The huge amount of transcript data produced by high-throughput sequencing requires the development and implementation of suitable bioinformatic workflows for their analysis and interpretation. These analysis workflows, including different modules, should be specifically designed also based on the sequencing platform (Roche 454, Illumina, SOLiD) and the nature of the data (polyA or total RNA fraction, strand specificity). In the case of cDNA obtained from a total RNA preparation, in addition to polyadenylated protein coding mRNAs, a great variety of transcript sequences can be obtained, including ribosomal RNAs, mitochondrial transcripts and a large variety of functional non coding RNAs (ncRNAs). To deal with these data the analysis workflow should include specific modules to distinguish ncRNAs fractions from the large number of other functional proteincoding transcripts. To this aim we developed an analysis pipeline that, given as input a large collection of reads (particularly from Roche 454), provides the expression profile at qualitative and quantitative level of human mtDNA, ribosomal RNAs, ncRNAs and protein coding mRNAs.

Recent studies have demonstrated an unexpected complexity of transcription in eukaryotes.Indeed the majority of the genome is transcribed and only a little fraction of these transcripts isannotated as protein coding genes and their splice variants. Therefore high throughput transcriptomesequencing continuously identifies novel RNAs and novel classes of RNAs, which are the result ofantisense, overlapping and non-coding RNA expression, demonstrating that the transcriptomecaptures a level of complexity that the simple genome sequence may not (1).Among next-generation sequencing platforms, the latest series of Roche 454 GS Sequencer, the GSFLX Titanium FLX+, allows to obtain in each run over a million reads, each with a length up to 700base. Sequences of such length, providing connectivity information among splicing sites, in additionto enabling accurate mapping and relative quantification of mRNAs, are particularly suitable for thecharacterization of full-length splicing variants that may be differently expressed inphysiopathological conditions (2). On the other hand the higher throughput of the Illumina HiSeq1000 (150 bp) and ABI SOLID (75 bp) platforms, makes them particularly suitable for transcriptslevel quantification and for small RNAs sequencing.Irrespectively of the NGS platform used, the first step required for transcriptome sequencing is theconstruction of a cDNA library. Several protocols have been developed so far to this aim and eachof them is suitable for sequencing on a specific platform exclusively.Here we describe a new fast and simple method (Patent pending RM2010A000293-PCT/IB2011/052369) to prepare and amplify a representative and strand-specific cDNA librarystarting from low input total RNA (500ng) for RNA-Seq applications, that may be implemented withall major platforms currently available (Roche 454, Illumina, ABI/Solid).Our method includes the following steps: a) rRNA removal from total RNA b) retrotranscription ofthe rRNA-depleted RNA to cDNA with 5' phosphorylated Tag-random-octamers custom designedcapable of preserving strand information; c) single-strand cDNAs purification; d) ligation andamplification of the purified cDNAs, thus obtaining high yield of concatamers around 20kb long.These DNA molecules can be equally sequenced both with Illumina and Roche 454 sequencingplatforms allowing not only the quantitative but also the qualitative assessment of the transcriptomecomplexity.Moreover, we developed a suitable bioinformatic pipeline for the analysis of the sequences producedupon application of this protocol. Indeed, we developed an in house python script, named Tag_Find(available upon request), able to recognize the position and the type of tag found within the readsequence. The program returns out two files, one containing the type of tags found and their readspositions and one fastq file with non-tagged reads, cleaned up from tags. The Tag_Find efficiency

Recent studies have demonstrated an unexpected complexity of transcription in eukaryotes. The majority of the genome is transcribed and only a little fraction of these transcripts is annotated as protein coding genes and their splice variants. Indeed, most transcripts are the result of antisense, overlapping and non-coding RNA expression. In this frame, one of the key aims of high throughput transcriptome sequencing is the detection of all RNA species present in the cell and the first crucial step for RNA-seq users is represented by the choice of the strategy for cDNA library construction. The protocols developed so far provide the utilization of the entire library for a single sequencing run with a specific platform.ResultsWe set up a unique protocol to generate and amplify a strand-specific cDNA library representative of all RNA species that may be implemented with all major platforms currently available on the market (Roche 454, Illumina, ABI/SOLiD). Our method is reproducible, fast, easy-to-perform and even allows to start from low input total RNA. Furthermore, we provide a suitable bioinformatics tool for the analysis of the sequences produced following this protocol.ConclusionWe tested the efficiency of our strategy, showing that our method is platform-independent, thus allowing the simultaneous analysis of the same sample with different NGS technologies, and providing an accurate quantitative and qualitative portrait of complex whole transcriptomes.

