Comparison of the characteristics of mesenchymal stem cells obtained from prostate tumors and from bone marrow cultured in conditioned medium.

Prostate cancer (PCa) is the most common type of cancer worldwide. Mesenchymal stem cells (MSCs) can also be utilized as 'tumor stromal cells', which are associated with invasive and metastatic malignant tumor cells. Our study aimed to investigate MSCs in prostate tumors and normal MSCs and evaluate their differential characteristics. Normal MSCs (BMMSCs) were isolated from the femur and tibia of normal mice; prostate tumor MSCs (PCa-MSCs) were obtained from prostate tumors implanted in mice. These two types of MSCs were induced to differentiate into adipocytes, bone cells and chondrocytes. Growth curves were used to analyze the growth ability of PCa-MSCs and BMMSCs. Tritium-labeled thymidine (3H-TdR) was used to evaluate cell proliferation of RM-1 stimulated by MSCs. The time taken for PCa-MSCs to reach 90% confluence was markedly shorter than that of BMMSCs (8-10 vs. 12-14 days). The differentiation ability of PCa-MSCs was similar to that described in previous reports. The growth ability of PCa-MSCs was significantly higher than that of BMMSCs. The proliferative activity of PCa-MSCs was also higher than that of BMMSCs. Our data showed that PCa-MSCs exhibit identical characteristics when compared with those of MSCs. Additionally, their proliferative activity and growth ability were significantly higher when compared with these values in BMMSCs, which appear to have an intrinsic, cell-specific capacity to localize to PCa. The possible role of PCa-MSCs in the process of PCa development requires further clarification.