CEACAM6 attenuates adenovirus infection by antagonizing viral trafficking in cancer cells

The emerging roles of CEACAM6 in human cancer (Review)

Carcinoembryonic antigen (CEA)‑related cell adhesion molecule 6 (CEACAM6) is a cell adhesion protein of the CEA family of glycosyl phosphatidyl inositol anchored cell surface glycoproteins. A wealth of research has demonstrated that CEACAM6 is generally upregulated in pancreatic adenocarcinoma, breast cancer, non‑small cell lung cancer, gastric cancer, colon cancer and other cancers and promotes tumor progression, invasion and metastasis. The transcriptional expression of CEACAM6 is regulated by various factors, including the CD151/TGF‑β1/Smad3 axis, microRNA (miR)‑146, miR‑26a, miR‑29a/b/c, miR‑128, miR‑1256 and DNA methylation. In addition, the N‑glycosylation of CEACAM6 protein at Asn256 is mediated by α‑1,6‑mannosylglycoptotein 6‑β‑N‑acetylglucosaminyltransferase. In terms of downstream signaling pathways, CEACAM6 promotes tumor proliferation by increasing levels of cyclin D1 and cyclin‑dependent kinase 4 proteins. CEACAM6 can activate the ERK1/2/MAPK or SRC/focal adhesion kinase/PI3K/AKT pathways directly or through EGFR, leading to stimulation of tumor proliferation, invasion, migration, resistance to anoikis and chemotherapy, as well as angiogenesis. This article provides a review of the expression pattern, biological function and relationship with prognosis of CEACAM6 in cancer. In summary, CEACAM6 may be a valuable diagnostic biomarker and potential therapeutic target for human cancers exhibiting overexpression of CEACAM6.

CD73 controls Myosin II-driven invasion, metastasis, and immunosuppression in amoeboid pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDAC) has a very poor prognosis because of its high propensity to metastasize and its immunosuppressive microenvironment. Using a panel of pancreatic cancer cell lines, three-dimensional (3D) invasion systems, microarray gene signatures, microfluidic devices, mouse models, and intravital imaging, we demonstrate that ROCK-Myosin II activity in PDAC cells supports a transcriptional program conferring amoeboid invasive and immunosuppressive traits and in vivo metastatic abilities. Moreover, we find that immune checkpoint CD73 is highly expressed in amoeboid PDAC cells and drives their invasive, metastatic, and immunomodulatory traits. Mechanistically, CD73 activates RhoA-ROCK-Myosin II downstream of PI3K. Tissue microarrays of human PDAC biopsies combined with bioinformatic analysis reveal that rounded-amoeboid invasive cells with high CD73-ROCK-Myosin II activity and their immunosuppressive microenvironment confer poor prognosis to patients. We propose targeting amoeboid PDAC cells as a therapeutic strategy.

Enhancement of transgene expression by the β-catenin inhibitor iCRT14

The innate immune response is an essential defense mechanism that allows cells to detect pathogen-associated molecular patterns (PAMPs) like endotoxin or cytosolic DNA and then induce the expression of defensive genes that restrict the replication of viruses and other pathogens. However, the therapeutic DNA used in some gene therapy treatments can also trigger the innate immune response, which activates host cell genes that may inhibit transgene expression. The goal of this study was to enhance transgene expression by inhibiting key components of the innate immune response with small molecule inhibitors (iCRT14, curcumin, Amlexanox, H-151, SC-514, & VX-702). Most of the inhibitors significantly increased transgene (luciferase) expression at least 2-fold, but the β-catenin/TCF4 inhibitor iCRT14 showed the highest enhancement (16 to 35-fold) in multiple cell lines (PC-3, MCF7, & MB49) without significantly decreasing cellular proliferation. Alternatively, cloning a β-catenin/TCF4 binding motif (TCAAAG) into the EF1α promoter also enhanced transgene expression up to 8-fold. To further investigate the role of β-catenin/TCF4 in transgene expression, mRNA-sequencing experiments were conducted to identify host cell genes that were upregulated following transfection with PEI but down-regulated after the addition of iCRT14. As expected, transfection with plasmid DNA activated the innate immune response and upregulated hundreds (687) of defensive genes, but only 7 of those genes were down-regulated in the presence of iCRT14 (e.g., PTGS2 & PLA1A). Altogether, these results show that transgene expression can be enhanced by inhibiting the innate immune response with SMIs like iCRT14, which inhibits β-catenin/TCF4 to prevent the expression of specific host cell genes.

