Imprinted CDKN1C is a tumor suppressor in rhabdoid tumor and activated by restoration of SMARCB1 and histone deacetylase inhibitors

SMARCB1 Gene Therapy Using a Novel Tumor-Targeted Nanomedicine Enhances Anti-Cancer Efficacy in a Mouse Model of Atypical Teratoid Rhabdoid Tumors

Purpose

Atypical teratoid rhabdoid tumor (ATRT) is a deadly, fast-growing form of pediatric brain cancer with poor prognosis. Most ATRTs are associated with inactivation of SMARCB1, a subunit of the chromatin remodeling complex, which is involved in developmental processes. The recent identification of SMARCB1 as a tumor suppressor gene suggests that restoration of SMARCB1 could be an effective therapeutic approach.

Methods

We tested SMARCB1 gene therapy in SMARCB1-deficient rhabdoid tumor cells using a novel tumor-targeted nanomedicine (termed scL-SMARCB1) to deliver wild-type SMARCB1. Our nanomedicine is a systemically administered immuno-lipid nanoparticle that can actively cross the blood-brain barrier via transferrin receptor-mediated transcytosis and selectively target tumor cells via transferrin receptor-mediated endocytosis. We studied the antitumor activity of the scL-SMARCB1 nanocomplex either as a single agent or in combination with traditional treatment modalities in preclinical models of SMARCB1-deficient ATRT.

Results

Restoration of SMARCB1 expression by the scL-SMARCB1 nanocomplex blocked proliferation, and induced senescence and apoptosis in ATRT cells. Systemic administration of the scL-SMARCB1 nanocomplex demonstrated antitumor efficacy as monotherapy in mice bearing ATRT xenografts, where the expression of exogenous SMARCB1 modulates MYC-target genes. scL-SMARCB1 demonstrated even greater antitumor efficacy when combined with either cisplatin-based chemotherapy or radiation therapy, resulting in significantly improved survival of ATRT-bearing mice.

Conclusion

Collectively, our data suggest that restoring SMARCB1 function via the scL-SMARCB1 nanocomplex may lead to therapeutic benefits in ATRT patients when combined with traditional chemoradiation therapies.

STEAP3 promotes colon cancer cell proliferation and migration via regulating histone acetylation

Colorectal cancer (CRC) is the third most prevalent diagnosed cancer in men and second most prevalent cancer in women. H3K27ac alterations are more commonly than gene mutations in colorectal cancer. Most colorectal cancer genes have significant H3K27ac changes, which leads to an over-expression disorder in gene transcription. Over-expression of STEAP3 is involved in a variety of tumors, participating in the regulation of cancer cell proliferation and migration. The purpose of this work is to investigate the role of STEAP3 in the regulation of histone modification (H3K27ac) expression in colon cancer. Bioinformatic ChIP-seq, ChIP-qPCR and ATAC-seq were used to analyze the histone modification properties and gene accessibility of STEAP3. Western blot and qRT-PCR were used to evaluate relative protein and gene expression, respectively. CRISPR/Cas9 technology was used to knockout STEAP3 on colon cancer cells to analyze the effect of ATF3 on STEAP3. STEAP3 was over-expressed in colon cancer and associated with higher metastases and more invasive and worse stage of colon cancer. ChIP-seq and ChIP-qPCR analyses revealed significant enrichment of H3K27ac in the STEAP3 gene. In addition, knocking down STEAP3 significantly inhibits colon cancer cell proliferation and migration and down-regulates H3K27ac expression. ChIP-seq found that ATF3 is enriched in the STEAP3 gene and CRISPR/Cas9 technology used for the deletion of the ATF3 binding site suppresses the expression of STEAP3. Over-expression of STEAP3 promotes colon cancer cell proliferation and migration. Mechanical studies have indicated that H3K27ac and ATF3 are significantly enriched in the STEAP3 gene and regulate the over-expression of STEAP3.

Targeting Histone 3 Variants Epigenetic Landscape and Inhibitory Immune Checkpoints: An Option for Paediatric Brain Tumours Therapy

Despite little progress in survival rates with regular therapies, which do not provide complete care for curing pediatric brain tumors (PBTs), there is an urgent need for novel strategies to overcome the toxic effects of conventional therapies to treat PBTs. The co-inhibitory immune checkpoint molecules, e.g., CTLA-4, PD-1/PD-L1, etc., and epigenetic alterations in histone variants, e.g., H3K27me3 that help in immune evasion at tumor microenvironment have not gained much attention in PBTs treatment. However, key epigenetic mechanistic alterations, such as acetylation, methylation, phosphorylation, sumoylation, poly (ADP)-ribosylation, and ubiquitination in histone protein, are greatly acknowledged. The crucial checkpoints in pediatric brain tumors are cytotoxic T lymphocyte antigen-4 (CTLA-4), programmed cell death protein-1 (PD-1) and programmed death-ligand 1 (PDL1), OX-2 membrane glycoprotein (CD200), and indoleamine 2,3-dioxygenase (IDO). This review covers the state of knowledge on the role of multiple co-inhibitory immunological checkpoint proteins and histone epigenetic alterations in different cancers. We further discuss the processes behind these checkpoints, cell signalling, the current scenario of clinical and preclinical research and potential futuristic opportunities for immunotherapies in the treatment of pediatric brain tumors. Conclusively, this article further discusses the possibilities of these interventions to be used for better therapy options.

Review on Pediatric Malignant Focal Liver Lesions with Imaging Evaluation: Part II

Malignant focal liver lesions (FLLs) represent various kinds of epithelial and mesenchymal tumors. In pediatric patients, the understanding of pediatric liver diseases and associated imaging manifestations is essential for making accurate diagnosis and differential diagnosis. This paper will discuss the latest knowledge of the common pediatric malignant FLLs, including undifferentiated embryonal sarcoma, rhabdomyosarcoma, epithelioid hemangioendothelioma, angiosarcoma, and malignant rhabdoid tumor. Medical imaging features are not only helpful for clinical diagnosis, but can also be useful in the evaluation and follow-up of pre- and post-treatment. The future perspectives of contrast-enhanced ultrasound (CEUS) enhancement patterns of FLLs in pediatric patients are also mentioned.

Changes on chromosome 11p15.5 as specific marker for embryonal rhabdomyosarcoma?

Rhabdomyosarcomas (RMS) constitute a heterogeneous spectrum of tumors with respect to clinical behavior and tumor morphology. The paternal uniparental disomy (pUPD) of 11p15.5 is a molecular change described mainly in embryonal RMS. In addition to LOH, UPD, the MLPA technique (ME030kit) also determines copy number variants and methylation of H19 and KCNQ1OT1 genes, which have not been systematically investigated in RMS. All 127 RMS tumors were divided by histology and PAX status into four groups, pleomorphic histology (n = 2); alveolar RMS PAX fusion-positive (PAX+; n = 39); embryonal RMS (n = 70) and fusion-negative RMS with alveolar pattern (PAX-RMS-AP; n = 16). The following changes were detected; negative (n = 21), pUPD (n = 75), gain of paternal allele (n = 9), loss of maternal allele (n = 9), hypermethylation of H19 (n = 6), hypomethylation of KCNQ1OT1 (n = 6), and deletion of CDKN1C (n = 1). We have shown no difference in the frequency of pUPD 11p15.5 in all groups. Thus, we have proven that changes in the 11p15.5 are not only specific to the embryonal RMS (ERMS), but are often also present in alveolar RMS (ARMS). We have found changes that have not yet been described in RMS. We also demonstrated new potential diagnostic markers for ERMS (paternal duplication and UPD of whole chromosome 11) and for ARMS PAX+ (hypomethylation KCNQ1OT1).

