Narendran Aru, Ganjavi Hooman, Morson Natalie, Connor Alison, Barlow Jason W, Keystone Edward, Malkin David, Freedman Melvin H
Southern Alberta Children's Cancer Program, Alberta Children's Hospital, Calgary, Alberta, Canada.
Exp Hematol. 2003 Aug;31(8):693-701. doi: 10.1016/s0301-472x(03)00159-0.
Genetic alterations, including p53 mutations, have been identified in the stroma of solid tumors and are thought be involved in the induction of tumor growth and metastasis. We tested the hypothesis that somatic molecular alterations in bone marrow stromal cells provide a favorable growth environment for leukemic cells.
We established an in vitro model consisting of stroma expressing mutant p53 (Cys135Ser) to study its ability to support growth of cells from a pre-B acute lymphoblastic leukemia (ALL) cell line. Normal and leukemic bone marrow stromal cells were screened for p53 mutations by mutant-specific ELISA, SSCP, and direct sequencing. Secretion of vascular endothelial growth factor (VEGF) was measured by quantitative ELISA.
Transfection of stromal cells with mutant p53 increased synthesis of VEGF and supported the growth of leukemic cells. An ELISA-based assay suggested the occurrence of in vivo p53 alterations in bone marrow stromal cells from 2 of 12 ALL patients screened. Direct sequencing of one of these samples revealed a somatic heterozygous p53 gene mutation (Asp49His). This sample secreted more VEGF and provided increased growth support to leukemic cells. The ability of Asp 49His-p53 to increase the expression of VEGF was confirmed with transfection experiments in a p53-null cell line.
Our findings indicate that genetic alterations, such as p53 mutations, in stromal cells can increase stromal-derived support of leukemia growth. Increased synthesis of pro-angiogenic cytokines, such as VEGF, may constitute one possible pathway by which this process is mediated.
在实体瘤基质中已鉴定出包括p53突变在内的基因改变，并且认为其与肿瘤生长和转移的诱导有关。我们检验了以下假设：骨髓基质细胞中的体细胞分子改变为白血病细胞提供了有利的生长环境。
我们建立了一个由表达突变型p53（Cys135Ser）的基质组成的体外模型，以研究其支持前B急性淋巴细胞白血病（ALL）细胞系细胞生长的能力。通过突变特异性ELISA、SSCP和直接测序对正常和白血病骨髓基质细胞进行p53突变筛查。通过定量ELISA测量血管内皮生长因子（VEGF）的分泌。
用突变型p53转染基质细胞可增加VEGF的合成并支持白血病细胞的生长。基于ELISA的检测表明，在筛查的12例ALL患者中的2例患者的骨髓基质细胞中发生了体内p53改变。对其中一个样本进行直接测序，发现了一个体细胞杂合p53基因突变（Asp49His）。该样本分泌更多的VEGF，并为白血病细胞提供了更强的生长支持。在p53基因缺失的细胞系中进行转染实验，证实了Asp 49His-p53增加VEGF表达的能力。
我们的研究结果表明，基质细胞中的基因改变，如p53突变，可增加基质对白血病生长的支持。促血管生成细胞因子如VEGF合成的增加可能是介导这一过程的一种可能途径。