The Dlx and Msx homeodomain transcription factors play important roles in the control of limb development. The combined disruption of Msx1 and Msx2, as well as that of Dlx5 and Dlx6, lead to limb patterning defects with anomalies in digit number and shape. Msx1;Msx2 double mutants are characterized by the loss of derivatives of the anterior limb mesoderm which is not observed in either of the simple mutants. Dlx5;Dlx6 double mutants exhibit hindlimb ectrodactyly. While the morphogenetic action of Msx genes seems to involve the BMP molecules, the mode of action of Dlx genes still remains elusive. Here, examining the limb phenotypes of combined Dlx and Msx mutants we reveal a new Dlx-Msx regulatory loop directly involving BMPs. In Msx1;Dlx5;Dlx6 triple mutant mice (TKO), beside the expected ectrodactyly, we also observe the hallmark morphological anomalies of Msx1;Msx2 double mutants suggesting an epistatic role of Dlx5 and Dlx6 over Msx2. In Msx2;Dlx5;Dlx6 TKO mice we only observe an aggravation of the ectrodactyly defect without changes in the number of the individual components of the limb. Using a combination of qPCR, ChIP and bioinformatic analyses, we identify two Dlx/Msx regulatory pathways: 1) in the anterior limb mesoderm a non-cell autonomous Msx-Dlx regulatory loop involves BMP molecules through the AER and 2) in AER cells and, at later stages, in the limb mesoderm the regulation of Msx2 by Dlx5 and Dlx6 occurs also cell autonomously. These data bring new elements to decipher the complex AER-mesoderm dialogue that takes place during limb development and provide clues to understanding the etiology of congenital limb malformations.

Currently, there is very little information available regarding the microbiome associated with the wine production chain. Here, we used an amplicon sequencing approach based on high-throughput sequencing (HTS) to obtain a comprehensive assessment of the bacterial community associated with the production of three Apulian red wines, from grape to final product. The relationships among grape variety, the microbial community, and fermentation was investigated. Moreover, the winery microbiota was evaluated compared to the autochthonous species in vineyards that persist until the end of the winemaking process. The analysis highlighted the remarkable dynamics within the microbial communities during fermentation. A common microbial core shared among the examined wine varieties was observed, and the unique taxonomic signature of each wine appellation was revealed. New species belonging to the genus Halomonas were also reported. This study demonstrates the potential of this metagenomic approach, supported by optimized protocols, for identifying the biodiversity of the wine supply chain. The developed experimental pipeline offers new prospects for other research fields in which a comprehensive view of microbial community complexity and dynamics is desirable.

Diet in human health is no longer simple nutrition but, in the light of recent findings, it might play a pivotal role on cell health status by modulating apoptosis, detoxification, and appropriate gene response to environmental stresses. Epidemiological studies suggest a role of fruits and vegetables in protection against several diseases, and nutrients have been demonstrated to alter gene expression by DNA methylation and histone modifications [1-2]. Diet has also been found to modulate micro RNA (miRNA) expression, leading to a subsequent regulation of the effectors genes [3]. Furthermore, recent studies demonstrate that some plant/food-derived microRNAs (miRNAs) regulate gene expression in a sequence specific manner [4]. On the basis of all these findings, we have carried out a pilot study, using a combined "in-silico and wet" approach, to investigate the potential effects, and elucidate the molecular mechanisms, of edible plant miRNAs on the expression of human genes involved in cancer onset and progression. In the present paper we report the results obtained by transfecting 2 colon cancer cell lines, p53 wild type and p53 knock-out, with selected miRNAs of G. max, Z. mais and M. truncatula, which we found, by in silico analysis, to have a putative targeting activity on human oncogenes and tumor suppressor genes.

