Objective
This study aimed to elucidate the regulatory role of c-Myc-associated miR-196a-5p in the progression of triple-negative breast cancer (TNBC). We further explored its target genes to investigate possible mechanisms of action.
Methods
High-throughput sequencing was employed to profile microRNA expression in MDA-MB-231 cells with differential c-Myc expression. Differentially expressed microRNAs were identified, and miR-196a-5p levels, along with the expression of predicted target genes, were quantified using quantitative reverse transcription polymerase chain reaction (qRT-PCR) in c-Myc knockdown cells. Candidate targets were predicted using miRDB and TargetScan databases and further validated by qRT-PCR and Western blotting in MDA-MB-231 and MDA-MB-468 cells with modulated miR-196a-5p expression. Functional assays, including clonogenic assays, flow cytometry, and Transwell migration and invasion assays were conducted to evaluate the effects of miR-196a-5p on cellular behavior.
Results
miR-196a-5p expression was significantly reduced in c-Myc-deficient cells and exhibited a positive association with c-Myc levels. Bioinformatic analysis identified HOXA7 and HOXB7 as miR-196a-5p putative targets, with inverse expression patterns observed between the microRNA and these genes. Downregulation of miR-196a-5p resulted in elevated expression of HOXA7 and HOXB7, whereas its overexpression resulted in their suppression. Functionally, increased levels of miR-196a-5p were associated with enhanced proliferation, invasion, and migration, along with decreased apoptosis in TNBC cells.
Conclusion
Our findings reveal a positive correlation between c-Myc and miR-196a-5p in TNBC, suggesting that miR-196a-5p may promote tumor progression by regulating cellular proliferation, invasion, migration, and apoptosis. The inverse expression patterns between miR-196a-5p and HOXA7/HOXB7 imply these genes may be downstream targets, though direct causal relationships and detailed molecular mechanisms require further validation.
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