Four peptide hormones decrease the number of human breast adenocarcinoma cells.

Background: A family of six hormones, i.e. atrial natriuretic peptide, brain natriuretic peptide, C-natriuretic peptide, long-acting natriuretic peptide, vessel dilator, and kaliuretic peptide's main known biologic properties are sodium and water excreting and blood pressure lowering.
Methods and Materials: These six hormones, each at their 1-microm concentrations, were evaluated for their ability to decrease the number and/or proliferation of breast adenocarcinoma cells in culture for 24, 48, 72, and 96 h.
Results: Within 24 h, vessel dilator, long-acting natriuretic peptide, kaliuretic peptide, atrial natriuretic peptide and 8-bromo-cyclic GMP, a cell-permeable analogue of their intracellular mediator cyclic GMP (each at 1 microm), decreased the number of breast adenocarcinoma cells 60%, 31%, 27%, 40%, and 31%, respectively. There was no proliferation in the 3 days following this decrease in breast adenocarcinoma cell number. These same hormones decreased DNA synthesis 69% to 85% (P < 0.001). Brain natriuretic peptide and CNP did not decrease the number of breast adenocarcinoma cells or inhibit their DNA synthesis. Vessel dilator, long-acting natriuretic peptide, kaliuretic peptide and 8-bromo-cyclic GMP (each at 1 microM) decreased the number of cells in the S phase of the cell cycle by 62%, 33%, 50%, and 39%, respectively (all P < 0.05). Natriuretic peptide receptors-A and -C were present in the breast adenocarcinoma cells.
Conclusions: Four peptide hormones significantly decrease the number of human breast adenocarcinoma cells within 24 h and inhibit the proliferation of these cells for at least 96 h. Their mechanism of doing so involves inhibition of DNA synthesis and a decrease in cells in the S phase of the cell cycle mediated in part by cyclic GMP.