ABSTRACT: Due to genome instability, most cancers exhibit loss of regions containing tumor suppressor genes and collateral loss of other genes. To identify cancer-specific vulnerabilities that are the result of copy number losses, we performed integrated analyses of genome-wide copy number and RNAi profiles and identified 56 genes for which gene suppression specifically inhibited the proliferation of cells harboring partial copy number loss of that gene. These CYCLOPS (copy number alterations yielding cancer liabilities owing to partial loss) genes are enriched for spliceosome, proteasome, and ribosome components. One CYCLOPS gene, PSMC2, encodes an essential member of the 19S proteasome. Normal cells express excess PSMC2, which resides in a complex with PSMC1, PSMD2, and PSMD5 and acts as a reservoir protecting cells from PSMC2 suppression. Cells harboring partial PSMC2 copy number loss lack this complex and die after PSMC2 suppression. These observations define a distinct class of cancer-specific liabilities resulting from genome instability.
Project description:Genomic instability is a hallmark of human cancer, and results in widespread somatic copy number alterations. We used a genome-scale shRNA viability screen in human cancer cell lines to systematically identify genes that are essential in the context of particular copy-number alterations (copy-number associated gene dependencies). The most enriched class of copy-number associated gene dependencies was CYCLOPS (Copy-number alterations Yielding Cancer Liabilities Owing to Partial losS) genes, and spliceosome components were the most prevalent. One of these, the pre-mRNA splicing factor SF3B1, is also frequently mutated in cancer. We validated SF3B1 as a CYCLOPS gene and found that human cancer cells harboring partial SF3B1 copy-loss lack a reservoir of SF3b complex that protects cells with normal SF3B1 copy number from cell death upon partial SF3B1 suppression. These data provide a catalog of copy-number associated gene dependencies and identify partial copy-loss of wild-type SF3B1 as a novel, non-driver cancer gene dependency.
Project description:Copy-number alterations Yielding Cancer Liabilities Owing to Partial losS (CYCLOPS) genes have been recently identified as the most enriched class of copy-number associated gene dependencies in human cancer. These genes are cell essential and render tumor cells highly sensitive to the expression of the remaining copy. Chromophobe renal cell carcinoma (chRCC) is characterized by frequent chromosomal deletions, but the relevance of CYCLOPS genes in this tumor subtype is unclear. We found 39 (31%) of 124 recently published candidate CYCLOPS genes (B. Paolella et al., eLife 2017;6:e23268) located on 7 autosomes that are frequently lost in chRCC. GISTIC and RNA-seq data obtained from the TCGA-KICH database showed that 62% of these CYCLOPS genes had significantly lower expression levels in samples with deletion of the respective gene. As copy number (CN) loss of the CYCLOPS gene SF3B1 (Splicing factor 3B subunit 1) has been recently reported in 71% chRCC, we explored the relevance of SF3B1 CN alteration and SF3B1 expression in a set of chRCC and additional oncocytic renal neoplasms. The frequency of SF3B1 CN loss (65%) was similar to that obtained from the TCGA-KICH database and correlated significantly with both lower SF3B1 mRNA (P < .05) and protein expression (P < .001). Other tumor subtypes with oncocytic cytoplasm had normal SF3B1 CN and displayed strong SF3B1 protein expression. These results suggest that CN loss of CYCLOPS genes is a characteristic feature in chRCC. Since many CYCLOPS genes code for components of proteasomes and transcriptional regulation, their alteration could make chRCC vulnerable to targeted drugs.
