Leschelle X, Delpal S, Goubern M, Blottière H M, Blachier F
Laboratoire de Nutrition et Sécurité Alimentaire, Institut National de la Recherche Agronomique, Jouy-en-Josas, France.
Eur J Biochem. 2000 Nov;267(21):6435-42. doi: 10.1046/j.1432-1327.2000.01731.x.
Butyrate is a short chain fatty acid (SCFA) produced by bacterial fermentation of dietary fibers in the colon lumen which severely affects the proliferation of colon cancer cells in in vitro experiments. Although butyrate is able to interfere with numerous cellular targets including cell cycle regulator expression, little is known about butyrate metabolism and its possible involvement in its effect upon colon carcinoma cell growth. In this study, we found that HT-29 Glc-/+ cells strongly accumulated and oxidized sodium butyrate without producing ketone bodies, nor modifying oxygen consumption nor mitochondrial ATP synthesis. HT-29 cells accumulated and oxidized sodium acetate at a higher level than butyrate. However, sodium butyrate, but not sodium acetate, reduced cell growth and increased the expression of the cell cycle effector cyclin D3 and the inhibitor of the G1/S cdk-cyclin complexes p21/WAF1/Cip1, demonstrating that butyrate metabolism downstream of acetyl-CoA synthesis is not required for the growth-restraining effect of this SCFA. Furthermore, HT-29 cells modestly incorporated the 14C-labelled carbon from sodium butyrate into cellular triacylglycerols and phospholipids. This incorporation was greatly increased when D-glucose was present in the incubation medium, corresponding to the capacity of hexose to circulate in the pentose phosphate pathway allowing NADPH synthesis required for lipogenesis. Interestingly, when HT-29 cells were cultured in the presence of sodium butyrate, their capacity to incorporate 14C-labelled sodium butyrate into triacylglycerols and phospholipids was increased more than twofold. In such experimental conditions, HT-29 cells when observed under an electronic microscope, were found to be characterized by an accumulation of lipid droplets in the cytosol. Our data strongly suggest that butyrate acts upon colon carcinoma cells upstream of acetyl-CoA synthesis. In contrast, the metabolism downstream of acetyl-CoA [i.e. oxidation in the tricarboxylic acid (TCA) cycle and lipid synthesis] likely acts as a regulator of butyrate intracellular concentration.
丁酸盐是一种短链脂肪酸（SCFA），由结肠腔中膳食纤维的细菌发酵产生，在体外实验中它会严重影响结肠癌细胞的增殖。尽管丁酸盐能够干扰众多细胞靶点，包括细胞周期调节因子的表达，但关于丁酸盐代谢及其对结肠癌细胞生长影响的可能作用知之甚少。在本研究中，我们发现HT - 29 Glc - / +细胞强烈积累并氧化丁酸钠，既不产生酮体，也不改变氧气消耗和线粒体ATP合成。HT - 29细胞积累和氧化醋酸钠的水平高于丁酸盐。然而，丁酸钠而非醋酸钠会降低细胞生长，并增加细胞周期效应因子细胞周期蛋白D3以及G1/S细胞周期蛋白依赖性激酶 - 细胞周期蛋白复合物抑制剂p21/WAF1/Cip1的表达，这表明对于这种短链脂肪酸的生长抑制作用而言，乙酰辅酶A合成下游的丁酸盐代谢并非必需。此外，HT - 29细胞适度地将丁酸钠中14C标记的碳掺入细胞三酰甘油和磷脂中。当孵育培养基中存在D - 葡萄糖时，这种掺入显著增加，这与己糖在磷酸戊糖途径中循环的能力相对应，该途径可产生脂肪生成所需的NADPH。有趣的是，当HT - 29细胞在丁酸钠存在的情况下培养时，它们将14C标记的丁酸钠掺入三酰甘油和磷脂中的能力增加了两倍多。在这种实验条件下，在电子显微镜下观察时，发现HT - 29细胞的特征是胞质中存在脂滴积累。我们的数据强烈表明，丁酸盐在乙酰辅酶A合成的上游作用于结肠癌细胞。相反，乙酰辅酶A下游的代谢（即三羧酸（TCA）循环中的氧化和脂质合成）可能作为丁酸盐细胞内浓度的调节剂。
