progression-free survival (PFS) and overall survival (OS) in BC patients. CircRNA_000166 was also highly expressed in BC cells, and knockdown of circRNA_000166 reduced proliferation and migration, and increased apoptosis via miR-326/ELK1 and miR-330-5p/ELK1 pathways in vitro.

CONCLUSION

CircRNA_000166 enhances BC progression through miR-326/ELK1 and miR-330-5p/ELK1 pathways and shows potential as a biomarker for BC diagnosis and treatment.

Transcriptional regulation of DLGAP5 by AR suppresses p53 signaling and inhibits CD8+T cell infiltration in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a challenging subtype with unclear biological mechanisms. Recently, the transcription factor androgen receptor (AR) and its regulation of the DLGAP5 gene have gained attention in TNBC pathogenesis. In this study, we found a positive correlation between high AR expression and TNBC cell proliferation and growth. Furthermore, we confirmed DLGAP5 as a critical downstream regulator of AR with high expression in TNBC tissues. Knockdown of DLGAP5 significantly inhibited TNBC cell proliferation, migration, and invasion. AR was observed to directly bind to the DLGAP5 promoter, enhancing its transcriptional activity and suppressing the activation of the p53 signaling pathway. In vivo experiments further validated that downregulation of AR or DLGAP5 inhibited tumor growth and enhanced CD8+T cell infiltration. This study highlights the crucial roles of AR and DLGAP5 in TNBC growth and immune cell infiltration. Taken together, AR inhibits the p53 signaling pathway by promoting DLGAP5 expression, thereby impacting CD8+T cell infiltration in TNBC.

Potential therapies for non-coding RNAs in breast cancer

Breast cancer (BC) is one of the frequent tumors that seriously endanger the physical and mental well-being in women with strong heterogeneity, and its pathogenesis involves multiple risk factors. Depending on the type of BC, hormonal therapy, targeted therapy, and immunotherapy are the current systemic treatment options along with conventional chemotherapy. Despite significant progress in understanding BC pathogenesis and therapeutic options, there is still a need to identify new therapeutic targets and develop more effective treatments. According to recent sequencing and profiling studies, non-coding (nc) RNAs genes are deregulated in human cancers via deletion, amplification, abnormal epigenetic, or transcriptional regulation, and similarly, the expression of many ncRNAs is altered in breast cancer cell lines and tissues. The ability of single ncRNAs to regulate the expression of multiple downstream gene targets and related pathways provides a theoretical basis for studying them for cancer therapeutic drug development and targeted delivery. Therefore, it is far-reaching to explore the role of ncRNAs in tumor development and their potential as therapeutic targets. Here, our review outlines the potential of two major ncRNAs, long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) as diagnostic and prognostic biomarkers as well as targets for new therapeutic strategies in breast cancer.

Hsa_circ_0007590/PTBP1 complex reprograms glucose metabolism by reducing the stability of m6A-modified PTEN mRNA in pancreatic ductal adenocarcinoma

The role of circular RNAs (circRNAs) in glucose metabolism in pancreatic duct adenocarcinoma (PDAC) remains elusive. Through RNA sequencing of cells cultured under conditions of glucose deprivation, we identified hsa_circ_0007590. Sanger sequencing and RNase R and Act D treatments were performed to confirm the circular RNA features of hsa_circ_0007590. RNA in situ hybridization (RNA-ISH) and quantitative reverse transcription PCR (qRT-PCR) were used to estimate hsa_circ_0007590 expression in PDAC clinical specimens and cell lines. hsa_circ_0007590 expression was higher in PDAC patients and closely related to the clinicopathological characteristics of the disease. Cytoplasm‒nuclear fractionation and FISH assays demonstrated that hsa_circ_0007590 was located in the nucleus. Gain-of-function and loss-of-function assays were performed to assess the biological behaviors of PDAC cells. Seahorse XF assays were performed to validate the Warburg effect. hsa_circ_0007590 facilitated the proliferation, migration, and invasion of PDAC cells and promoted the Warburg effect. Mass spectrometry, RNA pulldown, RNA immunoprecipitation (RIP), RNA m6A quantification, m6A dot blot, MeRIP, and Western blotting were conducted to investigate the detailed mechanism through which hsa_circ_0007590 produces these effects. Mechanistically, hsa_circ_0007590 targeted PTBP1 and increased the expression of the m6A reader protein YTHDF2, leading to PTEN mRNA degradation and PI3K/AKT/mTOR pathway activation. Overall, hsa_circ_0007590, which targets PTBP1, reprograms glucose metabolism by attenuating the stability of m6A-modified PTEN mRNA and holds potential promise as a therapeutic target for PDAC.

