SNAI2/FTH1P3/miR-218-5p Positive Feedback Loop Promotes Colorectal Cancer Metastasis

Colorectal cancer (CRC) is a type of intestinal cancer that causes more than 600,000 deaths every year. Overcoming the problems of metastasis requires detailed studies to reveal the potential molecular mechanisms. This study aims to reveal the molecular mechanism of CRC metastasis involving non-coding RNA regulation. The expression profile of FTH1P3 was analyzed based on the data of TCGA-COAD patient cohorts. Q-PCR analysis was performed to validate the expression of FTH1P3 in colorectal cancer cells. JASPR was used to screen transcription factors of FTH1P3. q-ChIP analysis was used to validate the target between FTH1P3 and transcription factor. Scratch assay and transwell assay were used to evaluate the migration and invasion ability of colorectal cancer cells. FTH1P3 is highly expressed in CRC patient cohort. FTH1P3 induced migration and invasion of SW480 cell through regulating epithelial-mesenchymal transition (EMT). In addition, FTH1P3 is a direct target of SNAI2. SNAI2 promotes the expression of FTH1P3. Both FTH1P3 and SNAI2 were directly targeted and repressed by miR-218-5p. Interestingly, ectopic FTH1P3 caused a decreased miR-218-5p level and an elevated nucleic SNAI2 protein expression level. Of note, only ectopic SNAI2 protein resulted in a repressed miR-218-5p and an increased FTH1P3, whereas SNAI2 3'UTR failed to affect the expression of miR-218-5p and FTH1P3. SNAI2 transcriptionally activates FTH1P3 expression. Both SNAI2 and FTH1P3 are targets of miR-218-5p. SNAI2/FTH1P3/miR-218-5p form a positive feedback loop in the regulation of CRC metastasis.