Anti-gene peptide nucleic acid specifically inhibits MYCN expression in human neuroblastoma cells leading to cell growth inhibition and apoptosis

The MYCN oncogene and differentiation in neuroblastoma

Childhood neuroblastoma exhibits a heterogeneous clinical behavior ranging from low-risk tumors with the ability to spontaneously differentiate and regress, to high-risk tumors causing the highest number of cancer related deaths in infants. Amplification of the MYCN oncogene is one of the few prediction markers for adverse outcome. This gene encodes the MYCN transcriptional regulator predominantly expressed in the developing peripheral neural crest. MYCN is vital for proliferation, migration and stem cell homeostasis while decreased levels are associated with terminal neuronal differentiation. Interestingly, high-risk tumors without MYCN amplification frequently display increased c-MYC expression and/or activation of MYC signaling pathways. On the other hand, downregulation of MYCN leads to decreased proliferation and differentiation, emphasizing the importance of MYC signaling in neuroblastoma biology. Furthermore, expression of the neurotrophin receptor TrkA is associated with good prognosis, the ability to differentiate and spontaneous regression while expression of the related TrkB receptor is correlated with bad prognosis and MYCN amplification. Here we discuss the role of MYCN in neuroblastoma with a special focus on the contribution of elevated MYCN signaling for an aggressive and undifferentiated phenotype as well as the potential of using MYCN as a therapeutic target.

MicroRNA and DNA methylation alterations mediating retinoic acid induced neuroblastoma cell differentiation

Many neuroblastoma cell lines can be induced to differentiate into a mature neuronal cell type with retinoic acid and other compounds, providing an important model system for elucidating signalling pathways involved in this highly complex process. Recently, it has become apparent that miRNAs, which act as regulators of gene expression at a post-transcriptional level, are differentially expressed in differentiating cells and play important roles governing many aspects of this process. This includes the down-regulation of DNA methyltransferases that cause the de-methylation and transcriptional activation of numerous protein coding gene sequences. The purpose of this article is to review involvement of miRNAs and DNA methylation alterations in the process of neuroblastoma cell differentiation. A thorough understanding of miRNA and genetic pathways regulating neuroblastoma cell differentiation potentially could lead to targeted therapies for this disease.

Stable knockdown of MYCN by lentivirus-based RNAi inhibits human neuroblastoma cells growth in vitro and in vivo

Neuroblastoma is the most common childhood solid tumor, yet current treatment approaches have not been able to effectively control this cancer. Amplification and overexpression of MYCN have been shown to be closely related with high risk and poor prognosis in neuroblastoma. This suggests that MYCN is an important target for the antitumor therapy. Recently, vector-based RNA interference (RNAi) systems have been successfully used to eliminate gene expression, but knockdown of MYCN by vector-based RNAi as a therapeutic model for neuroblastoma has not been fully established. In this study, we used a lentivirus vector-based RNAi approach which expresses short hairpin RNA (shRNA) to knockdown MYCN in neuroblastoma cell lines IMR-32 and LAN-1. Western blotting analysis showed that expressions of MYCN were efficiently downregulated after infection with MYCN shRNA expression vector. The stable suppression of MYCN expression induced differentiation and apoptosis in neuroblastoma cell lines. Furthermore, we demonstrated that these changes were associated with caspase-3 activation, p27 upregulation as well as Bcl-2 and MDM2 downregulation. Finally, we demonstrated that downregulation of MYCN expression significantly reduced colony formation in vitro and tumor growth in nude mice. Our data indicate that lentivirus vector-mediated silencing of MYCN in neuroblastoma cells could efficiently and significantly inhibit tumor growth both in vitro and in vivo. Therefore we demonstrate the therapeutic potential of lentivirus-delivered shRNA as a novel approach for treatment of neuroblastoma and other malignant tumors with MYCN overexpression.

