The Effect of Lentiviral Vector-Mediated RNA Interference Targeting Hypoxia-Inducible Factor 1α on the Uptake of Fluorodeoxyglucose ( 18 F) in the Human Pancreatic Cancer Cell Line,Patu8988

Abstract

Hypoxia can stimulate ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake in cultured tumor cells. This study has investigated the effect of lentiviral vector-mediated RNA interference (RNAi) targeting hypoxia-inducible factor 1α (HIF-1α) on the changes in HIF-1 and glucose transporter 1 (Glut-1) expression, the cell growth, and the uptake of ¹⁸F-FDG in the human pancreatic cancer cell line, Patu8988. Lentiviral RNAi vector targeting the HIF-1α gene (LV-HIF-1αRNAi) was constructed and used to treat cells at various concentrations (25–200 nM). The expression changes of HIF-1α and Glut-1 in hypoxic Patu8988 cells after RNAi treatment were determined using real time reverse transcription–polymerase chain reaction (real-time PCR). The inhibition rate of cell proliferation 48 hours after the addition of 10 μL of different concentrations of LV-HIF-1αRNAi (25–200 nM) was assayed using the MTT method. Meanwhile, the cell uptake of ¹⁸F-FDG was also assessed. After RNAi transfection, the relative expression levels of HIF-1α mRNA and Glut-1 under hypoxia were reduced and the relative expression levels of HIF-1α protein also decreased. Compared with the control group, the inhibition rates of cell proliferation under different viral dosages were 5.98%, 15.65%, 26.42%, and 40.81%, respectively, positively correlated with the viral doses (r=0.558, p<0.05). Under hypoxia, Glut-1 mRNA expression in Patu8988 cells treated with 200 nM of LV-HIF-1αRNAi for 24, 48, and 72 hours, respectively, was positively correlated with the inhibition rate of cell proliferation (r=0.618, p<0.05) as well as the inhibition rate of ¹⁸F-FDG uptake (r=0.664, p<0.05), while the latter two displayed a positive correlation with each other too (r=0.582, p<0.05). Under hypoxia, RNAi targeting HIF-1α significantly inhibited the expression of Glut-1 mRNA in Patu8988 pancreatic cancer cells and their uptake of ¹⁸F-FDG. These results suggest that LV-HIF-1αRNAi may form a new treatment for pancreatic cancer, and the effectiveness of the treatment can be readily assessed with ¹⁸F-FDG imaging.