Novel tumor antigens identified by autologous antibody screening of childhood medulloblastoma cDNA libraries

Coming in from the cold: overcoming the hostile immune microenvironment of medulloblastoma

Medulloblastoma is an aggressive brain tumor that occurs predominantly in children. Despite intensive therapy, many patients die of the disease, and novel therapies are desperately needed. Although immunotherapy has shown promise in many cancers, the low mutational burden, limited infiltration of immune effector cells, and immune-suppressive microenvironment of medulloblastoma have led to the assumption that it is unlikely to respond to immunotherapy. However, emerging evidence is challenging this view. Here we review recent preclinical and clinical studies that have identified mechanisms of immune evasion in medulloblastoma, and highlight possible therapeutic interventions that may give new hope to medulloblastoma patients and their families.

Immunosuppression in Medulloblastoma: Insights into Cancer Immunity and Immunotherapy

OPINION STATEMENT

Medulloblastoma (MB) is the most common pediatric brain malignancy, with a 5-year overall survival (OS) rate of around 65%. The conventional MB treatment, comprising surgical resection followed by irradiation and adjuvant chemotherapy, often leads to impairment in normal body functions and poor quality of life, especially with the increased risk of recurrence and subsequent development of secondary malignancies. The development and progression of MB are facilitated by a variety of immune-evading mechanisms such as the secretion of immunosuppressive molecules, activation of immunosuppressive cells, inhibition of immune checkpoint molecules, impairment of adhesive molecules, downregulation of the major histocompatibility complex (MHC) molecules, protection against apoptosis, and activation of immunosuppressive pathways. Understanding the tumor-immune relationship in MB is crucial for effective development of immune-based therapeutic strategies. In this comprehensive review, we discuss the immunological aspect of the brain, focusing on the current knowledge tackling the mechanisms of MB immune suppression and evasion. We also highlight several key immunotherapeutic approaches developed to date for the treatment of MB.

Investigation of PRDM10 and PRDM13 Expression in Developing Mouse Embryos by an Optimized PACT-Based Embryo Clearing Method

Recent developments in tissue clearing methods have significantly advanced the three-dimensional analysis of biological structures in whole, intact tissue, providing a greater understanding of spatial relationships and biological circuits. Nonetheless, studies have reported issues with maintaining structural integrity and preventing tissue disintegration, limiting the wide application of these techniques to fragile tissues such as developing embryos. Here, we present an optimized passive tissue clearing technique (PACT)-based embryo clearing method, initial embedding PACT (IMPACT)-Basic, that improves tissue rigidity without compromising optical transparency. We also present IMPACT-Advance, which is specifically optimized for thin slices of mouse embryos past E13.5. We demonstrate proof-of-concept by investigating the expression of two relatively understudied PR domain (PRDM) proteins, PRDM10 and PRDM13, in intact cleared mouse embryos at various stages of development. We observed strong PRDM10 and PRDM13 expression in the developing nervous system and skeletal cartilage, suggesting a functional role for these proteins in these tissues throughout embryogenesis.

Rab18 Regulates Proliferation, Invasion and Cisplatin Sensitivity Through STAT3 Signaling in Head and Neck Squamous Cell Carcinoma

Introduction

The clinical significance, biological roles and potential mechanism of Rab18 remain unknown in most human cancers, including head and neck squamous cell carcinoma (HNSCC).

Methods

We used immunohistochemistry to examine Rab18 protein expression in 112 cases of HNSCC specimens. We overexpressed and knockdown Rab18 in FaDu and Detroit562 cancer cell lines. Biological roles and mechanisms of Rab18 were examined using MTT, colony formation, Matrigel invasion assay, Western blotting, Annexin V and JC1 staining.

Results

Rab18 was upregulated in 45/112 (40.2%) cases of HNSCC tissues, which correlated with advanced T classification, positive nodal metastasis and tumor node metastasis (TNM) stage. The Oncomine and The Cancer Genome Atlas (TCGA) analyses indicated that Rab18 was elevated in human HNSCC tissues and correlated with poor patient survival. Functionally, Rab18 overexpression increased growth rate, colony numbers, cell cycle progression and invading ability in FaDu cells. Rab18 downregulated cisplatin-induced apoptosis and upregulated the mitochondrial membrane potential (Δψm). Western blot revealed that Rab18 overexpression induced epithelial-to-mesenchymal transition, with downregulation of E-cadherin and upregulation of N-cadherin, Vimentin and Twist. Rab18 overexpression also upregulated Survivin protein and Rab18 knockdown showed the opposite effects on these proteins. Treatment of STAT3 inhibitor, SH-4-54, inhibited cell invasion, increased E-cadherin and downregulated N-cadherin, Twist and Survivin. SH-4-54 also abolished the effects of BCAT1 on these proteins, as well as cell invasion.

Conclusion

In summary, our data showed that Rab18 was overexpressed in human HNSCC and functioned as an oncoprotein. Rab18 regulated HNSCC cell proliferation, invasion and cisplatin sensitivity through STAT3 signaling in HNSCC.

Multifaceted Role of PRDM Proteins in Human Cancer

The PR/SET domain family (PRDM) comprise a family of genes whose protein products share a conserved N-terminal PR [PRDI-BF1 (positive regulatory domain I-binding factor 1) and RIZ1 (retinoblastoma protein-interacting zinc finger gene 1)] homologous domain structurally and functionally similar to the catalytic SET [Su(var)3-9, enhancer-of-zeste and trithorax] domain of histone methyltransferases (HMTs). These genes are involved in epigenetic regulation of gene expression through their intrinsic HMTase activity or via interactions with other chromatin modifying enzymes. In this way they control a broad spectrum of biological processes, including proliferation and differentiation control, cell cycle progression, and maintenance of immune cell homeostasis. In cancer, tumor-specific dysfunctions of PRDM genes alter their expression by genetic and/or epigenetic modifications. A common characteristic of most PRDM genes is to encode for two main molecular variants with or without the PR domain. They are generated by either alternative splicing or alternative use of different promoters and play opposite roles, particularly in cancer where their imbalance can be often observed. In this scenario, PRDM proteins are involved in cancer onset, invasion, and metastasis and their altered expression is related to poor prognosis and clinical outcome. These functions strongly suggest their potential use in cancer management as diagnostic or prognostic tools and as new targets of therapeutic intervention.

