Comparative proteomic analysis of osteosarcoma cell and human primary cultured osteoblastic cell

Genetic deviation associated with photodynamic therapy in HeLa cell

Photodynamic therapy (PDT) is a method that is used in cancer treatment. The main therapeutic effect is the production of singlet oxygen (1O2). Phthalocyanines for PDT produce high singlet oxygen with absorbers of about 600-700 nm.

AIM

It is aimed to analyze cancer cell pathways by flow cytometry analysis and cancer-related genes with q-PCR device by applying phthalocyanine L1ZnPC, which we use as photosensitizer in photodynamic therapy, in HELA cell line. In this study, we investigate the molecular basis of L1ZnPC's anti-cancer activity.

MATERIAL METHOD

The cytotoxic effects of L1ZnPC, a phthalocyanine obtained from our previous study, in HELA cells were evaluated and it was determined that it led to a high rate of death as a result. The result of photodynamic therapy was analyzed using q-PCR. From the data received at the conclusion of this investigation, gene expression values were calculated, and expression levels were assessed using the 2-∆∆Ct method to examine the relative changes in these values. Cell death pathways were interpreted with the FLOW cytometer device. One-Way Analysis of Variance (ANOVA) and the Tukey-Kramer Multiple Comparison Test with Post-hoc Test were used for the statistical analysis.

CONCLUSION

In our study, it was observed that HELA cancer cells underwent apoptosis at a rate of 80% with drug application plus photodynamic therapy by flow cytometry method. According to q-PCR results, CT values ​​of eight out of eighty-four genes were found to be significant and their association with cancer was evaluated. L1ZnPC is a new phthalocyanine used in this study and our findings should be supported by further studies. For this reason, different analyses are needed to be performed with this drug in different cancer cell lines. In conclusion, according to our results, this drug looks promising but still needs to be analyzed through new studies. It is necessary to examine in detail which signaling pathways they use and their mechanism of action. For this, additional experiments are required.

Inflammation produced by senescent osteocytes mediates age-related bone loss

Purpose

The molecular mechanisms of age-related bone loss are unclear and without valid drugs yet. The aims of this study were to explore the molecular changes that occur in bone tissue during age-related bone loss, to further clarify the changes in function, and to predict potential therapeutic drugs.

Methods

We collected bone tissues from children, middle-aged individuals, and elderly people for protein sequencing and compared the three groups of proteins pairwise, and the differentially expressed proteins (DEPs) in each group were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). K-means cluster analysis was then used to screen out proteins that continuously increased/decreased with age. Canonical signaling pathways that were activated or inhibited in bone tissue along with increasing age were identified by Ingenuity Pathway Analysis (IPA). Prediction of potential drugs was performed using the Connectivity Map (CMap). Finally, DEPs from sequencing were verified by Western blot, and the drug treatment effect was verified by quantitative real-time PCR.

Results

The GO and KEGG analyses show that the DEPs were associated with inflammation and bone formation with aging, and the IPA analysis shows that pathways such as IL-8 signaling and acute-phase response signaling were activated, while glycolysis I and EIF2 signaling were inhibited. A total of nine potential drugs were predicted, with rapamycin ranking the highest. In cellular experiments, rapamycin reduced the senescence phenotype produced by the H₂O₂-stimulated osteocyte-like cell MLO-Y4.

Conclusion

With age, inflammatory pathways are activated in bone tissue, and signals that promote bone formation are inhibited. This study contributes to the understanding of the molecular changes that occur in bone tissue during age-related bone loss and provides evidence that rapamycin is a drug of potential clinical value for this disease. The therapeutic effects of the drug are to be further studied in animals.

Ubiquitin C-terminal hydrolase-L1 expression in non-small-cell lung cancer and its association with clinicopathological features and prognosis

UbiquitinC-terminal hydrolase-L1 (UCH-L1) is a cysteine hydrolase. It functions as a ubiquitin hydrolase, stabilizes the ubiquitin monomer, and affects cell division through cell cycle protein deubiquitination. Abnormal UCH-L1 expression is closely related to the occurrence and development of several tumors. Although some in vitro studies have demonstrated the significance of UCH-L1 in non-small-cell lung cancer (NSCLC), only few clinical studies have focused on the UCH-L1 expression in NSCLC, and the results are controversial and non-uniform. We investigated the UCH-L1 expression in 401 cases of surgically resected NSCLC, including 286 cases of adenocarcinoma (ADC) and 65 cases of squamous cell carcinoma. The associations between the UCH-L1 expression and clinicopathological features, programmed cell death-ligand 1 (PD-L1) expression, and prognostic significance were analyzed. For NSCLC, the UCH-L1 expression is associated with sex, smoking history, tumor size (>3 cm), lymphocyte infiltration, advanced pathological stages, and shortened overall survival (OS; 89.72 vs. 114.55 months; P = 0.005), but not PD-L1 expression. The UCH-L1 expression in ADC is associated with advanced pathological stages, pleural invasion, and shortened OS (90.38 vs. 118.55 months; P = 0.010). Multivariate analysis confirmed that UCH-L1 expression was an independent poor prognostic factor for NSCLC (OS: hazard ratio [HR], 1.854; 95% confidence interval [CI], 1.132-3.038; P = 0.014). Our results suggest that the UCH-L1 expression differs across tumors with different clinicopathological features, and it is related to poor prognosis.

Molecular Chaperones in Osteosarcoma: Diagnosis and Therapeutic Issues

Osteosarcoma (OS) is the most common form of primary bone tumor affecting mainly children and young adults. Despite therapeutic progress, the 5-year survival rate is 70%, but it drops drastically to 30% for poor responders to therapies or for patients with metastases. Identifying new therapeutic targets is thus essential. Heat Shock Proteins (HSPs) are the main effectors of Heat Shock Response (HSR), the expression of which is induced by stressors. HSPs are a large family of proteins involved in the folding and maturation of other proteins in order to maintain proteostasis. HSP overexpression is observed in many cancers, including breast, prostate, colorectal, lung, and ovarian, as well as OS. In this article we reviewed the significant role played by HSPs in molecular mechanisms leading to OS development and progression. HSPs are directly involved in OS cell proliferation, apoptosis inhibition, migration, and drug resistance. We focused on HSP27, HSP60, HSP70 and HSP90 and summarized their potential clinical uses in OS as either biomarkers for diagnosis or therapeutic targets. Finally, based on different types of cancer, we consider the advantage of targeting heat shock factor 1 (HSF1), the major transcriptional regulator of HSPs in OS.

Dysregulation of the Ubiquitin Proteasome System in Human Malignancies: A Window for Therapeutic Intervention

Simple Summary

The ubiquitin proteasome system (UPS) governs the non-lysosomal degradation of oxidized, damaged, or misfolded proteins in eukaryotic cells. Dysregulation of the UPS results in loss of ability to maintain protein quality through proteolysis, and is closely related to the development of various malignancies and tumorigenesis. Here, we provide a comprehensive general overview on the regulation and roles of UPS and discuss the mechanisms linking dysregulated UPS to human malignancies. Inhibitors developed against components of the UPS, which include U.S. Food and Drug Administration FDA-approved and those currently undergoing clinical trials, are also presented in this review.

