Calcium and Growth in Aging and Cancer

Abstract

The effect of alteration of the calcium content of cells on longevity was studied in rotifers. In a low Ca medium, the animals lived longer than controls. Removal of Ca from the cells of the rotifer by Na citrate caused a marked increase in longevity. Expts. on the effect of starvation on longevity show that starvation increases longevity by extending the period of growth; the length of the growth period may condition longevity and cessation of growth may initiate the aging mechanism. Growth cessation is in fact a critical turning point in starting age changes. There is a sharply defined transition between ages of lines of rotifers that maintain and increase longevity or progressively reduce it. Lines of a parental age younger than that at which growth stops show progressively increased longevity and appear free of age change. All lines of parental age older than that at which growth stops show progressive reduction of mean life spans to the point of non-viability. If growth cessation is significant in aging and if a device involving Ca increase is an integral part of this system, the opposite situation should occur in cancer. Cancer is a youthful and vigorous tissue. It is markedly low in Ca; the ultrafilterable Ca fraction of a squamous cell carcinoma is sharply reduced on both an absolute and relative basis. It is suggested that the base-binding capacity of an organic fraction which binds Ca is changed in cancer. This binding complex may be situated in the cell cortex. It may be that an organic Ca-binding complex of the cortex is involved in the growth regulation of cells and at growth cessation this complex, which may be a protein, is changed so as to increase Ca-binding capacity. When the system changes so as to decrease Ca-binding, the state exists that is associated with cancer.