目的：探讨RAS相关区域家族5A（Ras-association domain family 5A，RASSF5A）基因在淋巴瘤患者及正常人外周血中DNA甲基化和mRNA表达状态，并研究其与患者临床表现的关系。方法：应用甲基化特异性PCR（methylation-specific PCR，MSP）及RT-PCR方法检测河北医科大学第四附属医院2013年10月至2015年3月收治的弥漫性大B细胞淋巴瘤患者74例、T细胞淋巴瘤患者42例及健康志愿者42人的外周血中RASSF5A基因甲基化及mRNA表达状态。分析其与临床表现之间的关系。结果：RASSF5A在弥漫性大B细胞淋巴瘤和T细胞淋巴瘤中的甲基化率分别为64.9%（48/74）和 73.8%(31/42)，明显高于正常人的7.1%（3/42)（P<0.05）；而其mRNA表达量分别为0.54±0.17和0.52±0.18，均低于正常人的0.86±0.10（P<0.05)。弥漫性大B细胞淋巴瘤中RASSF5A基因启动子甲基化阳性的mRNA相对表达量（0.51±0.18）低于甲基化阴性的mRNA表达量（0.60±0.17）（P<0.05）。T细胞淋巴瘤中RASSF5A基因启动子甲基化阳性的mRNA相对表达量（0.50±0.15）低于甲基化阴性的mRNA表达量（0.63±0.12）（P<005）。RASSF5A基因在弥漫性大B细胞淋巴瘤中的甲基化率与患者的LDH、IPI评分及Ki67相关(P<0.05)；RASSF5A基因在T细胞淋巴瘤中的甲基化率与患者的临床分期、结外累及及Ki-67相关(P<0.05)。RASSF5A基因在弥漫性大B细胞淋巴瘤中mRNA的表达量与患者的IPI评分及结外累及相关(P<0.05)；RASSF5A基因在T细胞淋巴瘤中mRNA的表达量与患者的临床分期和结外累及相关(P<0.05)。结论：RASSF5A基因启动子甲基化可能是弥漫性大B细胞淋巴瘤和T细胞淋巴瘤发生的机制之一，mRNA表达沉默可能是表观遗传学机制之一。RASSF5A基因在弥漫性大B细胞淋巴瘤和T细胞淋巴瘤中主要可能起抑癌基因的作用，与淋巴瘤的侵袭性、恶性进程及预后有关。

Objective:To investigate the promoter methylation status of Ras-association domain family 5A (RASSF5A) gene and its mRNA expression level in in the peripheral blood of patients with lymphoma and normal people as well as its correlation to clinical manifestations. Methods：Methylation-specific PCR (MSP) and Reverse Transcriptase-PCR(RT-PCR) method were used to examine the methylation status and the mRNA expression of RASSF5A gene in peripheral blood of patients with diffused large B cell lymphoma or T cell lymphoma and healthy participants. The relationship between RASSF5Agene methylation and clinical data was further analyzed. Results: The methylation frequencies of RASSF5A in diffused large B cell lymphoma and T cell lymphoma (64.9% \[48/74\] and 73.8% \[31/42\]) were significantly higher than that of healthy participants (7.1% \[3/42\], all  P<0.05). The mRNA expressions of RASSF5A gene in diffused large B cell lymphoma and peripheral T cell lymphoma were (0.54±0.17) and (0.52±0.18), respectively, which were significantly lower than that of healthy participants (0.86±0.10) (P<0.05). The mRNA expression of RASSF5A gene with positive promoter methylation (\[0.51±0.18\]; \[0.50±0.15\]) was significantly lower than that of the gene with negative methylation (\[0.60±0.17\]; \[0.63±0.12\]) (all P<0.05) in both diffused large B cell lymphoma and T cell lymphoma. Methylation frequency of RASSF5A gene was associated with LDH, IPI, and Ki-67 (P<0.05) in diffused large B cell lymphoma, and associated with clinical stage, extranodal involvement and Ki-67 (P<0.05) in T cell lymphoma. The mRNA expression of RASSF5A gene was correlated with IPI score, extranodal involvement (P<0.05) in diffused large B cell lymphoma, and correlated with clinical stage and extranodal involvement (P<0.05) in T cell lymphoma. Conclusion: The methylation of RASSF5A gene may be associated with the occurrence of diffused large B cell lymphoma and T cell lymphoma, and mRNA expression silencing might be one of the mechanisms of epigenetics. RASSF5A gene may act as a tumor suppressor gene in diffused large B cell lymphoma and T cell lymphoma, which may be associated with tumor invasiveness, tumor malignant process and tumor prognosis.

国家自然科学基金资助项目（No. 81472335）