Abstract

The ubiquitin proteasome system (UPS) governs the non-lysosomal degradation of oxidized, damaged, or misfolded proteins in eukaryotic cells. This process is tightly regulated through the activation and transfer of polyubiquitin chains to target proteins which are then recognized and degraded by the 26S proteasome complex. The role of UPS is crucial in regulating protein levels through degradation to maintain fundamental cellular processes such as growth, division, signal transduction, and stress response. Dysregulation of the UPS, resulting in loss of ability to maintain protein quality through proteolysis, is closely related to the development of various malignancies and tumorigenesis. Here, we provide a comprehensive general overview on the regulation and roles of UPS and discuss functional links of dysregulated UPS in human malignancies. Inhibitors developed against components of the UPS, which include U.S. Food and Drug Administration FDA-approved and those currently undergoing clinical trials, are also presented in this review.

Mitochondrial Protein UQCRC1 is Oncogenic and a Potential Therapeutic Target for Pancreatic Cancer

Purpose: Pancreatic ductal adenocarcinoma (PDAC) is a malignant disease with a poor prognosis. One prominent aspect of PDAC that contributes to its aggressive behavior is its altered cellular metabolism. The aim of this study was to characterize the oncogenic effects of ubiquinol-cytochrome c reductase core protein I (UQCRC1), a key component of mitochondrial complex III, in PDAC development and to assess its potential as a therapeutic target for PDAC.

Experimental Design: The expression of UQCRC1 in human PDAC tissues and p48-Cre/p53Flox/WT/LSL-KrasG12D (KPC) mouse pancreatic intraepithelial neoplasias (PanINs) was determined by immunohistochemistry. The role of UQCRC1 in promoting PDAC growth was evaluated in vitro in PANC-1 and CFPAC-1 cells and in vivo in transplanted mouse models of PDAC. Extracellular flux and RNA-Seq analyses were applied to investigate the mechanism of UQCRC1 in the regulation of mitochondrial metabolism and PDAC cell growth. The therapeutic potential of UQCRC1 in PDAC was assessed by knockdown of UQCRC1 using an RNA interference approach.

Results: UQCRC1 expression showed a gradual increase during the progression from PanIN stages to PDAC in KPC mice. Elevated expression of UQCRC1 was observed in 72.3% of PDAC cases and was correlated with poor prognosis of the disease. UQCRC1 promoted PDAC cell growth in both in vitro experiments and in vivo subcutaneous and orthotopic mouse models. UQCRC1 overexpression resulted in increased mitochondrial oxidative phosphorylation (OXPHOS) and ATP production. The overproduced ATP was released into the extracellular space via the pannexin 1 channel and then functioned as an autocrine or paracrine agent to promote cell proliferation through the ATP/P2Y2-RTK/AKT axis. UQCRC1 knockdown or ATP release blockage could effectively inhibit PDAC growth.

Conclusion: UQCRC1 has a protumor function and may serve as a potential prognostic marker and therapeutic target for PDAC.

In Vitro Generation of Anti-Osteosarcoma Cytotoxic Activity Using Dendritic Cells Loaded with Heat Shock Protein 70-Peptide Complexes

Introduction: This study aimed at evaluating the anti-osteosarcoma activity of cytotoxic T lymphocytes (CTLs) induced by dendritic cells (DCs) pulsed with heat shock protein 70-peptide complexes (Hsp70-PCs). Materials and methods: Human recombinant Hsp70 expression was analyzed using thin layer scanning and Western blot assay. Tumor antigens from Saos-2 cells were extracted to reconstitute Hsp70-PCs. Maturation of cord blood-derived DC was evaluated by alkaline phosphatase-anti-alkaline phosphatase kit and inverted microscope. The anti-osteosarcoma activity of CTLs evoked by DCs loaded with Hsp70-PCs was determined using Thiazolyl Blue Tetrazolium Bromide (MTT) assay. Results: Hsp70 protein level in BL21 (DE3) increased in a time-dependent manner after induction. The expression of surface markers was upregulated and a typical dendritic morphology was observed in mature DCs. Allogeneic CTLs exhibited strong cytotoxic activity against Saos-2 cells. Conclusion: Our in vitro experiment demonstrated the potent induction of cytotoxic activity against osteosarcoma using DC-based vaccine loaded with Hsp70-PCs.

RNA Sequencing of Osteosarcoma Gene Expression Profile Revealed that miR-214-3p Facilitates Osteosarcoma Cell Proliferation via Targeting Ubiquinol-Cytochrome c Reductase Core Protein 1 (UQCRC1)

Background

Osteosarcoma (OS) is a common primary malignant bone tumor for which the molecular mechanisms remain unclear. Studies on coding and non-coding RNAs are needed to determine the molecular mechanism.

Material/Methods

To explore the potential roles of miRNAs and mRNA in OS, we determined the miRNA and mRNA expression profile of 3 pairs of OS and paracancerous tissues from patients with OS by sequencing and bioinformatics analysis. The expression levels of critical miRNAs and mRNAs were verified in 10 pairs of OS and paracancerous tissues. An miRNA inhibitor and mimics were used to investigate the interactions between miRNAs and target genes. The cell counting kit-8 assay was performed to evaluate OS cell proliferation after miRNA interference.

Results

A total of 184 miRNAs and 2501 mRNAs were identified (fold-change >2.0 or <2.0, P<0.05), with up-regulation of 82 miRNAs and 1320 mRNAs and down-regulation of 102 miRNAs and 1181 mRNAs in OS tissue. The protein protein interaction network revealed that UQCRC1 (ubiquinol-cytochrome c reductase core protein 1) is a critical gene and a potential target gene of miR-214-3p. Both UQCRC1 and miR-214-3p were significantly differentially expressed in OS tissue and cell lines (down and up-regulated, respectively). Down-regulated miR-214-3p expression increased UQCRC1 expression and suppressed OS cell proliferation. In contrast, overexpression of miR-214-3p decreased UQCRC1 expression and promoted OS cell proliferation.

Conclusions

High miR-214-3p expression may promote OS cell proliferation by targeting UQCRC1, providing insight into a potential therapeutic target for preventing and treating OS.

UQCRC1 downregulation is correlated with lymph node metastasis and poor prognosis in CRC

BACKGROUND

Mitochondrial dysfunction is common in cancer. UQCRC1 is a nuclear-encoded protein localized to the inner mitochondrial membrane; however, little is known about it in colorectal cancer (CRC). The purpose of this study was to investigate the expression pattern and the possible clinical significance of UQCRC1 in CRC.

METHODS

A total of 197 patients with CRC were enrolled in this study. Immunohistochemistry was used to evaluate the expression pattern of UQCRC1. The relationship between UQCRC1 and clinical characteristics, especially lymph node metastasis, was also assessed. In addition, we evaluated the significance of UQCRC1 in the prognosis for CRC patients.

