Background Lynch syndrome (LS) is a hereditary cancer predisposition syndrome caused by germline mutations in DNA mismatch repair (MMR) genes, which lead to high microsatellite instability (MSI-H) and frameshift mutations (FSMs) at coding mononucleotide repeats (cMNRs) in the genome. Recurrent FSMs in these regions are thought to play a central role in the increased risk of various cancers. However, there are no biomarkers currently available for the surveillance of MSI-H-associated cancers. Methods An FSM-based biomarker panel was developed and validated by targeted next generation sequencing of supernatant DNA from cultured MSI-H colorectal cancer cells. This supported selection of 122-FSM targets as potential biomarkers. This biomarker panel was then tested using matched tumor, adjacent normal tissue, and buffy coat (53 samples), and blood-derived cell-free DNA (cfDNA; 38 samples) obtained from 45 cases of MSI-H/MMR deficient (MMRd) patients/carriers. cfDNA from 84 healthy individuals was also sequenced to assess background noise. Results Recurrent FSMs at cMNRs were detectable not only in tumors, but also in cfDNA from MSI-H/MMRd cases including a LS carrier with a varying range of target detection (up to 85.2%), whereas they were virtually undetectable in healthy individuals. ROC analysis showed high sensitivity and specificity (AUC = 0.94) of the investigated panel. Conclusions We demonstrated that FSMs can be detected in cfDNA from MSI-H/MMRd cases and asymptomatic carriers. The 122-target FSM panel described here has promise as a tool for improved surveillance of MSI-H/MMRd carriers with the potential to reduce the frequency of invasive screening methods for this high-cancer-risk cohort.

中文翻译：

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外周血中的移码突变作为监测林奇综合征的生物标志物

背景林奇综合征（LS）是一种遗传性癌症易感综合征，由 DNA 错配修复（MMR）基因种系突变引起，导致编码单核苷酸重复序列（cMNR）高度微卫星不稳定性（MSI-H）和移码突变（FSM）。基因组。这些区域的复发性 FSM 被认为在各种癌症风险增加中发挥着核心作用。然而，目前没有可用于监测 MSI-H 相关癌症的生物标志物。方法 通过对培养的 MSI-H 结直肠癌细胞上清 DNA 进行靶向下一代测序，开发并验证了基于 FSM 的生物标记物组。这支持选择 122-FSM 靶标作为潜在的生物标志物。然后使用匹配的肿瘤、邻近正常组织和血沉棕黄层（53 个样本）以及从 45 例 MSI-H/MMR 缺陷 (MMRd) 病例中获得的血源性游离 DNA（cfDNA；38 个样本）对该生物标志物组进行测试患者/携带者。还对 84 名健康个体的 cfDNA 进行了测序，以评估背景噪音。结果 cMNR 处的复发 FSM 不仅在肿瘤中可检测到，而且在 MSI-H/MMRd 病例的 cfDNA 中也可检测到，其中包括具有不同目标检测范围的 LS 携带者（高达 85.2%），而在健康个体中几乎无法检测到。ROC 分析显示所研究的组具有高灵敏度和特异性 (AUC = 0.94)。结论 我们证明，可以在 MSI-H/MMRd 病例和无症状携带者的 cfDNA 中检测到 FSM。这里描述的 122 个目标 FSM 面板有望成为改进 MSI-H/MMRd 携带者监测的工具，并有可能减少针对这一高癌症风险群体的侵入性筛查方法的频率。