NBN

Gene Summary

Gene:NBN; nibrin
Aliases: ATV, NBS, P95, NBS1, AT-V1, AT-V2
Location:8q21
Summary:Mutations in this gene are associated with Nijmegen breakage syndrome, an autosomal recessive chromosomal instability syndrome characterized by microcephaly, growth retardation, immunodeficiency, and cancer predisposition. The encoded protein is a member of the MRE11/RAD50 double-strand break repair complex which consists of 5 proteins. This gene product is thought to be involved in DNA double-strand break repair and DNA damage-induced checkpoint activation. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:nibrin
HPRD
Source:NCBIAccessed: 27 February, 2015

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 27 February 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Wilms Tumour
  • Protein Structure, Tertiary
  • Sequence Deletion
  • Adolescents
  • T-Lymphocytes
  • Rabbits
  • Cervical Cancer
  • Germ-Line Mutation
  • Genetic Recombination
  • DNA Sequence Analysis
  • Risk Factors
  • Slovakia
  • Heterozygote
  • Genotype
  • Telomere
  • DNA Damage
  • Genetic Predisposition
  • Protein-Serine-Threonine Kinases
  • DNA-Binding Proteins
  • Telomere-Binding Proteins
  • Prostate Cancer
  • Polymorphism
  • Chromosome 8
  • Breast Cancer
  • DNA Repair
  • Stomach Cancer
  • Tumor Suppressor Proteins
  • Risk Assessment
  • Messenger RNA
  • DNA Mutational Analysis
  • Ovarian Cancer
  • Ataxia Telangiectasia Mutated Proteins
  • Sensitivity and Specificity
  • cdc25 Phosphatases
  • Mutation
  • Cell Cycle Proteins
  • beta-Galactosidase
  • Sequence Homology
  • DNA Repair Enzymes
  • Case-Control Studies
Tag cloud generated 27 February, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: NBN (cancer-related)

Landau DA, Clement K, Ziller MJ, et al.
Locally disordered methylation forms the basis of intratumor methylome variation in chronic lymphocytic leukemia.
Cancer Cell. 2014; 26(6):813-25 [PubMed] Article available free on PMC after 08/12/2015 Related Publications
Intratumoral heterogeneity plays a critical role in tumor evolution. To define the contribution of DNA methylation to heterogeneity within tumors, we performed genome-scale bisulfite sequencing of 104 primary chronic lymphocytic leukemias (CLLs). Compared with 26 normal B cell samples, CLLs consistently displayed higher intrasample variability of DNA methylation patterns across the genome, which appears to arise from stochastically disordered methylation in malignant cells. Transcriptome analysis of bulk and single CLL cells revealed that methylation disorder was linked to low-level expression. Disordered methylation was further associated with adverse clinical outcome. We therefore propose that disordered methylation plays a similar role to that of genetic instability, enhancing the ability of cancer cells to search for superior evolutionary trajectories.

Lee W, Teckie S, Wiesner T, et al.
PRC2 is recurrently inactivated through EED or SUZ12 loss in malignant peripheral nerve sheath tumors.
Nat Genet. 2014; 46(11):1227-32 [PubMed] Article available free on PMC after 01/05/2015 Related Publications
Malignant peripheral nerve sheath tumors (MPNSTs) represent a group of highly aggressive soft-tissue sarcomas that may occur sporadically, in association with neurofibromatosis type I (NF1 associated) or after radiotherapy. Using comprehensive genomic approaches, we identified loss-of-function somatic alterations of the Polycomb repressive complex 2 (PRC2) components (EED or SUZ12) in 92% of sporadic, 70% of NF1-associated and 90% of radiotherapy-associated MPNSTs. MPNSTs with PRC2 loss showed complete loss of trimethylation at lysine 27 of histone H3 (H3K27me3) and aberrant transcriptional activation of multiple PRC2-repressed homeobox master regulators and their regulated developmental pathways. Introduction of the lost PRC2 component in a PRC2-deficient MPNST cell line restored H3K27me3 levels and decreased cell growth. Additionally, we identified frequent somatic alterations of CDKN2A (81% of all MPNSTs) and NF1 (72% of non-NF1-associated MPNSTs), both of which significantly co-occur with PRC2 alterations. The highly recurrent and specific inactivation of PRC2 components, NF1 and CDKN2A highlights their critical and potentially cooperative roles in MPNST pathogenesis.

Nikiforov YE, Carty SE, Chiosea SI, et al.
Highly accurate diagnosis of cancer in thyroid nodules with follicular neoplasm/suspicious for a follicular neoplasm cytology by ThyroSeq v2 next-generation sequencing assay.
Cancer. 2014; 120(23):3627-34 [PubMed] Related Publications
BACKGROUND: Fine-needle aspiration (FNA) cytology is a common approach to evaluating thyroid nodules, although 20% to 30% of FNAs have indeterminate cytology, which hampers the appropriate management of these patients. Follicular (or oncocytic) neoplasm/suspicious for a follicular (or oncocytic) neoplasm (FN/SFN) is a common indeterminate diagnosis with a cancer risk of approximately 15% to 30%. In this study, the authors tested whether the most complete next-generation sequencing (NGS) panel of genetic markers could significantly improve cancer diagnosis in these nodules.
METHODS: The evaluation of 143 consecutive FNA samples with a cytologic diagnosis of FN/SFN from patients with known surgical outcomes included 91 retrospective samples and 52 prospective samples. Analyses were performed on a proprietary sequencer using the targeted ThyroSeq v2 NGS panel, which simultaneously tests for point mutations in 13 genes and for 42 types of gene fusions that occur in thyroid cancer. The expression of 8 genes was used to assess the cellular composition of FNA samples.
RESULTS: In the entire cohort, histologic analysis revealed 104 benign nodules and 39 malignant nodules. The most common point mutations involved the neuroblastoma RAS viral oncogene homolog (NRAS), followed by the Kirsten rat sarcoma viral oncogene homolog (KRAS), the telomerase reverse transcriptase (TERT) gene, and the thyroid-stimulating hormone receptor (TSHR) gene. The identified fusions involved the thyroid adenoma associated (THADA) gene; the peroxisome proliferator-activated receptor γ (PPARG) gene; and the neurotrophic tyrosine kinase, receptor, type 3 (NTRK3) gene. Performance characteristics were similar in the retrospective and prospective groups. Among all FN/SFN nodules, preoperative ThyroSeq v2 performed with 90% sensitivity (95% confidence interval [CI], 80%-99%), 93% specificity (95% CI, 88%-98%), a positive predictive value of 83% (95% CI, 72%-95%), a negative predictive value of 96% (95% CI, 92%-100%), and 92% accuracy (95% CI, 88%-97%).
CONCLUSIONS: The current results indicate that comprehensive genotyping of thyroid nodules using a broad NGS panel provides a highly accurate diagnosis for nodules with FN/SFN cytology and should facilitate the optimal management of these patients.