RESULTS

UQCRC1 was downregulated in 28.9% (57/197) of human CRCs. Downregulation of UQCRC1 was correlated with increased lymph node metastasis (p < 0.001) and decreased disease-free survival (DFS) and overall survival (OS). Multivariate analysis revealed that downregulation of UQCRC1 was an independent prognostic factor both for DFS (HR 3.009; 95% CI: 1.613-8.548, P = 0.009) and OS (HR 4.062; 95% CI: 2.835-8.910, P = 0.001). In addition, downregulation of UQCRC1 was correlated with increased VEGF-C expression (P = 0.002).

CONCLUSION

UQCRC1 was downregulated in human CRC. Downregulation of UQCRC1 was correlated with increased lymph node metastasis and finally associated with decreased survival in CRC.

Ubiquitin carboxyl-terminal hydrolases: involvement in cancer progression and clinical implications

Protein ubiquitination and deubiquitination participate in a number of biological processes, including cell growth, differentiation, transcriptional regulation, and oncogenesis. Ubiquitin C-terminal hydrolases (UCHs), a subfamily of deubiquitinating enzymes (DUBs), includes four members: UCH-L1/PGP9.5 (protein gene product 9.5), UCH-L3, UCHL5/UCH37, and BRCA1-associated protein-1 (BAP1). Recently, more attention has been paid to the relationship between the UCH family and malignancies, which play different roles in the progression of different tumors. It remains controversial whether UCHL1 is a tumor promoter or suppressor. UCHL3 and UCH37 are considered to be tumor promoters, while BAP1 is considered to be a tumor suppressor. Studies have showed that UCH enzymes influence several signaling pathways that play crucial roles in oncogenesis, tumor invasion, and migration. In addition, UCH families are associated with tumor cell sensitivity to therapeutic modalities. Here, we reviewed the roles of UCH enzymes in the development of tumors, highlighting the potential consideration of UCH enzymes as new interesting targets for the development of anticancer drugs.

Focal adhesion kinase promotes progression and predicts poor clinical outcomes in patients with osteosarcoma

Osteosarcoma (OS) is a fatal form of musculoskeletal tumor that commonly leads to pulmonary metastatic disease. Traditional therapies such as surgery and chemotherapy are not effective treatment modalities in certain patients with OS; therefore, identifying the molecular mechanism of OS is imperative for the development of novel therapeutics. Previous studies have reported that focal adhesion kinase (FAK) is associated with numerous types of human malignancies. Therefore, in order to investigate the biological function of FAK in OS, the present study examined the expression levels of FAK in OS cell lines, OS tissues and paired normal tissue specimens by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). FAK expression in vitro was blocked using small interfering RNA (siRNA) to observe the invasion, proliferation and apoptosis trends of OS cells. Phosphoinositide-dependent kinase-1 (PDK1), AKT and BRAF protein levels were also evaluated by western blotting to analyze the effects of FAK depletion on the AKT and mitogen-activated protein kinase (MAPK) signaling pathways. A significantly reduced level of FAK mRNA was identified in paired normal tissues compared with OS tissues and cell lines. The invasive capability and proliferative potential of OS cells were suppressed due to the transient in vitro transfection of FAK siRNA. It was also demonstrated that decreased FAK expression facilitated the apoptosis of OS cells, as demonstrated by flow cytometric and western blotting analyses. Decreased FAK expression resulted in the downregulation of phosphorylated (p)-AKT, p-PDK1 and p-BRAF protein levels. Higher FAK expression levels are positively associated with clinicopathological characteristics of advanced Enneking stages (P<0.001) and recurrence (P=0.041) in patients with OS. Collectively, these data demonstrated that FAK is an important diagnostic biomarker for OS, and FAK siRNA therapy may be a potentially promising approach for the treatment of OS.

Systematic expression analysis of the mitochondrial complex III subunits identifies UQCRC1 as biomarker in clear cell renal cell carcinoma

Mitochondrial dysfunction is common in cancer, and the mitochondrial electron transport chain is often affected in carcinogenesis. So far, few is known about the expression of the mitochondrial complex III (ubiquinol-cytochrome c reductase complex) subunits in clear cell renal cell carcinoma (ccRCC). In this study, the NextBio database was used to determine an expression profile of the mitochondrial complex III subunits based on published microarray studies. We observed that five out of 11 subunits of the complex III were downregulated in at least three microarray studies. The decreased mRNA expression level of UQCRFS1 and UQCRC1 in ccRCC was confirmed using PCR. Low mRNA levels UQCRC1 were also correlated with a shorter period of cancer-specific and overall survival. Furthermore, UQCRFS1 and UQCRC1 were also decreased in ccRCC on the protein level as determined using Western blotting and immunohistochemistry. UQCRC1 protein expression was also lower in ccRCC than in papillary and chromophobe subtypes. Analyzing gene expression and DNA methylation in The Cancer Genome Atlas cohort revealed an inverse correlation of gene expression and DNA methylation, suggesting that DNA hypermethylation is regulating the expression of UQCRC1 and UQCRFS1. Taken together, our data implicate that dysregulated UQCRC1 and UQCRFS1 are involved in impaired mitochondrial electron transport chain function.

UCH-L1 promotes invasion of breast cancer cells through activating Akt signaling pathway

As a de-ubiquitin enzyme, ubiquitin C-terminal hydrolase (UCH)-L1 has been shown to be overexpressed in several human cancers. However, the function of UCH-L1 in invasion of breast cancers is still unclear. Here we report that the expression of UCH-L1 is significantly higher in cancer cells with higher invasive ability. While ectopic UCH-L1 expression failed to alter cell proliferation in MCF-7 cells, it caused a significant upregulation of cellular invasion. Furthermore, siRNA mediated knockdown of UCH-L1 led to suppression of invasion in UCH-L1 overexpressing MCF-7 cells. In order to identify molecular mechanisms underlying these observations, a novel in vitro proximity-dependent biotin identification method was developed by fusing UCH-L1 protein with a bacterial biotin ligase (Escherichia coli BirA R118G, BioID). Streptavidin magnetic beads pulldown assay revealed that UCH-L1 can interact with Akt in MCF-7 cells. Pulldown assay with His tagged recombinant UCH-L1 protein and cell lysate from MCF-7 cells further demonstrated that UCH-L1 preferentially binds to Akt2 for Akt activation. Finally, we demonstrated that overexpression of UCH-L1 led to activation of Akt as evidenced by upregulation of phosphorylated Akt. Thus, these findings demonstrated that UCH-L1 promotes invasion of breast cancer cells and might serve as a potential therapeutic target for treatment of human patients with breast cancers.

Overexpression of Ubiquinol-Cytochrome c Reductase Core Protein 1 May Protect H9c2 Cardiac Cells by Binding with Zinc

In several recent studies, proteomics analyses suggest that increase of ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) is cardio-protective. However, direct evidence for this effect has not yet been obtained. Thus, the current study aimed to determine this effect and the mechanism underlying this effect. The results showed that overexpression of UQCRC1 protected H9c2 cardiac cells against in vitro simulated ischemia-reperfusion by maintaining mitochondrial membrane potential and suppressing the expression of caspase-3. These protective effects were significantly enhanced by exogenous Zn²⁺ but completely abolished by Zn²⁺-selective chelator TPEN. Furthermore, the upregulation of UQCRC1 reduced the concentration of free Zn²⁺ in mitochondria, whereas the downregulation of UQCRC1 increased the concentration of free Zn²⁺ in mitochondria. In conclusion, the overexpression of UQCRC1 can protect H9c2 cardiac cells against simulated ischemia/reperfusion, and this cardio-protective effect is likely mediated by zinc binding.

