Ahn Eun Hyun, Schroeder Joseph J
Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824-1224, USA.
Exp Biol Med (Maywood). 2002 May;227(5):345-53. doi: 10.1177/153537020222700507.
Complex dietary sphingolipids such as sphingomyelin and glycosphingolipids have been reported to inhibit development of colon cancer. This protective role may be the result of turnover to bioactive metabolites including sphingoid bases (sphingosine and sphinganine) and ceramide, which inhibit proliferation and stimulate apoptosis. The purpose of the present study was to investigate the effects of sphingoid bases and ceramides on the growth, death, and cell cycle of HT-29 and HCT-116 human colon cancer cells. The importance of the 4,5-trans double bond present in both sphingosine and C(2)-ceramide (a short chain analog of ceramide) was evaluated by comparing the effects of these lipids with those of sphinganine and C(2)-dihydroceramide (a short chain analog of dihydroceramide), which lack this structural feature. Sphingosine, sphinganine, and C(2)-ceramide inhibited growth and caused death of colon cancer cells in time- and concentration-dependent manners, whereas C(2)-dihydroceramide had no effect. These findings suggest that the 4,5-trans double bond is necessary for the inhibitory effects of C(2)-ceramide, but not for sphingoid bases. Evaluation of cellular morphology via fluorescence microscopy and quantitation of fragmented low-molecular weight DNA using the diphenylamine assay demonstrated that sphingoid bases and C(2)-ceramide cause chromatin and nuclear condensation as well as fragmentation of DNA, suggesting these lipids kill colon cancer cells by inducing apoptosis. Flow cytometric analyses confirmed that sphingoid bases and C(2)-ceramide increased the number of cells in the A(0) peak indicative of apoptosis and demonstrated that sphingoid bases arrest the cell cycle at G(2)/M phase and cause accumulation in the S phase. These findings establish that sphingoid bases and ceramide induce apoptosis in colon cancer cells and implicate them as potential mediators of the protective role of more complex dietary sphingolipids in colon carcinogenesis.
据报道，复杂的膳食鞘脂类物质，如鞘磷脂和糖鞘脂，可抑制结肠癌的发展。这种保护作用可能是其向生物活性代谢产物转化的结果，这些代谢产物包括鞘氨醇碱（鞘氨醇和二氢鞘氨醇）和神经酰胺，它们可抑制细胞增殖并刺激细胞凋亡。本研究的目的是探讨鞘氨醇碱和神经酰胺对HT-29和HCT-116人结肠癌细胞的生长、死亡及细胞周期的影响。通过比较鞘氨醇和C(2)-神经酰胺（神经酰胺的短链类似物）与缺乏该结构特征的二氢鞘氨醇和C(2)-二氢神经酰胺（二氢神经酰胺的短链类似物）的作用，评估了鞘氨醇和C(2)-神经酰胺中存在的4,5-反式双键的重要性。鞘氨醇、二氢鞘氨醇和C(2)-神经酰胺以时间和浓度依赖性方式抑制结肠癌细胞生长并导致其死亡，而C(2)-二氢神经酰胺则无此作用。这些发现表明，4,5-反式双键对于C(2)-神经酰胺的抑制作用是必需的，但对于鞘氨醇碱则不是。通过荧光显微镜评估细胞形态，并使用二苯胺测定法定量低分子量DNA片段化情况，结果表明鞘氨醇碱和C(2)-神经酰胺可导致染色质和核浓缩以及DNA片段化，提示这些脂质通过诱导细胞凋亡杀死结肠癌细胞。流式细胞术分析证实，鞘氨醇碱和C(2)-神经酰胺增加了指示细胞凋亡的A(0)峰中的细胞数量，并表明鞘氨醇碱使细胞周期停滞在G(2)/M期并导致S期积累。这些发现证实鞘氨醇碱和神经酰胺可诱导结肠癌细胞凋亡，并表明它们可能是更复杂的膳食鞘脂类物质在结肠癌发生过程中发挥保护作用的潜在介质。
