CDX2/mir-145-5p/SENP1 Pathways Affect LNCaP Cells Invasion and Migration

Background/Aims: Recently, rapidly accumulating evidence has shown that microRNAs (miRNAs) are involved in human tumorigenesis, and the dysregulation of miRNAs has been observed in many cancers, including prostate cancer. miR-145-5p, an miRNA with reduced expression in prostate cancer cells, has been shown to have a tumor suppressive role in a variety of tumors. However, its underlying mechanism requires further elucidation. Methods: A lentiviral expression vector for miR-145-5p was constructed and used to establish a stable cell line (LNCaP) expressing miR-145-5p. The cells were cultured normally and divided into the control group (control), negative control group (negative control), and test group (miR-145-5p). Inhibition of proliferation was measured by a WST-8 assay. The early apoptosis rate of cells was detected by flow cytometry. Clone formation ability was detected by a clone formation inhibition test. Cell invasion and migration capacity was detected by a Transwell assay. The relative expression levels of proteins were detected by western blotting. We constructed a nude mouse model of prostate cancer to observe the effect of miR-145-5p on the growth of transplanted tumors. TargetScan bioinformatics software was used to predict target genes regulated by miR-14-5p. ChIPBase was used to predict transcription factors with binding sites in the upstream promoter region of miR-145-5p. Quantitative reverse transcription PCR was used to detect the relative expression level of genes. A bifluorescence-reporter gene vector was constructed to confirm the regulation of target genes by miR-145-5p. We used 5' rapid amplification of cDNA ends to confirm the transcription start site of miR-145-5p.Chromatin immunoprecipitation technology was used to detect the effect of transcription factors binding to miR-145-5p. Results: The overexpression of miR-145-5p not only inhibited the proliferation, invasion, and migration of LNCaP cells but also promoted their early apoptosis. After overexpressing miR-145-5p, the expression of small ubiquitin-like modifier protein-specific protease 1 (SENP1), and caudal-related homeobox 2 (CDX2) protein was decreased in LNCaP cells. The transcription factor CDX2 bound to the miR-145-5p promoter region and inhibited its transcription. The transcription start site of miR-145-5p was located at a guanine residue 1,408 bp upstream of the stem-loop sequence. Upon overexpression, miR-145-5p could bind to the 3'-untranslated region of SENP1 to inhibit its translation. Conclusion: These results suggested that CDX2 inhibits the expression of miR-145-5p, thereby relieving the inhibitory effect of miR-145-5p on the translation of SENP1 and affecting the invasion and migration of prostate cancer cells.