The Mechanism In DACH1 Inhibiting Invasion And Metastasis Of Breast Cancer Cells

Among females,breast cancer is the most common type of carcinoma and it ranks first in terms of incidence and mortality.Currently,no effective therapies can cure metastatic breast cancer;therefore,tumor metastasis leads to high mortality in breast cancer patients.Matrix metalloproteinases(MMPs)are the main enzymes that degrade the extracellular matrix.Among them,MMP9 can degrade the main components of the extracellular matrix and play an important role in tumor cell invasion and metastasis.The expression of DACH1 is deficient or down-regulated in multiple carcinomas,suggesting that DACH1 might be a new tumor suppressor gene.Studies show that DACH1 can inhibit the invasion and metastasis of breast cancer cells,but its mechanism is still not comprehensive.This study explores the molecular mechanism of DACH1 inhibiting invasion and metastasis of breast cancer cells by regulating MMP9 expression.First,scratch wound healing and transwell assays were performed in ZR-75-30 cells and MCF7 cells,and the results showed that DACH1 inhibited the invasion and metastasis of breast cancer cells.Secondly,RT-PCR and Western blot experiments showed that DACH1 significantly down-regulated the mRNA and protein levels of MMP9,and the gelatin zymography assay showed that the cell-secreted active MMP9 was significantly reduced.The luciferase reporter assay showed that DACH1 significantly inhibited the activity of the MMP9 promoter.The luciferase reporter assays using truncated and mutant MMP9 promoters and ChIP experiments showed that DACH1 inhibited MMP9 transcription through the NF-κB site and-79bp to-73bp AP-1 site.Next,CoIP and ChIP-reChIP assays showed that DACH1 acted on NF-κB and AP-1 binding sites to repress MMP9 expression by interacting with NF-κB p65 and AP-1 c-Jun.Finally,CoIP experiments showed that HDAC1 can interact with DACH1 and p65 respectively,and DACH1 can promote the interaction between p65 and HDAC1,and further increase the deacetylation of p65 by HDAC1,thereby inhibiting the transcriptional activity of p65.This study mainly demonstrated that DACH1 can inhibit the invasion and metastasis of breast cancer cells by inhibiting the transcription of MMP9.The regulatory mechanism is likely that DACH1 interacts with p65 and c-Jun,respectively,and acts on NF-κB and-79bp to-73bp AP-1 sites to inhibit MMP9 expression.Specifically,at the NF-κB site,DACH1 recruits HDAC1 to promote the deacetylation of p65,thereby inhibiting the transcriptional activity of p65.These studies have enriched the understanding of DACH1 inhibiting the tumor metastasis and provided new ideas for the treatment of tumor metastasis.