Mitochondrial biogenesis is an orchestrated process that presides to the regulation of the organelles homeostasis within a cell. We show that ?-rays, at doses commonly used in the radiation therapy for cancer treatment, induce an increase in mitochondrial mass and function, in response to a genotoxic stress that pushes cells into senescence, in the presence of a functional p53. Although the main effector of the response to ?-rays is the p53-p21 axis, we demonstrated that mitochondrial biogenesis is only indirectly regulated by p53, whose activation triggers a murine double minute 2 (MDM2)-mediated hypoxia-inducible factor 1? (HIF1?) degradation, leading to the release of peroxisome-proliferator activated receptor gamma co-activator 1? inhibition by HIF1?, thus promoting mitochondrial biogenesis. Mimicking hypoxia by HIF1? stabilization, in fact, blunts the mitochondrial response to ?-rays as well as the induction of p21-mediated cell senescence, indicating prevalence of the hypoxic over the genotoxic response. Finally, we also show in vivo that post-radiotherapy mitochondrial DNA copy number increase well correlates with lack of HIF1? increase in the tissue, concluding this may be a useful molecular tool to infer the trigger of a hypoxic response during radiotherapy, which may lead to failure of activation of cell senescence.

Clear cell renal cell carcinoma (ccRCC) is the most common malignant renal epithelial tumor and also the most deadly. To identify molecular changes occurring in ccRCC, in the present study we performed a genome wide analysis of its entire complement of mRNAs. Gene and exon-level analyses were carried out by means of the Affymetrix Exon Array platform. To achieve a reliable detection of differentially expressed cassette exons we implemented a novel methodology that considered contiguous combinations of exon triplets and candidate differentially expressed cassette exons were identified when the expression level was significantly different only in the central exon of the triplet. More detailed analyses were performed for selected genes using quantitative RT-PCR and confocal laser scanning microscopy. Our analysis detected over 2,000 differentially expressed genes, and about 250 genes alternatively spliced and showed differential inclusion of specific cassette exons comparing tumor and non-tumoral tissues. We demonstrated the presence in ccRCC of an altered expression of the PTP4A3, LAMA4, KCNJ1 and TCF21 genes (at both transcript and protein level). Furthermore, we confirmed, at the mRNA level, the involvement of CAV2 and SFRP genes that have previously been identified. At exon level, among potential candidates we validated a differentially included cassette exon in DAB2 gene with a significant increase of DAB2 p96 splice variant as compared to the p67 isoform. Based on the results obtained, and their robustness according to both statistical analysis and literature surveys, we believe that a combination of gene/isoform expression signature may remarkably contribute, after suitable validation, to a more effective and reliable definition of molecular biomarkers for ccRCC early diagnosis, prognosis and prediction of therapeutic response.

MotivationAround 50% of all human tumours carry point mutations in the p53 tumour suppressor gene, which alter p53 DNA binding specificity. In tumours with p53 wild type, p53 is often rendered functionally inert by the inactivation of its positive modulators or by the activation of negative factors, which block p53 transcriptional activities [1]. We identified a new p53 direct target gene, TRIM8, belonging to the Tripartite Motif (TRIM) protein family, defined by the presence of a RING domain, one or two B-boxes and a Coiled-Coil region. We found that TRIM8 overexpression leads, through a positive feedback loop, to p53 stabilization and p53-mediated suppression of cell proliferation. In order to identify the pathways activated by TRIM8 leading to p53 stabilization we transiently transfected with TRIM8 the HCT116-p53 (wt) cell line, and sequenced the total transcriptome performing a NGS run on a 454 GS FLX platform. Here we report some statistics and the preliminary results of: i) reads mapping on the human genome and analysis of differential expressed genes; ii) functional analysis of differentially expressed genes. MethodTotal RNA was extracted from HCT116-p53 (wt) cell line 48h after transfection, depleted of rRNA, retro-transcribed, amplified and sequenced by using the pyrosequencer Roche GS FLX Titanium Series. Genome mapping, statistics and differential expression analyses were performed by using the "NGS-Trex" system (NGS Transcriptome profile Explorer) (Mignone F. et al., submitted), a automatic system designed for analyzing Next Generation Sequencing data generated from large-scale transcriptome studies. The overall procedure involves three steps: 1) creation of a project and upload of reads in a multi-fasta format; 2) reads mapping onto the reference genome after setup of appropriate parameters; 3) annotation of mapped reads; 3) data mining by using simple query forms. TRIM8 and FLAG data were submitted to NGS-Trex using default parameters that can briefly summarized as follows: reads were mapped onto human genome (min similarity 90% and min overlap 50 nt) discarding reads mapping onto more than 10 genomic regions. Mapped reads were compared to annotation to assign reads to genes and to identify new splice variants. Differentially expressed genes and splicing events were identified by computing a P-value associated to an hypergeometric distribution. Housekeeping genes were used to normalise reads count before identification of differentially expressed genes. The lists of genes showing a differential expression in the two samples were then analysed by using DAVID v(6.7), an integrated biological knowledgebase and analytic tools (text and pathway-mining tools) for large gene list functional annotation [2,3]. An additional analysis on TRIM8 and FLAG sequence samples was made for the detection and annotation of the ncRNA genome fraction. We used a bioinformatic analysis pipeline, developed by us, which is able to: 1) select ncRNA fro