Lee CS, Bhaduri A, Mah A, et al.
Recurrent point mutations in the kinetochore gene KNSTRN in cutaneous squamous cell carcinoma.
Nat Genet. 2014; 46(10):1060-2 [PubMed] Article available free on PMC after 01/05/2015 Related Publications
Here we report the discovery of recurrent mutations concentrated at an ultraviolet signature hotspot in KNSTRN, which encodes a kinetochore protein, in 19% of cutaneous squamous cell carcinomas (SCCs). Cancer-associated KNSTRN mutations, most notably those encoding p.Ser24Phe, disrupt chromatid cohesion in normal cells, occur in SCC precursors, correlate with increased aneuploidy in primary tumors and enhance tumorigenesis in vivo. These findings suggest a role for KNSTRN mutagenesis in SCC development.

Cantara S, Pilli T, Sebastiani G, et al.
Circulating miRNA95 and miRNA190 are sensitive markers for the differential diagnosis of thyroid nodules in a Caucasian population.
J Clin Endocrinol Metab. 2014; 99(11):4190-8 [PubMed] Related Publications
CONTEXT: MicroRNA (miRNAs) are nonprotein-encoding RNAs that regulate gene expression and enable the distinction of benign from malignant tissues in human cancers.
OBJECTIVE: We investigated the role of miRNA circulating in the blood for the differential diagnosis of thyroid nodules.
SETTING AND DESIGN: miRNA profiling was assessed by TaqMan Array Human MicroRNA A Cards v2.0 in pooled sera from 12 healthy subjects (HS), 12 nodular goiters (NG), and 12 patients with papillary thyroid cancer (PTC) (cohort 1). From this analysis, we selected eight miRNAs that were validated in individual samples (same of cohort 1) by qRT-PCR. Four miRNAs were confirmed differentially expressed in PTC and were analyzed in a larger second cohort.
RESULTS: The profiling analysis revealed eight miRNAs (miRNA579, -95, -29b, 5-01-3p, -548d-5p down-regulated, and miR190, -362-3p, -518a-5p up-regulated) which differ in PTC compared with NG and HS. After the validation in individual samples, we confirmed as differentially expressed miRNA579, -95, -29b, and miRNA190. These miRNAs were further validated in a second cohort of sera from 79 PTC, 80 NG, and 41 HS. MiRNA95 had a sensitivity of 94.9%, which reached 100% in a multivariate risk model combined with miRNA190. We developed a mathematical formula that calculates the probability of malignancy with a cut-off value of 0.5 above which the patient was at high risk of malignancy.
CONCLUSIONS: We have identified for the first time two miRNAs differently expressed in serum of PTC patients who in combination allow the differential diagnosis of thyroid nodules with great accuracy in our study population. Additional studies are required; however, to define whether these results will also be generalized across other patient populations."

Christensen LL, Holm A, Rantala J, et al.
Functional screening identifies miRNAs influencing apoptosis and proliferation in colorectal cancer.
PLoS One. 2014; 9(6):e96767 [PubMed] Article available free on PMC after 01/05/2015 Related Publications
MicroRNAs (miRNAs) play a critical role in many biological processes and are aberrantly expressed in human cancers. Particular miRNAs function either as tumor suppressors or oncogenes and appear to have diagnostic and prognostic significance. Although numerous miRNAs are dys-regulated in colorectal cancer (CRC) only a small fraction has been characterized functionally. Using high-throughput functional screening and miRNA profiling of clinical samples the present study aims at identifying miRNAs important for the control of cellular growth and/or apoptosis in CRC. The high-throughput functional screening was carried out in six CRC cell lines transfected with a pre-miR library including 319 synthetic human pre-miRs. Phenotypic alterations were evaluated by immunostaining of cleaved cPARP (apoptosis) or MKI67 (proliferation). Additionally, TaqMan Human MicroRNA Array Set v2.0 was used to profile the expression of 667 miRNAs in 14 normal colon mucosa and 46 microsatellite stable stage II CRC patients. Among the miRNAs that induced growth arrest and apoptosis in the CRC cell lines, and at same time were dys-regulated in the clinical samples, miR-375 was selected for further analysis. Independent in vitro analysis of transient and stable transfected CRC cell lines confirmed that miR-375 reduces cell viability through the induction of apoptotic death. We identified YAP1 as a direct miR-375 target in CRC and show that HELLS and NOLC1 are down-stream targets. Knock-down of YAP1 mimicked the phenotype induced by miR-375 over-expression indicating that miR-375 most likely exerts its pro-apoptotic role through YAP1 and its anti-apoptotic down-stream targets BIRC5 and BCL2L1. Finally, in vivo analysis of mouse xenograft tumors showed that miR-375 expression significantly reduced tumor growth. We conclude that the high-throughput screening successfully identified miRNAs that induce apoptosis and/or inhibit proliferation in CRC cells. Finally, combining the functional screening with profiling of CRC tissue samples we identified clinically relevant miRNAs and miRNA targets in CRC.

Silva FC, Lisboa BC, Figueiredo MC, et al.
Hereditary breast and ovarian cancer: assessment of point mutations and copy number variations in Brazilian patients.
BMC Med Genet. 2014; 15:55 [PubMed] Article available free on PMC after 01/05/2015 Related Publications
BACKGROUND: Germ line mutations in BRCA1 and BRCA2 (BRCA1/2) and other susceptibility genes have been identified as genetic causes of hereditary breast and ovarian cancer (HBOC). To identify the disease-causing mutations in a cohort of 120 Brazilian women fulfilling criteria for HBOC, we carried out a comprehensive screening of BRCA1/2, TP53 R337H, CHEK2 1100delC, followed by an analysis of copy number variations in 14 additional breast cancer susceptibility genes (PTEN, ATM, NBN, RAD50, RAD51, BRIP1, PALB2, MLH1, MSH2, MSH6, TP53, CDKN2A, CDH1 and CTNNB1).
METHODS: Capillary sequencing and multiplex ligation-dependent probe amplification (MLPA) were used for detecting point mutations and copy number variations (CNVs), respectively, for the BRCA1 and BRCA2 genes; capillary sequencing was used for point mutation for both variants TP53 R337H and CHEK2 1100delC, and finally array comparative genomic hybridization (array-CGH) was used for identifying CNVs in the 14 additional genes.
RESULTS: The positive detection rate in our series was 26%. BRCA1 pathogenic mutations were found in 20 cases, including two cases with CNVs, whereas BRCA2 mutations were found in 7 cases. We also found three patients with the TP53 R337H mutation and one patient with the CHEK2 1100delC mutation. Seven (25%) pathogenic mutations in BRCA1/2 were firstly described, including a splice-site BRCA1 mutation for which pathogenicity was confirmed by the presence of an aberrant transcript showing the loss of the last 62 bp of exon 7. Microdeletions of exon 4 in ATM and exon 2 in PTEN were identified in BRCA2-mutated and BRCA1/2-negative patients, respectively.
CONCLUSIONS: In summary, our results showed a high frequency of BRCA1/2 mutations and a higher prevalence of BRCA1 (64.5%) gene. Moreover, the detection of the TP53 R337H variant in our series and the fact that this variant has a founder effect in our population prompted us to suggest that all female breast cancer patients with clinical criteria for HBOC and negative for BRCA1/2 genes should be tested for the TP53 R337H variant. Furthermore, the presence of genomic structural rearrangement resulting in CNVs in other genes that predispose breast cancer in conjunction with BRCA2 point mutations demonstrated a highly complex genetic etiology in Brazilian breast cancer families.

