Methylation of the PTHrP P2 is a potential marker of breast cancer progression and might be used to evaluate the metastatic potential of breast tumors.
Switching of G-protein usage by the calcium-sensing receptor reverses its effect on parathyroid hormone-related protein secretion in normal versus malignant breast cells.
In light of these previous data, we have examined whether substrates of either reconstituted basement membrane or representative collagen components of the breast tumor stroma (type I, V and OF/LB) might (i) regulate the PTHrP promoter usage and mRNA splicing patterns, (ii) modulate quantitatively the extracellular release of immunoreactive PTHrP (iPTHrP), and (iii) affect the expression of PTHrP-R.
The presence of PTHrP and its receptor in normal breast epithelium and breast carcinomas demonstrates that most breast tumours are able to respond to PTHrP.
To establish whether the localization of the PTHrP antigen reflects protein synthesis and also to investigate the role of PTHrP in metastatic disease, as part of an ongoing study, we used in situ hybridization to study the localization of PTHrP mRNA in a retrospective series of primary breast tumors and their metastatic lesions.