Circular RNA circ-SMAD7 is downregulated in colorectal cancer and suppresses tumor metastasis by regulating epithelial mesenchymal transition.

OBJECTIVE

Recently, circular RNAs play a vital role in many diseases including tumor progression. Colorectal cancer (CRC) is one of the most ordinary malignant tumors. The purpose of our study is to detect the potential function of circ-SMAD7 in CRC.

PATIENTS AND METHODS

The level of circ-SMAD7 was detected by Real Time-quantitative Polymerase Chain Reaction (RT-qPCR) in CRC tissue samples. The circ-SMAD7 expression level and the patients' overall survival time were analyzed. Functional experiments were conducted to identify the changes of the biological behaviors in CRC cells after the overexpression of circ-SMAD7. The transwell assay, the Matrigel assay, and the Wound healing assay were conducted. The Western blot assay was performed to analyze the effect of circ-SMAD7 on the epithelial-to-mesenchymal transition (EMT) process.

RESULTS

In the research, the expression level of circ-SMAD7 was significantly decreased in CRC tissues compared with that in the adjacent samples. Circ-SMAD7 expression was positively associated to patients' overall survival time. The expression of circ-SMAD7 was also decreased in CRC cell lines. The upregulation of circ-SMAD7 led to the inhibition of cell migration and invasion in CRC. In addition, the results of further experiments revealed that the EMT-related proteins were regulated via overexpression of circ-SMAD7 in CRC.

CONCLUSIONS

These results suggest that circ-SMAD7 could inhibit cell migration and invasion of CRC by suppressing the EMT process, which might offer a potential therapeutic target for CRC.