Tropism of cancer stem cells to a specific distant organ.

BACKGROUND Patients diagnosed with pancreatic cancer have a high mortality rate relating to the highly malignant and refractory nature of their disease, and reputedly linked to the presence of cancerous pancreatic stem cells. These stem cells are believed to be deeply involved in distant metastasis. Therefore, the present study examined whether pancreatic cancer stem cells (CSCs) exhibit organ-specific migration patterns during metastasis. MATERIALS AND METHODS Pancreatic cancer cells derived from primary tumors isolated from a mouse model of pancreatic cancer were subcutaneously injected into wild-type mice to form tumor allografts. Allografts were isolated and dissociated into single cells prior to cell sorting using flow cytometry. Sorted cancer cells were injected into the tail vein or spleen of recipient wild-type mice, and analyzed for engraftment three weeks post-transplantation. RESULTS Pancreatic cancer cells metastasized either to the liver or lungs. Furthermore, we compared the number and size of metastatic foci in the liver and lungs; metastatic liver foci were larger compared with those in the lungs. CONCLUSION Our results showed that pancreatic CSCs metastasize to distinct organs with direct access to the transplantation site via the circulation. Clarifying the interaction between pancreatic CSCs and the liver microenvironment will lead to improved prognosis and treatments for pancreatic cancer.