Hsa_circRNA_007630 knockdown delays colon cancer progression by modulation of ferroptosis via miR-506-3p/AURKA axis.

Colon cancer contributes to high mortality rates internationally that has seriously endangered human health. Aurora kinase A (AURKA) served as a key molecule in colon cancer. However, its role of AURKA on regulating ferroptosis in colon cancer and their possible interactions with miRNAs and circRNAs remain still elusive. Comprehensive bioinformatics analysis after RNA-sequencing was conducted to determine the differentially expressed genes (DEGs), ferroptosis-related DEGs and hub genes. The direct relationship between miR-506-3p and hsa_circRNA_007630 or AURKA was predicted, then verified by dual luciferase reporter and quantitative real-time polymerase chain reaction. The rescue experiments were conducted by cotransfection with si-hsa_circRNA_007630, miR-506-3p inhibitor or pcDNA-AURKA in HT29 cells. Erastin was used to induce ferroptosis in HT29 cells and validated by detecting levels of intracellular Fe2+, lipid reactive oxygen species, glutathione, malondialdehyde and ferroptosis markers expression. We screened a total of 331 DEGs, 26 ferroptosis-related genes, among which 3 hub genes were identified through PPI network analysis. Therein, AURKA expression was elevated in colon cancer cells. Moreover, AURKA was targeted by miR-506-3p, and hsa_circRNA_007630 operated as miR-506-3p sponge. The effect of hsa_circRNA_007630 depletion on the inhibiting malignant phenotypes of HT29 cells was rescued by inhibition of miR-506-3p or AURKA overexpression. Additionally, AURKA reduced erastin-induced ferroptosis in HT29 cells. Depletion of circRNA_007630 exerts as a suppressive role in colon cancer through a novel miR-506-3p/AURKA pathway related to ferroptosis, and might become a novel marker for colon cancer.

CircCOL5A1 is involved in proliferation, invasion, and inhibition of ferroptosis of colorectal cancer cells via miR-1287-5p/SLC7A11.

Colorectal cancer (CRC) is the leading cause of cancer-related death globally. Circular RNA circCOL5A1 plays an oncogene function in a variety of tumors. However, the function of circCOL5A1 in CRC is still unknown. Here, we aimed to elucidate the function and mechanism of circCOL5A1 in CRC. The correlation between circCOL5A1 and CRC clinicopathological was assessed through chi-square. The relevance between circCOL5A1 and CRC patient survival time was evaluated by Kaplan-Meier analysis. The expressions of circCOL5A1 in CRC were determined via quantitative real-time PCR. The function of circCOL5A1 in CRC was analyzed with Cell Counting Kit-8, EdU assay, Transwell, detection of reactive oxygen species and Fe2+ levels, and Western blot analysis. Moreover, the mechanism of circCOL5A1 was determined by dual-luciferase reporter assay, RNA immunoprecipitation, and RNA pull-down. Finally, the role of circCOL5A1 in vivo was elucidated through a mouse xenograft model, hematoxylin-eosin staining, and immunohistochemistry. CircCOL5A1 expression was increased in CRC, and increased circCOL5A1 levels were related to TNM stage, lymph node metastasis, distant metastasis, and tumor differentiation in CRC patients, and CRC patients with high circCOL5A1 levels had a low overall survival rate. For the circCOL5A1 function in CRC, we found that circCOL5A1 knockdown weakened CRC cell proliferation and invasion, and enhanced cell ferroptosis. For the circCOL5A1 mechanism in CRC, we further confirmed that circCOL5A1 bound to miR-1287-5p, miR-1287-5p bound to SLC7A11. SLC7A11 was negatively interrelated to miR-1287-5p and was positively interrelated to circCOL5A1 in CRC tissues. Furthermore, interfering circCOL5A1 decreased SLC7A11 expression, and this trend was abolished through miR-1287-5p cotransfection. Rescue assays further demonstrated that circCOL5A1 knockdown alleviated CRC cell malignant phenotype via miR-1287-5p/SLC7A11. Moreover, interference with circCOL5A1 reduced CRC growth in vivo. CircCOL5A1 functioned as an oncogene in CRC via miR-1287-5p/SLC7A11.