Liu X, Mody K, de Abreu FB, et al.
Molecular profiling of appendiceal epithelial tumors using massively parallel sequencing to identify somatic mutations.
Clin Chem. 2014; 60(7):1004-11 [PubMed] Related Publications
BACKGROUND: Some epithelial neoplasms of the appendix, including low-grade appendiceal mucinous neoplasm and adenocarcinoma, can result in pseudomyxoma peritonei (PMP). Little is known about the mutational spectra of these tumor types and whether mutations may be of clinical significance with respect to therapeutic selection. In this study, we identified somatic mutations using the Ion Torrent AmpliSeq Cancer Hotspot Panel v2.
METHODS: Specimens consisted of 3 nonneoplastic retention cysts/mucocele, 15 low-grade mucinous neoplasms (LAMNs), 8 low-grade/well-differentiated mucinous adenocarcinomas with pseudomyxoma peritonei, and 12 adenocarcinomas with/without goblet cell/signet ring cell features. Barcoded libraries were prepared from up to 10 ng of extracted DNA and multiplexed on single 318 chips for sequencing. Data analysis was performed using Golden Helix SVS. Variants that remained after the analysis pipeline were individually interrogated using the Integrative Genomics Viewer.
RESULTS: A single Janus kinase 3 (JAK3) mutation was detected in the mucocele group. Eight mutations were identified in the V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) and GNAS complex locus (GNAS) genes among LAMN samples. Additional gene mutations were identified in the AKT1 (v-akt murine thymoma viral oncogene homolog 1), APC (adenomatous polyposis coli), JAK3, MET (met proto-oncogene), phosphatidylinositol-4,5-bisphosphate 3-kinase (PIK3CA), RB1 (retinoblastoma 1), STK11 (serine/threonine kinase 11), and tumor protein p53 (TP53) genes. Among the PMPs, 6 mutations were detected in the KRAS gene and also in the GNAS, TP53, and RB1 genes. Appendiceal cancers showed mutations in the APC, ATM (ataxia telangiectasia mutated), KRAS, IDH1 [isocitrate dehydrogenase 1 (NADP+)], NRAS [neuroblastoma RAS viral (v-ras) oncogene homolog], PIK3CA, SMAD4 (SMAD family member 4), and TP53 genes.
CONCLUSIONS: Our results suggest molecular heterogeneity among epithelial tumors of the appendix. Next generation sequencing efforts have identified mutational spectra in several subtypes of these tumors that may suggest a phenotypic heterogeneity showing mutations that are relevant for targeted therapies.

Ong CA, Shannon NB, Ross-Innes CS, et al.
Amplification of TRIM44: pairing a prognostic target with potential therapeutic strategy.
J Natl Cancer Inst. 2014; 106(5) [PubMed] Article available free on PMC after 01/05/2015 Related Publications
BACKGROUND: Many prognostic biomarkers have been proposed recently. However, there is a lack of therapeutic strategies exploiting novel prognostic biomarkers. We aimed to propose therapeutic options in patients with overexpression of TRIM44, a recently identified prognostic gene.
METHODS: Genomic and transcriptomic data of epithelial cancers (n = 1932), breast cancers (BCs; n = 1980) and esophago-gastric cancers (EGCs; n = 163) were used to identify genomic aberrations driving TRIM44 overexpression. The driver gene status of TRIM44 was determined using a small interfering RNA (siRNA) screen of the 11p13 amplicon. Integrative analysis was applied across multiple datasets to identify pathway activation and potential therapeutic strategies. Validation of the in silico findings were performed using in vitro assays, xenografts, and patient samples (n = 160).
RESULTS: TRIM44 overexpression results from genomic amplification in 16.1% of epithelial cancers, including 8.1% of EGCs and 6.1% of BCs. This was confirmed using fluorescent in situ hybridization. The siRNA screen confirmed TRIM44 to be a driver of the amplicon. In silico analysis revealed an association between TRIM44 and mTOR signalling, supported by a decrease in mTOR signalling after siRNA knockdown of TRIM44 in cell lines and colocalization of TRIM44 and p-mTOR in patient samples. In vitro inhibition studies using an mTOR inhibitor (everolimus) decreased cell viability in two TRIM44-amplified cells lines by 88% and 70% compared with 35% in the control cell line. These findings were recapitulated in xenograft models.
CONCLUSIONS: Genomic amplification drives TRIM44 overexpression in EGCs and BCs. Targeting the mTOR pathway provides a potential therapeutic option for TRIM44-amplified tumors.

Wang Y, Gao S, Liu G, et al.
Microarray expression profile analysis of long non-coding RNAs in human gastric cardiac adenocarcinoma.
Cell Physiol Biochem. 2014; 33(4):1225-38 [PubMed] Related Publications
BACKGROUND/AIMS: Long noncoding RNAs (lncRNAs) are pervasively transcribed and have been shown to regulate key biological processes that maintain normal cellular functions. Abnormal regulation of these lncRNAs can promote tumorigenesis through resulting aberrant cellular essential functions. however, the roles of lncRNAs played in the development of gastric cardiac adenocarcinoma (GCA) remain unknown. With this work we aimed to show the expression profile of lncRNAs in GCA tissues compared with paired adjacent noncancerous tissue using microarray analysis in order to interrogate potential carcinogenesis molecular mechanisms of GCA from lncRNA level.
METHODS: In this study, total RNA was isolated from 15 pairs of GCA tissue, cancerous and non-cancerous, and hybridized to arraystar lncRNA V2.0 chips containing probes representing 33,000 lncRNA genes. Quantitative real-time polymerase chain reaction (PCR) was used to validate 6 up-regulated and 6 down-regulated lncRNAs. Bioinformatic analysis including gene ontology(GO) analysis, pathway analysis and network analysis was done for further investigation.
RESULTS: Pathway analysis indicated that 8 pathways corresponded to downregulated transcripts and that 20 pathways corresponded to up-regulated transcripts (p-value cut-off is 0.05). GO analysis showed that the highest enriched GOs targeted by up-regulated transcripts were tissue homeostasis and the highest esenriched GOs targeted by the downregulated transcripts were tissue homeostasis.
CONCLUSION: Our study is the first to interrogate differentially expressed lncRNAs in human GCA tissues and indicates that lncRNAs may be used as novel candidate biomarkers for the clinical diagnosis of GCA and potential targets for further therapy.

