FENDRR Affects COAD Biological Behavior by Inhibiting the DUSP4/CREB/PRKACB Pathway

<b>Background:</b> Colorectal cancer (CRC) is acknowledged as the third leading cause of cancer-related mortality, attributed to its high incidence and fatality rates. Long noncoding RNAs (lncRNAs) have emerged as novel biomarkers for the treatment of colon adenocarcinoma. This study is aimed at investigating the function and underlying mechanisms of the lncRNA fetal-lethal noncoding developmental regulatory RNA (FENDRR) in regulating the malignant phenotype of CRC (COAD) cells. <b>Methods:</b> This investigation examined FENDRR expression patterns and their association with clinical outcomes in 496 COAD and 173 READ patients from The Cancer Genome Atlas (TCGA) dataset. Additionally, 10 clinical COAD specimens were collected to validate FENDRR expression levels. Using lentiviral-mediated gene delivery, we stably upregulated FENDRR in HCT-116 cells, with transcriptional changes quantified via qPCR. The tumor biological behavior was evaluated using in vitro experiments, including CCK-8, colony formation, wound healing, transwell assays, and immunofluorescence staining. Protein-level alterations were subsequently confirmed by Western blot. <b>Results:</b> Through bioinformatics evaluation, a notable decrease in FENDRR expression levels was observed in both COAD and READ tissues, with a pronounced link between FENDRR expression and tumor T stage classification in COAD cases. Patients exhibiting diminished FENDRR expression showed worse clinical outcomes in COAD. Enrichment analysis demonstrated significant associations between FENDRR and various signaling cascades, particularly the cAMP pathway. Additionally, immune cell infiltration analysis showed a significant association with FENDRR expression levels. In vitro experiments confirmed that FENDRR overexpression hindered the proliferation, migration, and invasion of cells. Mechanistically, FENDRR has been demonstrated to induce the sinking of the DUSP4/CREB/PRKACB signaling pathway and reverse the epithelial-mesenchymal transition (EMT) pathway, thereby inhibiting tumor growth. <b>Conclusion:</b> We establish FENDRR as a tumor-suppressing gene that plays a significant role in suppressing the advancement and metastatic spread of COAD. These findings underscore its diagnostic and prognostic utility in COAD.