Gene Summary

Gene:MIB1; mindbomb E3 ubiquitin protein ligase 1
Aliases: MIB, DIP1, ZZZ6, DIP-1, LVNC7, ZZANK2
Summary:This gene encodes a protein containing multiple ankyrin repeats and RING finger domains that functions as an E3 ubiquitin ligase. The encoded protein positively regulates Notch signaling by ubiquitinating the Notch receptors, thereby facilitating their endocytosis. This protein may also promote the ubiquitination and degradation of death-associated protein kinase 1 (DAPK1). [provided by RefSeq, Jun 2013]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:E3 ubiquitin-protein ligase MIB1
Source:NCBIAccessed: 11 March, 2017


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 11 March 2017 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 11 March, 2017 using data from PubMed, MeSH and CancerIndex

Latest Publications: MIB1 (cancer-related)

Veneroni S, Dugo M, Daidone MG, et al.
Applicability of Under Vacuum Fresh Tissue Sealing and Cooling to Omics Analysis of Tumor Tissues.
Biopreserv Biobank. 2016; 14(6):480-490 [PubMed] Related Publications
CONTEXT: Biobanks of frozen human normal and malignant tissues represent a valuable source for "omics" analysis in translational cancer research and molecular pathology. However, the success of molecular and cellular analysis strongly relies on the collection, handling, storage procedures, and quality control of fresh human tissue samples.
OBJECTIVE: We tested whether under vacuum storage (UVS) effectively preserves tissues during the time between surgery and storage for "omics" analyses.
DESIGN: Normal and matched tumor specimens, obtained from 16 breast, colon, or lung cancer patients and 5 independent mesenchymal tumors, were dissected within 20 minutes from surgical excision and divided in three to five aliquots; for each tissue sample, one aliquot was snap-frozen in liquid nitrogen (defined as baseline or T0 samples), and the other portions were sealed into plastic bags and kept at 4°C for 1, 24, 48, or 72 hours under vacuum and then frozen. The tissue and molecular preservation under vacuum was evaluated over time in terms of histomorphology, transcription (Illumina microarrays), protein (surface-enhanced laser desorption/ionization-time of flight/mass spectrometry and Western blot), and metabolic profile (nuclear magnetic resonance spectroscopy).
RESULTS: Tissue morphology, Mib-1, and vimentin immunostaining were preserved over time without signs of tissue degradation. Principal variance component analysis showed that time of storage had a minimal effect on gene expression or the proteome, but affected the preservation of some metabolites to a greater extent. UVS did not impact the RNA and protein integrity or specific phosphorylation sites on mTOR and STAT3. Measurement of metabolites revealed pronounced changes after 1 hour of storage.
CONCLUSIONS: Our results show that UVS can preserve tissue specimens for histological, transcriptomic, and proteomic examinations up to 48 hours and possibly longer, whereas it has limitations for metabolomic applications.

Leijon H, Salmenkivi K, Heiskanen I, et al.
HuR in pheochromocytomas and paragangliomas - overexpression in verified malignant tumors.
APMIS. 2016; 124(9):757-63 [PubMed] Related Publications
Pheochromocytomas and paragangliomas are rare, neural crest-originating, neuroendocrine tumors. HuR is an mRNA-binding protein of the ELAV/Hu-protein family, which participates in posttranscriptional regulation of many cancer-associated genes. HuR expression has been connected with aggressive behavior of several malignancies. Cyclooxygenase-2 (COX-2) is also expressed in several malignant tumors, and its expression is regulated by HuR. Tissue microarray of 153 primary pheochromocytomas and paragangliomas was investigated for the expression of HuR and COX-2 proteins by immunohistochemistry using two different HuR antibodies (HuR19F12 and HuR3A). In these tumors, the expression of both intranuclear and cytoplasmic HuR was detectable. Increased cytoplasmic HuR expression was significantly associated with metastatic tumors. Increased COX-2 and MIB-1 expression also was associated with metastatic potential, and moreover, HuR and COX-2 expression correlated with each other. Our data suggest that increased expression of HuR protein is associated with metastatic potential of paragangliomas and pheochromocytomas, and COX-2 seems to be a target of HuR.

Vij M, Agrawal V, Kumar A, Pandey R
Evaluation of biologic potential and risk stratification for predicting disease-free survival after resection of primary gastrointestinal stromal tumor: A multivariate clinicopathological study.
Indian J Cancer. 2015 Jul-Sep; 52(3):351-7 [PubMed] Related Publications
BACKGROUND AND OBJECTIVES: Gastrointestinal stromal tumor (GIST) is mesenchymal neoplasms of the gastrointestinal tract, which express CD117, a c-kit proto-oncogene protein and show gain of function mutation of c-kit gene. Apart from the presence of metastasis, the criteria to differentiate benign and malignant GISTs are not well-defined. Although a variety of prognostic factors have been investigated, no method has yet proven sufficient to enable reliable determination of malignancy in all cases. This study was planned to risk stratify the GIST cases with respect to the various clinicopathological features and to identify prognostic factors in GIST.
MATERIALS AND METHODS: n histological and immunohistochemical analysis, 121 cases of GIST were identified. MIB-1 (Ki-67) labeling index (LI) was performed in 60 cases. Follow-up data was available for 93 patients. A P < 0.05 was taken as significant.
RESULTS: Larger tumor size, high mitotic activity and Ki-67 LI of >10% were identified as significant predictors of disease-free survival in univariate analysis (P < 0.0001). Other factors of statistically significant value were a high cellularity (P < 0.0027), nuclear pleomorphism (P = 0.0002), epithelioid cell type (P = 0.0098), presence of tumor necrosis (P < 0.01), presence of skeinoid fibers (P = 0.042), S-100 negativity (P = 0.025). Extra-gastrointestinal GIST and metastasis were more frequently associated with progressive disease (PD) as compared with GIST (P < 0.0004), (P < 0.0001). On multivariate analysis size (P = 0.0025), Ki-67 labeling index (P = 0.0186) and mitotic count (P = 0.0375) emerged as independent prognostic predictors of PD.
CONCLUSION: This study suggests that GIST in Asian population may have a different phenotype with some predilection to nodal metastasis. Of all the features studied, tumor size and mitotic index are the best prognosticators in GIST with the addition of Ki-67 LI, wherever available.

