DTX3 inhibits cell migration, invasion, and epithelial-mesenchymal transition in colorectal cancer through the AKT signaling pathway.

Background: Colorectal cancer (CRC) is one of the most common malignant tumors of digestive system. As ubiquitin E3 ligases, Deltex (DTX) family proteins have been reported to be associated with multiple cancers. However, the role of Deltex-3 (DTX3) in CRC cells remains unclear. The study aimed to investigate the role of DTX3 in CRC. Methods: Gene Expression Profiling Interactive Analysis (GEPIA) and Human Protein Atlas (HPA) were used to analyze DTX3 messenger RNA (mRNA) and protein expression in CRC and para-cancerous normal (PN) tissues, HPA was used to analyze the DTX3 expression and the survival prognosis of CRC patients. Quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting (WB) and immunohistochemistry (IHC) were used to detect DTX3 mRNA and protein expression, in 80 CRC and PN tissues, and the relationships between DTX3 expression and clinicopathological characteristics of CRC patients were analyzed. DTX3 mRNA in CRC cells was knockdown or overexpressed using gene-editing tools and transfection efficiency was detected. Scratch and Transwell invasion assays were used to detect the effects of altered DTX3 mRNA expression on the migration and invasion ability of CRC cells, and the expression of epithelial-mesenchymal transition (EMT), AKT and p-AKT-related proteins were detected via WB. Results: GEPIA data analysis showed that the expression level of DTX3 mRNA in CRC tissues was significantly lower than PN tissues. HPA analysis showed positive DTX3 protein staining in PN tissues, and the greater overall survival in CRC patients with positive DTX3 staining (P=0.007). qRT-PCR and WB revealed the mRNA and protein expression levels of DTX3 in CRC tissues were significantly lower than PN tissues (t=0.851, P<0.001; t=0.914, P<0.001), and IHC revealed the DTX3 positive staining in CRC tissues was lower than PN tissues (P<0.001). In addition, the expression of DTX3 was correlated to the depth of tumor invasion, degree of lymph node metastasis and tumor-node-metastasis (TNM) stage of CRC patients. DTX3 mRNA and protein expression in the short hairpin RNA (DTX3-shRNA) group was significantly decreased; in contrast the pcDNA3.1-DTX3 group. Scratch and Transwell experiments revealed the migration and invasion ability of CRC cells was significantly greater in the DTX3-shRNA group than the control and knockdown empty group (neg-shRNA) group, whereas the pcDNA3.1-DTX3 group was significantly lower than the control and pcDNA3.1 group. Compared with the control and pcDNA3.1 group, the average expression levels of Vimentin and p-AKT proteins in the pcDNA3.1-DTX3 group were significantly lower, whereas the E-cadherin protein level was significantly greater. In contrast, this trend was reversed when DTX3 mRNA was knockdown in CRC cells, and there was no significant difference in the expression levels of these proteins between the control and neg-shRNA or pcDNA3.1 group. Conclusions: DTX3 inhibits CRC migration, invasion and EMT through the AKT signaling pathway, and DTX3 could be used to a novel biomarker inhibit CRC progression.