Role of the tumor suppressor gene WT1 in human leukemogenesis.

为了阐明WT1基因在白血病细胞中的表达是异常的，还是仅仅反映了正常白血病细胞中WT1基因的表达，我们对正常造血祖细胞的WT1基因的表达水平进行了定量。以CD34^+CD33、CD38、CD34^+CD38、CD34^+CD38^-、CD34^+HLA-DR^+、CD34^+c-kit^&lt、Hight&GT、CD34^+c-kit-^&lt、CD34^+c-kit-^、CD34^+c-kit^-、CD34^+c-kit^-、CD34^+c-kit^-9个亚群。并将急性髓系白血病细胞分为四组(CD34^+CD33^-、CD34^+CD33^+、CD34^-CD33^+和CD34^-CD33^-)。用定量逆转录聚合酶链式反应检测FACS分选的正常造血祖细胞和白血病细胞以及FACS分选的白血病细胞WT1的表达。CD34~+和CD34~+细胞群以及BM和CB的9个CD34~+亚群中WT1的表达水平很低(1.0~2.4×10~(-2))或检测不到(K562细胞的WT1表达水平定义为1.0)，而FACS分选和未分选的白血病细胞WT1的平均表达水平为2.4~9.3×10~(-2)~(-1)。因此，正常造血祖细胞中WT1的表达水平至少比白血病细胞低10倍。因此，我们找不到任何正常的BM或CB以与白血病细胞相当的水平表达WT1。这些结果表明WT1基因在白血病细胞中异常过表达，并暗示该基因参与了人类白血病的发生。

To clarify whether the expression of the WT1 gene in leukemic cells is aberrant or merely reflects that in normal counterparts, the expression levels of the WT1 gene were quantitated for normal hematopoietic progenitor cells. Bone marrow (BM) and umbilical cord blood (CB) cells were fluorescence-activated cell sorting (FACS)-sorted into CD34^+ and CD34^- cell populations, and the CD34^+ cells into nine subsets (CD34^+CD33^-, CD34^+CD33^+.CD34^+CD38^-, CD34^+CD38^+, CD34^+HLA-DR^-, CD34^+HLA-DR^+, CD34^+c-kit^<hight>, CD34^+c-kit-^<low>, and CD34^+c-kit^-) according to the expression levels of CD34, CD33, CD38, HLA-DR,and c-kit. Moreover, acute myeloid leukemic cells were also FACS-sorted into four populations (CD34^+CD33^-, CD34^+CD33^+, CD34^-CD33^+, and CD34^-CD33^-). FACS-sorted normal hematopoietic progenitor and leukemic cells and FACS-unsorted leukemic cells were examined for the WT1 expression by quantitative reverse transcriptase-polymerase chain reaction. The WT1 expression in the CD34^+ and CD34^- cell populations and in the nine CD34^+ subsets of BM and CB was at either very low (1.0 to 2.4 x 10^<-2>) or undetectable (<10^<-2>) levels (the WT1 expression level of K562 cells was defined as 1.0), whereas the average levels of WT1 expression in FACS-sorted and-unsorted leukemic cells were 2.4 to 9.3 x 10^<-1>. Thus, the WT1 expression levels in normal hematopoietic progenitor cells were at least 10 times less than those in leukemic cells. Therefore, we could not find any normal counterparts of BM or CB that expressed the WT1 at levels comparable with those in leukemic cells. These results indicate an aberrant overexpression of the WT1 gene in leukemic cells and imply the involvement of this gene in human leukemogenesis.