Liu Q, Thompson BA, Ward RL, et al.
Understanding the Pathogenicity of Noncoding Mismatch Repair Gene Promoter Variants in Lynch Syndrome.
Hum Mutat. 2016; 37(5):417-26 [PubMed] Related Publications
Lynch syndrome is the most common familial cancer condition that mainly predisposes to tumors of the colon and endometrium. Cancer susceptibility is caused by the autosomal dominant inheritance of a loss-of-function mutation or epimutation in one of the DNA mismatch repair (MMR) genes. Cancer risk assessment is often possible with nonsynonymous coding region mutations, but in many cases patients present with DNA sequence changes within noncoding regions, including the promoters, of MMR genes. The pathogenic role of promoter variants, and hence clinical significance, is unclear and this hinders the clinical management of carriers. In this review, we provide an overview of the classification of MMR gene variants, outline the laboratory assays and online resources that can be used to assess the causality of promoter variants in Lynch syndrome, and highlight some of the practical challenges of demonstrating the pathogenicity of these variants. In conclusion, we propose a guide that could be integrated into the current InSiGHT classification scheme to help determine if a MMR gene promoter variant is pathogenic.

Meyer MJ, Lapcevic R, Romero AE, et al.
mutation3D: Cancer Gene Prediction Through Atomic Clustering of Coding Variants in the Structural Proteome.
Hum Mutat. 2016; 37(5):447-56 [PubMed] Article available free on PMC after 01/05/2017 Related Publications
A new algorithm and Web server, mutation3D (http://mutation3d.org), proposes driver genes in cancer by identifying clusters of amino acid substitutions within tertiary protein structures. We demonstrate the feasibility of using a 3D clustering approach to implicate proteins in cancer based on explorations of single proteins using the mutation3D Web interface. On a large scale, we show that clustering with mutation3D is able to separate functional from nonfunctional mutations by analyzing a combination of 8,869 known inherited disease mutations and 2,004 SNPs overlaid together upon the same sets of crystal structures and homology models. Further, we present a systematic analysis of whole-genome and whole-exome cancer datasets to demonstrate that mutation3D identifies many known cancer genes as well as previously underexplored target genes. The mutation3D Web interface allows users to analyze their own mutation data in a variety of popular formats and provides seamless access to explore mutation clusters derived from over 975,000 somatic mutations reported by 6,811 cancer sequencing studies. The mutation3D Web interface is freely available with all major browsers supported.

Moghadasi S, Eccles DM, Devilee P, et al.
Classification and Clinical Management of Variants of Uncertain Significance in High Penetrance Cancer Predisposition Genes.
Hum Mutat. 2016; 37(4):331-6 [PubMed] Related Publications
In 2008, the International Agency for Research on Cancer (IARC) proposed a system for classifying sequence variants in highly penetrant breast and colon cancer susceptibility genes, linked to clinical actions. This system uses a multifactorial likelihood model to calculate the posterior probability that an altered DNA sequence is pathogenic. Variants between 5%-94.9% (class 3) are categorized as variants of uncertain significance (VUS). This interval is wide and might include variants with a substantial difference in pathogenicity at either end of the spectrum. We think that carriers of class 3 variants would benefit from a fine-tuning of this classification. Classification of VUS to a category with a defined clinical significance is very important because for carriers of a pathogenic mutation full surveillance and risk-reducing surgery can reduce cancer incidence. Counselees who are not carriers of a pathogenic mutation can be discharged from intensive follow-up and avoid unnecessary risk-reducing surgery. By means of examples, we show how, in selected cases, additional data can lead to reclassification of some variants to a different class with different recommendations for surveillance and therapy. To improve the clinical utility of this classification system, we suggest a pragmatic adaptation to clinical practice.

Denysenko T, Annovazzi L, Cassoni P, et al.
WNT/β-catenin Signaling Pathway and Downstream Modulators in Low- and High-grade Glioma.
Cancer Genomics Proteomics. 2016 Jan-Feb; 13(1):31-45 [PubMed] Related Publications
BACKGROUND: Aberrant activation of the canonical Wingless-type MMTV integration site family (WNT)/β-catenin signaling pathway is critical for gliomas.
MATERIALS AND METHODS: In 74 gliomas of different histological grade and in 24 glioblastoma cell lines, protein expression of WNT member 3a (WNT3a), β-catenin and transcription factor 4 (TCF4) was investigated by immunohistochemistry, western blotting, immunofluorescence and immunocytochemistry. In tumors and cell lines, WNT3A expression was assessed at the mRNA level by quantitative real-time polymerase chain reaction.
RESULTS: WNT3a was overexpressed at the protein and mRNA levels in malignant astrocytic tumors and cell lines. Cytoplasmic expression of β-catenin was detected in high-grade gliomas and cell lines, with evidence of nuclear translocation on fractionated protein extracts. Activating mutations in the β-catenin encoding gene (CTNNB1) were excluded by direct sequencing. TCF4 was statistically correlated with Ki-67/MIB-1 and cyclin D1 labeling indices.
CONCLUSION: Expression of WNT3a, cytoplasmic β-catenin and TCF4 was significantly associated with the histological malignancy grade and with a worse prognosis for patients with glioma.

Ekong R, Nellist M, Hoogeveen-Westerveld M, et al.
Variants Within TSC2 Exons 25 and 31 Are Very Unlikely to Cause Clinically Diagnosable Tuberous Sclerosis.
Hum Mutat. 2016; 37(4):364-70 [PubMed] Article available free on PMC after 01/05/2017 Related Publications
Inactivating mutations in TSC1 and TSC2 cause tuberous sclerosis complex (TSC). The 2012 international consensus meeting on TSC diagnosis and management agreed that the identification of a pathogenic TSC1 or TSC2 variant establishes a diagnosis of TSC, even in the absence of clinical signs. However, exons 25 and 31 of TSC2 are subject to alternative splicing. No variants causing clinically diagnosed TSC have been reported in these exons, raising the possibility that such variants would not cause TSC. We present truncating and in-frame variants in exons 25 and 31 in three individuals unlikely to fulfil TSC diagnostic criteria and examine the importance of these exons in TSC using different approaches. Amino acid conservation analysis suggests significantly less conservation in these exons compared with the majority of TSC2 exons, and TSC2 expression data demonstrates that the majority of TSC2 transcripts lack exons 25 and/or 31 in many human adult tissues. In vitro assay of both exons shows that neither exon is essential for TSC complex function. Our evidence suggests that variants in TSC2 exons 25 or 31 are very unlikely to cause classical TSC, although a role for these exons in tissue/stage specific development cannot be excluded.