Yin T, Wang P, Li J, et al.
Tumor-penetrating codelivery of siRNA and paclitaxel with ultrasound-responsive nanobubbles hetero-assembled from polymeric micelles and liposomes.
Biomaterials. 2014; 35(22):5932-43 [PubMed] Related Publications
Drug resistance is a big problem in systemic chemotherapy of hepatocellular carcinoma (HCC), and nanomedicines loaded with both chemotherapeutic agents (e.g. paclitaxel, PTX) and siRNA's targeting antiapoptosis genes (e.g. BCL-2) possess the advantages to simultaneously overcome the efflux pump-mediated drug resistance and antiapoptosis-related drug resistance. However, tumor-penetrating drug delivery with this type of nanomedicines is extremely difficult due to their relatively big size compared to the single drug-loaded nanomedicines. Aiming at address this problem, US-responsive nanobubbles encapsulating both anti-cancer drug paclitaxel (PTX) and siRNA (PTX-NBs/siRNA) for HCC treatment were developed by hetero-assembly of polymeric micelles and liposomes in the present study. Utilizing an external low-frequency US force imposed to the tumor site, effective tumor-penetrating codelivery of siRNA and PTX was achieved via tail vein injection of PTX-NBs/siRNA into nude mice bearing human HepG2 xerografts. Consequently, the PTX treatment-inducible antiapoptosis in HepG2 cells was effectively suppressed by the codelivered siRNA targeting an antiapoptosis gene (BCL-2 siRNA) during chemotherapy. Owing to the synergistic anti-cancer effect of two therapeutic agents, tumor growth was completely inhibited using low-dose PTX in animal study. Our results highlight the great potential of this type of US-responsive hetero-assemblies carrying both anti-cancer drug and siRNA as an effective nanomedicinal system for HCC therapy.

Molina-Pinelo S, Pastor MD, Suarez R, et al.
MicroRNA clusters: dysregulation in lung adenocarcinoma and COPD.
Eur Respir J. 2014; 43(6):1740-9 [PubMed] Related Publications
Lung adenocarcinoma and chronic obstructive pulmonary disease (COPD) are pulmonary diseases that share common aetiological factors (tobacco smoking) and probable dysregulated pathways. MicroRNAs (miRNAs) play an essential role in regulating numerous physiological and pathological processes. The purpose of this study was to assess global miRNA expression patterns in patients with COPD and/or adenocarcinoma to elucidate distinct regulatory networks involved in the pathogenesis of these two smoking-related diseases. Expression of 381 miRNAs was quantified by TaqMan Human MicroRNA A Array v2.0 in bronchoalveolar lavage fluid samples from 87 patients classified into four groups: COPD, adenocarcinoma, adenocarcinoma with COPD, and control (neither COPD nor adenocarcinoma). 11 differentially expressed miRNAs were randomly selected for validation in an independent cohort of 40 patients. Distinct miRNA expression profiles were identified and validated for each pathological group, involving 66 differentially expressed miRNAs. Four miRNA clusters (the mir-17-92 cluster and its paralogues, mir-106a-363 and mir-106b-25; and the miR-192-194 cluster) were upregulated in patients with adenocarcinoma and one miRNA cluster (miR-132-212) was upregulated in patients with COPD. These results contribute to unravelling miRNA-controlled networks involved in the pathogenesis of adenocarcinoma and COPD, and provide new tools of potential use as biomarkers for diagnosis and/or therapeutic purposes.

Ruggeri P, Farina AR, Di Ianni N, et al.
The TrkAIII oncoprotein inhibits mitochondrial free radical ROS-induced death of SH-SY5Y neuroblastoma cells by augmenting SOD2 expression and activity at the mitochondria, within the context of a tumour stem cell-like phenotype.
PLoS One. 2014; 9(4):e94568 [PubMed] Article available free on PMC after 01/05/2015 Related Publications
The developmental and stress-regulated alternative TrkAIII splice variant of the NGF receptor TrkA is expressed by advanced stage human neuroblastomas (NBs), correlates with worse outcome in high TrkA expressing unfavourable tumours and exhibits oncogenic activity in NB models. In the present study, we report that constitutive TrkAIII expression in human SH-SY5Y NB cells inhibits Rotenone, Paraquat and LY83583-induced mitochondrial free radical reactive oxygen species (ROS)-mediated death by stimulating SOD2 expression, increasing mitochondrial SOD2 activity and attenuating mitochondrial free radical ROS production, in association with increased mitochondrial capacity to produce H2O2, within the context of a more tumour stem cell-like phenotype. This effect can be reversed by the specific TrkA tyrosine kinase inhibitor GW441756, by the multi-kinase TrkA inhibitors K252a, CEP-701 and Gö6976, which inhibit SOD2 expression, and by siRNA knockdown of SOD2 expression, which restores the sensitivity of TrkAIII expressing SH-SY5Y cells to Rotenone, Paraquat and LY83583-induced mitochondrial free radical ROS production and ROS-mediated death. The data implicate the novel TrkAIII/SOD2 axis in promoting NB resistance to mitochondrial free radical-mediated death and staminality, and suggest that the combined use of TrkAIII and/or SOD2 inhibitors together with agents that induce mitochondrial free radical ROS-mediated death could provide a therapeutic advantage that may also target the stem cell niche in high TrkA expressing unfavourable NB.

Kurian AW, Hare EE, Mills MA, et al.
Clinical evaluation of a multiple-gene sequencing panel for hereditary cancer risk assessment.
J Clin Oncol. 2014; 32(19):2001-9 [PubMed] Article available free on PMC after 01/07/2015 Related Publications
PURPOSE: Multiple-gene sequencing is entering practice, but its clinical value is unknown. We evaluated the performance of a customized germline-DNA sequencing panel for cancer-risk assessment in a representative clinical sample.
METHODS: Patients referred for clinical BRCA1/2 testing from 2002 to 2012 were invited to donate a research blood sample. Samples were frozen at -80° C, and DNA was extracted from them after 1 to 10 years. The entire coding region, exon-intron boundaries, and all known pathogenic variants in other regions were sequenced for 42 genes that had cancer risk associations. Potentially actionable results were disclosed to participants.
RESULTS: In total, 198 women participated in the study: 174 had breast cancer and 57 carried germline BRCA1/2 mutations. BRCA1/2 analysis was fully concordant with prior testing. Sixteen pathogenic variants were identified in ATM, BLM, CDH1, CDKN2A, MUTYH, MLH1, NBN, PRSS1, and SLX4 among 141 women without BRCA1/2 mutations. Fourteen participants carried 15 pathogenic variants, warranting a possible change in care; they were invited for targeted screening recommendations, enabling early detection and removal of a tubular adenoma by colonoscopy. Participants carried an average of 2.1 variants of uncertain significance among 42 genes.
CONCLUSION: Among women testing negative for BRCA1/2 mutations, multiple-gene sequencing identified 16 potentially pathogenic mutations in other genes (11.4%; 95% CI, 7.0% to 17.7%), of which 15 (10.6%; 95% CI, 6.5% to 16.9%) prompted consideration of a change in care, enabling early detection of a precancerous colon polyp. Additional studies are required to quantify the penetrance of identified mutations and determine clinical utility. However, these results suggest that multiple-gene sequencing may benefit appropriately selected patients.

