Identification of bone morphogenetic proteins and their receptors in human breast cancer cell lines: Importance of BMP2

The most frequent site of breast cancer metastasis is bone suggesting that some breast cancers express proteins that facilitate this process. We evaluated whether a highly metastatic breast cancer cell line, MDA-MB-231, and a less metastatic breast cancer cell line, MCF-7, contain bone morphogenetic proteins (BMP). Semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated that MDA and MCF-7 cells contain mRNAs for BMP receptors IA, IB and II. RT-PCR indicated the presence of mRNAs for BMPs 2 and 3 but not 4 and 7 in breast cells. Using a RT-PCR strategy with molecular beacons, we found that the mRNA for BMP2 in MDA cells was decreased by 75% after a sublethal dose of radiation. An ELISA using an antibody specific for BMP2 demonstrated that BMP2 protein was reduced after radiation of MDA cells. The mRNA for BMP2 was expressed to a lesser extent in MCF-7 cells than MDA cells and was not altered after radiation treatment of MCF-7 cells as demonstrated by molecular beacon RT-PCR. Recombinant human BMP2 decreased the proliferation of MDA cells to a greater extent than MCF-7 cells. These results expand the number of tissues that contain BMPs and demonstrate the effect of this signalling pathway of the growth state of these tissues.