Establishment of pancreatic cancer patient-derived xenograft models and comparison of the differences among the generations.

Tumor samples of pancreatic ductal adenocarcinoma patients, who underwent resection surgery, were implanted into NOD/SCID mice to construct pancreatic cancer patient-derived xenograft (PDX) models and explore the biological changes in the different generations of PDXs. Ten PDXs were successfully generated, and the tumor formation rate of F1 PDXs was found to be 38.46%, which was lower than F2 (77.78%) and F3 (71.43%) PDXs. In addition, latent periods of tumorigenesis of F2 and F3 PDXs were significantly shorter, compared to that in F1 PDXs (P<0.05). Comparison of H&E staining of tumor tissue from primary pancreatic cancer and PDXs showed that all three generations of PDXs had similar histopathology to primary pancreatic cancer, indicating that PDXs may well reproduce the histological patterns of primary human cancer. Besides, Ki67 expression was increased in all three generations of PDXs compared to primary tumors of patients, and additionally, EpCAM expression was increased in F3 PDXs. These results were corroborated by the real-time qPCR and western blot results. Therefore, we concluded that PDXs are able to preserve the differentiation degree, morphological characteristics, and structural features of tumor cells. Furthermore, the latent periods of tumorigenesis are shortened after the first generation, which may be attributed to an increase in expression levels of tumor promoters such as Ki67 and EpCAM. PDX models may become an efficient tool for pancreatic cancer research.