Research progress in tumor angiogenesis and drug resistance in breast cancer

Angiogenesis is considered a hallmark pathophysiological process in tumor development. Aberrant vasculature resulting from tumor angiogenesis plays a critical role in the development of resistance to breast cancer treatments, via exacerbation of tumor hypoxia, decreased effective drug concentrations within tumors, and immune-related mechanisms. Antiangiogenic therapy can counteract these breast cancer resistance factors by promoting tumor vascular normalization. The combination of antiangiogenic therapy with chemotherapy, targeted therapy, or immunotherapy has emerged as a promising approach for overcoming drug resistance in breast cancer. This review examines the mechanisms associated with angiogenesis and the interactions among tumor angiogenesis, the hypoxic tumor microenvironment, drug distribution, and immune mechanisms in breast cancer. Furthermore, this review provides a comprehensive summary of specific antiangiogenic drugs, and relevant studies assessing the reversal of drug resistance in breast cancer. The potential mechanisms underlying these interventions are discussed, and prospects for the clinical application of antiangiogenic therapy to overcome breast cancer treatment resistance are highlighted.

The prognostic genes model of breast cancer drug resistance based on single-cell sequencing analysis and transcriptome analysis

Breast cancer (BC) represents a multifaceted malignancy, with escalating incidence and mortality rates annually. Chemotherapy stands as an indispensable approach for treating breast cancer, yet drug resistance poses a formidable challenge. Through transcriptome data analysis, we have identified two sets of genes exhibiting differential expression in this context. Furthermore, we have confirmed the overlap between these genes and those associated with exosomes, which were subsequently validated in cell lines. The investigation screened the identified genes to determine prognostic markers for BC and utilized them to formulate a prognostic model. The disparities in prognosis and immunity between the high- and low-risk groups were validated using the test dataset. We have discerned different BC subtypes based on the expression levels of prognostic genes in BC samples. Variations in prognosis, immunity, and drug sensitivity among distinct subtypes were examined. Leveraging data from single-cell sequencing and prognostic gene expression, the AUCell algorithm was employed to score individual cell clusters and analyze the pathways implicated in high-scoring groups. Prognostic genes (CCT4, CXCL13, MTDH, PSMD2, and RAB27A) were subsewoquently validated using RT-qPCR. Consequently, we have established a model for predicting prognosis in breast cancer that hinges on drug resistance and ERGs. Furthermore, we have evaluated the prognostic value of this model. The genes identified as prognostic markers can now serve as a reference for precise treatment of this condition.

Drug resistance in breast cancer is based on the mechanism of exocrine non-coding RNA

Breast cancer (BC) ranks first among female malignant tumors and involves hormonal changes and genetic as well as environmental risk factors. In recent years, with the improvement of medical treatment, a variety of therapeutic approaches for breast cancer have emerged and have strengthened to accommodate molecular diversity. However, the primary way to improve the effective treatment of breast cancer patients is to overcome treatment resistance. Recent studies have provided insights into the mechanisms of resistance to exosome effects in BC. Exosomes are membrane-bound vesicles secreted by both healthy and malignant cells that facilitate intercellular communication. Specifically, exosomes released by tumor cells transport their contents to recipient cells, altering their properties and promoting oncogenic components, ultimately resulting in drug resistance. As important coordinators, non-coding RNAs (ncRNAs) are involved in this process and are aberrantly expressed in various human cancers. Exosome-derived ncRNAs, including microRNAs (miRNAs), long-noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), have emerged as crucial components in understanding drug resistance in breast cancer. This review provides insights into the mechanism of exosome-derived ncRNAs in breast cancer drug resistance, thereby suggesting new strategies for the treatment of BC.

Extracellular vesicles as tools and targets in therapy for diseases

Extracellular vesicles (EVs) are nano-sized, membranous structures secreted into the extracellular space. They exhibit diverse sizes, contents, and surface markers and are ubiquitously released from cells under normal and pathological conditions. Human serum is a rich source of these EVs, though their isolation from serum proteins and non-EV lipid particles poses challenges. These vesicles transport various cellular components such as proteins, mRNAs, miRNAs, DNA, and lipids across distances, influencing numerous physiological and pathological events, including those within the tumor microenvironment (TME). Their pivotal roles in cellular communication make EVs promising candidates for therapeutic agents, drug delivery systems, and disease biomarkers. Especially in cancer diagnostics, EV detection can pave the way for early identification and offers potential as diagnostic biomarkers. Moreover, various EV subtypes are emerging as targeted drug delivery tools, highlighting their potential clinical significance. The need for non-invasive biomarkers to monitor biological processes for diagnostic and therapeutic purposes remains unfulfilled. Tapping into the unique composition of EVs could unlock advanced diagnostic and therapeutic avenues in the future. In this review, we discuss in detail the roles of EVs across various conditions, including cancers (encompassing head and neck, lung, gastric, breast, and hepatocellular carcinoma), neurodegenerative disorders, diabetes, viral infections, autoimmune and renal diseases, emphasizing the potential advancements in molecular diagnostics and drug delivery.