Many evidences report that alternative splicing, the mechanism which produces mRNAs and proteins with different structures and functions from the same gene, is altered in cancer cells. Thus, the identification and characterization of cancer-specific splice variants may give large impulse to the discovery of novel diagnostic and prognostic tumour biomarkers, as well as of new targets for more selective and effective therapies.ResultsWe present here a genome-wide analysis of the alternative splicing pattern of human genes through a computational analysis of normal and cancer-specific ESTs from seventeen anatomical groups, using data available in AspicDB, a database resource for the analysis of alternative splicing in human. By using a statistical methodology, normal and cancer-specific genes, splice sites and cassette exons were predicted in silico. The condition association of some of the novel normal/tumoral cassette exons was experimentally verified by RT-qPCR assays in the same anatomical system where they were predicted. Remarkably, the presence in vivo of the predicted alternative transcripts, specific for the nervous system, was confirmed in patients affected by glioblastoma.ConclusionThis study presents a novel computational methodology for the identification of tumor-associated transcript variants to be used as cancer molecular biomarkers, provides its experimental validation, and reports specific biomarkers for glioblastoma.

A central role for mitochondrial dysfunctions has been proposed in the pathogenesis of Down syndrome (DS), a multifactorial disorder caused by trisomy of human chromosome 21. To explore whether and how abnormalities in mitochondrial energy metabolism are involved in DS pathogenesis, we investigated the catalytic properties, gene expression and protein levels of certain proteins involved in mitochondrial ATP synthesis such as ATPase, ADP/ATP translocator (ANT) and adenylate kinase (AK) in human skin fibroblasts from subjects with DS (DS-HSF) comparing them with euploid fibroblasts. In DS-HSF, we found a strong impairment of mitochondrial ATP synthesis due to a reduction in the catalytic efficiency of each of the investigated proteins. This impairment occurred in spite of unchanged gene expression and an increase in ANT and AK protein content, whereas the amount of ATPase subunits was selectively reduced. Interestingly, exposure of DS-HSF to dibutyryl-cAMP, a permanent derivative of cAMP, stimulated ANT, AK and ATPase activities whereas H89, a specific PKA inhibitor, suppressed this cAMP-dependent activation, indicating an involvement of cAMP/PKA-mediated signalling pathway in ATPase, ANT and AK deficit. Consistently, DS-HSF showed decreased basal levels of cAMP and reduced PKA activity.Despite the impairment of mitochondrial energy apparatus, no changes in cellular energy status but increased basal levels of L-lactate were found in DS-HSF which partially offset for mitochondrial energy deficit by increasing glycolysis and mitochondrial mass.These results give new insight into the molecular basis for mitochondrial dysfunction in DS and might provide a molecular explanation for some clinical features of the syndrome.