Co-expression of SARS-CoV-2 entry genes in the superficial adult human conjunctival, limbal and corneal epithelium suggests an additional route of entry via the ocular surface

PURPOSE

The high infection rate of SARS-CoV-2 necessitates the need for multiple studies identifying the molecular mechanisms that facilitate the viral entry and propagation. Currently the potential extra-respiratory transmission routes of SARS-CoV-2 remain unclear.

METHODS

Using single-cell RNA Seq and ATAC-Seq datasets and immunohistochemical analysis, we investigated SARS-CoV-2 tropism in the embryonic, fetal and adult human ocular surface.

RESULTS

The co-expression of ACE2 receptor and entry protease TMPRSS2 was detected in the human adult conjunctival, limbal and corneal epithelium, but not in the embryonic and fetal ocular surface up to 21 post conception weeks. These expression patterns were corroborated by the single cell ATAC-Seq data, which revealed a permissive chromatin in ACE2 and TMPRSS2 loci in the adult conjunctival, limbal and corneal epithelium. Co-expression of ACE2 and TMPRSS2 was strongly detected in the superficial limbal, corneal and conjunctival epithelium, implicating these as target entry cells for SARS-CoV-2 in the ocular surface. Strikingly, we also identified the key pro-inflammatory signals TNF, NFKβ and IFNG as upstream regulators of the transcriptional profile of ACE2+TMPRSS2+ cells in the superficial conjunctival epithelium, suggesting that SARS-CoV-2 may utilise inflammatory driven upregulation of ACE2 and TMPRSS2 expression to enhance infection in ocular surface.

CONCLUSIONS

Together our data indicate that the human ocular surface epithelium provides an additional entry portal for SARS-CoV-2, which may exploit inflammatory driven upregulation of ACE2 and TMPRSS2 entry factors to enhance infection.

Transient Inhibition of PI3Kδ Enhances the Therapeutic Effect of Intravenous Delivery of Oncolytic Vaccinia Virus

Tumor-targeting oncolytic viruses such as vaccinia virus (VV) are attractive cancer therapeutic agents that act through multiple mechanisms to provoke both tumor lysis and anti-tumor immune responses. However, delivery of these agents remains restricted to intra-tumoral administration, which prevents effective targeting of inaccessible and disseminated tumor cells. In the present study we have identified transient pharmacological inhibition of the leukocyte-enriched phosphoinositide 3-kinase δ (PI3Kδ) as a novel mechanism to potentiate intravenous delivery of oncolytic VV to tumors. Pre-treatment of immunocompetent mice with the PI3Kδ-selective inhibitor IC87114 or the clinically approved idelalisib (CAL-101), prior to intravenous delivery of a tumor-tropic VV, dramatically improved viral delivery to tumors. This occurred via an inhibition of viral attachment to, but not internalization by, systemic macrophages through perturbation of signaling pathways involving RhoA/ROCK, AKT, and Rac. Pre-treatment using PI3Kδ-selective inhibitors prior to intravenous delivery of VV resulted in enhanced anti-tumor efficacy and significantly prolonged survival compared to delivery without PI3Kδ inhibition. These results indicate that effective intravenous delivery of oncolytic VV may be clinically achievable and could be useful in improving anti-tumor efficacy of oncolytic virotherapy.

Activation of the Lysosome-Associated Membrane Protein LAMP5 by DOT1L Serves as a Bodyguard for MLL Fusion Oncoproteins to Evade Degradation in Leukemia

PURPOSE

Despite many attempts to understand mixed-lineage leukemia (MLL leukemia), effective therapies for this disease remain limited. We identified a lysosome-associated membrane protein (LAMP) family member, LAMP5, that is specifically and highly expressed in patients with MLL leukemia. The purpose of the study was to demonstrate the functional relevance and clinical value of LAMP5 in the disease.

