Abstract
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Objectives MicroRNA (miRNA) has exhibited regulatory functions in numerous cellular processes including proliferation, differentiation and apoptosis, especially in carcinogenesis. In malignant tumors, the increased glucose metabolism is due to high expression of glucose transporters (GLUTs) and phosphorylation by hexokinase. The objective is to investigate the role of miRNA in the regulation of glucose transporter and further evaluate by FDG micro-PET in hepatocellular carcinoma (HCC) xenografts.
Methods The HepG2 cells stably overexpressing miRNA and empty vector were constructed by lentiviral vector transfection. The expression of insulin-like growth factor-1 receptor (IGF-1R), phosphatidyl- inositol-3-kinase (PI3K), AKT, and GLUT1 in HepG2 cells were evaluated by Western blotting assay. FDG cellular uptake and proliferated activity were evaluated. FDG micro-PET was performed to show the in-vivo ability of miRNA in HepG2 xenografts. Furthermore, the expression of glucose related proteins in tumor tissue were evaluated as well.
Results The hepG2 cells with stable expression of miRNA were constructed and identified by sequencing. The decreased proliferated ability was shown in miRNA over-expressed HCC cells in vitro, as well as FDG cellular uptake. Western blotting results showed the expression of IGF-1R, PI3K, AKT and GLUT1 protein were inhibited in miRNA over-expressed cells. For HepG2 tumor xenografts, small-animal PET clearly showed the significantly decreased FDG accumulation in miRNA tumors, which was verified by the suppressed FDG uptake and IGF-1R/PI3K/AKT pathway of ablated tumors.
Conclusions MiRNA exhibits a negative role in the regulation of glucose transporter via the inhibition of IGF-1R/PI3K/AKT pathway. FDG micro-PET is useful for evaluating the role of miRNA in vivo.
Research Support This study was supported by grants from the National Natural Science Foundation of China (NSFC 81101065, 31100604, 81071183), National Major Scientific Equipment Special Fund (2011YQ03011409) and the Higher Education Doctoral Program of China Research Fund for New Teacher (20110001120043)