PNA-based artificial nucleases as antisense and anti-miRNA oligonucleotide agents

Because of its interesting chemical, physical and biological properties, Peptide Nucleic Acid (PNA) has attracted major attention in molecular biology, for diagnostics purposes and development of biosensors. PNAs have become candidates for gene therapeutic drugs in ANTISENSE (AO) strategy with favorable in vivo biochemical properties. Recently, antisense PNA oligonucleotides have been described in anti-miRNA approach (AMO). We propose PNA-based nucleases as AO and AMO agents. We report the design, synthesis and characterization of two kinds of artificial nucleases composed of a PEG-PNA-PEG domain conjugated to HGG·Cu (A) and DETA (B) as well known cleavage sites. Qualitative (MALDI-TOF) and quantitative (HTS) assays were planned to study nuclease activity of constructs A and B on RNA-3'-FAM target sequence. The results have highlighted the best performance of nuclease B and the relevance of the PEG spacer, in particular for conjugate A, in terms of efficiency of the cleavage, suggesting that conjugates A and B also act as potential antisense and anti-miRNA agents.

Microgravity assay of neuroblastoma: in vitro aggregation kinetics and organoid morphology correlate with MYCN expression

Neuroblastoma, the most common and deadly solid pediatric tumor, features genetic and biologic heterogeneity that defies simple risk assessments, drives diverse clinical behavior, and demands more extensive characterization. This research served to investigate the utility of a microgravity assay-rotary bioreactor culture-to evaluate and characterize the cell-specific, in vitro behavior of neuroblastoma cell lines: aggregation kinetics of single cells and the morphology of the formed structures, called organoids. Specifically, we examined the effect of amplification of the oncogene MYCN, a genetic factor that is strongly associated with poor clinical outcome. Three human neuroblastoma cell lines with varied MYCN expression (CHP-212 (unamplified), SK-N-AS (unamplified), IMR-32 (amplified)) were cultured in the microgravity rotary bioreactor. Simple aggregation kinetics were determined by periodically performing counts of non-aggregated single cells in the media. Organoids were harvested, stained with hematoxylin and eosin, and evaluated microscopically in terms of size and shape. The MYCN-amplified cell line (IMR32) aggregated much more rapidly than the unamplified cell lines, as indicated by a significantly lower area under its aggregation curve (single non-aggregated cells vs. time): IMR32=4.3, CHP-212 =12.4, SK-N-AS=9.8 (adhesion index ×10(5)). Further, the organoid morphology of the MYCN-amplified cell line was noticeably different compared to the unamplified lines. The CHP-212 and SK-N-AS cells formed spherical structures with average cross-sectional area 0.213 and 0.138 mm(2), respectively, and featured an outer viable zone of cells (average length of 0.175, 0.129 mm, respectively; the "diffusion distance"), surrounding an inner necrotic core. In contrast, the MYCN-amplified cell line formed a large single mass of cells but had a similar diffusion distance (0.175 mm). This microgravity assay provides a rapid, reproducible assessment of in vitro behavior of neuroblastoma, and the measured parameters, aggregation kinetics and organoid size and shape correlated with malignant potential in terms of MYCN amplification. This assay allows for the examination of cell-specific biologic and genetic factors that should provide valuable insight into the clinical behavior of neuroblastoma.

Conditional expression of retrovirally delivered anti-MYCN shRNA as an in vitro model system to study neuronal differentiation in MYCN-amplified neuroblastoma

Background

Neuroblastoma is a childhood cancer derived from immature cells of the sympathetic nervous system. The disease is clinically heterogeneous, ranging from neuronal differentiated benign ganglioneuromas to aggressive metastatic tumours with poor prognosis. Amplification of the MYCN oncogene is a well established poor prognostic factor found in up to 40% of high risk neuroblastomas.

Using neuroblastoma cell lines to study neuronal differentiation in vitro is now well established. Several protocols, including exposure to various agents and growth factors, will differentiate neuroblastoma cell lines into neuron-like cells. These cells are characterized by a neuronal morphology with long extensively branched neurites and expression of several neurospecific markers.

