Iwata K, Kouttab N, Ogata H, Morgan J W, Maizel A L, Lasky S R
Roger Williams Medical Center, Experimental Pathology Section, Department of Pathology and Laboratory, Brown University School of Medicine, Providence, RI 02908, USA.
Exp Cell Res. 1996 May 25;225(1):143-50. doi: 10.1006/excr.1996.0165.
RWLeu4 is a chronic myelogenous leukemia cell line that is sensitive to the antiproliferative and differentiation-inducing actions of 1alpha,25(OH)2-vitamin D3 (VD3). The JMRD3 cell line is a VD3-resistant variant of RWLeu4 that was selected by continuous passage of RWLeu4 in the presence of VD3. The isolation of a spontaneous VD3-resistant variant suggests that phenotypically different cells exist within the RWLeu4 cell population. Therefore, single-cell clones of RWLeu4 cells were isolated and characterized. Four clonal cell populations that fall into three groups differing in response to the antiproliferative and differentiation-inducing actions of VD3 were examined. Surprisingly, the extent of response of the clones to VD3 does not show a correlation with the basal level of the vitamin D receptor (VDR). RWLeu4-3 and RWLeu4-4 are the clones most sensitive to the antiproliferative actions of VD3 (ED50 approximately equal to 1 nM); however, RWLeu4-3 expresses basal levels of VDRs similar to those found in the parental cells and the RWLeu4-2 clone, while in RWLeu4-4, VD3 binding and VDR protein are below the limits of detection. Furthermore, RWLeu4-10 expresses the highest basal level of VDR protein but is relatively resistant to the antiproliferative actions of VD3 (ED50 > or = 30 nM). Like JMRD3, RWLeu4-10 is still capable of differentiating in response to VD3, as judged by the induction of biochemical processes and cell-surface antigen expression. Although VD3 treatment increases VDR protein levels and DNA-binding activity in all clones, altered DNA-protein complexes are detected in RWLeu4-4. Our results suggest that sensitivity to the antiproliferative and differentiation-inducing actions of VD3 is not dependent solely upon the level of VDR expressed, but may also require posttranslational modification of the VDR or complex interactions with other nuclear transcription factors.
RWLeu4是一种慢性粒细胞白血病细胞系，对1α,25(OH)2 - 维生素D3（VD3）的抗增殖和诱导分化作用敏感。JMRD3细胞系是RWLeu4的VD3抗性变体，通过在VD3存在下连续传代RWLeu4而筛选获得。自发VD3抗性变体的分离表明，RWLeu4细胞群体中存在表型不同的细胞。因此，对RWLeu4细胞的单细胞克隆进行了分离和鉴定。研究了四个克隆细胞群体，它们分为三组，对VD3的抗增殖和诱导分化作用的反应不同。令人惊讶的是，克隆对VD3的反应程度与维生素D受体（VDR）的基础水平没有相关性。RWLeu4 - 3和RWLeu4 - 4是对VD3抗增殖作用最敏感的克隆（ED50约等于1 nM）；然而，RWLeu4 - 3表达的VDR基础水平与亲代细胞和RWLeu4 - 2克隆中的相似，而在RWLeu4 - 4中，VD3结合和VDR蛋白低于检测限。此外，RWLeu4 - 10表达的VDR蛋白基础水平最高，但对VD3的抗增殖作用相对抗性（ED50≥30 nM）。与JMRD3一样，根据生化过程和细胞表面抗原表达的诱导判断，RWLeu4 - 10仍然能够对VD3作出分化反应。尽管VD3处理会增加所有克隆中的VDR蛋白水平和DNA结合活性，但在RWLeu4 - 4中检测到了改变的DNA - 蛋白质复合物。我们的结果表明，对VD3抗增殖和诱导分化作用的敏感性不仅取决于VDR的表达水平，还可能需要VDR的翻译后修饰或与其他核转录因子的复杂相互作用。
