Kaplan-Meier curves for OS rates.

<p>OS rates were compared between CC and any G (GC or GG) for the SNP <i>IL-6</i>–174 in (A) all patients, (B) in not <i>MYCN</i> amplified patients, (C) in high-risk patients and (D) not <i>MYCN</i> amplified high-risk patients.</p

Characteristics of NB patients stratified per <i>IL-6</i> -176 (G>C) SNP genotype.

<p>N.A.  =  not available.</p>a<p>p-values and ORs from comparison of allelic frequencies.</p>b<p>p-values and ORs from comparison of genotype frequencies (GG/GC vs CC).</p>c<p>p-values and ORs from comparison of stage 1+2 patients vs stage 3+4 patients.</p

Test for independent statistical significance of −174 <i>IL-6</i> SNP after adjustment for NB risk factors.

<p>HR, hazard ratio; CI, confidence interval; C-index, concordance index.</p>a<p>C-index calculated including in the model only the NB risk factor (Age or MYCN or INSS stage 4).</p>b<p>C-index calculated including in the model the NB risk factor and <i>IL-6</i> SNP.</p

Case-Control study of <i>IL-6</i>–176 (G>C) SNP.

a<p>P-value and OR obtained by Armitage's trend test.</p

SNP genotype correlation to <i>IL-6</i> gene expression and NB outcome.

<p><i>In silico</i> and qRT-PCR analysis of <i>IL-6</i> mRNA expression in (A) 198 LCLs and (B) 31 NB tumors, respectively, stratified according to the SNP <i>IL-6</i>–174. (C) Luciferase report gene assay carried out in HEK293 cells. Data shown in percentage are the mean ± SD from three independent transfection experiments, each done in triplicate and compared with promoter less control. Kaplan-Meier analysis is shown, with individuals grouped by median of expression of <i>IL-6</i> for OS and Progression Free Survival (PFS) rates in (D and E) 88 NB patients and (F) only PFS for 102 INSS stage 4 patients with <i>MYCN</i> not amplified. OS data of Seeger dataset were not available.</p

Impact of Interleukin-6 –174 G>C Gene Promoter Polymorphism on Neuroblastoma

<div><p>Background</p><p>Common variants in DNA may predispose to onset and progression of neuroblastoma (NB). The genotype GG of single nucleotide polymorphism (SNP) rs1800795 (−174 G>C) in interleukin (IL)-6 promoter has been associated with lower survival of high-risk NB.</p><p>Result</p><p>To evaluate the impact of <i>IL-6</i> SNP rs1800795 on disease risk and phenotype, we analyzed 326 Italian NB patients and 511 controls. Moreover, we performed <i>in silico</i> and quantitative Real Time (qRT)-PCR analyses to evaluate the influence of the SNP on gene expression in 198 lymphoblastoid cell lines (LCLs) and in 31 NB tumors, respectively. Kaplan-Meier analysis was used to verify the association between <i>IL-6</i> gene expression and patient survival. We found that <i>IL-6</i> SNP is not involved in susceptibility to NB development. However, our results show that a low frequency of genotype CC is significantly associated with a low overall survival, advanced stage, and high-risk phenotype. The <i>in silico</i> (<i>p</i> = 2.61×10⁻⁵) and qRT-PCR (<i>p</i> = 0.03) analyses showed similar trend indicating that the CC genotype is correlated with increased level of <i>IL-6</i> expression. In report gene assay, we showed that the −174 C variant had a significantly increased transcriptional activity compared with G allele (<i>p</i> = 0.0006). Moreover, Kaplan-Meier analysis demonstrated that high levels of <i>IL-6</i> are associated with poor outcome in children with NB in two independent gene expression array datasets.</p><p>Conclusions</p><p>The biological effect of SNP <i>IL-6</i>–174 G>C in relation to promotion of cancer progression is consistent with the observed decreased survival time. The present study suggests that SNP <i>IL-6</i>–174 G>C may be a useful marker for NB prognosis.</p></div