CD133+/CD44+ prostate cancer stem cells exhibit embryo-like behavior patterns

Cancer stem cells (CSCs), which act as an important bridge between cancer formation and embryonic development, represent a small population associated with tumor initiation, drug resistance, metastasis and recurrence. CSCs have the ability to form spheroids in three-dimensional culture systems. Tumor spheroids derived from CSCs with symmetric and asymmetric division patterns were found to contain highly heterogeneous cell groups. The biological behavior patterns which some CSCs display serve as an important bridge between cancer formation and embryonic development. The cell population in the DU-145 prostate cancer cell line with surface markers CD133+/CD44+ was isolated by FACS. Prostate spheroids were formed by using agarose-coated plates. The morphological characteristics of the cell population within spheroid structure and the expression of Ki-67 and Caspase-3 were investigated by histochemical methods. In this study, we observed that CD133+/CD44+ prostate CSCs form different spheroid structures as well as normal spheroid structures: i) some spheroid structures formed with a highly transparent zone on the outer part of the spheroid, in addition to the normal spheroidal zones and ii) spheroidal structures obtained from prostate CD1334+/CD44+ CSCs that share the same microenvironment are hollow spheres similar to the blastula-like structure in the embryo. These spheroidal structures exhibiting embryo-like properties indicate that the expression of embryonic factors might be reiterated in CSCs. Further investigation of the formation mechanism of the transparent zone and the hollow sphere will shed light on the embryonic origin of prostate cancer and the design of new therapeutic strategies.