Recent studies suggest that the ability to form and grow tumors specifically resides in a small cell population called cancer stem cells (CSCs). These studies were conducted mainly on various human cancers; however, isolation and characterization of stem cells from cholangiocarcinoma have not been attempted. The molecular markers CD24, CD44, CD34, and epithelial cell adhesion molecule (EpCAM) are widely used, individually or in combination, to characterize some types of CSCs. In this study, we used these markers to identify a subpopulation of cells in extrahepatic cholangiocarcinoma (ECC) with cancer stem/progenitor cell-like properties. We found that CD241 CD44 Extrahepatic cholangiocarcinoma (ECC), including perihilar and distal biliary tree carcinomas, is notoriously difficult to diagnose and treat, and is associated with extensive local tumor invasion, multidrug resistance and high mortality. 1,2 Despite advances in surgical and medical therapy, its survival rates have not improved significantly over recent decades. 3 Recent data suggest that cancer stem cells (CSCs) are critical for tumor initiation, progression and persistence, and metastasis.

The aim of this study was to investigate the effect of microRNA-20a on pancreatic carcinoma cell proliferation and invasion and to find a new effective treatment strategy for pancreatic carcinoma. MicroRNA-20a expression was determined in 10 matched normal pancreatic tissues and pancreatic carcinoma by in situ hybridization. Quantitative real-time RT-PCR was used to evaluate the expression of microRNA-20a in two pancreatic carcinoma cell lines (BxPC-3 and Panc-1) and immortal human pancreatic duct epithelial cell line H6C7. Proliferation and invasion capacity were analyzed for the cells with lentivirus-mediated overexpression of microRNA-20a both in vitro and in vivo. In addition, the regulation of signal transducer and activator of transcription proteins 3 (Stat3) by microRNA-20a was determined to elucidate the underlying mechanisms. The pancreatic cancer cell lines (Panc-1 and BxPC-3) stably overexpressing microRNA-20a showed reduced proliferation and invasion capacity in vitro and in vivo, compared with parental cells or cells transfected with a control vector. Furthermore, we found that microRNA-20a negatively regulated Stat3 protein expression in a dose-dependent manner without changing the Stat3 mRNA level and decreased the activity of a luciferase reporter construct containing the Stat3 3'-untranslated region. These results show that microRNA-20a regulates Stat3 at the post-transcriptional level, resulting in inhibition of cell proliferation and invasion of pancreatic carcinoma. It may open a new perspective for the development of effective gene therapy for pancreatic carcinoma.

These results prove that miR-17-5p negatively regulates Bim at the posttranscriptional level. We suggest that miR-17-5p inhibitor gene therapy would be a novel approach to chemosensitization for human pancreatic cancer.