The Chemokine Receptor CXCR4 Strongly Promotes Neuroblastoma Primary Tumour and Metastatic Growth, but not Invasion

Abstract

Neuroblastoma (NB) is a heterogeneous, and particularly malignant childhood neoplasm in its higher stages, with a propensity to form metastasis in selected organs, in particular liver and bone marrow, and for which there is still no efficient treatment available beyond surgery. Recent evidence indicates that the CXCR4/CXCL12 chemokine/receptor axis may be involved in promoting NB invasion and metastasis. In this study, we explored the potential role of CXCR4 in the malignant behaviour of NB, using a combination of in vitro functional analyses and in vivo growth and metastasis assessment in an orthotopic NB mouse model. We show here that CXCR4 overexpression in non-metastatic CXCR4-negative NB cells IGR-NB8 and in moderately metastatic, CXCR4 expressing NB cells IGR-N91, strongly increased tumour growth of primary tumours and liver metastases, without altering the frequency or the pattern of metastasis. Moreover shRNA-mediated knock-down experiments confirmed our observations by showing that silencing CXCR4 in NB cells impairs in vitro and almost abrogates in vivo growth. High levels of CXCL12 were detected in the mouse adrenal gland (the primary tumour site), and in the liver suggesting a paracrine effect of host-derived CXCL12 on NB growth. In conclusion, this study reveals a yet unreported NB-specific predominant growth and survival-promoting role of CXCR4, which warrants a critical reconsideration of the role of CXCR4 in the malignant behaviour of NB and other cancers.

β-Arrestin1 and Distinct CXCR4 Structures Are Required for Stromal Derived Factor-1 to Downregulate CXCR4 Cell-Surface Levels in Neuroblastoma

“…Surface expression of CXCR4 has been shown to be low in several neuroblastoma cell lines (Carlisle et al, 2009). Nevertheless, CXCR4 overexpression is an indicator of worse outcomes for patients with neuroblastoma (Russell et al, 2004) and is also associated with site-specific metastasis particularly to the bone marrow (Geminder et al, 2001;Meier et al, 2007;Ben-Baruch, 2009). To mimic neuroblastoma with elevated CXCR4, and to facilitate our structure/function studies of CXCR4 downregulation, we overexpressed CXCR4 in SH-SY5Y cells using transient transfection of an expression plasmid encoding wild-type CXCR4 tagged with fluorescent YFP (CXCR4wt).…”

“…In addition to MYCN gene amplification, DNA ploidy changes, and expression of neurotrophin receptors (Vasudevan et al, 2005;Raffaghello et al, 2009;Huang et al, 2011;Davidoff, 2012), elevated expression of the CXCR4 CXC chemokine receptor is a marker and proposed drug target for high-risk neuroblastoma (Shim et al, 2009). CXCR4 expression is associated with neuroblastoma metastatic growth (Liberman et al, 2012), clinical presentation in bone marrow and liver (Geminder et al, 2001;Russell et al, 2004;Meier et al, 2007;Raffaghello et al, 2009;Zhao et al, 2012), and poor prognosis (Russell et al, 2004). Unfortunately, pharmacological targeting of CXCR4 is complicated by the widespread expression of CXCR4 on normal cells.…”

CXCL12 (SDF-1)/CXCR4 Pathway in Cancer

“…The CXCL12/CXCR4 axis is involved in several aspects of tumor progression including angiogenesis, metastasis, and survival (1,(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42). The bone marrow microenvironment facilitates the survival, differentiation, and proliferation of normal hematopoietic cells, malignant hematopoietic cells, and epithelial tumor cell bone metastasis.…”

Role of CXCL13-CXCR5 Crosstalk Between Malignant Neuroblastoma Cells and Schwannian Stromal Cells in Neuroblastic Tumors

“…Moreover, chemokines play a major role in tumor growth, angiogenesis, and invasion (10,11) in several cancers and neoplastic cells may express chemokine receptors (12). Over the last years, CCR1, CCR5, CCR6, CCR9, CXCR1, CXCR2, CXCR4, CXCR5, and CXCR6 were found expressed in neuroblastoma and it has been shown that CXCR4 is virtually expressed in all human neuroblastoma cell lines (13)(14)(15)(16).…”