EXPERIMENTAL DESIGN

We first recruited a large cohort of leukemia patients to validate LAMP5 expression and evaluate its clinical value. We then performed in vitro and in vivo experiments to investigate the functional relevance of LAMP5 in MLL leukemia progression or maintenance.

RESULTS

LAMP5 was validated as being specifically and highly expressed in patients with MLL leukemia and was associated with a poor outcome. Functional studies showed that LAMP5 is a novel autophagic suppressor and protects MLL fusion proteins from autophagic degradation. Specifically targeting LAMP5 significantly promoted degradation of MLL fusion proteins and inhibited MLL leukemia progression in both an animal model and primary cells. We further revealed that LAMP5 is a direct target of the H3K79 histone methyltransferase DOT1L. Downregulating LAMP5 with a DOT1L inhibitor enhanced the selective autophagic degradation of MLL oncoproteins and extended survival in vivo; this observation was especially significant when combining DOT1L inhibitors with LAMP5 knockdown.

CONCLUSIONS

This study demonstrates that LAMP5 serves as a "bodyguard" for MLL fusions to evade degradation and is the first to link H3K79 methylation to autophagy regulation, highlighting the potential of LAMP5 as a therapeutic target for MLL leukemia.

Oncolytic Viruses-Interaction of Virus and Tumor Cells in the Battle to Eliminate Cancer

Oncolytic viruses (OVs) are an emerging treatment option for many cancer types and have recently been the focus of extensive research aiming to develop their therapeutic potential. The ultimate aim is to design a virus which can effectively replicate within the host, specifically target and lyse tumor cells and induce robust, long lasting tumor-specific immunity. There are a number of viruses which are either naturally tumor-selective or can be modified to specifically target and eliminate tumor cells. This means they are able to infect only tumor cells and healthy tissue remains unharmed. This specificity is imperative in order to reduce the side effects of oncolytic virotherapy. These viruses can also be modified by various methods including insertion and deletion of specific genes with the aim of improving their efficacy and safety profiles. In this review, we have provided an overview of the various virus species currently being investigated for their oncolytic potential and the positive and negative effects of a multitude of modifications used to increase their infectivity, anti-tumor immunity, and treatment safety, in particular focusing on the interaction of tumor cells and OVs.

Oncolytic viral therapy for pancreatic cancer

Outcomes of pancreatic adenocarcinoma (PDA) remain dismal despite extensive clinical investigation. Combination chemotherapy provides modest improvements in survival above best supportive care, and immunotherapy has thus far not proven effective. Nevertheless, growing insight into antitumor immunity and the tumor microenvironment has inspired the discovery of novel agents targeting PDA. Oncolytic viruses represent an emerging class of immunotherapeutic agents that have undergone extensive preclinical investigation and warrant further investigation in well-designed clinical trials.

Enhanced Replication of Hepatitis E Virus Strain 47832c in an A549-Derived Subclonal Cell Line

Hepatitis E virus (HEV) is a human pathogen with increasing importance. The lack of efficient cell culture systems hampers systematic studies on its replication cycle, virus neutralization and inactivation. Here, several cell lines were inoculated with the HEV genotype 3c strain 47832c, previously isolated from a chronically infected transplant patient. At 14 days after inoculation the highest HEV genome copy numbers were found in A549 cells, followed by PLC/PRF/5 cells, whereas HepG2/C3A, Huh-7 Lunet BLR and MRC-5 cells only weakly supported virus replication. Inoculation of A549-derived subclone cell lines resulted in most cases in reduced HEV replication. However, the subclone A549/D3 was susceptible to lower virus concentrations and resulted in higher virus yields as compared to parental A549 cells. Transcriptome analysis indicated a downregulation of genes for carcinoembryonic antigen-related cell adhesion molecules (CEACAM) 5 and 6, and an upregulation of the syndecan 2 (SDC2) gene in A549/D3 cells compared to A549 cells. However, treatment of A549/D3 cells or A549 cells with CEACAM- or syndecan 2-specific antisera did not influence HEV replication. The results show that cells supporting more efficient HEV replication can be selected from the A549 cell line. The specific mechanisms responsible for the enhanced replication remain unknown.

