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1.  Redox cycling compounds generate H2O2 in HTS buffers containing strong reducing reagents – real hits or promiscuous artifacts? 
Redox cycling compounds (RCCs) generate µM concentrations of hydrogen peroxide (H2O2) in the presence of strong reducing agents, common buffer components used to maintain the catalytic activity and/or folding of target proteins for high throughput screening (HTS) assays. H2O2 generated by RCCs can indirectly inhibit the catalytic activity of proteins by oxidizing accessible cysteine, tryptophan, methionine, histidine or selenocysteine residues, and indeed several important classes of protein targets are susceptible to H2O2-mediated inactivation; protein tyrosine phosphatases, cysteine proteases, and metalloenzymes. The main sources of H2O2 in cells are the Nox enzyme/SOD systems, peroxisome metabolism, and the autoxidation of reactive chemicals by enzyme mediated redox cycling at both the microsomal and mitochondrial sites of electron transport. Given the role of H2O2 as a second messenger involved in the regulation of many signaling pathways it is hardly surprising that compounds which can generate intracellular H2O2 by enzyme mediated redox cycling would have pleiotropic effects. RCCs can therefore have serious negative consequences for the probe and/or lead generation process: primary HTS assay hit rates may be inflated by RCC false positives; critical resources will be diverted to develop and implement follow up assays to distinguish RCCs from real hits; and screening databases will become annotated with the promiscuous activity of RCCs. In an attempt to mitigate the serious impact of RCCs on probe and lead generation, two groups have independently developed assays to indentify RCCs.
doi:10.1016/j.cbpa.2010.10.022
PMCID: PMC3040250  PMID: 21075044
2.  Development of a 384-Well Colorimetric Assay to Quantify Hydrogen Peroxide Generated by the Redox Cycling of Compounds in the Presence of Reducing Agents 
We report here the development and optimization of a simple 384-well colorimetric assay to measure H2O2 generated by the redox cycling of compounds incubated with reducing agents in high-throughput screening (HTS) assay buffers. The phenol red-horseradish peroxidase (HRP) assay readily detected H2O2 either added exogenously or generated by the redox cycling of compounds in dithiothreitol (DTT). The generation of H2O2 was dependent on the concentration of both the compound and DTT and was abolished by catalase. Although both DTT and tris(2-carboxyethyl)-phosphine sustain the redox cycling generation of H2O2 by a model quinolinedione, 6-chloro-7-(2-morpholin-4-yl-ethylamino)-quinoline-5,8-dione (NSC 663284; DA3003-1), other reducing agents such as β-mercaptoethanol, glutathione, and cysteine do not. The assay is compatible with HTS. Once terminated, the assay signal was stable for at least 5 h, allowing for a reasonable throughput. The assay tolerated up to 20% dimethyl sulfoxide, allowing a wide range of compound concentrations to be tested. The assay signal window was robust and reproducible with average Z-factors of ≥0.8, and the redox cycling generation of H2O2 by DA3003-1 in DTT exhibited an average 50% effective concentration of 0.830 ± 0.068 μM. Five of the mitogen-activated protein kinase phosphatase (MKP) 1 inhibitors identified in an HTS were shown to generate H2O2 in the presence of DTT, and their inhibition of MKP-1 activity was shown to be time dependent and was abolished or significantly reduced by either 100 U of catalase or by higher DTT levels. A cross-target query of the PubChem database with three structurally related pyrimidotriazinediones revealed active flags in 36–39% of the primary screening assays. Activity was confirmed against a number of targets containing active site cysteines, including protein tyrosine phosphatases, cathepsins, and caspases, as well as a number of cellular cytotoxicity assays. Rather than utilize resources to conduct a hit characterization effort involving several secondary assays, the phenol red-HRP assay provides a simple, rapid, sensitive, and inexpensive method to identify compounds that redox cycle in DTT or tris(2-carboxyethyl)phosphine to produce H2O2 that may indirectly modulate target activity and represent promiscuous false-positives from a primary screen.
doi:10.1089/adt.2008.151
PMCID: PMC2752819  PMID: 18699726
3.  Development of a 384-Well Colorimetric Assay to Quantify Hydrogen Peroxide Generated by the Redox Cycling of Compounds in the Presence of Reducing Agents 
Abstract
We report here the development and optimization of a simple 384-well colorimetric assay to measure H2O2 generated by the redox cycling of compounds incubated with reducing agents in high-throughput screening (HTS) assay buffers. The phenol red-horseradish peroxidase (HRP) assay readily detected H2O2 either added exogenously or generated by the redox cycling of compounds in dithiothreitol (DTT). The generation of H2O2 was dependent on the concentration of both the compound and DTT and was abolished by catalase. Although both DTT and tris(2-carboxyethyl)-phosphine sustain the redox cycling generation of H2O2 by a model quinolinedione, 6-chloro-7-(2-morpholin-4-yl-ethylamino)-quinoline-5,8-dione (NSC 663284; DA3003-1), other reducing agents such as β-mercaptoethanol, glutathione, and cysteine do not. The assay is compatible with HTS. Once terminated, the assay signal was stable for at least 5 h, allowing for a reasonable throughput. The assay tolerated up to 20% dimethyl sulfoxide, allowing a wide range of compound concentrations to be tested. The assay signal window was robust and reproducible with average Z-factors of ≥0.8, and the redox cycling generation of H2O2 by DA3003-1 in DTT exhibited an average 50% effective concentration of 0.830 μ 0.068 μM. Five of the mitogen-activated protein kinase phosphatase (MKP) 1 inhibitors identified in an HTS were shown to generate H2O2 in the presence of DTT, and their inhibition of MKP-1 activity was shown to be time dependent and was abolished or significantly reduced by either 100 U of catalase or by higher DTT levels. A cross-target query of the PubChem database with three structurally related pyrimidotriazinediones revealed active flags in 36–39% of the primary screening assays. Activity was confirmed against a number of targets containing active site cysteines, including protein tyrosine phosphatases, cathepsins, and caspases, as well as a number of cellular cytotoxicity assays. Rather than utilize resources to conduct a hit characterization effort involving several secondary assays, the phenol red-HRP assay provides a simple, rapid, sensitive, and inexpensive method to identify compounds that redox cycle in DTT or tris(2-carboxyethyl)phosphine to produce H2O2 that may indirectly modulate target activity and represent promiscuous false-positives from a primary screen.
doi:10.1089/adt.2008.151
PMCID: PMC2752819  PMID: 18699726
4.  Pathway analysis of kidney cancer using proteomics and metabolic profiling 
Molecular Cancer  2006;5:64.
