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Expression of the neuron-specific protein CHD5 is an independent marker of outcome in neuroblastoma.

Garcia I, Mayol G, Rodríguez E, Suñol M, Gershon TR, Ríos J, Cheung NK, Kieran MW, George RE, Perez-Atayde AR, Casala C, Galván P, de Torres C, Mora J, Lavarino C - Mol. Cancer (2010)

Bottom Line: Within NTs, CHD5 immunoreactivity was found restricted to differentiating neuroblasts and ganglion-like cells, and absent in undifferentiated neuroblasts and stromal Schwann cells.Correlation between protein and mRNA levels was found, suggesting transcriptional regulation of CHD5.Re-establishment of CHD5 expression induced by chemotherapy could be a surrogate marker of treatment response.

View Article: PubMed Central - HTML - PubMed

Affiliation: Developmental Tumor Biology Laboratory, Hospital Sant Joan de Déu, Fundación Sant Joan de Déu, Barcelona, Spain.

ABSTRACT

Background: The chromodomain, helicase DNA-binding protein 5 (CHD5) is a potential tumor suppressor gene located on chromosome 1p36, a region recurrently deleted in high risk neuroblastoma (NB). Previous data have shown that CHD5 mRNA is present in normal neural tissues and in low risk NB, nevertheless, the distribution of CHD5 protein has not been explored. The aim of this study was to investigate CHD5 protein expression as an immunohistochemical marker of outcome in NB. With this purpose, CHD5 protein expression was analyzed in normal neural tissues and neuroblastic tumors (NTs). CHD5 gene and protein expression was reexamined after induction chemotherapy in a subset of high risk tumors to identify potential changes reflecting tumor response.

Results: We provide evidence that CHD5 is a neuron-specific protein, absent in glial cells, with diverse expression amongst neuron types. Within NTs, CHD5 immunoreactivity was found restricted to differentiating neuroblasts and ganglion-like cells, and absent in undifferentiated neuroblasts and stromal Schwann cells. Correlation between protein and mRNA levels was found, suggesting transcriptional regulation of CHD5. An immunohistochemical analysis of 90 primary NTs highlighted a strong association of CHD5 expression with favorable prognostic variables (age at diagnosis <12 months, low clinical stage, and favorable histology; P < 0.001 for all), overall survival (OS) (P < 0.001) and event-free survival (EFS) (P < 0.001). Multivariate analysis showed that CHD5 prognostic value is independent of other clinical and biologically relevant parameters, and could therefore represent a marker of outcome in NB that can be tested by conventional immunohistochemistry. The prognostic value of CHD5 was confirmed in an independent, blinded set of 32 NB tumors (P < 0.001).Reactivation of CHD5 expression after induction chemotherapy was observed mainly in those high risk tumors with induced tumor cell differentiation features. Remarkably, these NB tumors showed good clinical response and prolonged patient survival.

Conclusions: The neuron-specific protein CHD5 may represent a marker of outcome in NB that can be tested by conventional immunohistochemistry. Re-establishment of CHD5 expression induced by chemotherapy could be a surrogate marker of treatment response.

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Chemotherapy-induced expression of CHD5 in 12 high risk NB tumors. (A) CHD5 immunoreactivity pre- and post-chemotherapy (400x); (B) Kaplan-Meier analysis for OS was performed using the mean between pre-treatment and post-treatment gene expression levels as cut-off to divide tumors which reactivate CHD5 and tumors that maintain low expression levels; (C) CHD5 transcript levels quantified by qRT-PCR: CHD5 expression levels (Black) at diagnosis, (Grey) post-chemotherapy. Fetal brain CHD5 expression represents normal neural tissue values.
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Figure 4: Chemotherapy-induced expression of CHD5 in 12 high risk NB tumors. (A) CHD5 immunoreactivity pre- and post-chemotherapy (400x); (B) Kaplan-Meier analysis for OS was performed using the mean between pre-treatment and post-treatment gene expression levels as cut-off to divide tumors which reactivate CHD5 and tumors that maintain low expression levels; (C) CHD5 transcript levels quantified by qRT-PCR: CHD5 expression levels (Black) at diagnosis, (Grey) post-chemotherapy. Fetal brain CHD5 expression represents normal neural tissue values.

Mentions: Tumor histology and gene expression can change with treatment as a result of important changes in cellular processes. We investigated the effects of induction chemotherapy (3 cycles) on CHD5 expression in 12 high risk NB cases with available paired diagnostic and post-chemotherapy tumor specimens for qRT-PCR and immunohistochemical analyses. At diagnosis all these tumors (2 locoregional and 10 stage 4 NB) displayed low CHD5 mRNA expression and negative immunostaining. Following induction chemotherapy, a significant increase of CHD5 transcript and CHD5 positive nuclear staining was detected in 6/12 specimens, together with therapy-induced morphological changes (increased cytoplasm and ganglion-like cell morphology) (Figure 4A and 4C; cases #1-6). All these patients achieved an initial complete or very good response to cytotoxic therapy (chemo- and radiation therapy). At the time of analysis, 5/6 patients were alive with a mean follow-up of 35.62 months (Figure 4B). One case, stage 4 MYCN amplified, progressed after a good initial response to chemotherapy and died of refractory bone marrow disease (Figure 4C; case #6). Bone marrow aspirate smears of this patient exhibited widespread tumor dissemination with CHD5 negative neuroblast aggregates (data not shown).


