Scarpa Marco, Scarpa Melania, Castagliuolo Ignazio, Erroi Francesca, Basato Silvia, Brun Paola, Angriman Imerio, Castoro Carlo
Esophageal and Digestive Tract Surgery Unit, Veneto Institute of Oncology IOV - IRCCS, Padova, Italy.
Department of Molecular Medicine, University of Padova, Padova, Italy.
BMC Cancer. 2016 Jul 4;16:388. doi: 10.1186/s12885-016-2405-z.
The lack of positive costimulatory molecules represents one of the mechanisms by which tumor cells evade immune surveillance. Promoter hypermethylation plays a major role in cancer development through transcriptional silencing of critical genes. The aim of this study was to examine the expression of the costimulatory molecule CD80 in relationship with genomic methylation in non-inflammatory colon carcinogenesis.
Colonic mucosal samples were collected from healthy subjects (n = 30) and from dysplastic adenoma (n = 14), and colon adenocarcinoma (n = 10). DNA methyltransferases-1, -3a, -3b and CD80 mRNA expression were quantified by real time qRT-PCR. The methylation status of CDH13, APC, MLH1, MGMT1 and RUNX3 gene promoters was assessed by methylation-specific PCR. CD80 expression was assessed in HT29, HCT-15 and LoVo cell lines after treatment with the DNA-methyltransferase inhibitor 5-Aza-2'-deoxycytidine.
CD80 mRNA levels were significantly lower in the non-inflammatory dysplastic colonic mucosa of patients with one or more methylated genes and inversely correlated with patients' methylation scores (τ = -0.41, p = 0.05 and τ = -0.37, p = 0.05, respectively). Treatment with 5-Aza-2'-deoxycytidine significantly increased CD80 expression both in terms of the level of CD80 mRNA (p = 0.007) and of CD80+ cells (p = 0.003).
These results indicate that the failure of immune surveillance mechanisms in non-inflammatory colon carcinogenesis may be linked to genomic methylation directly or indirectly affecting CD80 expression.
缺乏阳性共刺激分子是肿瘤细胞逃避免疫监视的机制之一。启动子高甲基化通过关键基因的转录沉默在癌症发展中起主要作用。本研究的目的是探讨共刺激分子CD80的表达与非炎症性结肠癌发生过程中基因组甲基化的关系。
收集健康受试者（n = 30）、发育异常腺瘤（n = 14）和结肠腺癌（n = 10）的结肠黏膜样本。通过实时定量逆转录聚合酶链反应（qRT-PCR）对DNA甲基转移酶-1、-3a、-3b和CD80 mRNA表达进行定量。通过甲基化特异性PCR评估CDH13、APC、MLH1、MGMT1和RUNX3基因启动子的甲基化状态。在用DNA甲基转移酶抑制剂5-氮杂-2'-脱氧胞苷处理后，评估HT29、HCT-15和LoVo细胞系中的CD80表达。
在具有一个或多个甲基化基因的患者的非炎症性发育异常结肠黏膜中，CD80 mRNA水平显著降低，且与患者的甲基化评分呈负相关（τ = -0.41，p = 0.05；τ = -0.37，p = 0.05）。用5-氮杂-2'-脱氧胞苷处理后，无论是CD80 mRNA水平（p = 0.007）还是CD80+细胞水平（p = 0.003），CD80表达均显著增加。
这些结果表明，非炎症性结肠癌发生过程中免疫监视机制的失效可能与直接或间接影响CD80表达的基因组甲基化有关。
