Supplementary Material for: Significance of miR-148a in Colorectal Neoplasia: Downregulation of miR-148a Contributes to the Carcinogenesis and Cell Invasion of Colorectal Cancer

Objective: Colorectal cancer (CRC) develops through the deregulation of gene expression and the accumulation of epigenetic abnormalities, leading to tumor cell acquisition of malignant features. MicroRNAs (miRNAs) play a critical role in cancer development, where they can act as oncogenes or oncosuppressors. Methods: miR-148a expression was measured by qRT-PCR in patients with colorectal adenoma (n = 21) and CRC (stage I-IV, n = 159) using formalin-fixed paraffin-embedded tissue samples. In situ hybridization (ISH) using an miR-148a-specific probe was also performed. To further confirm the direct effect of miR-148a on matrix metalloproteinase (MMP)7 expression in CRC, MTT and cell invasion assays using HT29 and WiDr cells were performed. Results: miR-148a expression was found to be clearly downregulated in high-grade adenoma compared to low-grade adenoma on both qRT-PCR and ISH analysis. Downregulation of miR-148a expression was significantly correlated with advanced clinicopathological features and was an independent prognostic classifier in patients with stage III CRC. In CRC cells and tissues, miR-148a expression was inversely correlated with the expression of MMP7. Conclusion: We showed the collaborative participation of miR-148a and MMP7 in CRC cell invasion. These results also demonstrate that the downregulation of miR-148a expression promotes CRC progression, especially carcinogenesis and cancer cell invasion.