Project description:BACKGROUND:Gastric cancer, a leading cause of cancer death worldwide, has been little studied compared with other cancers that impose similar health burdens. Our goal is to assess genomic copy-number loss and the possible functional consequences and therapeutic implications thereof across a large series of gastric adenocarcinomas. METHODS:We used high-density single-nucleotide polymorphism microarrays to determine patterns of copy-number loss and allelic imbalance in 74 gastric adenocarcinomas. We investigated whether suppressor of tumorigenesis and/or proliferation (STOP) genes are associated with genomic copy-number loss. We also analyzed the extent to which copy-number loss affects Copy-number alterations Yielding Cancer Liabilities Owing to Partial losS (CYCLOPS) genes-genes that may be attractive targets for therapeutic inhibition when partially deleted. RESULTS:The proportion of the genome subject to copy-number loss varies considerably from tumor to tumor, with a median of 5.5 %, and a mean of 12 % (range 0-58.5 %). On average, 91 STOP genes were subject to copy-number loss per tumor (median 35, range 0-452), and STOP genes tended to have lower copy-number compared with the rest of the genes. Furthermore, on average, 1.6 CYCLOPS genes per tumor were both subject to copy-number loss and downregulated, and 51.4 % of the tumors had at least one such gene. CONCLUSIONS:The enrichment of STOP genes in regions of copy-number loss indicates that their deletion may contribute to gastric carcinogenesis. Furthermore, the presence of several deleted and downregulated CYCLOPS genes in some tumors suggests potential therapeutic targets in these tumors.
Project description:BACKGROUND:Hepatocellular carcinoma (HCC) is one of the most lethal and malignant tumours worldwide. New therapeutic targets for HCC are urgently needed. CYCLOPS (copy number alterations yielding cancer liabilities owing to partial loss) genes have been noted to be associated with cancer-targeted therapies. Therefore, we intended to explore the effects of the CYCLOPS gene RBM17 on HCC oncogenesis to determine if it could be further used for targeted therapy. METHODS:We collected data on 12 types of cancer from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) queries for comparison with adjacent non-tumour tissues. RBM17 expression levels, clinicopathological factors and survival times were analysed. RNAseq data were downloaded from the Encyclopaedia of DNA Elements database for molecular mechanism exploration. Two representative HCC cell models were built to observe the proliferation capacity of HCC cells when RBM17 expression was inhibited by shRBM17. Cell cycle progression and apoptosis were also examined to investigate the pathogenesis of RBM17. RESULTS:Based on 6,136 clinical samples, RBM17 was markedly overexpressed in most cancers, especially HCC. Moreover, data from 442 patients revealed that high RBM17 expression levels were related to a worse prognosis. Overexpression of RBM17 was related to the iCluster1 molecular subgroup, TNM stage, and histologic grade. Pathway analysis of RNAseq data suggested that RBM17 was involved in mitosis. Further investigation revealed that the proliferation rates of HepG2 (P = 0.003) and SMMC-7721 (P = 0.030) cells were significantly reduced when RBM17 was knocked down. In addition, RBM17 knockdown also arrested the progression of the cell cycle, causing cells to halt at the G2/M phase. Increased apoptosis rates were also found in vitro. CONCLUSION:These results suggest that RBM17 is a potential therapeutic target for HCC treatment.
Project description:The TRIM5 proteins are cellular restriction factors that prevent retroviral infection in a species-specific manner. Multiple experiments indicate that restriction activity requires accessory host factors, including E2-enzymes. To better understand the mechanism of restriction, we conducted yeast-two hybrid screens to identify proteins that bind to two TRIM5 orthologues.The only cDNAs that scored on repeat testing with both TRIM5 orthologues were the proteasome subunit PSMC2 and ubiquitin. Using co-immunoprecipitation assays, we demonstrated an interaction between TRIM5? and PSMC2, as well as numerous other proteasome subunits. Fluorescence microscopy revealed co-localization of proteasomes and TRIM5? cytoplasmic bodies. Forster resonance energy transfer (FRET) analysis indicated that the interaction between TRIM5 and PSMC2 was direct. Previous imaging experiments demonstrated that, when cells are challenged with fluorescently-labeled HIV-1 virions, restrictive TRIM5? orthologues assemble cytoplasmic bodies around incoming virion particles. Following virus challenge, we observed localization of proteasome subunits to rhTRIM5? cytoplasmic bodies that contained fluorescently labeled HIV-1 virions.Taken together, the results presented here suggest that localization of the proteasome to TRIM5? cytoplasmic bodies makes an important contribution to TRIM5?-mediated restriction.
