Worldwide, breast cancer is the most frequent cancer in women. Current research reveals that lncRNA/miRNA/mRNA axes are involved in several cancers. The lncRNA NEAT1 sponging of miR-20b-5p and STAT3 regulation by miR-20b-5p have previously been established. The clinicopathological relationship between NEAT1 and the miR-20b-5p/STAT3 axis in breast cancers is unknown. This study aims to investigate the clinicopathological associations and significance of NEAT1/miR-20b-5p/STAT3 axes in breast cancer. qRT-PCR and immunohistochemistry were performed on archived formalin-fixed paraffin-embedded breast tumor tissues (n = 79) and adjacent normal tissues (n = 40). Receiver operating characteristic (ROC) curve analysis examined NEAT1 and miR-20b-5p diagnostic value. The qRT-PCR revealed significantly higher total NEAT1 and NEAT1_2 isoform levels in breast tumors compared to normal tissues with significant associations with ER, PR statuses, age, stages, and lymph node metastasis (p < 0.05). Methylation-specific PCR of DNA showed that normal and tumor samples had distinct NEAT1 promoter methylation (p < 0.05). Immunohistochemistry showed that tumors and normal tissues have differing STAT3 protein expression, and significantly correlated with NEAT1 levels (p < 0.05). Bioinformatics analysis predicted STAT3 targeting hsa-miR-20b-5p and substantial NEAT1_2 isoform interaction with hsa-miR-20b-5p. qRT-PCR revealed low levels of hsa-miR-20b-5p and an inverse correlation with NEAT1 and NEAT1_2 levels in tumors (p < 0.05). NEAT1 and miR-20b-5p have diagnostic values according to ROC curves. Knockdown of NEAT1 in MCF7 cells by siRNA increased hsa-miR-20b-5p levels and decreased STAT3 mRNA. CCND1 expression correlated with the expression of its transcriptional activator STAT3 in MCF7 cells and tumor tissues. Overall, the study suggests NEAT1/hsa-miR-20b-5p/STAT3 axes as a potential biomarker in breast tumors.
Keywords: Breast cancer; Hsa-miR-20b-5p; NEAT1; NEAT1_2; STAT3.
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