Disciplina de Genética, Departamento de Morfologia e Genética, Universidade Federal de São Paulo, Rua Botucatu, 740, São Paulo, São Paulo, 04023900, Brazil.
Disciplina de Gastroenterologia, Departamento de Medicina, Universidade Federal de São Paulo, Rua Loefgreen, 1726, São Paulo, São Paulo, 04040002, Brazil.
J Mol Med (Berl). 2020 May;98(5):707-717. doi: 10.1007/s00109-020-01902-1. Epub 2020 Apr 13.
Gastric cancer (GC) is the third leading cause of cancer-related death worldwide. Very few therapeutic options are currently available in this neoplasia. The use of 5-Aza-2'-deoxycytidine (5-AZAdC) was approved for the treatment of myelodysplastic syndromes, and this drug can treat solid tumours at low doses. Epigenetic manipulation of GC cell lines is a useful tool to better understand gene expression regulatory mechanisms for clinical applications. Therefore, we compared the gene expression profile of 5-AZAdC-treated and untreated GC cell lines by a microarray assay. Among the genes identified in this analysis, we selected NRN1 and TNFAIP3 to be evaluated for gene expression by RT-qPCR and DNA methylation by bisulfite DNA next-generation sequencing in 43 and 52 pairs of GC and adjacent non-neoplastic tissue samples, respectively. We identified 83 candidate genes modulated by DNA methylation in GC cell lines. Increased expression of NRN1 and TNFAIP3 was associated with advanced tumours (P < 0.05). We showed that increased NRN1 and TNFAIP3 expression seems to be regulated by DNA demethylation in GC samples: inverse correlations between the mRNA and DNA methylation levels in the promoter of NRN1 (P < 0.05) and the intron of TNFAIP3 (P < 0.05) were detected. Reduced NRN1 promoter methylation was associated with III/IV TNM stage tumours (P = 0.03) and the presence of Helicobacter pylori infection (P = 0.02). The identification of demethylated activated genes in GC may be useful in clinical practice, stratifying patients who are less likely to benefit from 5-AZAdC-based therapies. KEY MESSAGES: Higher expression of NRN1 and TNFAIP3 is associated with advanced gastric cancer (GC). NRN1 promoter hypomethylation contributes to gene upregulation in advanced GC. TNFAIP3 intronic-specific CpG site demethylation contributes to gene upregulation in GC. These findings may be useful to stratify GC patients who are less likely to benefit from DNA demethylating-based therapies.
胃癌（GC）是全球癌症相关死亡的第三大主要原因。目前，这种肿瘤的治疗选择非常有限。5-Aza-2'-脱氧胞苷（5-AZAdC）的使用已获得批准，用于治疗骨髓增生异常综合征，并且该药物可以在低剂量下治疗实体瘤。GC 细胞系的表观遗传操作是更好地了解基因表达调控机制的有用工具，可用于临床应用。因此，我们通过微阵列分析比较了 5-AZAdC 处理和未处理的 GC 细胞系的基因表达谱。在该分析中鉴定的基因中，我们选择 NRN1 和 TNFAIP3 通过 RT-qPCR 和 bisulfite DNA 下一代测序来评估基因表达，分别在 43 对 GC 和相邻非肿瘤组织样本和 52 对 GC 和相邻非肿瘤组织样本中进行。我们在 GC 细胞系中鉴定出 83 个受 DNA 甲基化调节的候选基因。NRN1 和 TNFAIP3 的表达增加与晚期肿瘤相关（P<0.05）。我们表明，GC 样本中 NRN1 和 TNFAIP3 表达的增加似乎受到 DNA 去甲基化的调节：在 NRN1 启动子（P<0.05）和 TNFAIP3 内含子（P<0.05）中检测到 mRNA 和 DNA 甲基化水平之间的反比相关性。NRN1 启动子甲基化降低与 III/IV TNM 期肿瘤（P=0.03）和幽门螺杆菌感染（P=0.02）相关。GC 中去甲基化激活基因的鉴定可能对临床实践有用，有助于分层那些不太可能从 5-AZAdC 为基础的治疗中获益的患者。关键信息：NRN1 和 TNFAIP3 的高表达与晚期胃癌（GC）相关。NRN1 启动子低甲基化有助于晚期 GC 中基因的上调。TNFAIP3 内含子特异性 CpG 位点去甲基化有助于 GC 中基因的上调。这些发现可能有助于分层那些不太可能从基于 DNA 去甲基化的治疗中获益的 GC 患者。
