Growth Rates of a Human Colon Adenocarcinoma Cell Line are Regulated by the Milk Protein Alpha-Lactalbumin

Abstract

The whey protein a-lactalbumin, derived from human milk, has been shown to inhibit proliferation of mammary epithelial cells and rat kidney cells. We have shown that bovine a-lactalbumin also has antiproliferative effects in human colon adenocarcinoma cell lines. During a 5-day dose-dependent growth study, bovine a-lactalbumin was added to Caco-2 or HT-29 monolayers in amounts from 5 to 35 µg/mL. Low concentrations of a-lactalbumin (10-25 µg/mL) stimulated growth during the first 3 to 4 days. After growing for 4 days, proliferation ceased and viable cell numbers decreased dramatically in the a-lactalbumin-treated cultures, suggesting a delayed initiation of apoptosis. This experiment demonstrates the acute bioactive effects of small concentrations of a-lactalbumin, compared with the high concentrations of other proteins in the media. These results suggest that a-lactalbumin in milk may promote health by inhibiting growth of potential cancer cells. Further studies will identify the role of calcium in the bioactivity of a-lactalbumin