Inhibition And Regulation Mechanism Of Mir-22 Ovarian Cancer Invasion And Metastasis

Objectives. This work is aimed to identify the regulatory effect of miR-22 on cell migration, invasion, growth and apoptosis in ovarian cancer, and to make a general analysis of miR-22's downstream functional targets with an attempt to gain a better understanding of miR-22's role in ovarian cancer.Methods. (1)We examined the distinct miRNA expression profiles between paired low-metastatic human serous ovarian cancer cell SKOV-3 and high-metastatic human serous ovarian cell SKOV-3ip using miRNA microarray. Particularly, Real-time RT-PCR was performed to validate miR-22 expression level in paired SKOV-3/SKOV-3ip cells and HO-8910/HO-8910PM cells respectively. (2) Gain-of-function study and loss-of-function study was respectively performed in SKOV-3ip cells, with a relatively higher expression level of miR-22, and SKOV-3 cells, with a relatively lower expression level of miR-22, to monitor the changes in cell invasion and migration, cell growth, and cell apoptosis. (3) Three bioinformatics databases(TARGETSCAN, http://www.targetscan.org, MIRANDA, http://www.microrna.org and PICTAR, http://www.pictar.mdc-berlin.de) was employed to screen the potential targeting genes of miR-22. In particular, we validate the regulatory effect of miR-22 on Tiaml expression by dual-luciferase reporter assay, Western Blot and Real-time RT-PCR.Results. (1) Validation by Real-time RT-PCR revealed that miR-22 was decrease in SKOV-3ip cells and HO-8910PM cells, compared with their counterparts, SKOV-3 cells and HO-8910 cells, respectively. (2) Both gain-of-function and loss-of-function study displayed an negative effect of miR-22 on cell invasion and migration in vitro without significantly affecting cell viability and apoptosis. (3) Subsequent bioinformatics analysis revealed that miR-22 might regulate multiple pro-metastatic genes. Particularly, regulatory study of miR-22 in Tiam1 expression was performed. Our results showed that Tiam1 was a direct target of miR-22, revealed by dual-luciferase reporter assay, and alteration of miR-22 expression had a negative regulatory effect on Tiam1 protein level and mRNA level, demonstrated respectively by Western Blot and Real-time RT-PCR.Conclusions. Taken together, our findings suggested that miR-22 might be involved in inhibiting ovarian cancer metastasis, probably by targeting Tiam1.