Downregulation of nuclear protein-1 induces cell cycle arrest in G0/G1 phase in glioma cells in vivo and in vitro via P27.

Nuclear protein-1 (NUPR1), also named as p8 or Com1, has been since found overexpressed in several human malignant tumor cells, such as glioma. NUPR1 also regulates cell cycle progression, however, the role of NUPR1 in regulating glioma cell cycle remains poorly understood. Knockdown efficiency of U87 and U251 cells infected with the lentiviral vector was detected by quantitative real-time PCR and western blot in vitro and in vivo. Flow cytometry and western blot were used to explore a mechanism by which NUPR1 modulates cell cycle in U87 and U251 cells. Immunohistochemistry was applied to detect expression levels of P27, CDK2, and cyclin E in human glioma tissues with NUPR1 positive expression and tumorigenesis in nude mice. We confirmed that the downregulation of NUPR1 arrested the cell cycle in the G0/G1 phase in U87 and U251 cells in vitro. Furthermore, the expression level of P27 was increased, and CDK2 and cyclin E were decreased upon silencing NUPR1 expression in vitro and in vivo. In conclusion, the knockdown of NUPR1 induces cell cycle arrest in the G0/G1 phase in glioma cells via P27.