ImmRNA: a database of RNAs associated with tumor immunity.

The relationship between different ribonucleic acids (RNAs) and tumor immunity has been widely investigated. However, a systematic description of tumor immune-related RNAs in different tumors is still lacking. We collected the relationship of tumor immune-related RNAs from the published literature and presented them in a user-friendly interface, "ImmRNA" (http://www.immrna.cn/), to provide a resource to study immune-RNA-cancer regulatory relations. The ImmRNA contains 49 996 curated entries. Each entry includes gene symbols, gene types, target genes, downstream effects, functions, immune cells, and other information. By rearranging and reanalyzing the data, our dataset contains the following key points: (i) providing the links between RNAs and the immune in cancers, (ii) displaying the downstream effects and functions of RNAs, (iii) listing immune cells and immune pathways related to RNA function, (iv) showing the relationship between RNAs and prognostic outcomes, and (v) exhibiting the experimental methods described in the article. ImmRNA provides a valuable resource for understanding the functions of tumor immune-related RNAs. Database URL:  http://www.immrna.cn/.

Mechanisms and clinical landscape of N6-methyladenosine (m6A) RNA modification in gastrointestinal tract cancers.

Epigenetics encompasses reversible and heritable chemical modifications of non-nuclear DNA sequences, including DNA and RNA methylation, histone modifications, non-coding RNA modifications, and chromatin rearrangements. In addition to well-studied DNA and histone methylation, RNA methylation has emerged as a hot topic in biological sciences over the past decade. N6-methyladenosine (m6A) is the most common and abundant modification in eukaryotic mRNA, affecting all RNA stages, including transcription, translation, and degradation. Advances in high-throughput sequencing technologies made it feasible to identify the chemical basis and biological functions of m6A RNA. Dysregulation of m6A levels and associated modifying proteins can both inhibit and promote cancer, highlighting the importance of the tumor microenvironment in diverse biological processes. Gastrointestinal tract cancers, including gastric, colorectal, and pancreatic cancers, are among the most common and deadly malignancies in humans. Growing evidence suggests a close association between m6A levels and the progression of gastrointestinal tumors. Global m6A modification levels are substantially modified in gastrointestinal tumor tissues and cell lines compared to healthy tissues and cells, possibly influencing various biological behaviors such as tumor cell proliferation, invasion, metastasis, and drug resistance. Exploring the diagnostic and therapeutic potential of m6A-related proteins is critical from a clinical standpoint. Developing more specific and effective m6A modulators offers new options for treating these tumors and deeper insights into gastrointestinal tract cancers.

l-2-Hydroxyglutarate remodeling of the epigenome and epitranscriptome creates a metabolic vulnerability in kidney cancer models.

Tumor cells are known to undergo considerable metabolic reprogramming to meet their unique demands and drive tumor growth. At the same time, this reprogramming may come at a cost with resultant metabolic vulnerabilities. The small molecule l-2-hydroxyglutarate (l-2HG) is elevated in the most common histology of renal cancer. Similarly to other oncometabolites, l-2HG has the potential to profoundly impact gene expression. Here, we demonstrate that l-2HG remodels amino acid metabolism in renal cancer cells through combined effects on histone methylation and RNA N6-methyladenosine. The combined effects of l-2HG result in a metabolic liability that renders tumors cells reliant on exogenous serine to support proliferation, redox homeostasis, and tumor growth. In concert with these data, high-l-2HG kidney cancers demonstrate reduced expression of multiple serine biosynthetic enzymes. Collectively, our data indicate that high-l-2HG renal tumors could be specifically targeted by strategies that limit serine availability to tumors.

Oncogenic ETS fusions promote DNA damage and proinflammatory responses via pericentromeric RNAs in extracellular vesicles.