Results

In this study we use retrovirally delivered inducible short-hairpin RNA (shRNA) modules to knock down MYCN expression in MYCN-amplified (MNA) neuroblastoma cell lines. By addition of the inducer doxycycline, we show that the Kelly and SK-N-BE(2) neuroblastoma cell lines efficiently differentiate into neuron-like cells with an extensive network of neurites. These cells are further characterized by increased expression of the neuronal differentiation markers NFL and GAP43. In addition, we show that induced expression of retrovirally delivered anti-MYCN shRNA inhibits cell proliferation by increasing the fraction of MNA neuroblastoma cells in the G1 phase of the cell cycle and that the clonogenic growth potential of these cells was also dramatically reduced.

Conclusion

We have developed an efficient MYCN-knockdown in vitro model system to study neuronal differentiation in MNA neuroblastomas.

Biological effects of induced MYCN hyper-expression in MYCN-amplified neuroblastomas

Neuroblastoma is a childhood malignancy of the sympathetic nervous system. The tumor exhibits two different phenotypes: favorable and unfavorable. MYCN amplification is associated with rapid tumor progression and the worst neuroblastoma disease outcome. We have previously reported that inhibitors of histone deacetylase (HDAC) and proteasome enhance favorable neuroblastoma gene expression in neuroblastoma cell lines and inhibit growth of these cells. In this study, we investigated the effect of trichostatin A or TSA (an HDAC inhibitor), and epoxomycin (a proteasome inhibitor) on MYCN and p53 expression in MYCN-amplified neuroblastoma cells. It was found that TSA down-regulated MYCN expression, but Epoxomycin and the TSA/Epoxomycin combination led to MYCN hyper-expression in MYCN-amplified neuroblastoma cell lines. Despite their contrasting effects on MYCN expression, TSA and Epoxomycin caused growth suppression and cell death of the MYCN-amplified cell lines examined. Consistent with these data, forced hyper-expression of MYCN in MYCN-amplified IMR5 cells via transfection resulted in growth suppression and the increased expression of several genes known to suppress growth or induce cell death. Furthermore, Epoxomycin as a single agent and its combination with TSA enhance p53 expression in the MYCN-amplified neuroblastoma cell lines. Unexpectedly, co-transfection of TP53 and MYCN in IMR5 cells resulted in high p53 expression but a reduction of MYCN expression. Together our data suggest that either down regulation or hyper-expression of MYCN results in growth inhibition and/or apoptosis of MYCN-amplified neuroblastoma cells. In addition, elevated p53 expression has a suppressive effect on MYCN expression in these cells.

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

BACKGROUND

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.

RESULTS

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.

CONCLUSIONS

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.

MYC in oncogenesis and as a target for cancer therapies

MYC proteins (c-MYC, MYCN, and MYCL) regulate processes involved in many if not all aspects of cell fate. Therefore, it is not surprising that the MYC genes are deregulated in several human neoplasias as a result from genetic and epigenetic alterations. The near "omnipotency" together with the many levels of regulation makes MYC an attractive target for tumor intervention therapy. Here, we summarize some of the current understanding of MYC function and provide an overview of different cancer forms with MYC deregulation. We also describe available treatments and highlight novel approaches in the pursuit for MYC-targeting therapies. These efforts, at different stages of development, constitute a promising platform for novel, more specific treatments with fewer side effects. If successful a MYC-targeting therapy has the potential for tailored treatment of a large number of different tumors.

MYCN oncoprotein targets and their therapeutic potential

The MYCN oncogene encodes a transcription factor which is amplified in up to 40% of high risk neuroblastomas. MYCN amplification is a well-established poor prognostic marker in neuroblastoma, however the role of MYCN expression and the mechanisms by which it acts to promote an aggressive phenotype remain largely unknown. This review discusses the current evidence identifying the direct and indirect downstream transcriptional targets of MYCN from recent studies, with particular reference to how MYCN affects the cell cycle, DNA damage response, differentiation and apoptosis in neuroblastoma.

Frontiers in the management of retinoblastoma

PURPOSE

To provide an overview of the current clinical management of retinoblastoma by discussing the trends in the categorization, treatment, and recent advances in molecular diagnostics as well as therapy for retinoblastoma.

DESIGN

Literature review and commentary.

METHODS

Selected articles from the medical literature and the authors' clinical and research experience were reviewed critically.

