Modulation of Rab5A expression regulated the migration and invasion ability of human hepatoma cells Free

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Hepatoma is the leading cause of malignant tumors in Taiwan. Our previous microarray analysis found that Rab5A was among several genes with increased expression in hepatoma as compared to non-tumorous liver tissue. Small GTPases of the Rab family are important modulators of vesicle formation. Rab5A is an early rate limiting control factor of receptor internalization and related with actin remodeling. In this study, we have examined and compared the expression of Rab5A in 16 paired hepatoma and adjacent liver tissue samples from patients with or without recurrence. Quantitative PCR results found that the Rab5A mRNA level was higher in tumors from patients with recurrence. Immunostaining and RT-PCR analyses confirmed the expression of Rab5A in human hepatoma cell lines. In addition, Western blot analyses showed that Rab5A was differentially expressed in three human hepatoma cell lines. In order to understand the relationship between Rab5A expression and cell migration, we found that transiently transfected Rab5A siRNA into HA22T/VGH cells or stably knockdown Rab5A in HA22T/VGH cells significantly decreased the expression of Rab5A at 48 hours. Trypan blue exclusion, MTT assay and flowcytometry analyses revealed that reduced expression of Rab5A decreased the cell proliferation but had no effect on cell cycle progression of Rab5A knockdown HA22T/VGH cells. HA22T/VGH cells with transient or stable knock down Rab5A showed reduced invasion and migration ability using invasion and motility assays. In addition, the MMP-9 production was decreased in Rab5A knockdown clones. These results together suggest that Rab5A may play an important role in metastasis of human hepatoma cells.