急性髓系白血病核仁磷酸蛋白基因及其突变检测方法的建立

本研究建立PCR技术检测白血病细胞核仁磷酸蛋白（nucleophosmin，NPM）基因及突变的方法。以白血病细胞系和白血病临床标本为研究对象，首先采用RT—PCR检测NPM mRNA表达水平，其次应用PCR方法检测NPM第12外显子，并对扩增产物进行测序分析，最后以插入NPMA型突变cDNA的质粒作为阳性模板，建立PCR检测NPM突变的方法并进行方法学评价，并采用此方法直接检测白血病细胞中是否存在NPM基因突变。结果表明：白血病细胞系NPM mRNA表达水平较正常单个核细胞对照组高，23例急性髓系白血病标本均不同程度地高表达NPM mRNA；采用PCR扩增联合测序分析发现，髓系白血病细胞系（THP1和K562）NPM基因组第12外显子无突变，但K562细胞NPM基因3’非编码区存在1个T碱基缺失；建立直接针对NPMA型突变cDNA的PCR方法，能特异扩增NPMA型突变基因；该方法重复性好，批内、批间变异系数分别为1．6％和3．1％，灵敏度为100PgcDNA；采用此方法从23例白血病临床标本中检出2例NPM突变阳性。结论：建立了检测NPM mRNA水平和A型突变的实验方法，发现白血病细胞高表达NPM mRNA水平，部分白血病患者NPM基因发生A型突变。

Establishment of the Methods to Detect Nucleophosmin Gene and Its Mutation in Acute Myelogenous Leukemia

This study was aimed to establish the PCR methods to detect nucleophosmin (NPM) gene and its mutation. 2 leukemia cell lines and 23 specimens from patients with acute myelogenous leukemia (AML) were investigated. The level of NPM mRNA was detected by RT-PCR. The exon-12 of NPM gene in leukemia cell lines was amplified by PCR and sequenced. Using the plasmid containing cDNA of NPM mutation A as a positive template, the PCR procedure to detect mutation A was established and evaluated. Then, the mutation of NPM was analyzed in 23 AML specimens. The results indicated that the expression level of NPM in leukemia cell lines was higher than that in normal cells. Different overexpression levels of NPM mRNA were found in all 23 AML specimens. PCR indicated that mutation had been not occurred at NPM exon-12 in THP1 and K562 cells, but a T base was deleted at 3' untranslated region of NPM gene in K562 cells. The PCR used for directly detecting NPM mutation A can specially amplify the NPM mutation gene. The method was reproducible, whose coefficient of variability was 1.6% and 3.1% in intra-and inter-assays respectively. The lowest detectable limit was 100 pg cDNA. Using the PCR methods, NPM mutation A could be detected in 2 out of 23 AML specimens, but NPM mutation A was not found in THP1 and K562 cells. It is concluded that the RT-PCT method detecting NPM mRNA level and the PCR method detecting directly NPM mutation are established. NPM mRNA is overexpressed in leukemia cells; NPM mutation A occurs in some AML patients.