MicroRNA-203a-3p is a candidate tumor suppressor that targets thrombospondin 2 in colorectal carcinoma

The aim of the present study was to investigate the role of miR-203a-3p in colorectal cancer (CRC) and identify the target gene of microRNA (miR)-203a-3p. A total of 59 sets of cancer tissues and corresponding adjacent non-tumor tissues were collected from CRC patients (aged 31–78 years) between October 2016 and May 2017. Total RNA extraction and reverse transcription-quantitative polymerase chain reaction analysis, transfection assay, and Transwell and apoptosis assays, western blot analysis, a luciferase reporter assay and immunohistochemistry were performed. miR-203a-3p was found to be significantly downregulated in CRC tissues compared with adjacent normal tissues. The overexpression of miR-203a-3p was shown to inhibit the invasion and migration of human CRC SW480 and HT29 cells, and increase their apoptosis rates. Furthermore, miR-203a-3p downregulated the expression of thrombospondin 2 (THBS2) in SW480 and HT29 cells. It was also experimentally demonstrated that miR-203a-3p binds to the 3′-untranslated region of THBS2, downregulating THBS2 expression and thereby inhibiting CRC progression and metastasis. The expression of miR-203a-3p, which serves a tumor-suppressive role, in CRC tissues was significantly downregulated. As miR-203a-3p was determined to target THBS2 to inhibit CRC progression and metastasis; thus, miR-203a-3p may be considered as a potential novel approach to treating CRC.