Background
Renal cell carcinoma (RCC) is the sixth leading cause of cancer death and is responsible for 11,000 deaths per year in the US. Approximately one-third of patients present with disease which is already metastatic and for which there is currently no adequate treatment, and no biofluid screening tests exist for RCC. In this study, we have undertaken a comprehensive proteomic analysis and subsequently a pathway and network approach to identify biological processes involved in clear cell RCC (ccRCC). We have used these data to investigate urinary markers of RCC which could be applied to high-risk patients, or to those being followed for recurrence, for early diagnosis and treatment, thereby substantially reducing mortality of this disease.
Results
Using 2-dimensional electrophoresis and mass spectrometric analysis, we identified 31 proteins which were differentially expressed with a high degree of significance in ccRCC as compared to adjacent non-malignant tissue, and we confirmed some of these by immunoblotting, immunohistochemistry, and comparison to published transcriptomic data. When evaluated by several pathway and biological process analysis programs, these proteins are demonstrated to be involved with a high degree of confidence (p values < 2.0 E-05) in glycolysis, propanoate metabolism, pyruvate metabolism, urea cycle and arginine/proline metabolism, as well as in the non-metabolic p53 and FAS pathways. In a pilot study using random urine samples from both ccRCC and control patients, we performed metabolic profiling and found that only sorbitol, a component of an alternative glycolysis pathway, is significantly elevated at 5.4-fold in RCC patients as compared to controls.
Conclusion
Extensive pathway and network analysis allowed for the discovery of highly significant pathways from a set of clear cell RCC samples. Knowledge of activation of these processes will lead to novel assays identifying their proteomic and/or metabolomic signatures in biofluids of patient at high risk for this disease; we provide pilot data for such a urinary bioassay. Furthermore, we demonstrate how the knowledge of networks, processes, and pathways altered in kidney cancer may be used to influence the choice of optimal therapy.
doi:10.1186/1476-4598-5-64
PMCID: PMC1665458  PMID: 17123452
5.  Integrated Profiling of MicroRNAs and mRNAs: MicroRNAs Located on Xq27.3 Associate with Clear Cell Renal Cell Carcinoma 
PLoS ONE  2010;5(12):e15224.
Background
With the advent of second-generation sequencing, the expression of gene transcripts can be digitally measured with high accuracy. The purpose of this study was to systematically profile the expression of both mRNA and miRNA genes in clear cell renal cell carcinoma (ccRCC) using massively parallel sequencing technology.
Methodology
The expression of mRNAs and miRNAs were analyzed in tumor tissues and matched normal adjacent tissues obtained from 10 ccRCC patients without distant metastases. In a prevalence screen, some of the most interesting results were validated in a large cohort of ccRCC patients.
Principal Findings
A total of 404 miRNAs and 9,799 mRNAs were detected to be differentially expressed in the 10 ccRCC patients. We also identified 56 novel miRNA candidates in at least two samples. In addition to confirming that canonical cancer genes and miRNAs (including VEGFA, DUSP9 and ERBB4; miR-210, miR-184 and miR-206) play pivotal roles in ccRCC development, promising novel candidates (such as PNCK and miR-122) without previous annotation in ccRCC carcinogenesis were also discovered in this study. Pathways controlling cell fates (e.g., cell cycle and apoptosis pathways) and cell communication (e.g., focal adhesion and ECM-receptor interaction) were found to be significantly more likely to be disrupted in ccRCC. Additionally, the results of the prevalence screen revealed that the expression of a miRNA gene cluster located on Xq27.3 was consistently downregulated in at least 76.7% of ∼50 ccRCC patients.
Conclusions
Our study provided a two-dimensional map of the mRNA and miRNA expression profiles of ccRCC using deep sequencing technology. Our results indicate that the phenotypic status of ccRCC is characterized by a loss of normal renal function, downregulation of metabolic genes, and upregulation of many signal transduction genes in key pathways. Furthermore, it can be concluded that downregulation of miRNA genes clustered on Xq27.3 is associated with ccRCC.
doi:10.1371/journal.pone.0015224
PMCID: PMC3013074  PMID: 21253009
6.  Xp11 Translocation Renal Cell Carcinoma (RCC): Extended Immunohistochemical Profile Emphasizing Novel RCC Markers 
Xp11 translocation renal cell carcinoma (RCC) harbor various TFE3 gene fusions, and are known to underexpress epithelial immunohistochemical (IHC) markers such as cytokeratin and EMA relative to usual adult type RCC; however, their profile in reference to other IHC markers that are differentially expressed in other subtypes of RCC has not been systematically assessed. Few therapeutic targets have been identified in these aggressive cancers. We created 2 tissue microarrays (TMA) containing five 1.4-mm cores from each of 21 Xp11 translocation RCC (all confirmed by TFE3 IHC, 6 further confirmed by genetics), 7 clear cell RCC (CCRCC), and 6 papillary RCC (PRCC). These TMA were labeled for a panel of IHC markers. In contrast to earlier published data, Xp11 translocation RCC frequently expressed renal transcription factors PAX8 (16/21 cases) and PAX2 (14/21 cases), whereas only 1 of 21 cases focally expressed MiTF and only 5 of 21 overexpressed p21. Although experimental data suggest otherwise, Xp11 translocation RCC did not express WT-1 (0/21 cases). Although 24% of Xp11 translocation RCC expressed HIF-1α (like CCRCC), unlike CCRCC CA IX expression was characteristically only focal (mean 6% cell labeling) in Xp11 translocation RCC. Other markers preferentially expressed in CCRCC or PRCC, such as HIG-2, claudin 7, and EpCAM, yielded inconsistent results in Xp11 translocation RCC. Xp11 translocation RCC infrequently expressed Ksp-cadherin (3/21 cases) and c-kit (0/21 cases), markers frequently expressed in chromophobe RCC. Using an H-score that is the product of intensity and percentage labeling, Xp11 translocation RCC expressed higher levels of phosphorylated S6, a measure of mTOR pathway activation (mean H score = 88), than did CCRCC (mean H score = 54) or PRCC (mean H score = 44). In conclusion, in contrast to prior reports, Xp11 translocation RCC usually express PAX2 and PAX8 but do not usually express MiTF. Although they may express HIF-1α, they only focally express the downstream target CA IX. They inconsistently express markers associated with other RCC subtypes, further highlighting the lack of specificity of the latter markers. TFE3 and Cathepsin K remain the most sensitive and specific markers of these neoplasms. Elevated expression of phosphorylated S6 in Xp11 translocation RCC suggests the mTOR pathway as an attractive potential therapeutic target for these neoplasms.
doi:10.1097/PAS.0b013e3181e8ce5b
PMCID: PMC3449149  PMID: 20679884
TFE3; renal cell carcinoma; biomarker
7.  Pathway Signature and Cellular Differentiation in Clear Cell Renal Cell Carcinoma 
PLoS ONE  2010;5(5):e10696.
