Vol. 273, Issue 1, 39-44, January 2, 1998
Proximal Promoter Sequences Mediate Cell-specific and Elevated
Expression of the Favorable Prognosis Marker TrkA in Human
Neuroblastoma Cells
Baochong B.
Chang
,
Stephan P.
Persengiev
,
Juana G.
de
Diego§,
Maria P.
Sacristan§,
Dionisio Martin
Zanca§, and
Daniel
L.
Kilpatrick
From the
Physiology Department, University of
Massachusetts Medical Center, Worcester, Massachusetts 01655 and
§ Instituto de Microbiologia Bioquimica, Universidad de
Salamanca, Avenida Campo Charro s/n, 37007, Salamanca, Spain
The nerve growth factor receptor, TrkA, has a
critical role in the survival, differentiation, and function of neurons
in the peripheral and central nervous systems. Recent studies have
demonstrated a strong correlation between abundant expression of TrkA
and a favorable prognosis of the pediatric tumor, neuroblastoma. This correlation suggests that TrkA may actively promote growth arrest and
differentiation of neuroblastoma tumor cells and may be an important
therapeutic target in the treatment of this disease. In the present
study, we have examined the mechanistic basis for TrkA gene expression
in human neuroblastoma cells. Northern blotting and nuclear run-on
analyses demonstrated that transcription is a primary determinant of
both cell-specific and variable expression of the TrkA gene in
neuroblastoma cell lines that express it to different degrees.
Cell-specific and variable transcription in neuroblastoma cells was
recapitulated by transient transfection of TrkA promoter-luciferase
reporter constructs, and regulatory sequences mediating these processes
were localized to a 138-base pair region lying just upstream of the
transcription initiation region. This neuroblastoma regulatory region
formed multiple DNA-protein complexes in gel shift assays that were
highly enriched in neuroblastoma cells exhibiting abundant TrkA
expression. Thus, TrkA-positive neuroblastoma cells are distinguished
by differential expression of putative transcription factors that
ultimately may serve as targets for up-regulating TrkA expression in
tumors with poor prognosis.
Copyright © 1998 by The American Society for Biochemistry and Molecular Biology, Inc.