PEST-containing nuclear protein mediates the proliferation, migration, and invasion of human neuroblastoma cells through MAPK and PI3K/AKT/mTOR signaling pathways

Dong-Dong Wu,Dan Lu,Shi-Yu Liu,Da-Yong Wang,Tao Li,Ya Hong,Hui-Bin Ning,Xin-Ying Ji,Xin-Ying Ji,Hui-Bin Ning,Jun-Ping Liu,Jun-Ping Liu,Jun-Feng Shi,Jun-Feng Shi,Jia Shang,Jia Shang,Ying-Ran Gao,Jian-She Wei,Jian-She Wei

doi:10.1186/s12885-018-4391-9

Abstract

BackgroundPEST-containing nuclear protein (PCNP), a novel nuclear protein, is involved in cell proliferation and tumorigenesis. However, the precise mechanism of action of PCNP in the process of tumor growth has not yet been fully elucidated.MethodsShRNA knockdown and overexpression of PCNP were performed in human neuroblastoma cells. Tumorigenic and metastatic effects of PCNP were examined by tumor growth, migration, and invasion assays in vitro, as well as xenograft tumor assay in vivo.ResultsPCNP over-expression decreased the proliferation, migration, and invasion of human neuroblastoma cells and down-regulation of PCNP showed reverse effects. PCNP over-expression increased protein expressions of cleaved caspase-3, cleaved caspase-8, cleaved caspase-9, and cleaved poly adenosine diphosphate-ribose polymerase, as well as ratios of B-cell lymphoma-2 (Bcl-2)-associated X protein/Bcl-2 and Bcl-2-associated death promoter/B-cell lymphoma-extra large in human neuroblastoma cells, however PCNP knockdown exhibited reverse trends. PCNP over-expression increased phosphorylations of extracellular signal-regulated protein kinase 1/2, p38, c-Jun N-terminal kinase, as well as decreased phosphorylations of phosphatidylinositol 3-kinase (PI3K), Akt, and mammalian target of rapamycin (mTOR), nevertheless PCNP knockdown exhibited opposite effects. Furthermore, PCNP over-expression significantly reduced the growth of human neuroblastoma xenograft tumors by down-regulating angiogenesis, whereas PCNP knockdown markedly promoted the growth of human neuroblastoma xenograft tumors through up-regulation of angiogenesis.ConclusionsPCNP mediates the proliferation, migration, and invasion of human neuroblastoma cells through mitogen-activated protein kinase and PI3K/AKT/mTOR signaling pathways, implying that PCNP is a therapeutic target for patients with neuroblastoma.

Highlights

PEST-containing nuclear protein (PCNP), a novel nuclear protein, is involved in cell proliferation and tumorigenesis
We further examined the effects of PCNP on tumor growth and angiogenesis in nude mice xenografted with human neuroblastoma
MRNA and protein levels of PCNP showed similar trends (Fig. 1b–d). These results indicate that PCNP over-expression and knockdown experiments have been successfully performed in human neuroblastoma cells

Summary

Introduction

PEST-containing nuclear protein (PCNP), a novel nuclear protein, is involved in cell proliferation and tumorigenesis. Neuroblastoma, a pediatric cancer of the developing sympathetic nervous system, is one of the most common solid tumors in infancy and early childhood [1,2,3]. It is well known that the PEST sequence functions as a proteolytic signal to target proteins for degradation via the proteasome pathway or calpain proteolysis [11, 14, 15]. A novel PEST-containing nuclear protein (PCNP) has been identified in the nucleus through database mining. PCNP and NIRF may be involved in the signaling pathway concerned with cell cycle regulation and/or genome stability [19]. The expression level of PCNP in neuroblastoma cells is unknown, and the effect of PCNP on the growth of neuroblastoma cells has not yet been elucidated

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Conclusion