Src kinase family inhibitor PP2 induces aggregation and detachment of neuroblastoma cells and inhibits cell growth in a PI3 kinase/Akt pathway-independent manner.
OBJECTIVE
Neuroblastoma (NB) is one of the most common extracranial solid tumors in children and is known for its clinical and biological heterogeneity. The aim of this study is to reveal the functional role of src family kinases in the biological behavior of NB by inhibiting their kinase activities with a specific inhibitor, PP2 (4-amino-5-(4-chloro-phenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine).


METHODS
NB cell lines (SH-SY5Y, IMR32, RT-BM-1, CHP134, NLF, and LA-N-5) were treated with 0.1-10 µM of PP2. Morphological changes, cell growth, and cell death were assessed, as well as all-trans retinoic acid (ATRA)-induced neuronal differentiation and epidermal growth factor (EGF)-induced proliferation.


RESULTS
At 24 h after PP2 treatment, NB cell lines showed drastic cell aggregation. PP2 also inhibited cell growth of NB in a dose-dependent manner. Apoptosis was detected in these cells. ATRA-induced neuronal differentiation of RT-BM-1 was not affected by PP2. PP2 reduced the proliferative effect of EGF. EGF-induced rapid activation of Akt, which was not blocked by PP2 treatment, suggesting that the cellular events triggered by PP2 were independent to PI3 kinase/Akt signaling pathway.


CONCLUSIONS
Our data suggests that src family kinases promote cell survival/proliferation and reduces cell aggregation of NBs. Src family kinase inhibitors may be good candidates for a novel molecular target therapy.
Department of Pediatric Surgery, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8677, Japan. hishiki@faculty.chiba-u.jp
Tomoro
T
Hishiki
Takeshi
T
Saito
Yoshiharu
Y
Sato
Tetsuya
T
Mitsunaga
Elena
E
Terui
Gen
G
Matsuura
Eriko
E
Saito
Ryohei
R
Shibata
Naoko
N
Mise
Yukiko
Y
Yokoyama
Hideo
H
Yoshida
D015153:Blotting, Western; D002449:Cell Aggregation / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D006801:Humans; D020287:In Situ Nick-End Labeling; D009447:Neuroblastoma / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000187:drug effects / Q000378:metabolism*; D011743:Pyrimidines / Q000494:pharmacology*; D019061:src-Family Kinases / Q000037:antagonists & inhibitors*
C412373:AG 1879; D011743:Pyrimidines; D019869:Phosphatidylinositol 3-Kinases; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt