Effect of MiR-32 on gastric carcinoma tumorigenesis by targeting Kruppel-like factor 4.

Abstract

76 Background: Gastric cancer (GC) is a prevalent malignant cancer worldwide and is highly lethal because of its fast growth. Currently, the comprehensive treatment is the combination of surgery, chemotherapy and radiotherapy, which has made progress in the treatment of advanced GC. However, the accuracy of current diagnostic methods is not very satisfactory. To address these limitations and improve the survival rate and reduce mortality it is necessary to identify sensitive early diagnostic markers. MiR-32 has been reported as an oncogenic microRNA in many cancers, but its role in GC is unclear. Methods: We detected miR-32 expression in clinical gastric carcinoma tissue samples and adjacent normal tissue samples from the same patient. The expression of miR-32 was also detected in 40 gastric carcinoma patients’ plasma, as compared with the plasma of 40 healthy individuals. The proliferation ability of cells was monitored by the xCELLigence Real-Time Cell Analyzer (RTCA)-MP system. Transwell insert chambers with an 8 μm diameter porous membrane (Neuro Probe, MD, USA) were used for the migration/invasion assays. Also, the plasmid construction and luciferase reporter assay, western blotting analysis and immunofluorescence cell staining were performed. Data were analyzed with SPSS v.17.0 software. Results: We detected the expression level of miR-32 in two normal gastric tissue, the GES-1 cell line, and eight gastric carcinoma cell lines. The expression of miR-32 was significantly higher in tumor tissues as compared with normal tissues, p = 0.0016. The expression of miR-32 was significantly higher in 40 gastric carcinoma patients’ plasma, as compared with the plasma of 40 healthy individuals, p = 0.004.MiR-32 promotes the proliferation, migration and invasion of GC cells. The expression of KLF4 is negatively regulated by miR-32. Knockdown of KLF4 promotes cell proliferation, migration and invasion in GC cell-lines. Conclusions: In addition to identifying upregulated miR-32 as a diagnosis biomarker in clinical GC tissue and plasma, we have defined the biological functions of miR-32 as an oncogene in GC cells and explored the molecular mechanism of miR-32 in GC cells’ aggressive phenotype.