Key Laboratory of Carcinogenesis and Translational Research, (MOE/Beijing), Division of Etiology, Peking University Cancer Hospital and Institute, Beijing, 100142, China.
State Key Laboratory of Holistic Integrative Management of Gastrointestinal Cancers, Department of Pathology, Peking University Cancer Hospital and Institute, Beijing, 100142, China.
Gastric Cancer. 2024 Sep;27(5):986-997. doi: 10.1007/s10120-024-01515-4. Epub 2024 Jun 1.
The CDKN2A gene is frequently affected by somatic copy number variations (SCNVs, including deletions and amplifications [SCNdel and SCNamp]) in the cancer genome. Using surgical gastric margin tissue samples (SMs) as the diploid reference in SCNV analysis via CDKN2A/P16-specific real-time PCR (P16-Light), we previously reported that the CDKN2A SCNdel was associated with a high risk of metastasis of gastric carcinoma (GC). However, the status of CDKN2A SCNVs in SMs and their clinical significance have not been reported.
Peripheral white blood cell (WBC) and frozen GC and SM tissue samples were collected from patients (n = 80). Droplet digital PCR (ddPCR) was used to determine the copy number (CN) of the CDKN2A gene in tissue samples using paired WBCs as the diploid reference.
A novel P16-ddPCR system was initially established with a minimal proportion (or limit, 10%) of the detection of CDKN2A CN alterations. While CDKN2A SCNamp events were detected in both SMs and GCs, fewer CDKN2A SCNdel events were detected in SMs than in GCs (15.0% vs. 41.3%, P = 4.77E-04). Notably, significantly more SCNamp and fewer SCNdel of the CDKN2A gene were detected in SMs from GC patients without metastasis than in those from patients with lymph node metastasis by P16-ddPCR (P = 0.023). The status of CDKN2A SCNVs in SM samples was significantly associated with overall survival (P = 0.032). No cancer deaths were observed among the 11 patients with CDKN2A SCNamp.
CDKN2A SCNVs in SMs identified by P16-ddPCR are prevalent and significantly associated with GC metastasis and overall survival.
CDKN2A 基因在癌症基因组中经常受到体细胞拷贝数变异(SCNVs,包括缺失和扩增[SCNdel 和 SCNamp])的影响。我们之前使用手术胃边缘组织样本(SMs)作为 CDKN2A/P16 特异性实时 PCR(P16-Light)分析中的二倍体参考,报道了 CDKN2A SCNdel 与胃癌(GC)转移的高风险相关。然而,SMs 中 CDKN2A SCNVs 的状态及其临床意义尚未报道。
从患者(n=80)中收集外周血白细胞(WBC)和冷冻 GC 和 SM 组织样本。使用液滴数字 PCR(ddPCR),使用配对的 WBC 作为二倍体参考,确定组织样本中 CDKN2A 基因的拷贝数(CN)。
最初建立了一种新的 P16-ddPCR 系统,该系统可以检测到 CDKN2A CN 改变的最小比例(或极限,10%)。虽然在 SMs 和 GCs 中都检测到了 CDKN2A SCNamp 事件,但在 SMs 中检测到的 CDKN2A SCNdel 事件较少(15.0%对 41.3%,P=4.77E-04)。值得注意的是,通过 P16-ddPCR 检测,无淋巴结转移的 GC 患者的 SM 中 CDKN2A 基因的 SCNamp 显著更多,而 SCNdel 则更少(P=0.023)。SM 样本中 CDKN2A SCNVs 的状态与总生存期显著相关(P=0.032)。在 11 名 CDKN2A SCNamp 患者中,没有观察到癌症死亡。
通过 P16-ddPCR 鉴定的 SMs 中的 CDKN2A SCNVs 普遍存在,与 GC 转移和总生存期显著相关。