We found that down-regulation of miRNA-200b promotes cancer cells survival during metastasis, and the homeless state of these cells resulted in decreased expression of miRNA-200b in the MCF-7 cell line.
Mapping the regulatory sequences controlling 93 breast cancer-associated miRNA genes leads to the identification of two functional promoters of the Hsa-mir-200b cluster, methylation of which is associated with metastasis or hormone receptor status in advanced breast cancer.
Tumor expression of miR-9 and miR-200b were confirmed using in situ hybridization, which also verified higher expression of these miRNAs in the distant metastases versus corresponding primary tumors.