Non-invasive sampling of DNA markers for pancreatic cancer screening

描述(申请人提供)：胰腺癌通常是一种致命的疾病，5年存活率只有1-4%。及早发现可以大大降低死亡率。KRAS癌基因突变(主要位于第12密码子)存在于90%-95%的胰腺癌病例中。KRAS突变并不是胰腺癌特有的，但在高危人群中及早检测到这些突变，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衍生DNA来源，可用于早期筛查。然而，由胆盐、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在传代过程中存活的机会。这可能是检测粪便中胰腺癌相关突变的灵敏度较低的原因之一。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能够结合和保护DNA(包括胰腺癌DNA)的可食用聚合物包裹的纳米和微米颗粒，直到它在粪便中排泄。我们的具体目标是：(1)利用具有KRAS G12D突变的胰腺癌DNA，在胆汁和胰液成分存在的情况下，优化体外颗粒的捕获和保护效率；(2a)通过给正常小鼠喂饲肿瘤DNA和颗粒，测试粪便中KRAS突变的恢复；(2b)利用三重敲除(KRAS-cre-p53)胰腺癌模型(KPC)，测试检测粪便中KRAS突变的灵敏度的提高。该项目将对胰腺癌的诊断和监测产生很大影响。具体地说，所提出的癌症DNA非侵入性采样方法可以提高在高危人群中早期筛查胰腺癌的可行性，并可以发展成为一种经济有效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.