To investigate the effect of tumor protein P53 inducible nuclear protein 2 (TP53INP2) on invasion and metastasis of breast cancer cells.

The invasive (MDA-MB-231-M) and non-invasive (MDA-MB-231-NM) breast cancer cells were screened by Transwell cell method. Then pCMV6-TP53INP2 overexpression recombinant vector plasmid was transfected into MDA-MB-231-NM cells as OE-TP53INP2 group, while pRS-sh-TP53INP2 interference vector plasmid was transfected into MDA-MB-231-M cells as sh-TP53INP2 group. Cells of OE- TP53INP2 group were transfected with β-catenin interference plasmid or Wnt/ β-catenin signaling pathway inhibitor (XAV-939) , which were divided into OE-TP53INP2+si-β-catenin group and OE-TP53INP2 + XAV-939 group respectively. Quantitative real-time PCR (RT-qPCR) was used to detect the expression of TP53INP2 in MDA-MB-231-NM and MDA-MB-231-M cells, and Transwell assay was used to detect the migration and invasion ability of MDA-MB-231-NM and MDA-MB-231-M cells, TOPflash/FOPflash experiment was used to detect the activity of Wnt/ β-catenin signaling pathway, and Western blot was used to detect the protein expression levels of TP53INP2, β-catenin, epithelial marker epithelial cadherin (E-cadherin) , mesenchyme markers N-cadherin and vimentin. The quantitative data of the two groups were compared through t-test. One-way analysis of variance was used to compare the difference among multiple groups, and SNK-q test was used to compare the difference between groups.

Compared with non-invasive MDA-MB-231- NM cells, the protein expression levels of N-cadherin, vimentin and TP53INP2 in invasive MDA-MB-231-M cells were increased (1.00±0.10 vs 3.15±0.07, 1.00±0.07 vs 2.35 ± 0.06, 1.00±0.04 vs 2.13±0.07) , but the protein expression level of E-cadherin was decreased (1.00±0.06 vs 0.37±0.05) , and the difference was statistically significant (P < 0.001) ; at the same time, the number of migration and invasion of cells (43.67±13.25 vs 154.33±15.05, 46.67±12.70 vs 162.33±16.50) was significantly increased (P < 0.001) . Compared with the control group, the protein expression levels of N-cadherin, vimentin and β-catenin were increased in TP53INP2-overexpressed MDA-MB-231-NM cells (1.00±0.06 vs 1.85±0.07, 1.00±0.07 vs 2.14±0.04, 1.00±0.11 vs 3.63±0.05) , whereas the protein expression level of E-cadherin was decreased (0.43±0.05 vs 1.00±0.05) , and the difference was statistically significant (P < 0.001) ; And the number of migration and invasion of cells (118.00±12.45 vs 318.67±12.50, 81.67±12.87 vs 287.33±11.70) was significantly increased (P < 0.001) . But all the results were opposite after interference with the TP53INP2 gene. Meanwhile, compared with the TP53INP2 overexpression group, when TP53INP2 overexpression simultaneously interfered with β-catenin, the protein expression levels of N-cadherin and vimentin in cells were decreased (2.65±0.07 vs 0.46±0.05, 4.23±0.08 vs 2.34±0.04) , the protein expression level of E-cadherin was increased (0.24±0.04 vs 1.12±0.08), and the difference was statistically significant (P <0.001) ; and the number of migration and invasion of cells (62.00±8.82 vs 170.67±12.05, 76.00±12.82 vs 122.67±13.70) were significantly decreased (P < 0.001) . Interestingly, similar results were obtained after overexpression of TP53INP2 combined with Wnt/β-catenin signaling pathway inhibitor (XAV-939) .

TP53INP2 can regulate E-cadherin, N-cadherin, and vimentin proteins by activating the Wnt/β-catenin signaling pathway, thus promoting the invasion and metastasis of breast cancer cells.