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MIR21

MIR21

Overview

MIR21 encodes microRNA-21 (miR-21), a small non-coding RNA that functions as a post-transcriptional regulator of gene expression. Like other microRNAs, it acts by binding target messenger RNAs and modulating their stability or translation, thereby influencing cellular programs such as proliferation, apoptosis, and stress responses. In biomedical research, miR-21 is widely studied as a cancer-associated biomarker and regulatory molecule, particularly in breast cancer and other solid tumors.

Recent studies have continued to use MIR21 as a model target for both mechanistic cancer research and ultrasensitive molecular detection. In these contexts, miR-21 is frequently discussed alongside breast cancer, triple-negative breast adenocarcinoma, colorectal, head/neck, melanoma, and prostate tumors, reflecting its broad relevance in oncology. It has also been investigated in relation to pathways and molecular factors such as PTEN and the SIRT1/HIF-1α pathway, consistent with its role in tumor biology and treatment response.

Focus of Latest Publications

Recent publications have focused heavily on MIR21 as a biomarker and functional target in cancer diagnostics and therapeutic modulation. Several studies developed highly sensitive detection platforms for miR-21, including CRISPR/Cas12a-based assays, electrochemical biosensors, DNA nanodevices, and exosome-based quantification methods. These approaches were designed for rapid, low-instrument, and often amplification-free or reverse-transcription-free detection, with reported applications in bladder cancer, hepatocellular carcinoma, triple-negative breast cancer, and breast cancer-derived exosomes. Across these studies, miR-21 was repeatedly paired with other biomarkers such as miR-96, miR-122, miR-210, and miR-27a to improve diagnostic discrimination and molecular subtyping.

In bladder cancer, miR-21 was used as a target in a dual-channel quantum dot DNA nanosphere assay that enabled simultaneous profiling of urinary miR-21 and miR-96 within 40 minutes, with attomolar sensitivity and strong concordance with qPCR in clinical urine samples. The integrated dual-miRNA analysis improved diagnostic performance for distinguishing bladder cancer from healthy controls and other urological diseases. Another bladder-cancer-focused study reported CRISPR/Cas9-mediated miR-21 editing in high-grade urothelial carcinoma cells, indicating interest in directly manipulating miR-21 in tumor biology, although the abstract provided does not detail the biological outcomes.

Therapeutic and mechanistic studies also linked MIR21 modulation to cancer cell behavior. In triple-negative breast cancer cells, betulinic acid, alone or combined with doxorubicin, was associated with downregulation of miR-21, increased apoptosis, reduced HIF1A and SMAD7 expression, and increased PDCD4 and PTEN expression. Molecular docking suggested potential interactions of betulinic acid and doxorubicin with PTEN and PDCD4. In another breast-cancer-related study, miR-21 served as one of the biomarkers driving a dichromatically encoded DNA nanodevice for high-resolution subtyping of triple-negative breast cancer, where co-detection with APE1 activity and miR-210 enabled subtype discrimination.

Beyond cancer, miR-21 was also examined in a diabetic kidney disease context, where salvianolic acid C was reported as a pyroptosis inhibitor acting through the miRNA-21/A20 pathway in podocyte injury, although the abstract provides only the study aim and not the detailed results. Overall, the recent literature portrays MIR21 as both a clinically useful biomarker and a mechanistic node that is being targeted for detection, cancer stratification, and pathway modulation across multiple disease settings.

Key Publications

  • NEWJun CRISPR/Cas9-mediated miR-21 editing in high-grade urothelial carcinoma cells and its biological effects. (Molecular biology reports, 2026, PMID 42319574): "At the molecular level, microRNA-21 (miR-21) has been characterized as an "oncomir" because of its ability to negatively regulate tumor suppressor genes, thereby promoting tumor survival and progression."
  • NEWJun Dual MicroRNA Simultaneous One-Step Profiling via Filler-Mediated Quantum Dot DNA Nanospheres for Bladder Cancer Screening. (ACS nano, 2026, PMID 42287261): "for simultaneous detection of miRNA-21 and miRNA-96."
  • NEWJun Modular CRISPR-Cas12a-Activated Gold Nanoparticle Assay for Rapid Visual Detection of Hepatocellular Carcinoma-Related miRNAs. (ACS sensors, 2026, PMID 42263201): "Using miRNA-21 and miRNA-122 as targets, mC-NCA shows calculated limits of detection (LODs) of 1.62 and 1.64 fM with a linear range of 50 fM-500 pM, whereas mC-vLFA shows calculated LODs of 1.59 and 1.40 fM with a linear range of 10 fM-10 nM."
  • May Betulinic acid is associated with miR-21 modulation, apoptosis and redox changes in breast cancer cells: an in vitro and in silico study. (Scientific reports, 2026, PMID 42143107): "The current study aimed to explore the anticancer potential effect, molecular targets, and association with miR-21 modulation after BA treatment and its combination with doxorubicin against human triple-negative breast cancer (MDA-MB-231) cells."
  • May A unified computational-experimental paradigm for rational design of next-generation electrochemical biosensors: the IECM framework. (Biomedical physics & engineering express, 2026, PMID 42119575): "yielding exceptionally low values of 0.12 fg ml-1 for prostate-specific antigen and 5.0 × 10-18M for microRNA-21, with corresponding calibration curve slopes confirming high signal-to-noise ratios."
  • May Dichromatically Encoded DNA Nanodevice for High-Resolution Molecular Subtyping of Triple-Negative Breast Cancer. (Analytical chemistry, 2026, PMID 42071303): "In the presence of APE1 and miRNA-21 (which are widely recognized as breast cancer biomarkers), the orthogonal recognition initiates a catalytic hairpin assembly (CHA) reaction that links a single DRIVE into a linear DNA nanostructure, thus significantly amplifying a monochromatic FAM signal."
  • Mar Salvianolic acid C, a novel pyroptosis inhibitor, attenuates podocyte injury in diabetic kidney disease through regulating miRNA-21/A20 pathway. (Journal of ethnopharmacology, 2026, PMID 41903586): "...through regulating miRNA-21/A20 pathway."
  • Jun Ultrasensitive miRNA detection via magnetic bead-confined catalytic hairpin assembly enabling transcription-driven crRNA assembly and CRISPR/Cas12a activation. (Biosensors & bioelectronics, 2026, PMID 41747377): "We demonstrated that the biosensor exhibits exceptional sensitivity for miRNA-21 detection, achieving a limit of 65.3 aM."
  • May Competitive magneto enzyme-linked miRNA assay for quantification of microRNAs in exosomes. (Talanta, 2026, PMID 41605075): "As proof of concept, miRNA-21 and miRNA-27a, both upregulated in breast cancer, were quantified in MCF-7 and MDA-MB-231 cells and their derived exosomes."
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