Project description:BACKGROUND:Obesity and nonalcoholic steatohepatitis (NASH) are well-known risk factors of hepatocellular carcinoma (HCC). The lipid-rich environment enhances the proliferation and metastasis abilities of tumor cells. Previous studies showed the effect of the ubiquitin-proteasome system (UPS) on tumor cell proliferation. However, the underlying mechanism of UPS in regulating the proliferation of lipid-rich tumor cells is not totally clear. RESULTS:Here, we identify two proteasome 26S subunits, non-ATPase 1 and 2 (PSMD1 and PSMD2), which regulate HepG2 cells proliferation via modulating cellular lipid metabolism. Briefly, the knockdown of PSMD1 and/or PSMD2 decreases the formation of cellular lipid droplets, the provider of the energy and membrane components for tumor cell proliferation. Mechanically, PSMD1 and PSMD2 regulate the expression of genes related to de novo lipid synthesis via p38-JNK and AKT signaling. Moreover, the high expression of PSMD1 and PSMD2 is significantly correlated with poor prognosis of HCC. CONCLUSION:We demonstrate that PSMD1 and PSMD2 promote the proliferation of HepG2 cells via facilitating cellular lipid droplet accumulation. This study provides a potential therapeutic strategy for the treatment of lipid-rich tumors.
Project description:Breast cancer cell lines containing stable dox inducible shRNAs targeting SF3B1 were profiled by RNA sequencing. We determined the effect of gene expression and splicing changes before and after knocking down SF3B1 in cell lines with normal copy number (SF3B1neutral) or partial copy loss (SF3B1loss) cell lines Overall design: RNA profiles for SF3B1 suppression were generated from 8 breast cancer cell line pairs (-/+ dox) with no techincal replicates.
Project description:BACKGROUND:Fruits are unique to flowering plants and play a central role in seed maturation and dispersal. Molecular dissection of fruit ripening has received considerable interest because of the biological and dietary significance of fruit. To better understand the regulatory mechanisms underlying fruit ripening, we report here the first comprehensive analysis of the nuclear proteome in tomato fruits. RESULTS:Nuclear proteins were isolated from tomatoes in different stages of ripening, and subjected to iTRAQ (isobaric tags for relative and absolute quantification) analysis. We show that the proteins whose abundances change during ripening stages are involved in various cellular processes. We additionally evaluate changes in the nuclear proteome in the ripening-deficient mutant, ripening-inhibitor (rin), carrying a mutation in the transcription factor RIN. A set of proteins were identified and particular attention was paid to SlUBC32 and PSMD2, the components of ubiquitin-proteasome pathway. Through chromatin immunoprecipitation and gel mobility shift assays, we provide evidence that RIN directly binds to the promoters of SlUBC32 and PSMD2. Moreover, loss of RIN function affects protein ubiquitination in nuclei. SlUBC32 encodes an E2 ubiquitin-conjugating enzyme and a genome-wide survey of the E2 gene family in tomatoes identified five more E2s as direct targets of RIN. Virus-induced gene silencing assays show that two E2s are involved in the regulation of fruit ripening. CONCLUSIONS:Our results uncover a novel function of protein ubiquitination, identifying specific E2s as regulators of fruit ripening. These findings contribute to the unraveling of the gene regulatory networks that control fruit ripening.
