ABSTRACT
Objective A variety of miRNAs have been found to be involved in the occurrence and development of colorectal cancer. This paper aim to investigate the clinical and biological relevance of miR-217 and the pathway by which miR-217 may be involved in progression in colorectal cancer. Methods According to the diameter of tumor, the tumor was divided into tumors>5 cm(n=22) and tumors≤5 cm(n=28); 18 cases of colorectal cancer I-II specimens and 32 of III-IV patients; according to median expression of miR-217, the specimens were divided into high expression group and low expression group. The expression of miR-217 in 50 colon cancer patients’ carcinoma and adjacent tissues was determined by qRT-PCR. Cells were grouped: overexpression control Group (transfected control mimic) and miR-217 overexpression group(transfected miR-217 mimic), low expression control group((transfected control inhibitor) and miR-217 low expression group(transfected miR-217 inhibitor), miR-217&ERK1/2 low expression group(transfected miR-217 inhibitor+U0126). MiR-217 and HCT116 cells were over expressed in SW480 cells,and miR-217 was knocked down. A series of biological function assays were performed to assess cell viability (cck-8 assay), clony formation ability (clony formation assay), proliferation (edu assay), Changes in ERK1/2 expression were measured at protein level, and the relationship between miR-217 and ERK1/2 in colorectal cancer cells was explored by relevant rescue experiments. Results Compared with colorectal adjacent noncancerous tissues, the expression of miR-217 was significantly decreased in carcinoma tissues(-1.360±0.645 vs 2.244±0.168, P<0.01); the expression of miR-217 in tumors with a diameter >5cm was significantly lower than that of tumors with a diameter ≤5cm(-1.718±0.272 vs -0.587±0.288, P<0.01); the expression of miR-217 in stage I-II colorectal cancer tissues was significantly higher than that stage III-IV(-0.413±0.330 vs -01.463±0.230, P<0.05); the expression of miR-217 in the miR-217 overexpression group was significantly higher than miR-217 overexpression control group(15.120±0.522 vs 1.004±0.003, P<0.01), and the number of clone formation was significantly less than that of the overexpression control group(199.30±15.62 vs 439.70±18.91, P<0.01) . In HCT116 cells, the expression of miR-217 in the miR-217low expression group was significantly lower than miR-217 low expression control group(0.2070±0.021 vs 1.006±0.003, P<0.01), and the number of clone formation was significantly higher than that control group(237.30±12.14 vs 117.00±7.00, P<0.01) . When miR-217 overexpressed in SW480, the protein expression of ERK1/2 decreased; when miR-217 was inhibited in HCT116, the protein expression of ERK1/2 increased. The number of colons in ERK1/2 low expression group was significantly lower than that miR-217&ERK1/2 low expression group(221.70±12.73 vs 108.00±5.51) , the difference was statistically significant(P<0.01). Conclusion Low expression of miR-217 is observed in both colorectal cancer tissues and cells, and miR-217 can affect tumor cell proliferation in the progression of colorectal cancer partly by inhibiting the expression of ERK1/2.