Harper K D, Iozzo R V, Haddad J G
Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia.
Metabolism. 1989 Nov;38(11):1062-9. doi: 10.1016/0026-0495(89)90041-3.
Human colon carcinoma (HT-29) cells were examined for their capacity to bind and respond to 1,25-dihydroxycholecalciferol [1,25-(OH)2D3]. These cells are known to differentiate and increase their population doubling time when galactose is substituted for glucose in their media. High-affinity and specific binding of 1,25-(OH)2[3H]D3 was observed in extracts of these cells grown in glucose. The binder sedimented in sucrose gradients and eluted from DEAE-cellulose columns in a manner indistinguishable from rabbit intestinal 1,25-(OH)2D3-receptor. Smaller amounts of this binder were seen in HT-29 cells grown in galactose. Both glucose-fed and galactose-fed cells exhibited a dose-dependent decrease in growth rate on exposure to 10(-12) to 10(-6) mol/L 1,25-(OH)2D3. Ultrastructural examination of galactose-fed and glucose + 1,25-(OH)2D3-treated cells showed enterocytic differentiation and features that were not distinguishable between these groups. Sucrase activity was higher in galactose-fed cells and did not change with 1,25-(OH)2D3 treatment. However, the lower sucrase activity in glucose-fed cells increased after exposure to 10(-8) mol/L 1,25-(OH)2D3. These results indicate receptor content and bioresponsivity to 1,25-(OH)2D3 in a human enterocytic cell line, suggesting that it will be a useful model for the study of the mechanisms of action of this sterol.
对人结肠癌细胞（HT - 29）结合和响应1,25 - 二羟胆钙化醇[1,25 - (OH)₂D₃]的能力进行了检测。已知当这些细胞培养基中的葡萄糖被半乳糖替代时，它们会发生分化并延长群体倍增时间。在以葡萄糖培养的这些细胞提取物中观察到了1,25 - (OH)₂[³H]D₃的高亲和力和特异性结合。该结合蛋白在蔗糖梯度中沉降，并从DEAE - 纤维素柱上洗脱，其方式与兔肠道1,25 - (OH)₂D₃受体无法区分。在以半乳糖培养的HT - 29细胞中，这种结合蛋白的量较少。用10⁻¹²至10⁻⁶mol/L的1,25 - (OH)₂D₃处理时，以葡萄糖培养和以半乳糖培养的细胞均表现出剂量依赖性的生长速率下降。对半乳糖培养和葡萄糖 + 1,25 - (OH)₂D₃处理的细胞进行超微结构检查，结果显示有肠上皮细胞分化，且两组之间无明显差异。半乳糖培养的细胞中蔗糖酶活性较高，并且1,25 - (OH)₂D₃处理后没有变化。然而，以葡萄糖培养的细胞中较低的蔗糖酶活性在暴露于10⁻⁸mol/L的1,25 - (OH)₂D₃后有所增加。这些结果表明，在一种人肠上皮细胞系中存在1,25 - (OH)₂D₃的受体含量和生物反应性，这表明它将是研究这种固醇作用机制的有用模型。
