PMC4462002_01
Imaging and Histopatological features of MB1. Axial CT (a) and axial conventional MR (b T2w, c FLAIR T2w, d T1w) images demonstrate a heterogeneous posterior fossa tumor in the left cerebellar hemisphere with mild surrounding edema (arrowheads) and significant mass effect on the fourth ventricle. The lesion shows a hypointense rim (white arrows) and a cystic component on its medial side (*). Apparent diffusion coefficient map (e) reveals restricted diffusion in solid tissue (black arrows). On the perfusion sequences (f) by arterial spin labeling, the tumor was depicted as a low perfusion area. (g) Neoplasm is composed of densely cells with round to oval shaped hyperchromatic nuclei with scanty cytoplasm. (h) Neoplastic cells are arranged in nodule surrounded by a reticular fiber network (Gomori stain)
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Fig1
Radiologic tumor assessment confirmed the presence of a renal neoplasm (78.1 x 42.2 x 62.8 mm) (Additional file 1: Figure S1a) with bilateral lung metastases (Additional file 1: Figure S1b). Neoadjuvant chemotherapy was started, according to SIOP WT 2001 protocol, obtaining a partial response on both primary tumor (44 x 33 x 22 mm) (Additional file 1: Figure S1c) and metastatic lesions. Cranio-spinal magnetic resonance imaging (MRI) confirmed a localized rounded heterogeneously enhancing mass with intralesional cystic components and perilesional edema (Fig. 1a-f). Such zones contained a population of small cells with rounded nuclei diagnostic of a desmoplastic/nodular medulloblastoma (Fig. 1g-h) without C/N-myc amplification evaluated by FISH analysis.
Imaging and Histopatological features of MB2. MRI. Axial T2-weighted image (a) and sagittal T1-weighted image (b) show a nodular mass originating from the vermis and bulging into the fourth ventricle. Apparent diffusion coefficient (ADC) map (c) shows lack of diffusion restriction. Perfusion weighted imaging (d) reveals hyperperfusion within the lesion. (e) Tumor is characterized by pleomorphic cells with large nuclei, prominent nucleoli and moderate eosinophilic cytoplasm. (f) Large cells show immunoreactivity for synaptophysin. (g) N-Myc oncogene amplification (green spots) detected in neoplastic nuclei (blue) and centromere 8 signals (red spots) using CEP8/BAC as FISH probes. Red arrow: N-Myc amplified cell. White arrow: N-Myc dyploid cell
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Fig2
MB2 (Fig. 2g and Fig. 5d). Moreover, differences were found in the expression of stem cell/differentiation genes: MB2 was characterized by low expression of lineage differentiation genes (ZIC1, BMP2, GFAP, GABRA6) (Fig. 5e) accompanied by expression of stemness genes, such as PROM1 and C-MYC (Fig. 5d), when compared to MB1.
Genetic Analyses. Direct sequencing data relative to the indicated region of BRCA2 gene demonstrating the biallelic mutations c.2944_2944delA exon 11 and c.658_659delGT exon 8 in patient's blood (a) and tumor (b), present in mother's blood (c) and father's blood (d) respectively. MUT: mutated case, WT: wild type case. (e) Family pedigree: closed symbol: affected with cancer, open symbol: unaffected with cancer. The type of cancer and age at presentation are given under the symbol. Arrow: proband, blue plus sign: BRCA2 c.658_659delGT exon 8 mutation, red plus sign: BRCA2 c.2944_2944delA exon11 mutation. Pro: prostate cancer, Pan: pancreatic cancer, Ov: ovarian cancer, CNS: central nervous system tumor, Gas: Gastric cancer, WT: Wilms Tumor, MB: Medulloblastoma
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Fig3
Genebank, NM_000059.1. By this mean, we revealed a compound heterozigosity for two distinct framshift mutations: the already described c.658_659delGT (p.Val220Ilefs) mutation on BRCA2 exon 8, and a previously unknown c.2944_2944delA (p.Ile982Tyrfs) mutation on BRCA2 exon 11 (Fig. 3)a and b, both of which are predicted to lead to truncated BRCA2 proteins. Genetic testing of the parents confirmed they both were heterozygous carriers; in particular, the father carried the c.658_659delGT mutation, while the mother carried the c.2944_2944delA mutation (Fig. 3c and d). The original donor of the new mutation could be the mother's maternal grandfather affected with pancreatic cancer, which belongs to the spectrum of FA/BRCA-associated tumors (Fig. 3e). Overall, the genealogical chart was characterized by a low occurrence of tumors both in paternal and maternal families and in particular by the absence of breast and ovarian cancer cases (Fig. 3e).
