Expression of homeobox gene transcripts in trophoblastic cells.

OBJECTIVE: This study was conducted to examine the dynamics of homeobox gene expression in the differentiation of trophoblasts as a key to the understanding of the regulatory mechanisms that are involved in placental development.

STUDY DESIGN: Expression of homeobox genes was examined in primary trophoblastic cells and in the BeWo choriocarcinoma model cell lines by molecular and immunocytochemistry techniques.

RESULTS: We demonstrated the expression of 3 homeobox genes (HOX B6, HOX C6, and HOX A11) in primary trophoblastic cells. BeWo cells showed an expression pattern similar to that of the primary cell lines. In both primary trophoblasts and BeWo cells, the HOX A11 gene, but not the HOX B6 or HOX C6 genes, were found to down-regulate with differentiation from single- to multinucleate giant cells.

CONCLUSION: This study demonstrates a novel expression pattern for HOX A11 gene in trophoblastic differentiation and suggests that the down-regulation of HOX A11 may be necessary for the differentiation of cytotrophoblasts into syncytiotrophoblasts.