PARATHYROID HORMONE-RELATED PEPTIDE AND 8701-BC BREAST-CANCER CELL-GROWTH AND INVASION IN-VITRO - EVIDENCE FOR GROWTH-INHIBITING AND INVASION-PROMOTING EFFECTS

It has been previously reported that 8701-BC cells, derived from a pri mary carcinoma of the breast, constitutively express parathyroid hormo ne-related peptide (PTHrP) gene and that N-terminal PTHrP immunoreacti vity can be found in cell medium. Here we have firstly measured immuno reactive PTHrP in 8701-BC cell medium using antibodies raised against midregion and C-terminal fragments, and also demonstrated the expressi on of PTH/PTHrP receptor by 8701-BC cells; Secondly, we have examined the role, if any, elicited by diverse PTHrP domains on 8701-BC cell pr oliferation, and invasive behaviour in vitro related to production of extracellular proteolytic enzymes. Our data show that PTHrP [1-34], an d, to a minor extent, [67-86] and [107-139], are anti-mitogenic but 'i nvadogenic' for 8701-BC cells, and suggest that diverse enzymatic acti vities may contribute to cell invasion in response to different PTHrP fragments. In light of the present data on a chemoattractive role for PTHrP in vitro, we hypothesize that this protein might intervene in lo cal control of the invasive process in breast carcinoma.