Zhao M, Liu Y, O'Mara TA
ECGene: A Literature-Based Knowledgebase of Endometrial Cancer Genes.
Hum Mutat. 2016; 37(4):337-43 [PubMed] Article available free on PMC after 01/05/2017 Related Publications
Endometrial cancer (EC) ranks as the sixth common cancer for women worldwide. To better distinguish cancer subtypes and identify effective early diagnostic biomarkers, we need improved understanding of the biological mechanisms associated with EC dysregulated genes. Although there is a wealth of clinical and molecular information relevant to EC in the literature, there has been no systematic summary of EC-implicated genes. In this study, we developed a literature-based database ECGene (Endometrial Cancer Gene database) with comprehensive annotations. ECGene features manual curation of 414 genes from thousands of publications, results from eight EC gene expression datasets, precomputation of coexpressed long noncoding RNAs, and an EC-implicated gene interactome. In the current release, we generated and comprehensively annotated a list of 458 EC-implicated genes. We found the top-ranked EC-implicated genes are frequently mutated in The Cancer Genome Atlas (TCGA) tumor samples. Furthermore, systematic analysis of coexpressed lncRNAs provided insight into the important roles of lncRNA in EC development. ECGene has a user-friendly Web interface and is freely available at http://ecgene.bioinfo-minzhao.org/. As the first literature-based online resource for EC, ECGene serves as a useful gateway for researchers to explore EC genetics.

Cahill DP, Sloan AE, Nahed BV, et al.
The role of neuropathology in the management of patients with diffuse low grade glioma: A systematic review and evidence-based clinical practice guideline.
J Neurooncol. 2015; 125(3):531-49 [PubMed] Related Publications
TARGET POPULATION: Adult patients (age ≥18 years) who have suspected low-grade diffuse glioma.
QUESTION: What are the optimal neuropathological techniques to diagnose low-grade diffuse glioma in the adult?
RECOMMENDATION: LEVEL I: Histopathological analysis of a representative surgical sample of the lesion should be used to provide the diagnosis of low-grade diffuse glioma.
LEVEL III: Both frozen section and cytopathologic/smear evaluation should be used to aid the intra-operative assessment of low-grade diffuse glioma diagnosis. A resection specimen is preferred over a biopsy specimen, to minimize the potential for sampling error issues.
TARGET POPULATION: Patients with histologically-proven WHO grade II diffuse glioma.
QUESTION: In adult patients (age ≥18 years) with histologically-proven WHO grade II diffuse glioma, is testing for IDH1 mutation (R132H and/or others) warranted? If so, is there a preferred method?

Gilbert DC, Al-Saadi R, Thway K, et al.
Defining a New Prognostic Index for Stage I Nonseminomatous Germ Cell Tumors Using CXCL12 Expression and Proportion of Embryonal Carcinoma.
Clin Cancer Res. 2016; 22(5):1265-73 [PubMed] Article available free on PMC after 01/05/2017 Related Publications
PURPOSE: Up to 50% of patients diagnosed with stage I nonseminomatous germ cell tumors (NSGCTs) harbor occult metastases. Patients are managed by surveillance with chemotherapy at relapse or adjuvant treatment up front. Late toxicities from chemotherapy are increasingly recognized. Based on a potential biologic role in germ cells/tumors and pilot data, our aim was to evaluate tumor expression of the chemokine CXCL12 alongside previously proposed markers as clinically useful biomarkers of relapse.
EXPERIMENTAL DESIGN: Immunohistochemistry for tumor expression of CXCL12 was assessed as a biomarker of relapse alongside vascular invasion, histology (percentage embryonal carcinoma), and MIB1 staining for proliferation in formalin-fixed paraffin-embedded orchidectomy samples from patients enrolled in the Medical Research Council's TE08/22 prospective trials of surveillance in stage I NSGCTs.
RESULTS: TE08/TE22 trial patients had a 76.4% 2-year relapse-free rate, and both CXCL12 expression and percentage embryonal carcinoma provided prognostic value independently of vascular invasion (stratified log rank test P = 0.006 for both). There was no additional prognostic value for MIB1 staining. A model using CXCL12, percentage embryonal carcinoma, and VI defines three prognostic groups that were independently validated.
CONCLUSIONS: CXCL12 and percentage embryonal carcinoma both stratify patients' relapse risk over and above vascular invasion alone. This is anticipated to improve the stratification of patients and identify high-risk cases to be considered for adjuvant therapy.

Bu H, Narisu N, Schlick B, et al.
Putative Prostate Cancer Risk SNP in an Androgen Receptor-Binding Site of the Melanophilin Gene Illustrates Enrichment of Risk SNPs in Androgen Receptor Target Sites.
Hum Mutat. 2016; 37(1):52-64 [PubMed] Article available free on PMC after 01/05/2017 Related Publications
Genome-wide association studies have identified genomic loci, whose single-nucleotide polymorphisms (SNPs) predispose to prostate cancer (PCa). However, the mechanisms of most of these variants are largely unknown. We integrated chromatin-immunoprecipitation-coupled sequencing and microarray expression profiling in TMPRSS2-ERG gene rearrangement positive DUCaP cells with the GWAS PCa risk SNPs catalog to identify disease susceptibility SNPs localized within functional androgen receptor-binding sites (ARBSs). Among the 48 GWAS index risk SNPs and 3,917 linked SNPs, 80 were found located in ARBSs. Of these, rs11891426:T>G in an intron of the melanophilin gene (MLPH) was within a novel putative auxiliary AR-binding motif, which is enriched in the neighborhood of canonical androgen-responsive elements. T→G exchange attenuated the transcriptional activity of the ARBS in an AR reporter gene assay. The expression of MLPH in primary prostate tumors was significantly lower in those with the G compared with the T allele and correlated significantly with AR protein. Higher melanophilin level in prostate tissue of patients with a favorable PCa risk profile points out a tumor-suppressive effect. These results unravel a hidden link between AR and a functional putative PCa risk SNP, whose allele alteration affects androgen regulation of its host gene MLPH.