PMC4462002_02
Imaging and Histopatological features of MB2. MRI. Axial T2-weighted image (a) and sagittal T1-weighted image (b) show a nodular mass originating from the vermis and bulging into the fourth ventricle. Apparent diffusion coefficient (ADC) map (c) shows lack of diffusion restriction. Perfusion weighted imaging (d) reveals hyperperfusion within the lesion. (e) Tumor is characterized by pleomorphic cells with large nuclei, prominent nucleoli and moderate eosinophilic cytoplasm. (f) Large cells show immunoreactivity for synaptophysin. (g) N-Myc oncogene amplification (green spots) detected in neoplastic nuclei (blue) and centromere 8 signals (red spots) using CEP8/BAC as FISH probes. Red arrow: N-Myc amplified cell. White arrow: N-Myc dyploid cell
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Fig2
MB2 (Fig. 2g and Fig. 5d). Moreover, differences were found in the expression of stem cell/differentiation genes: MB2 was characterized by low expression of lineage differentiation genes (ZIC1, BMP2, GFAP, GABRA6) (Fig. 5e) accompanied by expression of stemness genes, such as PROM1 and C-MYC (Fig. 5d), when compared to MB1.
Molecular characterization of MB1 and MB2. Histograms showing mRNA levels of the indicated genes in MB1 (a) and MB2 (b) compared to normal cerebella (average of n = 7) as control (CTR). Genes are grouped and depicted in different colors, depending on the molecular subgroups, which they identify (SHH, WNT, GROUP 3, GROUP 4). The values of Relative Quantification are expressed in log10 scale
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Fig4
Gene expression analysis of MB1 and MB2. Histograms show mRNA levels of the indicated genes in MB1 and MB2 compared to normal cerebella (average of n = 7) as control (CTR). In detail (a) GLI family members; (b) Sonic Hedgehog pathway (Hh) molecules and direct targets. (c) Cyclins. (d) Myc genes and Stemness molecules; (e) Differentiation molecules; (f) Epigenetic modifiers. The values of Relative Quantification are expressed in linear scale for panels (a), (c), (d), (e) and (f) and log scale for panel (b)
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Fig5
MB2 was characterized by higher levels of EZH2, which trimethylates histone 3 lysine 27 (H3K27me3), concurrently with down regulation of the lysine demethylase 6A (KDM6A), which removes the same repressive mark on chromatin (Fig. 5e).
Heatmap and results of an unsupervised hierarchical clustering derived from the -DCt values of the analyzed genes in MB1 and MB2 (Case FA) and in adult (n = 4, A1, A2, A3, A4), childhood (n = 4, Ch1, Ch2, Ch3, Ch4) and infant (n = 4, I1, I2, I3, I4) SHH-MBs. Nodal numbers indicate bootstrap values obtained by resampling the data
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Fig6
MBs. Moreover, our analysis showed that hemispheric MB1 (diagnosed under 3 years of age) clustered with adult/childhood MBs (Fig. 6), while vermian MB2 (diagnosed after 3 years of age) clustered with infant SHH MBs (Fig. 6).
PMC4462002_03
Gene expression analysis of MB1 and MB2. Histograms show mRNA levels of the indicated genes in MB1 and MB2 compared to normal cerebella (average of n = 7) as control (CTR). In detail (a) GLI family members; (b) Sonic Hedgehog pathway (Hh) molecules and direct targets. (c) Cyclins. (d) Myc genes and Stemness molecules; (e) Differentiation molecules; (f) Epigenetic modifiers. The values of Relative Quantification are expressed in linear scale for panels (a), (c), (d), (e) and (f) and log scale for panel (b)
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Fig5
MB2 was characterized by higher levels of EZH2, which trimethylates histone 3 lysine 27 (H3K27me3), concurrently with down regulation of the lysine demethylase 6A (KDM6A), which removes the same repressive mark on chromatin (Fig. 5e).
Fanconi Anemia Pathway. Endogenous and exogenous agent cause interstrand crosslink lesions (ICL). When an ICL occurs, the replication fork is stalled and the FA pathway is activated with the recruitment of the FA core complex (FANCA, B, C, E, F, G, L, and M). FANCL ubiqiuitinates the FANCD2-FANCI (ID2) complex that guides the nucleolytic incisions and translesion synthesis repair events by "unhooking" the ICL. This allows the homologous recombination repair through FANCD1/BRCA2, FANCJ/BRIP1, FANCN/PALB2, FANCO/RAD51C, and FANCS/BRCA1. Yellow stars highlight FA/HR repair molecules that have been found genetically inactivated in FA patients with medulloblastoma. BCCIP is a BRCA2 interacting protein which is able to induce medulloblastoma growth when genetically loss in concomitance with p53 deletion (See text). Readapted from
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Fig7
The complex then "unhooks" ICL, allowing homologous recombination repair by FANCD1/BRCA2, FANCJ/BRIP1, FANCN/PALB2, FANCO/RAD51C, and FANCS/BRCA1 (Fig. 7). Thus, deleterious mutations in one of the members of the homologous recombination machinery could lead to MB onset (Fig. 7).