Approximately 6% of newborns at term are small for gestational age (SGA) and present a birth weight and/or length less than -2SD from the mean. SGA infants are at increased risk for perinatal morbidity, associated psychological and/or mental problems, persistent short stature (about 15% of subjects) and metabolic alterations. Insulin-like growth factors (IGFs), their common receptor (IGF1R) and their binding proteins (IGFBPs) play a critical role in fetal and postnatal growth. In these genes common polymorphisms, such as single nucleotide polymorphisms and variable number of tandem repeats, have been investigated with conflicting results with respect to SGA-related outcomes, and the functional role of these gene variants remains to be elucidated.DESIGN:The study group consisted of 100 pre-pubertal short children born SGA and 94 healthy controls, matched for sex and age, recruited at the Department of Biomedicine of Development Age of the Bari University and at the Paediatric Department of the Messina Hospital. In the present study we analyzed the allelic frequency of the polymorphisms -795 G/A, -667 G/A, -396 C/T in the IGFBP3 in SGA children and their influence on the basal and insulin-stimulated transcriptional activity of the gene.RESULTS:We found that the polymorphisms -667 G/A and -396 C/T in the IGFBP3 promoter region are capable of having an effect on the transcriptional activity of the gene, although with opposing effects. Interestingly, the -667 G/A polymorphism has a negative impact on the IGFBP3 transcription, while the -396 C/T polymorphism determines an increase of the transcriptional activity of the IGFBP3 gene promoter. Interestingly, we found that the -396 C/T polymorphism correlates with lower birth length in SGA children. Most importantly, while the diminished IGFBP3 transcriptional activity induced by the -667A polymorphism was significantly recovered after insulin administration (p-value<0.05), the increased transcriptional activity caused by the -396T polymorphism was not restored to baseline levels by insulin.CONCLUSIONS:Altogether our results demonstrated that the -667 G/A and the -396 C/T polymorphisms in IGFBP3 promoter region influence the basal transcriptional activity of the gene.Copyright © 2011 Elsevier Ltd. All rights reserved.

Aerobic glycolysis, namely the Warburg effect, is the main hallmark of cancer cells. Mitochondrial respiratory dysfunction has been proposed to be one of the major causes for such glycolytic shift. This hypothesis has been revisited as tumors appear to undergo waves of gene regulation during progression, some of which rely on functional mitochondria. In this framework, the role of mitochondrial complex I is still debated, in particular with respect to the effect of mitochondrial DNA mutations in cancer metabolism. The aim of this work is to provide the proof of concept that functional complex I is necessary to sustain tumor progression.MethodsComplex I- osteosarcoma cells were complemented with allotopically expressed complex I subunit 1 (MT-ND1). Complex I re-assembly and function recovery, also in terms of NADH consumption, were assessed. Clones were tested for their ability to grow in soft agar and to generate tumor masses in nude mice. Hypoxia levels were evaluated via pimonidazole staining and hypoxia-inducible factor-1? (HIF-1?) immunoblotting and histochemical staining. 454-pyrosequencing was implemented to obtain global transcriptomic profiling of allotopic and non-allotopic xenografts.ResultsComplementation of a truncative mutation in the gene encoding MT-ND1, showed that a functional enzyme was required to perform the glycolytic shift during the hypoxia response and to induce a Warburg profile in vitro and in vivo, fostering cancer progression. Such trigger was mediated by HIF-1?, whose stabilization was regulated after recovery of the balance between ?-ketoglutarate and succinate due to a recuperation of NADH consumption that followed complex I rescue.ConclusionRespiratory complex I is essential for the induction of Warburg effect and adaptation to hypoxia of cancer cells, allowing them to sustain tumor growth. Differently from other mitochondrial tumor suppressor genes, therefore, a complex I severe mutation such as the one here reported may confer anti-tumorigenic properties, highlighting the prognostic values of such genetic markers in cancer.

Insulin-like growth factors (IGFs), their common receptors (IGFIRs) and their binding proteins (IGFPBs) play a critical role in fetal and postnatal growth. Only exceptionally mutations or deletions of IGF-related genes have been reported in short children. For this reason, the attention has been focused on the functional study of IGF-related promoter genes in search of new regulatory elements and factors that might alter gene expression. Among these genes, IGFBP3 plays a key role because it transports more than 75% of serum IGFs, extends the half-life of IGFs and modulates their biological effects. In addition, IGFBP3 also has IGF-independent effects, including cell growth inhibition and induction of apoptosis. The literature reports that the IGFBP3 gene is a direct target of p53 and contains two p53 Responsive Elements (REs) located in intron 1 and intron 2: box A and box B, respectively. Moreover, it has been reported that ?Np63? down-regulates IGFBP3 expression.