Manzoni M, Roversi G, Di Bella C, et al.
Solid cell nests of the thyroid gland: morphological, immunohistochemical and genetic features.
Histopathology. 2016; 68(6):866-74 [PubMed] Related Publications
AIMS: The correct identification of solid cell nests (SCNs) is an important issue in thyroid pathology because of the spectrum of differential diagnoses of this type of lesion.
METHODS AND RESULTS: Ten cases of 295 consecutive thyroidectomies showed the presence of SCNs at histological examination. The identification of the exact SCN type required the distinction of the cystic and solid pattern; SCNs were usually composed of a mixture of main cells (MCs) and C-cells (CCs). The immunohistochemical calcitonin stain identified CCs easily, both inside SCNs and dispersed in islets at the periphery. For the characterization of MCs, we added the utility of p40 to p63. The use of thyroid transcription factor-1 (TTF-1) helped in their identification, as MCs did not react with this marker; the combination of TTF-1 and p40 or p63 IHC stains was useful for the characterization of cystic SCNs of both types 3 and 4. The negativity of mouse monoclonal mesothelioma antibody (HMBE-1) and a very low proliferative index (MIB-1) supported the diagnosis. [Correction added on 23 November 2015, after online publication: MIB-1 was incorrectly defined, the expanded form was deleted.] We discourage the use of galectin-3 (Gal-3) and cytokeratin-19 (CK-19), as they have an important overlap with papillary thyroid carcinoma. The complete absence of any B-Raf proto-oncogene, serine/threonine kinase (BRAF) mutations is an additional fundamental finding.
CONCLUSIONS: We reviewed the most relevant morphological and immunohistochemical features of SCNs and have provided a genetic analysis of the BRAF gene because of its expanding use in thyroid pathology.

Niroula A, Vihinen M
Classification of Amino Acid Substitutions in Mismatch Repair Proteins Using PON-MMR2.
Hum Mutat. 2015; 36(12):1128-34 [PubMed] Related Publications
Variations in mismatch repair (MMR) system genes are causative of Lynch syndrome and other cancers. Thousands of variants have been identified in MMR genes, but the clinical relevance is known for only a small proportion. Recently, the InSiGHT group classified 2,360 MMR variants into five classes. One-third of variants, majority of which is nonsynonymous variants, remain to be of uncertain clinical relevance. Computational tools can be used to prioritize variants for disease relevance investigations. Previously, we classified 248 MMR variants as likely pathogenic and likely benign using PON-MMR. We have developed a novel tool, PON-MMR2, which is trained on a larger and more reliable dataset. In performance comparison, PON-MMR2 outperforms both generic tolerance prediction methods as well as methods optimized for MMR variants. It achieves accuracy and MCC of 0.89 and 0.78, respectively, in cross-validation and 0.86 and 0.69, respectively, on an independent test dataset. We classified 354 class 3 variants in InSiGHT database as well as all possible amino acid substitutions in four MMR proteins. Likely harmful variants mainly appear in the protein core, whereas likely benign variants are on the surface. PON-MMR2 is a highly reliable tool to prioritize variants for functional analysis. It is freely available at http://structure.bmc.lu.se/PON-MMR2/.

Tafreshi NK, Lloyd MC, Proemsey JB, et al.
Evaluation of CAIX and CAXII Expression in Breast Cancer at Varied O2 Levels: CAIX is the Superior Surrogate Imaging Biomarker of Tumor Hypoxia.
Mol Imaging Biol. 2016; 18(2):219-31 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
PURPOSE: Hypoxia is commonly observed in regions of primary tumors and metastases, and is associated with resistance to treatment, more aggressive tumor phenotypes and poor prognosis. Reliable and validated imaging biomarkers of hypoxia are needed for pre-clinical studies and clinical use. Expression of cell-surface carbonic anhydrases IX and XII (CAIX and CAXII) in tumor cells has been associated with tumor hypoxia. CAIX and CAXII specific antibodies conjugated to fluorescent dye were evaluated for the non-invasive detection of hypoxia in vivo.
PROCEDURES: Human breast cancer cell lines (MCF10A, DCIS, MCF7, ZR-75.1 and MDA-mb231) were characterized for CAIX and CAXII expression by real-time RT-PCR and immunocytochemistry (ICC) under normoxic and hypoxic conditions. Immunohistochemical (IHC) staining of CAIX, CAXII and the commercially available exogenous hypoxia marker, pimonidazole, was performed using sections of ZR-75.1 and MDA-mb-231 orthotopic breast cancer xenograft tumors from nude mice. In vivo fluorescence imaging of ZR-75.1 tumors in animals housed at varied levels of oxygen was used to quantify the relative uptake of the CAIX and CAXII agents and a commercially available sulfonamide-based agent. Corresponding tumor sections were IHC stained for CAIX, CAXII and pimonidazole.
RESULTS: CAIX mRNA expression was significantly higher (p < 0.05) in hypoxia for all cell lines, which was in agreement with protein expression by ICC. CAXII expression was mixed, with a modest hypoxia-related increase in two cell lines (p < 0.05) and no change in others. Quantified IHC staining of ZR-75.1 and MDA-mb-231 tumor sections showed that CAIX and CAXII expression was elevated in regions with pimonidazole staining, but CAXII levels were lower than CAIX. Tumor uptake of the CAIX targeted agent, and IHC staining of CAIX and pimonidazole in corresponding tumor sections were correlated, and co-registered, and shown to be significantly elevated by level of oxygenation (p < 0.001): hypoxia > normoxia > hyperoxia. However, the CAXII and sulfonamide agents were not significantly correlated with hypoxia.
CONCLUSION: These studies suggest that the fluorescently labeled CAIX-specific agent is a more robust indicator of hypoxia in vivo compared to the CAXII-specific agent or the agent specific to the CA active site.

Ronowicz A, Janaszak-Jasiecka A, Skokowski J, et al.
Concurrent DNA Copy-Number Alterations and Mutations in Genes Related to Maintenance of Genome Stability in Uninvolved Mammary Glandular Tissue from Breast Cancer Patients.
Hum Mutat. 2015; 36(11):1088-99 [PubMed] Related Publications
Somatic mosaicism for DNA copy-number alterations (SMC-CNAs) is defined as gain or loss of chromosomal segments in somatic cells within a single organism. As cells harboring SMC-CNAs can undergo clonal expansion, it has been proposed that SMC-CNAs may contribute to the predisposition of these cells to genetic disease including cancer. Herein, the gross genomic alterations (>500 kbp) were characterized in uninvolved mammary glandular tissue from 59 breast cancer patients and matched samples of primary tumors and lymph node metastases. Array-based comparative genomic hybridization showed 10% (6/59) of patients harbored one to 359 large SMC-CNAs (mean: 1,328 kbp; median: 961 kbp) in a substantial portion of glandular tissue cells, distal from the primary tumor site. SMC-CNAs were partially recurrent in tumors, albeit with considerable contribution of stochastic SMC-CNAs indicating genomic destabilization. Targeted resequencing of 301 known predisposition and somatic driver loci revealed mutations and rare variants in genes related to maintenance of genomic integrity: BRCA1 (p.Gln1756Profs*74, p.Arg504Cys), BRCA2 (p.Asn3124Ile), NCOR1 (p.Pro1570Glnfs*45), PALB2 (p.Ser500Pro), and TP53 (p.Arg306*). Co-occurrence of gross SMC-CNAs along with point mutations or rare variants in genes responsible for safeguarding genomic integrity highlights the temporal and spatial neoplastic potential of uninvolved glandular tissue in breast cancer patients.