Alpha-hederin reprograms multi-miRNAs activity and overcome small extracellular vesicles-mediated paclitaxel resistance in NSCLC

Background: Small extracellular vesicles (sEVs) mediate intercellular communication in the tumor microenvironment (TME) and contribute to the malignant transformation of tumors, including unrestricted growth, metastasis, or therapeutic resistance. However, there is a lack of agents targeting sEVs to overcome or reverse tumor chemotherapy resistance through sEVs-mediated TME reprogramming. Methods: The paclitaxel (PTX)-resistant A549T cell line was used to explore the inhibitory effect of alpha-hederin on impeding the transmission of chemoresistance in non-small cell lung cancer (NSCLC) through the small extracellular vesicles (sEVs) pathway. This investigation utilized the CCK-8 assay and flow cytometry. Transcriptomics, Western blot, oil red O staining, and targeted metabolomics were utilized to evaluate the impact of alpha-hederin on the expression of signaling pathways associated with chemoresistance transmission in NSCLC cells before and after treatment. In vivo molecular imaging and immunohistochemistry were conducted to assess how alpha-hederin influences the transmission of chemoresistance through the sEVs pathway. RT-PCR was employed to examine the expression of miRNA and lncRNA in response to alpha-hederin treatment. Results: The resistance to PTX chemotherapy in A549T cells was overcome by alpha-hederin through its dependence on sEV secretion. However, the effectiveness of alpha-hederin was compromised when vesicle secretion was blocked by the GW4869 inhibitor. Transcriptomic analysis for 463 upregulated genes in recipient cells exposed to A549T-derived sEVs revealed that these sEVs enhanced TGFβ signaling and unsaturated fatty acid synthesis pathways. Alpha-hederin inhibited 15 types of unsaturated fatty acid synthesis by reducing the signaling activity of the sEVs-mediated TGFβ/SMAD2 pathway. Further, we observed that alpha-hederin promoted the production of three microRNAs (miRNAs, including miR-21-5p, miR-23a-3p, and miR-125b-5p) and the sorting to sEVs in A549T cells. These miRNAs targeted the TGFβ/SMADs signaling activity in sEVs-recipient cells and sensitized them to the PTX therapy. Conclusion: Our finding demonstrated that alpha-hederin could sensitize PTX-resistant NSCLC cells by sEV-mediated multiple miRNAs accumulation, and inhibiting TGFβ/SMAD2 pathways in recipient cells.

[High expression of secretogranin II increases oxaliplatin resistance of colorectal cancer cells]

OBJECTIVE

To investigate the expression of secretogranin II (SCG2) in colorectal cancer (CRC) tissues and its impact on oxaliplatin resistance of CRC cells.

METHODS

We performed immunohistochemistry to detect the expression level of SCG2 on a tissue microarray containing 96 CRC and 84 adjacent tissues and analyzed the association of SCG2 expression with the clinical features of the CRC patients. SCG2 expression was also measured in DLD1 cells treated with oxaliplatin using immunoblotting and RT-qPCR analyses. The effects of SCG2 expression on oxaliplatin sensitivity and cell viability were evaluated in a DLD1 cell model of SCG2 knockout established using CRISPR-cas9 technique, and the expressions of apoptosis-related proteins were detected using Western blotting and RT-qPCR. We further examined SCG2 expression levels in an oxaliplatin-resistant DLD1 cell line and its parental DLD1 cells.

RESULTS

SCG2 expression was significantly increased in CRC tissues as compared with the adjacent tissues (1.932±0.816 vs 1), and the tumor tissues in advanced stages showed higher SCG2 expression levels. In DLD1 cells, treatment with oxaliplatin significantly increased SCG2 expression, and SCG2 knockout obviously increased oxaliplatin sensitivity of the cells and enhanced the expressions of apoptosis-related proteins. Compared with the parental cells, oxaliplatin-resistant DLD1 cells showed a significant increase of SCG2 expression by 3.901±0.471 folds.

CONCLUSION

SCG2 may serve as a risk gene in CRC, and its high expression increases oxaliplatin resistance of CRC cells.