Drug-induced loss of imprinting revealed using bioluminescent reporters of Cdkn1c

Genomic imprinting is an epigenetically mediated mechanism that regulates allelic expression of genes based upon parent-of-origin and provides a paradigm for studying epigenetic silencing and release. Here, bioluminescent reporters for the maternally-expressed imprinted gene Cdkn1c are used to examine the capacity of chromatin-modifying drugs to reverse paternal Cdkn1c silencing. Exposure of reporter mouse embryonic stem cells (mESCs) to 5-Azacytidine, HDAC inhibitors, BET inhibitors or GSK-J4 (KDM6A/B inhibitor) relieved repression of paternal Cdkn1c, either selectively or by inducing biallelic effects. Treatment of reporter fibroblasts with HDAC inhibitors or GSK-J4 resulted in similar paternal Cdkn1c activation, whereas BET inhibitor-induced loss of imprinting was specific to mESCs. Changes in allelic expression were generally not sustained in dividing cultures upon drug removal, indicating that the underlying epigenetic memory of silencing was maintained. In contrast, Cdkn1c de-repression by GSK-J4 was retained in both mESCs and fibroblasts following inhibitor removal, although this impact may be linked to cellular stress and DNA damage. Taken together, these data introduce bioluminescent reporter cells as tools for studying epigenetic silencing and disruption, and demonstrate that Cdkn1c imprinting requires distinct and cell-type specific chromatin features and modifying enzymes to enact and propagate a memory of silencing.

The FOXM1/RNF26/p57 axis regulates the cell cycle to promote the aggressiveness of bladder cancer

Bladder cancer is one of the most lethal cancers in the world. Despite the continuous development of medical technologies and therapeutic strategies, the overall survival rate of bladder cancer has not changed significantly. Targeted therapy is a new promising method for bladder cancer treatment. Thus, an in-depth study of the molecular mechanism of the occurrence and development of bladder cancer is urgently needed to identify novel therapeutic candidates for bladder cancer. Here, bioinformatics analysis demonstrated that RNF26 was one of the risk factors for bladder cancer. Then, we showed that RNF26 is abnormally upregulated in bladder cancer cells and tissues and that higher RNF26 expression is an unfavorable prognostic factor for bladder cancer. Moreover, we found that RNF26 promotes bladder cancer progression. In addition, we showed that RNF26 expression is promoted by FOXM1 at the transcriptional level through MuvB complex. The upregulated RNF26 in turn degrades p57 (CDKN1C) to regulate the cell cycle process. Collectively, we uncovered a novel FOXM1/RNF26/p57 axis that modulates the cell cycle process and enhances the progression of bladder cancer. Thus, the FOXM1/RNF26/p57 signaling axis could be a candidate target for the treatment of bladder cancer.

Atypical Teratoid Rhabdoid Tumours Are Susceptible to Panobinostat-Mediated Differentiation Therapy

Simple Summary

Atypical teratoid rhabdoid tumour (ATRT) is an aggressive undifferentiated malignancy of the central nervous system in children. A defining feature of ATRT is the loss of the SMARCB1 gene that is essential for regulating gene expression required for normal developmental processes. We show that treatment of human ATRT cell models with the histone deacetylate inhibitor, panobinostat, inhibits tumour growth, reactivates the expression of developmental genes, and drives neuronal differentiation. These results demonstrate the therapeutic potential of panobinostat for the treatment of ATRT.

Abstract

Atypical teratoid rhabdoid tumour (ATRT) is a rare but highly aggressive undifferentiated solid tumour arising in the central nervous system and predominantly affecting infants and young children. ATRT is exclusively characterized by the inactivation of SMARCB1, a member of the SWI/SNF chromatin remodelling complex that is essential for the regulation of large sets of genes required for normal development and differentiation. Histone deacetylase inhibitors (HDACi) are a promising anticancer therapy and are able to mimic the normal acetylation functions of SMARCB1 in SMARCB1-deficient cells and drive multilineage differentiation in extracranial rhabdoid tumours. However, the potential efficacy of HDACi in ATRT is unknown. Here, we show that human ATRT cells are highly responsive to the HDACi panobinostat and that sustained treatment leads to growth arrest, increased cell senescence, decreased clonogenicity and induction of a neurogenesis gene-expression profile. Furthermore, in an orthotopic ATRT xenograft model, continuous panobinostat treatment inhibits tumour growth, increases survival and drives neuronal differentiation as shown by the expression of the neuronal marker, TUJ1. Collectively, this preclinical study supports the therapeutic potential of panobinostat-mediated differentiation therapy for ATRT.

Histone deacetylase inhibitor panobinostat induces antitumor activity in epithelioid sarcoma and rhabdoid tumor by growth factor receptor modulation

Background

Epithelioid sarcomas and rhabdoid tumors are rare, aggressive malignancies with poor prognosis. Both are characterized by INI1 alterations and deregulation of growth factor receptors albeit their interaction has not been elucidated.

Methods

In this study, we investigated the activity of a panel of epigenetic modulators and receptor tyrosine kinase inhibitors in vitro on respective cell lines as well as on primary patient-derived epithelioid sarcoma cells, and in vivo on xenografted mice. Focusing on histone deacetylase (HDAC) inhibitors, we studied the mechanism of action of this class of agents, its effect on growth factor receptor regulation, and changes in epithelial-to-mesenchymal transition by using cell- and RT-qPCR-based assays.

Results

Pan-HDAC inhibitor panobinostat exhibited potent anti-proliferative activity at low nanomolar concentrations in A204 rhabdoid tumor, and VAESBJ/GRU1 epithelioid sarcoma cell lines, strongly induced apoptosis, and resulted in significant tumor growth inhibition in VAESBJ xenografts. It differentially regulated EGFR, FGFR1 and FGFR2, leading to downregulation of EGFR in epithelioid sarcoma and to mesenchymal-to-epithelial transition whereas in rhabdoid tumor cells, EGFR was strongly upregulated and reinforced the mesenchymal phenotype. All three cell lines were rendered more susceptible towards combination with EGFF inhibitor erlotinib, further enhancing apoptosis.

Conclusions

HDAC inhibitors exhibit significant anticancer activity due to their multifaceted actions on cytotoxicity, differentiation and drug sensitization. Our data suggest that the tailored, tissue-specific combination of HDAC inhibitors with therapeutics which target cellular salvage mechanisms might increase their therapeutic relevance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08579-w.