Dendritic cells transduced with glioma-expressed antigen 2 recombinant adenovirus induces specific cytotoxic lymphocyte response and anti-tumor effect in mice

Introduction

Glioma is an aggressive common cancer with high mortality worldwide. Up to date, the effective medical therapeutical strategy is limited. Numerous previous studies have indicated that glioma-expressed antigen 2 (GLEA2) might be an attractive prognostic glioma biomarker.

Methods

In this experiment, dendritic cells (DCs) transduced with GLEA2 recombinant adenovirus were utilized to generate cytotoxic lymphocytes (CTLs) in vitro. Additionally, trimera mice were immunized with the transduced DCs to generate CTLs in vivo.

Results

The data demonstrated that GLEA2 transduced DCs could effectively generate specific CTL response against glioma without lysing autologous lymphocytes. Moreover, GLEA2 transduced DCs significantly attenuated the tumor growth and prolonged the life span of tumor bearing mice.

Conclusions

These findings suggested that DCs transduced with GLEA2 recombinant adenovirus could generate effective CTL mediated anti-tumor response, and might represent insight in glioma therapy.

The spatial correspondence and genetic influence of interhemispheric connectivity with white matter microstructure

Microscopic features (that is, microstructure) of axons affect neural circuit activity through characteristics such as conduction speed. To what extent axonal microstructure in white matter relates to functional connectivity (synchrony) between brain regions is largely unknown. Using MRI data in 11,354 subjects, we constructed multivariate models that predict functional connectivity of pairs of brain regions from the microstructural signature of white matter pathways that connect them. Microstructure-derived models provided predictions of functional connectivity that explained 3.5% of cross-subject variance on average (ranging from 1-13%, or r = 0.1-0.36) and reached statistical significance in 90% of the brain regions considered. The microstructure-function relationships were associated with genetic variants, co-located with genes DAAM1 and LPAR1, that have previously been linked to neural development. Our results demonstrate that variation in white matter microstructure predicts a fraction of functional connectivity across individuals, and that this relationship is underpinned by genetic variability in certain brain areas.

Rab18 overexpression promotes proliferation and chemoresistance through regulation of mitochondrial function in human gastric cancer

Background

Dysregulation of Rab18 has been implicated in human cancers. However, its clinical significance and biological function in gastric cancer have not been investigated.

Methods

We examined Rab18 expression in gastric cancer tissues using immunohistochemistry. We used SNU-1 and AGS cell lines for plasmid and siRNA transfection respectively. MTT, colony formation assay, cell cycle analysis, matrigel invasion, wound healing assay, AnnexinV/PI analysis and western blotting were used to examine the biological effect and mechanism of Rab18 in gastric cancer cell lines.

Results

Rab18 protein expression was upregulated in gastric cancer tissues and this correlated with advanced stage and poor prognosis. Rab18 overexpression promoted proliferation in vitro and in vivo. Cell cycle analysis showed that Rab18 overexpression upregulated, while its depletion downregulated S phase percentage. Matrigel invasion and wound healing assays indicated that Rab18 positively regulated SNU-1 cell invasion and migration while its knockdown inhibited AGS cell invasion and migration. Rab18 maintained cell viability and downregulated apoptosis after cisplatin treatment, with upregulated mitochondrial membrane potential and downregulated mitochondrial reactive oxygen species (ROS) production. Rab18 overexpression upregulated p-Rb, survivin while downregulated cytochrome c, cleaved caspase-3 and cleaved PARP.

Conclusion

In conclusion, our results indicate that Rab18 promoted gastric cancer growth and chemoresistance, possibly through regulation of mitochondrial function and survivin.

Identification of genes and pathways potentially related to PHF20 by gene expression profile analysis of glioblastoma U87 cell line

Background

Glioblastoma is the most common and aggressive brain tumor associated with a poor prognosis. Plant homeodomain finger protein 20 (PHF20) is highly expressed in primary human gliomas and its expression is associated with tumor grade. However, the molecular mechanism by which PHF20 regulates glioblastoma remains poorly understood.

Methods

Genome wide gene expression analysis was performed to identify differentially expressed genes (DEGs) in U87 cells with PHF20 gene knockdown. Gene ontology (GO) and pathway enrichment analyses were performed to investigate the functions and pathways of DEGs. Pathway-net and signal-net analyses were conducted to identify the key genes and pathways related to PHF20.

Results

Expression of 540 genes, including FEN1 and CCL3, were significantly altered upon PHF20 gene silencing. GO analysis results showed that DEGs were significantly enriched in small molecule metabolic and apoptotic processes. Pathway analysis indicated that DEGs were mainly involved in cancer and metabolic pathways. The MAPK, apoptosis and p53 signaling pathways were identified as the hub pathways in the pathway network, while PLCB1, NRAS and PIK3 s were hub genes in the signaling network.

Conclusions

Our findings indicated that PHF20 is a pivotal upstream regulator. It affects the occurrence and development of glioma by regulating a series of tumor-related genes, such as FEN1, CCL3, PLCB1, NRAS and PIK3s, and activation of apoptosis signaling pathways. Therefore, PHF20 might be a novel biomarker for early diagnosis, and a potential target for glioblastoma therapies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-017-0459-x) contains supplementary material, which is available to authorized users.