RESULTS

Retinoblastoma has evolved from a deadly childhood cancer to a largely curable cancer within the past 40 years. Current treatment strategies aim to salvage the eye and provide the best visual outcome possible. Using the international classification system to stratify intraocular retinoblastoma into treatment groups, the multicenter Children's Oncology Group treatment protocols use 2- to 3-drug chemoreduction with focal consolidative therapy for most categories of disease. Furthermore, collaborative efforts are being directed toward a better understanding of genotype-phenotype relationships in retinoblastoma that will be useful in the multidisciplinary management of this disease. Molecular targeting therapy is emerging as a potential strategy to individualize therapy. Finally, improvements in local drug delivery methods and vehicles are providing solutions for the problem of systemic toxicity from existing chemotherapy regimens.

CONCLUSIONS

The management of retinoblastoma has become a prototype for other ophthalmic diseases and systemic cancers in which genetic information and molecular targets are being used to design more elegant treatment strategies.

Synthesis, characterization, and evaluation of a novel 99mTc(CO)3 pyrazolyl conjugate of a peptide nucleic acid sequence

The 16-mer peptide nucleic acid sequence H-A GAT CAT GCC CGG CAT-Lys-NH2 (1), which is complementary to the translation start region of the N-myc oncogene messenger RNA, was synthesized and conjugated to a pyrazolyl diamine bifunctional chelator (pz). The novel conjugate pz-A GAT CAT GCC CGG CAT-Lys-NH2 (2) was labeled with technetium tricarbonyl, yielding quantitatively the complex fac-[99mTc(CO)3(kappa3-pz-A GAT CAT GCC CGG CAT-Lys-NH2)]2+ (4). Complex 4 was obtained with high radiochemical purity and high specific activity, revealing high stability in human serum and in cell culture medium. The identity of 4 was confirmed by comparing its reversed-phase high performance liquid chromatography profile with that of the rhenium analog fac-[Re(CO)3(kappa3-pz-A GAT CAT GCC CGG CAT-Lys-NH2)]2+ (3), prepared by conjugation of fac-[Re(CO)3(3,5-Me2pz(CH2)2N((CH2)3COOH)(CH2)2NH2)]+ to 1, using solid-phase techniques. UV melting experiments of 1 and 3 with the complementary DNA sequence led to the formation of stable duplexes, indicating that the conjugation of 1 to the pyrazolyl chelator and to the metal fragment fac-[M(CO)3]+ did not affect the recognition of the complementary sequence as well as the duplex stability. For a first screening, SH-SY5Y human neuroblastoma cells, which express N-myc, were treated with 4. The results show that 4 internalizes (7% of the activity goes into the cells, after 4 h at 37 degrees C), presenting also a relatively high cellular retention (only 40% of internalized activity is released from the cells after 5 h).

Paracrine inhibition of osteoblast differentiation induced by neuroblastoma cells

The aim of our study was to investigate whether the defective function of osteogenic cells induced by neuroblastoma might play a role in the development of skeletal metastases. This mechanism has been extensively demonstrated for multiple myeloma, in which the blockage of osteoblast differentiation has been ascribed to the inhibitors of canonical Wingless pathway (Wnt), namely Dickkopf 1 (Dkk1). Our purpose was to verify if neuroblastoma cells derived from bone marrow metastases (SH-SY5Y, LAN1) or primaries (NB100, CHP212) hamper the differentiation of mesenchymal stem cells (hMSCs) into osteoblasts in a paracrine manner, and to test whether this ability depends on Dkk1 activity. We found that all neuroblastoma cells increased the proliferation of hMSCs collected from pediatric-aged donors, with a corresponding decrease in osteoblast differentiation markers, including alkaline phosphatase (ALP), analyzed as gene expression, enzymatic activity and number of ALP-positive colony forming units, osteoprotegerin (OPG) release, OPG and osteocalcin gene-expression. Dkk1 mRNA and protein were detectable in all cell lines, and the use of neutralizing anti-Dkk1 antibody reversed the effects induced by SH-SY5Y cells. Taken together, our results confirm that neuroblastoma hinders osteoblastogenesis, and that Dkk1 release seems to play a crucial role in blocking the differentiation of osteoprogenitor cells, though the ability to promote osteoclast activation remains an essential requirement for the development of skeletal metastases. Finally, our findings suggest that strategies regulating Wnt signaling and Dkk1 activity could be considered for adjuvant therapies in neuroblastoma metastasizing to the skeleton.

