Age dependent variation of elastin and elastase in aorta and human breast cancers

Abstract

The elastin and elastase content of human aortas and human breast cancers was compared as a function of age and as a function of the degree of atherosclerosis (for aortas). It was confirmed that the cross-linked elastin content of aortas (expressed as desmosine per g dry weight) decreased with age and also with the degree of atherosclerosis. The elastase content of the same aortas increased exponentially with age (on a DNA basis) as well as with the degree of atherosclerosis. In human breast cancers both elastin and elastase increased linearly with age. The speed of increase for both elastin and elastase is nearly identical. These results indicate that although the steady increase of elastase in aortas with age may be causally related to the loss of the cross-linked elastin content, the concomitant decrease of the rate of elastin biosynthesis is probably a very important factor. In the presence of an adequate synthesis of elastin, the presence of increasing amounts of elastase is not bound to determine a steady loss of elastin. This is shown by the strongly correlated increase of elastin and elastase in breast cancers where an active biosynthesis probably replaces the elastin degraded by elastase. Cross-linked elastin may thus be synthesised at an advanced age and elastin cannot be considered as an inert body constituent but appears to have a measurable turover.