鼻咽癌病人血浆和外周血白细胞EB病毒DNA定量分析

目的比较鼻咽癌(NPC)病人治疗前后血浆、外周血白细胞Epstein-Barr病毒(EBV)DNA水平的变化及癌组织EBV整合状况,探讨这些变化与NPC临床病理变化的关系.方法对150例初诊NPC病人治疗前后血浆和外周血白细胞、75名正常人血浆和外周血白细胞、49例NPC组织及47例鼻咽慢性炎组织EBV-DNA进行荧光定量聚合酶链反应(RQ-PCR)分析.结果 NPC病人治疗前血浆EBV-DNA水平及检出率分别为82 500拷贝/ml(中位数)和92%,均显著高于治疗后(0拷贝/ml,19%)和正常人(0拷贝/ml,12%)(P<0.05),而NPC病人治疗后和正常人血浆EBV-DNA水平和检出率差异均无显著意义(P>0.05).NPC病人治疗前外周血白细胞EBV-DNA水平及检出率(0拷贝/肌动蛋白,24%)与治疗后(0拷贝/肌动蛋白,14%)和正常人(0拷贝/肌动蛋白,16%)三者间差异均无显著意义(P>0.05).NPC病人治疗前、后及正常人血浆EBV-DNA水平与对应外周血白细胞EBV-DNA水平均无显著相关性(P>0.05).EBV-DNA(荧光定量PCR法)和EBER1(原位杂交法)在NPC组织检出率均为100%,显著高于鼻咽慢性炎组织中EBV-DNA和EBER1检出率(分别为40%和0)(P<0.05).NPC组织EBV-DNA水平为27.8拷贝/肌动蛋白(中位值),显著高于鼻咽慢性炎组织(0拷贝/肌动蛋白)(P<0.0001),NPC组织EBV-DNA水平与对应癌组织内EBER1阳性细胞占组织总细胞比率(中位值0.35)有显著正相关性(相关系数r= 0.513)(P<0.0001).NPC病人治疗前血浆EBV-DNA水平随临床TNM分期越晚而显著增高(Ⅰ、Ⅱ、Ⅲ、Ⅳ期中位值分别为2500、32 590、86 000和166 200拷贝/ml)(P=0.004).而NPC治疗前外周血白细胞EBV-DNA水平在TNM各期均为0拷贝/肌动蛋白,差异无显著意义(P>0.05).结论研究结果提示NPC病人血浆EBV-DNA水平是反映NPC肿瘤消长情况的灵敏、可靠的指标,可在分子水平对NPC的TNM分期进行补充.NPC病人血浆EBV-DNA水平与外周血白细胞EBV-DNA水平没有相关性,提示血浆EBV-DNA可能来源于肿瘤细胞的裂解释放,并反映病人体内瘤荷大小.

Quantitative analysis of Epstein-Barr virus DNA in plasma and peripheral blood cells in patients with nasopharyngeal carcinoma

OBJECTIVE: To quantitative analysis of Epstein-Barr virus (EBV) DNA levels in plasma, peripheral blood cells (PBCs) and tumor tissue in nasopharyngeal carcinoma (NPC), to investigate the relationship between EBV-DNA levels and clinical parameters. METHODS: Blood of 150 primary NPC and 49 corresponding tumor tissues, 47 nasopharyngitis tissues and blood of 75 controls were entered this investigation. Plasma and PBCs were isolated for quantitative detection of EBV-DNA by using real-time quantitative PCR (RQ-PCR). The paraffin-embedded tissue sections were conducted to quantitative detection of EBV-DNA, and EBER1 in situ hybridization (ISH) for calculating the percentage of positive cells on the tissue section. RESULTS: Plasma EBV-DNA levels and detecting rate in NPC before treatment (median 82 500 copies/ml, 92%) were significantly higher than that in NPC after treatment (median 0 copy/ml, 19%) and in controls (median 0 copy/ml, 12%) (P < 0.05), whereas there was no significant difference between NPC after treatment and controls (P > 0.05). There was no significant difference of PBCs EBV-DNA load and detecting rate in NPC before (0 copy/actin, 24%) and after treatment (0 copy/actin, 14%), as well as in controls (0 copy/actin, 16%) (P > 0.05). Plasma EBV-DNA level was not correlated to PBCs EBV-DNA load in NPC before (P = 0.92) and after treatment (P = 0.27), and controls (P = 0.74). EBV-DNA level (27.8 copies/actin) in NPC tumor tissues was significantly higher than that in nasopharyngitis (0 copy/actin) (P < 0.05), and was positively correlated to the ratio of EBER1 positive cells to total cells on the NPC section. In NPC patients, plasma EBV-DNA level was significantly increased in TNM stage I (2500 copies/ml), II (32 590 copies/ml), III (86 000 copies/ml) and IV (166 200 copies/ml), whereas there was no significantly difference of PBCs EBV-DNA loads in difference stages of NPC. CONCLUSION: Plasma EBV-DNA level is a more sensitive and reliable biomarker than PBCs EBV-DNA loads for reflection the tumor volumes in NPC patients. Plasma EBV-DNA detection will improve TNM staging in NPC clinical practice on molecular level.