A Systemic Analysis of Transcriptomic and Epigenomic Data To Reveal Regulation Patterns for Complex Disease

Integrating diverse genomics data can provide a global view of the complex biological processes related to the human complex diseases. Although substantial efforts have been made to integrate different omics data, there are at least three challenges for multi-omics integration methods: (i) How to simultaneously consider the effects of various genomic factors, since these factors jointly influence the phenotypes; (ii) How to effectively incorporate the information from publicly accessible databases and omics datasets to fully capture the interactions among (epi)genomic factors from diverse omics data; and (iii) Until present, the combination of more than two omics datasets has been poorly explored. Current integration approaches are not sufficient to address all of these challenges together. We proposed a novel integrative analysis framework by incorporating sparse model, multivariate analysis, Gaussian graphical model, and network analysis to address these three challenges simultaneously. Based on this strategy, we performed a systemic analysis for glioblastoma multiforme (GBM) integrating genome-wide gene expression, DNA methylation, and miRNA expression data. We identified three regulatory modules of genomic factors associated with GBM survival time and revealed a global regulatory pattern for GBM by combining the three modules, with respect to the common regulatory factors. Our method can not only identify disease-associated dysregulated genomic factors from different omics, but more importantly, it can incorporate the information from publicly accessible databases and omics datasets to infer a comprehensive interaction map of all these dysregulated genomic factors. Our work represents an innovative approach to enhance our understanding of molecular genomic mechanisms underlying human complex diseases.

Functional Genomics Identifies Tis21-Dependent Mechanisms and Putative Cancer Drug Targets Underlying Medulloblastoma Shh-Type Development

We have recently generated a novel medulloblastoma (MB) mouse model with activation of the Shh pathway and lacking the MB suppressor Tis21 (Patched1^+/-/Tis21^KO ). Its main phenotype is a defect of migration of the cerebellar granule precursor cells (GCPs). By genomic analysis of GCPs in vivo, we identified as drug target and major responsible of this defect the down-regulation of the promigratory chemokine Cxcl3. Consequently, the GCPs remain longer in the cerebellum proliferative area, and the MB frequency is enhanced. Here, we further analyzed the genes deregulated in a Tis21-dependent manner (Patched1^+/-/Tis21 wild-type vs. Ptch1^+/-/Tis21 knockout), among which are a number of down-regulated tumor inhibitors and up-regulated tumor facilitators, focusing on pathways potentially involved in the tumorigenesis and on putative new drug targets. The data analysis using bioinformatic tools revealed: (i) a link between the Shh signaling and the Tis21-dependent impairment of the GCPs migration, through a Shh-dependent deregulation of the clathrin-mediated chemotaxis operating in the primary cilium through the Cxcl3-Cxcr2 axis; (ii) a possible lineage shift of Shh-type GCPs toward retinal precursor phenotype, i.e., the neural cell type involved in group 3 MB; (iii) the identification of a subset of putative drug targets for MB, involved, among the others, in the regulation of Hippo signaling and centrosome assembly. Finally, our findings define also the role of Tis21 in the regulation of gene expression, through epigenetic and RNA processing mechanisms, influencing the fate of the GCPs.

Spontaneous cellular and humoral tumor antigen responses in patients with uveal melanoma

Antigens that may be involved in the immune response to uveal melanoma have not been identified. Cellular and humoral responses to melanoma differentiation antigens, as well as to BRCA1-associated protein 1 (BAP1) and α-enolase, alterations of which are associated with metastatic disease, were examined in patients with uveal melanoma. Blood was collected from 66 patients with primary and 13 patients with metastatic uveal melanoma. These included 11 patients treated with immunotherapy. Peripheral blood mononuclear cells were stimulated with gp100, MART-1, tyrosinase, NY-ESO-1, BAP1, and α-enolase peptides and/or proteins, and cytokine production was assessed by bead array or enzyme-linked immunosorbent assay. Autoantibodies to the protein were assessed by enzyme-linked immunosorbent assay. A cellular or humoral response to one or more of the antigens was observed in 23% of the primary and 62% of the metastatic patients tested. Th1 and Th2 cellular and humoral responses to gp100, MART-1, and tyrosinase were observed in primary and metastatic patients. Cellular responses to NY-ESO-1 were not observed nor were Th17-associated responses. Cellular and humoral responses to BAP1 and α-enolase were also observed, predominantly in primary patients with tumor monosomy-3 and in metastatic patients. Individual patients treated with immunotherapy developed new reactivity to MART-1, tyrosinase, and/or α-enolase. Patients with primary and metastatic uveal melanomas manifest spontaneous immune responses to melanoma differentiation antigens, BAP1, and α-enolase. Both Th1-associated and Th2-associated responses are observed and can be modified by therapy. These results may help the development and monitoring of immunotherapy and studies of immune surveillance in uveal melanoma.

PRDM14 promotes the migration of human non-small cell lung cancer through extracellular matrix degradation in vitro

Background:

As a novel molecular markerof non-small cell lung cancer (NSCLC), PRDI-BF1 and RIZ homology domain containing protein 14 (PRDM14) is over-expressed in NSCLC tumor tissues. Extracellular matrix degradation mediated by the balance between matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) is one of the most important mechanism in lung cancer metastasis. This study aimed to determine if PRDM14 promoted the migration of NSCLC cells through extracellular matrix degradation mediated by change of MMP/TIMP expression.

Methods:

The expression of PRDM14 was down-regulated in human cell line A 549 after transfection with lentiviral vector-mediated short-hairpin ribonucleic acids (shRNAs) which targeted the PRDM14 promoter. Cellular migration of shRNA-infected cells was detected by a scratch wound healing assay and transwell cell migration assay. Expression levels of MMP1, MMP2, TIMP1, and TIMP2 were measured by quantitative real-time polymerase chain reaction (RT-PCR).

Results:

Migration of PRDM14-shRNA-infected cells was significantly inhibited relative to control cells as measured by the scratch wound healing (P < 0.05) and transwell cell migration assays (P < 0.01). The expression of MMP1 in A549 cells infected by PRDM14-shRNA was down-regulated significantly (P < 0.01), whereas the expression of TIMP1 and TIMP2 was up-regulated significantly (P < 0.01).

