Siciliano M C, Tornambè S, Cevenini G, Sorrentino E, Granai M, Giovannoni G, Marrelli D, Biviano I, Roviello F, Yoshiyama H, Leoncini L, Lazzi S, Mundo L
Section of Pathology, Department of Medical Biotechnology, University of Siena, Siena, Italy.
Department of Medical Biotechnology, University of Siena, Siena, Italy.
Infect Agent Cancer. 2022 Nov 17;17(1):57. doi: 10.1186/s13027-022-00469-5.
The Epstein-Barr virus (EBV) causes various B-cell lymphomas and epithelial malignancies, including gastric cancer (GC) at frequencies ranging from 5 to 10% in adenocarcinomas (ADK) to 80% in GC with lymphoid stroma (GCLS). Using high-sensitivity methods, we recently detected EBV traces in a large cohort of EBV-negative B-cell lymphomas, suggesting a hit-and-run mechanism.
Here, we used routine and higher-sensitivity methods [droplet digital PCR (ddPCR) for EBV segments on microdissected tumour cells and RNAscope for EBNA1 mRNA] to assess EBV infection in a cohort of 40 GCs (28 ADK and 12 GCLS).
ddPCR documented the presence of EBV nucleic acids in rare tumour cells of several cases conventionally classified as EBV-negative (ADK, 8/26; GCLS, 6/7). Similarly, RNAscope confirmed EBNA1 expression in rare tumour cells (ADK, 4/26; GCLS, 3/7). Finally, since EBV induces epigenetic changes that are heritable and retained after complete loss of the virus from the host cell, we studied the methylation pattern of EBV-specifically methylated genes (Timp2, Eya1) as a mark of previous EBV infection. Cases with EBV traces showed a considerable level of methylation in Timp2 and Eya1 genes that was similar to that observed in EBER-ISH positive cases and greater than cases not featuring any EBV traces.
These findings suggest that: (a) EBV may contribute to gastric pathogenesis more widely than currently acknowledged and (b) indicate the methylation changes as a mechanistic framework for how EBV can act in a hit-and-run manner. Finally, we found that the viral state was of prognostic significance in univariate and multivariate analyses.
爱泼斯坦-巴尔病毒（EBV）可引发多种B细胞淋巴瘤和上皮性恶性肿瘤，包括胃癌（GC），在腺癌（ADK）中的感染频率为5%至10%，在伴有淋巴样间质的胃癌（GCLS）中高达80%。我们最近采用高灵敏度方法在一大批EBV阴性B细胞淋巴瘤中检测到EBV痕迹，提示存在“打了就跑”机制。
在此，我们使用常规及更高灵敏度方法[对显微切割的肿瘤细胞进行EBV片段的液滴数字PCR（ddPCR）以及对EBNA1 mRNA进行RNAscope检测]来评估40例GC（28例ADK和12例GCLS）中的EBV感染情况。
ddPCR证实，在一些传统上分类为EBV阴性的病例的罕见肿瘤细胞中存在EBV核酸（ADK，8/26；GCLS，6/7）。同样，RNAscope证实了在罕见肿瘤细胞中存在EBNA1表达（ADK，4/26；GCLS，3/7）。最后，由于EBV可诱导表观遗传变化，这种变化具有遗传性且在病毒从宿主细胞完全消失后仍会保留，我们研究了EBV特异性甲基化基因（Timp2、Eya1）的甲基化模式，将其作为既往EBV感染的标志。有EBV痕迹的病例在Timp2和Eya1基因中显示出相当程度的甲基化，这与EBER原位杂交阳性病例中观察到的情况相似，且高于未出现任何EBV痕迹的病例。
这些发现表明：（a）EBV对胃癌发病机制的作用可能比目前所认识的更为广泛；（b）表明甲基化变化是EBV如何以“打了就跑”方式发挥作用的机制框架。最后，我们发现病毒状态在单变量和多变量分析中具有预后意义。
