960

CD44

CDW44|CSPG8|ECMR-III|HCELL|HUTCH-I|IN|LHR|MC56|MDU2|MDU3|MIC4|Pgp1;CD44 molecule (Indian blood group);CD44;CD44 molecule (Indian blood group)

CD44 antigen|GP90 lymphocyte homing/adhesion receptor|Hermes antigen|cell surface glycoprotein CD44|chondroitin sulfate proteoglycan 8|epican|extracellular matrix receptor III|hematopoietic cell E- and L-selectin ligand|heparan sulfate proteoglycan|homing

11p13

protein-coding

The BRAF gene has been shown to be a major target for mutations in papillary thyroid carcinoma (PTC) (36-69%), which forms almost ALL of the over 2000 cases of thyroid carcinoma that have occurred in Chernobyl. BRAF is activated by pointmutation, and were it to occur at a high frequency in Chernobyl-related tumors, it would challenge the dominant role of double-strand breaks in radiation-induced PTC. In a previous study, we detected the BRAF V600E mutation in 46% (23 of 50) of sporadic adult PTC. Using the same methodology, we have analyzed 34 post-Chernobyl PTC and detected RET/PTC rearrangements in 14 (41%) and BRAF mutations (V600E) in four (12%). These two alterations did not coexist in any PTCs. The mean age at exposure of patients with PTC showing BRAF mutation was higher than that of patients with tumors without BRAF mutation irrespective of their RET status. We have also analyzed 17 sporadic cases of childhood PTC and found that only one (6%) harbored the BRAF V600E mutation. We conclude that the frequency of BRAF mutations is significantly lower (P = 0.0008) in post-Chernobyl PTC than in adult sporadic PTC, whereas no significant difference was found between post-Chernobyl and sporadic childhood PTCs.

PURPOSE: Neuroblastoma is a childhood cancer that exhibits either a favorable oran unfavorable phenotype. Favorable neuroblastoma genes (EPHB6, EFNB2, EFNB3, NTRK1, and CD44) are genes whose high-level expression predicts favorable neuroblastoma disease outcome. Accordingly, the forced expression of these genesor their reactivation by gene silencing inhibitors in unfavorable neuroblastoma cells results in suppression of tumor growth and metastases. This study was undertaken to design an experimental strategy to identify additional favorable neuroblastoma genes. EXPERIMENTAL DESIGN: Favorable neuroblastoma gene candidates were first identified by gene expression profiling analysis on IMR5 neuroblastoma cells treated with inhibitors of DNA methylation and histone deacetylase againstthe untreated control cells. Among the candidates, we focused on MIZ-1, which encodes a MYC-interacting zinc-finger protein, because it is known to enhance the expression of growth suppressive genes, such as CDKN1A. RESULTS: High-level MIZ-1 expression was associated with favorable disease outcome of neuroblastoma (P = 0.0048). Forced MIZ-1 expression suppressed in vitro growth of neuroblastoma cell lines. High MIZ-1 expression was correlated with the small-size neuroblastoma xenografts treated with gene silencing inhibitors or a glucocorticoid. In addition, forced MIZ-1 expression enhanced the expression of CD44 and EFNB2 in neuroblastoma cell lines in vitro. Furthermore, MIZ-1 expression was positively correlated with the expression of favorable neuroblastoma genes (EFNB2, EFNB3, EPHB6, and NTRK1) in the human neuroblastoma xenograft therapeutic models. CONCLUSION: MIZ-1 is a new favorable neuroblastoma gene, which may directly or indirectly regulate the expression of other favorable neuroblastoma genes.

Comparisons of the developing human sympathetic nervous system (SNS) to tumors presumed to derive from these cells may suggest tumor progenitors and predict tumor biologic behavior. Classic neuroblastoma (NB) and its more highly differentiated stroma-rich subtypes, extra-adrenal sympathetic paraganglioma, and pheochromocytoma were examined for the presence of the developmentally characterized gene products NSE, S-100, CD44, Bcl-2, HNK-1, PNMT, TrkA, IGF2, and tyrosine hydroxylase. The marker gene expression profiles of these tumors were compared with those similarly determined for a number of normal prenatal and postnatal human SNS cell types. Sympathetic paraganglioma, pheochromocytoma, andstroma-rich NB display marker expression profiles mimicking those of childhood sympathetic paraganglia, adrenal chromaffin cells, and sympathetic neurons, respectively. A selection of differentiating, extra-adrenal NB tumors with prognostically favorable features possess marker gene expression profiles paralleling that observed for fetal extra-adrenal sympathetic paraganglia/small intensely fluorescent cells. In contrast, undifferentiated, clinically aggressive NB tumors manifest characteristics mirroring that of embryonic/early fetal sympathetic neuroblasts of sympathetic ganglia and of the adrenal gland. These findings suggest that clinical features, such as primary tumor location and age at diagnosis, provide prognostic information for NB patients by virtue of the existence and biology of the presumed tumor progenitor cell type.

Disseminated neuroblastoma frequently show a very poor prognosis. N-myc gene amplification, 1p deletion and lack of CD44 gene expression, are ALL genetic factors associated with the disease's dissemination. Human neuroblastoma xenografts in nude mice has permitted to characterize, in disseminated neuroblasts, oncogenes overexpression, inactivation of tumor suppressor genes aswell as detoxifying genes activation which contributes to increase cellular resistance to chemotherapy. These genetic abnormalities permit to propose a nosology of this very aggressive pediatric solid tumor. Hopefully, this genetic classification could be of great value for new therapeutic approaches.