Conclusions:

PRDM14 accelerates A549 cells migration in vitro through extracellular matrix degradation. PRDM14 is considered as a potential therapeutic target in metastatic NSCLC.

MicroRNA-30b/c inhibits non-small cell lung cancer cell proliferation by targeting Rab18

BACKGROUND

MicroRNAs (miRNAs) are small noncoding RNAs that post-transcriptional regulate gene expression in a variety of cancers. Increasing evidences indicate that miR-30 expression is down-regulated in numerous human cancers including non-small cell lung cancer (NSCLC) which hypothesizes that miR-30 may play an important role in tumorigenesis. The aim of this study was to investigate the target gene of miR-30 and its roles in tumor growth of NSCLC.

METHODS

Luciferase reporter assays were employed to validate regulation of a putative target of miR-30. The effect of miR-30 on endogenous levels of this target were subsequently confirmed via Western blot (WB). Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to determine the expression level of miR-30 in NSCLC specimens and adjacent non-tumor tissues. MTT assays were conducted to explore the impact of miR-30 overexpression on the proliferation of human NSCLC cells.

RESULTS

Both miR-30b and miR-30c (miR-30b/c) were found having target site in same region of Rab18 mRNA. Luciferase assays using a reporter carrying a putative miR-30b/c target site in the coding DNA sequence (CDS) region of Rab18 revealed that miR-30b/c directly targeted Rab18. Overexpression of miR-30b/c led to down-regulation of Rab18 in A549 and H23 cells at protein levels but not mRNA levels. Down-regulation of miR-30b/c and up-regulation of Rab18 protein levels were detected in NSCLC specimens compared with adjacent non-tumor tissues. Overexpression of miR-30b/c suppressed NSCLC cells growth. Knockdown of Rab18 by siRNA significantly inhibited the proliferation of NSCLC cells.

CONCLUSIONS

We demonstrated that miR-30b/c was down-regulated in NSCLC specimens compared with adjacent non-tumor tissues. miR-30b/c directly targeted and down-regulated Rab18 expression and inhibited NSCLC cells proliferation. These data indicated that miR-30b/c could serve as a tumor suppressor gene involved in NSCLC pathogenesis.

Clinical significance of Ankyrin repeat domain 12 expression in colorectal cancer

Background

Ankyrin repeat domain 12 (ANKRD12), is encoding a 224 kDa nuclear protein and most conserved at its N-terminal ankyrin repeats region and the C-terminal co-activator interacting domain. The aim of this study was to investigate the ANKRD12 mRNA expression in colorectal cancer (CRC) tumor tissues and the normal adjacent mucosa and its potential relevance to clinicopathological characteristics and prognosis.

Methods

Surgical specimens of tumor tissues (n = 68) and adjacent normal mucosa (n = 51) were obtained from CRC patients. The ANKRD12 mRNA expression was measured by quantitative real time reverse transcriptase polymerase chain reaction. The relationship between ANKRD12 mRNA expression and clinicopathological features was analyzed by appropriate statistics. Kaplan–Meier analysis and Cox proportional hazards regression models were used to investigate the correlation between ANKRD12 expression and prognosis of CRC patients.

Results

The relative mRNA expression of ANKRD12 were significantly lower in CRC tumor tissues than in the normal adjacent mucosa (P < 0.001), and the cases with low ANKRD12 expression showed a higher frequency of liver metastasis (P = 0.015). Kaplan–Meier analysis indicated that patients (CRC without liver metastasis) with low ANKRD12 expression had poor overall survival (P = 0.041). Multivariate analysis showed that low ANKRD12 expression was an independent predictor of overall survival.

Conclusion

This study revealed that ANKRD12 mRNA were down regulated in CRC tumor tissues and low ANKRD12 expression was correlated with liver metastasis and poor survival of CRC patients.

RNA protein interaction in neurons

Neurons have their own systems for regulating RNA. Several multigene families encode RNA binding proteins (RNABPs) that are uniquely expressed in neurons, including the well-known neuron-specific markers ELAV and NeuN and the disease antigen NOVA. New technologies have emerged in recent years to assess the function of these proteins in vivo, and the answers are yielding insights into how and why neurons may regulate RNA in special ways-to increase cellular complexity, to localize messenger RNA (mRNA) spatially, and to regulate their expression in response to synaptic stimuli. The functions of such restricted neuronal proteins are likely to be complemented by more widely expressed RNABPs that may themselves have developed specialized functions in neurons, including Argonaute/microRNAs (miRNAs). Here we review what is known about such RNABPs and explore the potential biologic and neurologic significance of neuronal RNA regulatory systems.

Biomarkers of pediatric brain tumors

Background and Need for Novel Biomarkers: Brain tumors are the leading cause of death by solid tumors in children. Although improvements have been made in their radiological detection and treatment, our capacity to promptly diagnose pediatric brain tumors in their early stages remains limited. This contrasts several other cancers where serum biomarkers such as cancer antigen (CA) 19-9 and CA 125 facilitate early diagnosis and treatment.

AIM

The aim of this article is to review the latest literature and highlight biomarkers which may be of clinical use in the common types of primary pediatric brain tumor.

METHODS

A PubMed search was performed to identify studies reporting biomarkers in the bodily fluids of pediatric patients with brain tumors. Details regarding the sample type [serum, cerebrospinal fluid (CSF), or urine], biomarkers analyzed, methodology, tumor type, and statistical significance were recorded.

RESULTS

A total of 12 manuscripts reporting 19 biomarkers in 367 patients vs. 397 controls were identified in the literature. Of the 19 biomarkers identified, 12 were isolated from CSF, 2 from serum, 3 from urine, and 2 from multiple bodily fluids. All but one study reported statistically significant differences in biomarker expression between patient and control groups.

CONCLUSION

This review identifies a panel of novel biomarkers for pediatric brain tumors. It provides a platform for the further studies necessary to validate these biomarkers and, in addition, highlights several techniques through which new biomarkers can be discovered.

