Objective      To determine the effect of silencing monoacylglycerol lipase by short hairpin RNA (shRNA) on the metastasis of hepatocellular carcinoma in rats by using ultrasound-targeted microbubble destruction.

       Methods      Liver tumor models of rats were established by intragastrically injection of 0.2% DEN in 5 times per week for 14 weeks. The successful establishment of tumor model was testified by pathologic biopsy and two-dimensional ultrasongraphy. Totally 40 rats with liver tumor were randomly divided into 4 groups

phosphate-buffered solution (PBS) group

lipid microbubbles loaded MAGL-shRNA (MAGL-shRNA+microbubble group)

pure lipid microbubbles+ultrasound (MB+US group)

and lipid microbubbles loaded MAGL-shRNA+ultrasound (MAGL-shRNA+MB+US group). The microbubbles of 1 mL containing MAGL-shRNA plasmid or not were injected through tail vein. Ultrasound radiation was applied on the rats of MB+US and MAGL-shRNA+MB+US groups after the injection of target gene

with the radiation frequency of 1 kHz

sound intensity of 2 W/cm

2

with the pulse irradiation of 10 s and interval time of 10 s for totally 20 min. The expression of MAGL protein was detected in the tumor mass by Western blotting. Protein expression of MAGL and matrix metalloproteinase-2 (MMP-2) was detected by immunohistochemistry (IHC). Tumor metastasis were observed and compared among different groups.       Results      The protein expression of MAGL was significantly higher in HCC tissue than in normal tissue (

P

0.05). Microbubbles containing MAGL-shRNA were injected precisely into the tumor tissue and then released to the target

and the expression of MAGL protein was found in all HCC tissue. Its expression in MAGL-shRNA+MB+US group was significantly lower than the other groups (

P

0.01). The MMP-2 expression detected by IHC in MAGL-shRNA+MB+US group was significantly lower than others (

P

0.01). Tumor metastasis was found in all groups

but the metastasis rate in MAGL-shRNA+MB+US group was the lowest (

P

0.05).       Conclusion      Ultrasound targeted microbubble destruction can effectively transfect MAGL-shRNA into the target tissues

and play a inhibitory effect on the metastasis in liver cancer through MAGL-MM

P-2 signal pathway.