朗格汉斯细胞组织细胞增生症中TP53蛋白表达及基因突变检测

Detection TP53 Protein Expression and Gene Mutation in Langerhans’Cell Histiocytosis

目的检测朗格汉斯细胞组织细胞增生症(LCH)中TP53蛋白表达和TP53基因全外显子突变,以探讨TP53在LCH发生发展中的作用机制。方法应用免疫组化SP法检测38例LCH中TP53蛋白水平;对16例TP53蛋白阳性组织原位提取DNA后PCR直接测序检测TP53基因外显子2～11的变化。结果 38例LCH样本TP53蛋白阳性16例(42.11%)。在16例阳性的平均吸光度比较中,分别为10例广泛型(MS)(0.1206±0.0088),6例局限型(SS)(0.1221±0.0030),二者表达差异无统计学意义(P>0.05)。PCR直接测序16例阳性LCH,2～11号外显子突变未见异常。TP53codon72基因型频率为:LCH组PRO型3例,ARG型5例,PRO/ARG型8例;与40例正常对照相比较分布差异无统计学意义(P>0.05)。LCH组中MS组PRO型2例,ARG型3例,PRO/ARG型5例;SS组PRO型1例,ARG型2例,PRO/ARG型3例。两组频率分布差异无统计学意义(P>0.05)。结论 LCH中有朗格汉斯细胞组织细胞TP53蛋白异常表达,但在临床分型上比较差异无统计学意义;LCH中TP53基因在全外显子无突变。TP53codon72基因型与正常人群一致且与临床分型及预后无相关。在LCH中可能有另一无关基因突变的机制影响了TP53蛋白表达。

Objective To determine whether TP53 gene plays a role in the pathogenesis of Langerhans＇ Cell Histiocy- tosis （LCH） ,we studied the expression of TP53 protein and mutation of TP53 gene in LCH biopsies. Meth- ods The expression of TP53 protein was detected by immunohistochemical SP method in 38 cases of Lange- rhans cell histiocytosis. The mutation in TP53 gene exon 2 to 11 was identified by polymerase chain reaction and subsequently conformed by DNA sequencing in the 16 TP53 protein positive biopsies. Results TP53 protein expression was detected in 16/38 （42.11% ） LCH biopsies. In those biopsies, there were no signifi- cant difference between the average optical density of multisystem （MS ,0. 120 6 ± 0. 008 8 ） and single-sys- tem （SS ,0. 122 1 ± 0. 003 0） respectively（ P 〉 0.05 ）. No mutations in the TP53 gene exon 2 to 11 were de- tected in those positive biopsies. For genetic genotype of the polymorphism of TP53 gene codon 72, there were PRO in 3 cases,ARG in 5 cases, PRO/ARG in 8 cases in LCH group （TP53 protein positive）. Com- pared with 40 normal controls, Chi-square analysis showed there was no significant difference for distribution of the three genotypes （ P 〉 0.05 ）. Then, for the clinical classification, the cases of PRO, ARG and PRO/ ARG were 2,3,5 in MS and 1,2,3 in SS,respectively. Chi-square analysis also showed no significant differ- ences （P 〉 0.05 ）. Conclusion The TP53 protein is abnormally expressed in LCH, although there was no significant difference with the clinical classification. There is no TP53 gene mutation in LCH. The TP53 co- don 72 genotype distribution was consistent with the normal population and not related with clinical classifica- tion. We speculate that the abnormality of TP53 gene expression in LCH may not result from gene mutation but an unknown mechanism.