PI3K and MAPK pathways mediate the BDNF/TrkB-increased metastasis in neuroblastoma.

Zhongyan Hua,Xiao Gu,Yudi Dong,Zhihui Liu,Zhihui Liu,Zhijie Li,Fei Tan,Carol J Thiele,Carol J Thiele

doi:10.1007/s13277-016-5433-z

Abstract

Brain-derived neurotrophic factor (BDNF) and its tyrosine kinase receptor TrkB have been reported to be associated with poor prognosis in neuroblastoma (NB) patients. Our previous studies indicated that BDNF activation of TrkB induces chemo-resistance through activation of phosphoinositide-3-kinase (PI3K)/Akt pathway. In this study, we investigated the role of BDNF/TrkB on metastasis in NB. A tetracycline-regulated TrkB-expressing NB cell line (TB3) was used. Scratch wound healing assay, Boyden chamber migration, and invasion assays were performed to study the migration and invasion of TB3 cells. A tumor xenograft model using SCID-Beige mice was utilized to detect the metastasis of NB tumors in vivo. Inhibitors of PI3K, MAPK, Akt, and mTOR were used. Western blotting was performed to study the expressions of P-Akt, P-Erk, and P-mTOR. Our results showed that in TrkB-expressing NB cells, BDNF treatment significantly increased gap closing (P < 0.01) in scratch wound healing assay, also significantly enhanced the numbers of migrating cells (P < 0.01) and invading cells (P < 0.01) in the Boyden chamber migration and invasion assays. In vivo, NB distant metastases were significantly increased in mice with TrkB-expressing xenograft tumors compared to those with non-TrkB-expressing tumors (P < 0.05). Pre-treatment with any of the inhibitors for PI3K (LY294002), MAPK (PD98059), Akt (perifosine), or mTOR (rapamycin) blocked the BDNF/TrkB-induced increases of cell migration and invasion in TB3 cells, and also blocked the BDNF/TrkB-induced expressions of P-Akt, P-Erk, and P-mTOR. These data indicated that BDNF/TrkB increased metastasis in NB via PI3K/Akt/mTOR and MAPK pathways, and BDNF/TrkB and the downstream targets may be potential targets for the treatment of NB metastasis.Electronic supplementary materialThe online version of this article (doi:10.1007/s13277-016-5433-z) contains supplementary material, which is available to authorized users.

Highlights

Neuroblastoma (NB) is one of the most common pediatric malignancies that derives from neural crest precursor cells
We have shown that adding Brain-derived neurotrophic factor (BDNF) to the cells could activate the tyrosine kinase, and further PI3K and MAPK pathways only in the TrkBexpressing cells (TET−), not the non-TrkB-expressing cells (TET+) [11]
Our previous studies have indicated that BDNF/TrkB induced chemo-resistance via PI3K/Akt pathway and MAPK pathway [9,10,11]; we and others have reported that inhibition of TrkB enhanced chemotherapeutic efficacy in NB in vitro and in vivo [13, 28]

Summary

Introduction

Neuroblastoma (NB) is one of the most common pediatric malignancies that derives from neural crest precursor cells. It is an extracranial solid tumor that most frequently occurs in adrenal gland [1,2]. Tumor spontaneous regression or differentiation happens in patients with low-risk disease, and surgery with little or no adjunctive therapy is effective for these patients [2,3]. While for patients with high-risk diseases, chemo-resistance and metastasis are the two main problems. Patients may initially response to chemotherapy, but chemoresistance would develop soon. Despite of multimodality chemotherapy and stem cell transplantation, satisfactory response still could not be achieved. The long-term survival rate of these patients is less than 40 % [2,3,4,5].

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Conclusion