Aberrant expression of the E26 transformation-specific (ETS) transcription factors characterizes numerous human malignancies. Many of these proteins, including EWS:FLI1 and EWS:ERG fusions in Ewing sarcoma (EwS) and TMPRSS2:ERG in prostate cancer (PCa), drive oncogenic programs via binding to GGAA repeats. We report here that both EWS:FLI1 and ERG bind and transcriptionally activate GGAA-rich pericentromeric heterochromatin. The respective pathogen-like HSAT2 and HSAT3 RNAs, together with LINE, SINE, ERV, and other repeat transcripts, are expressed in EwS and PCa tumors, secreted in extracellular vesicles (EVs), and are highly elevated in plasma of patients with EwS with metastatic disease. High human satellite 2 and 3 (HSAT2,3) levels in EWS:FLI1- or ERG-expressing cells and tumors were associated with induction of G2/M checkpoint, mitotic spindle, and DNA damage programs. These programs were also activated in EwS EV-treated fibroblasts, coincident with accumulation of HSAT2,3 RNAs, proinflammatory responses, mitotic defects, and senescence. Mechanistically, HSAT2,3-enriched cancer EVs induced cGAS-TBK1 innate immune signaling and formation of cytosolic granules positive for double-strand RNAs, RNA-DNA, and cGAS. Hence, aberrantly expressed ETS proteins derepress pericentromeric heterochromatin, yielding pathogenic RNAs that transmit genotoxic stress and inflammation to local and distant sites. Monitoring HSAT2,3 plasma levels and preventing their dissemination may thus improve therapeutic strategies and blood-based diagnostics.

miR-575/RIPK4 axis modulates cell cycle progression and proliferation by inactivating the Wnt/ß-catenin signaling pathway through inhibiting RUNX1 in colon cancer.

Receptor interacting protein serine/threonine kinase 4 (RIPK4) is widely involved in human cancer development. Nevertheless, its role in colon cancer (COAD) has not been elucidated till now. Our research aimed at exploring the function and underlying molecular mechanism of RIPK4 in COAD progression. Through bioinformatic analyses and RT-qPCR, RIPK4 was discovered to be increased in COAD cells and tissues, and its high level predicted poor prognosis. Loss-of-function assays revealed that RIPK4 silencing suppressed COAD cell growth, induced cell cycle arrest, and enhanced cell apoptosis. In vivo experiments also proved that tumor growth was inhibited by silencing of RIPK4. Luciferase reporter assay validated that RIPK4 was targeted and negatively regulated by miR-575. Western blotting demonstrated that Wnt3a, phosphorylated (p)-GSK-3ß, and cytoplasmic and nuclear ß-catenin protein levels, ß-catenin nuclear translocation, and Cyclin D1, CDK4, Cyclin E, and c-Myc protein levels were reduced by RIPK4 knockdown, which however was reversed by treatment with LiCl, the Wnt/ß-catenin pathway activator. LiCl also offset the influence of RIPK4 knockdown on COAD cell growth, cell cycle process, and apoptosis. Finally, RIPK4 downregulation reduced RUNX1 level, which was upregulated in COAD and its high level predicted poor prognosis. RIPK4 is positively associated with RUNX1 in COAD. Overexpressing RUNX1 antagonized the suppression of RIPK4 knockdown on RUNX1, Wnt3a, p-GSK-3ß, cytoplasmic ß-catenin, nuclear ß-catenin, Cyclin D1, CDK4, Cyclin E, and c-Myc levels. Collectively, miR-575/RIPK4 axis repressed COAD progression via inactivating the Wnt/ß-catenin pathway through downregulating RUNX1.

EV-mediated intercellular communication in acute myeloid leukemia: Transport of genetic materials in the bone marrow microenvironment.

