3880

KRT19

CK19|K19|K1CS;keratin 19;KRT19;keratin 19

40-kDa keratin intermediate filament|CK-19|cytokeratin 19|cytokeratin-19|keratin, type I cytoskeletal 19|keratin, type I, 40-kd|keratin-19

17q21.2

protein-coding

BACKGROUND: Epigenetic mechanisms such as DNA methylation and histone modifications are important regulators of gene expression and are frequently involved in silencing tumor suppressor genes. METHODS: In order to identify genes that are epigenetically regulated in neuroblastoma tumors, we treated four neuroblastoma cell lines with the demethylating agent 5-Aza-2'-deoxycytidine (5-Aza-dC) either separately or in conjunction with the histone deacetylase inhibitor trichostatin A (TSA). expression was analyzed using whole-genome expression arrays to identify genes activated by the treatment. These data were then combined with data from genome-wide DNA methylation arrays to identify candidate genes silenced in neuroblastoma due to DNA methylation. RESULTS: We present eight genes (KRT19, PRKCDBP, SCNN1A, POU2F2, TGFBI, COL1A2, DHRS3 and DUSP23) that are methylated in neuroblastoma, most of them not previously reported as such, some of which also distinguish between biological subsets of neuroblastoma tumors. Differential methylation was observed for the genes SCNN1A(p < 0.001), PRKCDBP (p < 0.001) and KRT19 (p < 0.01). Among these, the mRNA expression of KRT19 and PRKCDBP was significantly lower in patients that have died from the disease compared with patients with no evidence of disease (fold change -8.3, p = 0.01 for KRT19 and fold change -2.4, p = 0.04 for PRKCDBP). CONCLUSIONS: In our study, a low methylation frequency of SCNN1A, PRKCDBP and KRT19 is significantly associated with favorable outcome in neuroblastoma. It islikely that analysis of specific DNA methylation will be one of several methods in future patient therapy stratification protocols for treatment of childhood neuroblastomas.

MicroRNAs (miRNAs) are well-known regulators of proliferation, apoptosis, and differentiation and are recognized to play an important role in the development of cancers. Here we aimed to identify the functional contribution of miRNAs to the biology of hepatoblastoma (HB), the most common malignant liver tumor in childhood. As overexpression of the oncogene PLAG1 (pleomorphic adenoma gene 1) is a characteristic phenomenon in HB, we used RNA interference and subsequent miRNA array analysis to identify miR-492 as most strongly influenced by PLAG1. We provide novel experimental evidence that miR-492 can originate from the coding sequence of the HB marker gene keratin 19 (KRT19). In agreement with these in vitro observations, significantly elevated levels of coexpressed KRT19 and miR-492 were particularly found in metastatic HB tumor samples. Stable overexpression of miR-492 in HB cell clones served to identify a broad range of differentially expressed transcripts, including several candidate targets of miR-492 predicted by computational algorithms. Among those the liver enzyme BAATshowed significant association with miR-492 expression in HB tumor samples. CONCLUSION: A close functional relationship between KRT19 and miR-492 was identified that may play an important role in the progression of malignant embryonal liver tumors. Additionally, miR-492 and its associated targets might serve as new HB biomarkers of clinical utility and could assist to explore targeted therapies, especially in metastatic HB with a poor prognosis.#CI- Copyright (c) 2010 American Association for the Study of Liver diseases.