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Background: Death domain-associated protein (DAXX) is a tumor suppressor and its loss has been found in a variety of cancer types. Dysregulation of DAXX is strongly correlated with cancer metastasis. However, the role and functions of DAXX in colorectal cancer (CRC) metastasis are not fully understood. Methods: We validated the mRNA and protein expression of DAXX in CRC specimens and CRC cell lines using real-time reverse transcription-PCR and Western blot, respectively. The overexpression plasmids of ZEB1 and E-cadherin and the siRNAs for DAXX and ZEB1 knockdown were constructed to study the impact of these factors on cells. Wound-healing assay and Transwell assay were performed to examine the cell motility and cell migration and invasion abilities, respectively. Luciferase assay was performed to assess the E-cadherin promoter activity. Immunoprecipitation assay was performed to investigate the interaction between proteins. The rescue experiment was carried out to verify whether the effect of DAXX on E-cadherin expression is depended on ZEB1. Results: DAXX expression was lower in liver metastases than in primary colon cancer tissues. Our results demonstrated that DAXX directly interacted with ZEB1 and suppressed its inhibitory effect on promoter activity of E-cadherin through a ZEB1-dependent manner, and thus suppresses the cell motility, migration, and invasion of CRC cell lines. Conclusion: In sum, these findings supported that the loss of DAXX is associated with cancer cell metastases in CRC. ZEB1-mediated transcriptional suppression of E-cadherin is a possible mechanism. DAXX/ZEB-1 pathway could be a potential therapeutic target for preventing cancer metastasis in CRC.

Fascin actin-bundling protein 1 (FSCN1), an actin-bundling protein associated with cell migration and invasion, is highly expressed in various tumor tissues. FSCN1 has also been reported to be a marker of increased invasive potential in cervical cancers. However, the functions of FSCN1 are still not fully understood in cervical cancers. Here, the gene expression profile of HeLa cells transfected with FSCN1 shRNA (shFSCN1) was compared with that of cells transfected with empty vector (shCtrl). The results showed that shFSCN1 extensively affected the transcription level of 5,043 genes in HeLa cells. In particular, Gene Ontology (GO) analysis showed that a large number of upregulated genes were annotated with terms including transcription regulation and DNA binding. The downregulated genes were enriched in some cancer pathways, including angiogenesis and cell adhesion. qPCR validation confirmed that FSCN1 knockdown significantly affected the expression of selected genes in HeLa cells either negatively or positively. Expression analysis in TCGA (The Cancer Genome Atlas) revealed that FSCN1 had negative correlations with several transcription factors and a positive correlation with an angiogenic factor (angiopoietin like 4, ANGPTL4) in cervical tumor tissue. In particular, validation by Western blotting showed that FSCN1 knockdown decreased the protein level of ANGPTL4. Our results demonstrated that FSCN1 is not only an actin-binding protein but also a transcriptional regulator and an angiogenic factor in cervical cancer. Thus, our study provides important insights for further study on the regulatory mechanism of FSCN1 in cervical cancer.

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