In the biosynthesis of adrenomedullin (AM), an intermediate form, AM(1-52)-glycine-COOH (iAM), is cleaved from proAM and subsequently processed to a biologically active mature form, AM(1-52)-NH2 (mAM), by enzymatic amidation. We recently reported that immunoreactive AM in human plasma consists of mAM and iAM. To clarify the pathophysiological roles of mAM and iAM in heart failure, we established an assay method to specifically detect mAM, and we determined the plasma concentrations of mAM and iAM in 68 patients with congestive heart failure (CHF). The plasma mAM concentrations of the CHF patients classified as being class I or II of New York Heart Association (NYHA) functional classification were significantly greater than those of the 28 healthy controls, and a further increase was noted in the class III or IV patients. Similar increases in plasma iAM were also observed in these patients compared with controls. The increased plasma mAM and iAM in 12 patients with exacerbated CHF were significantly reduced by treatment of their CHF for 7 days. In addition, the plasma concentrations of both mAM and iAM were significantly correlated with pulmonary capillary wedge pressure, pulmonary artery pressure, right atrial pressure, cardiothoracic ratio, heart rate, and the plasma concentrations of atrial and brain natriuretic peptides in the CHF patients. Thus the plasma concentrations of both mAM and iAM were increased progressively in proportion to the severity of CHF. These results suggest that, though the role of iAM remains to be clarified, mAM acts against the further deterioration of heart failure in patients with CHF.

Progesterone and progestins have been demonstrated to enhance breast cancer cell migration, although the mechanisms are still not fully understood. The protease-activated receptors (PARs) are a family of membrane receptors that are activated by serine proteases in the blood coagulation cascade. PAR1 (F2R) has been reported to be involved in cancer cell migration and overexpressed in breast cancer. We herein demonstrate that PAR1 mRNA and protein are upregulated by progesterone treatment of the breast cancer cell lines ZR-75 and T47D. This regulation is dependent on the progesterone receptor (PR) but does not require PR phosphorylation at serine 294 or the PR proline-rich region mPRO. The increase in PAR1 mRNA was transient, being present at 3 h and returning to basal levels at 18 h. The addition of a PAR1-activating peptide (aPAR1) to cells treated with progesterone resulted in an increase in focal adhesion (FA) formation as measured by the cellular levels of phosphorylated FA kinase. The combined but not individual treatment of progesterone and aPAR1 also markedly increased stress fiber formation and the migratory capacity of breast cancer cells. In agreement with in vitro findings, data mining from the Oncomine platform revealed that PAR1 expression was significantly upregulated in PR-positive breast tumors. Our observation that PAR1 expression and signal transduction are modulated by progesterone provides new insight into how the progestin component in hormone therapies increases the risk of breast cancer in postmenopausal women.