Wilson AJ, Saskowski J, Barham W, et al.
Thymoquinone enhances cisplatin-response through direct tumor effects in a syngeneic mouse model of ovarian cancer.
J Ovarian Res. 2015; 8:46 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
BACKGROUND: Ovarian cancer is the most lethal gynecologic malignancy characterized by the frequent development of resistance to platinum chemotherapy. Finding new drug combinations to overcome platinum resistance is a key clinical challenge. Thymoquinone (TQ) is a component of black seed oil that exerts multiple anti-tumorigenic effects on cells, including inhibition of NF-κB and promotion of DNA damage. We aimed to determine whether TQ enhances cisplatin cytotoxicity in cultured ovarian cancer cells and in an established murine syngeneic model of ovarian cancer.
METHODS: Ovarian cancer cell viability in vitro was measured by sulforhodamine B (SRB) assays, and drug interactions tested for synergism by isobologram analysis. ID8-NGL mouse ovarian cancer cells stably expressing an NF-κB reporter transgene were injected intra-peritoneally into C57BL/6 mice. After 30 day TQ and/or cisplatin treatment, we measured the following indices: tumor burden (ascites volume, number of peritoneal implants and mesenteric tumor mass); NF-κB reporter activity (luciferase assay); protein expression of the double-strand DNA break marker, pH2AX(ser139), the proliferation markers, Ki67/mib-1 and PCNA, and the apoptosis markers, cleaved caspase-3, cleaved PARP and Bax; and mRNA expression of NF-κB targets, TNF-α and IL-1β. Two-tailed Mann-Whitney tests were used for measuring differences between groups in mouse experiments.
RESULTS: In SRB assays, TQ and cisplatin synergized in ID8-NGL cells. In mice, cisplatin significantly reduced cell proliferation and increased apoptosis in tumors, resulting in decreased overall tumor burden. Combining TQ with cisplatin further decreased these indices, indicating co-operative effects between the drugs. TQ treatment promoted cisplatin-induced pH2AX expression in cultured cells and in tumors. While NF-κB inhibition by TQ induced anti-tumor effects in vitro, we made the unexpected observation that TQ alone increased both tumor NF-κB activity and formation of ascites in vivo.
CONCLUSIONS: TQ enhanced cisplatin-mediated cytoxicity in ovarian cancer cells in vitro and in a mouse syngeneic model, effects associated with increased DNA damage. However, our results strongly caution that TQ treatment alone may have an overall deleterious effect in the immunocompetent host through stimulation of ascites. Since TQ is a potential candidate for future clinical trials in ovarian cancer patients, this finding has considerable potential relevance to the clinic.

Carozzi F, Tamburrino L, Bisanzi S, et al.
Are biomarkers evaluated in biopsy specimens predictive of prostate cancer aggressiveness?
J Cancer Res Clin Oncol. 2016; 142(1):201-12 [PubMed] Related Publications
PURPOSE: To evaluate biomarkers involved in biological pathways for prostate cancer (PCa) progression, measured in biopsy specimens, in order to distinguish patients at higher risk for fatal PCa and thus improve the initial management of disease.
METHODS: Retrospective case-control study. In 129 PCa patients who underwent ultrasound-guided needle prostate biopsy and subsequent radical prostatectomy from 1987 to 1999 at the University Hospital of Careggi, we evaluated: (1) mRNA expression of the serine 2 (TMPRSS2): erythroblastosis virus E26 oncogene homolog (ERG); (2) expression of matrix metalloproteinases (MMP)-2 and 9 (epithelial and stromal); (3) expression of androgen receptor; (4) expression of prognostic marker Ki67 (MIB1); (5) presence and typing of human papilloma virus; (6) DNA methylation of CpG islands of several genes involved in PCa progression.
RESULTS: The cohort consists of 38 cases (patients with PCa and died of PCa within 10 years from diagnosis) and 91 controls (patients with PCa but alive 10 years after diagnosis). Gleason bioptic score, epithelial MMP expression and SERPINB5 methylation correlated with statistically significant increase in death risk OR. Compared with patients with high level of MMP, patients with low level of MMP had OR for specific death 4.78 times higher (p = 0.0066). After adjustment for age and Gleason score, none of the investigated biomarkers showed increased OR for PCa death.
CONCLUSIONS: Our preliminary results suggest that evaluation, in prostate biopsy specimens, of a panel of biomarkers known to be involved in PCa progression is poorly indicative of tumor outcome.

Kalogeraki A, Tamiolakis D, Matalliotaki C, et al.
Rev Med Chir Soc Med Nat Iasi. 2015 Apr-Jun; 119(2):454-60 [PubMed] Related Publications
OBJECTIVE: The first cytological study examining the expression of P53, BCL2 and MIB 1 expressions in correlation with other clinicopathological parameters in ascitic fluids of patients with serous ovarian carcinomas.
MATERIALS AND METHODS: Fifty women 35-75 years old were diagnosed cytologically and confirmed histologically after operation in the University Hospital of Crete. All carcinomas were serous type and eight(8) of grade I, eighteen (18) of grade II and twenty two (22) of grade III. All carcinomas were staged according to the Figo criteria. Fifteen (15) were of Figo stage III and thirty five (35) were of Figo stage IV. For p53 and bcl-2, staining was evaluated on a semiquantitative scale depending on the number of cells showing positivity. For MIB1, the percentage of positive nuclei was calculated. Main outcome measure(s): The expression of P53, BCL2 and MIB 1 (Ki 67) correlated with tumor grade and Figo stages were estimated by chi-square (χ2).
RESULTS: The expression of P53 and MIB1 were found to be statistically significant (p < 0.005) correlated with Figo stage and tumor grade. A statistical significant correlation was also found between BCL2 expression and tumor Grade ( p < 0.005) but not between BCL2 expression and Figo Stage. The study found a high expression of P53 (64%) and MIB1 (72%) and an expression of BCL2 (48%) in ascitic fluid of patients with ovarian carcinoma. A statistically significant correlation between P53 and MIB1 expression correlated with tumor grade and Figo stage (p < 0.005) and a statistically significant correlation between BCL2 expression and tumor grade but no with the Figo stage was found (p < 0.005). There was a positive correlation between P53 and MIB1. No significant association was found between P53 and BCL2 expression or MIB1 labeling index.
CONCLUSION(S): Our data show significant differences in the expression of these markers in ovarian tumors and suggest a possible role for these tumor-associated genes as supplemental tools in prognosis and further definition of the biologic potential of these tumors.

