Department of Clinical Biochemistry, School of Medicine, Mashhad University of Medical Sciences, Mashhad, IRAN; Student Research Committee, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Department of Microbiology and Virology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran; Antimicrobial resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Exp Mol Pathol. 2021 Dec;123:104687. doi: 10.1016/j.yexmp.2021.104687. Epub 2021 Sep 27.
The JC polyomavirus has been blamed to contribute in colorectal cancer (CRC), however, the topic is still controversial. Varying detection rate of JCPyV genome has been reported mainly due to technical reasons. Here, we provide summative data on the topic, with emphasize on technical issues.
Formalin-fixed paraffin-embedded tissue samples from 50 patients with CRC, consisting of tumoral and non-cancerous marginal tissue (totally 100 samples) were included in the study. After DNA extraction, specific JCPyV T-Ag sequences were targeted using Real-time PCR. To unwind the supercoiled JCPyV genome, pretreatment with topoisomerase I, was applied. Immunohistochemical (IHC) staining was performed using an anti-T-Ag monoclonal antibody.
In the first attempts, no samples were found to be positive in Real-time PCR assays. However, JCPyV sequences were found in 60% of CRC tissues and 38% of non-cancerous colorectal mucosa after application of pre-treatment step with topoisomerase I enzyme (P = 0.028). T-Ag protein was found in the nuclear compartment of the stained cells in IHC assays.
The presence of JCPyV in CRC tissues, as well as T-Ag localization in the nucleolus, where its oncogenic effect takes place, may provide supporting evidence for JCPyV involvement in CRC development. The study highlights the importance of using topoisomerase I to enhance JCPyV genome detection. Also, colorectal tissue is one of the permissive human tissue for JC resistance after preliminary infection.
JC 多瘤病毒被归咎于结直肠癌（CRC）的发生，但该主题仍存在争议。JCPyV 基因组的检测率因技术原因而有所不同。在这里，我们提供了该主题的总结性数据，重点关注技术问题。
本研究纳入了 50 例 CRC 患者的福尔马林固定石蜡包埋组织样本，包括肿瘤和非癌性边缘组织（共 100 个样本）。提取 DNA 后，使用实时 PCR 靶向特定的 JCPyV T-Ag 序列。为了解开 JCPyV 基因组的超螺旋结构，应用拓扑异构酶 I 进行预处理。使用抗 T-Ag 单克隆抗体进行免疫组织化学（IHC）染色。
在最初的尝试中，实时 PCR 检测未发现任何样本为阳性。然而，在应用拓扑异构酶 I 酶预处理步骤后，60%的 CRC 组织和 38%的非癌性结直肠黏膜中发现了 JCPyV 序列（P=0.028）。在 IHC 检测中，T-Ag 蛋白在染色细胞的核内区被发现。
JCPyV 在 CRC 组织中的存在，以及 T-Ag 在核仁中的定位，其致癌作用发生在核仁中，这可能为 JCPyV 参与 CRC 发生提供了支持性证据。该研究强调了使用拓扑异构酶 I 增强 JCPyV 基因组检测的重要性。此外，结直肠组织是原发性感染后对 JC 具有抗性的人类组织之一。