Background
Clear cell renal cell carcinoma (ccRCC) is the most common kidney cancer. The purpose of this study is to define a biological pathway signature and a cellular differentiation program in ccRCC.
Methodology
We performed gene expression profiling of early-stage ccRCC and patient-matched normal renal tissue using Affymetrix HG-U133a and HG-U133b GeneChips combined with a comprehensive bioinformatic analyses, including pathway analysis. The results were validated by real time PCR and IHC on two independent sample sets. Cellular differentiation experiments were performed on ccRCC cell lines and their matched normal renal epithelial cells, in differentiation media, to determine their mesenchymal differentiation potential.
Principal Findings
We identified a unique pathway signature with three major biological alterations—loss of normal renal function, down-regulated metabolism, and immune activation–which revealed an adipogenic gene expression signature linked to the hallmark lipid-laden clear cell morphology of ccRCC. Culturing normal renal and ccRCC cells in differentiation media showed that only ccRCC cells were induced to undergo adipogenic and, surprisingly, osteogenic differentiation. A gene expression signature consistent with epithelial mesenchymal transition (EMT) was identified for ccRCC. We revealed significant down-regulation of four developmental transcription factors (GATA3, TFCP2L1, TFAP2B, DMRT2) that are important for normal renal development.
Conclusions
ccRCC is characterized by a lack of epithelial differentiation, mesenchymal/adipogenic transdifferentiation, and pluripotent mesenchymal stem cell-like differentiation capacity in vitro. We suggest that down-regulation of developmental transcription factors may mediate the aberrant differentiation in ccRCC. We propose a model in which normal renal epithelial cells undergo dedifferentiation, EMT, and adipogenic transdifferentiation, resulting in ccRCC. Because ccRCC cells grown in adipogenic media regain the characteristic ccRCC phenotype, we have indentified a new in vitro ccRCC cell model more resembling ccRCC tumor morphology.
doi:10.1371/journal.pone.0010696
PMCID: PMC2872663  PMID: 20502531
8.  Ortho-quinone-enhanced ascorbate oxidation. Combined roles of lipid charge and the magnesium cation 
Quinones are widely distributed compounds in nature. Of these, ortho-quinones are found to be involved in the pathogenic mechanism of Parkinson’s disease, in oxidative deaminations to free-radical redox reactions, and as intermediates in the pathways implicated in the carcinogenicity of 2,3- and 3,4-catechol estrogens. Addition of MgCl2 to solutions of the hydrophobic ortho-quinones, 1,10-phenanthroquinone (PHQ) and beta-lapachone (LQ) enhances ascorbate oxidation in the absence or presence of large unilamellar vesicles (LUVs) of the neutral lipid dimyristoylphos-phatidylcholine (DMPC), although initial rates of ascorbate oxidation are smaller in the presence of lipid as compared to its absence. Addition of this salt to solutions of the para-quinone 1,4-naphthoquinone (NQ) did not affect the ascorbate rate of oxidation in the absence or presence of DMPC. Addition of MgCl2 to semiquinone solutions of PHQ or LQ in the presence or absence of DMPC increases semiquinone stability, as detected from the semiquinone disproportionation equilibrium displacement to semiquinone formation. Furthermore, MgCl2 increases the partition of the ortho-semiquinones into the aqueous phase, although no such effect is observed for the semiquinone of NQ. For all the quinones under study, smaller rates of ascorbate oxidation and of semiquinone equilibrium concentration occur in the presence of negatively charged LUVs composed of an equimolar mixture of DMPC and dimyristoylphosphatidic acid DMPA. Ascorbate oxidation rate enhancements correlate with an increase in semiquinone concentration with addition of MgCl2, in the absence or presence of neutral lipid. This observation favors the proposition that ascorbate oxidation rate increases are caused by semiquinone thermodynamic stabilization. Thus, the ascorbate oxidation rate enhancement by MgCl2 in solutions containing hydrophobic ortho-quinones is still possible in systems with hydrophobic environments analogous to that of DMPC.
doi:10.1080/02772240701499778
PMCID: PMC2790193  PMID: 20011675
Ortho-quinone; semiquinone; magnesium; DMPC; membrane; ascorbate; DMPA; beta-lapachone; phenanthroquinone; naphthoquinone
9.  Whole lesion quantitative CT evaluation of renal cell carcinoma: differentiation of clear cell from papillary renal cell carcinoma 
SpringerPlus  2015;4:66.
Purpose
Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell cancer (RCC), followed by papillary RCC (pRCC). It is important to distinguish these two subtypes because of prognostic differences and possible changes in management, especially in cases undergoing active surveillance. The purpose of our study is to evaluate the use of voxel-based whole-lesion (WL) enhancement parameters on contrast enhanced computed tomography (CECT) to distinguish ccRCC from pRCC.
Materials and methods
In this institutional review board-approved study, we retrospectively queried the surgical database for post nephrectomy patients who had pathology proven ccRCC or pRCC and who had preoperative multiphase CECT of the abdomen between June 2009 and June 2011. A total of 61 patients (46 with ccRCC and 15 with pRCC) who underwent robotic assisted partial nephrectomy for clinically localized disease were included in the study. Multiphase CT acquisitions were transferred to a dedicated three-dimensional workstation, and WL regions of interest were manually segmented. Voxel-based contrast enhancement values were collected from the lesion segmentation and displayed as a histogram. Mean and median enhancement and histogram distribution parameters skewness, kurtosis, standard deviation, and interquartile range were calculated for each lesion. Comparison between ccRCC and pRCC was made using each imaging parameter. For mean and median enhancement, which had a normal distribution, independent t-test was used. For histogram distribution parameters, which were not normally distributed, Wilcoxon rank sum test was used.