Meka Pb, Jarjapu S, Nanchari SR, et al.
LCN2 Promoter Methylation Status as Novel Predictive Marker for Microvessel Density and Aggressive Tumor Phenotype in Breast Cancer Patients.
Asian Pac J Cancer Prev. 2015; 16(12):4965-9 [PubMed] Related Publications
LCN2 (Lipocalin 2) is a 25 KD secreted acute phase protein, reported to be a novel regulator of angiogenesis in breast cancer. Up regulation of LCN2 had been observed in multiple cancers including breast cancer, pancreatic cancer and ovarian cancer. However, the role of LCN2 promoter methylation in the formation of microvessels is poorly understood. The aim of this study was to analyze the association of LCN 2 promoter methylation with microvessel formation and tumor cell proliferation in breast cancer patients. The LCN2 promoter methylation status was studied in 64 breast cancer tumors by methylation specific PCR (MSP). Evaluation of microvessel density (MVD) and Ki67 cell proliferation index was achieved by immunohistochemical staining using CD34 and MIB-1 antibodies, respectively. LCN2 promoter unmethylation status was observed in 43 (67.2%) of breast cancer patients whereas LCN2 methylation status was seen in 21 (32.8%). Further, LCN2 promoter unmethylation status was associated with aggressive tumor phenotype and elevated mean MVD in breast cancer patients.

Purkait S, Sharma V, Jha P, et al.
EZH2 expression in gliomas: Correlation with CDKN2A gene deletion/ p16 loss and MIB-1 proliferation index.
Neuropathology. 2015; 35(5):421-31 [PubMed] Related Publications
Enhancer of zeste homolog 2 (EZH2) mediated down-regulation of CDKN2A/p16 has been observed in cell lines as well as in a few carcinomas. However, there is no study correlating EZH2 expression with CDKN2A/p16 status in gliomas. Hence, the present study was conducted to evaluate EZH2 expression in astrocytic and oligodendroglial tumors and correlate with CDKN2A/p16 status as well as MIB-1 labeling index (LI). Gliomas of all grades (n = 118) were studied using immunohistochemistry to assess EZH2, p16 and MIB-1 LI and fluorescence in situ hybrization to evaluate CDKN2A gene status. EZH2 expression and CDKN2A homozygous deletion (HD) were both significantly more frequent in high-grade gliomas (HGG). Further, strong EZH2 expression (LI ≥ 25%) was significantly more common in HGGs without CDKN2A HD (48.7%; 19/39) as compared to cases with deletion (15.8%; 3/19). Loss of p16 expression was noted in 100% and 51.3% of CDKN2A deleted and non-deleted tumors, respectively. Notably, 80% (16/20) of the CDKN2A non-deleted HGGs with p16 loss had strong EZH2 expression, in contrast to only 15.8% (3/19) in the deleted group. Loss of p16 expression significantly correlated with MIB-1 LI, irrespective of EZH2 status. Thus, this study shows that EZH2 expression correlates with tumor grade in both astrocytic and oligodendroglial tumors and hence can be used as a diagnostic marker to differentiate between low and HGGs. Further, this is the first report demonstrating an inverse correlation of strong EZH2 expression with CDKN2A HD in HGGs. Loss of p16 protein expression is mostly attributable to CDKN2A HD and correlates significantly with MIB-1 LI. Notably, our study for the first time suggests a possible epigenetic mechanism of p16 loss in CDKN2A non-deleted HGGs mediated by strong EZH2 expression. A hypothetical model for control of proliferative activity in low versus HGGs is therefore proposed.

Benderska N, Dittrich AL, Knaup S, et al.
miRNA-26b Overexpression in Ulcerative Colitis-associated Carcinogenesis.
Inflamm Bowel Dis. 2015; 21(9):2039-51 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
BACKGROUND: Longstanding ulcerative colitis (UC) bears a high risk for development of UC-associated colorectal carcinoma (UCC). The inflammatory microenvironment influences microRNA expression, which in turn deregulates target gene expression. microRNA-26b (miR-26b) was shown to be instrumental in normal tissue growth and differentiation. Thus, we aimed to investigate the impact of miR-26b in inflammation-associated colorectal carcinogenesis.
METHODS: Two different cohorts of patients were investigated. In the retrospective group, a tissue microarray with 38 samples from 17 UC/UCC patients was used for miR-26b in situ hybridization and quantitative reverse transcription polymerase chain reaction analyses. In the prospective group, we investigated miR-26b expression in 25 fresh-frozen colon biopsies and corresponding serum samples of 6 UC and 15 non-UC patients, respectively. In silico analysis, Ago2-RNA immunoprecipitation, luciferase reporter assay, quantitative reverse transcription polymerase chain reaction examination, and miR-26b mimic overexpression were employed for target validation.
RESULTS: miR-26b expression was shown to be upregulated with disease progression in tissues and serum of UC and UCC patients. Using miR-26b and Ki-67 expression levels, an UCC was predicted with high accuracy. We identified 4 novel miR-26b targets (DIP1, MDM2, CREBBP, BRCA1). Among them, the downregulation of the E3 ubiquitin ligase DIP1 was closely related to death-associated protein kinase stabilization along the normal mucosa-UC-UCC sequence. In silico functional pathway analysis revealed that the common cellular pathways affected by miR-26b are highly related to cancerogenesis and the development of gastrointestinal diseases.
CONCLUSIONS: We suggest that miR-26b could serve as a biomarker for inflammation-associated processes in the gastrointestinal system. Because miR-26b expression is downregulated in sporadic colon cancer, it could discriminate between UCC and the sporadic cancer type.

