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<article xsi:noNamespaceSchemaLocation="http://jats.nlm.nih.gov/publishing/1.1/xsd/JATS-journalpublishing1-mathml3.xsd" dtd-version="1.1" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><front><journal-meta><journal-id journal-id-type="publisher-id">PAR</journal-id><journal-title-group><journal-title>Proceedings of Anticancer Research</journal-title></journal-title-group><issn>2208-3545</issn><eissn>2208-3553</eissn><publisher><publisher-name>Bio-Byword Scientific Publishing Pty. Ltd.</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.26689/par.v8i6.8160</article-id><article-categories><subj-group subj-group-type="heading"><subject>Article</subject></subj-group></article-categories><title>New Insights on the Roles of miR-21 in Cancer Development and Proliferation</title><url>https://artdesignp.com/journal/PAR/8/6/10.26689/par.v8i6.8160</url><author>HayatAhmad</author><pub-date pub-type="publication-year"><year>2024</year></pub-date><volume>8</volume><issue>6</issue><history><date date-type="pub"><published-time>2024-11-22</published-time></date></history><abstract>MicroRNAs (miRNAs) are small noncoding RNAs strongly implicated in the control of gene expression post-transcriptionally. They account for a wide range of functions recognized as characteristic cancer signatures, including apoptosis, invasion, metastasis, and proliferation. MicroRNA-21 (miR-21) is well-recognized for its crucial role in various solid tumors, such as glioblastoma, ovarian cancer, non-small cell lung cancer, and many others. In numerous malignancies, miR-21 selectively targets multiple key components and influences a broad spectrum of cellular processes, including cancer stemness and cell death. The miR-21 gene exhibits both cancer-promoting and cancer-suppressing properties, though most research highlights its facilitative role in cancer development. MiR-21 mediates PTEN reduction to enhance PI3K/Akt signaling in cancer progression. Its overexpression inhibits apoptosis and significantly promotes pro-survival autophagy. The notable upregulation of miR-21 in cancerous tissues positions it as a promising cancer biomarker with considerable diagnostic and prognostic potential. 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