Results
ccRCC had significantly higher mean and median whole WL enhancement (p < 0.01) compared to pRCC on arterial, nephrographic, and excretory phases. ccRCC had significantly higher interquartile range and standard deviation (p < 0.01) and significantly lower skewness (p < 0.01) compared to pRCC on arterial and nephrographic phases. ccRCC had significantly lower kurtosis compared to pRCC on only the arterial phase.
Conclusion
Our study suggests that voxel-based WL enhancement parameters can be used as a quantitative tool to differentiate ccRCC from pRCC. Differentiating between the two main types of RCC would provide the patient and the treating physicians more information to formulate the initial approach to managing the patient’s renal cancer.
doi:10.1186/s40064-015-0823-z
PMCID: PMC4325006
Whole lesion enhancement parameters; Papillary renal cell carcinoma; Clear cell renal cell carcinoma; Histogram analysis
10.  Discovery of Potent Small-Molecule Inhibitors of Multidrug-Resistant Plasmodium falciparum Using a Novel Miniaturized High-Throughput Luciferase-Based Assay ▿ †  
Malaria is a global health problem that causes significant mortality and morbidity, with more than 1 million deaths per year caused by Plasmodium falciparum. Most antimalarial drugs face decreased efficacy due to the emergence of resistant parasites, which necessitates the discovery of new drugs. To identify new antimalarials, we developed an automated 384-well plate screening assay using P. falciparum parasites that stably express cytoplasmic firefly luciferase. After initial optimization, we tested two different types of compound libraries: known bioactive collections (Library of Pharmacologically Active Compounds [LOPAC] and the library from the National Institute of Neurological Disorders and Stroke [NINDS]) and a library of uncharacterized compounds (ChemBridge). A total of 12,320 compounds were screened at 5.5 μM. Selecting only compounds that reduced parasite growth by 85% resulted in 33 hits from the combined bioactive collection and 130 hits from the ChemBridge library. Fifteen novel drug-like compounds from the bioactive collection were found to be active against P. falciparum. Twelve new chemical scaffolds were found from the ChemBridge hits, the most potent of which was a series based on the 1,4-naphthoquinone scaffold, which is structurally similar to the FDA-approved antimalarial atovaquone. However, in contrast to atovaquone, which acts to inhibit the bc1 complex and block the electron transport chain in parasite mitochondria, we have determined that our new 1,4-napthoquinones act in a novel, non-bc1-dependent mechanism and remain potent against atovaquone- and chloroquine-resistant parasites. Ultimately, this study may provide new probes to understand the molecular details of the malaria life cycle and to identify new antimalarials.
doi:10.1128/AAC.00431-10
PMCID: PMC2934977  PMID: 20547797
11.  Research consultation clinic: impetus towards facilitating primary care research 
Background
In Singapore, SingHealth Polyclinics (SHP) is an accredited Family Medicine (FM) training centre which managed 1.8 million primary care patient-visits in 2012. To promote research in the institution, research consultation clinics (RCC) are being introduced in 2010 to enable free face-to-face consultation between experienced and novice researchers on specific research topics. Each RCC session allows about an hour or more for the SHP staff, medical undergraduates and general practitioners to seek advice and clarification on key research areas, ranging from research question refinement, study design and execution, data analysis, result presentation to publication. The consultants comprise of two FM researchers with postgraduate research qualification.
Aim
This article aims to review the implementation of RCC from 2010 to 2012 and its impact on research activities and outcome indicators in the same period of time.
Methods
The study comprised of two segments. Part I was a three-year retrospective review of the RCC administrative record. The total number of RCC sessions, hours utilised, participants’ profiles, the number of research studies initiated by them and their research presentations at local and overseas scientific meetings/conferences were computed. Part 2 was an anonymous web-based questionnaire survey fielded to RCC participants to collect their feedback on the RCC service and their self-reported initiation and completion of research study after the RCC consultation.
Results
The RCC sessions increased from 17 to 40 sessions, resulting in increment of 2 to 14 research presentations and from 2 to 6 initiations of new research studies per annum from 2010–2012. The response rate to the questionnaire survey was 70.3%, with the majority of multi-disciplinary respondents rated the RCC service to be accessible, adequate and were satisfied with its quality. Study design, data management and study execution were ranked as important areas of research for consultation. 79% of them had started a research project and 36% had completed their studies.
Conclusions
The RCC is a feasible model to catalyse multi-disciplinary research in primary care institutions. Further study is needed to evaluate its relevance when research advances and novice researchers become experienced investigators to take on more complex projects.
doi:10.1186/1447-056X-12-4
PMCID: PMC3848628  PMID: 24041268
Research; Consultation; Primary care
12.  VX680/MK-0457, a potent and selective Aurora kinase inhibitor, targets both tumor and endothelial cells in clear cell renal cell carcinoma 
Aurora kinases are key regulators of cell mitosis and have been implicated in the process of tumorigenesis. In recent years, the Aurora kinases have attracted much interest as promising targets for cancer treatment. Here we report on the roles of Aurora A and Aurora B kinases in clear cell renal cell carcinoma (ccRCC). Using genomewide expression array analysis of 174 patient samples of ccRCC, we found that expression levels of Aurora A and B were significantly elevated in ccRCC compared to normal kidney samples. High expression levels of Aurora A and Aurora B were significantly associated with advanced tumor stage and poor patient survival. Inhibition of Aurora kinase activity with the drug VX680 (also referred to as MK-0457) inhibited ccRCC cell growth in vitro and led to ccRCC cell accumulation in the G2/M phase and apoptosis. Growth of ccRCC xenograft tumors was also inhibited by VX680 treatment, accompanied by a reduction of tumor microvessel density. Analysis of endothelial cell lines demonstrated that VX680 inhibits endothelial cell growth with effects similar to that seen in ccRCC cells. Our findings suggest that VX680 inhibits the growth of ccRCC tumors by targeting the proliferation of both ccRCC tumor cells and tumor-associated endothelial cells. Aurora kinases and their downstream cell cycle proteins have an important role in ccRCC and may be potent prognostic markers and therapy targets for this disease.
PMCID: PMC2892409  PMID: 20589168
Aurora kinase; Aurora; renal cell carcinoma; VX680; MK-0457
13.  CpG methylation profiling in VHL related and VHL unrelated renal cell carcinoma 
Molecular Cancer  2009;8:31.