Carcinoembryonic antigen-related cell adhesion molecule 6 in gastrointestinal carcinomas

Carcinoembryonic antigen-related cell adhesion molecules 6 (CEACAM6) belongs to the immunoglobulin superfamily, is overexpressed in 70% of solid tumors, and strikingly correlates with prognosis in gastrointestinal tumors. CEACAM6 participates in the development of tumors mainly by promoting tumor invasion and metastasis, resisting tumor cell anoikis, enhancing tumor drug resistance, and facilitating tumor cells to escape from the immune mechanism. In recent years, studies show that CEACAM6 has a great application potential in the diagnosis of gastrointestinal carcinomas. In this paper, we summarize the research progress of CEACAM6 in gastrointestinal carcinomas and discuss some related hot issues, with an aim to provide a theoretical foundation for the future clinical application of CEACAM6.

Lovastatin enhances adenovirus-mediated TRAIL induced apoptosis by depleting cholesterol of lipid rafts and affecting CAR and death receptor expression of prostate cancer cells

Oncolytic adenovirus and apoptosis inducer TRAIL are promising cancer therapies. Their antitumor efficacy, when used as single agents, is limited. Oncolytic adenoviruses have low infection activity, and cancer cells develop resistance to TRAIL-induced apoptosis. Here, we explored combining prostate-restricted replication competent adenovirus-mediated TRAIL (PRRA-TRAIL) with lovastatin, a commonly used cholesterol-lowering drug, as a potential therapy for advanced prostate cancer (PCa). Lovastatin significantly enhanced the efficacy of PRRA-TRAIL by promoting the in vivo tumor suppression, and the in vitro cell killing and apoptosis induction, via integration of multiple molecular mechanisms. Lovastatin enhanced PRRA replication and virus-delivered transgene expression by increasing the expression levels of CAR and integrins, which are critical for adenovirus 5 binding and internalization. Lovastatin enhanced TRAIL-induced apoptosis by increasing death receptor DR4 expression. These multiple effects of lovastatin on CAR, integrins and DR4 expression were closely associated with cholesterol-depletion in lipid rafts. These studies, for the first time, show correlations between cholesterol/lipid rafts, oncolytic adenovirus infection efficiency and the antitumor efficacy of TRAIL at the cellular level. This work enhances our understanding of the molecular mechanisms that support use of lovastatin, in combination with PRRA-TRAIL, as a candidate strategy to treat human refractory prostate cancer in the future.

Tumor cell-derived MMP3 orchestrates Rac1b and tissue alterations that promote pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) arises at the convergence of genetic alterations in KRAS with a fostering microenvironment shaped by immune cell influx and fibrotic changes; identification of the earliest tumorigenic molecular mediators evokes the proverbial chicken and egg problem. Matrix metalloproteinases (MMP) are key drivers of tumor progression that originate primarily from stromal cells activated by the developing tumor. Here, MMP3, known to be expressed in PDA, was found to be associated with expression of Rac1b, a tumorigenic splice isoform of Rac1, in all stages of pancreatic cancer. Using a large cohort of human PDA tissue biopsies specimens, both MMP3 and Rac1b are expressed in PDA cells, that the expression levels of the two markers are highly correlated, and that the subcellular distribution of Rac1b in PDA is significantly associated with patient outcome. Using transgenic mouse models, coexpression of MMP3 with activated KRAS in pancreatic acinar cells stimulates metaplasia and immune cell infiltration, priming the stromal microenvironment for early tumor development. Finally, exposure of cultured pancreatic cancer cells to recombinant MMP3 stimulates expression of Rac1b, increases cellular invasiveness, and activation of tumorigenic transcriptional profiles.

IMPLICATIONS

MMP3 acts as a coconspirator of oncogenic KRAS in pancreatic cancer tumorigenesis and progression, both through Rac1b-mediated phenotypic control of pancreatic cancer cells themselves, and by giving rise to the tumorigenic microenvironment; these findings also point to inhibition of this pathway as a potential therapeutic strategy for pancreatic cancer.