CSE1L interaction with MSH6 promotes osteosarcoma progression and predicts poor patient survival

To discover tumor-associated proteins in osteosarcoma, a quantitative proteomic analysis was performed to identify proteins that were differentially expressed between osteosarcoma and human osteoblastic cells. Through clinical screening and a functional evaluation, chromosome segregation 1-like (CSE1L) protein was found to be related to the growth of osteosarcoma cells. To date, little is known about the function and underlying mechanism of CSE1L in osteosarcoma. In the present study, we show that knockdown of CSE1L inhibits osteosarcoma growth in vitro and in vivo. By co-immunoprecipitation and RNA-seq analysis, CSE1L was found to interact with mutS homolog 6 (MSH6) and function as a positive regulator of MSH6 protein in osteosarcoma cells. A rescue study showed that decreased growth of osteosarcoma cells by CSE1L knockdown was reversed by MSH6 overexpression, indicating that the activity of CSE1L was an MSH6-dependent function. In addition, depletion of MSH6 hindered cellular proliferation in vitro and in vivo. Notably, CSE1L expression was correlated with MSH6 expression in tumor samples and was associated with poor prognosis in patients with osteosarcoma. Taken together, our results demonstrate that the CSE1L-MSH6 axis has an important role in osteosarcoma progression.

Heat shock transcription factor 1 promotes the proliferation, migration and invasion of osteosarcoma cells

OBJECTIVES

Osteosarcoma is the most commonly diagnosed primary malignancy of bone and its overall survival rate is still very low. The molecular mechanisms underlying the progression of osteosarcoma have not been clearly illuminated. Heat shock transcription factor 1 (HSF1) is a key regulator of the heat shock response and also plays important roles in many cancers, but its function in osteosarcoma remains unexplored.

MATERIALS AND METHODS

In this study, the proliferation of osteosarcoma cells was determined by Cell Counting Kit-8 assays and colony formation assays. Transwell assays were used to demonstrate the migration and invasion abilities of osteosarcoma cells. A tumour formation assay in a nude mouse model was performed to assess the effect of HSF1 on osteosarcoma cell growth in vivo. The protein levels of HSF1 were analysed with immunohistochemical staining in samples from osteosarcoma patients.

RESULTS

We demonstrated that knockdown of HSF1 reduced the proliferation, migration and invasion of osteosarcoma cells, while overexpression of HSF1 promoted the proliferation, migration and invasion of osteosarcoma cells. Furthermore, HSF1 promoted the proliferation of osteosarcoma cells in vivo. In addition, high levels of HSF1 were associated with a poor prognosis in osteosarcoma.

CONCLUSIONS

These data highlight an important role of HSF1 in proliferation, migration and invasion of osteosarcoma cells. Moreover, the expression of HSF1 was associated with prognosis in osteosarcoma.

Exploring targeted therapy of osteosarcoma using proteomics data

Despite multimodal therapeutic treatments of osteosarcoma (OS), some patients develop resistance to currently available regimens and eventually end up with recurrent or metastatic outcomes. Many attempts have been made to discover effective drugs for improving outcome; however, due to the heterogeneity of the disease, new therapeutic options have not yet been identified. This study aims to explore potential targeted therapy related to protein profiles of OS. In this review of proteomics studies, we extracted data on differentially expressed proteins (DEPs) from archived literature in PubMed and our in-house repository. The data were divided into three experimental groups, DEPs in 1) OS/OB: OS vs osteoblastic (OB) cells, 2) metastasis: metastatic vs non-metastatic sublines plus fresh tissues from primary OS with and without pulmonary metastasis, and 3) chemoresistance: spheroid (higher chemoresistance) vs monolayer cells plus fresh tissues from biopsies from good and poor responders. All up-regulated protein entities in the list of DEPs were sorted and cross-referenced with identifiers of targets of US Food and Drug Administration (FDA)-approved agents and chemical inhibitors. We found that many targets of FDA-approved antineoplastic agents, mainly a group of epigenetic regulators, kinases, and proteasomes, were highly expressed in OS cells. Additionally, some overexpressed proteins were targets of FDA-approved non-cancer drugs, including immunosuppressive and antiarrhythmic drugs. The resulting list of chemical agents showed that some transferase enzyme inhibitors might have anticancer activity. We also explored common targets of OS/OB and metastasis groups, including amidophosphoribosyltransferase (PPAT), l-lactate dehydrogenase B chain (LDHB), and pyruvate kinase M2 (PKM2) as well as the common target of all categories, cathepsin D (CTSD). This study demonstrates the benefits of a text mining approach to exploring therapeutic targets related to protein expression patterns. These results suggest possible repurposing of some FDA-approved medicines for the treatment of OS and using chemical inhibitors in drug screening tests.

Identification of specific biomarkers for gastric adenocarcinoma by ITRAQ proteomic approach

The aim of this study was to identify biomarkers for gastric cancer (GC) by iTRAQ. Using proteins extracted from a panel of 4 pairs of gastric adenocarcinoma samples (stage III-IV, Her-2 negative), we identified 10 up regulated and 9 down regulated proteins in all four pairs of GC samples compared to adjacent normal gastric tissue. The up regulated proteins are mainly involved in cell motility, while the down regulated proteins are mitochondrial enzymes involved in energy metabolism. The expression of three up regulated proteins (ANXA1, NNMT, fibulin-5) and one of the down regulated proteins (UQCRC1) was validated by Western Blot in 97 GC samples. ANXA1 was up regulated in 61.36% of stage I/II GC samples compared to matched adjacent normal gastric tissue, and its expression increased further in stage III/IV samples. Knockdown of ANXA1 by siRNA significantly inhibited GC cell migration and invasion, whereas over expression of ANXA1 promoted migration and invasion. We found decreased expression of UQCRC1 in all stages of GC samples. Our data suggest that increased cell motility and decreased mitochondrial energy metabolism are important hallmarks during the development of GC.

2,2',4,4'-Tetrabromodiphenyl ether injures cell viability and mitochondrial function of mouse spermatocytes by decreasing mitochondrial proteins Atp5b and Uqcrc1

Our object was to explore direct effects and mechanism of BDE47 on GC2 (immortalized mouse spermatocyte). GC2 were exposed to DMSO, 0.1, 1, 10, 100μM BDE47 for 48h. Cell viability was detected by trypan-blue exclusion; ultrastructure by electron-microscopy; cell cycle, mitochondrial membrane motential (MMP), reactive oxygen species (ROS) by flow-cytometry; ATP production by luminometer; Atp5b, Uqcrc1, Bcl-2 level by WB. To explore whether the decreased mitochondrial proteins play an important role in apoptosis, MMP and apoptosis were detected after Atp5b or Uqcrc1 knockdown in GC2. Results showed BDE47 reduced cell viability, caused condensation of nuclear and vacuolated mitochondria, decreased MMP and ATP, induced ROS, cell cycle arrest at S and G2/M phase, reduced Atp5b, Uqcrc1, Bcl-2 in GC2. Knockdown of Atp5b or Uqcrc1 decreased MMP, induced apoptosis in GC2. Results suggested that BDE47 reduced cell viability, injured mitochondria in spermatocytes probably by decreasing mitochondrial protein Atp5b and Uqcrc1.

