Figure 4

Stable ectopic miR-31 expression suppresses the anchorage-independent growth and in vivo tumorigenicity of NPC cells. (a) Expression of miR-31 was demonstrated in the stably miR-31-transfected C666-1 cell clones (miR31#1 and miR31#2) by quantitative RT-PCR. The immortalized normal nasopharyngeal epithelial cells NP69 was included as control. (b) In the two stably miR-31-transfected NPC cell clones (miR31#1 and miR31#2), obvious growth inhibition was demonstrated by WST-1 assay. (c) Stable expression of miR-31 inhibits the anchorage-independent growth of C666-1 cells. Obviously reduction in number and size of colonies in the stable miR-31-expressing cells were demonstrated by soft agar assay. (d) In vivo tumorgenic assay in nude mice showed that tumors formed in the sites implanted with C666-1 cells expressing miR-31 (miR-31#1 and miR-31#2) were consistently smaller than those implanted with vector controls. Photographs showing the nude mice (upper row) inoculated with stable clones (vector, miR-31 #1, #2) and tumors extracted (bottom row) on day 38 after inoculation were also shown. Four nude mice were used in the experiment and data was shown with mean ± SEM. Student-t test was used for statistical significance, with a p-value of less than 0.05 was considered significant (*p < 0.05, **p < 0.01, ***p < 0.001).