Caveolin-1 associated adenovirus entry into human corneal cells

The cellular entry of viruses represents a critical area of study, not only for viral tropism, but also because viral entry dictates the nature of the immune response elicited upon infection. Epidemic keratoconjunctivitis (EKC), caused by viruses within human adenovirus species D (HAdV-D), is a severe, ocular surface infection associated with corneal inflammation. Clathrin-mediated endocytosis has previously been shown to play a critical role in entry of other HAdV species into many host cell types. However, HAdV-D endocytosis into corneal cells has not been extensively studied. Herein, we show an essential role for cholesterol rich, lipid raft microdomains and caveolin-1, in the entry of HAdV-D37 into primary human corneal fibroblasts. Cholesterol depletion using methyl-β-cyclodextrin (MβCD) profoundly reduced viral infection. When replenished with soluble cholesterol, the effect of MβCD was reversed, allowing productive viral infection. HAdV-D37 DNA was identified in caveolin-1 rich endosomal fractions after infection. Src kinase activity was also increased in caveolin-1 rich endosomal fractions after infection, and Src phosphorylation and CXCL1 induction were both decreased in caveolin-1-/- mice corneas compared to wild type mice. siRNA knock down of caveolin-1 in corneal cells reduced chemokine induction upon viral infection, and caveolin-1-/- mouse corneas showed reduced cellular entry of HAdV-D37. As a control, HAdV-C2, a non-corneal pathogen, appeared to utilize the caveolar pathway for entry into A549 cells, but failed to infect corneal cells entirely, indicating virus and cell specific tropism. Immuno-electron microscopy confirmed the presence of caveolin-1 in HAdV-D37-containing vesicles during the earliest stages of viral entry. Collectively, these experiments indicate for the first time that HAdV-D37 uses a lipid raft mediated caveolin-1 associated pathway for entry into corneal cells, and connects the processes of viral entry with downstream proinflammatory cell signaling.

Vascular endothelial growth factor A promotes vaccinia virus entry into host cells via activation of the Akt pathway

Vaccinia virus (VV) is an enveloped DNA virus from the poxvirus family and has played a crucial role in the eradication of smallpox. It continues to be used in immunotherapy for the prevention of infectious diseases and treatment of cancer. However, the mechanisms of poxvirus entry, the host factors that affect viral virulence, and the reasons for its natural tropism for tumor cells are incompletely understood. By studying the effect of hypoxia on VV infection, we found that vascular endothelial growth factor A (VEGF-A) augments oncolytic VV cytotoxicity. VEGF derived from tumor cells acts to increase VV internalization, resulting in increased replication and cytotoxicity in an AKT-dependent manner in both tumor cells and normal respiratory epithelial cells. Overexpression of VEGF also enhances VV infection within tumor tissue in vivo after systemic delivery. These results highlight the importance of VEGF expression in VV infection and have potential implications for the design of new strategies to prevent poxvirus infection and the development of future generations of oncolytic VV in combination with conventional or biological therapies.

Collapsin response mediator protein 4 expression is associated with liver metastasis and poor survival in pancreatic cancer

BACKGROUND

Pancreatic cancer is an aggressive malignancy with one of the worst mortality rates of all cancers. Recently, collapsin response mediator proteins (CRMPs) were reported to be associated with proliferation, apoptosis, differentiation, and invasion in several cancers. However, CRMP expression and their role in pancreatic cancer have not been investigated. This study aimed to clarify the clinical significance of CRMPs in pancreatic cancer.

METHODS

Expression of crmp genes in 11 pairs of pancreatic cancer and corresponding noncancerous pancreas tissues were examined by real-time RT-PCR. Knockdown of CRMP4 expression using siRNA was examined in pancreatic cancer cell lines to determine whether CRMP4 regulates cell proliferation and invasion in vitro. Furthermore, CRMP4 protein levels in primary tumors of pancreatic cancer (n = 53) were examined by immunohistochemistry and compared with the clinicopathological features of the tumors.

RESULTS

Of all the CRMPs, only CRMP4 was differentially expressed in pancreatic cancer tissues (p = 0.008). CRMP4 knockdown using siRNA reduced cellular invasion, but did not affect proliferation. The expression of CRMP4 was detected immunohistochemically in 34 (64.2 %) of the 53 pancreatic cancer samples, and CRMP4 expression was correlated with severe venous invasion (p = 0.044), stage (p = 0.019), and liver metastasis (p = 0.021). Multivariate analyses suggested that venous invasion and CRMP4 overexpression were prognostic factors for survival.