Effects of Ezrin and Heat Shock Protein 70 on Apoptosis and Proliferation of Human Osteosarcoma Cells

OBJECTIVE

To investigate the influence of knocking down ezrin expression in combination with heat shock protein (HSP)-induced immune killing on the apoptosis and proliferation of mouse osteosarcoma cells.

METHODS

The HSP70 and ezrin-shRNA DNA fragments cloned into the expression vector pGFP-V-RS and the expression vectors pGFP-V-RS-shRNA and pGFP-V-RS-shRNA-HSP70 constructed and transfected into MG63 cell line, where their status was observed by fluorescent microscopy. Expression of ezrin and HSP70 was determined by RT-PCR and western blot. Changes in cell apoptosis and proliferation were assessed by flow cytometry and MTS and changes in expression of apoptosis and cell cycle-related proteins by western blot. Specific cytotoxic T lymphocytes (CTLs) were induced by HSP70 and its lethal effect on target MG63 tumor cells analyzed by MTS assay.

RESULTS

The specific vector simultaneously downregulated ezrin and upregulated HSP70. Compared with ezrin knockdown alone, simultaneous HSP70 overexpression partially recovered the promoted cellular apoptosis and proliferation suppression by induced by ezrin knockdown; however, the apoptosis rate of MG63 cells was significantly greater than that of a negative control. In addition, ezrin-shRNA and ezrin-shRNA/HSP70 promoted expression of Bax. However, expression of these agents reduces Bcl-2 and Cyclin D1. The cytotoxic effects of CTLs on target MG63 tumor cells were significantly greater in the CTL + IL-2 + HSP70 group than the CTL + IL-2 group.

CONCLUSIONS

Simultaneously knocking down ezrin and overexpressing HSP70 promotes apoptosis and inhibits proliferation of osteosarcoma cells and HSP70 induces CTL, enhancing the lethal effect on tumor cells.

Comparative proteomics analysis of human osteosarcoma by 2D DIGE with MALDI-TOF/TOF MS

Osteosarcoma (OS) is the most common primary malignant tumor of bone and the third most common cancer in childhood and adolescence. However, controversy concerning the ideal combination of chemotherapy agents ensued throughout the last quarter of the 20th century because of conflicting and often nonrandomized data. Collaborative efforts to increase understanding of the biology of osteosarcoma and the use of preclinical models to test novel protein targets will be critical to identify the path toward improving outcomes for patients. We attempted to identify potential protein markers or therapy targets of osteosarcoma and give a glance at tumorigenesis of osteosarcoma. A sensitive and accurate method was employed in comparative proteomic analysis between benign tumor and osteosarcoma. Tumor tissues obtained by open biopsy before induction chemotherapy were investigated With 2D DIGE and MALDI-TOF/TOF MS, 22 differentially expressed proteins were identified after database searching, including 8 up-regulated and 14 down-regulated proteins. We also validated the expression levels of interesting proteins(have higher Ratios(tumor/normal)) by Western blotting assay. Annotating by bioinformatic tools, we found structural and signal transduction associated proteins were in large percentage among altered level proteins. In particular, some low abundant proteins involving translation and transcription, such as EEF2(Elongation Factor 2), LUM Lumican 23 kDa Protein) and GTF2A2(Transcription Initiation Factor Iia Gamma Chain.), were firstly reported by our study comparing to previous observations. Our findings suggest that these differential proteins may be potential biomarkers for diagnosis or molecules for understanding of osteosarcoma tumorigenesis, coming with biologic, preclinical, and clinical trial efforts being described to improve outcomes for patients.

Increased cathepsin D protein expression is a biomarker for osteosarcomas, pulmonary metastases and other bone malignancies

Cancer proteomics provide a powerful approach to identify biomarkers for personalized medicine. Particularly, biomarkers for early detection, prognosis and therapeutic intervention of bone cancers, especially osteosarcomas, are missing. Initially, we compared two-dimensional gel electrophoresis (2-DE)-based protein expression pattern between cell lines of fetal osteoblasts, osteosarcoma and pulmonary metastasis derived from osteosarcoma. Two independent statistical analyses by means of PDQuest® and SameSpot® software revealed a common set of 34 differentially expressed protein spots (p < 0.05). 17 Proteins were identified by mass spectrometry and subjected to Ingenuity Pathway Analysis resulting in one high-ranked network associated with Gene Expression, Cell Death and Cell-To-Cell Signaling and Interaction. Ran/TC4-binding protein (RANBP1) and Cathepsin D (CTSD) were further validated by Western Blot in cell lines while the latter one showed higher expression differences also in cytospins and in clinical samples using tissue microarrays comprising osteosarcomas, metastases, other bone malignancies, and control tissues. The results show that protein expression patterns distinguish fetal osteoblasts from osteosarcomas, pulmonary metastases, and other bone diseases with relevant sensitivities between 55.56% and 100% at ≥87.50% specificity. Particularly, CTSD was validated in clinical material and could thus serve as a new biomarker for bone malignancies and potentially guide individualized treatment regimes.

The stromal genome heterogeneity between breast and prostate tumors revealed by a comparative transcriptomic analysis

Stromal microenvironment increases tumor cell survival, proliferation and migration, and promotes angiogenesis. In order to provide comprehensive information on the stromal heterogeneity of diverse tumors, here we employed the microarray datasets of human invasive breast and prostate cancer-associated stromals and applied Gene Set Enrichment Analysis (GSEA) to compare the gene expression profiles between them. As a result, 8 up-regulated pathways and 73 down-regulated pathways were identified in the breast tumor stroma, while 32 up-regulated pathways and 18 down-regulated pathways were identified in the prostate tumor stroma. Only 9 pathways such as tryptophan metabolism were commonly up or down regulated, but most of them (including ABC transporters) were specific for these two tumors. Several essential tumors stromal marker genes were also significantly identified. For example, CDH3 was significantly up-regulated in the stromals of both breast and prostate tumors, however EGFR was only significantly down-regulated in the stromal of breast tumor. Our study would be helpful for future therapeutic and predictive applications in breast and prostate cancers.

Piperlongumine treatment inactivates peroxiredoxin 4, exacerbates endoplasmic reticulum stress, and preferentially kills high-grade glioma cells

BACKGROUNDS

Piperlongumine, a natural plant product, kills multiple cancer types with little effect on normal cells. Piperlongumine raises intracellular levels of reactive oxygen species (ROS), a phenomenon that may underlie the cancer-cell killing. Although these findings suggest that piperlongumine could be useful for treating cancers, the mechanism by which the drug selectively kills cancer cells remains unknown.

METHODS

We treated multiple high-grade glioma (HGG) sphere cultures with piperlongumine and assessed its effects on ROS and cell-growth levels as well as changes in downstream signaling. We also examined the levels of putative piperlongumine targets and their roles in HGG cell growth.

