Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Samsung Genome Institute, Samsung Medical Center, Seoul, Korea.
Cancer Res Treat. 2022 Jan;54(1):40-53. doi: 10.4143/crt.2021.151. Epub 2021 May 25.
We investigated the feasibility of using an anatomically localized, target-enriched liquid biopsy (TLB) in mouse models of lung cancer.
After irradiating xenograft mouse with human lung cancer cell lines, H1299 (NRAS proto-oncogene, GTPase [NRAS] Q61K) and HCC827 (epidermal growth factor receptor [EGFR] E746-750del), circulating (cell-free) tumor DNA (ctDNA) levels were monitored with quantitative polymerase chain reaction on human long interspersed nuclear element-1 and cell line-specific mutations. We checked dose-dependency at 6, 12, or 18 Gy to each tumor-bearing mouse leg using 6-MV photon beams. We also analyzed ctDNA of lung cancer patients by LiquidSCAN, a targeted deep sequencing to validated the clinical performances of TLB method.
Irradiation could enhance the detection sensitivity of NRAS Q61K in the plasma sample of H1299-xenograft mouse to 4.5- fold. While cell-free DNA (cfDNA) level was not changed at 6 Gy, ctDNA level was increased upon irradiation. Using double-xenograft mouse with H1299 and HCC827, ctDNA polymerase chain reaction analysis with local irradiation in each region could specify mutation type matched to transplanted cell types, proposing an anatomically localized, TLB. Furthermore, when we performed targeted deep sequencing of cfDNA to monitor ctDNA level in 11 patients with lung cancer who underwent radiotherapy, the average ctDNA level was increased within a week after the start of radiotherapy.
TLB using irradiation could temporarily amplify ctDNA release in xenograft mouse and lung cancer patients, which enables us to develop theragnostic method for cancer patients with accurate ctDNA detection.
我们研究了在肺癌小鼠模型中使用解剖定位、靶向富集的液体活检（TLB）的可行性。
用人类肺癌细胞系 H1299（NRAS 原癌基因，GTP 酶 [NRAS] Q61K）和 HCC827（表皮生长因子受体 [EGFR] E746-750del）照射异种移植小鼠后，通过定量聚合酶链反应监测人长散布核元件-1 和细胞系特异性突变的循环（无细胞）肿瘤 DNA（ctDNA）水平。我们使用 6-MV 光子束检查了每个荷瘤小鼠腿部 6、12 或 18 Gy 的剂量依赖性。我们还通过 LiquidSCAN 分析了肺癌患者的 ctDNA，这是一种靶向深度测序，用于验证 TLB 方法的临床性能。
照射可将 H1299 异种移植小鼠血浆样本中 NRAS Q61K 的检测灵敏度提高到 4.5 倍。虽然 6 Gy 时细胞游离 DNA（cfDNA）水平没有变化，但照射后 ctDNA 水平增加。使用具有 H1299 和 HCC827 的双重异种移植小鼠，对每个区域进行局部照射的 ctDNA 聚合酶链反应分析可以确定与移植细胞类型匹配的突变类型，提出了一种解剖定位、TLB。此外，当我们对 11 名接受放疗的肺癌患者进行 cfDNA 靶向深度测序以监测 ctDNA 水平时，放疗开始后一周内平均 ctDNA 水平升高。
使用照射的 TLB 可以暂时放大异种移植小鼠和肺癌患者的 ctDNA 释放，使我们能够开发出具有准确 ctDNA 检测的癌症患者的治疗方法。
