Introduction: Dogs spontaneously develop prostate cancer (PC) like humans. Since most dogs with PC have a poor prognosis, they might represent a translational model for advanced PC in humans. Stem cell- derived 3D organoid culture could recapitulate organ structure and physiology. Using patient tissues, a human PC organoid culture system was established. A recent study showed that urine cells also possess the characteristics of stem cells. However, the urine cell- derived PC organoids have never been produced. We therefore gen-erated PC organoids using dog urine samples.
Material and Methods: After dogs were diagnosed with prostate tumor, urine samples were collected by catheterization and used for the organoid culture. The organoids were assessed microscopically (haematoxilin and eosin staining) and in terms of marker expression by means of immunofluorescence staining, immunohistochemical staining and flow cytometry. Additionally, mouse xenograft assay and cell viability assay were carried out.
Results: Urine organoids from each PC dog were successfully gen-erated. Each organoid showed cystic structures and resembled the epithelial morphology of the original tissue. Expression of an epithelial cell marker, E- cadherin and a myofibroblast marker, α- smooth muscle actin (SMA) was confirmed. The organoids also expressed a basal cell marker, CK5 and a luminal cell marker, CK8. CD49f- sorted basal cell organoids rapidly grew compared with CD24- sorted lumi-nal ones. The population of CD44- positive cells was the highest inboth organoids and the original urine cells. Injection of the organoids into immunodeficiency mice successfully formed tumor, which ex-hibited the features of the organoids. Treatment with a microtubule inhibitor, docetaxel, but not with a cyclooxygenase inhibitor, piroxi-cam, and an mTOR inhibitor, rapamycin, decreased the cell viability of organoids. Treatment with a Hedgehog signal inhibitor, GANT61, increased the radiosensitivity in the organoids.
Conclusions: These findings revealed that PC organoids using urine might become a useful tool to investigate the mechanisms of patho-genesis and treatment of canine PC. |