Li J, Zou WX, Chang KS
Inhibition of Sp1 functions by its sequestration into PML nuclear bodies.
PLoS One. 2014; 9(4):e94450 [PubMed] Article available free on PMC after 01/07/2015 Related Publications
Promyelocytic leukemia nuclear bodies (PML NBs) are comprised of PML and a striking variety of its associated proteins. Various cellular functions have been attributed to PML NBs, including the regulation of gene expression. We report here that induced expression of PML recruits Sp1 into PML NBs, leading to the reduction of Sp1 transactivation function. Specifically, Chromatin immunoprecipitation (ChIP) assay demonstrated that induced expression of PML significantly diminishes the amount of Sp1 binding to its target gene promoter, immunofluorescence staining showed dramatic increase in the co-localization between PML and Sp1 upon induction of PML expression, moreover, PML and Sp1 co-fractionated in the core nuclear matrix. Our study further showed that PML promotes SUMOylation of Sp1 in a RING-motif-dependent manner, SUMOylation of Sp1 facilitates physical interaction between Sp1 and PML and recruitment of Sp1 into the PML NBs, the SUMO binding motif of PML was also important for its interaction with Sp1. The results of this study demonstrate a novel mechanism by which PML regulates gene expression through sequestration of the transcription factor into PML NBs.

Jiang YH, Xu XL, Ruan HH, et al.
The impact of functional LIG4 polymorphism on platinum-based chemotherapy response and survival in non-small cell lung cancer.
Med Oncol. 2014; 31(5):959 [PubMed] Related Publications
DNA repair capacity is correlated with the sensitivity of cancer cells toward platinum-based chemotherapy. The aim of this study was to investigate whether single-nucleotide polymorphisms (SNPs) in DNA repair genes NBS1, LIG4, and RAD51 were correlated with tumor response in advanced non-small cell lung cancer (NSCLC) patients in a Chinese population who received platinum-based chemotherapy. The treatment outcomes of 146 advanced NSCLC patients who were treated with platinum-based chemotherapy were evaluated. The polymorphic status of three SNPs was determined by genotyping via the polymerase chain reaction-restriction fragment length polymorphism method. Forty-five patients in the group with the CC genotype (45/90) showed a good response to treatment, while only 18 patients in the CT+TT group (18/55) showed a good response, indicating a substantial differences in the chemotherapy response rate based on the LIG4 Thr9Ile polymorphism (P = 0.042). Patients with the GG genotype for the NSB1 Glu185Gln polymorphism were more sensitive to platinum-based chemotherapy compared with patients with either the CG or CC genotype (P = 0.001). Kaplan-Meier analysis of all patients showed a significant association between the LIG4 Thr9Ile CC polymorphism and superior progression-free survival and overall survival (log-rank P = 0.045 and 0.031, respectively). However, there were no significant differences in survival based on the LIG4 Thr9Ile or the RAD51 135G>C polymorphisms. Polymorphisms in the NSB1 and LIG4 genes may be a predictive marker for treatment response and for advanced NSCLC patients in stage IIIB + IV. The CC genotype of the LIG4 Thr9Ile polymorphism may also serve as an independent prognosis factor.

Zhang H, Nan X, Li X, et al.
CMTM5 exhibits tumor suppressor activity through promoter methylation in oral squamous cell carcinoma.
Biochem Biophys Res Commun. 2014; 447(2):304-10 [PubMed] Related Publications
Oral squamous cell carcinoma (OSCC) is one of the most common types of malignancies in the head and neck region. CKLF-like MARVEL transmembrane domain-containing member 5 (CMTM5) has been recently implicated as a tumor suppressor gene in several cancer types. Herein, we examined the expression and function of CMTM5 in oral squamous cell carcinoma. CMTM5 was down-regulated in oral squamous cell lines and tumor samples from patients with promoter methylation. Treatment with the demethylating agent 5-aza-2'-deoxycytidine restored CMTM5 expression. In the OSCC cell lines CAL27 and GNM, the ectopic expression of CMTM5-v1 strongly inhibited cell proliferation and migration and induced apoptosis. In addition, CMTM5-v1 inhibited tumor formation in vivo. Therefore, CMTM5 might act as a putative tumor suppressor gene through promoter methylation in oral squamous cell carcinoma.

McAllister JM, Modi B, Miller BA, et al.
Overexpression of a DENND1A isoform produces a polycystic ovary syndrome theca phenotype.
Proc Natl Acad Sci U S A. 2014; 111(15):E1519-27 [PubMed] Article available free on PMC after 01/07/2015 Related Publications
Polycystic ovary syndrome (PCOS), characterized by increased ovarian androgen biosynthesis, anovulation, and infertility, affects 5-7% of reproductive-age women. Genome-wide association studies identified PCOS candidate loci that were replicated in subsequent reports, including DENND1A, which encodes a protein associated with clathrin-coated pits where cell-surface receptors reside. However, these studies provided no information about functional roles for DENND1A in the pathogenesis of PCOS. DENND1A protein was located in the cytoplasm as well as nuclei of theca cells, suggesting a possible role in gene regulation. DENND1A immunostaining was more intense in the theca of PCOS ovaries. Using theca cells isolated and propagated from normal cycling and PCOS women, we found that DENND1A variant 2 (DENND1A.V2) protein and mRNA levels are increased in PCOS theca cells. Exosomal DENND1A.V2 RNA was significantly elevated in urine from PCOS women compared with normal cycling women. Forced overexpression of DENND1A.V2 in normal theca cells resulted in a PCOS phenotype of augmented CYP17A1 and CYP11A1 gene transcription, mRNA abundance, and androgen biosynthesis. Knock-down of DENND1A.V2 in PCOS theca cells reduced androgen biosynthesis and CYP17A1 and CYP11A1 gene transcription. An IgG specific to DENND1A.V2 also reduced androgen biosynthesis and CYP17 and CYP11A1 mRNA when added to the medium of cultured PCOS theca cells. We conclude that the PCOS candidate gene, DENND1A, plays a key role in the hyperandrogenemia associated with PCOS. These observations have both diagnostic and therapeutic implications for this common disorder.

