Cargnello R, Celio M R, Schwaller B, Gotzos V
Institute of Histology and General Embryology, University of Fribourg, Switzerland.
Biochim Biophys Acta. 1996 Oct 11;1313(3):201-8. doi: 10.1016/0167-4889(96)00090-0.
Calretinin is a Ca(2+)-binding protein of the EF-hand family which is expressed in colon adenocarcinomas and colon-derived tumor cell lines (e.g. WiDr), but is absent from normal human enterocytes. Its function has not as yet been elucidated, but some lines of evidence lead us to postulate its involvement in cell proliferation in these cells. In order to test whether calretinin is correlated with an undifferentiated, proliferating, or with a differentiated, state of cells, its expression was studied in the human colon adenocarcinoma clonal cell line HT29-18, which can be caused to differentiate into enterocyte-like cells by replacing glucose with galactose in the culture medium (glucose starvation differentiation). Treatment of HT29-18 cells with galactose led to a drop in the calretinin mRNA level and in protein expression as evidenced by immunocytochemical staining and Western blot analysis of cytosolic cell extracts. These results suggest that calretinin is present in HT29-18 cancer cells, mostly in those which are in the undifferentiated state. The possibility that calretinin is involved in maintaining the cells in an undifferentiated (cancerous) state is discussed.
钙视网膜蛋白是一种EF手型家族的钙结合蛋白，在结肠腺癌和源自结肠的肿瘤细胞系（如WiDr）中表达，但在正常人肠上皮细胞中不存在。其功能尚未阐明，但一些证据使我们推测它参与这些细胞的增殖。为了测试钙视网膜蛋白是否与细胞的未分化、增殖或分化状态相关，在人结肠腺癌克隆细胞系HT29-18中研究了其表达，该细胞系可通过在培养基中用半乳糖替代葡萄糖（葡萄糖饥饿分化）而分化为肠上皮样细胞。用半乳糖处理HT29-18细胞导致钙视网膜蛋白mRNA水平和蛋白表达下降，这通过免疫细胞化学染色和胞质细胞提取物的蛋白质印迹分析得以证实。这些结果表明钙视网膜蛋白存在于HT29-18癌细胞中，主要存在于未分化状态的细胞中。本文讨论了钙视网膜蛋白参与维持细胞处于未分化（癌性）状态的可能性。