RESULTS

Piperlongumine treatment increased ROS levels and preferentially killed HGG cells with little effect in normal brain cells. Piperlongumine reportedly increases ROS levels after interactions with several redox regulators. We found that HGG cells expressed higher levels of the putative piperlongumine targets than did normal neural stem cells (NSCs). Furthermore, piperlongumine treatment in HGG cells, but not in normal NSCs, increased oxidative inactivation of peroxiredoxin 4 (PRDX4), an ROS-reducing enzyme that is overexpressed in HGGs and facilitates proper protein folding in the endoplasmic reticulum (ER). Moreover, piperlongumine exacerbated intracellular ER stress, an effect that was mimicked by suppressing PRDX4 expression.

CONCLUSIONS

Our results reveal that the mechanism by which piperlongumine preferentially kills HGG cells involves PRDX4 inactivation, thereby inducing ER stress. Therefore, piperlongumine treatment could be considered as a novel therapeutic option for HGG treatment.

Proteomics of osteosarcoma

Osteosarcoma (OS) is the most common primary malignant tumor of bone and the third most common cancer in childhood and adolescence. Nowadays, early diagnosis, drug resistance and recurrence of the disease represent the major challenges in OS treatment. Post-genomics, and in particular proteomic technologies, offer an invaluable opportunity to address the level of biological complexity expressed by OS. Although the main goal of OS oncoproteomics is focused on diagnostic and prognostic biomarker discovery, in this review we describe and discuss global protein profiling approaches to other aspects of OS biology and pathophysiology, or to investigate the mechanism of action of chemotherapeutics. In addition, we present proteomic analyses carried out on OS cell lines as in vitro models for studying osteoblastic cell biology and the attractive opportunity offered by proteomics of OS cancer stem cells.

Surface proteomic analysis of osteosarcoma identifies EPHA2 as receptor for targeted drug delivery

BACKGROUND

Osteosarcoma (OS) is the most common bone tumour in children and adolescents. Despite aggressive therapy regimens, treatment outcomes are unsatisfactory. Targeted delivery of drugs can provide higher effective doses at the site of the tumour, ultimately improving the efficacy of existing therapy. Identification of suitable receptors for drug targeting is an essential step in the design of targeted therapy for OS.

METHODS

We conducted a comparative analysis of the surface proteome of human OS cells and osteoblasts using cell surface biotinylation combined with nano-liquid chromatography - tandem mass spectrometry-based proteomics to identify surface proteins specifically upregulated on OS cells. This approach generated an extensive data set from which we selected a candidate to study for its suitability as receptor for targeted treatment delivery to OS. First, surface expression of the ephrin type-A receptor 2 (EPHA2) receptor was confirmed using FACS analysis. Ephrin type-A receptor 2 expression in human tumour tissue was tested using immunohistochemistry. Receptor targeting and internalisation studies were conducted to assess intracellular uptake of targeted modalities via EPHA2. Finally, tissue micro arrays containing cores of human OS tissue were stained using immunohistochemistry and EPHA2 staining was correlated to clinical outcome measures.

RESULTS

Using mass spectrometry, a total of 2841 proteins were identified of which 156 were surface proteins significantly upregulated on OS cells compared with human primary osteoblasts. Ephrin type-A receptor 2 was highly upregulated and the most abundant surface protein on OS cells. In addition, EPHA2 was expressed in a vast majority of human OS samples. Ephrin type-A receptor 2 effectively mediates internalisation of targeted adenoviral vectors into OS cells. Patients with EPHA2-positive tumours showed a trend toward inferior overall survival.

CONCLUSION

The results presented here suggest that the EPHA2 receptor can be considered an attractive candidate receptor for targeted delivery of therapeutics to OS.

Minnelide reduces tumor burden in preclinical models of osteosarcoma

Osteosarcoma is the most common bone cancer in children and adolescents with a 5-year survival rate of about 70%. In this study, we have evaluated the preclinical therapeutic efficacy of the novel synthetic drug, Minnelide, a prodrug of triptolide on osteosarcoma. Triptolide was effective in significantly inducing apoptosis in all osteosarcoma cell lines tested but had no significant effect on the human osteoblast cells. Notably, Minnelide treatment significantly reduced tumor burden and lung metastasis in the orthotopic and lung colonization models. Triptolide/Minnelide effectively downregulated the levels of pro-survival proteins such as heat shock proteins, cMYC, survivin and targets the NF-κB pathway.

Mitogen-activated protein kinase pathway in osteosarcoma

AIMS

The MAPK pathway has been shown to contribute to the prognostic role and drug resistance in many cancers. In addition, the MAPK pathway was found to play a role in the aggressive behaviour of osteosarcoma (OS). We hypothesised that the expression of the MAPK pathway components may be of value in predicting the prognosis of patients with OS.

METHODS

We evaluated the expression of pan-Ras, Raf-1, pMEK1/2 and pERK1/2 in 61 OS samples using immunohistochemistry and evaluated their effect on event free survival (EFS) and overall survival (OVS).

RESULTS

pan-Ras, Raf-1, pMEK1/2 and pERK1/2 were found to be expressed in seven (11%), 36 (59%), 36 (59%) and 30 (49%) of 61 samples, respectively. Patients groups whose tumours expressed Raf-1, pMEK1/2 or pERK1/2 had a poorer clinical outcome than the group whose tumours did not express those antibodies. In addition, positive pMEK1/2 expression was associated with shorter EFS and OVS, irrespective of other prognostic factors.

CONCLUSIONS

Our results further support the findings that aberrant expression of the MAPK pathway components may be the underlying mechanism behind OS, which results in more aggressive clinical behaviour. Furthermore, there may be a decrease in EFS and OVS in OS patients who have tumours that stain positively for pMEK.

Distinct profiles of oxidative stress-related and matrix proteins in adult bone and soft tissue osteosarcoma and desmoid tumors: a proteomics study

Osteosarcomas rarely occur in older adults. Proteomics has not been reported to date in osteosarcoma occurring in the older adult population. This proteomic investigation was conducted to identify differentially expressed proteins in osteosarcoma occurring in various backgrounds from older adults. Desmoid tumors, known to recur locally but not metastasize, were also analyzed. Protein digests isolated from formalin-fixed, paraffin-embedded tumor tissue specimen representing 14 primary osteosarcomas of soft tissue and bone and 18 desmoid tumors were analyzed by high-resolution liquid chromatography-tandem mass spectrometry for protein identification and relative quantification by spectral counting. Elevated abundance levels of several proteins including heat shock protein 90 (HSP90), elastin microfibril interface-located protein 1, and clusterin were identified in osteosarcoma with slight differences in proteomic profiles. Desmoids had an abundance of collagen II and periostin only. The findings were confirmed by immunohistochemical staining for HSP90 and clusterin in the experimental samples and additionally in 16 posttherapy conventional osteosarcomas in tissue microarrays constructed from heterogeneous sarcomas and benign lesions. All osteosarcomas were positive for HSP90 and clusterin to a variable extent. One case of well-differentiated parosteal osteosarcoma was negative. Thirty of 75 other high-grade sarcomas including cases of chondrosarcoma were positive for HSP90. Low-grade and benign lesions and scars and 18 desmoid tumors had little or no expression of these proteins. HSP90 and clusterin represent candidate markers of aggressiveness in osteosarcoma occurring in older adults and may be indicative of drug resistance.

