MicroRNA‑329 serves a tumor suppressive role in colorectal cancer by directly targeting transforming growth factor beta‑1.

Colorectal cancer (CRC) is the third most common type of diagnosed cancer and the fourth leading cause of cancer‑associated mortalities worldwide. Increasing studies have demonstrated that the deregulation of microRNAs (miRNAs or miRs) is associated with the occurrence and development of multiple types of human cancer, including CRC. miR‑329 has been identified to be downregulated in various types of cancer; however, its expression pattern, functions and mechanisms in CRC remain unclear. The present study demonstrated that miR‑329 was lowly expressed in CRC tissue samples and cell lines. Low expression of miR‑329 was correlated with tumor‑node‑metastasis stage and lymph node metastasis in patients with CRC. In vitro experiments revealed that resumption expression of miR‑329 suppressed cell proliferation and invasion in CRC. Furthermore, the results of the present study indicated that miR‑329 targets transforming growth factor‑β1 (TGF‑β1) directly in vitro. TGF‑β1 was demonstrated to be upregulated in CRC tissue samples and inversely correlated with miR‑329 expression. Upregulation of TGF‑β1 was able to partially counteract the antitumor roles of miR‑329 on CRC cell proliferation and invasion. The results of the current study revealed that miR‑329 suppresses CRC cell proliferation and invasion through targeting TGF‑β1, thus suggesting that targeting miR‑329/TGF‑β1 may provide a novel effective therapeutic approach for the treatment of patients with CRC.