Objective   To analyze the DKK1 expression in breast cancer cell line MDA-MB-231 and examine its effect on the migration and invasion of the cell line.

  Method   DKK1 expression in the breast cancer tissues was detected immunohistochemically, and DKK1 distribution in the breast cancer cells was observed using immunofluorescence. Western blot was used to investigate DKK1 expression in breast cancer tissues and their matched normal breast tissues. A eukaryotic expression vector of DKK1 was constructed and transfected into MDA231 cell line. The migration and invasion ability of the cells were observed through scratch assay and Boyden chamber, respectively.

  Results   Immunohistochemical staining showed that DKK1 in the transfected lymph node or non-lymph node was highly expressed in the breast cancer tissues (P < 0.05). The positive DKK1 expression in lymph node metastasis was less significant than those in non-lymph node transfected cells. Immunofluorescence localization results showed a remarkable bright red granular fluorescence in the cytoplasm of the MDA231 cell line. Western blot analysis showed that the DKK1 protein expression in carcinoma tissues were obviously higher than that in matched normal breast tissues. The migration and invasion ability of DKK1- overexpressed MDA231 cell was lower than those of MDA231 cell transfected with pCMV-Tag-2b empty vector.

  Conclusion   Negative correlation was found between DKK1 expression and the migration and invasion ability in breast cancer cells.