Abstract
The aim of the present study was to investigate the effect of programmed cell death 1 (PD-1) on osteosarcoma (OD) stem cells and T cells, and to determine their correlation. OS stem cells were sorted and identified from OS MG63 cells. Flow cytometry was used to detect the PD-1 expression of the OS tumor stem cell membrane surface. The expression of PD-1 mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR). MTT was used to detect the effect of PD-1 signals on T-cell proliferation. The results indicated that the cancer cells (cultured in DMEM medium containing 10% fetal bovine serum) exhibited clear proliferation within 1 week of cell culture, which showed their strong proliferation and aggressive ability. The formation of tumor cell spheres was dependent on the support of serum nutrition. The proliferation of MG63 cells in the serum culture medium was significantly higher than the number of OS cell spheres in serum-free suspension culture (P<0.05). Pluripotent stem cells in cancer cell spheres exhibited significantly higher cluster of differentiation 133 expression compared with the MG63 cells. The PD-1 expression levels of the cancer cell spheres was significantly increased compared with the MG63 cells, which is consistent with the results of the RT-PCR. In conclusion, the MG63 cell line possesses the features of OS stem cells. The MG63 cell line can express the certain cancer-associated cell markers. The expression of PD-1 in spheres was also increased significantly compared to the MG63 cells, which can reduce the immune function of patients and may be closely associated with the occurrence and development of tumors.