Current Understanding of Neurofibromatosis Type 1, 2, and Schwannomatosis

Neurofibromatosis (NF) is a neurocutaneous syndrome characterized by the development of tumors of the central or peripheral nervous system including the brain, spinal cord, organs, skin, and bones. There are three types of NF: NF1 accounting for 96% of all cases, NF2 in 3%, and schwannomatosis (SWN) in <1%. The NF1 gene is located on chromosome 17q11.2, which encodes for a tumor suppressor protein, neurofibromin, that functions as a negative regulator of Ras/MAPK and PI3K/mTOR signaling pathways. The NF2 gene is identified on chromosome 22q12, which encodes for merlin, a tumor suppressor protein related to ezrin-radixin-moesin that modulates the activity of PI3K/AKT, Raf/MEK/ERK, and mTOR signaling pathways. In contrast, molecular insights on the different forms of SWN remain unclear. Inactivating mutations in the tumor suppressor genes SMARCB1 and LZTR1 are considered responsible for a majority of cases. Recently, treatment strategies to target specific genetic or molecular events involved in their tumorigenesis are developed. This study discusses molecular pathways and related targeted therapies for NF1, NF2, and SWN and reviews recent clinical trials which involve NF patients.

Epigenetic mechanisms involved in intrauterine growth restriction and aberrant kidney development and function

Intrauterine growth restriction (IUGR) due to uteroplacental insufficiency results in a placenta that is unable to provide adequate nutrients and oxygen to the fetus. These growth-restricted babies have an increased risk of hypertension and chronic kidney disease later in life. In rats, both male and female growth-restricted offspring have nephron deficits but only males develop kidney dysfunction and high blood pressure. In addition, there is transgenerational transmission of nephron deficits and hypertension risk. Therefore, epigenetic mechanisms may explain the sex-specific programming and multigenerational transmission of IUGR-related phenotypes. Expression of DNA methyltransferases (Dnmt1and Dnmt3a) and imprinted genes (Peg3, Snrpn, Kcnq1, and Cdkn1c) were investigated in kidney tissues of sham and IUGR rats in F1 (embryonic day 20 (E20) and postnatal day 1 (PN1)) and F2 (6 and 12 months of age, paternal and maternal lines) generations (n = 6-13/group). In comparison to sham offspring, F1 IUGR rats had a 19% decrease in Dnmt3a expression at E20 (P < 0.05), with decreased Cdkn1c (19%, P < 0.05) and increased Kcnq1 (1.6-fold, P < 0.01) at PN1. There was a sex-specific difference in Cdkn1c and Snrpn expression at E20, with 29% and 34% higher expression in IUGR males compared to females, respectively (P < 0.05). Peg3 sex-specific expression was lost in the F2 IUGR offspring, only in the maternal line. These findings suggest that epigenetic mechanisms may be altered in renal embryonic and/or fetal development in growth-restricted offspring, which could alter kidney function, predisposing these offspring to kidney disease later in life.

Regulation of p27Kip1 and p57Kip2 Functions by Natural Polyphenols

In numerous instances, the fate of a single cell not only represents its peculiar outcome but also contributes to the overall status of an organism. In turn, the cell division cycle and its control strongly influence cell destiny, playing a critical role in targeting it towards a specific phenotype. Several factors participate in the control of growth, and among them, p27^Kip1 and p57^Kip2, two proteins modulating various transitions of the cell cycle, appear to play key functions. In this review, the major features of p27 and p57 will be described, focusing, in particular, on their recently identified roles not directly correlated with cell cycle modulation. Then, their possible roles as molecular effectors of polyphenols’ activities will be discussed. Polyphenols represent a large family of natural bioactive molecules that have been demonstrated to exhibit promising protective activities against several human diseases. Their use has also been proposed in association with classical therapies for improving their clinical effects and for diminishing their negative side activities. The importance of p27^Kip1 and p57^Kip2 in polyphenols’ cellular effects will be discussed with the aim of identifying novel therapeutic strategies for the treatment of important human diseases, such as cancers, characterized by an altered control of growth.

Histone Deacetylase Inhibitors in Pediatric Brain Cancers: Biological Activities and Therapeutic Potential

Brain cancers are the leading cause of cancer-related deaths in children. Biological changes in these tumors likely include epigenetic deregulation during embryonal development of the nervous system. Histone acetylation is one of the most widely investigated epigenetic processes, and histone deacetylase inhibitors (HDACis) are increasingly important candidate treatments in many cancer types. Here, we review advances in our understanding of how HDACis display antitumor effects in experimental models of specific pediatric brain tumor types, i.e., medulloblastoma (MB), ependymoma (EPN), pediatric high-grade gliomas (HGGs), and rhabdoid and atypical teratoid/rhabdoid tumors (ATRTs). We also discuss clinical perspectives for the use of HDACis in the treatment of pediatric brain tumors.

Epigenetic synthetic lethality approaches in cancer therapy

The onset and development of malignant tumors are closely related to epigenetic modifications, and this has become a research hotspot. In recent years, a variety of epigenetic regulators have been discovered, and corresponding small molecule inhibitors have been developed, but their efficacy in solid tumors is generally poor. With the introduction of the first synthetic lethal drug (the PARP inhibitor olaparib in ovarian cancer with BRCA1 mutation), research into synthetic lethality has also become a hotspot. High-throughput screening with CRISPR-Cas9 and shRNA technology has revealed a large number of synthetic lethal pairs involving epigenetic-related synthetic lethal genes, such as those encoding SWI/SNF complex subunits, PRC2 complex subunits, SETD2, KMT2C, and MLL fusion proteins. In this review, we focus on epigenetic-related synthetic lethal mechanisms, including synthetic lethality between epigenetic mutations and epigenetic inhibitors, epigenetic mutations and non-epigenetic inhibitors, and oncogene mutations and epigenetic inhibitors.

TCF4 (E2-2) harbors tumor suppressive functions in SHH medulloblastoma

The TCF4 gene encodes for the basic helix-loop-helix transcription factor 4 (TCF4), which plays an important role in the development of the central nervous system (CNS). Haploinsufficiency of TCF4 was found to cause Pitt-Hopkins syndrome (PTHS), a severe neurodevelopmental disorder. Recently, the screening of a large cohort of medulloblastoma (MB), a highly aggressive embryonal brain tumor, revealed almost 20% of adult patients with MB of the Sonic hedgehog (SHH) subtype carrying somatic TCF4 mutations. Interestingly, many of these mutations have previously been detected as germline mutations in patients with PTHS. We show here that overexpression of wild-type TCF4 in vitro significantly suppresses cell proliferation in MB cells, whereas mutant TCF4 proteins do not to the same extent. Furthermore, RNA sequencing revealed significant upregulation of multiple well-known tumor suppressors upon expression of wild-type TCF4. In vivo, a prenatal knockout of Tcf4 in mice caused a significant increase in apoptosis accompanied by a decreased proliferation and failed migration of cerebellar granule neuron precursor cells (CGNP), which are thought to be the cells of origin for SHH MB. In contrast, postnatal in vitro and in vivo knockouts of Tcf4 with and without an additional constitutive activation of the SHH pathway led to significantly increased proliferation of CGNP or MB cells. Finally, publicly available data from human MB show that relatively low expression levels of TCF4 significantly correlate with a worse clinical outcome. These results not only point to time-specific roles of Tcf4 during cerebellar development but also suggest a functional linkage between TCF4 mutations and the formation of SHH MB, proposing that TCF4 acts as a tumor suppressor during postnatal stages of cerebellar development.

