Inhibition of cyclin-dependent kinase 1-induced cell death in neuroblastoma cells through the microRNA-34a-MYCN-survivin pathway.

Neuroblastoma is the most common pediatric solid extracranial malignancy. Increased expression of MYCN, a member of Myc family, is associated with a poor prognosis in patients with neuroblastoma. Cyclin-dependent kinase 1 (CDK1) is known to be critical to the survival of Myc-overexpressing neoplasms. In this study, we investigated the effects of CDK1 inhibition on the viability of neuroblastoma cells and the underlying molecular mechanisms. We assessed the effects of CDK1 inhibitors on the viability of neuroblastoma cells and explored MYCN-associated mechanisms by using real-time reverse-transcription polymerase chain reaction, chromatin immunoprecipitation, and micro-RNA quantification. CDK1 inhibitors induced cytotoxicity and apoptosis and decreased expression of MYCN and survivin in neuroblastoma cells. Knockdown of MYCN mRNA expression caused significant cell death and transcomplementation of MYCN increased cell viability in neuroblastoma cells treated with CDK1 inhibitors. Furthermore, MYCN mRNA was inhibited by CDK1 inhibitor at the posttranscriptional level. The expression of survivin was also responsive to the change of MYCN levels, and according to the chromatin immunoprecipitation assay, MYCN bound the promoter region of the survivin gene. CDK1 inhibition caused elevation of microRNA-34a (miR-34a), and anti-miR-34a not only restored the expression of MYCN but also increased cell survival of neuroblastoma cells treated with CDK1 inhibitor. CDK1 inhibition-induced cell death was dependent, although not completely, on the decreased level of MYCN- and miR-34a-mediated, CDK1 inhibition-induced down-regulation of MYCN, which thereby decreased the transcriptional activation of MYCN on the survivin promoter. We propose that CDK1 inhibition-induced cell death of neuroblastoma cells occurs through the miR-34a-MYCN-survivin pathway.

Chen Y ，Tsai YH ，Tseng SH 《-》

Novel anthranilamide-pyrazolo[1,5-a]pyrimidine conjugates modulate the expression of p53-MYCN associated micro RNAs in neuroblastoma cells and cause cell cycle arrest and apoptosis.

It has previously been shown that anthranilamide-pyrazolo[1,5-a]pyrimidine conjugates activate p53 and cause apoptosis in cervical cancer cells such as HeLa and SiHa. Here we establish the role of these conjugates in activating p53 pathway by phosphorylation at Ser15, 20 and 46 residues and downregulate key oncogenic proteins such as MYCN and Mdm2 in IMR-32 neuroblastoma cells. Compounds decreased the proliferation rate of neuroblastoma cells such as IMR-32, Neuro-2a, SK-N-SH. Compound treatment resulted in G2/M cell cycle arrest. The expression of p53 dependent genes such as p21, Bax, caspases was increased with concomitant decrease of the survival proteins as well as anti-apoptotic proteins such as Akt1, E2F1 and Bcl2. In addition the expression of important microRNAs such as miR-34a, c, miR-200b, miR-107, miR-542-5p and miR-605 were significantly increased that eventually lead to the activation of apoptotic pathway. Our data revealed that conjugates of this nature cause cell cycle arrest and apoptosis in IMR-32 cells [MYCN (+) with intact wild-type p53] by activating p53 signalling and provides a lead for the development of anti-cancer therapeutics.

Ramaiah MJ ，Pushpavalli SN ，Lavanya A ，Bhadra K ，Haritha V ，Patel N ，Tamboli JR ，Kamal A ，Bhadra U ，Pal-Bhadra M ... -  《-》

Combined IFN-gamma and retinoic acid treatment targets the N-Myc/Max/Mad1 network resulting in repression of N-Myc target genes in MYCN-amplified neuroblastoma cells.

Cetinkaya C ，Hultquist A ，Su Y ，Wu S ，Bahram F ，Påhlman S ，Guzhova I ，Larsson LG ... -  《MOLECULAR CANCER THERAPEUTICS》

Inhibition of mir-21, which is up-regulated during MYCN knockdown-mediated differentiation, does not prevent differentiation of neuroblastoma cells.

Neuroblastoma is a malignant childhood tumour arising from precursor cells of the sympathetic nervous system. Genomic amplification of the MYCN oncogene is associated with dismal prognosis. For this group of high-risk tumours, the induction of tumour cell differentiation is part of current treatment protocols. MicroRNAs (miRNAs) are small non-coding RNA molecules that effectively reduce the translation of target mRNAs. MiRNAs play an important role in cell proliferation, apoptosis, differentiation and cancer. In this study, we investigated the role of N-myc on miRNA expression in MYCN-amplified neuroblastoma. We performed a miRNA profiling study on SK-N-BE (2) cells, and determined differentially expressed miRNAs during differentiation initiated by MYCN knockdown, using anti-MYCN short-hairpin RNA (shRNA) technology. Microarray analyses revealed 23 miRNAs differentially expressed during the MYCN knockdown-mediated neuronal differentiation of MNA neuroblastoma cells. The expression changes were bidirectional, with 11 and 12 miRNAs being up- and down-regulated, respectively. Among the down-regulated miRNAs, we found several members of the mir-17 family of miRNAs. Mir-21, an established oncomir in a variety of cancer types, became strongly up-regulated upon MYCN knockdown and the subsequent differentiation. Neither overexpression of mir-21 in the high-MYCN neuroblastoma cells, nor repression of increased mir-21 levels during MYCN knockdown-mediated differentiation had any significant effects on cell differentiation or proliferation. We describe a subset of miRNAs that were altered during the N-myc deprived differentiation of MYCN-amplified neuroblastoma cells. In this context, N-myc acts as both an activator and suppressor of miRNA expression. Mir-21 was up-regulated during cell differentiation, but inhibition of mir-21 did not prevent this process. We were unable to establish a role for this miRNA during differentiation and proliferation of the two neuroblastoma cell lines used in this study.

Buechner J ，Henriksen JR ，Haug BH ，Tømte E ，Flaegstad T ，Einvik C ... -  《-》

MYCN concurrence with SAHA-induced cell death in human neuroblastoma cells.

Cortés C ，Kozma SC ，Tauler A ，Ambrosio S ... -  《-》