Yadav S, Mukhopadhyay S, Anbalagan M, Makridakis N
Somatic Mutations in Catalytic Core of POLK Reported in Prostate Cancer Alter Translesion DNA Synthesis.
Hum Mutat. 2015; 36(9):873-80 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
DNA polymerase kappa is a Y-family polymerase that participates to bypass the damaged DNA known as translesion synthesis (TLS) polymerase. Higher frequency of mutations in DNA polymerase kappa (POLK) recently been reported in prostate cancer. We sequenced entire exons of the POLK gene on genomic DNA from 40 prostate cancers and matched normal samples. We identified that 28% of patients have somatic mutations in the POLK gene of the prostate tumors. Mutations in these prostate cancers have somatic mutation spectra, which are dominated by C-to-T transitions. In the current study, we further investigate the effect of p.E29K, p.G154E, p.F155S, p.E430K, p.L442F, and p.E449K mutations on the biochemical properties of the polymerase in vitro, using TLS assay and nucleotide incorporation fidelity, following site-directed mutagenesis bacterial expression, and purification of the respective polymerase variants. We report that following missense mutations p.E29K, p.G154E, p.F155S, p.E430K, and p.L442F significantly diminished the catalytic efficiencies of POLK with regard to the lesion bypass (AP site). POLK variants show extraordinarily low fidelity by misincorporating T, C, and G as compared to wild-type variants. Taken together, these results suggest that interfering with normal polymerase kappa function by these mutations may be involved in prostate carcinogenesis.

Sasaki H, Hirose Y, Yazaki T, et al.
Upfront chemotherapy and subsequent resection for molecularly defined gliomas.
J Neurooncol. 2015; 124(1):127-35 [PubMed] Related Publications
Functional preservation is critical in glioma surgery, and the extent of resection influences survival outcome. Neoadjuvant chemotherapy is a promising option because of its potential to facilitate tumor shrinkage and maximum tumor resection. The object of this study was to assess the utility of the neoadjuvant strategy in a prospective series of gliomas with favorable molecular status. Twenty-six consecutive cases of diffuse gliomas of WHO grade II or III with either 1p19q codeletion or MGMT methylation were treated with upfront chemotherapy following maximal safe removal. In cases of incomplete initial surgery, second-look resection was intended after tumor volume decrease by chemotherapy. Among 22 evaluable cases, chemotherapy led to a median change in the sum of the product of perpendicular diameters of -35 %, and 14 out of the 22 cases (64 %) showed objective response. Second-look resection after tumor volume decrease was performed in 12 out of 19 cases of incomplete initial surgery (GTR/STR 9, removal of residual methionine PET uptake 3). The median progression-free survival among the 22 patients with grade II tumors was 57 months, with some cases showing durable progression-free survival after second-look resection. MIB-1 indices of the second-look resected tumors were lower than those of the initial tumors, and the methylation status of the MGMT gene was unchanged. Neoadjuvant chemotherapy based on molecular guidance often produces significant volume decrease of incompletely resected gliomas. Radical second-look resection is an optional advantage of upfront chemotherapy for chemosensitive gliomas compared with initial radiotherapy.

Germain-Genevois C, Garandeau O, Couillaud F
Detection of Brain Tumors and Systemic Metastases Using NanoLuc and Fluc for Dual Reporter Imaging.
Mol Imaging Biol. 2016; 18(1):62-9 [PubMed] Related Publications
PURPOSE: Bioluminescence imaging (BLI) is a technique with a low background noise and high sensitivity which is widely used in mice models in oncology. We aimed to assess BLI efficiency of the new luciferase NanoLuc (Nluc) for glioblastoma cell lines and tumors, including for dual reporter applications of deep brain tumors and systemic metastasis when combined with firefly luciferase (Fluc).
PROCEDURES: U87 cells were genetically modified for constitutive production of either Nluc, Fluc, or both and assayed for luciferase activity and BLI on cell lysates, living cells, subcutaneous tumors, brain tumors, and systemic metastases.
RESULTS: In vitro, light production by Nluc activity is higher than Fluc. In vivo, Nluc allows for tumor detection including for deep brain tumors and systemic metastases.
CONCLUSIONS: Nluc appears to be a useful tool to combine with Fluc for dual imaging in vivo using bioluminescence, allowing for the detection of distinct events in deep tissues within the same organism.

Yoo B, Kavishwar A, Ross A, et al.
In Vivo Detection of miRNA Expression in Tumors Using an Activatable Nanosensor.
Mol Imaging Biol. 2016; 18(1):70-8 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
PURPOSE: The development of tools for the analysis of microRNA (miRNA) function in tumors can advance our diagnostic and prognostic capabilities. Here, we describe the development of technology for the profiling of miRNA expression in the tumors of live animals.
PROCEDURES: The approach is based on miRNA nanosensors consisting of sensor oligonucleotides conjugated to magnetic nanoparticles for systemic delivery. Feasibility was demonstrated for the detection of miR-10b, implicated in epithelial to mesenchymal transition and the development of metastasis. The miR-10b nanosensor was tested in vivo in two mouse models of cancer. In the first model, mice were implanted subcutaneously with MDA-MB-231-luc-D3H2LN tumors, in which miR-10b was inhibited. In the second model, mice were implanted bilaterally with metastatic MDA-MB-231 and nonmetastatic MCF-7 cells. The nanosensors were injected intravenously, and fluorescence intensity in the tumors was monitored over time.
RESULTS: We showed that the described nanosensors are capable of discriminating between tumors based on their expression of miR-10b. Radiant efficiency was higher in the miR-10b-active tumors than in the miR-10b-inhibited tumors and in the MDA-MB-231 tumors relative to the MCF-7 tumors.
CONCLUSIONS: The described technology provides an important tool that could be used to answer questions about microRNA function in cancer.

Iobagiu C, Lambert C, Raica M, et al.
Loss of heterozygosity in tumor tissue in hormonal receptor genes is associated with poor prognostic criteria in breast cancer.
Cancer Genet. 2015; 208(4):135-42 [PubMed] Related Publications
The estrogen receptors (ESRα and β) and the androgen receptor (AR) mediate genomic and non-genomic effects on breast tumor growth and proliferation. We analyzed 101 breast cancer patients for allelic loss in microsatellites located in regulatory regions of the ESRs and AR genes in breast cancer tumors. The loss of heterozygosity (LOH) at these loci was found in 36.2% of tumor tissues (ductal carcinoma cases), for 19% of cases at the ESRα locus, for 16% at the ESRβ locus, and for 10% at the AR locus. The LOH in at least one of the two ESR loci was correlated to poor prognosis criteria: ESR-negative status (P = 0.007), PR-negative status (P = 0.003), high Scarff-Bloom-Richardson (SBR) grade (P = 0.0007), high MIB-1 proliferation index (P = 0.02), and diminished apoptosis potential (TP53-positive status, P = 0.018). When AR was also considered, the LOH in at least one of the three loci was associated with ESR-negative status (P = 0.036), PR-negative status (P = 0.027), high SBR grade (P = 0.005), high mitotic index (P = 0.0002), TP53-positive status (P = 0.029), and proliferating index (high MIB-1, P = 0.03). Allelic loss was observed in 26% of normal tissue adjacent to tumor with LOH at the ESRα locus and in 7.1% of tumors with LOH at the ESRβ locus. The LOH in tumor tissue in the regulatory regions of ESRα, ESRβ, and AR genes has potentially synergistic effects on tumor proliferation, histological aggressiveness, down-regulation of ESRα and progesterone receptor (PR) genes, and is an early genetic alteration in cancer that is possibly involved in passage to estrogen independence.