Genetic and Epigenetic Control of CDKN1C Expression: Importance in Cell Commitment and Differentiation, Tissue Homeostasis and Human Diseases

The CDKN1C gene encodes the p57^Kip2 protein which has been identified as the third member of the CIP/Kip family, also including p27^Kip1 and p21^Cip1. In analogy with these proteins, p57^Kip2 is able to bind tightly and inhibit cyclin/cyclin-dependent kinase complexes and, in turn, modulate cell division cycle progression. For a long time, the main function of p57^Kip2 has been associated only to correct embryogenesis, since CDKN1C-ablated mice are not vital. Accordingly, it has been demonstrated that CDKN1C alterations cause three human hereditary syndromes, characterized by altered growth rate. Subsequently, the p57^Kip2 role in several cell phenotypes has been clearly assessed as well as its down-regulation in human cancers. CDKN1C lies in a genetic locus, 11p15.5, characterized by a remarkable regional imprinting that results in the transcription of only the maternal allele. The control of CDKN1C transcription is also linked to additional mechanisms, including DNA methylation and specific histone methylation/acetylation. Finally, long non-coding RNAs and miRNAs appear to play important roles in controlling p57^Kip2 levels. This review mostly represents an appraisal of the available data regarding the control of CDKN1C gene expression. In addition, the structure and function of p57^Kip2 protein are briefly described and correlated to human physiology and diseases.

Loss of CDKN1C in a Recurrent Atypical Teratoid/Rhabdoid Tumor

Atypical teratoid/rhabdoid tumor (AT/RT) is a malignant tumor that is commonly associated with biallelic alterations of SMARCB1. Recurrent or refractory AT/RT has not been molecularly characterized as well. We present the case of a child with recurrent AT/RT who underwent clinically integrated molecular profiling (germline DNA and tumor DNA/RNA sequencing). This demonstrated a somatic lesion in CDKN1C alongside hallmark loss of SMARCB1. This data allowed us to explore potential personalized therapies for this patient and expose a molecular driver that may be involved in similar cases.

Epigenetic modification in chromatin machinery and its deregulation in pediatric brain tumors: Insight into epigenetic therapies

Malignancies are characterized by the reprogramming of epigenetic patterns. This reprogramming includes gains or losses in DNA methylation and disruption of normal patterns of covalent histone modifications, which are associated with changes in chromatin remodeling processes. This review will focus on the mechanisms underlying this reprogramming and, specifically, on the role of histone modification in chromatin machinery and the modifications in epigenetic processes occurring in brain cancer, with a specific focus on epigenetic therapies for pediatric brain tumors.

Disrupting LIN28 in atypical teratoid rhabdoid tumors reveals the importance of the mitogen activated protein kinase pathway as a therapeutic target

Atypical teratoid rhabdoid tumor (AT/RT) is among the most fatal of all pediatric brain tumors. Aside from loss of function mutations in the SMARCB1 (BAF47/INI1/SNF5) chromatin remodeling gene, little is known of other molecular drivers of AT/RT. LIN28A and LIN28B are stem cell factors that regulate thousands of RNAs and are expressed in aggressive cancers. We identified high-levels of LIN28A and LIN28B in AT/RT primary tumors and cell lines, with corresponding low levels of the LIN28-regulated microRNAs of the let-7 family. Knockdown of LIN28A by lentiviral shRNA in the AT/RT cell lines CHLA-06-ATRT and BT37 inhibited growth, cell proliferation and colony formation and induced apoptosis. Suppression of LIN28A in orthotopic xenograft models led to a more than doubling of median survival compared to empty vector controls (48 vs 115 days). LIN28A knockdown led to increased expression of let-7b and let-7g microRNAs and a down-regulation of KRAS mRNA. AT/RT primary tumors expressed increased mitogen activated protein (MAP) kinase pathway activity, and the MEK inhibitor selumetinib (AZD6244) decreased AT/RT growth and increased apoptosis. These data implicate LIN28/RAS/MAP kinase as key drivers of AT/RT tumorigenesis and indicate that targeting this pathway may be a therapeutic option in this aggressive pediatric malignancy.

Low-Dose Histone Deacetylase Inhibitor Treatment Leads to Tumor Growth Arrest and Multi-Lineage Differentiation of Malignant Rhabdoid Tumors

PURPOSE

Malignant rhabdoid tumor (MRT) and atypical teratoid rhabdoid tumors (ATRT) are rare aggressive undifferentiated tumors primarily affecting the kidney and CNS of infants and young children. MRT are almost exclusively characterized by homozygous deletion or inactivation of the chromatin remodeling gene SMARCB1 SMARCB1 protein loss leads to direct impairment of chromatin remodeling and we have previously reported a role for this protein in histone acetylation. This provided the rationale for investigating the therapeutic potential of histone deactylase inhibitors (HDACi) in MRT.

EXPERIMENTAL DESIGN

Whereas previously HDACis have been used at doses and schedules that induce cytotoxicity, in the current studies we have tested the hypothesis, both in vitro and in vivo, that sustained treatment of human MRT with low-dose HDACi can lead to sustained cell growth arrest and differentiation.

RESULTS

Sustained low-dose panobinostat (LBH589) treatment led to changes in cellular morphology associated with a marked increase in the induction of neural, renal, and osteoblast differentiation pathways. Genome-wide transcriptional profiling highlighted differential gene expression supporting multilineage differentiation. Using mouse xenograft models, sustained low-dose LBH589 treatment caused tumor growth arrest associated with tumor calcification detectable by X-ray imaging. Histological analysis of LBH589-treated tumors revealed significant regions of ossification, confirmed by Alizarin Red staining. Immunohistochemical analysis showed increased TUJ1 and PAX2 staining suggestive of neuronal and renal differentiation, respectively.

CONCLUSIONS

Low-dose HDACi treatment can terminally differentiate MRT tumor cells and reduce their ability to self-renew. The use of low-dose HDACi as a novel therapeutic approach warrants further investigation. Clin Cancer Res; 22(14); 3560-70. ©2016 AACR.

Identification of potential therapeutic targets for papillary thyroid carcinoma by bioinformatics analysis

The aim of the present study was to identify potential therapeutic targets for papillary thyroid carcinoma (PTC) and to investigate the possible mechanism underlying this disease. The gene expression profile, GSE53157, was downloaded from the Gene Expression Omnibus database. Only 10 chips, including 3 specimens of normal thyroid tissues and 7 specimens of well-differentiated thyroid carcinomas, were analyzed in the present study. Differentially-expressed genes (DEGs) between PTC patients and normal individuals were identified. Next, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses of DEGs were performed. Modules in the protein-protein interaction (PPI) network were identified. Significant target genes were selected from the microRNA (miRNA) regulatory network. Furthermore, the integrated network was constructed with the miRNA regulatory and PPI network modules, and key target genes were screened. A total of 668 DEGs were identified. Modules M1, M2 and M3 were identified from the PPI network. From the modules, DEGs of cyclin-dependent kinase inhibitor 1A, S100 calcium binding protein A6 (S100A6), dual specificity phosphatase 5, keratin 19, met proto-oncogene (MET) and lectin galactoside-binding soluble 3 were included in the Malacards database. In the miRNA regulatory and integrated networks, genes of cyclin-dependent kinase inhibitor 1C (CDKN1C), peroxisome proliferator-activated receptor γ, aryl hydrocarbon receptor, basic helix-loop-helix family, member e40 and reticulon 1 were the key target genes. S100A6, MET and CDKN1C may exhibit key roles in the progression and development of PTC, and may be used as specific therapeutic targets in the treatment of PTC. However, further experiments are required to confirm these results.