Project description:BACKGROUND: In traditional Chinese medicine (TCM) clinical practice, ZHENG (also known as TCM syndrome) helps to understand the human homeostasis and guide individualized treatment. However, the scientific basis of ZHENG remains unclear due to limitations of current reductionist approaches. METHODS: We collected the leukocyte samples of three hepatitis B-caused cirrhosis (HBC) patients with dampness-heat accumulation syndrome (DHAS) and three HBC patients with liver depression and spleen deficiency syndrome (LDSDS) for microarray analysis. We generated Gene-Regulatory-Networks (GeneRelNet) from the differentially expressed genes (DEGs) of microarray date. Core genes were validated using anther independent cohort of 40 HBC patients (20 DHAS, 20 LDSDS) with RT-PCR. RESULTS: There were 2457 mapped genes were differentially expressed between DHAS and LDSDS (Fold change ? 2.0, P < 0.05). There were markedly different genes co-expression patterns in DHAS and LDSDS. Furthermore, three differential co-expression genes including purine nucleoside phosphorylase (PNP); aquaporin 7 (AQP7) and proteasome 26S subunit, non-ATPase 2 (PSMD2) were screened by GeneRelNets, and their mRNA expressions were further validated by real time RT-PCR. The results were consistent with microarray. The PNP (P = 0.007), AQP7 (P = 0.038) and PSMD2 (P = 0.009) mRNA expression is significant difference between DHAS and LDSDS using the non-parametric test. Furthermore, we constructed an mRNA panel of PNP, AQP7 and PSMD2 (PAP panel) by logistic regression model, and evaluated the PAP panel to distinguish DHAS from LDSDS by area under the receiver operating characteristic curve (AUC) analysis, which showed a higher accuracy (AUC = 0.835). Gene ontology (GO) analysis indicated that the DHAS is most likely related to system process while the functions overrepresented by LDSDS most related to the response to stimulus. CONCLUSIONS: This study suggested that there are particular transcriptional profiles, genes co-expressions patterns and functional properties of DHAS and LDSDS, and PNP, AQP7, and PSMD2 may be involved in ZHENG differentiation of DHAS and LDSDS in HBC.
Project description:<h4>Background</h4>Cyclops syndrome is characterized by loss of terminal knee extension due to proliferative fibrous nodule formation in the intercondylar notch. This complication occurs in the early postoperative period after anterior cruciate ligament reconstruction (ACLR). The pathogenesis of Cyclops syndrome is not well understood.<h4>Hypothesis</h4>Persistent hamstring contracture after ACLR is associated with an increased risk of subsequent Cyclops syndrome.<h4>Study design</h4>Case-control study; Level of evidence, 3.<h4>Methods</h4>The files of 45 patients who underwent arthroscopic debridement of a Cyclops lesion after ACLR were analyzed. Recorded data included demographic information and technical details of surgery. Preoperative magnetic resonance images were also analyzed, and patients with femoral bone bruising were identified. Passive and active range of motion were recorded in all patients preoperatively and at 3 and 6 weeks after surgery to address the Cyclops lesion. Passive extension deficit was evaluated in comparison with the contralateral limb and classified as secondary to hamstring contracture when contracture was observed and palpated in the prone position and when the extension deficit was reversed after exercises performed to fatigue the hamstrings. A control group was selected using a random numbers table among our entire ACLR cohort. Statistical analysis was performed to analyze differences between the 2 groups.<h4>Results</h4>There was no significant difference between the groups with regard to age at ACLR, sex distribution, time from injury to surgery (<i>P</i> > .05), proportion of professional athletes, presence of femoral bone bruise, or technical aspects of surgery. The overall extension deficit incidence was significantly higher in the Cyclops group at 3 weeks (Cyclops, 71%; control, 22%) (<i>P</i> < .001) and at 6 weeks (Cyclops, 60%; control, 7%) (<i>P</i> < .001). The extension deficit related to hamstring contracture was significantly higher in the Cyclops group at 3 weeks (Cyclops, 58%; control, 22%) (<i>P</i> < .001) and at 6 weeks (Cyclops, 29%; control, 2%) (<i>P</i> < .001).<h4>Conclusion</h4>The Cyclops lesion is associated with a persistent hamstring contracture at 3 and 6 weeks after ACLR.