Hepatitis B virus X protein upregulates oncogene Rab18 to result in the dysregulation of lipogenesis and proliferation of hepatoma cells

Hepatitis B virus X protein (HBx) contributes to the development of hepatocellular carcinoma (HCC) through inducing dysregulation of lipogenesis. However, the mechanism by which HBx induces the abnormal lipogenesis is not well known. In this study, we report that the oncogene Rab18, a member of Ras family, enhances the HBx-induced hepatocarcinogenesis through inducing dysregulation of lipogenesis and proliferation. Our data showed that the expression levels of Rab18 were positively associated with those of HBx in clinical HCC tissues. HBx was able to upregulate the expression of Rab18 in p21-HBx transgenic mice and hepatoma cell lines. Next, we identified the mechanism by which HBx upregulated Rab18. The results demonstrated that cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) were able to stimulate Rab18 promoter through activating transcription factor activator protein 1 (AP-1) and cyclic adenosine 3',5'-monophosphate response element-binding (CREB). In addition, we identified another pathway that HBx activated Rab18. We found that miR-429 was able to directly target the 3' untranslated region of Rab18, suggesting that Rab18 is one of the target genes of miR-429. Then, we found that HBx was able to downregulate miR-429 in hepatoma cells. The oil red O staining showed that HBx resulted in the dysregulation of lipogenesis through Rab18. Moreover, Rab18 contributed to the HBx-enhanced proliferation of hepatoma cells in vitro and in vivo. HBx enhances hepatocarcinogenesis through leading to the dysregulation of lipogenesis and proliferation of hepatoma cells, involving two pathways such as HBx/COX-2/5-LOX/AP-1/CREB/Rab18 and HBx/miR-429/Rab18.

The Prdm family: expanding roles in stem cells and development

Members of the Prdm family are characterized by an N-terminal PR domain that is related to the SET methyltransferase domain, and multiple zinc fingers that mediate sequence-specific DNA binding and protein-protein interactions. Prdm factors either act as direct histone methyltransferases or recruit a suite of histone-modifying enzymes to target promoters. In this way, they function in many developmental contexts to drive and maintain cell state transitions and to modify the activity of developmental signalling pathways. Here, we provide an overview of the structure and function of Prdm family members and discuss the roles played by these proteins in stem cells and throughout development.

Preliminary study of thyroid and colon cancers-associated antigens and their cognate autoantibodies as potential cancer biomarkers

BACKGROUND

Autoantibodies, which are produced against tumor-associated antigens, are potential tumor markers and attract a growing interest for cancer detection, differential diagnostics and prognosis.

OBJECTIVE

To evaluate the diagnostic significance of 40 antigens identified by immunoscreening of cDNA libraries from thyroid and colon cancers by allogenic screening with different tumor types patients' sera.

METHOD

Plaque-spot serological assay.

RESULTS

Increased frequency of antibody response in sera of cancer patients compared with that of healthy donors was shown toward 14 antigens, 8 of which (CG016, BTN3A3, FKBP4, XRCC4, TSGA2, ACTR1A, FXYD3 and CTSH) have revealed exclusively cancer-related serological profile.

CONCLUSION

Allogenic screening of 40 SEREX-antigens with sera from cancer patients and healthy donors allowed us to reveal 14 antigens with potential diagnostic significance. These antigens and their cognate autoantibodies could be considered as valuable targets for further analysis as potential cancer biomarkers.

Boswellic acid induces epigenetic alterations by modulating DNA methylation in colorectal cancer cells

Accumulating evidence suggests that chemopreventive effects of some dietary polyphenols may in part be mediated by their ability to influence epigenetic mechanisms in cancer cells. Boswellic acids, derived from the plant Boswellia serrata, have long been used for the treatment of various inflammatory diseases due to their potent anti-inflammatory activities. Recent preclinical studies have also suggested that this compound has anti-cancer potential against various malignancies. However, the precise molecular mechanisms underlying their anti-cancer effects remain elusive. Herein, we report that boswellic acids modulate DNA methylation status of several tumor suppressor genes in colorectal cancer (CRC) cells. We treated RKO, SW48 and SW480 CRC cell lines with the active principle present in boswellic acids, acetyl-keto-β-boswellic acid (AKBA). Using genome-wide DNA methylation and gene expression microarray analyses, we discovered that AKBA induced a modest genome-wide demethylation that permitted simultaneous re-activation of the corresponding tumor suppressor genes. The quantitative methylation-specific PCR and RT-PCR validated the gene demethylation and re-expression in several putative tumor suppressor genes including SAMD14 and SMPD3. Furthermore, AKBA inhibited DNMT activity in CRC cells. Taken together, these results lend further support to the growing notion that anti-cancer effect of boswellic acids may in part be due to its ability to demethylate and reactivate methylation-silenced tumor suppressor genes. These results suggest that not only boswellic acid might be a promising epigenetic modulator in the chemoprevention and treatment of CRC, but also provide a rationale for future investigations on the usefulness of such botanicals for epigenetic therapy in other human malignancies.

Crystal structures of the Tudor domains of human PHF20 reveal novel structural variations on the Royal Family of proteins

The human PHD finger protein 20 (PHF20) is a putative transcription factor. While little is known about its cognate cellular role, antibodies against PHF20 are present in sera from patients with hepatocellular carcinoma, glioblastoma and childhood medulloblastula. PHF20 comprises two N-terminal Tudor domains, a central C2H2-link zinc finger domain and a C-terminal zinc-binding PHD domain, and is a component of some MLL methyltransferase complexes. Here, we report the crystal structures of the N-terminal Tudor domains of PHF20 and highlight the novel structural features of each domain. We also confirm previous studies suggesting that the second Tudor domain of PHF20 exhibits preference for dimethylated histone substrates.

