Neuroblastoma-derived secretory protein is a novel secreted factor overexpressed in neuroblastoma.
Secreted proteins such as growth factors, cytokines, and chemokines play important roles in tumor development. Through expression microarray and bioinformatic analysis, we discovered a novel secreted protein, neuroblastoma-derived secretory protein (NDSP). The NDSP gene is found on chromosome 1q25.2 and encodes a 167 amino acid protein with a putative signal peptide. Using real-time PCR and immunoblotting, we find that NDSP is specifically overexpressed in neuroblastoma at much higher levels than other adult and pediatric malignancies and normal tissues. NDSP is an 18-kDa protein that can be secreted by NDSP-transfected HEK-293T cells, as well as, neuroblastoma cell lines endogenously expressing NDSP. Inhibiting NDSP expression in neuroblastoma cell lines with retrovirally transduced NDSP small hairpin interfering RNA, sh-NDSP, results in decreased cellular proliferation and colony formation. We also find inhibited extracellular signal-regulated kinase (ERK)1/2 phosphorylation in the sh-NDSP cell line. Treating the parental cell line with MAP/ERK kinase 1/2 inhibitors, which diminish ERK1/2 phosphorylation, results in decreased cell proliferation. Culturing these transduced cells with recombinant NDSP, reintroducing NDSP overexpression in the knockdown cell line, or inducing Ras oncogene overexpression for constitutive ERK1/2 activation results in a reversal of the growth-inhibited phenotype and proliferation rates similar to the control cells. In addition, reintroduction of NDSP overexpression in the sh-NDSP cell line results in ERK1/2 phosphorylation similar to control. We conclude that NDSP is specifically overexpressed in neuroblastoma and actively secreted from tumor cells. Furthermore, NDSP serves as a growth factor for neuroblastoma tumor cells through activation of the ERK-mediated proliferation pathway.
Vasudevan
Sanjeev A
SA
Michael E DeBakey Department of Surgery, Dan L Duncan Cancer Center, Baylor College of Medicine, Houston, Texas 77030, USA.
Shang
Xiaoying
X
Shang
Xiaoyi
X
Chang
Shirong
S
Ge
Ningling
N
Diaz-Miron
Jose L
JL
Russell
Heidi V
HV
Hicks
M John
MJ
Ludwig
Andrew D
AD
Wesson
Catherine L
CL
Burlingame
Susan M
SM
Kim
Eugene S
ES
Khan
Javed
J
Yang
Jianhua
J
Nuchtern
Jed G
JG
D001483:Base Sequence; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002478:Cells, Cultured; D019295:Computational Biology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism*; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D014162:Transfection
C516780:FAM163A protein, human; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3