Acute myeloid leukemia (AML) is a common hematological cancer. Cancer cells exchange information with the surrounding microenvironment, which can be transmitted by extracellular vesicles (EVs). In recent years, the genetic materials transported by EVs have attracted attention due to their important roles in different pathological processes. EV-derived ncRNAs (EV-ncRNAs) regulate physiological functions and maintain homeostasis, mainly including microRNAs, long noncoding RNAs, and circular RNAs. However, the mechanism of involvement and potential clinical application of EV-ncRNAs in AML have not been reported. Given the unique importance of the bone marrow microenvironment (BMME) for AML, a greater understanding of the communication between leukemic cells and the BMME is needed to improve the prognosis of patients and reduce the incidence of recurrence. Additionally, studies on leukemic EV-ncRNA transport guide the design of new diagnostic and therapeutic tools for AML. This review systematically describes intercellular communication in the BMME of AML and emphasizes the role of EVs. More importantly, we focus on the information transmission of EV-ncRNAs in the BMME to explore their clinical application as potential biomarkers and therapeutic targets.

Tumor-Educated Platelet RNA and Circulating Free RNA: Emerging Liquid Biopsy Markers for Different Tumor Types.

The incidence and mortality from malignant tumors continue to rise each year. Consequently, early diagnosis and intervention are vital for improving patient' prognosis and survival. The traditional pathological tissue biopsy is currently considered the gold standard for cancer diagnosis. However, it suffers from several limitations including invasiveness, sometimes not repeatable or unsuitable, and the inability to capture the dynamic nature of tumors in terms of space and time. Consequently, these limit the application of tissue biopsies for the diagnosis of early-stage tumors and have redirected the research focus towards liquid biopsies. Blood-based liquid biopsies have thus emerged as a promising option for non-invasive assessment of tumor-specific biomarkers. These minimally invasive, easily accessible, and reproducible tests offer several advantages, such as being mostly complication-free and efficient at monitoring tumor progression and tracing drug resistance. Liquid biopsies show great potential for cancer prediction, diagnosis, and prognostic assessment. Circulating tumor-educated platelets (TEPs) possess the unique ability to absorb nucleic acids from the bloodstream and to modify transcripts derived from megakaryocytes in response to external signals. In addition, circulating free RNA (cfRNA) constitutes a significant portion of the biomolecules present in the bloodstream. This paper aims to provide a comprehensive overview of the current research status regarding TEP RNA and cfRNA in liquid biopsies from various tumor types. Our analysis includes cancers of the lung, liver, pancreas, breast, nasopharynx, ovary and colon, as well as multiple myeloma and sarcoma. By synthesizing this information, we intend to establish a solid theoretical foundation for exploring potential applications of circulating RNA as a reliable biomarker for tumor diagnosis and monitoring.

Low RNA disruption during neoadjuvant chemotherapy predicts pathologic complete response absence in patients with breast cancer.

In previously reported retrospective studies, high tumor RNA disruption during neoadjuvant chemotherapy predicted for post-treatment pathologic complete response (pCR) and improved disease-free survival at definitive surgery for primary early breast cancer. The BREVITY (Breast Cancer Response Evaluation for Individualized Therapy) prospective clinical trial (NCT03524430) seeks to validate these prior findings. Here we report training set (Phase I) findings, including determination of RNA disruption index (RDI) cut points for outcome prediction in the subsequent validation set (Phase II; 454 patients). In 80 patients of the training set, maximum tumor RDI values for biopsies obtained during neoadjuvant chemotherapy were significantly higher in pCR responders than in patients without pCR post-treatment (P = .008). Moreover, maximum tumor RDI values ≤3.7 during treatment predicted for a lack of pCR at surgery (negative predictive value = 93.3%). These findings support the prospect that on-treatment tumor RNA disruption assessments may effectively predict post-surgery outcome, possibly permitting treatment optimization.

Liquid-based biomarkers in breast cancer: looking beyond the blood.