Medulloblasoma: challenges for effective immunotherapy

For medulloblastoma patients, the current therapeutic paradigm of surgery followed by radiation and chemotherapy can lead to long-term remission. However, the sequelae of treatment can be very debilitating, particularly in young children. Immunotherapy is an attractive treatment approach to optimize the targeting of tumor cells while sparing the vulnerable surrounding brain that is still developing in children. Understanding the relationship between medulloblastoma and the immune system is critical to develop effective immunologic-based treatment strategies for these patients. This review focuses on current knowledge of tumor immunology and the factors that contribute to the lack of immune system recognition of these tumors. The specificity of tumor antigens present in medulloblastoma is also discussed along with a summary of early clinical immunotherapy results.

PRDM proteins: important players in differentiation and disease

The PRDM family has recently spawned considerable interest as it has been implicated in fundamental aspects of cellular differentiation and exhibits expanding ties to human diseases. The PRDMs belong to the SET domain family of histone methyltransferases, however, enzymatic activity has been determined for only few PRDMs suggesting that they act by recruiting co-factors or, more speculatively, confer methylation of non-histone targets. Several PRDM family members are deregulated in human diseases, most prominently in hematological malignancies and solid cancers, where they can act as both tumor suppressors or drivers of oncogenic processes. The molecular mechanisms have been delineated for only few PRDMs and little is known about functional redundancy within the family. Future studies should identify target genes of PRDM proteins and the protein complexes in which PRDM proteins reside to provide a more comprehensive understanding of the biological and biochemical functions of this important protein family.

[Relationship between the expression of PRDM14 in non-small cell lung cancer and the clinicopathologic characteristics]

背景与目的

锌指蛋白转录抑制因子(positive regulatory domain zinc finger protein, PRDM)是一个有关人类肿瘤形成的转录调节因子家族，在细胞分化和恶性变中发挥重要作用。PRDM14是PRDM家族的成员之一。本研究的目的是检测PRDM14在非小细胞肺癌组织中的表达情况并探讨其与非小细胞肺癌的临床病理因素的关系。

方法

采用免疫组织化学方法检测70例非小细胞肺癌标本和7例癌旁组织中PRDM14的表达。采用Western blot方法检测42例非小细胞肺癌组织和癌旁肺组织中PRDM14蛋白的表达。

结果

7例癌旁肺组织中PRDM14弱表达，在70例非小细胞肺癌组织标本中，有8例为PRDM14阴性表达(11.43%)，9例为PRDM14弱阳性表达(12.86%)，36例PRDM14阳性表达(51.43%)，有17例PRDM14强阳性表达(24.29%)，PRDM14的表达情况与非小细胞肺癌的分化程度(P=0.046)和组织学类型(P=0.047)有关，PRDM14在高分化腺癌、鳞癌中表达最高，在中分化腺癌、鳞癌中表达次之，在低分化腺癌、鳞癌表达最低，PRDM14在腺癌中的表达高于鳞癌。Western blot结果表明PRDM14的蛋白在癌旁肺组织和肺腺癌、鳞癌组织的表达水平存在显著差异，PRDM14在非小细胞肺癌组织中的表达水平高于癌旁肺组织(P＜0.001)，而且与非小细胞肺癌的分化程度有关(P=0.017)，在高、中分化腺癌、鳞癌中的表达高于在低分化腺癌、鳞癌中的表达。

结论

PRDM14在癌旁肺组织中低表达，在非小细胞肺癌组织中高表达，其表达水平与非小细胞肺癌的分化、组织学类型有关，可能在非小细胞肺癌的发生发展中发挥作用。

The dynamic Rab11-FIPs

The Rab11-FIPs (Rab11-family interacting proteins; also known as FIPs) constitute an evolutionarily conserved protein family that act as effector molecules for multiple Rab and Arf (ADP-ribosylation factor) GTPases. They were initially characterized by their ability to bind Rab11 subfamily members via a highly-conserved C-terminal RBD (Rab11-binding domain). Resolution of the crystal structure of Rab11 in complex with FIPs revealed that the RBD mediates homodimerization of the FIP molecules, creating two symmetrical interfaces for Rab11 binding and leading to the formation of a heterotetrameric complex between two FIP and two Rab11 molecules. The FIP proteins are encoded by five genes and alternative splicing has been reported. Based on primary structure, the FIPs were subcategorized into two classes: class I [Rip11, FIP2 and RCP (Rab-coupling protein)] and class II (FIP3 and FIP4). Recent studies have identified the FIPs as key players in the regulation of multiple distinct membrane trafficking events. In this mini-review, we summarize the Rab11-FIP field and discuss, at molecular and cellular levels, the recent findings on FIP function.

Regulation of vertebrate nervous system alternative splicing and development by an SR-related protein

Alternative splicing is a key process underlying the evolution of increased proteomic and functional complexity and is especially prevalent in the mammalian nervous system. However, the factors and mechanisms governing nervous system-specific alternative splicing are not well understood. Through a genome-wide computational and expression profiling strategy, we have identified a tissue- and vertebrate-restricted Ser/Arg (SR) repeat splicing factor, the neural-specific SR-related protein of 100 kDa (nSR100). We show that nSR100 regulates an extensive network of brain-specific alternative exons enriched in genes that function in neural cell differentiation. nSR100 acts by increasing the levels of the neural/brain-enriched polypyrimidine tract binding protein and by interacting with its target transcripts. Disruption of nSR100 prevents neural cell differentiation in cell culture and in the developing zebrafish. Our results thus reveal a critical neural-specific alternative splicing regulator, the evolution of which has contributed to increased complexity in the vertebrate nervous system.

Cloning and Characterization of a novel splice variant of humanRab18gene (RAB18)

Rab GTPase proteins are a kind of small GTP-binding proteins, which functions mainly focus on regulating interacellular trafficking pathways during vesicular transport. To date, 60 distinct human RAB proteins have been identified. RAB18 gene is discovered from endothelial cells. Its function is considered as endosomes and plasma membrane recycling. Research indicates RAB18 may relate to inflammation and some kinds of tumor. Here we report a splice variant of RAB18, which is 2571 bp in length and has an open reading frame coding a predicted 235 amino-acids protein. RT-PCR shows that the cDNA has different expression pattern with RAB18 and is highly expressed in testis.

