In addition to those cancers for which a causative role for aberrant ALK activity is well validated, more circumstantial links implicate the full-length, normal ALK receptor in the genesis of other malignancies - including glioblastoma and breast cancer - via a mechanism of receptor activation involving autocrine and/or paracrine growth loops with the reported ALK ligands, pleiotrophin and midkine.
Expression of the angiogenic factors vascular endothelial cell growth factor, acidic and basic fibroblast growth factor, tumor growth factor beta-1, platelet-derived endothelial cell growth factor, placenta growth factor, and pleiotrophin in human primary breast cancer and its relation to angiogenesis.
The mutant Ptn cDNA was then introduced into human breast cancer MDA-MB-231 cells, and clonal lines that stably express the mutant Ptn cDNA were selected.
Finally, we propose that understanding the functions of PTN and its hormonal regulation can lead to the development of novel therapeutic strategies for breast cancer.
Previously we reported the purification of the heparin-binding growth factor pleiotrophin (PTN) from supernatants of the human breast cancer cell line MDA-MB-231.