The inhibitory effect of miR-375 targeting sp1 in colorectal cancer cell proliferation.

OBJECTIVE: Sp1 is a member of super zinc finger structure family that participates in cancer cells' apoptosis, proliferation, survival, and differentiation. This study detected the expressions of miR-375 and sp1 in colorectal cancer tissue and cells to analyze their impact on cell proliferation.

PATIENTS AND METHODS: Colorectal cancer patients in our hospital were enrolled. HCT-116 cell was transfected with miR-375 mimics, mimics control, and miR-375 + sp1, respectively. RT-PCR and Western blot were applied to detect expressions of miR-375 and sp1 at mRNA and protein level in colorectal cancer tissue, para-carcinoma tissue, and normal colorectal tissue. RT-PCR and Western blot were used to test levels of miR-375 and sp1 in HCT-116 cells after transfection. MTT assay was performed to determine HCT-116 cell proliferation.

RESULTS: Our data showed that miR-375 was downregulated, while sp1 was overexpressed in colorectal cancer tissue compared with that in para-carcinoma tissue and normal control (p < 0.05). MiR-375 level was elevated, while sp1 mRNA was declined after miR-375 mimic transfection (p < 0.05). Compared with miR-375 mimic group, the levels of miR-375 and sp1 showed no difference in miR-375 + sp1 group (p > 0.05). Of note, the increase of MiR-375 and reduction of sp1 were in a time-dependent manner (p < 0.05). The cell proliferation rate in miR-375 mimic group was significantly decreased compared with that in mimic control and blank group (p < 0.05). The cell proliferation rate in miR-375 + sp1 group was significantly higher than that miR-375 group, but still lower than the control (p < 0.05). The proliferation rate gradually declined in a time-dependent manner (p < 0.05).

CONCLUSIONS: MiR-375 was decreased and sp1 level was enhanced in colorectal cancer. MiR-375 suppresses the proliferation of colorectal cancer cells via the inhibition of sp1 expression at posttranscriptional level.