Department of Orthopedic Surgery, Qilu Hospital, Shandong University, Jinan, Shandong 250014, P.R. China.
Department of Emergency Surgery, Qilu Hospital, Shandong University, Jinan, Shandong 250014, P.R. China.
Oncol Rep. 2016 Oct;36(4):1973-80. doi: 10.3892/or.2016.4991. Epub 2016 Aug 2.
The development of chemoresistance is closely linked to the plateau of the survival rate in osteosarcoma (OS) patients. CD133-positive (CD133+) OS cells are known as cancer stem cells (CSCs) in OS and exhibit the characteristic of chemoresistance. In this study, CD133+ and CD133‑negative (CD133‑) MG‑63 cells were isolated by magnetic activated cell sorting (MACS). We verified that CD133+ MG‑63 cells were more resistant to cisplatin (CDDP) than CD133‑ MG‑63 cells. DNA‑dependent protein kinase catalytic subunit (DNA‑PKcs) and P‑glycoprotein (P‑gp) were expressed at higher levels in the CD133+ MG‑63 cells compared with those levels in the CD133‑ MG‑63 cells, whereas downregulation of DNA‑PKcs by small interfering RNA (siRNA) decreased chemoresistance to CDDP and P‑gp expression at the mRNA and protein levels in these cells. This indicated that DNA‑PKcs was correlated with P‑gp expression in the CD133+ MG‑63 cells. The Akt/NF‑κB pathway was hyperactivated in the CD133+ MG‑63 cells, whereas inhibition of the Akt/NF‑κB pathway downregulated P‑gp expression. In addition, downregulation of DNA‑PKcs suppressed the activity of the Akt/NF‑κB pathway. These results revealed that downregulation of DNA‑PKcs could decrease P‑gp expression via suppression of the Akt/NF‑κB pathway in CD133+ MG‑63 cells. Therefore, inhibition of DNA‑PKcs decreases P‑gp expression and sensitizes OS CSCs to chemotherapeutic agents in vitro, which needs to be further validated in vivo.
耐药性的发展与骨肉瘤（OS）患者生存率的停滞密切相关。CD133 阳性（CD133+）骨肉瘤细胞被认为是骨肉瘤中的癌症干细胞（CSC），具有耐药性的特征。在本研究中，通过磁激活细胞分选（MACS）分离 CD133+和 CD133-（CD133-）MG-63 细胞。我们验证了 CD133+MG-63 细胞比 CD133-MG-63 细胞对顺铂（CDDP）更耐药。与 CD133-MG-63 细胞相比，CD133+MG-63 细胞中 DNA 依赖性蛋白激酶催化亚基（DNA-PKcs）和 P-糖蛋白（P-gp）的表达水平更高，而通过小干扰 RNA（siRNA）下调 DNA-PKcs 可降低这些细胞对 CDDP 的耐药性，并降低 P-gp 的表达水平。这表明 DNA-PKcs 与 CD133+MG-63 细胞中的 P-gp 表达相关。Akt/NF-κB 通路在 CD133+MG-63 细胞中被过度激活，而抑制 Akt/NF-κB 通路可下调 P-gp 的表达。此外，下调 DNA-PKcs 可抑制 Akt/NF-κB 通路的活性。这些结果表明，下调 DNA-PKcs 通过抑制 Akt/NF-κB 通路可降低 CD133+MG-63 细胞中 P-gp 的表达。因此，抑制 DNA-PKcs 可降低 P-gp 的表达，并使 OS CSCs 在体外对化疗药物敏感，这需要在体内进一步验证。