Integrated genome-wide analysis of genomic changes and gene regulation in human adrenocortical tissue samples

To gain insight into the pathogenesis of adrenocortical carcinoma (ACC) and whether there is progression from normal-to-adenoma-to-carcinoma, we performed genome-wide gene expression, gene methylation, microRNA expression and comparative genomic hybridization (CGH) analysis in human adrenocortical tissue (normal, adrenocortical adenomas and ACC) samples. A pairwise comparison of normal, adrenocortical adenomas and ACC gene expression profiles with more than four-fold expression differences and an adjusted P-value < 0.05 revealed no major differences in normal versus adrenocortical adenoma whereas there are 808 and 1085, respectively, dysregulated genes between ACC versus adrenocortical adenoma and ACC versus normal. The majority of the dysregulated genes in ACC were downregulated. By integrating the CGH, gene methylation and expression profiles of potential miRNAs with the gene expression of dysregulated genes, we found that there are higher alterations in ACC versus normal compared to ACC versus adrenocortical adenoma. Importantly, we identified several novel molecular pathways that are associated with dysregulated genes and further experimentally validated that oncostatin m signaling induces caspase 3 dependent apoptosis and suppresses cell proliferation. Finally, we propose that there is higher number of genomic changes from normal-to-adenoma-to-carcinoma and identified oncostatin m signaling as a plausible druggable pathway for therapeutics.

Malignant rhabdoid tumor of kidney and brain in an infant

BACKGROUND

Malignant rhabdoid tumors of kidney are associated with atypical teratoid rhabdoid tumors of brain, both being characterized genetically by deletion/ mutation of SMAR CBI/ INI gene.

CASE CHARACTERISTICS

6-month-old male presented with a brain tumor and was subsequently found to have malignant rhabdoid tumor of kidney.

INTERVENTIONS

Surgical resection of brain tumor followed by chemotherapy and subsequently resection of renal tumor.

OUTCOME

Child died seven months after initial presentation.

MESSAGE

Children presenting with embroynal brain tumor, should be investigated for renal tumors and vice versa.

MESSAGE

Children presenting with embroynal brain tumor, should be investigated for renal tumors and vice versa.

Evidence of an oncogenic role of aberrant TOX activation in cutaneous T-cell lymphoma

TOX is a nuclear factor essential for the development of CD4(+) T cells in the thymus. It is normally expressed in low amounts in mature CD4(+) T cells of the skin and the peripheral blood. We have recently discovered that the transcript levels of TOX were significantly increased in mycosis fungoides, the most common type of cutaneous T-cell lymphoma (CTCL), as compared to normal skin or benign inflammatory dermatoses. However, its involvement in advanced CTCL and its biological effects on CTCL pathogenesis have not been explored. In this study, we demonstrate that TOX expression is also enhanced significantly in primary CD4(+)CD7(-) cells from patients with Sézary syndrome, a leukemic variant of CTCL, and that high TOX transcript levels correlate with increased disease-specific mortality. Stable knockdown of TOX in CTCL cells promoted apoptosis and reduced cell cycle progression, leading to less cell viability and colony-forming ability in vitro and to reduced tumor growth in vivo. Furthermore, TOX knockdown significantly increased 2 cyclin-dependent kinase (CDK) inhibitors, CDKN1B and CDKN1C. Lastly, blocking CDKN1B and CDKN1C reversed growth inhibition of TOX knockdown. Collectively, these findings provide strong evidence that aberrant TOX activation is a critical oncogenic event for CTCL.

Expression Profiling and Proteomic Analysis of JIN Chinese Herbal Formula in Lung Carcinoma H460 Xenografts

Many traditional Chinese medicine (TCM) formulae have been used in cancer therapy. The JIN formula is an ancient herbal formula recorded in the classic TCM book Jin Kui Yao Lue (Golden Chamber). The JIN formula significantly delayed the growth of subcutaneous human H460 xenografted tumors in vivo compared with the growth of mock controls. Gene array analysis of signal transduction in cancer showed that the JIN formula acted on multiple targets such as the mitogen-activated protein kinase, hedgehog, and Wnt signaling pathways. The coformula treatment of JIN and diamminedichloroplatinum (DDP) affected the stress/heat shock pathway. Proteomic analysis showed 36 and 84 differentially expressed proteins between the mock and DDP groups and between the mock and JIN groups, respectively. GoMiner analysis revealed that the differentially expressed proteins between the JIN and mock groups were enriched during cellular metabolic processes, and so forth. The ones between the DDP and mock groups were enriched during protein-DNA complex assembly, and so forth. Most downregulated proteins in the JIN group were heat shock proteins (HSPs) such as HSP90AA1 and HSPA1B, which could be used as markers to monitor responses to the JIN formula therapy. The mechanism of action of the JIN formula on HSP proteins warrants further investigation.

Pediatric rhabdoid tumors of kidney and brain show many differences in gene expression but share dysregulation of cell cycle and epigenetic effector genes

BACKGROUND

Rhabdoid tumors (RTs) are aggressive tumors of early childhood that occur most often in brain (AT/RTs) or kidney (KRTs). Regardless of location, they are characterized by loss of functional SMARCB1 protein, a component of the SWI/SNF chromatin remodeling complex. The aim of this study was to determine genes and biological process dysregulated in common to both AT/RTs and KRTs.

PROCEDURE

Gene expression for AT/RTs was compared to that of other brain tumors and normal brain using microarray data from our lab. Similar analysis was performed for KRTs and other kidney tumors and normal kidney using data from GEO. Dysregulated genes common to both analyses were analyzed for functional significance.

RESULTS

Unsupervised hierarchical clustering of RTs identified three major subsets: two comprised of AT/RTs, and one of KRTs. Compared to other tumors, 1,187, 663, and 539 genes were dysregulated in each subset, respectively. Only 14 dysregulated genes were common to all three subsets. Compared to normal tissue, 5,209, 4,275, and 2,841 genes were dysregulated in each subset, with an overlap of 610 dysregulated genes. Among these genes, processes associated with cell proliferation, MYC activation, and epigenetic dysregulation were common to all three RT subsets.

CONCLUSIONS

The low overlap of dysregulated genes in AT/RTs and KRTs suggests that factors in addition to SMARCB1 loss play a role in determining subsequent gene expression. Drugs which target cell cycle or epigenetic genes may be useful in all RTs. Additionally, targeted therapies tailored to specific RT subset molecular profiles should be considered.

The histone deacetylase inhibitor SAHA acts in synergism with fenretinide and doxorubicin to control growth of rhabdoid tumor cells

BACKGROUND

Rhabdoid tumors are highly aggressive malignancies affecting infants and very young children. In many instances these tumors are resistant to conventional type chemotherapy necessitating alternative approaches.

METHODS

Proliferation assays (MTT), apoptosis (propidium iodide/annexin V) and cell cycle analysis (DAPI), RNA expression microarrays and western blots were used to identify synergism of the HDAC (histone deacetylase) inhibitor SAHA with fenretinide, tamoxifen and doxorubicin in rhabdoidtumor cell lines.

