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.