Expression of the neuron-specific protein CHD5 is an independent marker of outcome in neuroblastoma.

Garcia I, Mayol G, Rodríguez E, Suñol M, Gershon TR, Ríos J, Cheung NK, Kieran MW, George RE, Perez-Atayde AR, Casala C, Galván P, de Torres C, Mora J, Lavarino C - Mol. Cancer (2010)

Chemotherapy-induced expression of CHD5 in 12 high risk NB tumors. (A) CHD5 immunoreactivity pre- and post-chemotherapy (400x); (B) Kaplan-Meier analysis for OS was performed using the mean between pre-treatment and post-treatment gene expression levels as cut-off to divide tumors which reactivate CHD5 and tumors that maintain low expression levels; (C) CHD5 transcript levels quantified by qRT-PCR: CHD5 expression levels (Black) at diagnosis, (Grey) post-chemotherapy. Fetal brain CHD5 expression represents normal neural tissue values.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2992029&req=5

Figure 4: Chemotherapy-induced expression of CHD5 in 12 high risk NB tumors. (A) CHD5 immunoreactivity pre- and post-chemotherapy (400x); (B) Kaplan-Meier analysis for OS was performed using the mean between pre-treatment and post-treatment gene expression levels as cut-off to divide tumors which reactivate CHD5 and tumors that maintain low expression levels; (C) CHD5 transcript levels quantified by qRT-PCR: CHD5 expression levels (Black) at diagnosis, (Grey) post-chemotherapy. Fetal brain CHD5 expression represents normal neural tissue values.
Mentions: Tumor histology and gene expression can change with treatment as a result of important changes in cellular processes. We investigated the effects of induction chemotherapy (3 cycles) on CHD5 expression in 12 high risk NB cases with available paired diagnostic and post-chemotherapy tumor specimens for qRT-PCR and immunohistochemical analyses. At diagnosis all these tumors (2 locoregional and 10 stage 4 NB) displayed low CHD5 mRNA expression and negative immunostaining. Following induction chemotherapy, a significant increase of CHD5 transcript and CHD5 positive nuclear staining was detected in 6/12 specimens, together with therapy-induced morphological changes (increased cytoplasm and ganglion-like cell morphology) (Figure 4A and 4C; cases #1-6). All these patients achieved an initial complete or very good response to cytotoxic therapy (chemo- and radiation therapy). At the time of analysis, 5/6 patients were alive with a mean follow-up of 35.62 months (Figure 4B). One case, stage 4 MYCN amplified, progressed after a good initial response to chemotherapy and died of refractory bone marrow disease (Figure 4C; case #6). Bone marrow aspirate smears of this patient exhibited widespread tumor dissemination with CHD5 negative neuroblast aggregates (data not shown).

Bottom Line: Within NTs, CHD5 immunoreactivity was found restricted to differentiating neuroblasts and ganglion-like cells, and absent in undifferentiated neuroblasts and stromal Schwann cells.Correlation between protein and mRNA levels was found, suggesting transcriptional regulation of CHD5.Re-establishment of CHD5 expression induced by chemotherapy could be a surrogate marker of treatment response.

View Article: PubMed Central - HTML - PubMed

Affiliation: Developmental Tumor Biology Laboratory, Hospital Sant Joan de Déu, Fundación Sant Joan de Déu, Barcelona, Spain.

ABSTRACT

Background: The chromodomain, helicase DNA-binding protein 5 (CHD5) is a potential tumor suppressor gene located on chromosome 1p36, a region recurrently deleted in high risk neuroblastoma (NB). Previous data have shown that CHD5 mRNA is present in normal neural tissues and in low risk NB, nevertheless, the distribution of CHD5 protein has not been explored. The aim of this study was to investigate CHD5 protein expression as an immunohistochemical marker of outcome in NB. With this purpose, CHD5 protein expression was analyzed in normal neural tissues and neuroblastic tumors (NTs). CHD5 gene and protein expression was reexamined after induction chemotherapy in a subset of high risk tumors to identify potential changes reflecting tumor response.

Results: We provide evidence that CHD5 is a neuron-specific protein, absent in glial cells, with diverse expression amongst neuron types. Within NTs, CHD5 immunoreactivity was found restricted to differentiating neuroblasts and ganglion-like cells, and absent in undifferentiated neuroblasts and stromal Schwann cells. Correlation between protein and mRNA levels was found, suggesting transcriptional regulation of CHD5. An immunohistochemical analysis of 90 primary NTs highlighted a strong association of CHD5 expression with favorable prognostic variables (age at diagnosis <12 months, low clinical stage, and favorable histology; P < 0.001 for all), overall survival (OS) (P < 0.001) and event-free survival (EFS) (P < 0.001). Multivariate analysis showed that CHD5 prognostic value is independent of other clinical and biologically relevant parameters, and could therefore represent a marker of outcome in NB that can be tested by conventional immunohistochemistry. The prognostic value of CHD5 was confirmed in an independent, blinded set of 32 NB tumors (P < 0.001).Reactivation of CHD5 expression after induction chemotherapy was observed mainly in those high risk tumors with induced tumor cell differentiation features. Remarkably, these NB tumors showed good clinical response and prolonged patient survival.

Conclusions: The neuron-specific protein CHD5 may represent a marker of outcome in NB that can be tested by conventional immunohistochemistry. Re-establishment of CHD5 expression induced by chemotherapy could be a surrogate marker of treatment response.

Show MeSH
Related in: MedlinePlus