RESULTS

HDAC1 and HDAC2 are overexpressed in primary rhabdoid tumors and rhabdoid tumor cell lines. Targeting HDACs in rhabdoid tumors induces cell cycle arrest and apoptosis. On the other hand HDAC inhibition induces deregulated gene programs (MYCC-, RB program and the stem cell program) in rhabdoid tumors. These programs are in general associated with cell cycle progression. Targeting these activated pro-proliferative genes by combined approaches of HDAC-inhibitors plus fenretinide, which inhibits cyclinD1, exhibit strong synergistic effects on induction of apoptosis. Furthermore, HDAC inhibition sensitizes rhabdoid tumor cell lines to cell death induced by chemotherapy.

CONCLUSION

Our data demonstrate that HDAC inhibitor treatment in combination with fenretinide or conventional chemotherapy is a promising tool for the treatment of chemoresistant rhabdoid tumors.

Disomy as the genetic underlying mechanisms of loss of heterozigosity in SDHD-paragangliomas

CONTEXT

Succinate dehydrogenase complex, subunit D (SDHD) mutations cause pheochromocytoma/paraganglioma syndrome. SDHD, located at chromosome 11q23, shows a parent-of-origin effect because the disease is observed almost exclusively when the mutation is transmitted from the father, although some cases of maternal transmission have been reported. Several hypotheses have been proposed for this peculiar inheritance pattern, but the underlying mechanisms have not yet been clearly elucidated.

OBJECTIVE

The objective of the study was to explain the parent-of-origin effect in a family, mainly affected by paternally transmitted paragangliomas, and with a maternally transmitted renal tumor.

PATIENTS

Peripheral blood DNA from 15 carriers and 7 tumor DNA samples from SDHD-p.Trp5* carriers were studied.

METHODS

We conducted mutation genotyping and microsatellite marker analysis in germline and tumor DNA and methylation status analysis in tumor DNA by methylation-specific multiplex ligation-dependent probe amplification.

RESULTS

Mutation genotyping and microsatellite marker analysis demonstrated loss of heterozygosity of the wild-type allele (maternal) in all studied tumors, except the renal tumor, which lost the mutated allele (maternal), and the prostate tumor, which had no loss of heterozygosity. The methylation-specific multiplex ligation-dependent probe amplification demonstrated that the methylation profile corresponded exclusively to the paternal chromosome without genomic loss, suggesting paternal uniparental disomy as the mechanism underlying the parent-of-origin effect in this SDHD family.

CONCLUSIONS

The paternal uniparental disomy involves the loss of maternally imprinted cell cycle regulators and the overexpression of paternally imprinted growth activators, leading to tumorigenesis in this syndrome.

Bilateral pheochromocytomas, hemihyperplasia, and subtle somatic mosaicism: the importance of detecting low-level uniparental disomy

We report on a patient with early onset pediatric bilateral pheochromocytomas caused by mosaic chromosome 11p15 paternal uniparental isodisomy (UPD). Hemihyperplasia of the arm was diagnosed in a 4-month-old female and clinical methylation testing for 11p15 in the blood was normal, with a reported detection threshold for mosaicism of 20%. She was subsequently diagnosed at 18 months with bilateral pheochromocytomas. Single-nucleotide polymorphism (SNP) array analysis of pheochromocytoma tissue demonstrated mosaic deletions of 8p12pter, 21q21.1qter, 22q11.23qter; commonly seen in pheochromocytomas. In addition, mosaic 11p15.3pter homozygosity was noted. Molecular testing for other causes of pheochromocytomas was normal, suggesting that 11p15 homozygosity was the primary event. Subsequent SNP array analysis of skin fibroblasts from the hyperplastic side demonstrated 5% mosaic paternal UPD for 11p15. We have subsequently used SNP array analysis to identify four patients with subtle hemihyperplasia with low-level mosaic UPD that was not detected by methylation analysis. Given the increased sensitivity of SNP array analysis to detect UPD along with the increased incidence of tumorigenesis in these UPD patients, we suggest that it has high utility in the clinical work-up of hemihyperplasia. The present case also suggests that 11p15 paternal UPD may be an under-detected mechanism of sporadic pheochromocytoma in the pediatric population. Furthermore, a review of the literature suggests that patients with 11p15 paternal UPD may present after 8 years of age with pheochromocytoma and raises the possibility that ultrasound screening could be considered beyond 8 years of age in this subset of hemihyperplasia and Beckwith-Wiedemann syndrome patients.

Histone deacetylases expression in atypical teratoid rhabdoid tumors

PURPOSE

Atypical teratoid rhabdoid tumors (ATRTs) are rare, highly malignant central nervous system tumors that occur during infancy and early childhood. Their poor outcome and resistance to conventional chemotherapies and radiotherapy, urges the development of new therapies. Recent studies have evaluated the effects of histone deacetylase inhibitors (HDACi) as a new potential treatment for ATRTs. However, most HDACi act unselectively against all, or at least several, histone deacetylase (HDAC) family members. We hypothesized that specific HDAC family members are deregulated in ATRT and therefore a more selective class of HDACi would be beneficial to patients with ATRT.

METHODS

To test our hypothesis, we evaluated the expression level of different HDAC family members in ATRTs. Eight ATRTs were compared to six medulloblastoma samples in regards to the level of expression of the 18 HDAC family members as determined by microarray gene expression profiling.

RESULTS

HDAC1 was the only member of the HDAC family to be significantly differentially expressed in ATRTs (FC = 4.728; p value = 0.00003).

CONCLUSIONS

A class of HDACi specifically targeting HDAC1 may allow for the desired therapeutic benefits with fewer side effects for children with ATRT.

The multiple roles of the cyclin-dependent kinase inhibitory protein p57(KIP2) in cerebral cortical neurogenesis

The members of the CIP/KIP family of cyclin-dependent kinase (CDK) inhibitory proteins (CKIs), including p57(KIP2), p27(KIP1), and p21(CIP1), block the progression of the cell cycle by binding and inhibiting cyclin/CDK complexes of the G1 phase. In addition to this well-characterized function, p57(KIP2) and p27(KIP1) have been shown to participate in an increasing number of other important cellular processes including cell fate and differentiation, cell motility and migration, and cell death/survival, both in peripheral and central nervous systems. Increasing evidence over the past few years has characterized the functions of the newest CIP/KIP member p57(KIP2) in orchestrating cell proliferation, differentiation, and migration during neurogenesis. Here, we focus our discussion on the multiple roles played by p57(KIP2) during cortical development, making comparisons to p27(KIP1) as well as the INK4 family of CKIs.

Specific changes in the expression of imprinted genes in prostate cancer--implications for cancer progression and epigenetic regulation

Epigenetic dysregulation comprising DNA hypermethylation and hypomethylation, enhancer of zeste homologue 2 (EZH2) overexpression and altered patterns of histone modifications is associated with the progression of prostate cancer. DNA methylation, EZH2 and histone modifications also ensure the parental-specific monoallelic expression of at least 62 imprinted genes. Although it is therefore tempting to speculate that epigenetic dysregulation may extend to imprinted genes, expression changes in cancerous prostates are only well documented for insulin-like growth factor 2 (IGF2). A literature and database survey on imprinted genes in prostate cancer suggests that the expression of most imprinted genes remains unchanged despite global disturbances in epigenetic mechanisms. Instead, selective genetic and epigenetic changes appear to lead to the inactivation of a sub-network of imprinted genes, which might function in the prostate to limit cell growth induced via the PI3K/Akt pathway, modulate androgen responses and regulate differentiation. Whereas dysregulation of IGF2 may constitute an early change in prostate carcinogenesis, inactivation of this imprinted gene network is rather associated with cancer progression.

