Construction of orthotopic xenograft mouse models for human pancreatic cancer.

Animal models are indispensable for the study of tumorigenesis and the development of anti-cancer drugs for human pancreatic cancer. In the present study, two orthotopic xenograft mouse models were developed. AsPC-1 human pancreatic cancer cells were stably labeled with red fluorescent protein (RFP) and injected subcutaneously into nude mice. For the orthotopic tumor mass model, the formed subcutaneous tumors were cut into blocks and implanted into the pancreas of nude mice via laparotomy. For the Matrigel™ tumor block model, solidified Matrigel containing RFP-labeled AsPC-1 cells was cut into blocks and implanted into the pancreas of nude mice. A subcutaneous tumor xenograft model was used as a control. Tumor growth and metastasis were assessed using an in vivo fluorescence imaging system. Thirty-six days after implantation, all mice from the two orthotopic xenograft models (n=20 per group) and 55% of the subcutaneous xenograft mice (n=20) developed tumors. The tumor growth rate was significantly higher in the orthotopic models than that in the subcutaneous model (P<0.01). Metastasis to organs such as the liver was observed in the orthotopic tumor models. Histological examination showed that the tumors were poorly differentiated adenocarcinomas. In conclusion, two orthotopic xenograft mouse models of human pancreatic cancer were established; these exhibited greater tumor growth and metastasis than the subcutaneous xenograft mouse model.