Non-invasive sampling of DNA markers for pancreatic cancer screening

描述（由申请人提供）：胰腺癌通常是一种致命的疾病，5年生存率仅为1-4%。早期发现可以大大降低死亡率。KRAS癌基因突变（主要在密码子12）存在于<90%-95%的胰腺癌病例中。KRAS突变不是胰腺癌特有的，但在高危人群中早期发现这些突变，并结合诊断随访，可以挽救生命。粪便是一种非常有吸引力的癌症DNA来源，可用于早期筛查。然而，由胆汁盐、DNA酶和蛋白酶组成的胃肠道的恶劣环境降低了胰腺癌细胞和癌症DNA在通过过程中存活的机会。这可能是粪便中胰腺癌相关突变检测灵敏度低的原因之一。为了提高粪便样本中胰腺癌筛查的敏感性，我们建议设计和测试可摄取的聚合物包被纳米和微粒，它们将能够结合和保护DNA，包括胰腺癌DNA，直到它在粪便中排泄。我们的具体目标是：(1)利用KRAS G12D突变的胰腺肿瘤DNA，在体外优化颗粒在胆汁和胰液成分存在下的捕获和保护效率；（2a）将肿瘤DNA和颗粒喂给正常小鼠，测试粪便中KRAS突变的恢复情况；（2b）采用三敲除（KRAS-cre-p53）胰腺癌模型（KPC），检测粪便中KRAS突变检测敏感性的提高。该项目将对胰腺癌的诊断和监测产生重大影响。具体而言，本文提出的癌症DNA非侵入性采样方法可以提高高危人群胰腺癌早期筛查的可行性，可以发展成为一种成本效益高的早期筛查和监测工具。

DESCRIPTION (provided by applicant): Pancreatic cancer is often a fatal disease with 5-year survival rates of only 1-4%. Early detection can substantially reduce the mortality rate. Mutations of the KRAS oncogene (mainly in codon 12) are present in <90%-95% of cases of pancreatic cancer. KRAS mutations are not specific to pancreatic cancer, but early detection of these mutations in high-risk individuals, combined with the diagnostic follow-up, can save lives. Stool is a very attractive source of cancer-derived DNA that can be used for early screening. However, the hostile environment of the gastrointestinal tract composed of bile salts, DNases, and proteases reduces the chances that pancreatic cancer cells and cancer DNA will survive during the passage. This could be one of the reasons for low sensitivity of detection of pancreatic cancer-related mutations in stool. In order to improve the sensitivity of pancreatic cancer screening in stool samples, we propose to design and test ingestible polymer-coated nano- and microparticles that will be capable of binding and protecting DNA, including pancreatic cancer DNA, until it is excreted in stool. Our specific aims are: (1) Using pancreatic tumor DNA that has KRAS G12D mutation, optimize capture and protection efficiency by the particles in vitro in the presence of bile and pancreatic juice components; (2a) By feeding cancer DNA and the particles to normal mice, test the recovery of KRAS mutations in stool; (2b) Using triple knockout (KRAS-cre-p53) pancreatic cancer model (KPC), test the increase in sensitivity of detection of KRAS mutation in stool. This project will have a high impact on the diagnosis and monitoring of pancreatic cancers. Specifically, the proposed method for non-invasive sampling of cancer DNA can improve feasibility of early screening of pancreatic cancer in high-risk populations, and can be developed into a cost effective early screening and monitoring tool.