ABSTRACT
Vascular endothelial growth factor 165 (VEGF(165))-mediated autocrine stimulation of tumor cells enhances the progression to a malignant phenotype. VEGF(165)b competes with VEGF(165) and binds to vascular endothelial growth factor receptor (VEGFR), resulting in inhibition of downstream signal transduction pathways. This study was designed to investigate the role of VEGF(165)b in the migration and invasion of human lung adenocarcinoma A549 cells. The full-length of VEGF(165)b was constructed and cloned into an expression plasmid (pVEGF(165)b), and then transfected into A549 cells. Dimethylthiazolyl- 1 -2, 5-diphenyltetrazolium bromide (MTT) assay was used to detect the effect of VEGF(165)b on proliferation of transfected cells. Reverse transcription polymerase chain reaction (RT-PCR) was employed to examine the effect of VEGF(165)b on the expression of VEGF(165) in transfected cells. Wound-healing assays were used to investigate the effect of VEGF(165)b on migration of transfected cells. Matrix metalloproteinase (MMPs) activity assay and in vitro invasion assay were used to determine the role of VEGF(165)b in invasion of transfected cells. There was no significant change in proliferation of A549 cells after transfection of pVEGF(165)b, but the expression of VEGF(165), migration and invasion in A549 cells were inhibited. Furthermore, exogenous VEGF(165)b inhibited the activity of MMP9 in the supernatant of A549 cells and the subsequent invasion capacity of those cells. We therefore conclude that exogenous VEGF(165)b can inhibit the expression of VEGF(165), as well as the migration and invasion of A549 cells, but has no effect on the proliferation of A549 cells.
ABSTRACT
The present study investigated the enhanced radiosensitivity of U-251 cells induced by sodium butyrate (NaB) and its possible mechanisms. Increased radiosensitivity of U251 cells was examined by clonogenic cell survival assays. The expression of Ku70 mRNA and protein was detected by using RT-PCR and Western blotting respectively. γ-H2AX foci were measured at different time points after ionizing irradiation alone or combined with NaB treatment. The results showed that cell survival rate was significantly reduced, both D0 and Dq values were decreased (D0: 1.43 Gy vs. 1.76 Gy; Dq: 1.22 Gy vs. 2.05 Gy) after the combined treatment as compared with irradiation alone, and sensitivity enhancing ratio (SER) reached 1.23. The average number of γ-H2AX foci per cell receiving the combined treatment was significantly increased at different time points, and the expression levels of Ku70 mRNA and protein were suppressed by NaB in a dose-dependent manner. It was concluded that enhanced radiosensitivity induced by NaB involves an inhibited expression of Ku70 and an increase in γ-H2AX foci, which suggests decreased ability in DSB repair.