Suppression of peroxiredoxin 4 in glioblastoma cells increases apoptosis and reduces tumor growth

Glioblastoma multiforme (GBM), the most common and aggressive primary brain malignancy, is incurable despite the best combination of current cancer therapies. For the development of more effective therapies, discovery of novel candidate tumor drivers is urgently needed. Here, we report that peroxiredoxin 4 (PRDX4) is a putative tumor driver. PRDX4 levels were highly increased in a majority of human GBMs as well as in a mouse model of GBM. Reducing PRDX4 expression significantly decreased GBM cell growth and radiation resistance in vitro with increased levels of ROS, DNA damage, and apoptosis. In a syngenic orthotopic transplantation model, Prdx4 knockdown limited GBM infiltration and significantly prolonged mouse survival. These data suggest that PRDX4 can be a novel target for GBM therapies in the future.

Ubiquitin C-terminal hydrolase l1 in tumorigenesis

Ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1, aka PGP9.5) is an abundant, neuronal deubiquitinating enzyme that has also been suggested to possess E3 ubiquitin-protein ligase activity and/or stabilize ubiquitin monomers in vivo. Recent evidence implicates dysregulation of UCH-L1 in the pathogenesis and progression of human cancers. Although typically only expressed in neurons, high levels of UCH-L1 have been found in many nonneuronal tumors, including breast, colorectal, and pancreatic carcinomas. UCH-L1 has also been implicated in the regulation of metastasis and cell growth during the progression of nonsmall cell lung carcinoma, colorectal cancer, and lymphoma. Together these studies suggest UCH-L1 has a potent oncogenic role and drives tumor development. Conversely, others have observed promoter methylation-mediated silencing of UCH-L1 in certain tumor subtypes, suggesting a potential tumor suppressor role for UCH-L1. In this paper, we provide an overview of the evidence supporting the involvement of UCH-L1 in tumor development and discuss the potential mechanisms of action of UCH-L1 in oncogenesis.

Overexpression of ubiquitin carboxyl terminal hydrolase impairs multiple pathways during eye development in Drosophila melanogaster

UCH-L1 (ubiquitin carboxyl terminal hydrolase L1) is well known as an enzyme that hydrolyzes polyubiquitin at its C-terminal to release ubiquitin monomers. Although the overexpression of UCH-L1 inhibits proteasome activity in cultured cells, its biological significance in living organisms has not been clarified in detail. Here, we utilized Drosophila as a model system to examine the effects of the overexpression of dUCH, a Drosophila homologue of UCH-L1, on development. Overexpression in the eye imaginal discs induced a rough eye phenotype in the adult, at least partly resulting from the induction of caspase-dependent apoptosis followed by compensatory proliferation. Genetic crosses with enhancer trap lines marking the photoreceptor cells also revealed that the overexpression of dUCH specifically impaired R7 photoreceptor cell differentiation with a reduction in activated extracellular-signal-regulated kinase signals. Furthermore, the dUCH-induced rough eye phenotype was rescued by co-expression of the sevenless gene or the Draf gene, a downstream component of the mitogen-activated protein kinase (MAPK) cascade. These results indicate that the overexpression of dUCH impairs R7 photoreceptor cell differentiation by down-regulating the MAPK pathway. Interestingly, this process appears to be independent of its pro-apoptotic function.

Proteomic technologies for the study of osteosarcoma

Osteosarcoma is the most common primary bone cancer of children and is established during stages of rapid bone growth. The disease is a consequence of immature osteoblast differentiation, which gives way to a rapidly synthesized incompletely mineralized and disorganized bone matrix. The mechanism of osteosarcoma tumorogenesis is poorly understood, and few proteomic studies have been used to interrogate the disease thus far. Accordingly, these studies have identified proteins that have been known to be associated with other malignancies, rather than being osteosarcoma specific. In this paper, we focus on the growing list of available state-of-the-art proteomic technologies and their specific application to the discovery of novel osteosarcoma diagnostic and therapeutic targets. The current signaling markers/pathways associated with primary and metastatic osteosarcoma that have been identified by early-stage proteomic technologies thus far are also described.

Expression of UQCRC1 in primary colorectal cancer and lymph node metastases

AIM: To screen new biomarkers for colorectal cancer (CRC) by identifying differentially expressed proteins between CRC and matched normal mucosa using proteomic technology and to analyze the association of identified biomarkers with colorectal carcinogenesis, development and lymph node metastasis.

METHODS: Six pairs of fresh samples of CRC and matched normal mucosa were analyzed by two-dimensional differential gel electrophoresis (2D-DIGE) followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The expression of the identified differential protein ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) was validated in 78 cases of CRC, matched normal mucosa and lymph node metastases. The immunostaining intensity of UQCRC1 was scored. Wilcoxon signed rank test and Krukal-Wallis test were used for statistical analysis.

RESULTS: 2D-DIGE analysis showed that the intensity of a protein spot was significantly increased by 2.14 folds (P < 0.001) in CRC. This spot was confirmed to be UQCRC1 by MALDI-TOF-MS. Immunohistochemistry analysis revealed that the immunostaining intensity of UQCRC1 was significantly higher in CRC than in matched normal mucosa (2.28 ± 0.95 vs 1.81 ± 0.88, P < 0.001). However, the expression of UQCRC1 had no correlation with differentiation, TNM stage or tumor location (all P > 0.05). The intensity of UQCRC1 was significantly lower in primary CRC than in lymph node metastases (P < 0.05).

CONCLUSION: UQCRC1 may play an important role in colorectal carcinogenesis and lymph node metastases.

Post-genomics of bone metabolic dysfunctions and neoplasias

Post-genomic research on osteoblastic and osteoclastic cells, in contrast to that on many other cell types, has only been undertaken recently. Nevertheless, important information has been gained from these investigations on the mechanisms involved in osteoblast differentiation and on markers relevant for tissue regeneration and therapeutic validation of drugs, hormones and growth factors. These protein indicators may also have a diagnostic and prognostic value for bone dysfunctions and tumors. Some reviews have already focused on the application of transcriptomics and/or proteomics for exploring skeletal biology and related disorders. The main goal of the present review is to systematically summarize the most relevant post-genomic studies on various metabolic bone diseases (osteoporosis, Paget's disease and osteonecrosis), neoplasias (osteosarcoma) and metabolic conditions that indirectly affect bone tissue, such as alkaptonuria.

Ubiquitin carboxyl-terminal hydrolase 1 (UCHL1) is a potential tumour suppressor in prostate cancer and is frequently silenced by promoter methylation

Background

We have previously reported significant downregulation of ubiquitin carboxyl-terminal hydrolase 1 (UCHL1) in prostate cancer (PCa) compared to the surrounding benign tissue. UCHL1 plays an important role in ubiquitin system and different cellular processes such as cell proliferation and differentiation. We now show that the underlying mechanism of UCHL1 downregulation in PCa is linked to its promoter hypermethylation. Furthermore, we present evidences that UCHL1 expression can affect the behavior of prostate cancer cells in different ways.

