Heterogeneity of neuroblastoma cell lines in insulin‐like growth factor 1 receptor/Akt pathway‐mediated cell proliferative responses

Abstract

Insulin-like growth factor 1 receptor (IGF-1R) is critical for cancer cell proliferation; however, recent clinical anti-IGF-1R trials did not show clear clinical benefit in cancer therapy. We hypothesized that IGF-1R signaling-mediated proliferative response is heterogeneous in neuroblastoma (NB) cells, and analyzed the cell growth of 31 NB cell lines cultured in three different media, including Hybridoma-SFM medium (with insulin) and RPMI1640 with ⁄ without 10% FBS. Three growth patterns were found. In response to IGF and insulin, cell proliferation and Akt phosphorylation were upregulated in 13 cell lines, and suppressed by MK2206 (Akt inhibitor) and picropodophyllin (IGF-1R inhibitor). Interestingly, 3 of these 13 cell lines showed Akt self-phosphorylation and cell proliferation in RPMI1640; their proliferation was downregulated by anti-IGF-1 or anti-IGF-2 neutralizing antibody, suggesting the existence of an autocrine loop in the IGF-1R ⁄ Akt pathway. Eighteen NB cell lines did not proliferate in RPMI1640, even though Akt phosphorylation was upregulated by IGF and insulin. Based on the heterogeneous response of the IGF-1R ⁄ Akt pathway, the 31 NB cell lines could be classified into group 1 (autocrine IGF-mediated), group 2 (exogenous IGF-mediated) and group 3 (partially exogenous IGF-mediated) NB cell lines. In addition, group 3 NB cell lines were different from group 1 and 2, in terms of serum starvation-induced caspase 3 cleavage and picropodophyllin-induced G2 ⁄ M arrest. These results indicate that the response of the IGF-1R ⁄ Akt pathway is an important determinant of the sensitivity to IGF-1R antagonists in NB. To our knowledge, this is the first report describing heterogeneity in the IGF-1R ⁄ Aktmediated proliferation of NB cells. (Cancer Sci 2013; 104: 1162-1171 N euroblastoma (NB), a malignant tumor that originates from the sympathetic nervous system, is one of the most frequent pediatric solid tumors.(1) NB is characterized by heterogeneous clinical behaviors, tumor invasiveness being different according to age and anatomic stage at diagnosis. The tumor is sometimes completely curable and may even regress spontaneously, especially in younger children.(2) Heterogeneity of the tumors depends on the degree of morphological differentiation and on histopathology. Insulin and insulin-like growth factors (IGF, including IGF-1 and 2) belong to a family of mitogenic growth factors. IGF, insulin, and their receptors are involved in normal growth and differentiation of most tissues. The biological actions of both IGF and insulin can be mediated by the IGF-1 receptor (IGF-1R), a transmembrane heterotetramer, which is involved in mitogenic, anti-apoptotic and oncogenic transforming responses.(4,5) The functional IGF-1R contains two extracellular a-subunits and two intracellular b-subunits that form a heterotetrameric complex. The structural homology of IGF-1R and insulin receptor (IR) allows formation of hybrid receptors (hybrid-R) in which an IGF-1R chain is connected to an IR chain. Ligand interaction with a-...

Genomic Copy Number Profiling Using Circulating Free Tumor DNA Highlights Heterogeneity in Neuroblastoma

“…Indeed, IGF1R signaling, which plays an important role in cancer cell proliferation, has been shown to play a role in the neuroblastoma malignant phenotype (41)(42)(43)(44). Furthermore, in 2 cases, an alteration targeting TERT, shown recently to characterize aggressive high-risk neuroblastoma (45,46), was identified in the cfDNA, with one case harboring this alteration also in the metastatic tumor cells of the bone marrow but not in the primary neuroblastoma.…”

A dual‐specific anti‐IGF‐1/IGF‐2 human monoclonal antibody alone and in combination with temsirolimus for therapy of neuroblastoma

“…Notably, the sensitivity to m708.5 correlated with the high expression of IGF‐1R and/or IR‐A; however, this sensitivity to m708.5 was not uniform. Recent studies suggested that neuroblastoma cells were heterogeneous in their IGF‐1R pathway‐mediated cell proliferation . Constitutive activity of downstream signals ( e.g ., PI3K/Akt) independent of the IGF‐1R or IRA pathways could explain part of the heterogeneity of response between neuroblastoma cell lines.…”

“…Recent studies suggested that neuroblastoma cells were heterogeneous in their IGF-1R pathway-mediated cell proliferation. 36 Constitutive activity of downstream signals (e.g., PI3K/Akt) independent of the IGF-1R or IRA pathways could explain part of the heterogeneity of response between neuroblastoma cell lines. In vivo, m708.5 alone (4 mg/kg/dose, twice weekly for 3-4 weeks) significantly delayed neuroblastoma growth.…”

Picropodophyllin inhibits the growth of Ewing's sarcoma cells through the insulin-like growth factor-1 receptor/Akt signaling pathway

“…Numerous molecular studies have demonstrated that the Akt signal transduction cascade usually participates in ES cell progression, cell apoptosis, cell proliferation and drug susceptibility (32)(33)(34). As an IFG-1R inhibitor, PPP was found to have Akt inhibitory effects in neuroblastoma cell lines (35). Furthermore, the efficacy of PPP against multiple myeloma has also been demonstrated (31).…”