Binomial mitotic segregation of MYCN-carrying double minutes in neuroblastoma illustrates the role of randomness in oncogene amplification

BACKGROUND

Amplification of the oncogene MYCN in double minutes (DMs) is a common finding in neuroblastoma (NB). Because DMs lack centromeric sequences it has been unclear how NB cells retain and amplify extrachromosomal MYCN copies during tumour development.

PRINCIPAL FINDINGS

We show that MYCN-carrying DMs in NB cells translocate from the nuclear interior to the periphery of the condensing chromatin at transition from interphase to prophase and are preferentially located adjacent to the telomere repeat sequences of the chromosomes throughout cell division. However, DM segregation was not affected by disruption of the telosome nucleoprotein complex and DMs readily migrated from human to murine chromatin in human/mouse cell hybrids, indicating that they do not bind to specific positional elements in human chromosomes. Scoring DM copy-numbers in ana/telophase cells revealed that DM segregation could be closely approximated by a binomial random distribution. Colony-forming assay demonstrated a strong growth-advantage for NB cells with high DM (MYCN) copy-numbers, compared to NB cells with lower copy-numbers. In fact, the overall distribution of DMs in growing NB cell populations could be readily reproduced by a mathematical model assuming binomial segregation at cell division combined with a proliferative advantage for cells with high DM copy-numbers.

CONCLUSION

Binomial segregation at cell division explains the high degree of MYCN copy-number variability in NB. Our findings also provide a proof-of-principle for oncogene amplification through creation of genetic diversity by random events followed by Darwinian selection.

Natural jasmonates of different structures suppress the growth of human neuroblastoma cell line SH-SY5Y and its mechanisms

AIM

Recent evidence has indicated that members of natural jasmonates, a family of plant stress hormones, exhibit anticancer activity. The current study was undertaken to investigate the effects of jasmonates on the in vitro growth of human neuroblastomas, one of the most common solid tumors in children.

METHODS

Cellular proliferation was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide colorimetry and colony formation assay. Apoptosis was detected by Hoechst 33258 staining and flow cytometry. Western blotting was applied to assay gene expression.

RESULTS

The administration of natural jasmonates, methyl jasmonate, cis-jasmone, and jasmonic acid to cultured neuroblastoma cell line SH-SY5Y, resulted in a decrease of cell proliferation in a doseand time-dependent manner. However, the in vitro growth of cultured human embryonic kidney (HEK) cell line HEK 293 was not affected by jasmonates. The cell cycles of jasmonate-treated SH-SY5Y cells were arrested at the G2/M phase. The incubation of SH-SY5Y cells with jasmonates resulted in characteristic changes of apoptosis. The anticancer activities of natural jasmonates on SH-SY5Y cells are as follows: methyl jasmonate>cis-jasmone>jasmonic acid. In addition, the expressions of proliferating cell nuclear antigen and N-myc were downregulated by methyl jasmonate. Moreover, methyl jasmonate decreased the expression of the Xlinked inhibitor of apoptosis protein and survivin, critical members of inhibitors of the apoptosis protein family, in SH-SY5Y cells.

CONCLUSION

Jasmonates suppress the growth of human neuroblastoma cell line SH-SY5Y via inhibiting cell proliferation and inducing apoptosis, which lays the groundwork for further investigation into the anticancer activities and its mechanisms of natural jasmonates on human neuroblastomas.