Background
Renal cell carcinoma (RCC) is histopathologically heterogeneous with clear cell and papillary the most common subtypes. The most frequent molecular abnormality in clear cell RCC is VHL inactivation but promoter methylation of tumour suppressor genes is common in both subtypes of RCC. To investigate whether RCC CpG methylation status was influenced by histopathology and VHL status we performed high-throughput epigenetic profiling using the Illumina Goldengate Methylation Array in 62 RCC (29 RCC from von Hippel-Lindau (VHL) disease patients, 20 sporadic clear cell RCC with wild type VHL and 13 sporadic papillary RCC).
Results
43 genes were methylated in >20% of primary RCC (range 20–45%) and most (37/43) of these had not been reported previously to be methylated in RCC. The distribution of the number of methylated CpGs in individual tumours differed from the expected Poisson distribution (p < 0.00001; log-likelihood G test) suggesting that a subset of RCC displayed a CpG Island Methylator Phenotype. Comparison of RCC subtypes revealed that, on average, tumour specific CpG methylation was most prevalent in papillary RCC and least in VHL RCC. Many of the genes preferentially methylated in pRCC were linked to TGFβ or ERK/Akt signalling.
Conclusion
These findings demonstrate differing patterns of tumour-specific CpG methylation in VHL and non VHL clear cell RCC and papillary RCC, and identify multiple novel potential CpG methylation biomarkers for RCC.
doi:10.1186/1476-4598-8-31
PMCID: PMC2698845  PMID: 19493342
14.  Comparison of estrogen-derived ortho-quinone and para-quinol concerning induction of oxidative stress 
Ortho-quinones formed from catechol estrogens are considered prooxidants due to the production of superoxide radical anions through redox cycling via semiquinones. Para-quinols have been identified as novel metabolites of and as the major products of hydroxyl-radical scavenging by estrogens. Cycling of these compounds has also been discovered, because they are converted back to the parent estrogen via reductive aromatization in vitro and in vivo. We hypothesized that, unlike ortho-quinones, para-quinols do not induce oxidative stress due to this cycling. Like the estrogen itself, the 17β-estradiol-derived para-quinol (10β,17β-dihydroxyestra-1,4-diene-3-one) did not induce oxidative stress, as the rate of hydrogen peroxide production during the incubations of the compounds in various tissue homogenates was not significantly different from that of the control experiments performed without the addition of a test compound. We also confirmed that the estrogen metabolite estra-1,5(10)-dien-3,4,17-trione (estrone 3,4-quinone) was a profound prooxidant due to redox cycling, especially in uterine tissue. Therefore, we concluded that para-quinols do not induce oxidative stress.
doi:10.1016/j.jsbmb.2006.11.025
PMCID: PMC2752863  PMID: 17582759
15.  Overexpression of FoxM1 is associated with tumor progression in patients with clear cell renal cell carcinoma 
Background
Fork head box M1 (FoxM1) is a proliferation-associated transcription factor essential for cell cycle progression. Numerous studies have documented that FoxM1 has multiple functions in tumorigenesis and its elevated levels are frequently associated with cancer progression. The present study was conducted to investigate the expression of FoxM1 and its prognostic significance in clear cell renal cell carcinoma (ccRCC). Meanwhile, the function of FoxM1 in human ccRCC was further investigated in cell culture models.
Methods
Real-time quantitative PCR, western blot and immunohistochemistry were used to explore FoxM1 expression in ccRCC cell lines and primary ccRCC clinical specimens. FoxM1 expression was knocked down by small interfering RNA (siRNA) in Caki-1 and 786-O cells; proliferation, colony formation, cell cycle, migration, invasion, and angiogenesis were assayed.
Results
FoxM1 expression was up-regulated in the majority of the ccRCC clinical tissue specimens at both mRNA and protein levels. Clinic pathological analysis showed that FoxM1 expression was significantly correlated with primary tumor stage (P <0.001), lymph node metastasis (P = 0.01), distant metastasis (P = 0.01), TNM stage (P < 0.001) and histological grade (P = 0.003). The Kaplan–Meier survival curves revealed that high FoxM1 expression was associated with poor prognosis in ccRCC patients (P < 0.001). FoxM1 expression was an independent prognostic marker of overall ccRCC patient survival in a multivariate analysis (P = 0.008). Experimentally, we found that down-regulation of FoxM1 inhibited cell proliferation and induced cell cycle arrest with reduced expression of cyclin B1, cyclin D1, and Cdk2, and increased expression of p21 and p27. Also, down-regulation of FoxM1 reduced expression and activity of matrix metalloproteinase-2 (MMP-2), MMP-9 and vascular endothelial growth factor (VEGF), resulting in the inhibition of migration, invasion, and angiogenesis.
Conclusions
These results suggest that FoxM1 expression is likely to play important roles in ccRCC development and progression, and that FoxM1 is a prognostic biomarker and a promising therapeutic target for ccRCC.
doi:10.1186/1479-5876-10-200
PMCID: PMC3492118  PMID: 23006512
Renal cell carcinoma; FoxM1; Prognosis; Small interfering RNA
16.  A HIF-regulated VHL-PTP1B-Src signaling axis identifies a therapeutic target in Renal Cell Carcinoma 
Science Translational Medicine  2011;3(85):85ra47.
Metastatic renal cell carcinoma (RCC) is a molecularly heterogeneous disease that is intrinsically resistant to chemotherapy and radiotherapy. While VEGF and mTOR targeted therapies have shown clinical activity, their effects are variable and short-lived, underscoring the need for improved treatment strategies for RCC. Here, we used quantitative phosphoproteomics and immunohistochemical profiling of 346 RCC specimens to determine that Src kinase signaling is elevated in RCC cells that retain wild type (WT) von Hippel-Lindau (VHL) protein expression. Correspondingly, VHL-WT RCC cell lines and xenografts were sensitized to the Src inhibitor dasatinib compared to VHL null cells. Forced expression of hypoxia inducible factor (HIF) in VHL-WT RCC cells diminished Src signaling output by repressing transcription of the Src activator protein tyrosine phosphatase 1B (PTP1B) and conferred resistance to dasatinib. Our results suggest that a HIF-regulated VHL-PTP1B-Src signaling axis determines sensitivity of RCC to Src inhibitors and that stratification of RCC patients using antibody-based biomarker profiling may identify patients likely to respond to Src inhibitors in RCC clinical trials.
doi:10.1126/scitranslmed.3002004
PMCID: PMC3303496  PMID: 21632985
17.  Axitinib for the Management of Metastatic Renal Cell Carcinoma 
Drugs in R&d  2012;11(2):113-126.
