淋巴瘤细胞系中范可尼贫血／BRCA途径缺陷的探讨

Search for Fanconi anemia/BRCA pathway defects in lymphoma cell lines

目的寻找维持基因稳定性的范可尼贫血（Fanconi anemia，FA）／BRCA途径发生缺陷与T和B细胞淋巴瘤潜在发病机制的关系。方法筛选19种来源于不同亚型的淋巴瘤细胞系，Western印迹分析相关FA蛋白的表达，细胞生长抑制实验检测丝裂霉素C（mitomycin C，MMC）敏感性，流式细胞仪检测MMC诱导的细胞周期阻滞，染色体断裂试验和DNA测序检测基因的突变。结果在两种淋巴瘤细胞系HT和Sudhl4中，存在FANCN蛋白表达缺失，这种缺失与MMC诱导的G期细胞阻滞、细胞生长抑制增强和较高的染色体断裂发生率结果一致。DNA测序发现HT细胞系中，FANCN基因外显子5a片段中存在点突变c．1769C〉T，P．A590V；Sudhl4细胞系中未发现FANCN的任何突变。结论FANCN基因c．1769C〉T突变可能是导致FANCN蛋白表达缺失或者是使该蛋白不稳定及功能丧失的原因。

Objective To investigate the possible relationship between defects in the FA/BRCA pathway of genomic stability and potential pathogenesis of T and B cell lymphoma. Methods Nineteen cell lines derived from diverse subtypes of lymphoma for possible FA pathway defects were screened. Results No defect in FANCD2 ubiquitination was observed. However, the FANCN protein was absent in cell lines HT and Sudh14. Tiffs absence was correlated with enhanced MMC-induced G2 arrest, growth inhibition and high chromosomal breakage rate in both cell lines. In addition, in exon-5a of FANCN gene, a mutation of c. 1769 C 〉 T, p. A590V was found in cell line HI＇, but not in cell line Sudhl4. Conclusion This mutation may be the reason causing the absence of the FANCN protein expression or making the protein unstable and losing its function.