Circular dichroism study of DNA binding by a potential anticancer peptide nucleic acid targeted against the MYCN oncogene

The interaction with DNA of a peptide nucleic acid (PNA) oligomer (16nt) conjugated with a nuclear localization signal (NLS) peptide, which was previously found to be able to inhibit tumor cell proliferation through block of transcription of the MYCN oncogene, was studied by UV and CD spectroscopy. While data obtained by UV were not conclusive, the use of circular dichroism gave clear-cut evidence of the formation of a PNA:DNA duplex of exceptionally high stability (Tm >or= 90 degrees C). Using the same approach, the effect of mutations on DNA:PNA stability was evaluated, and was found in accordance with that expected for a Watson-Crick interaction. The role of the NLS peptide was evaluated by using a PNA lacking of this part, which gave rise to less stable PNA:DNA duplexes. Finally, a competition experiment carried out with a 26mer dsDNA, containing the target 16mer sequence in its middle region, in the presence of PNA-NLS gave evidence for the formation of a ternary complex at 25 degrees , while at higher temperature, the PNA:DNA duplex and the displaced homologous DNA strand were detected. The present results support the possibility of an analogous mechanism of action of this antitumor PNA in vivo.

Chirality as a tool in nucleic acid recognition: principles and relevance in biotechnology and in medicinal chemistry

The understanding of the interaction of chiral species with DNA or RNA is very important for the development of new tools in biology and of new drugs. Several cases in which chirality is a crucial point in determining the DNA binding mode are reviewed and discussed, with the aim of illustrating how chirality can be considered as a tool for improving the understanding of mechanisms and the effectiveness of nucleic acid recognition. The review is divided into two parts: the former describes examples of chiral species interacting with DNA: intercalators, metal complexes, and groove binders; the latter part is dedicated to chirality in DNA analogs, with discussion of phosphate stereochemistry and chirality of ribose substitutes, in particular of peptide nucleic acids (PNAs) for which a number of works have been published recently dealing with the effect of chirality in DNA recognition. The discussion is intended to show how enantiomeric recognition originates at the molecular level, by exploiting the enormous progresses recently achieved in the field of structural characterization of complexes formed by nucleic acid with their ligands by crystallographic and spectroscopic methods. Examples of application of the DNA binding molecules described and the role of chirality in DNA recognition relevant for biotechnology or medicinal chemistry are reported.

MYCN silencing induces differentiation and apoptosis in human neuroblastoma cells

MYCN amplification strongly correlates with unfavorable outcomes in patients with neuroblastoma. The aim of this study was to investigate the role of MYCN in neuroblastoma cell differentiation and apoptosis. We used the technique of RNA interference to inhibit MYCN gene expression in neuroblastoma cells with variable expression of MYCN. Our results showed that inhibition of MYCN gene expression in MYCN amplified cells induced apoptosis and suppressed cell growth; neuronal differentiation also occurred after MYCN gene silencing. Moreover, N-myc downregulation was associated with decreased Bcl-xL protein levels and caspase-3 activation. These data show that small interfering RNA directed to MYCN, which plays a crucial role in neuroblastoma cell survival, may provide a potential novel therapeutic option for aggressive neuroblastomas.

The Myc oncoprotein as a therapeutic target for human cancer

Myc expression is deregulated in a wide range of human cancers and is often associated with aggressive, poorly differentiated tumors. The Myc protein is a transcription factor that regulates a variety of cellular processes including cell growth and proliferation, cell-cycle progression, transcription, differentiation, apoptosis, and cell motility. Potential strategies that either inhibit the growth promoting effect of Myc and/or activate its pro-apoptotic function are presently being explored. In this review, we give an overview of Myc activation in human tumors and discuss current strategies aimed at targeting Myc for cancer treatment. Such therapies could have potential in combination with mechanistically different cytotoxic drugs to combat and eradicate tumors cells.

MYCN deregulation as a potential target for novel therapies in rhabdomyosarcoma

Rhabdomyosarcoma is the most common soft-tissue sarcoma of childhood. Treatment requires a multimodality approach combining chemotherapy with surgery and radiotherapy. Although overall outcomes have improved considerably, the outlook for patients with high-risk disease, particularly the alveolar subtype, remains bleak and there is a clear need for new chemotherapeutic strategies. This review focuses on the possibilities for interventions targeting myc myelocytomatosis viral related oncogene, neuroblastoma derived (MYCN). The importance of aberrant expression of this oncogene is well established in neuroblastoma and recent data indicate that MYCN deregulation also occurs in up to a quarter of alveolar subtype cases. A range of possible approaches to target MYCN is discussed, including nucleic acid-based and immunotherapy strategies.