In recent years, targeted agents have changed the treatment landscape for patients with advanced renal cell carcinoma (RCC), greatly improving treatment outcomes. Several targeted agents are now licensed for the treatment of metastatic RCC (mRCC), and a number of new agents are under investigation. Axitinib, a small molecule indazole derivative is an oral, potent multitargeted tyrosine kinase receptor inhibitor, which selectively inhibits vascular endothelial growth factor receptors (VEGFR)-1, -2, and -3 at subnanomolar concentrations, in vitro. In various nonclinical models, axitinib has demonstrated in vivo target modulation and antiangiogenesis. In pharmacokinetic studies, axitinib administered orally with food at the proposed regimen of 5mg twice daily continuous daily dosing, is rapidly absorbed, reaching peak concentrations within 2–6 hours. Axitinib is metabolized primarily in the liver via the cytochrome P450 (CYP) system with less than 1% of the administered drug passing unchanged in the urine. The pharmacokinetics of axitinib do not appear to be altered by coadministered chemotherapies, and antacids do not have a clinically significant effect. However, coadministration with CYP3A4 and 1A2 inducers is contraindicated. In addition, proton pump inhibitors reduce the rate of axitinib absorption. Increased axitinib exposure is associated with higher efficacy indicated by decreased tumor perfusion and volume. In three phase II clinical trials in patients with advancedRCCpreviously treated with cytokines, chemotherapy or targeted agents, axitinib has demonstrated antitumor activity with a favorable noncumulative toxicity profile. In one study of Western patients with cytokine-refractory mRCC, an objective response rate (ORR) of 44.2% (95% CI 30.5, 58.7) was achieved. The median time to progression was 15.7 months (95%CI 8.4, 23.4) and the median overall survival (OS) was 29.9 months (95%CI 20.3, not estimable). In the second study of patients with sorafenib-refractory mRCC, ORR was 22.6% (95% CI 12.9, 35.0). The median progression-free survival (PFS) was 7.4 months (95% CI 6.7, 11.0) and a median OS of 13.6 months (95% CI 8.4, 18.8) was achieved. Results from the third study in Japanese patients with cytokine-refractory mRCC reported an ORR of 55% and median PFS of 12.9 months (95% CI 9.8, 15.6).
In the three studies, themost common adverse events reported were fatigue, hypertension, hand-foot syndrome (HFS), and gastrointestinal toxicity, which were generally manageable with standard medical intervention. Of note, the incidence of HFS and proteinuria in the Japanese study was higher than that reported in the Western study in cytokine-refractory mRCC patients.
An observed association between diastolic blood pressure ≥90 mmHg and increased efficacy suggests potential use as a prognostic biomarker. However, this requires further investigation. Two randomized phase III clinical trials are ongoing to determine the efficacy of axitinib in patients with mRCC in the first- and second-line setting. These results will help to determine the place of axitinib in the mRCC treatment algorithm.
doi:10.2165/11591240-000000000-00000
PMCID: PMC3585900  PMID: 21679004
18.  EMMPRIN Promotes Angiogenesis, Proliferation, Invasion and Resistance to Sunitinib in Renal Cell Carcinoma, and Its Level Predicts Patient Outcome 
PLoS ONE  2013;8(9):e74313.
Purpose
Extracellular matrix metalloproteinase inducer (EMMPRIN) has been reported to play crucial roles, including in angiogenesis, in several carcinomas. However, the correlation between EMMPRIN levels and angiogenesis expression profile has not been reported, and the role of EMMPRIN in renal cell carcinoma (RCC) is unclear. In the present study, we evaluated the association of EMMPRIN with angiogenesis, its value in prognosis, and its roles in RCC.
Experimental Design
EMMPRIN expression was examined in 50 RCC patients treated with radical nephrectomy. Angiogenesis, proliferation, and invasion activity were evaluated using EMMPRIN knockdown RCC cell lines. The size of EMMPRIN-overexpressing xenografts was measured and the degree of angiogenesis was quantified. EMMPRIN expression was evaluated in RCC patients who received sunitinib therapy and in sunitinib-resistant cells. Further, the relation between EMMPRIN expression and sensitivity to sunitinib was examined.
Results
EMMPRIN score was significantly associated with clinicopathological parameters in RCC patients, as well as being significantly correlated with microvessel area (MVA) in immature vessels and with prognosis. Down-regulation of EMMPRIN by siRNA led to decreased VEGF and bFGF expression, cell proliferation, and invasive potential. EMMPRIN over-expressing xenografts showed accelerated growth and MVA of immature vessels. EMMPRIN expression was significantly increased in patients who received sunitinib therapy as well as in sunitinib-resistant 786-O cells (786-suni). EMMPRIN-overexpressing RCC cells were resistant to sunitinib.
Conclusion
Our findings indicate that high expression of EMMPRIN in RCC plays important roles in tumor progression and sunitinib resistance. Therefore, EMMPRIN could be a novel target for the treatment of RCC.
doi:10.1371/journal.pone.0074313
PMCID: PMC3779201  PMID: 24073208
19.  Axitinib for the Management of Metastatic Renal Cell Carcinoma 
Drugs in R&D  2012;11(2):113-126.
In recent years, targeted agents have changed the treatment landscape for patients with advanced renal cell carcinoma (RCC), greatly improving treatment outcomes. Several targeted agents are now licensed for the treatment of metastatic RCC (mRCC), and a number of new agents are under investigation. Axitinib, a small molecule indazole derivative is an oral, potent multitargeted tyrosine kinase receptor inhibitor, which selectively inhibits vascular endothelial growth factor receptors (VEGFR)-1, -2, and -3 at subnanomolar concentrations, in vitro. In various nonclinical models, axitinib has demonstrated in vivo target modulation and antiangiogenesis. In pharmacokinetic studies, axitinib administered orally with food at the proposed regimen of 5mg twice daily continuous daily dosing, is rapidly absorbed, reaching peak concentrations within 2–6 hours. Axitinib is metabolized primarily in the liver via the cytochrome P450 (CYP) system with less than 1% of the administered drug passing unchanged in the urine. The pharmacokinetics of axitinib do not appear to be altered by coadministered chemotherapies, and antacids do not have a clinically significant effect. However, coadministration with CYP3A4 and 1A2 inducers is contraindicated. In addition, proton pump inhibitors reduce the rate of axitinib absorption. Increased axitinib exposure is associated with higher efficacy indicated by decreased tumor perfusion and volume. In three phase II clinical trials in patients with advancedRCCpreviously treated with cytokines, chemotherapy or targeted agents, axitinib has demonstrated antitumor activity with a favorable noncumulative toxicity profile. In one study of Western patients with cytokine-refractory mRCC, an objective response rate (ORR) of 44.2% (95% CI 30.5, 58.7) was achieved. The median time to progression was 15.7 months (95%CI 8.4, 23.4) and the median overall survival (OS) was 29.9 months (95%CI 20.3, not estimable). In the second study of patients with sorafenib-refractory mRCC, ORR was 22.6% (95% CI 12.9, 35.0). The median progression-free survival (PFS) was 7.4 months (95% CI 6.7, 11.0) and a median OS of 13.6 months (95% CI 8.4, 18.8) was achieved. Results from the third study in Japanese patients with cytokine-refractory mRCC reported an ORR of 55% and median PFS of 12.9 months (95% CI 9.8, 15.6).
