Secreted frizzled-related proteins (sFRPs) are secreted glycoproteins involved 
in neoplastic growth. Four hormones synthesized in the heart, namely vessel 
dilator, atrial natriuretic peptide (ANP), kaliuretic peptide (KP) and 
long-acting natriuretic peptide (LANP), have anticancer effects both in vitro 
and in vivo. These heart hormones were evaluated for their ability to inhibit 
sFRP-3, which is associated with tumor invasiveness, in human pancreatic cancer, 
colorectal cancer and renal adenocarcinoma cell lines. Vessel dilator, KP, ANP 
and LANP maximally reduced the concentration of sFRP-3 by 83%, 83%, 84% and 83%, 
respectively (each at P<0.0001), in the human colorectal adenocarcinoma cells. 
In the human pancreatic carcinoma cells, the concentration of sFRP-3 was 
maximally reduced by 77%, 77%, 77% and 78% (each at P<0.0001) secondary to 
treatment with vessel dilator, KP, ANP and LANP, respectively. In the human 
renal adenocarcinoma cells, the sFRP-3 was maximally reduced by vessel dilator, 
KP, ANP and LANP by 68%, 66%, 68% and 66% (each at P<0.0001), respectively. The 
results indicate that these four cardiac hormones are significant inhibitors (up 
to 84%) of sFRP-3 in a variety of human cancer cells. Furthermore, these data 
suggest that the metabolic targeting of sFRP-3 by the cardiac hormones 
contributes to their anti-cancer mechanism(s) of action.