Wu G, Diaz AK, Paugh BS, et al.
The genomic landscape of diffuse intrinsic pontine glioma and pediatric non-brainstem high-grade glioma.
Nat Genet. 2014; 46(5):444-50 [PubMed] Article available free on PMC after 01/07/2015 Related Publications
Pediatric high-grade glioma (HGG) is a devastating disease with a less than 20% survival rate 2 years after diagnosis. We analyzed 127 pediatric HGGs, including diffuse intrinsic pontine gliomas (DIPGs) and non-brainstem HGGs (NBS-HGGs), by whole-genome, whole-exome and/or transcriptome sequencing. We identified recurrent somatic mutations in ACVR1 exclusively in DIPGs (32%), in addition to previously reported frequent somatic mutations in histone H3 genes, TP53 and ATRX, in both DIPGs and NBS-HGGs. Structural variants generating fusion genes were found in 47% of DIPGs and NBS-HGGs, with recurrent fusions involving the neurotrophin receptor genes NTRK1, NTRK2 and NTRK3 in 40% of NBS-HGGs in infants. Mutations targeting receptor tyrosine kinase-RAS-PI3K signaling, histone modification or chromatin remodeling, and cell cycle regulation were found in 68%, 73% and 59% of pediatric HGGs, respectively, including in DIPGs and NBS-HGGs. This comprehensive analysis provides insights into the unique and shared pathways driving pediatric HGG within and outside the brainstem.

Tabone T, Abuhusain HJ, Nowak AK, et al.
Multigene profiling to identify alternative treatment options for glioblastoma: a pilot study.
J Clin Pathol. 2014; 67(7):550-5 [PubMed] Related Publications
UNLABELLED: Glioblastoma (GBM) is a highly aggressive malignancy and the most effective treatment regime has a high relapse rate. Increasingly, the development of therapies involves defining drug-diagnostic combinations where the presence of a molecular target or marker identifies patients who are most likely to respond to a specific therapy. Trials in other solid cancers have demonstrated clear utility in the incorporation of biomarkers to stratify patients to targeted treatment, however, there are no mutations that are currently used to inform treatment options for GBM.
AIMS: We piloted the use of high-throughput next-generation sequencing technology to identify genetic mutations in 44 GBM specimens that may be amenable to current or future targeted therapeutic strategies.
METHOD: Somatic mutation profiling was performed using the AmpliSeq Cancer Hotspot Panel v2 and semiconductor sequencing technology.
RESULTS: A total of 66 mutations were detected in 35/44 (80%) patients. The number of mutations per tumour ranged from 0 to 4 (average per tumour=1.5). The most frequent mutations were in TP53 (n=12), PTEN (n=9), EGFR (n=8) and PIK3CA (n=5). Clinically actionable somatic mutations were detected in 24/35 (69%) patients.
CONCLUSIONS: This study demonstrates that the use of an 'off-the-shelf' oncogene primer panel and benchtop next-generation sequencer can identify mutations and potentially actionable targets in the majority of GBM patients. Data from this pilot highlights the potential for targeted genetic resequencing to identify mutations that may inform treatment options and predict outcomes.

Kocar M, Bozkurtlar E, Telli F, et al.
p95-HER2 and trastuzumab resistance in metastatic breast cancer; is immunohistochemistry appropriate?
J BUON. 2014 Jan-Mar; 19(1):245-9 [PubMed] Related Publications
PURPOSE: Unraveling the mechanisms underlying the resistance to trastuzumab is important for amending the prognosis of patients with human epidermal growth factor receptor 2 (HER2) positive metastatic breast cancer. Experimentally, it has been shown that p95-HER2 positive breast tumors are resistant to trastuzumab. The aim of this study was to investigate the predictive and prognostic importance of p95-HER2 expression by immunohistochemistry in HER2-positive metastatic breast cancer patients treated with trastuzumab.
METHODS: Only patients who had a histological diagnosis of HER2-positive metastatic breast cancer and who had received first line therapy containing trastuzumab were enrolled in the study. Immunohistochemistry was used to analyze p95-HER2 expression in the tissue blocks of the patients.
RESULTS: The study was performed on 38 patients aged between 30 and 84 years. In 14 patients (36.8%), p95-HER2 was positive, whereas it was negative in the remaining 24 patients (63.2%). There was no significant correlation between p95-HER2 expression and overall survival, response to trastuzumab, and progression-free survival (PFS).
CONCLUSION: Unlike previous reports, there was no correlation between the p95-HER2 expression and resistance to trastuzumab. It may be argued that an analysis using immunohistochemistry is inadequate for determining p95- HER2. In order to ascertain whether immunohistochemistry is an appropriate method, studies with larger patient groups are needed.

Martin RM, Kerr M, Teo MT, et al.
Post-transcriptional regulation of MRE11 expression in muscle-invasive bladder tumours.
Oncotarget. 2014; 5(4):993-1003 [PubMed] Article available free on PMC after 01/07/2015 Related Publications
Predictive assays are needed to help optimise treatment in muscle-invasive bladder cancer, where patients can be treated by either cystectomy or radical radiotherapy. Our finding that low tumour MRE11 expression is predictive of poor response to radiotherapy but not cystectomy was recently independently validated. Here we investigated further the mechanism underlying low MRE11 expression seen in poorly-responding patients. MRE11 RNA and protein levels were measured in 88 bladder tumour patient samples, by real-time PCR and immunohistochemistry respectively, and a panel of eight bladder cancer cell lines was screened for MRE11, RAD50 and NBS1 mRNA and protein expression. There was no correlation between bladder tumour MRE11 protein and RNA scores (Spearman's rho 0.064, p=0.65), suggesting MRE11 is controlled post-transcriptionally, a pattern confirmed in eight bladder cancer cell lines. In contrast, NBS1 and RAD50 mRNA and protein levels were correlated (p=0.01 and p=0.03, respectively), suggesting primary regulation at the level of transcription. MRE11 protein levels were correlated with NBS1 and RAD50 mRNA and protein levels, implicating MRN complex formation as an important determinant of MRE11 expression, driven by RAD50 and NBS1 expression. Our findings of the post-transcriptional nature of the control of MRE11 imply that any predictive assays used in patients need to be performed at the protein level rather than the mRNA level.

Pastorczak A, Szczepanski T, Trelinska J, et al.
Secondary acute monocytic leukemia positive for 11q23 rearrangement in Nijmegen breakage syndrome.
Pediatr Blood Cancer. 2014; 61(8):1469-71 [PubMed] Related Publications
Nijmegen breakage syndrome (NBS) is an autosomal recessive chromosomal instability disorder characterized by a high incidence of pediatric hematologic malignancies. Majority of patients affected are of Slavic origin and share the same founder mutation of 657del5 within the NBN gene encoding protein involved in DNA double-strand breaks (DSB) repair. We report a case of a pediatric patient with NBS, who developed t(9;11)/AF9-MLL-positive AML as a second malignancy after successful treatment of T-NHL. The coexistence of NBN and MLL mutations suggests that the profound dysfunction of NBN may promote alterations of MLL that is mediated by error-prone non-homologous end joining pathway particularly in patients treated with DNA topoisomerase II inhibitors.