CONCLUSIONS

Our results suggested that CRMP4 is significantly associated with poor prognosis by promoting liver metastasis and can serve as a novel therapeutic target for pancreatic cancer.

Combination of oncolytic adenovirus and dacarbazine attenuates antitumor ability against uveal melanoma cells via cell cycle block

Uveal melanoma is the most common primary intraocular malignancy in adults; however, current therapeutic modalities, including chemotherapy, have not been successful. Oncolytic viruses serve as an emerging gene therapy tool for cancer treatment because they specifically kill tumor cells while sparing normal cells. The oncolytic virus H101 has been approved by the Chinese State Food and Drug Administration for the treatment of certain malignancies. Unfortunately, the monotherapy of adenovirus has demonstrated limited efficacy in a clinical setting. Thus, novel treatment strategies in which an oncolytic virus is combined with existing chemicals are advancing toward potential clinical use. In this study, we chose the combination of oncolytic virus H101 and the alkylating agent dacarbazine (DTIC) to treat uveal melanoma cells in vitro. Our results demonstrated that the combination exerted a synergistic antitumor effect without enhanced toxicity to normal cells via a type of cell cycle block other than the induction of apoptosis. Further investigation is warranted to elucidate the specific underlying mechanisms of this co-treatment therapy. Our study suggests the viro-chemo combination therapy is feasible and is a potentially promising approach for the treatment of uveal melanoma.

Modification of the early gene enhancer-promoter improves the oncolytic potency of adenovirus 11

Oncolytic adenoviruses based on serotype 5 (Ad5) have several shortcomings, including the downregulation of its receptor in cancer cells, high prevalence of neutralizing antibodies and hepatotoxicity. Another adenoviral serotype, Ad11, could overcome these obstacles. Here, we show that human cancer cell lines express higher levels of the Ad11 receptor CD46, resulting in much better infectivity than Ad5. Surprisingly, only 36% (9/25) of the cell lines were more sensitive to Ad11- than to Ad5-mediated cytotoxicity. Investigations revealed that it was the transcription of Ad11 E1A, not CD46 expression or virus infectivity, which determined the cell's sensitivity to Ad11 killing. Ad11 E1A mRNA levels have an effect on viral DNA replication, structural protein synthesis and infectious particle production. To test the hypothesis that increased E1A transcription would lead to improved Ad11 replication in Ad5-sensitive (but Ad11-less sensitive) cells, two Ad11 mutants (Ad11-Ad5-P and Ad11-Ad5-EP) were constructed where either the E1A promoter or enhancer-promoter, respectively, was replaced by that of Ad5. Ad11-Ad5-EP demonstrated increased E1A mRNA levels and replication, together with enhanced oncolytic potency in vitro and in vivo. This effect was found in both the Ad5-sensitive and Ad11-sensitive cancer cells, broadening the range of tumors that could be effectively killed by Ad11-Ad5-EP.

Isolation of functional single domain antibody by whole cell immunization: implications for cancer treatment

Carcinoembryonic antigen related cell adhesion molecule (CEACAM) 6 is over-expressed in different types of cancer cells. In addition, it has also been implicated in some infectious diseases. Targeting this molecule by an antibody might have applications in diverse tumor models. Single domain antibody (sdAb) is becoming very useful format in antibody engineering as potential tools for treating acute and chronic disease conditions such as cancer for both diagnostic as well as therapeutic application. Generally, sdAbs with good affinity are isolated from an immune library. Discovery of a new target antigen would require a new immunization with purified antigen which is not always easy. In this study, we have isolated, by phage display, an sdAb against CEACAM6 with an affinity of 5 nM from a llama immunized with cancer cells. The antibody has good biophysical properties, and it binds to the cells expressing the target antigen. Furthermore, it reduces cancer cells proliferation in vitro and shows an excellent tumor targeting in vivo. This sdAb could be useful in diagnosis as well as therapy of CEACAM6 expressing tumors. Finally, we envisage it would be feasible to isolate good sdAbs against other interesting tumor associated antigens from this library. Therefore, this immunization method could be a general strategy for isolating sdAbs against any surface antigen without immunizing the animal with the antigen of interest each time.