The regulation of insulin-like growth factor-binding protein 3 (IGFBP3) gene expression is complex, because it can be induced by agents that both stimulate and inhibit the proliferation. The principal aim of this study was to investigate whether p73, a member of the p53 gene family, has a role in the regulation of the IGFBP3 expression and whether this regulation occurs in a context of cell survival or death. We demonstrate that IGFBP3 is a direct TAp73? (the p73 isoform that contains the trans-activation domain) target gene and activates the expression of IGFBP3 in actively proliferating cells. As IGFBP3 plays a key role in regulating the growth hormone/insulin-like growth factor type 1 (GH/IGF1) axis, whose alterations in gene expression appear to have a role in the growth failure of children born small for gestational age (SGA), we measured the mRNA expression levels of p73 and IGFBP3 in a group of SGA children. We found that mRNA expression levels of p73 and IGFBP3 are significantly lower in SGA children compared with controls and, in particular, p73 mRNA expression is significantly lower in SGA children with respect to height. Our results shed light on the intricate GH/IGF pathway, suggesting p73 as a good biomarker of the clinical risk for SGA children to remain short in adulthood.

Eukaryotic cells contain a population of mitochondria, variable in number and shape, which in turn contain multiple copies of a tiny compact genome (mtDNA) whose expression and function is strictly coordinated with the nuclear one. mtDNA copy number varies between different cell or tissues types, both in response to overall metabolic and bioenergetics demands and as a consequence or cause of specific pathological conditions. Here we present a novel and reliable methodology to assess the effective mtDNA copy number per diploid genome by investigating off-target reads obtained by whole-exome sequencing (WES) experiments. We also investigate whether and how mtDNA copy number correlates with mitochondrial mass, respiratory activity and expression levels. Analyzing six different tissues from three age- and sex-matched human individuals, we found a highly significant linear correlation between mtDNA copy number estimated by qPCR and the frequency of mtDNA off target WES reads. Furthermore, mtDNA copy number showed highly significant correlation with mitochondrial gene expression levels as measured by RNA-Seq as well as with mitochondrial mass and respiratory activity. Our methodology makes thus feasible, at a large scale, the investigation of mtDNA copy number in diverse cell-types, tissues and pathological conditions or in response to specific treatments.

p53 is a central hub in controlling cell proliferation. To maintain genome integrity in response to cellular stress, p53 directly regulates the transcription of genes involved in cell cycle arrest, DNA repair, apoptosis and/or senescence. An array of post-translational modifications and protein-protein interactions modulates its stability and activities in order to avoid malignant transformation. However, to date it is still not clear how cells decide their own fate in response to different types of stress. We described here that the human TRIM8 protein, a member of the TRIM family, is a new modulator of the p53-mediated tumor suppression mechanism. We showed that under stress conditions, such as UV exposure, p53 induced the expression of TRIM8, which in turn stabilized p53 leading to cell cycle arrest and reduction of cell proliferation through enhancement of CDKN1A (p21) and GADD45 expression. TRIM8 silencing reduced the capacity of p53 to activate genes involved in cell cycle arrest and DNA repair, in response to cellular stress. Concurrently, TRIM8 overexpression induced the degradation of the MDM2 protein, the principal regulator of p53 stability. Co-immunoprecipitation experiments showed that TRIM8 physically interacted with p53, impairing its interaction with MDM2. Altogether, our results reveal a previously unknown regulatory pathway controlling p53 activity and suggest TRIM8 as a novel therapeutic target to enhance p53 tumor suppressor activity.