Vuletic I, Liu J, Wu H, et al.
Establishment of an mKate2-Expressing Cell Line for Non-Invasive Real-Time Breast Cancer In Vivo Imaging.
Mol Imaging Biol. 2015; 17(6):811-8 [PubMed] Related Publications
PURPOSE: Non-invasive real-time in vivo imaging experiments using mice as animal models have become crucial for understanding cancer development and treatment. In this study, we have developed and validated a new breast cancer cell line MDA-MB-435s that stably express a far-red fluorescence protein (mKate2) and that could serve as a highly valuable cell model for studying breast cancer detection and therapy using in vivo fluorescence imaging in nude mice.
PROCEDURES: The new cell line (MDA-MB-435s-mKate2) was constructed by plasmid transfection. The stability and sensitivity of mKate2, and the cell biological activities, were tested in vitro using different experimental approaches. For its potential use in tumor growth research and drug therapy in vivo, MDA-MB-435s-mKate2 was validated using the immunocompromised Balb/c nude mice tumor model. In addition, the new cell line has been characterized as a luteinizing hormone-releasing hormone receptor (LHRHR) positive cell line.
RESULTS: Firstly, MDA-MB-435s-mKate2 has shown a stable chromosomal integration of the amplified mKate2 gene and good fluorescence sensitivity for detection using a fluorescence reflectance imaging (FRI) device. Compared to its parental cell line, no significant difference in cell migration, proliferation, and clone formation was observed in vitro. Secondly, using the quantification of tumor-fluorescence surface area in live animals, we were able to monitor and detect the tumor progress or tumor inhibition rate (by Paclitaxel treatment) non-invasively and in real-time. Furthermore, MDA-MB-435s-mKate2 has been positively tested for LHRHR; these findings open the possibility to use this cell line for future studies of breast cancer therapy based on LHRH analogs in vivo.
CONCLUSION: In the present research, we have successfully built the MDA-MB-435s-mKate2 cell line that can be used as a suitable cell model for breast cancer therapy and anti-cancer drug evaluation by non-invasive fluorescence imaging in mice.

Lehner S, Lang C, Kaissis G, et al.
(124)I-PET Assessment of Human Sodium Iodide Symporter Reporter Gene Activity for Highly Sensitive In Vivo Monitoring of Teratoma Formation in Mice.
Mol Imaging Biol. 2015; 17(6):874-83 [PubMed] Related Publications
PURPOSE: Pluripotent stem cell (PSC)-based therapies possess great potential to restore the function of irreversibly damaged organs. PSCs can be differentiated in vitro into any cell type. However, pluripotent potential bears the risk of teratoma formation. In vivo monitoring of teratoma formation is indispensable, as 100 % purity of the cell preparation cannot be achieved. We aimed at establishing the human sodium iodide symporter (hNIS) as reporter gene for PET monitoring of teratoma formation.
PROCEDURES: Murine PSC stably expressing hNIS were injected into the hind limbs of SCID mice to induce teratoma formation. Positron emission tomography (PET) scans were acquired weekly between days 14 and 42 after transplantation. Two teratomas were excised at each time point for histology and size measurement. Tracer uptake was correlated with teratoma weight. Specificity of tumoural iodine uptake was assessed by blocking hNIS in vivo with perchlorate.
RESULTS: Neither hNIS expression nor I-124 exposure adversely impacted viability or differentiation potential of PSCs. Iodine uptake was highly specific in teratomas, as in vivo blocking of hNIS with perchlorate led to uptake rates comparable to tracer uptake in non-transgene tumours. Tumour mass and tracer uptake showed a positive correlation.
CONCLUSIONS: This is the first study to generate stably hNIS-expressing murine PSCs. Since the differentiation potential was preserved, hNIS-expressing cells are suitable for PSC-based forward programming approaches. Teratoma formation from undifferentiated cells can be monitored in vivo by PET with high specificity on a quantitative level. Due to its anticipated lack of immunogenicity in humans, hNIS is a promising reporter gene for clinical translation.

Sharon C, Baranwal S, Patel NJ, et al.
Inhibition of insulin-like growth factor receptor/AKT/mammalian target of rapamycin axis targets colorectal cancer stem cells by attenuating mevalonate-isoprenoid pathway in vitro and in vivo.
Oncotarget. 2015; 6(17):15332-47 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
We observed a co-upregulation of the insulin-like growth factor receptor (IGF-1R)/AKT/mammalian target of rapamycin (mTOR) [InAT] axis and the mevalonate-isoprenoid biosynthesis (MIB) pathways in colorectal cancer stem cells (CSCs) in an unbiased approach. Hence, we hypothesized that the InAT axis might regulate the MIB pathway to govern colorectal CSCs growth. Stimulation (IGF-1) or inhibition (IGF-1R depletion and pharmacological inhibition of IGF-1R/mTOR) of the InAT axis produced induction or attenuation of CSC growth as well as expression of CSC markers and self-renewal factors respectively. Intriguingly, activation of the InAT axis (IGF-1) caused significant upregulation of the MIB pathway genes (both mRNA and protein); while its inhibition produced the opposite effects in colonospheres. More importantly, supplementation with dimethylallyl- and farnesyl-PP, MIB metabolites downstream of isopentenyl-diphosphate delta isomerase (IDI), but not mevalonate and isopentenyl-pp that are upstream of IDI, resulted in a near-complete reversal of the suppressive effect of the InAT axis inhibitors on CSCs growth. The latter findings suggest a specific regulation of the MIB pathway by the InAT axis distal to the target of statins that inhibit 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR). Effects of IGF-1R inhibition on colonic CSCs proliferation and the MIB pathway were confirmed in an 'in vivo' HCT-116 xenograft model. These observations establish a novel mechanistic link between the InAT axis that is commonly deregulated in colorectal cancer and the MIB pathway in regulation of colonic CSCs growth. Hence, the InAT-MIB corridor is a novel target for developing paradigm shifting optimum anti-CSCs therapies for colorectal cancer.

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