MiR-144 inhibits growth and metastasis in colon cancer by down-regulating SMAD4

Purpose: MicroRNAs (MiRs) are thought to display regulator action in tumor suppression and oncogenesis. MiR-144 plays an important role in the development of various cancers, such as colorectal cancer, breast cancer and lung cancer, by targeting different molecules potentially involved in many signalling pathways. SMAD4 is a common signaling during tumor progression, and it can inhibit cell proliferation and promote cell motility in most epithelial cells. This study focused on the effect of miR-144 and SMAD4 on colon cancer in order to find the novel gene therapy target for the treatment of colon cancer. Patients and methods: Quantitative real-time polymerase chain reaction (qRT-PCR) was used to assess the expression level of miR-144 in colon cancer tissues and SW620 cells. MTT assay, scratch test, and transwell assay were used to evaluate cell proliferation, migration and invasion, respectively. Moreover, luciferase assays were utilized to identify the predictive effect of miR-144 on SMAD4. Western blot was performed to determine the relative expression of protein related to SMAD4. Results: We found miR-144 level was significantly lower in colon cancer tissues and SW620 cells. Moreover, SMAD4 level, both in mRNA and protein, was obviously elevated in colon cancer tissues. Further, miR-144 mimics treatment inhibited cells proliferation, invasion and migration. Fluorescence intensity of miR-144 mimics group in wild type cells was decreased. MiR-144 mimics repressed the SMAD4 expression both in mRNA and protein. Conclusion: These findings about miR-144/SMAD4 pair provide a novel therapeutic method for colon cancer patients.