MicroRNA (miRNA) dysregulation plays a critical role in cancer development, progression, and therapy response. miRNAs are small non-coding RNA molecules that regulate gene expression by targeting messenger RNAs. They are involved in various biological processes, including cell differentiation, proliferation, and survival. Dysregulation of miRNAs can lead to oncogenic or oncosuppressive effects, making them important diagnostic, prognostic, and therapeutic targets in cancer. miRNAs are transcribed by RNA polymerase II and processed through a series of enzymatic steps involving Drosha and Dicer. The mature miRNA is then incorporated into the RNA-induced silencing complex (RISC), where it guides the degradation or inhibition of target mRNAs. miRNAs can also act as oncogenes or oncosuppressors by targeting specific genes involved in cancer pathways. In cancer, miRNA dysregulation is associated with altered gene expression, tumor progression, and response to therapy. miRNAs have been identified as potential biomarkers for cancer diagnosis, prognosis, and treatment response. For example, miR-15a and miR-16-1 are frequently deleted in chronic lymphocytic leukemia (CLL), and their loss is linked to poor prognosis. miRNA profiling has shown promise in distinguishing cancer subtypes and identifying the tissue of origin of tumors. miRNAs are also involved in regulating the response to therapies. For instance, miR-21 is overexpressed in various cancers and is associated with poor prognosis and resistance to treatment. Conversely, miR-29 family members can suppress oncogenic activity by targeting genes involved in cell proliferation and survival. The dysregulation of miRNAs can occur through genetic abnormalities, epigenetic modifications, or defects in miRNA biogenesis. Epigenetic changes, such as DNA methylation, can alter miRNA expression and contribute to cancer development. miRNAs can also regulate the expression of components of the epigenetic machinery, creating a feedback loop that influences cancer progression. As therapeutic targets, miRNAs can be modulated using antisense oligonucleotides or viral vectors to restore normal miRNA function. For example, miR-15a/16-1 can induce apoptosis in leukemia cells, while miR-21 inhibition can enhance the response to chemotherapy. However, challenges remain in delivering miRNAs effectively to target tissues and ensuring their stability. In summary, miRNAs are important regulators of cancer biology and have significant potential as diagnostic, prognostic, and therapeutic tools. Further research is needed to fully understand their role in cancer and to develop effective miRNA-based therapies.MicroRNA (miRNA) dysregulation plays a critical role in cancer development, progression, and therapy response. miRNAs are small non-coding RNA molecules that regulate gene expression by targeting messenger RNAs. They are involved in various biological processes, including cell differentiation, proliferation, and survival. Dysregulation of miRNAs can lead to oncogenic or oncosuppressive effects, making them important diagnostic, prognostic, and therapeutic targets in cancer. miRNAs are transcribed by RNA polymerase II and processed through a series of enzymatic steps involving Drosha and Dicer. The mature miRNA is then incorporated into the RNA-induced silencing complex (RISC), where it guides the degradation or inhibition of target mRNAs. miRNAs can also act as oncogenes or oncosuppressors by targeting specific genes involved in cancer pathways. In cancer, miRNA dysregulation is associated with altered gene expression, tumor progression, and response to therapy. miRNAs have been identified as potential biomarkers for cancer diagnosis, prognosis, and treatment response. For example, miR-15a and miR-16-1 are frequently deleted in chronic lymphocytic leukemia (CLL), and their loss is linked to poor prognosis. miRNA profiling has shown promise in distinguishing cancer subtypes and identifying the tissue of origin of tumors. miRNAs are also involved in regulating the response to therapies. For instance, miR-21 is overexpressed in various cancers and is associated with poor prognosis and resistance to treatment. Conversely, miR-29 family members can suppress oncogenic activity by targeting genes involved in cell proliferation and survival. The dysregulation of miRNAs can occur through genetic abnormalities, epigenetic modifications, or defects in miRNA biogenesis. Epigenetic changes, such as DNA methylation, can alter miRNA expression and contribute to cancer development. miRNAs can also regulate the expression of components of the epigenetic machinery, creating a feedback loop that influences cancer progression. As therapeutic targets, miRNAs can be modulated using antisense oligonucleotides or viral vectors to restore normal miRNA function. For example, miR-15a/16-1 can induce apoptosis in leukemia cells, while miR-21 inhibition can enhance the response to chemotherapy. However, challenges remain in delivering miRNAs effectively to target tissues and ensuring their stability. In summary, miRNAs are important regulators of cancer biology and have significant potential as diagnostic, prognostic, and therapeutic tools. Further research is needed to fully understand their role in cancer and to develop effective miRNA-based therapies.