Results

Methylation specific PCR analysis results showed a highly methylated promoter region for UCHL1 in 90% (18/20) of tumor tissue compared to 15% (3/20) of normal tissues from PCa patients. Pyrosequencing results confirmed a mean methylation of 41.4% in PCa whereas only 8.6% in normal tissues. To conduct functional analysis of UCHL1 in PCa, UCHL1 is overexpressed in LNCaP cells whose UCHL1 expression is normally suppressed by promoter methylation and found that UCHL1 has the ability to decrease the rate of cell proliferation and suppresses anchorage-independent growth of these cells. In further analysis, we found evidence that exogenous expression of UCHL1 suppress LNCaP cells growth probably via p53-mediated inhibition of Akt/PKB phosphorylation and also via accumulation of p27kip1 a cyclin dependant kinase inhibitor of cell cycle regulating proteins. Notably, we also observed that exogenous expression of UCHL1 induced a senescent phenotype that was detected by using the SA-ß-gal assay and might be due to increased p14ARF, p53, p27kip1 and decreased MDM2.

Conclusion

From these results, we propose that UCHL1 downregulation via promoter hypermethylation plays an important role in various molecular aspects of PCa biology, such as morphological diversification and regulation of proliferation.

Potential prognostic marker ubiquitin carboxyl-terminal hydrolase-L1 does not predict patient survival in non-small cell lung carcinoma

Background

Ubiquitin Carboxyl-Terminal Hydrolase-L1 (UCH-L1) is a deubiquitinating enzyme that is highly expressed throughout the central and peripheral nervous system and in cells of the diffuse neuroendocrine system. Aberrant function of UCH-L1 has been associated with neurological disorders such as Parkinson's disease and Alzheimer's disease. Moreover, UCH-L1 exhibits a variable expression pattern in cancer, acting either as a tumour suppressor or promoter, depending on the type of cancer. In non-small cell lung carcinoma primary tumour samples, UCH-L1 is highly expressed and is associated with an advanced tumour stage. This suggests UCH-L1 may be involved in oncogenic transformation and tumour invasion in NSCLC. However, the functional significance of UCH-L1 in the progression of NSCLC is unclear. The aim of this study was to investigate the role of UCH-L1 using NSCLC cell line models and to determine if it is clinically relevant as a prognostic marker for advanced stage disease.

Methods

UCH-L1 expression in NSCLC cell lines H838 and H157 was modulated by siRNA-knockdown, and the phenotypic changes were assessed by flow cytometry, haematoxylin & eosin (H&E) staining and poly (ADP-ribose) polymerase (PARP) cleavage. Metastatic potential was measured by the presence of phosphorylated myosin light chain (MLC2). Tumour microarrays were examined immunohistochemically for UCH-L1 expression. Kaplan-Meier curves were generated using UCH-L1 expression levels and patient survival data extracted from Gene Expression Omnibus data files.

Results

Expression of UCH-L1 was decreased by siRNA in both cell lines, resulting in increased cell death in H838 adenocarcinoma cells but not in the H157 squamous cell line. However, metastatic potential was reduced in H157 cells. Immunohistochemical staining of UCH-L1 in patient tumours confirmed it was preferentially expressed in squamous cell carcinoma rather than adenocarcinoma. However the Kaplan-Meier curves generated showed no correlation between UCH-L1 expression levels and patient outcome.

Conclusions

Although UCH-L1 appears to be involved in carcinogenic processes in NSCLC cell lines, the absence of correlation with patient survival indicates that caution is required in the use of UCH-L1 as a potential prognostic marker for advanced stage and metastasis in lung carcinoma.

Identification of potential biomarkers for giant cell tumor of bone using comparative proteomics analysis

Giant cell tumor of bone can be locally aggressive and occasionally can metastasize in the lungs. To identify new markers predictive of aggressive behavior, we analyzed five patients who developed lung metastasis and five who remained disease free for a minimum of 5 years. Using two-dimensional electrophoresis, we detected 28 differentially expressed spots. Fourteen spots were identified using mass spectrometry, including seven up-regulated and seven down-regulated in metastatic samples and classified according to functional categories. We then selected five proteins involved in cell cycle or apoptosis. Thioredoxin peroxidase, allograft inflammatory factor 1, and ubiquitin E2N had more than threefold up-regulation; glutathione peroxidase 1 had 1.9-fold up-regulation; and heat shock protein 27 showed down-regulation in metastatic samples with a very low P value. After validation and analysis of protein levels, evaluation of clinical impact was assessed in a much wider cohort of primary archival specimens. Immunodetection showed a higher frequency of thioredoxin peroxidase, allograft inflammatory factor 1, ubiquitin E2N, and glutathione peroxidase 1 overexpression in primary tumors that developed into lung metastases or that locally relapsed than in the disease-free group, with variable stain intensity and distribution. Kaplan-Meier analysis showed that high expression of glutathione peroxidase 1 was strongly related to local recurrence and metastasis, suggesting that its up-regulation may identify a subset of high-risk patients with giant cell tumor prone to receive diverse clinical management.

Comparative proteomics analysis of human osteosarcomas and benign tumor of bone

We conducted comparative proteomic analysis of osteosarcoma, with hopes of identifying the specific protein markers of osteosarcoma and improve the understanding of tumorigenesis and progression of osteosarcoma. Proteins extracted from osteosarcoma tissue and benign bone tumors, including osteoblastoma, chondroblastoma, and giant cell tumor of bone, were examined using two-dimensional gel electrophoresis followed by mass spectrometry analysis and database searches. We also validated the expression levels of interesting proteins by Western blotting assay and immunohistochemical staining. Intensity alterations of 30 spots were detected in osteosarcoma, and 18 of these spots were finally identified, including 12 up-regulated proteins and 6 down-regulated ones. The up-regulated proteins include VIM, TUBA1C, ZNF133, EZR, ACTG1, TF, and so on. The six down-regulated proteins include ADCY1, ATP5B, TUBB, RCN3, ACTB, and YWHAZ. Subsequent immunohistochemical staining and Western blotting assay for TUBA1C and ZNF133 in osteosarcoma samples confirmed the observation obtained by proteomic analysis. Our results suggest that these identified proteins may be potential biomarkers for osteosarcoma tumorigenesis and therapeutics. Aberrant expression of cytoskeletal- and microtubule-associated proteins in osteosarcoma may provide an advantage for tumor invasion and metastasis by affecting the stability of microtubule, which consequently influences the prognosis of patients.

Emerging roles of deubiquitinases in cancer-associated pathways

Deubiquitinases (DUBs) are emerging as important regulators of many pathways germane to cancer. They may regulate the stability of key oncogenes, exemplified by USP28 stabilisation of c-Myc. Alternatively they can negatively regulate ubiquitin-dependent signalling cascades such as the NF-kappaB activation pathway. We review the current literature that associates DUBs with cancer and discuss their suitability as drug targets of the future.