Tural D, Serdengecti S, Demirelli F, et al.
Clinical significance of p95HER2 overexpression, PTEN loss and PI3K expression in p185HER2-positive metastatic breast cancer patients treated with trastuzumab-based therapies.
Br J Cancer. 2014; 110(8):1968-76 [PubMed] Article available free on PMC after 15/04/2015 Related Publications
BACKGROUND: Overexpression of p185HER2 is an established poor prognostic factor in breast cancer, portending an aggressive course and potential for early metastasis. On the other hand, monoclonal antibody trastuzumab is widely used in the clinic to target this overexpressed oncogene. Unfortunately, ~30-40% of all patients overexpressing HER2 respond to trastuzumab, warranting further research regarding the structure and additional modulation of the receptor. In this study, we aimed to investigate the response to trastuzumab in terms of the potential roles of several oncogenic pathways (phosphatase and tensin homologue (PTEN) and phosphatidylinositol 3-kinase (PI3K)) and a truncated receptor protein, p95HER2, retrospectively.
MATERIALS AND METHODS: Paraffin-embedded primary tumour tissues of 100 HER2-positive metastatic breast cancer patients who received trastuzumab with combination cytotoxic chemotherapy were analysed with immunohistochemical method for p95HER2, p85 (PI3K) and PTEN. Relationship between variables were tested via χ(2), Fischer's exact test and Mann-Whitney U tests, wherever appropriate. Progression-free survival (PFS) and overall survival (OS) periods were calculated with Kaplan-Meier method and survival curves of subgroups were compared with log-rank test.
RESULTS: Percentage of patients was found to be 33%, 57% and 42% positive for p95 expression, PTEN and PI3K, respectively. p95-expressing tumours had statistically lower response rates for trastuzumab than tumours not expressing p95 (P=0.001). On the contrary, PTEN-expressing tumours had statistically higher response rates for trastuzumab than tumours not expressing PTEN (P=0.012). PI3K expression had no significant effect on trastuzumab response. Median PFS for p95-expressing and not expressing tumours were 8 months (95% CI, 2.5-13.4 months) and 22 months (95% CI, 9.9-34 months), respectively (P=0.0001). Median PFS for PTEN-expressing and not expressing tumours were 15.3 months (95% CI, 12.6-34 months) and 12.1 months (95% CI, 7.9-16.2 months), respectively (P=0.04). Median OS for p95-expressing and not expressing tumours were 24 months (95% CI, 8.3-40.4 months) and 29.1 months (95% CI, 8.6-43.2 months), respectively (P=0.045). Median OS for PTEN-expressing and not expressing tumours were 25.1 months (95% CI, 7.5-40.1 months) and 26.8 months (95% CI, 8.1-42 months), respectively, which was not statistically significant (P=0.5). Level of PI3K expression had no effect on PFS and OS in our patient population. Presence of visceral metastases HR=2.38 ((95% CI, 1.2-4.5), P=0.009), p95 expression HR=2.1 ((95% CI, 1.1-3.7), P=0.03) and response to trastuzumab HR=2.2 ((95% CI, 1.18-4.47), P=0.014) are identified as factors independently affecting PFS. Response to trastuzumab HR=1.7 ((95% CI, 1.14-3.47), P=0.013) was identified as the single parameter influencing survival by Cox regression analysis.
CONCLUSIONS: Presence of p95 predicted a poorer response to trastuzumab treatment, shorter PFS and OS in our HER2-positive metastatic breast cancer cohort. In addition, loss of PTEN predicted a poorer response to trastuzumab treatment and shorter PFS but not OS. We could not find an effect of PI3K expression on the above-mentioned parameters.

Venkatesh GH, Manjunath VB, Mumbrekar KD, et al.
Polymorphisms in radio-responsive genes and its association with acute toxicity among head and neck cancer patients.
PLoS One. 2014; 9(3):e89079 [PubMed] Article available free on PMC after 15/04/2015 Related Publications
Cellular and molecular approaches are being explored to find a biomarker which can predict the development of radiation induced acute toxicity prior to radiation therapy. SNPs in radiation responsive genes may be considered as an approach to develop tools for finding the inherited basis of clinical radiosensitivity. The current study attempts to screen single nucleotide polymorphisms/deletions in DNA damage response, DNA repair, profibrotic cytokine as well as antioxidant response genes and its predictive potential with the normal tissue adverse reactions from 183 head and neck cancer patients undergoing platinum based chemoradiotherapy or radiotherapy alone. We analysed 22 polymorphisms in 17 genes having functional relevance to radiation response. Radiation therapy induced oral mucositis and skin erythema was considered as end point for clinical radiosensitivity. Direct correlation of heterozygous and mutant alleles with acute reactions as well as haplotype correlation revealed NBN variants to be of predictive significance in analysing oral mucositis prior to radiotherapy. In addition, genetic linkage disequilibrium existed in XRCC1 polymorphisms for >grade 2 oral mucositis and skin reaction indicating the complex inheritance pattern. The current study indicates an association for polymorphism in NBN with normal tissue radiosensitivity and further warrants the replication of such studies in a large set of samples.

Wang X, Beitler JJ, Wang H, et al.
Honokiol enhances paclitaxel efficacy in multi-drug resistant human cancer model through the induction of apoptosis.
PLoS One. 2014; 9(2):e86369 [PubMed] Article available free on PMC after 15/04/2015 Related Publications
Resistance to chemotherapy remains a major obstacle in cancer therapy. This study aimed to evaluate the molecular mechanism and efficacy of honokiol in inducing apoptosis and enhancing paclitaxel chemotherapy in pre-clinical multi-drug resistant (MDR) cancer models, including lineage-derived human MDR (KB-8-5, KB-C1, KB-V1) and their parental drug sensitive KB-3-1 cancer cell lines. In vitro analyses demonstrated that honokiol effectively inhibited proliferation in KB-3-1 cells and the MDR derivatives (IC50 ranging 3.35 ± 0.13 µg/ml to 2.77 ± 0.22 µg/ml), despite their significant differences in response to paclitaxel (IC50 ranging 1.66 ± 0.09 ng/ml to 6560.9 ± 439.52 ng/ml). Honokiol induced mitochondria-dependent and death receptor-mediated apoptosis in MDR KB cells, which was associated with inhibition of EGFR-STAT3 signaling and downregulation of STAT3 target genes. Combined treatment with honokiol and paclitaxel synergistically augmented cytotoxicity in MDR KB cells, compared with treatment with either agent alone in vitro. Importantly, the combined treatment significantly inhibited in vivo growth of KB-8-5 tumors in a subcutaneous model. Tumor tissues from the combination group displayed a significant inhibition of Ki-67 expression and an increase in TUNEL-positive cells compared with the control group. These results suggest that targeting multidrug resistance using honokiol in combination with chemotherapy drugs may provide novel therapeutic opportunities.