In recent decades, using circulating tumor cell (CTC), circulating tumor DNA (ctDNA), circulating tumor RNA (ctRNA), exosomes and etc. as liquid biomarkers has received enormous attention in various tumors, including breast cancer (BC). To date, efforts in the area of liquid biopsy predominantly focus on the analysis of blood-based markers. It is worth noting that the identifications of markers from non-blood sources provide unique advantages beyond the blood and these alternative sources may be of great significance in offering supplementary information in certain settings. Here, we outline the latest advances in the analysis of non-blood biomarkers, predominantly including urine, saliva, cerebrospinal fluid, pleural fluid, stool and etc. The unique advantages of such testings, their current limitations and the appropriate use of non-blood assays and blood assays in different settings are further discussed. Finally, we propose to highlight the challenges of these alternative assays from basic to clinical implementation and explore the areas where more investigations are warranted to elucidate its potential utility.

Exogenous Sequences in Tumors and Immune Cells (Exotic): A Tool for Estimating the Microbe Abundances in Tumor RNA-seq Data.

The microbiome affects cancer, from carcinogenesis to response to treatments. New evidence suggests that microbes are also present in many tumors, though the scope of how they affect tumor biology and clinical outcomes is in its early stages. A broad survey of tumor microbiome samples across several independent datasets is needed to identify robust correlations for follow-up testing. We created a tool called {exotic} for "exogenous sequences in tumors and immune cells" to carefully identify the tumor microbiome within RNA sequencing (RNA-seq) datasets. We applied it to samples collected through the Oncology Research Information Exchange Network (ORIEN) and The Cancer Genome Atlas. We showed how the processing removes contaminants and batch effects to yield microbe abundances consistent with non-high-throughput sequencing-based approaches and DNA-amplicon-based measurements of a subset of the same tumors. We sought to establish clinical relevance by correlating the microbe abundances with various clinical and tumor measurements, such as age and tumor hypoxia. This process leveraged the two datasets and raised up only the concordant (significant and in the same direction) associations. We observed associations with survival and clinical variables that are cancer specific and relatively few associations with immune composition. Finally, we explored potential mechanisms by which microbes and tumors may interact using a network-based approach. Alistipes, a common gut commensal, showed the highest network degree centrality and was associated with genes related to metabolism and inflammation. The {exotic} tool can support the discovery of microbes in tumors in a way that leverages the many existing and growing RNA-seq datasets. SIGNIFICANCE: The intrinsic tumor microbiome holds great potential for its ability to predict various aspects of cancer biology and as a target for rational manipulation. Here, we describe a tool to quantify microbes from within tumor RNA-seq and apply it to two independent datasets. We show new associations with clinical variables that justify biomarker uses and more experimentation into the mechanisms by which tumor microbiomes affect cancer outcomes.

Targeting nucleic acid sensors in tumor cells to reprogram biogenesis and RNA cargo of extracellular vesicles for T cell-mediated cancer immunotherapy.

Tumor-derived extracellular vesicles (EVs) have been associated with immune evasion and tumor progression. We show that the RNA-sensing receptor RIG-I within tumor cells governs biogenesis and immunomodulatory function of EVs. Cancer-intrinsic RIG-I activation releases EVs, which mediate dendritic cell maturation and T cell antitumor immunity, synergizing with immune checkpoint blockade. Intact RIG-I, autocrine interferon signaling, and the GTPase Rab27a in tumor cells are required for biogenesis of immunostimulatory EVs. Active intrinsic RIG-I signaling governs composition of the tumor EV RNA cargo including small non-coding stimulatory RNAs. High transcriptional activity of EV pathway genes and RIG-I in melanoma samples associate with prolonged patient survival and beneficial response to immunotherapy. EVs generated from human melanoma after RIG-I stimulation induce potent antigen-specific T cell responses. We thus define a molecular pathway that can be targeted in tumors to favorably alter EV immunomodulatory function. We propose "reprogramming" of tumor EVs as a personalized strategy for T cell-mediated cancer immunotherapy.

Touch imprint smear: A prerequisite to obtain better quality and "true" tumor RNA in breast tissues.

