MicroRNA-124 slows growth and spread of canine mammary cancer cells

Abstract

Canine mammary carcinoma (CMC) is the most common malignant tumor and the second leading cause of cancer-related mortality of dogs worldwide. MicroRNA-124 (miR-124) is an important tumor suppressor implicated in various aspects of carcinogenesis. However, the roles and mechanisms of miR-124 in CMC development remains to be determined. We used the quantitative real-time polymerase chain reaction (qRT-PCR) assay to evaluate the expression levels of miR-124 in CMC tissues obtained from 20 CMC cases and CHMm and CHMp cells. CMC cell lines were transfected with lipfactormine™2000, and the cell proliferation was measured by Cell Counting Kit-8 (CCK-8). Transwell assay were employed for evaluating the cell invasion and migration, while western blot assay was used to detect the protein changes in epithelial-mesenchymal transition (EMT) and CDH2 protein levels. The relationship between miR-124 and the 3'-untranslated region (3'-UTR) of CDH2 was predicted via bioinformatics analysis and verified by dual-luciferase reporter assay. The results revealed that miR-124 was reduced in CMC tissues and cell lines. Besides, observed high histological grade and tumor metastasis were associated with the down-regulation of miR-124 and up-regulation of CDH2. Functional analyses showed that in vitro transfection of CHMm and CHMp cells with miR-124 mimics inhibited their proliferation, migration, invasion, and EMT; however, transfection with miR-124 inhibitor resulted in the reversed effect. Besides, we showed that miR-124 directly suppressed the expression of CDH2, leading to the inhibition of CHMm cell proliferation and EMT. In conclusion, miR-124 regulates CMC tumor growth and EMT by targeting CDH2, maybe a potential therapeutic strategy against CMC.