Histone deacetylase inhibition decreases proliferation and potentiates the effect of ionizing radiation in atypical teratoid/rhabdoid tumor cells

Atypical teratoid/rhabdoid tumor (ATRT) is a highly malignant central nervous system neoplasm that primarily occurs in children less than 3 years of age. Because of poor outcomes with intense and toxic multimodality treatment, new therapies are urgently needed. Histone deacetylase inhibitors (HDIs) have been evaluated as novel agents for multiple malignancies and have been shown to function as radiosensitizers. They act as epigenetic modifiers and lead to re-expression of inappropriately repressed genes, proteins, and cellular functions. Because of the underlying chromatin remodeling gene mutation in ATRT, HDIs are ideal candidates for therapeutic evaluation. To evaluate the role of HDIs against ATRT in vitro, we assessed the effect of drug treatment on proliferation, apoptosis, and gene expression. In addition, we examined HDI pretreatment as a radiosensitization strategy for ATRT. 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium with phenazine methosulfate electron coupling reagent (MTS) and clonogenic assays demonstrated that HDI treatment significantly reduces the proliferative capacity of BT-12 and BT-16 ATRT cells. In addition, the HDI SNDX-275 was able to induce apoptosis in both cell lines and induced p21(Waf1/Cip1) protein expression as measured by Western blot. Evaluation of differential gene expression by microarray and pathway analysis after HDI treatment demonstrated alterations of several key ATRT cellular functions. Finally, we showed that HDI pretreatment effectively potentiates the effect of ionizing radiation on ATRT cells as measured by clonogenic assay. Our findings suggest that the addition of HDIs to ATRT therapy may prove to be beneficial, especially when administered in combination with current treatment modalities, such as radiation.

A genomic approach to predict synergistic combinations for breast cancer treatment

We leverage genomic and biochemical data to identify synergistic drug regimens for breast cancer. In order to study the mechanism of the histone deacetylase (HDAC) inhibitors valproic acid (VPA) and suberoylanilide hydroxamic acid (SAHA) in breast cancer, we generated and validated genomic profiles of drug response using a series of breast cancer cell lines sensitive to each drug. These genomic profiles were then used to model drug response in human breast tumors and show significant correlation between VPA and SAHA response profiles in multiple breast tumor data sets, highlighting their similar mechanism of action. The genes deregulated by VPA and SAHA converge on the cell cycle pathway (Bayes factor 5.21 and 5.94, respectively; P-value 10(-8.6) and 10(-9), respectively). In particular, VPA and SAHA upregulate key cyclin-dependent kinase (CDK) inhibitors. In two independent datasets, cancer cells treated with CDK inhibitors have similar gene expression profile changes to the cellular response to HDAC inhibitors. Together, these results led us to hypothesize that VPA and SAHA may interact synergistically with CDK inhibitors such as PD-033299. Experiments show that HDAC and CDK inhibitors have statistically significant synergy in both breast cancer cell lines and primary 3-dimensional cultures of cells from pleural effusions of patients. Therefore, synergistic relationships between HDAC and CDK inhibitors may provide an effective combinatorial regimen for breast cancer. Importantly, these studies provide an example of how genomic analysis of drug-response profiles can be used to design rational drug combinations for cancer treatment.

Rhabdoid tumors of the liver: rare, aggressive, and poorly responsive to standard cytotoxic chemotherapy

BACKGROUND

Rhabdoid tumors of the liver are rare tumors that are difficult to cure. We compiled all the cases previously reported in the literature to review clinical data, treatments, and outcomes.

PROCEDURE

Patients were identified by literature review using PubMed.

RESULTS

Thirty-four patients were identified. The median age at presentation was 8 months. All patients with reported AFP results exhibited normal or minimally increased serum AFP levels. All 10 tumors with reported INI1 immunohistochemistry results were reported as negative. Twenty-one patients presented with metastatic disease at diagnosis. Thirty patients died of disease or treatment complications. Most deaths occurred within 12 months after diagnosis. Five patients survived at the time of the reports with one patient alive with disease. One patient relapsed and subsequently died after the report was published. Of the four patients alive without disease, all were treated with chemotherapy, and at least three had surgery or transplantation. Two patients received radiation therapy but did not survive.

CONCLUSIONS

Rhabdoid tumors of the liver are aggressive, rare tumors of the infant liver that are often associated with metastases at the time of diagnosis. Mortality is high and often occurs soon after diagnosis. Treatment with aggressive chemotherapy in combination (especially an alkylating agents doxorubicin) with complete resection may lead to improved outcomes. Therapy targeted to the INI1 mutation of these tumors is currently being investigated and may offer greater hope of cure.

p57(Kip2) and cancer: time for a critical appraisal

p57(Kip2) is a cyclin-dependent kinase inhibitor belonging to the Cip/Kip family, which also includes p21(Cip1) and p27(Kip1). So far, p57(Kip2) is the least-studied Cip/Kip protein, and for a long time its relevance has been related mainly to its unique role in embryogenesis. Moreover, genetic and molecular studies on animal models and patients with Beckwith-Wiedemann syndrome have shown that alterations in CDKN1C (the p57(Kip2) encoding gene) have functional relevance in the pathogenesis of this disease. Recently, a number of investigations have identified and characterized heretofore unexpected roles for p57(Kip2). The protein appears to be critically involved in initial steps of cell and tissue differentiation, and particularly in neuronal development and erythropoiesis. Intriguingly, p27(Kip1), the Cip/Kip member that is most homologous to p57(Kip2), is primarily involved in the process of cell cycle exit. p57(Kip2) also plays a critical role in controlling cytoskeletal organization and cell migration through its interaction with LIMK-1. Furthermore, p57(Kip2) appears to modulate genome expression. Finally, accumulating evidence indicates that p57(Kip2) protein is frequently downregulated in different types of human epithelial and nonepithelial cancers as a consequence of genetic and epigenetic events. In summary, the emerging picture is that several aspects of p57(Kip2)'s functions are only poorly clarified. This review represents an appraisal of the data available on the p57(Kip2) gene and protein structure, and its role in human physiology and pathology. We particularly focus our attention on p57(Kip2) changes in cancers and pharmacological approaches for modulating p57(Kip2) levels.

[Indications and current development of new targeted therapies in pediatric oncology]

Progresses performed in pediatric oncology during the last 30 years allowed to obtain about 70 to 80% healing rates. These progresses are the result of the optimization of the cytotoxic chemotherapies protocols used at standard and high doses, as well as the improvement of the local treatment. Most of the new anticancer treatments currently in developmental stage are based on targeted therapies, acting against numerous tumor cell abnormalities, like growth factors et their receptors, cell proliferation-inducing factors, molecules involved in DNA repair, cell death inducers, tumor invasion and angiogenesis. They are widely used in adult patients since 10 years and they are being more and more employed in children with cancer. The aim of this article is to review the main indications of these new targeted drugs in pediatric oncology and the new developments of these drugs.

