Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a high incidence of distant metastasis. Recent studies have shown that cancer stem cells (CSCs) are important in cancer cell growth, invasion, metastasis, and recurrence. Several studies have revealed some CSC-specific markers for PDAC, such as CD133, CD24, CD44, CXCR4, ESA, and nestin. Some evidence also suggests that PDAC progresses through a multistep process comprised of noninvasive precursor lesions known as pancreatic intraepithelial neoplasias (PanINs). The reports of CSCs in PanINs are limited. We performed a comprehensive analysis of the expression of CSC markers in PDACs, PanINs, and normal pancreatic tissues. Materials & Methods: CD24, CD44, ESA, CD133, CXCR4, and nestin were used as CSC markers. Human PDACs (n=67), PanIN-1 (n=35), PanIN-2 (n=52), PanIN-3 (n=18), and normal pancreatic tissues (n=54), which were obtained from patients who underwent surgical operations in the surgical department of Nippon Medical School, were used for immunohistochemical analysis. Human PDAC cell lines, PANC-1, KLM-1, and MIA PaCa-2, were used for flow cytometric assays and quantitative RT-PCR analysis. Results: Regarding the clinicopathological features, the positivity of CD44 and CD133 showed significant correlations for UICC classifications and histological features In the survival analysis, CD133-positive PDACs led to a significantly poorer prognosis. In the immunohistochemical analysis, CD24, CD44, ESA, CXCR4, and nestin showed a gradual increase of positivity along with the grades of PanINs. Flow cytometric assays and RT-PCR analysis confirmed the expression profile in PDAC. Conclusion: CSC markers were expressed to various extents in PDAC, and the expression of CD133 and CD44 was correlated with the prognosis and stage. Furthermore, CSC markers showed a gradual increase along with the grades of PanINs; therefore, CSC may be involved in the carcinogenesis of PDAC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 412. doi:1538-7445.AM2012-412