MicroRNA-133b inhibits connective tissue growth factor in colorectal cancer and correlates with the clinical stage of the disease

Accumulating evidence indicates that dysregulation of microRNA-133b (miR-133b) is an important step in the development of certain types of human cancer and contributes to tumorigenesis. Altered expression of miR-133b has been reported in colon carcinoma, but its association with clinical stage in colorectal cancer (CRC) has remained elusive. Connective tissue growth factor (CTGF), a potentially promising candidate gene for interaction with miR-133b, was screened using micro- array analysis. The expression of miR-133b and CTGF was evaluated using reverse transcription-quantitative polymerase chain reaction and western blot analysis. The regulatory effects of miR-133b on CTGF were evaluated using a dual-luciferase reporter assay. CTGF was identified as a functional target of miR-133b. The results demonstrated low expression of miR-133b in CRC specimens with poor cell differentiation (P=0.011), lymph node metastasis (P=0.037) and advanced clinical stages (stage III or IV vs. I or II; P=0.036). Furthermore, there was a significant association between a high level of expression of CTGF mRNA and an advanced clinical stage (stage III or IV vs. I or II; P=0.015) and lymph node metastasis (P=0.034). CTGF expression was negatively regulated by miR-133b in the human colorectum, suggesting that miR-133b and CTGF may be candi- date therapeutic targets in colorectal cancer.