Objective: To explore the roles of micro ribonucleic acid (miR)-199a-5p in the proliferation, apoptosis, invasion and metastasis of laryngeal cancer cells, and its molecular mechanisms.
Patients and methods: The expression of miR-199a-5p in 25 cases of laryngeal cancer tissues and paracancerous tissues was detected via quantitative real-time polymerase chain reaction (qRT-PCR). Its expression in TU212, TU686 and human epithelial type 2 (HEp-2) laryngeal cancer cell lines and normal nasopharyngeal epithelial cell line NP69 was also detected via qRT-PCR. HEp-2 cells were transiently transfected with miR-199a-5p mimic or miR-199a-5p inhibitor, and the expression of miR-199a-5p was verified using RT-PCR after transfection. The regulatory effects of miR-199a-5p on the proliferation, apoptosis, invasion and migration abilities of HEp-2 cells were observed through methyl thiazolyl tetrazolium (MTT) assay, flow cytometry, wound healing assay and transwell assay, respectively. Then, the mechanisms of miR-199a-5p in regulating Caspase-3 activity and epithelial-mesenchymal transition (EMT)-related proteins were further explored.
Results: The qRT-PCR results revealed that miR-199a-5p was significantly lowly expressed in the laryngeal cancer tissues and tumor cell lines, and overexpression of miR-199a-5p substantially inhibited the proliferation of HEp-2 cells. According to the results of flow cytometry, overexpression of miR-199a-5p promoted the apoptosis of HEp-2 cells, whereas down-regulating miR-199a-5p suppressed their apoptosis. It was found that the activity of Caspase-3 was notably enhanced after overexpression of miR-199a-5p, which was evidently weakened after down-regulating miR-199a-5p. Wound healing assay and transwell assay results manifested that overexpressing miR-199a-5p weakened the invasion and migration abilities of HEp-2 cells, which were facilitated by down-regulating miR-199a-5p. Based on Western blotting results, miR-199a-5p regulated the expressions of E-cadherin, N-cadherin and vimentin. Overexpression of miR-199a-5p could inhibit EMT process, whereas suppressing miR-199a-5p could accelerate the process.
Conclusions: The expression of miR-199a-5p in laryngeal cancer tissues is substantially lower than that in the paracancerous tissues. MiR-199a-5p suppresses proliferation, invasion and migration in laryngeal cancer cell proliferation, while triggers cell apoptosis.