MYCN-non-amplified metastatic neuroblastoma with good prognosis and spontaneous regression: a molecular portrait of stage 4S

Abstract

Stage 4 neuroblastoma (NB) are heterogeneous regarding their clinical presentations and behavior. Indeed infants (stage 4S and non-stage 4S of age <365days at diagnosis) show regression contrasting with progression in children (>365days). Our study aimed at: (i) identifying age-based genomic and gene expression profiles of stage 4 NB supporting this clinical stratification; and (ii) finding a stage 4S NB signature. Differential genome and transcriptome analyses of a learning set of MYCN-non amplified stage 4 NB tumors at diagnosis (n=29 tumors including 12 stage 4S) were performed using 1Mb BAC microarrays and Agilent 22K probes oligo-microarrays. mRNA chips data following filtering yielded informative genes before supervised hierarchical clustering to identify relationship among tumor samples. After confirmation by quantitative RT-PCR, a stage 4S NB's gene cluster was obtained and submitted to a validation set (n=22 tumors). Genomic abnormalities of infant's tumors (whole chromosomes gains or loss) differ radically from that of children (intra-chromosomal rearrangements) but could not discriminate infants with 4S from those without this presentation. In contrast, differential gene expression by looking at both individual genes and whole biological pathways leads to a molecular stage 4S NB portrait which provides new biological clues about this fascinating entity.

Figure 1

Supervised hierarchical clustering of stage 4 NB comparing: (a) stage 4S NB to non‐stage 4S NB (124 significant genes), (b) stage 4S to [1yr−] stage 4 NB (45 significant genes). Each row represents a single gene and each column a tumor. Tumors #: 1–12, 4S; 13–20, [1yr−]; 21–29, [1yr+]. As shown in the color bar, red and green indicate up and down expressions, respectively, black no change, and gray no data available. Red arrow points #19 [1yr−] stage 4 NB tumor with a 4S’ profile suggesting an atypical stage 4S clinical presentation.

Figure 2

Expression profiling of top genes selected using gene classifier and S.B.I.M.E. analysis in each individual tumor of the patients cohort. For a given gene, the value of each individual bar of histogram represents the log ratio of the tumor expression signal as compared to that of the pool. Student's test yielded 2 p values, respectively 4s vs non‐4s and 4s vs [1yr−], as indicated in brackets. Tumors #: 1–12, 4S (blue bars); 13–20, [1yr−] (yellow bars); 21–29, [1yr+] (hatched bars). # 10, 11 & 12 tumors are in regression (*). Red arrow points #19 [1yr−] stage 4 NB tumor. a: GABRR2 [7 10−4; 10−4], b: ULBP3 [4 10−4; 3 10−3]; c: TSLP1[3 10−4; 1.5 10−2]; d: NFYA [9 10−4; 3 10−4]; e: PBX3 [4 10−5; 6 10−4]; f: HBP1 [4 10−4; 7 10−3]; g: HADHB [9 10−3; 7 10−2]; h: HMGCL [4 10−3; 10−1].