Watanabe Y, Maeda I, Oikawa R, et al.
Aberrant DNA methylation status of DNA repair genes in breast cancer treated with neoadjuvant chemotherapy.
Genes Cells. 2013; 18(12):1120-30 [PubMed] Related Publications
Dysregulation of homologous recombination (HR) DNA repair has been implicated in breast carcinogenesis and chemosensitivity. Here, we investigated the methylation status of sixteen HR genes and analyzed their association with tumor subtypes and responses to neoadjuvant chemotherapy. Core specimens were obtained before neoadjuvant chemotherapy from sixty cases of primary breast cancer of the following four subgroups: luminal breast cancer (LBC) with pathological complete response (pCR), LBC with stable disease, triple-negative breast cancer (TNBC) with pCR and TNBC with poor response. The aberrant DNA methylation status of the following HR related-genes was analyzed using bisulfite-pyrosequencing: BRCA1, BRCA2, BARD1, MDC1, RNF8, RNF168, UBC13, ABRA1, PALB2, RAD50, RAD51, RAD51C, MRE11, NBS1, CtIP and ATM. Among the genes analyzed, only the incidence of BRCA1 and RNF8 methylation was significantly higher in TNBC than that in LBC. Whereas the incidence of BRCA1 methylation was tended to be higher in pCR cases than in poor-response cases in TNBC, that of RNF8 was significantly lower in pCR cases than in poor-response cases. Our results indicate that the methylation status of HR genes was not generally associated with TNBC subtype or chemosensitivity although hypermethylation of BRCA1 is associated with TNBC subtype and may impact chemosensitivity.

Hu DG, Hickey TE, Irvine C, et al.
Identification of androgen receptor splice variant transcripts in breast cancer cell lines and human tissues.
Horm Cancer. 2014; 5(2):61-71 [PubMed] Related Publications
The androgen receptor (AR) is widely expressed in human tissues and has biological function in many male and female organs. In particular, the AR plays a critical role in the biology and pathology of the prostate gland. AR activity inhibits breast growth and has pleiotropic actions in breast cancer that are subtype-dependent. Expression of AR splice variants (ARVs) and their role in prostate carcinogenesis has been elucidated in recent studies. We hypothesised that ARVs are also expressed in breast cancers and other hormone sensitive tissues. Herein, the expression of five previously identified ARV transcripts with documented transcriptional capacity (AR-V1, -V3, -V4, -V7, and -V9) was examined in 6 breast (MFM223, MDA-MB-453, MDA-MB-231, ZR75.1, MCF-7, T47D), two prostate (VCaP, LNCaP), and one liver (HepG2) cancer cell lines, a human embryonic kidney cell line (HEK293), and a panel of RNAs representing 21 different human tissues. Four ARVs (V1, V3, V7, V9) were detected to some degree in almost all cell lines and tissues. In addition, four novel ARVs containing a cryptic exon 9 (CE9) were detected in MDA-MB-453 and VCaP cells. Sequencing of ARV amplicons revealed a single nucleotide substitution within CE3 in lung and placental tissue samples that could be translated as an Ile (ATT)>Val (GTT) substitution in the AR-V7 variant protein. Collectively, these data provides insight into the potential complexity of AR transcriptional splicing events in breast cancer cell lines and diverse human tissues, thereby establishing a rationale for further exploration of ARVs in breast cancer and other human pathologies.

Laetsch TW, Liu X, Vu A, et al.
Multiple components of the spliceosome regulate Mcl1 activity in neuroblastoma.
Cell Death Dis. 2014; 5:e1072 [PubMed] Article available free on PMC after 15/04/2015 Related Publications
Cancer treatments induce cell stress to trigger apoptosis in tumor cells. Many cancers repress these apoptotic signals through alterations in the Bcl2 proteins that regulate this process. Therapeutics that target these specific survival biases are in development, and drugs that inhibit Bcl2 activities have shown clinical activity for some cancers. Mcl1 is a survival factor for which no effective antagonists have been developed, so it remains a principal mediator of therapy resistance, including to Bcl2 inhibitors. We used a synthetic-lethal screening strategy to identify genes that regulate Mcl1 survival activity using the pediatric tumor neuroblastoma (NB) as a model, as a large subset are functionally verified to be Mcl1 dependent and Bcl2 inhibitor resistant. A targeted siRNA screen identified genes whose knockdown restores sensitivity of Mcl1-dependent NBs to ABT-737, a small molecule inhibitor of Bcl2, BclXL and BclW. Three target genes that shifted the ABT-737 IC50 >1 log were identified and validated: PSMD14, UBL5 and PRPF8. The latter two are members of a recently characterized subcomplex of the spliceosome that along with SART1 is responsible for non-canonical 5'-splice sequence recognition in yeast. We showed that SART1 knockdown similarly sensitized Mcl1-dependent NB to ABT-737 and that triple knockdown of UBL5/PRPF8/SART1 phenocopied direct MCL1 knockdown, whereas having no effect on Bcl2-dependent NBs. Both genetic spliceosome knockdown or treatment with SF3b-interacting spliceosome inhibitors like spliceostatin A led to preferential pro-apoptotic Mcl1-S splicing and reduced translation and abundance of Mcl1 protein. In contrast, BN82865, which inhibits the second transesterification step in terminal spliceosome processing, did not have this effect. These findings demonstrate a prominent role for the spliceosome in mediating Mcl1 activity and suggest that drugs that target either the specific UBL5/PRPF8/SART1 subcomplex or SF3b functions may have a role as cancer therapeutics by attenuating the Mcl1 survival bias present in numerous cancers.

Grupp K, Boumesli R, Tsourlakis MC, et al.
The prognostic impact of high Nijmegen breakage syndrome (NBS1) gene expression in ERG-negative prostate cancers lacking PTEN deletion is driven by KPNA2 expression.
Int J Cancer. 2014; 135(6):1399-407 [PubMed] Related Publications
The Nijmegen breakage syndrome (NBS1) gene was suggested as a prostate cancer susceptibility gene. This study was undertaken to determine, whether NBS1 expression is linked to clinically or molecularly relevant subgroups of prostate cancer. NBS1 expression was analyzed by immunohistochemistry on a tissue microarray containing 11,152 prostate cancer specimens. NBS1 expression was absent or only weakly detectable in benign prostate. In prostate cancers, NBS1 expression was found in 81.3% of interpretable tumors and was considered strong in 41.3% of cases. NBS1 upregulation was tightly linked to ERG-positive cancers (p<0.0001). Within ERG-negative cancers, strong NBS1 immunostaining was linked to advanced pathological tumor stage, high Gleason grade, and positive nodal status (p<0.0001 each), while high NBS1 immunostaining was only weakly associated with advanced pathological tumor stage in ERG-positive cancers (p=0.0099). A comparison with chromosomal deletions revealed a strong NBS1 upregulation in PTEN-deleted cancers, while deletions of 3p13, 5q21 and 6q15 did not affect NBS1 expression. High NBS1 expression was linked to biochemical recurrence in ERG-negative and PTEN non-deleted cancers (p<0.0001), which was largely driven by high KPNA2 karyopherin alpha 2 expression. In conclusion, our study identifies an association of NBS1 expression with surrogates of genomic instability in prostate cancer including TMPRSS2-ERG rearrangements and PTEN deletion. The prognostic impact of NBS1 expression in ERG-negative, PTEN non-deleted cancers was dependent of the expression status of its interaction partner KPNA2.

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