In some tumours, despite a wild-type p53 gene, the p53 pathway is inactivated by alterations in its regulators or by unknown mechanisms, leading to resistance to cytotoxic therapies. Understanding the mechanisms of functional inactivation of wild-type p53 in these tumours may help to define prospective targets for treating cancer by restoring p53 activity. Recently, we identified TRIM8 as a new p53 modulator, which stabilizes p53 impairing its association with MDM2 and inducing the reduction of cell proliferation. In this paper we demonstrated that TRIM8 deficit dramatically impairs p53-mediated cellular responses to chemotherapeutic drugs and that TRIM8 is down regulated in patients affected by clear cell Renal Cell Carcinoma (ccRCC), an aggressive drug-resistant cancer showing wild-type p53. These results suggest that down regulation of TRIM8 might be an alternative way to suppress p53 activity in RCC. Interestingly, we show that TRIM8 expression recovery in RCC cell lines renders these cells sensitive to chemotherapeutic treatments following p53 pathway re-activation. These findings provide the first mechanistic link between TRIM8 and the drug resistance of ccRCC and suggest more generally that TRIM8 could be used as enhancer of the chemotherapy efficacy in cancers where p53 is wild-type and its pathway is defective.

TRIM8 plays a key role in controlling the p53 molecular switch that sustains the transcriptional activation of cell cycle arrest genes and response to chemotherapeutic drugs. The mechanisms that regulate TRIM8, especially in cancers like clear cell Renal Cell Carcinoma (ccRCC) and colorectal cancer (CRC) where it is low expressed, are still unknown. However, recent studies suggest the potential involvement of some microRNAs belonging to miR-17-92 and its paralogous clusters, which could include TRIM8 in a more complex pathway.MethodsWe used RCC and CRC cell models for in-vitro experiments, and ccRCC patients and xenograft transplanted mice for in vivo assessments. To measure microRNAs levels we performed RT-qPCR, while steady-states of TRIM8, p53, p21 and N-MYC were quantified at protein level by Western Blotting as well as at transcript level by RT-qPCR. Luciferase reporter assays were performed to assess the interaction between TRIM8 and specific miRNAs, and the potential effects of this interaction on TRIM8 expression. Moreover, we treated our cell models with conventional chemotherapeutic drugs or tyrosine kinase inhibitors, and measured their response in terms of cell proliferation by MTT and colony suppression assays.ResultsWe showed that TRIM8 is a target of miR-17-5p and miR-106b-5p, whose expression is promoted by N-MYC, and that alterations of their levels affect cell proliferation, acting on the TRIM8 transcripts stability, as confirmed in ccRCC patients and cell lines. In addition, reducing the levels of miR-17-5p/miR-106b-5p, we increased the chemo-sensitivity of RCC/CRC-derived cells to anti-tumour drugs used in the clinic. Intriguingly, this occurs, on one hand, by recovering the p53 tumour suppressor activity in a TRIM8-dependent fashion and, on the other hand, by promoting the transcription of miR-34a that turns off the oncogenic action of N-MYC. This ultimately leads to cell proliferation reduction or block, observed also in colon cancer xenografts overexpressing TRIM8.ConclusionsIn this paper we provided evidence that TRIM8 and its regulators miR-17-5p and miR-106b-5 participate to a feedback loop controlling cell proliferation through the reciprocal modulation of p53, miR-34a and N-MYC. Our experiments pointed out that this axis is pivotal in defining drug responsiveness of cancers such ccRCC and CRC.

The TRIM8/GERP protein is a member of the TRIM family defined by the presence of a common domain structure composed of a tripartite motif including a RING-finger, one or two B-box domains, and a coiled-coil motif. The TRIM8 gene maps on chromosome 10 within a region frequently found deleted and rearranged in tumours and transcribes a 3.0-kB mRNA. Its expression is mostly ubiquitously in murine and human tissues, and in epithelial and lymphoid cells, it can be induced by IFNgamma. The protein spans 551 aa and is highly conserved during evolution. TRIM8 plays divergent roles in many biological processes, including important functions in inflammation and cancer through regulating various signalling pathways. In regulating cell growth, TRIM8 exerts either a tumour suppressor action, playing a prominent role in regulating p53 tumour suppressor activity, or an oncogene function, through the positive regulation of the NF-kappaB pathway. The molecular mechanisms underlying this dual role in human cancer will be discussed in depth in this review, and it will highlight the challenge and importance of developing novel therapeutic strategies specifically aimed at blocking the pro-oncogenic arm of the TRIM8 signalling pathway without affecting its tumour suppressive effects.