Cell Cycle Arrest and Differential Gene Expression inHT-29 Cells Exposed to an Aqueous Garlic Extract

Abstract

Epidemiological data show an inverse correlation between garlic consumption and the risk for colon cancer. To examine this relationship, HT-29 human adenocarcinoma cells were cultured in the presence and absence of an aqueous garlic extract. Garlic treatment resulted in a fraction of cells detaching from the culture flasks. These cells remained viable. Flow cell cytometry showed that untreated cells exhibited a normal distribution among phases of the cell cycle, with 12% of cells at the G₂/M boundary. Of the garlic-treated cells remaining attached to the flask, 27% were present at the G₂/M boundary. Treated cells that detached from the flask were found almost exclusively (89%) at the G₂/M boundary. RNA fingerprinting and microarray analysis showed that expression of the gene for menin was twice as high in control cells as in detached treated cells. In contrast, expression of genes for epidermal growth factor receptor and integrin-α₆ was nearly twice as high in detached treated cells as in control cells. These changes in gene expression were consistent with an arrest of the cell cycle at the G₂/M boundary. Garlic=s arrest of the cell cycle in human adenocarcinoma cells may explain in part its anticarcinogenic properties.