n-3多不饱和脂肪酸对人结肠癌细胞增殖与凋亡的影响

目的探讨n-3多不饱和脂肪酸（n-3PUFA）对人结肠癌细胞HT．29的作用及其机制。方法应用MTT比色法、细胞的形态学观察（Hochest33258染色）、DNA凝胶电泳、流式细胞技术检测二十二碳六烯酸（DHA）对HT．29增殖和凋亡的影响：气相色谱分析的方法检测DHA对HT-29细胞n-3PUFA和n．6PUFA含量及n-6／n-3PUFA比例的影响。结果DHA在体外对HT．29有明显的增殖抑制作用,10、20、40和80mg儿DHA作用24h时的细胞增殖抑制率分别为16．8％、24．7％、50．0％和60．1％。40mg／LDHA作用24、48和72h的细胞增殖抑制率分别为50．0％、69．9％和77．0％：呈现明显的剂量和时间效应关系。荧光染色可观察到细胞核染色质浓集,核浓缩核碎裂．并出现典型的凋亡小体：DNA凝胶电泳呈现特征性的梯形条带（DNALadder）：流式细胞仪检测显示经DHA处理后HT-29DNA合成前期（G,期）细胞比例较对照组增加（72．1％比51．3％）,DNA合成期（S期）细胞比例明显减少（19．9％比38．9％）,细胞呈现明显的G,期阻滞;气相色谱分析显示．DHA可以降低HT-29细胞内n-6PUFA而提高n-3PUFA含量,降低n-6／n-3PUFA比率。结论n-3PUFA通过抑制细胞增殖和诱导细胞凋亡来阻遏结肠癌细胞的生长．这种作用的机制可能为降低了细胞的n-6／n-3PUFA的比例。

Effect of n-3 polyunsaturated fatty acids on proliferation and apoptosis of human colon cancer cell

Objective To investigate the effects of n-3 polyunsaturated fatty acids（n-3PUFA） on human colorectal cancer cell line HT-29 and associated mechanism. Methods The effects of docosahexaenoic acid （DHA） on the proliferation and apoptosis on HT-29 human colorectal cancer cells were evaluated by MTT assay, cell morphology （Hoechst33258 dyeing）, DNA gel electrophoresis, and flow cytometry. The content of n-6PUFA and n-3PUFA of the treated cells and the ratio of n-6/n-3PUFA were analyzed by chromatography. Results I）HA effectively inhibited HT-29 cell proliferation in a dose- and time-dependent manner. The proliferative inhibition rates of HT-29 cells treated with 10, 20, 40, and 80 mg/L DHA for 24 hours were 16.8%, 24.7%, 50.0%, and 60.1%, respectively, while the inhibition rates were 50.0%, 69.9%, and 77.0% respectively when HT-29 cells were treated with 40 mg/L DHA for 24, 48, and 72 hours. The typical apoptotic mo,＇phologie changes of HT-29 cells could be observed, including chromatin margination, nuclear condensation and apoptotic bodies. Gel electrophoresis of DNA degradation displayed typical DNA ladder fragments. HT-29 cells treated with DHA were arrested in G1 phase and the proportion of HT-29 cells in G1 phase increased compared with that of the control group （72.1% vs. 51.3%） while the proportion of the cells in S phase decreased significantly （19.9% vs. 38.9%）. The content of n-6PUFA decreased, n-3PUFA content increased and the ratio of n-6/n-3PUFA lowered significantly in colorectal cancer ceils treated with DHA （P〈0.01）. Conclusions n-3PUFA can inhibit the growth of human colorectal cancer cells via inhibition of the proliferation and induction of apoptosis. These effects may be associated with decrease in n-6/n-3PUFA ratio.