MicroRNA-320 family is downregulated in colorectal adenoma and affects tumor proliferation by targeting CDK6

Figure 1 MiRNA expression profiles of matched samples. A: Regions of colorectal carcinoma, pre-existing adenoma, and adjacent non-neoplastic mucosa in a resection specimen were microdissected using laser microdissection (LMD); B and C: The miRNA expression profiles were compared with three matched regions from LSTs (n = 3) and protruded tumors (n = 3). For each miRNA, red represents higher expression and green represents lower expression than the average expression. LST: Laterally spreading type; C: Carcinoma; A: Adenoma; N: Adjacent non-neoplastic mucosa.

Figure 2 The relative expression levels of the miR-320 family in formalin-fixed, paraffin-embedded samples and cell lines. A: The expression of the miR-320 family in 18 samples (15 colorectal carcinoma with adenoma and 3 colorectal carcinoma without adenoma); B: The expression of the miR-320 family in human colon cancers cell lines (HT29 and SW480) compared with that in human intestinal epithelial cells (InEpC). (^aP < 0.05, ^bP < 0.01). C: Carcinoma, A: Adenoma, N: Adjacent non-neoplastic mucosa.

Figure 3 The miR-320 family inhibits colon cancer cell proliferation. Cell proliferation in SW480 transfected with the miR-320 family was assessed by the MTS assay, each day, for up to 5 d (^aP < 0.05).

Figure 4 The miR-320 family targets CDK6. A: Seven candidate target genes of miR-320a were identified as being common from the results of expression profiling and two bioinfomatics algorithms. The decreased expression of 497 pieces was observed in gene expression profiling of SW480 transfected with an miR-320a mimic and a mimic control (fold-change: < 0.67), and target genes of miR-320a were predicted by TargetScan and Pic tar; B: CDK6 has a putative miR-320 family-binding site mapped to the 3′ UTR; C and D: mRNA and protein levels of CDK6 in colon cancer cell lines (HT29 and SW480) transfected with miR-320 family mimics and a mimic control; E: The relative CDK6 expression level compared with that in non-neoplastic mucosa in 16 matched samples; F-J: Pearson’s correlation analysis between the expression levels of the miR-320 family and CDK6 in 16 matched samples (^aP < 0.05). UTR: Untranslated regions; 320am: miR-320a mimics; 320bm: miR-320b mimics; 320cm: miR-320c mimics; 320dm: miR-320d mimics; 320em: miR-320e mimics; mc: Mimic control; C: Carcinoma; A: Adenoma; N: Adjacent non-neoplastic mucosa.