BACKGROUND: RNA is the primary genetic material required for various molecular studies. RNA derived from breast tissue has low quality and quantity compared to that extracted from other tissues. Therefore, optimization of techniques for breast tissue RNA extraction is a challenging but essential requirement. METHODS: RNA was extracted from 60 samples of breast cancer after dividing them into 2 groups. Each tissue was divided into 2 halves for RNA extraction and histopathology respectively. In group 2 RNA was extracted after taking touch imprints whereas group1 was not subjected to any such procedure. Concentration and purity of RNA was assessed by using spectrophotometer and 1% agarose gel followed by RT-PCR for 18 S rRNA and CCND1 gene. RESULTS: Based on microscopic observations of imprints, group 2 samples were further subdivided into 2 subgroups. Group 2 A (n = 30) showing tumor in imprint smears were found to yield best concentration of pure RNA (1846.50 ng/µl and 1.92) as compared to group 2B (n = 15) with no malignancy in imprints (102.61 ng/µl and 1.53). The correlation of imprint smears with their corresponding H&E-stained slides further leads to grouping of each group in 2 groups. RT-PCR analyses showed better melting peaks and high relative expression of CCND1 in group 2 A. CONCLUSION: Touch imprints may provide valuable information regarding presence or absence of tumor in tissue samples being used for extraction of genetic material. This approach can be used as easy, cheap and fast strategy to resolve the doubts associated with RNA being truly representative of the tumor.

RNA disruption is a widespread phenomenon associated with stress-induced cell death in tumour cells.

We have previously shown that neoadjuvant chemotherapy can induce the degradation of tumour ribosomal RNA (rRNA) in patients with advanced breast cancer, a phenomenon we termed "RNA disruption". Extensive tumour RNA disruption during chemotherapy was associated with a post-treatment pathological complete response and improved disease-free survival. The RNA disruption assay (RDA), which quantifies this phenomenon, is now being evaluated for its clinical utility in a large multinational clinical trial. However, it remains unclear if RNA disruption (i) is manifested across many tumour and non-tumour cell types, (ii) can occur in response to cell stress, and (iii) is associated with tumour cell death. In this study, we show that RNA disruption is induced by several mechanistically distinct chemotherapy agents and report that this phenomenon is observed in response to oxidative stress, endoplasmic reticulum (ER) stress, protein translation inhibition and nutrient/growth factor limitation. We further show that RNA disruption is dose- and time-dependent, and occurs in both tumourigenic and non-tumourigenic cell types. Northern blotting experiments suggest that the rRNA fragments generated during RNA disruption stem (at least in part) from the 28S rRNA. Moreover, we demonstrate that RNA disruption is reproducibly associated with three robust biomarkers of cell death: strongly reduced cell numbers, lost cell replicative capacity, and the generation of cells with a subG1 DNA content. Thus, our findings indicate that RNA disruption is a widespread phenomenon exhibited in mammalian cells under stress, and that high RNA disruption is associated with the onset of cell death.

Recent strategies for electrochemical sensing detection of miRNAs in lung cancer.

MicroRNAs (miRNAs) associated with lung cancer are diversifying. MiR-21, Let-7, and miR-141 are common diagnostic targets. Some new lung cancer miRNAs, such as miR-25, miR-145, and miR-126, have received increasing attention. Although various techniques are available for the analysis of lung cancer miRNAs, electrochemistry has been recognized for its high sensitivity, low cost, and rapid response. However, how to realize the signal amplification is one of the most important contents in the design of electrochemical biosensors. Herein, we mainly introduce the amplification strategy based on enzyme-free amplification and signal conversion, including non-linear HCR, catalytic hairpin assembly (CHA), electrochemiluminescence (ECL), and Faraday cage. Furthermore, new progress has emerged in the fields of nanomaterials, low oxidation potential, and simultaneous detection of multiple targets. Finally, we summarize some new challenges that electrochemical techniques may encounter in the future, such as improving single-base discrimination ability, shortening electrochemical detection time, and providing real body fluid samples assay.

Utilizing chemotherapy-induced tumor RNA nanoparticles to improve cancer chemoimmunotherapy.

