Abrahamse S L, Pool-Zobel B L, Rechkemmer G
Institute of Nutritional Physiology, Federal Research Centre for Nutrition, Karlsruhe, Germany.
Carcinogenesis. 1999 Apr;20(4):629-34. doi: 10.1093/carcin/20.4.629.
Short chain fatty acids (SCFA) are considered to be beneficial fermentation products in the gut by exerting trophic effects in non-transformed colon cells and by slowing proliferation and enhancing differentiation in colonic tumour cells. We have studied the further effects of SCFA on cellular events of early carcinogenesis, genotoxicity and cytotoxicity in rat distal colon cells. Cytotoxicity was assessed by measuring trypan blue exclusion and by determining the H2O2-induced changes in intracellular calcium concentration ([Ca2+]i) using a fluorospectrophotometer and the calcium-sensitive fluorescent dye Fura-2. The microgel electrophoresis technique (COMET assay) was used to assess oxidative DNA damage. Individual SCFA and physiological SCFA mixtures were investigated for their potential to prevent DNA and cell damage induced by H2O2. For this, freshly isolated colon cells were treated with H2O2 (100-500 microM) and 6.25 mM SCFA. We have found 100-500 microM H2O2 to cause a fast initial increase in [Ca2+]i, whereafter the levels gradually further increased. Addition of SCFA did not affect [Ca2+]i nor did it reduce the H2O2-induced increase in [Ca2+]i. Butyrate and acetate were able to reduce the induction of DNA damage by 100, 200 and 500 microM H2O2, respectively. In contrast, i-butyrate and propionate were ineffective. The degree of reduction of DNA damage for the two protective SCFA was similar. Physiological mixtures containing acetate, propionate and butyrate in ratios of 41:21:38 or 75:15:10 that are expected to arise in the colon after fermentation of resistant starches and pectin, respectively, did not show significant antigenotoxic effects. The major difference between butyrate and acetate, on one hand, and i-butyrate and propionate, on the other hand, is that the former compounds are utilized best as energy sources by the colon cells. Therefore, our results on antigenotoxicity coupled with the findings on [Ca2+]i homeostasis indicate that molecular effects on the energy system render these non-transformed, freshly isolated colon cells to be less susceptible to H2O2.
短链脂肪酸（SCFA）被认为是肠道中有益的发酵产物，它对未转化的结肠细胞具有营养作用，能减缓结肠肿瘤细胞的增殖并增强其分化。我们研究了SCFA对大鼠远端结肠细胞早期致癌过程、遗传毒性和细胞毒性等细胞事件的进一步影响。通过测量台盼蓝排斥率以及使用荧光分光光度计和钙敏感荧光染料Fura - 2测定H2O2诱导的细胞内钙浓度（[Ca2+]i）变化来评估细胞毒性。采用微凝胶电泳技术（彗星试验）评估氧化性DNA损伤。研究了单个SCFA和生理性SCFA混合物预防H2O2诱导的DNA和细胞损伤的潜力。为此，将新鲜分离的结肠细胞用H2O2（100 - 500 microM）和6.25 mM SCFA处理。我们发现100 - 500 microM的H2O2会使[Ca2+]i迅速出现初始升高，随后水平逐渐进一步上升。添加SCFA既不影响[Ca2+]i，也不降低H2O2诱导的[Ca2+]i升高。丁酸盐和乙酸盐能够分别降低100、200和500 microM H2O2诱导的DNA损伤。相比之下，异丁酸盐和丙酸盐则无效。两种具有保护作用的SCFA对DNA损伤的降低程度相似。分别在抗性淀粉和果胶发酵后预计会在结肠中出现的、乙酸盐、丙酸盐和丁酸盐比例为41:21:38或75:15:10的生理性混合物，未显示出显著的抗遗传毒性作用。一方面，丁酸盐和乙酸盐与另一方面的异丁酸盐和丙酸盐之间的主要区别在于，前两种化合物是结肠细胞最佳的能量来源。因此，我们关于抗遗传毒性的结果以及关于[Ca2+]i稳态的发现表明，对能量系统的分子作用使这些未转化的新鲜分离结肠细胞对H2O2的敏感性降低。
