Cancer Genetics and Epigenetics 2024, Vol.12, No.6, 358-367 http://medscipublisher.com/index.php/cge 359 This study aims to elucidate the complex regulatory networks involving lncRNAs and miRNAs in colon cancer and to identify promising avenues for future research and clinical intervention. Figure 1 Regulatory Roles of lncRNAs and miRNAs in Colon Cancer Progression 2 Biology of lncRNAs and miRNAs 2.1 Definition and classification 2.1.1 Long non-coding RNAs (lncRNAs) Long non-coding RNAs (lncRNAs) are a diverse class of RNA molecules longer than 200 nucleotides that do not encode proteins. They are involved in various cellular processes, including chromatin modification, transcriptional regulation, and post-transcriptional regulation. LncRNAs can act as molecular scaffolds, guides, decoys, or sponges, influencing gene expression by interacting with DNA, RNA, and proteins (Chen et al., 2018; Tang et al., 2019; Volovat et al., 2020). 2.1.2 MicroRNAs (miRNAs) MicroRNAs (miRNAs) are small, non-coding RNA molecules, typically 19-25 nucleotides in length, that regulate gene expression post-transcriptionally. They primarily function by binding to the 3′ untranslated regions (3′ UTR) of target mRNAs, leading to mRNA degradation or translational repression. MiRNAs are highly conserved across species and play crucial roles in various biological processes, including development, differentiation, proliferation, and apoptosis (O'Brien et al., 2018; Tam et al., 2019; Annese et al., 2020). 2.2 Biogenesis and mechanisms of action 2.2.1 lncRNA biogenesis LncRNAs are transcribed by RNA polymerase II and undergo similar processing steps as mRNAs, including capping, splicing, and polyadenylation. However, their biogenesis is less understood compared to miRNAs. LncRNAs can originate from various genomic regions, including intergenic, intronic, and antisense regions. They can regulate gene expression at multiple levels, including chromatin remodeling, transcriptional control, and post-transcriptional processing (Chen et al., 2018; Tang et al., 2019; Volovat et al., 2020). MiRNA biogenesis begins with the transcription of primary miRNAs (pri-miRNAs) by RNA polymerase II. These pri-miRNAs are processed in the nucleus by the Drosha-DGCR8 complex into precursor miRNAs (pre-miRNAs). The pre-miRNAs are then exported to the cytoplasm, where they are further processed by Dicer into mature miRNAs. The mature miRNAs are incorporated into the RNA-induced silencing complex (RISC), which guides them to their target mRNAs to mediate gene silencing through mRNA degradation or translational repression (O'Brien et al., 2018; Annese et al., 2020; Dexheimer and Cochella, 2020).
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