Silencing the lncRNA NORAD inhibits EMT of head and neck squamous cell carcinoma stem cells via miR‑26a‑5p

Cancer stem cells are closely associated with tumor metastasis or recurrence. According to previous literature reports, microRNA (miR)‑26a has an inhibitory effect on head and neck squamous cell carcinoma (HNSCC), and the long non‑coding RNA (lncRNA) non‑coding RNA activated by DNA damage (NORAD) has been found to interact with miR‑26a‑5p. The present study aimed to investigate the regulation and mechanism of NORAD and miR‑26a‑5p in the epithelial‑mesenchymal transition (EMT) of HNSCC stem cells. An ALDEFLUOR stem cell detection kit, a flow cytometer, a self‑renewal ability test and western blotting were used to sort and identify HNSCC stem cells. The ENCORI website and a dual‑luciferase assay were used to assess the relationship between genes. The mRNA and protein expression levels of NORAD, miR‑26a‑5p and EMT‑related genes were detected via reverse transcription‑quantitative PCR and western blotting. Functional experiments (MTT assay, flow cytometry, wound healing assay and Transwell assay) were conducted to analyze the effects of NORAD and miR‑26a‑5p on HNSCC stem cells. The successfully sorted aldehyde dehydrogenase (ALDH)⁺ cells had a self‑renewal capacity and displayed upregulated expression levels of CD44, Oct‑4 and Nanog. NORAD knockdown, achieved using small interfering (si)RNA, downregulated the expression levels of tumor markers in ALDH⁺ cells. siNORAD inhibited cell vitality, migration and invasion, as well as promoted apoptosis, increased the expression of epithelial cell markers and decreased the expression of interstitial cell markers in HNSCC stem cells. miR‑26a‑5p was a downstream gene of NORAD, and knockdown of miR‑26a‑5p partially offset the regulatory effect of siNORAD on HNSCC stem cells. Collectively, the present study demonstrated that NORAD knockdown attenuated the migration, invasion and EMT of HNSCC stem cells via miR‑26a‑5p.

miR‑26a‑5p alleviates lipopolysaccharide‑induced acute lung injury by targeting the connective tissue growth factor

The aim of the present study was to investigate the regulatory functions of microRNA (miR)‑26a‑5p on lipopolysaccharide (LPS)‑induced acute lung injury (ALI) and its molecular mechanisms. The role of miR‑26a‑5p on an ALI mouse model was evaluated by examining the histological changes, wet/dry (W/D) ratio, myeloperoxidase (MPO) activity, malondialdehyde (MDA) expression levels in lung tissues and the survival of ALI mice. Moreover, the protein concentration and the number of neutrophils and lymphocytes in bronchoalveolar lavage fluid (BALF) was analyzed. To explore the effect of miR‑26a‑5p on inflammatory responses and apoptosis, the expression levels of tumour necrosis factor‑α (TNF‑α), interleukin (IL)‑1β and IL‑6 and apoptosis were measured by ELISA, terminal deoxynucleotidyl transferase‑mediated dUTP nick end labelling staining and flow cytometry in BALF, A549 cells and lung tissues. B‑cell lymphoma‑2 (Bcl‑2), Bax and cleaved caspase‑3 in lung tissues were measured by western blotting and reverse transcription‑quantitative PCR. Connective tissue growth factor (CTGF) was predicted as a direct target of miR‑26a‑5p using dual luciferase reporter assay. The present study sought to determine whether CTGF overexpression reversed the effect of miR‑26a‑5p on apoptosis and inflammatory responses in LPS‑induced A549 cells. The data revealed that miR‑26a‑5p overexpression ameliorated LPS‑induced ALI, which was implicated by fewer histopathological changes, W/D ratio, apoptosis in lung tissues and the survival of ALI mice. Moreover, miR‑26a‑5p overexpression alleviated LPS‑induced inflammatory responses in ALI mice via the reduction of total protein, neutrophil and lymphocyte counts and the expression levels of TNF‑α, IL‑1β, IL‑6, MDA and MPO activity in BALF. Similarly, miR‑26a‑5p overexpression decreased apoptosis and the expression of TNF‑α, IL‑1β and IL‑6 in LPS‑induced A549 cells. CTGF was a direct target of miR‑26a‑5p. CTGF overexpression reversed the effect of miR‑26a‑5p on cell apoptosis and inflammatory responses in LPS‑induced A549 cells. The present study demonstrated that miR‑26a‑5p could attenuate lung inflammation and apoptosis in LPS‑induced ALI by targeting CTGF.