In the three studies, themost common adverse events reported were fatigue, hypertension, hand-foot syndrome (HFS), and gastrointestinal toxicity, which were generally manageable with standard medical intervention. Of note, the incidence of HFS and proteinuria in the Japanese study was higher than that reported in the Western study in cytokine-refractory mRCC patients.
An observed association between diastolic blood pressure ≥90 mmHg and increased efficacy suggests potential use as a prognostic biomarker. However, this requires further investigation. Two randomized phase III clinical trials are ongoing to determine the efficacy of axitinib in patients with mRCC in the first- and second-line setting. These results will help to determine the place of axitinib in the mRCC treatment algorithm.
doi:10.2165/11591240-000000000-00000
PMCID: PMC3585900  PMID: 21679004
20.  Identification of Molecular Tumor Markers in Renal Cell Carcinomas with TFE3 Protein Expression by RNA Sequencing12 
Neoplasia (New York, N.Y.)  2013;15(11):1231-1240.
TFE3 translocation renal cell carcinoma (tRCC) is defined by chromosomal translocations involving the TFE3 transcription factor at chromosome Xp11.2. Genetically proven TFE3 tRCCs have a broad histologic spectrum with overlapping features to other renal tumor subtypes. In this study, we aimed for characterizing RCC with TFE3 protein expression. Using next-generation whole transcriptome sequencing (RNA-Seq) as a discovery tool, we analyzed fusion transcripts, gene expression profile, and somatic mutations in frozen tissue of one TFE3 tRCC. By applying a computational analysis developed to call chimeric RNA molecules from paired-end RNA-Seq data, we confirmed the known TFE3 translocation. Its fusion partner SFPQ has already been described as fusion partner in tRCCs. In addition, an RNA read-through chimera between TMED6 and COG8 as well as MET and KDR (VEGFR2) point mutations were identified. An EGFR mutation, but no chromosomal rearrangements, was identified in a control group of five clear cell RCCs (ccRCCs). The TFE3 tRCC could be clearly distinguished from the ccRCCs by RNA-Seq gene expression measurements using a previously reported tRCC gene signature. In validation experiments using reverse transcription-PCR, TMED6-COG8 chimera expression was significantly higher in nine TFE3 translocated and six TFE3-expressing/non-translocated RCCs than in 24 ccRCCs (P < .001) and 22 papillary RCCs (P < .05–.07). Immunohistochemical analysis of selected genes from the tRCC gene signature showed significantly higher eukaryotic translation elongation factor 1 alpha 2 (EEF1A2) and Contactin 3 (CNTN3) expression in 16 TFE3 translocated and six TFE3-expressing/non-translocated RCCs than in over 200 ccRCCs (P < .0001, both).
PMCID: PMC3859447  PMID: 24339735
21.  DNA cleavage by hydroxy-salicylidene-ethylendiamine-iron complexes. 
Nucleic Acids Research  1999;27(21):4160-4166.
Bis(hydroxy)salen.Fe complexes were designed as self-activated chemical nucleases. The presence of a hy-droxyl group on the two salicylidene moieties serve to form a hydroquinone system cooperating with the iron redox system to facilitate spontaneous formation of free radicals. We compared the DNA binding and cleaving properties of the ortho -, meta- and para -(bishydroxy) salen.Fe complexes with that of the corresponding chelate lacking the hydroxyl groups. DNA melting temperature studies indicated that the para complex exhibits the highest affinity for DNA. In addition, this para compound was considerably more potent at cleaving supercoiled plasmid DNA than the regio-isomeric ortho - and meta -hydroxy-salen.Fe complexes, even in the absence of a reducing agent, such as dithiothreitol used to activate the metal complex. The DNA cleaving activity of the para isomer is both time and concentration dependent and the complexed iron atom is absolutely essential for the sequence uniform cleavage of DNA. From a mechanistic point of view, electron spin resonance measurements suggest that DNA contributes positively to the activation of the semi-quinone system and the production of ligand radical species responsible for subsequent strand scission in the absence of a reducing agent. The para -hydroxy-salen.Fe complex has been used for detecting sequence-specific drug-DNA interactions. Specific binding of Hoechst 33258 to AT sequences and chromomycin to GC sequences were shown. The para -bis(hydroxy)salen.Fe derivative complements the tool box of footprinting reagents which can be utilised to produce efficient cleavage of DNA.
PMCID: PMC148689  PMID: 10518606
22.  Ovatodiolide Targets β-Catenin Signaling in Suppressing Tumorigenesis and Overcoming Drug Resistance in Renal Cell Carcinoma 
Dysregulated β-catenin signaling is intricately involved in renal cell carcinoma (RCC) carcinogenesis and progression. Determining potential β-catenin signaling inhibitors would be helpful in ameliorating drug resistance in advanced or metastatic RCC. Screening for β-catenin signaling inhibitors involved in silico inquiry of the PubChem Bioactivity database followed by TCF/LEF reporter assay. The biological effects of ovatodiolide were evaluated in 4 RCC cell lines in vitro and 2 RCC cell lines in a mouse xenograft model. The synergistic effects of ovatodiolide and sorafenib or sunitinib were examined in 2 TKI-resistant RCC cell lines. Ovatodiolide, a pure compound of Anisomeles indica, inhibited β-catenin signaling and reduced RCC cell viability, survival, migration/invasion, and in vitro cell or in vivo mouse tumorigenicity. Cytotoxicity was significantly reduced in a normal kidney epithelial cell line with the treatment. Ovatodiolide reduced phosphorylated β-catenin (S552) that inhibited β-catenin nuclear translocation. Moreover, ovatodiolide decreased β-catenin stability and impaired the association of β-catenin and transcription factor 4. Ovatodiolide combined with sorafenib or sunitinib overcame drug resistance in TKI-resistant RCC cells. Ovatodiolide may be a potent β-catenin signaling inhibitor, with synergistic effects with sorafenib or sunitinib, and therefore, a useful candidate for improving RCC therapy.
doi:10.1155/2013/161628
PMCID: PMC3677612  PMID: 23781255
23.  Papillary Renal Cell Carcinoma is Associated with PTEN Hamartoma Tumor Syndrome 
Urology  2012;79(5):1187.e1-1187.e7.
