Stearate preferentially induces apoptosis in human breast cancer cells.

Stearic acid (stearate) is an 18-carbon saturated fatty acid that has been shown to inhibit invasion and proliferation and induce apoptosis in various human cell types. The specificity of stearate-induced apoptosis for cancerous versus noncancerous breast cells has not been examined, and the mechanism underlying stearate-induced apoptosis is unknown. Morphological analysis, cell viability, and caspase-3 activity assays demonstrated that stearate activated apoptosis preferentially in cancerous breast cells in a time- and dose-dependent manner. Inhibition of de novo diacylgycerol synthesis or protein kinase C (PKC) blocked stearate-induced caspase-3 activity, indicating the involvement of a novel or classical PKC isozyme. To our knowledge this is the first study showing that stearate induces apoptosis preferentially in breast cancer cells and implicates protein kinase C in the signaling cascade. These results raise the possibility of dietary stearate having a beneficial role in the prevention or treatment of breast cancer.

Abdominal obesity, insulin resistance, and colon carcinogenesis are increased in mutant mice lacking gastrin gene expression.

BACKGROUND: The authors recently reported that gastrin gene knockout (GAS-KO) mice had an increased risk for colon carcinogenesis in response to azoxymethane (AOM) compared with their wild type (WT) littermates. In the current report, the authors discuss the predisposition of GAS-KO mice to develop obesity and metabolic hormonal changes that may contribute to their increased risk of colon carcinogenesis. METHODS: The weight and deposition of fat was monitored in the mice over a 14 month period, using magnetic resonance imaging and nuclear magnetic resonance techniques. Changes in plasma concentrations of ghrelin, leptin, insulin, and glucose were assessed using radioimmunoassay analysis and enzyme-linked immunosorbent assays. Preneoplastic markers of colon carcinogenesis (aberrant crypt foci [ACFs]), in response to AOM, were measured in a subset of obese versus lean GAS-KO mice and were compared with the markers in WT mice. RESULTS: Increases in visceral adiposity were evident by age 2 months in GAS-KO mice, resulting in macroscopic obesity by age 7 months. Hyperinsulinemia and insulin:glucose ratios were increased significantly in GAS-KO mice as young as 1 month and preceded alterations in nonfasting leptin and ghrelin levels. The number of ACFs per mouse colon were increased significantly in the following order: obese GAS-KO mice > lean GAS-KO mice > WT mice. Fasting plasma insulin levels were 0.88 +/- 0.1 ng/mL, 1.45 +/- 0.3, and 2.76 +/- 0.9 ng/mL in the WT, GAS-KO lean, and GAS-KO obese mice, respectively. CONCLUSIONS: The current results suggest the novel possibility that loss of amidated gastrins may increase adipogenesis, hyperinsulinemia, and colon carcinogenesis in GAS-KO mice. The increase in colon carcinogenesis may be due in part to hyperinsulinemia, increased obesity, and other associated hormone changes that were measured in GAS-KO mice.