MicroRNA-128 targeting RPN2 inhibits cell proliferation and migration through the Akt-p53-cyclin pathway in colorectal cancer cells.

Colorectal cancer (CRC) is a malignancy with high metastatic rates. The mechanism of miR-128 on the regulation of Ribophorin-II (RPN2) in CRC cells was explored in the present study. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) or western blot analyses were conducted to detect miR-128 and RPN2 levels in tissues and cell lines. AmiR-128 overexpression model was constructed using miR-128 mimic transfection in HT29 CRC cells. Then, cell proliferation was detected using a Cell Counting Kit-8 assay, and the migratory and invasive abilities were measured by Transwell assay. RT-qPCR and western blot analysis were used to detect expression levels of protein kinase-B (Akt)-tumor protein 53 (p53)-cyclin pathway and metastasis-associated factors. In the present study, it was identified that aberrant decreased miR-128 was negatively correlated with RPN2 in CRC tissues. The increased RPN2 levels were significantly associated with poorly-differentiated histology, advanced stages and lymph nodes metastasis in patients with CRC. The survival rate of patients with CRC was also closely associated with RPN2 levels. In HT29 cells, miR-128 upregulation downregulated mRNA and protein levels of RPN2, and significantly inhibited cell proliferative, migratory and invasive abilities. Markedly decreased Akt phosphorylation and cyclin D1 levels and increased p53 levels were detected when cells were transfected with miR-128 mimics. Concurrently, decreased levels of matrix metalloproteinase (MMP)-2, MMP-9 and metastasis-associated protein 1, and increased levels of epithelial-cadherin and tissue inhibitor of metalloproteinases 2, were revealed in miR-128 mimic-transfected cells. Subsequent to screening with miRNA target prediction databases, the specificity of miR-128-targeted RPN2 was validated by a luciferase reporter assay. In conclusion, the results suggested that miR-128 was a specific negative regulator of RPN2, which regulated colorectal cancer cell proliferation and migration by affecting the Akt-p53-cyclin pathway. These data may provide novel evidence for the therapeutic potential of miR-128-based treatments for colorectal cancer.