Objectives
To formally study the prevalence and histological classification of renal cell carcinoma (RCC) in a series of patients with PTEN Hamartoma Tumor syndrome (PHTS).
Methods
We evaluated prevalence of RCC within a prospectively-accrued series of 219 patients found to have pathogenic germline PTEN mutations. Clinical data including pathology reports were requested for all participants. Slides and tumor blocks were requested for central pathology re-review and immunohistochemistry (IHC) analysis.
Results
Nine patients were identified with RCC. Based on SEER data 0.28 RCC cases were expected for the group, giving an overall age-adjusted Standardized Incidence Ratio (SIR) of 31.7 (95% CI 15.4–58.1, p<0.001) with a higher sex-adjusted SIR for females (46.7 vs. 21.6 for males). Reported histology of each mutation positive patient’s RCC was variable. However, on central pathology re-review of 8 patients, six examined lesions were determined to be of papillary subhistology (pRCC), with the other two patients’ tumors consistent with the initial report of chromophobe RCC (chRCC). IHC demonstrated complete loss of PTEN protein in all PTEN mutation positive patients’ pRCCs and patchy positivity in one chRCC.
Conclusions
PHTS is a hereditary syndrome newly associated with pRCC, and PTEN IHC may be a helpful screening tool to identify pRCC patients with PHTS. Physicians caring for PHTS patients should note the >31-fold increased risk for RCC and have a low threshold for investigating possible RCC in patients with relevant complaints. Renal ultrasound is not sensitive for detecting pRCC and so PHTS patients should have alternate renal imaging (CT or MRI).
doi:10.1016/j.urology.2011.12.025
PMCID: PMC3341468  PMID: 22381246
PTEN germline mutations; Cowden syndrome; Bannayan-Riley-Ruvalcaba syndrome; Carcinoma, Kidney
24.  Multiple biomarker tissue arrays: A computational approach to identifying protein-protein interactions in the EGFR/ERK signalling pathway 
Background
Many studies have demonstrated genetic and environmental factors that lead to renal cell carcinoma (RCC) and that occur during a protracted period of tumourigenesis. It appears suitable to identify and characterise potential molecular markers that appear during tumourigenesis and that might provide rapid and effective possibilities for the early detection of RCC. EGFR activation induces cell cycle progression, inhibition of apoptosis and angiogenesis, promotion of invasion/metastasis, and other tumour promoting activities. Over-expression of EGFR is thought to play an important role in tumour initiation and progression of RCC because up-regulation of EGFR has been associated with high grade cancers and a worse prognosis.
Methods
Characterisation of the protein profile interacting with EGFR was performed using the following: an immunohistochemical (IHC) study of EGFR, a comprehensive computational study of EGFR protein-protein interactions, an analysis correlating the expression levels of EGFR with other significant markers in the tumourigenicity of RCC, and finally, an analysis of the utility of EGFR for prognosis in a cohort of patients with renal cell carcinoma.
Results
The cases that showed a higher level of this protein fell within the clear cell histological subtype (p = 0.001). The EGFR significance statistic was found with respect to a worse prognosis. In vivo significant correlations were found with PDGFR-β, Flk-1, Hif1-α, proteins related to differentiation (such as DLL3 and DLL4 ligands), and certain metabolic proteins such as Glut5. In silico significant associations gave us a panel of 32 EGFR-interacting proteins (EIP) using the APID and STRING databases.
Conclusions
This work summarises the multifaceted role of EGFR in the pathology of RCC, and it identifies EIPs that could help to provide mechanistic explanations for the different behaviours observed in tumours.
doi:10.1186/1750-2187-7-14
PMCID: PMC3493339  PMID: 22937740
EGFR; Interacting proteins; Renal cell carcinoma; Tissue array
25.  Tumor suppressive microRNA-1285 regulates novel molecular targets: Aberrant expression and functional significance in renal cell carcinoma 
Oncotarget  2012;3(1):44-57.
MicroRNAs (miRNA) are non-coding RNAs, approximately 22 nucleotides in length, which function as post-transcriptional regulators. A large body of evidence indicates that miRNAs regulate the expression of cancer-related genes involved in proliferation, migration, invasion, and metastasis. The aim of this study was to identify novel cancer networks in renal cell carcinoma (RCC) based on miRNA expression signatures obtained from RCC clinical specimens. Expression signatures revealed that 103 miRNAs were significantly downregulated (< 0.5-fold change) in RCC specimens. Functional screening (cell proliferation assays) was performed to identify tumor suppressive activities of 20 downregulated miRNAs. Restoration of mature miRNAs in cancer cells showed that 14 miRNAs (miR-1285, miR-206, miR-1, miR-135a, miR-429, miR-200c, miR-1291, miR-133b, miR-508-3p, miR-360-3p, miR-509-5p, miR-218, miR-335, miR-1255b and miR-1285) markedly inhibited cancer cell proliferation, suggesting that these miRNAs were candidate tumor suppressive miRNAs in RCC. We focused on miR-1285 because it significantly inhibited cancer cell proliferation, invasion, and migration following its transfection. We addressed miR-1285-regulated cancer networks by using genome-wide gene expression analysis and bioinformatics. The data showed that transglutaminase 2 (TGM2) was directly regulated by miR-1285. Silencing of the target gene demonstrated significant inhibition of cell proliferation and invasion in the RCC cells. Furthermore, immunohistochemistry showed that TGM2 expression levels in RCC specimens were significantly higher than those in normal renal tissues. Downregulation of tumor suppressive miR-1285, which targets oncogenic genes including TGM2, might contribute to RCC development. Thus, miR-1285 modulates a novel molecular target and provides new insights into potential mechanisms of RCC oncogenesis.
PMCID: PMC3292891  PMID: 22294552
microRNA; expression signature; miR-1285; tumor suppressor; renal cell carcinoma; transglutaminase 2

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