miR-30b-5p acts as a tumor suppressor microRNA in esophageal squamous cell carcinoma

Background: To study miR-30b-5p expression in esophageal squamous cell carcinoma (ESCC) by comparisons between tumor tissues and matched adjacent non-cancerous tissues to elucidate the correlation between miR-30b-5p expression and ESCC clinical parameters, and to explore the signaling pathways associated with miR-30b-5p and key target genes. Methods: Clinical data, cancer tissues, and adjacent non-cancerous tissues of 32 patients diagnosed with ESCC were collected from Taizhou Hospital of Zhejiang Province. The expression levels of miR-30b-5p were determined by real-time polymerase chain reaction (RT-PCR). mRNA data for ESCC tissues and normal tissues, and clinical materials of patients with ESCC were obtained from the Gene Expression Omnibus (GEO) database and The Cancer Genome Atlas (TCGA). Associations between miR-30b-5p expression and clinical features of patients with ESCC and overall survival were explored. A bioinformatics analysis was performed to determine the pathways and key miR-30b-5p targets associated with ESCC. Additionally, a cytological experiment was performed to evaluate the biological functions of miR-30b-5p. Finally, correlations between miR-30b-5p and key targets involved in PI3K/Akt signaling pathways were validated by western blotting. Results: The expression level of miR-30b-5p in the 32 ESCC tissues was significantly lower than that in adjacent normal tissues (P< 0.01) and was significantly disparate in the T stage, with higher expression in T1 than in T2 (P< 0.05). Among the patients with higher expression levels of miR-30b-5p in ESCC tissues than in adjacent normal tissues, patients with higher expression of miR-30b-5p had a better prognosis (P< 0.05). An analysis of gene chip data from the GEO database showed similar results. A gene enrichment analysis indicated a series of pathways that may be associated with the downregulation of miR-30b-5p, including focal adhesion, ECM-receptor interaction, and PI3K/Akt signaling pathways. Seven key target genes (PDGFRB, VIM, ITGA5, ACTN1, THBS2, SERPINE1, and RUNX2) were identified; these were found to be upregulated in ESCC tissues and were negatively correlated with miR-30b-5p. Functional experiments showed that miR-30b-5p attenuated migration (P< 0.01) and invasion (P< 0.05) in the Eca109 cell line. Moreover, the levels of ITGA5, PDGFRB, p-PI3K, and p-AKT, which are involved in the PI3K/Akt signaling pathway, were decreased in the miR-30b-5p-overexpressing Eca109 cell line. Conclusions: Upregulated miR-30b-5p may inhibit migration and invasion in ESCC by targeting ITGA5, PDGFRB, and signaling pathways, such as PI3K/Akt, involved in ESCC regulation. Our results indicate that miR-30b-5p plays an important role in the occurrence and progression of ESCC and is a potential therapeutic target.