Ankyrin repeats-containing cofactors interact with ADA3 and modulate its co-activator function

ANCO (ankyrin repeats-containing cofactor)-1 and ANCO-2 are a family of unique transcriptional co-regulators with dual properties: they interact with both the co-activators and the co-repressors [Zhang, Yeung, Li, Tsai, Dinh, Wu, Li and Chen (2004) J. Biol. Chem. 279, 33799-33805]. Specifically, ANCO-1 is thought to recruit HDACs (histone deacetylases) to the p160 co-activator to repress transcriptional activation by nuclear receptors. In the present study, we provide new evidence to suggest further that ANCO-1 and ANCO-2 also interact with the co-activator ADA3 (alteration/deficiency in activation 3). The interaction occurs between the conserved C-terminal domain of ANCO-1 and the N-terminal transactivation domain of ADA3. Several subunits of the P/CAF {p300/CBP [CREB (cAMP-response-element-binding protein)-binding protein]-associated factor} complex, including ADA3, ADA2alpha/beta and P/CAF, showed co-localization with ANCO-1 nuclear dots, indicating an in vivo association of ANCO-1 with the P/CAF complex. Furthermore, a transient reporter assay revealed that both ANCO-1 and ANCO-2 repress ADA3-mediated transcriptional co-activation on nuclear receptors, whereas ANCO-1 stimulated p53-mediated transactivation. These data suggest that ADA3 is a newly identified target of the ANCO proteins, which may modulate co-activator function in a transcription-factor-specific manner.

Rab18 is reduced in pituitary tumors causing acromegaly and its overexpression reverts growth hormone hypersecretion

CONTEXT

Rab proteins regulate the sequential steps of intracellular membrane transport. Alterations of these GTPases and their associated proteins are emerging as the underlying cause for several human diseases involving dysregulated secretory activities.

OBJECTIVE

Herein we investigated the role of Rab18, which negatively regulates hormone secretion by interacting with secretory granules, in relation to the altered functioning of tumoral pituitary somatotropes causing acromegaly.

PATIENTS

A total of 18 patients diagnosed with pituitary tumors causing acromegaly (nine patients) or nonfunctioning adenomas (nine patients) underwent endoscopic transsphenoidal surgery. Adenomas were subsequently processed to evaluate Rab18 production in relation to GH secretion.

RESULTS

We found that somatotropinoma cells are characterized by a high secretory activity concomitantly with a remarkably reduced Rab18 expression (15%) and protein content levels (30%), as compared with cells from nonfunctioning pituitary adenomas derived from patients with normal or reduced GH plasma levels (100%). Furthermore, immunoelectron microscopy revealed that Rab18 association with the surface of GH-containing secretory granules was significantly lower in somatotropes from acromegalies than nonfunctioning pituitary adenomas. Finally, we provide evidence that modulation of Rab18 gene expression can revert substantially the hypersecretory activity of cells because Rab18 overexpression reduced by 40% the capacity of cells from acromegalies to respond to GHRH stimulation.

CONCLUSION

These results suggest that molecular alterations affecting individual components of the secretory granule traffic machinery can contribute to maintain a high level of GH in plasma. Accordingly, Rab18 constitutes a valuable target as a diagnostic, prognostic, and/or therapeutic tool for human acromegaly.

Increased seroreactivity to glioma-expressed antigen 2 in brain tumor patients under radiation

BACKGROUND

Surgery and radiation are the mainstays of therapy for human gliomas that are the most common primary brain tumors. Most recently, cell culture and animal studies provided the first convincing evidence that radiation not only eliminates tumor cells, but also modulates the immune response and likely improves anti-tumor immunotherapy.

METHODOLOGY/PRINCIPAL FINDINGS

We present an in vivo study that analyzes the effects of radiation on the immune response in tumor patients. As readout system, we utilized the reactivity of glioma patients' sera against antigen GLEA2 as the most frequent antigen immunogenic in glioblastoma patients. We established an ELISA assay to analyze reactivity of 24 glioblastoma patients over a period of several months. As control we used 30 sera from healthy donors as well as 30 sera from lung cancer patients. We compared the course of GLEA2 seroreactivity at different times prior, during and after radiation. The GLEA2 seroreactivity was increased by the time of surgery, decreased after surgery, increased again under radiation, and slightly decreased after radiation.

CONCLUSIONS/SIGNIFICANCE

Our results provide in vivo evidence for an increased antibody response against tumor antigens under radiation. Antigens that become immunogenic with an increased antibody response as result of radiation can serve as ideal targets for immunotherapy of human tumors.

Targeting serum antibody for cancer diagnosis: a focus on colorectal cancer

The ability of the immune system to magnify the appearance of disease by generating relatively large amounts of antibody in response to small amounts of disease makes it a natural biosensor, and serum antibodies have emerged as promising biomarkers for the detection of cancer. This review summarizes recent progress in targeting serum antibodies for cancer diagnosis, with a particular focus on colorectal cancer (CRC). Several serum antibodies have been detected at increased levels in CRC patients, including p53, carcinoembryonic antigen, Ras, topoisomerase II-alpha, histone deacetylase 3 and 5, ubiquitin C-terminal hydrolase L3, tropomyosin and cyclin B1. As each antibody is only present in a limited proportion of patients (usually < 40%), a combination of serum antibodies that defines the 'immunological signature' of cancer needs to be developed. High-throughput methods to identify new serum antibodies for cancer diagnosis are also reviewed.