Chemotherapy has become a popular combination strategy to improve the response rate of immunotherapy since certain chemotherapeutic drugs kill tumor cells by an immunogenic cell death (ICD) pathway, which activates antitumor immune responses. Unfortunately, the synergistic effect of chemoimmunotherapy can be impaired due to the toxicities of chemotherapeutic agent-induced lymphatic depletion and immunosuppression. In this study, we present an approach to improve immunotherapy by using tumor RNA nanoparticles (RNA-NPs) where RNA is directly extracted from chemotherapy-treated cancer cells and then condensed by protamine via electrostatic interactions to form complexes. Such RNA-NPs can be effectively taken up by dendritic cells (DCs) in the draining lymph nodes after subcutaneous injection. Compared with noninduced tumor RNA nanoparticles (N-RNA-NPs), chemotherapy-induced tumor RNA nanoparticles (C-RNA-NPs) can significantly promote DC maturation and stimulate a stronger immune response against established CT-26 colon carcinoma. Besides, C-RNA-NPs can improve the efficacy of immune checkpoint blockade (ICB) therapy by facilitating the infiltration of intratumoral T cells and increasing the ratio of CD8+ T cells to regulatory T cells (Tregs). More importantly, the synergistic effect of chemoimmunotherapy is also enhanced by treatment with C-RNA-NPs. STATEMENT OF SIGNIFICANCE: Although immune checkpoint blockade therapy has been demonstrated to be effective in some advanced cancers, the low response rate has significantly limited its clinical application. To address this issue, a new strategy for improving cancer immunotherapy using chemotherapy-induced tumor RNA nanoparticles (C-RNA-NPs) is developed in this work. The proposed C-RNA-NPs could be captured by dendritic cells, which were then stimulated to the maturation status to initiate an anticancer immune response. Furthermore, the response rate to immunotherapy was significantly increased by promoting intratumoral T-cell infiltration and elevating the intratumoral ratio of CD8+ T cells to regulatory T cells after treatment with C-RNA-NPs. Therefore, C-RNA-NPs have the potential to improve cancer immunotherapy.

Cromolyn chitosan nanoparticles reverse the DNA methylation of RASSF1A and p16 genes and mitigate DNMT1 and METTL3 expression in breast cancer cell line and tumor xenograft model in mice.

BACKGROUND: Developing epigenetic drugs for breast cancer (BC) remains a novel therapeutic approach. Cromolyn is a mast cell stabilizer emerging as an anticancer drug; its encapsulation in chitosan nanoparticles (CSNPs) improves its effect and bioavailability. However, its effect on DNA and RNA methylation machineries has not been previously tackled. METHODS: The possible anticancer effect of cromolyn CSNPs and its potential as an epigenetic drug was investigated in vitro using MCF-7 human BC cell line and in vivo using Ehrlich ascites carcinoma-xenograft model in mice symbolizing murine mammary adenocarcinoma. Mice were injected with a single dose of Ehrlich ascites carcinoma cells subcutaneously for the induction of tumor mass, and then randomized into three groups: control, cromolyn CSNPs (equivalent to 5 mg cromolyn/kg, i.p.) and plain CSNPs twice/week for 2 weeks. RESULTS: Cromolyn CSNPs showed prominent anticancer effect in MCF-7 cells by reducing the cell viability percent and enhancing DNA damage in the comet assay demonstrating its apoptotic actions. Mechanistically, cromolyn CSNPs influenced potential epigenetic processes through mitigating DNA methyltransferase 1 (DNMT1) expression, reversing the hypermethylation pattern of the tumor suppressor RASSF1A and p16 genes and attenuating the expression of the RNA N6-methyladenosine writer, methyltransferase-like 3 (METTL3). Cromolyn CSNPs diminished ERK1/2 phosphorylation, a possible arm influencing DNMT1 expression. In vivo, cromolyn CSNPs lessened the tumor volume and halted DNMT1 and METTL3 expression in Ehrlich carcinoma mice. CONCLUSIONS: Cromolyn CSNPs have the premise as an epigenetic drug through inhibiting ERK1/2 phosphorylation/DNMT1/DNA methylation and possibly impacting the RNA methylation machinery via mitigating METTL3 expression.