MicroRNAs (miRNAs) are small non-coding regulatory RNAs that regulate gene expression post-transcriptionally by binding to complementary sites in the 3' untranslated region (UTR) of target mRNAs. Over the past decade, miRNAs have been identified as key regulators in various biological processes, including cancer. miRNA expression profiling has revealed their roles in cancer diagnosis, prognosis, and therapy. miRNAs are involved in multiple aspects of cancer biology, such as proliferation, apoptosis, invasion, metastasis, and angiogenesis. Many miRNAs are deregulated in cancers, and their altered expression is associated with cancer progression. miRNAs can act as oncogenes or tumor suppressors, and their dysregulation contributes to tumorigenesis. The mechanisms of miRNA deregulation in cancers include genomic abnormalities, epigenetic factors, transcriptional regulation, and processing steps. Aberrant miRNA expression can lead to changes in the miRNome, which may influence cancer development. miRNAs can also be involved in cancer progression through various mechanisms, such as direct targeting of oncogenes or tumor suppressor genes, or through altered miRNA target sites. Viruses can also influence cancer by expressing viral oncogenes or miRNAs that regulate cellular processes. miRNAs have been implicated in various cancer types, including lymphomas, lung cancers, and colorectal cancers. miRNAs such as miR-17-92, miR-21, miR-155, and let-7 have been shown to play oncogenic or tumor suppressive roles. miRNAs are also being explored as potential therapeutic targets, with strategies such as miRNA mimics and inhibitors being developed. miRNAs may also be used as diagnostic tools due to their stability and ability to reflect tumor origin and stage. However, further research is needed to fully understand the role of miRNAs in cancer and to develop effective therapeutic strategies.MicroRNAs (miRNAs) are small non-coding regulatory RNAs that regulate gene expression post-transcriptionally by binding to complementary sites in the 3' untranslated region (UTR) of target mRNAs. Over the past decade, miRNAs have been identified as key regulators in various biological processes, including cancer. miRNA expression profiling has revealed their roles in cancer diagnosis, prognosis, and therapy. miRNAs are involved in multiple aspects of cancer biology, such as proliferation, apoptosis, invasion, metastasis, and angiogenesis. Many miRNAs are deregulated in cancers, and their altered expression is associated with cancer progression. miRNAs can act as oncogenes or tumor suppressors, and their dysregulation contributes to tumorigenesis. The mechanisms of miRNA deregulation in cancers include genomic abnormalities, epigenetic factors, transcriptional regulation, and processing steps. Aberrant miRNA expression can lead to changes in the miRNome, which may influence cancer development. miRNAs can also be involved in cancer progression through various mechanisms, such as direct targeting of oncogenes or tumor suppressor genes, or through altered miRNA target sites. Viruses can also influence cancer by expressing viral oncogenes or miRNAs that regulate cellular processes. miRNAs have been implicated in various cancer types, including lymphomas, lung cancers, and colorectal cancers. miRNAs such as miR-17-92, miR-21, miR-155, and let-7 have been shown to play oncogenic or tumor suppressive roles. miRNAs are also being explored as potential therapeutic targets, with strategies such as miRNA mimics and inhibitors being developed. miRNAs may also be used as diagnostic tools due to their stability and ability to reflect tumor origin and stage. However, further research is needed to fully understand the role of miRNAs in cancer and to develop effective therapeutic strategies.