Abstract 1725: The significance of c-Kit proto-oncogene in iCSC-derived PDAC model

Abstract Our study is focused on the generation of a novel pancreatic iPS-derived cancer stem cell line (iCSC), as a cutting-edge model of study for PDAC, and the significance of the proto-oncogene c-Kit in PDAC, using the new model of iCSC-derived PDAC generated in vivo. Pancreatic ductal adenocarcinoma (PDAC) is a neoplasia that originates within the pancreatic ducts. The mortality rate is high due to its rapid dissemination, the strong resistance to the radio and chemotherapy, along with the lack of prognostic approaches. Therefore, this highlights the urgent need to find novel therapies along with new pancreatic cancer markers towards the early detection of the primary stages of the PDAC. The iCSC cells were orthotopically transplanted into the pancreas of Balb/c nude mice. After a short-time course of 15 days, PDAC progression was recapitulated not only at the level of the tumour phenotype, but also with the corresponding invasion towards specific hepatic metastatic nodes. iCSC cells were obtained from iPS, following the procedure previously established by our group, where the reprogramming is accomplished exclusively through conditioned medium, without any genetic modification, which may represent a substantial tool to study fairly about the insights on the actual tumour microenvironment. In order to confirm these experiments are reproducible, iPS were cultured with different pancreatic cancer cell line -PK-8, KLM-1 and PK-59-conditioned medium. Histochemistry assay of the tumour developed in vivo demonstrated the effectiveness of the conversion from iPS into iCSC among the cell lines, generating stroma-rich ductal adenocarcinoma structures that resemble the human tumour phenotype. The tyrosine receptor c-Kit is expressed only during the embryonic pancreas differentiation, whereas adult pancreatic normal tissues lack the expression of the receptor. However in PDAC, its overexpression seems to be tightly correlated with the progression of the disease, and c-Kit has been suggested as a CSC marker. The overexpression of c-Kit receptor was observed at protein and mRNA expression level, in the primary cultures of iCSC-derived PDAC tumours. Interestingly, this overexpression is directly related to the tumour phenotype, being the most disrupted ductal structures those, which show the c-Kit over-expression. Additionally, CSC from the primary cultures of iCSC-derived PDAC were isolated by puromycin selection as well as sphere formation, and after 7 days of culture the mRNA expression levels of Pax4 appears to be up-regulated, suggesting that iCSC cells indeed may differentiate into a tissue-specific lineage. Hence, c-Kit might be a prominent candidate as a CSC marker in PDAC, and according to the current results we have generated a suitable PDAC model, which recapitulates the actual disease in a short-time course, and allows the study of the actual tumour microenvironment. Citation Format: Anna Sanchez Calle, Kenta Hoshikawa, Neha Nair, Marta Prieto-Vila, Arun Vaidyanath, Tomonari Kasai, Masaharu Seno. The significance of c-Kit proto-oncogene in iCSC-derived PDAC model. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1725.