Growth-inhibitory effects of a mineralized extract from the red marine algae, Lithothamnion calcareum, on Ca-sensitive and Ca-resistant human colon carcinoma cells

Proliferation and differentiation were assessed in a series of human colon carcinoma cell lines in response to a mineral-rich extract derived from the red marine algae, Lithothamnion calcareum. The extract contains 12% Ca²⁺, 1% Mg²⁺, and detectable amounts of 72 trace elements, but essentially no organic material. The red algae extract was as effective as inorganic Ca²⁺ alone in suppressing growth and inducing differentiation of colon carcinoma cells that are responsive to a physiological level of extracellular Ca²⁺ (1.4 mM). However, with cells that are resistant to Ca²⁺ alone, the extract was still able to reduce proliferation and stimulate differentiation.