We’ve focused on establishing the significance in the cell surface hyaluronan receptor CD44 in underpinning the preferential metastasis of breast cancer cells to bone. In prior in vitro research, we demonstrated that depletion of CD44 expression in breast cancer cells attenuates their adhesion to bone marrow endothelial cells. Our recent experiments have also determined that the expression of CD44 is elevated within the bone homing breast cancer subline MDA231BO relative to that detected within the parental MDA231 breast cancer cell line. Collectively these experiments suggest a physiological role for this receptor in advertising the entry of breast cancer cells into the bone microenvironment.
Strategies To further fully grasp the possible significance of CD44 signalling to breast cancer metastasis, we established a tetracycline regulated CD44 expression technique inside the minimally invasive, CD44 damaging MCF7F cell line. Removal of tetracycline from the development media resulted in time dependent increases in CD44 expression in MCF7F cells, advertising elevated cell invasion and migration selleck chemical responses along with potentiating the adhesion of MCF7F cells to BMECs. Subsequent microarray evaluation was performed employing this expression method to identify CD44HA regulated genes in breast cancer cells. Benefits The expression and activation of CD44 was linked with increased expression of a subset of genes implicated in metastasis which includes proteolytic enzymes, growth components and cytoskeletal proteins. Interestingly, the cysteine protease cathepsin K and the matrix metalloprotease MT1MMP had been identified as CD44HA regulated genes.
These proteases target collagen I, a significant full report element in the bone matrix whose degradation is actually a big consequence of osteolytic metastasis of breast cancer. Constant with their respective metastatic potential, immunoblotting and ELISA primarily based experiments have confirmed that the expression of MT1MMP and cathepsin K are each elevated in the MDA231BO bone homing cells relative to the parental MDA231 cells. Additionally, the expression of cathepsin K and MT1MMP within the MDA231BO cells was substantially decreased upon RNAi mediated suppression of CD44. Quantitative real time PCR, immunoblotting and ELISA based experiments have also demonstrated that the transcript and protein expression of cathepsin K and MT1MMP improve in response to CD44HA signalling within a panel of CD44 expressing breast cancer cell lines.
Presently, we’re investigating the mechanistic basis underpinning the transcription of these target genes in breast cancer cells, figuring out the functional significance of their overexpression in facilitating breast cancer cells to degrade a collagen I matrix, and applying the MDA231BO cell line to figure out the in vivo significance of CD44 expression to osteolytic metastasis.