Subcellular localization of ankyrin repeats cofactor-1 regulates its corepressor activity

The ankyrin repeats cofactor-1 (ANCO-1) was recently identified as a novel nuclear receptor corepressor that regulates receptor-mediated transcription through interactions with p160 coactivators and histone deacetylases. Interestingly, exogenously expressed ANCO-1 is localized at distinct subnuclear domains. The relevance of these subnuclear domains and the mechanisms of nucleocytoplasmic translocation of ANCO-1 have not been determined. We report here the identification of an N-terminal signaling motif that is essential for both nuclear/subnuclear localization and transcription corepressor function of ANCO-1. This N-terminal motif at residues 80-86 of ANCO-1 constitutes a classical nuclear localization signal (NLS1). Disruption of NLS1 causes complete cytoplasmic accumulation of the full-length ANCO-1, and abolishes its corepressor function on receptor-mediated transcription. A second NLS (NLS2) is found at the C-terminal residues 2384-2390; however, its disruption abolishes only nuclear localization of isolated C-terminal fragments. We also identify a leucine-rich nuclear export signal (NES) at residues 2415-2424 of ANCO-1, and show that both the NLSs and NES sequences are capable of mediating nuclear import and export of heterologous protein, respectively. In addition, attachment of the NES sequence to a transcription factor impairs its activation function. These results suggest that ANCO-1 subnuclear localization is regulated by both nuclear import and export signals, and that proper subcellular localization of ANCO-1 is essential for its corepressor function.

Tudor, MBT and chromo domains gauge the degree of lysine methylation

The post-translational modification of histones regulates many cellular processes, including transcription, replication and DNA repair. A large number of combinations of post-translational modifications are possible. This cipher is referred to as the histone code. Many of the enzymes that lay down this code have been identified. However, so far, few code-reading proteins have been identified. Here, we describe a protein-array approach for identifying methyl-specific interacting proteins. We found that not only chromo domains but also tudor and MBT domains bind to methylated peptides from the amino-terminal tails of histones H3 and H4. Binding specificity observed on the protein-domain microarray was corroborated using peptide pull-downs, surface plasma resonance and far western blotting. Thus, our studies expose tudor and MBT domains as new classes of methyl-lysine-binding protein modules, and also demonstrates that protein-domain microarrays are powerful tools for the identification of new domain types that recognize histone modifications.

JAMP, a Jun N-terminal kinase 1 (JNK1)-associated membrane protein, regulates duration of JNK activity

We report the identification and characterization of JAMP (JNK1 [Jun N-terminal kinase 1]-associated membrane protein), a predicted seven-transmembrane protein that is localized primarily within the plasma membrane and associates with JNK1 through its C-terminal domain. JAMP association with JNK1 outcompetes JNK1 association with mitogen-activated protein kinase phosphatase 5, resulting in increased and prolonged JNK1 activity following stress. Elevated expression of JAMP following UV or tunicamycin treatment results in sustained JNK activity and a higher level of JNK-dependent apoptosis. Inhibition of JAMP expression by RNA interference reduces the degree and duration of JNK activation and concomitantly the level of stress-induced apoptosis. Through its regulation of JNK1 activity, JAMP emerges as a membrane-anchored regulator of the duration of JNK1 activity in response to diverse stress stimuli.

Integrin Trafficking and the Control of Cell Migration

In the late 1980s and early 1990s, the observation that certain integrin heterodimers are continually internalized from the plasma membrane into endosomal compartments and subsequently recycled back to the cell surface indicated that the endocytic and recycling pathways have the potential to exert minute-to-minute control over integrin function. This insight has prompted others to study the regulation of integrin trafficking in more detail. This review aims to summarize the findings of studies revealing the molecular mechanisms controlling integrin traffic, particularly those providing indications as to how these processes contribute to cell migration and tumour cell invasiveness.

Identification of a novel family of ankyrin repeats containing cofactors for p160 nuclear receptor coactivators

Members of the p160 nuclear receptor coactivators interact with liganded nuclear receptors to enhance transcription of target genes. Here we identify a novel family of ankyrin repeats containing cofactors (ANCOs) that interact with the p160 coactivators. ANCO-1 binds to the conserved Per-Arnt-Sim (PAS) region of the p160 coactivators. It encodes a large nuclear protein with five ankyrin repeats, and parts of its sequences have been reported as nasopharyngeal carcinoma susceptibility protein and medulloblastoma antigen. Immunofluorescence staining reveals discrete nuclear foci of ANCO-1 that are distinct from known nuclear structures. Intriguingly, ANCO-1 also colocalizes and interacts with histone deacetylases. Transient reporter gene assay shows that ANCO-1 expression inhibits ligand-dependent transactivation by both steroid and nonsteroid nuclear receptors. Taken together, we have identified a novel family of ankyrin repeats containing cofactors that may recruit histone deacetylases to the p160 coactivators/nuclear receptor complex to inhibit ligand-dependent transactivation.

Discovery and immunologic validation of new antigens for therapeutic cancer vaccines

Immunotherapy using both active and passive approaches is increasingly being used as a modality to treat human cancer. The last decade has seen a tremendous burst of activity in antigen discovery in cancer, and many new targets have now been identified for both monoclonal antibody therapy and active immunization. In addition, advances have been made in our understanding of the immune response against cancer and how new vaccine vectors, such as poxviruses, alphaviruses and bacterial vectors, can be used to overcome some of the traditional hurdles (e.g. self-tolerance and immune suppression in cancer patients) that have hindered the generation of effective antitumor immune responses. Improvements in genomics technology in the area of DNA microarrays and differential display and subtractive hybridization together with a new wave of mass spectrometry-based proteomics tools, as well as more sensitive assays to validate the immunoreactivity of new antigens, have all accelerated the rate of new antigen discovery in cancer. This rapid progress should initiate a major paradigm shift in how we treat cancer within the next 10 years, where, instead of being a novelty, the combination of targeted T cell-based vaccines and antiangiogenesis therapies will be routinely combined with traditional chemotherapy. The successful combination of these approaches will change the face of cancer from a relatively acute, life-threatening disease to a manageable chronic disorder with long survival times.