Promoting invasive ability of hepatocellular carcinoma by co-culture of exosomes from tumor cells with high metastatic potential

Objective To observe the effect of co-culture of exosomes from tumor cells with high metastatic potential on hepatocellular carcinoma (HCC) cells with low invasive ability and explore the possible molecular mechanism. Methods The supernatant of 4 HCC cell lines of MHCC97H, MHCC97L, SMMC7721 and Hep3B, and plasma of 46 HCC patients were collected to extract, purify and identify exosomes. Hep3B cells with low invasive potential were co-cultured with exosomes. The invasive ability of Hep3B cells was detected by invasive assay, polymerase chain reaction (PCR) was used to test the circular RNA (circRNA) level, and the gelatinase spectrum assay was applied to examine the activity of matrix metalloproteinase (MMP). Results Exosomes were extracted, purified and identified successfully. The circRNA_100338 level in the HCC exosome of patients with lung metastasis (0.064±0.006) was higher than that of HCC exosome of patients without lung metastasis (0.039±0.005); The circRNA_100338 level in the exosome of MHCC97H cells with high metastatic potential (0.083±0.005) was higher than that of the exosome of Hep3B cells with low metastatic potential (0.021±0.003); The invasive ability of Hep3B cells was elevated significantly after co-culturue with exosomes from MHCC97H cells, and the number of cells penetrating membranes was increased (15.3±2.5 vs. 8.7±2.1). The circRNA_100338 level was increased in co-culture group (0.019±0.002 vs. 0.007±0.001). The MMP-9 activity was gradually increased (0.062±0.001, 0.147±0.002, 0.315±0.003). All differences were statistically significant (P<0.05). Conclusion Exosomes from cells with high metastatic potential promote HCC invasion, which is related to the activated MMP-9 and elevated circRNA_100338 level in exosomes. Key words: Carcinoma, hepatocellular; Exosome; Circular RNA; Invasion