The hallmarks of CDKN1C (p57, KIP2) in cancer

Cyclin-dependent kinase inhibitor 1C CDKN1C (p57(KIP2)) regulates several hallmarks of cancer, including apoptosis, cell invasion and metastasis, tumor differentiation and angiogenesis. p57(KIP2) is generally not mutated in cancer, but its expression is downregulated through epigenetic changes such as DNA methylation and repressive histone marks at the promoter. This opens up possibilities for therapeutic intervention through reactivation of p57(KIP2) gene expression. Furthermore, p57(KIP2) has been tested as a prognostic factor for many types of cancer, even differentiating between early and late stage cancer. In this review, the multifunctional tumor suppressor capabilities of p57(KIP2), the mechanisms of p57(KIP2) transcriptional repression in cancer, and the therapeutic potential of reactivation of p57(KIP2) protein expression will be discussed.

Rhabdoid tumor: gene expression clues to pathogenesis and potential therapeutic targets

Rhabdoid tumors (RT) are aggressive tumors characterized by genetic loss of SMARCB1 (SNF5, INI-1), a component of the SWI/SNF chromatin remodeling complex. No effective treatment is currently available. This study seeks to shed light on the SMARCB1-mediated pathogenesis of RT and to discover potential therapeutic targets. Global gene expression of 10 RT was compared with 12 cellular mesoblastic nephromas, 16 clear cell sarcomas of the kidney, and 15 Wilms tumors. In all, 114 top genes were differentially expressed in RT (P<0.001, fold change >2 or <0.5). Among these were downregulation of SMARCB1 and genes previously associated with SMARCB1 (ATP1B1, PTN, DOCK4, NQO1, PLOD1, PTP4A2, PTPRK); 28/114 top differentially expressed genes were involved with neural or neural crest development and were all sharply downregulated. This was confirmed by Gene Set Enrichment Analysis (GSEA). Neural and neural crest stem cell marker proteins SOX10, ID3, CD133, and Musashi were negative by immunohistochemistry, whereas Nestin was positive. Decreased expression of CDKN1A, CDKN1B, CDKN1C, CDKN2A, and CCND1 was identified, while MYC-C was upregulated. GSEA of independent gene sets associated with bivalent histone modification and polycomb group targets in embryonic stem cells showed significant negative enrichment in RT. Several differentially expressed genes were associated with tumor suppression, invasion, and metastasis, including SPP1 (osteopontin), COL18A1 (endostatin), PTPRK, and DOCK4. We conclude that RTs arise within early progenitor cells during a critical developmental window in which loss of SMARCB1 directly results in repression of neural development, loss of cyclin-dependent kinase inhibition, and trithorax/polycomb dysregulation.

A G-CSF-secreting adrenal carcinoma with rhabdoid-like differentiation causing leukocytosis

BACKGROUND

A 57-year-old African American man presented to a tertiary care center with a 6-month history of fatigue and worsening abdominal pain. He had lost 9.1 kg in weight in the 3 months leading up to presentation, and described subjective fevers and night sweats for 1 month with a nonproductive cough and blurred vision for several weeks before presentation. He had chronic renal insufficiency, sleep apnea, hypertension, and peripheral vascular disease.

INVESTIGATIONS

Physical examination, complete blood count, peripheral blood smear, leukocyte alkaline phosphatase score, bone marrow biopsy, CT of the chest, abdomen, and pelvis, MRI of the abdomen and pelvis, measurement of plasma and urine metanephrines, 24 h urine testing for cortisol and 17-ketosteroids, measurement of serum granulocyte colony-stimulating factor (G-CSF) level, histopathologic examination and immunohistochemical staining of resected tumor.

DIAGNOSIS

G-CSF-secreting adrenal carcinoma with rhabdoid-like differentiation.

MANAGEMENT

En bloc surgical resection of kidney, suprarenal mass and spleen was performed, followed by initiation of mitotane chemotherapy 3 months later.

p57KIP2: "Kip"ing the cell under control

p57(KIP2) is an imprinted gene located at the chromosomal locus 11p15.5. It is a cyclin-dependent kinase inhibitor belonging to the CIP/KIP family, which includes additionally p21(CIP1/WAF1) and p27(KIP1). It is the least studied CIP/KIP member and has a unique role in embryogenesis. p57(KIP2) regulates the cell cycle, although novel functions have been attributed to this protein including cytoskeletal organization. Molecular analysis of animal models and patients with Beckwith-Wiedemann Syndrome have shown its nodal implication in the pathogenesis of this syndrome. p57(KIP2) is frequently down-regulated in many common human malignancies through several mechanisms, denoting its anti-oncogenic function. This review is a thorough analysis of data available on p57(KIP2), in relation to p21(CIP1/WAF1) and p27(KIP1), on gene and protein structure, its transcriptional and translational regulation, and its role in human physiology and pathology, focusing on cancer development.

Analysis of chromosomal aberration (1, 3, and 8) and association of microRNAs in uveal melanoma

PURPOSE

Uveal melanoma is the most common intraocular primary tumor, involving iris, ciliary body and choroid. More than 90% of the patients develop hepatic metastasis with an average survival time of 7 months. We have used formalin fixed paraffin embedded sections to validate the presence of monosomy 3, an accurate predictor of metastasis, chromosome 8 isochromosome (8q22), and 1p36 deletion. This study also tested the presence of oncomirs in uveal melanoma samples by microRNA (miRNA) expression profiling.

METHODS

Chromogenic in situ hybridization (CISH) was performed in formalin fixed, paraffin embedded sections of uveal melanoma to analyze chromosome 1, 3, and 8 aberrations (n=60). MicroRNA (miRNA) expression profiling was done on paraffin sections of invasive tumor with liver metastasis (n=1) and non invasive tumor (n=1) in biological duplicates. Samples for miRNA expression profiling were identified based on case registry and the harboring of monosomy 3 by CISH.

RESULTS

A significant correlation (p=0.05) between metastasizing and non-metastasizing melanoma harboring chromosomal aberrations- monosomy3, c-myc, and 1p36 was observed by Pearson's correlation. A significant correlation was observed in monosomy 3 and 1p36 positive cases in the tumor samples (p=0.039). No significance was observed between monosomy 3 and c-myc positive cases. No significance (p=0.096) was observed between c-myc amplification and trisomy (extra whole chromosome 8). MicroRNA expression profiling revealed the presence of 19 miRNAs expressed in non-metastasizing melanoma and absent in metastasizing melanoma. Eleven miRNAs were found to be expressed in metastasizing melanoma and absent in non-metastasizing melanoma. Genes targeted by the miRNAs were found to be present in chromosomal regions 8p22, 13q, and 17p but were often found to be deleted.

CONCLUSIONS

This technique can be applied to routine pathology using archival specimens to identify patients with monosomy 3. We were able to perform CISH in all the cases except the heavily pigmented tumors, where dots were observed but were not assessed. Initial studies on microRNA have revealed their role as oncomirs in both metastasizing and non-metastasizing melanomas. Further studies may provide insights into their role in tumor progression and facilitate metastatic phenotype analysis.