No abstract

KvDMR (an intronic CpG island within the KCNQ1 gene) is one of the imprinting control regions on human chromosome 11p15.5. Since KvDMR exists within the promoter region of KCNQ1OT1 (antisense transcript of KCNQ1), it is likely that genomic alterations of this region including deletion, paternal uniparental disomy and de-methylation in maternal allele lead to aberrant overexpression of KCNQ1OT1. Indeed, de-methylation of KvDMR accompanied by uncontrolled overexpression of KCNQ1OT1 occurs frequently in Beckwith-Wiedemann syndrome (BWS), and around 10% of BWS patients developed embryonal tumors (Wilms' tumor or hepatoblastoma). These observations strongly suggest that silencing of KCNQ1OT1 expression might suppress its oncogenic potential. In the present study, we designed two pyrrole-imidazole (PI) polyamides, termed PI-a and PI-b, which might have the ability to bind to CCAAT boxes of the KCNQ1OT1 promoter region, and investigated their possible antitumor effect on Wilms' tumor-derived G401 cells. Gel retardation assay demonstrated that PI-a and PI-b specifically bind to their target sequences. Microscopic observations showed the efficient nuclear access of these PI polyamides. Quantitative real-time PCR analysis revealed that the expression level of KCNQ1OT1 was significantly decreased when treated with PI-a and PI-b simultaneously but not with either PI-a or PI-b single treatment. Consistent with these results, the combination of PI-a and PI-b resulted in a significant reduction in viability of G401 cells in a dose-dependent manner. Furthermore, FACS analysis demonstrated that combinatory treatment with PI-a and PI-b induces cell death as compared with control cells. Taken together, our present observations strongly suggest that the combinatory treatment with PI polyamides targeting KCNQ1OT1 might be a novel therapeutic strategy to cure patients with tumors over-expressing KCNQ1OT1.

No abstract

We demonstrated that two tDMRs frequently displayed altered methylation patterns in the NB genome, suggesting their distinct involvement in NB development/differentiation. The combined analysis of these two regions could serve as a diagnostic biomarker for poor clinical outcome.

Abstract. Neuroblastoma is a childhood malignancy originating from the sympathetic nervous system and accounts for approximately 15% of all pediatric cancer-related deaths. To newly identify gene(s) implicated in the progression of neuroblastoma, we investigated aberrantly methylated genomic regions in mouse skin tumors. Previously, we reported that TFAP2E, a member of activator protein-2 transcription factor family, is highly methylated within its intron and its expression is strongly suppressed in mouse skin tumors compared with the normal skin. In the present study, we analyzed public data of neuroblastoma patients and found that lower expression levels of TFAP2E are significantly associated with a shorter survival. The data indicate that TFAP2E acts as a tumor suppressor of neuroblastoma. Consistent with this notion, TFAP2E-depleted neuroblastoma NB1 and NB9 cells displayed a substantial resistance to DNA damage arising from adriamycin (ADR), cisplatin (CDDP) and ionizing radiation (IR). Silencing of TFAP2E caused a reduced ADR-induced proteolytic cleavage of caspase-3 and PARP. Of note, compared with the untransfected control cells, ADR-mediated stimulation of CDK inhibitor p21 WAF1 was markedly upregulated in TFAP2E-knocked down cells. Therefore, our present findings strongly suggest that TFAP2E has a pivotal role in the regulation of DNA damage response in NB cells through the induction of p21