A global insight into a cancer transcriptional space using pancreatic data: importance, findings and flaws

Despite the increasing wealth of available data, the structure of cancer transcriptional space remains largely unknown. Analysis of this space would provide novel insights into the complexity of cancer, assess relative implications in complex biological processes and responses, evaluate the effectiveness of cancer models and help uncover vital facets of cancer biology not apparent from current small-scale studies. We conducted a comprehensive analysis of pancreatic cancer-expression space by integrating data from otherwise disparate studies. We found (i) a clear separation of profiles based on experimental type, with patient tissue samples, cell lines and xenograft models forming distinct groups; (ii) three subgroups within the normal samples adjacent to cancer showing disruptions to biofunctions previously linked to cancer; and (iii) that ectopic subcutaneous xenografts and cell line models do not effectively represent changes occurring in pancreatic cancer. All findings are available from our online resource for independent interrogation. Currently, the most comprehensive analysis of pancreatic cancer to date, our study primarily serves to highlight limitations inherent with a lack of raw data availability, insufficient clinical/histopathological information and ambiguous data processing. It stresses the importance of a global-systems approach to assess and maximise findings from expression profiling of malignant and non-malignant diseases.

Transduction and oncolytic profile of a potent replication-competent adenovirus 11p vector (RCAd11pGFP) in colon carcinoma cells

Replication-competent adenovirus type 5 (Ad5) vectors promise to be more efficient gene delivery vehicles than their replication-deficient counterparts, and chimeric Ad5 vectors that are capable of targeting CD46 are more effective than Ad5 vectors with native fibers. Although several strategies have been used to improve gene transduction and oncolysis, either by modifying their tropism or enhancing their replication capacity, some tumor cells are still relatively refractory to infection by chimeric Ad5. The oncolytic effects of the vectors are apparent in certain tumors but not in others. Here, we report the biological and oncolytic profiles of a replication-competent adenovirus 11p vector (RCAd11pGFP) in colon carcinoma cells. CD46 was abundantly expressed in all cells studied; however, the transduction efficiency of RCAd11pGFP varied. RCAd11pGFP efficiently transduced HT-29, HCT-8, and LS174T cells, but it transduced T84 cells, derived from a colon cancer metastasis in the lung, less efficiently. Interestingly, RCAd11p replicated more rapidly in the T84 cells than in HCT-8 and LS174T cells and as rapidly as in HT-29 cells. Cell toxicity and proliferation assays indicated that RCAd11pGFP had the highest cell-killing activities in HT29 and T84 cells, the latter of which also expressed the highest levels of glycoproteins of the carcinoma embryonic antigen (CEA) family. In vivo experiments showed significant growth inhibition of T84 and HT-29 tumors in xenograft mice treated with either RCAd11pGFP or Ad11pwt compared to untreated controls. Thus, RCAd11pGFP has a potent cytotoxic effect on colon carcinoma cells.

Oncolytic-adenovirus-expressed RNA interference for cancer therapy

IMPORTANCE OF THE FIELD

RNA interference (RNAi) has generated considerable excitement for its potential cancer therapeutic applications. Because of the difficulties in delivering a large amount of siRNA to cancer cells and the short half-life of siRNA, it is important to choose an efficient delivery system for transduction of siRNA into target cells. Oncolytic adenovirus offers a better platform by virtue of its high transfection efficiency and selective replication in cancer cells.

AREAS COVERED IN THIS REVIEW

This review focuses on the synergism between oncolytic adenovirus and siRNA antitumor responses, and discusses recent progresses in oncolytic-adenovirus-expressed siRNA.

WHAT THE READER WILL GAIN

siRNA-expressing oncolytic adenovirus can generate a significantly enhanced antitumor effect through gene knockdown and viral oncolysis.

TAKE HOME MESSAGE

Due to its potency and target specificity, using siRNA delivery by oncolytic adenovirus has generated much excitement and will open new avenues for treatment of human cancer.

Iron homeostasis and the inflammatory response

Iron and its homeostasis are intimately tied to the inflammatory response. The adaptation to iron deficiency, which confers resistance to infection and improves the inflammatory condition, underlies what is probably the most obvious link: the anemia of inflammation or chronic disease. A large number of stimulatory inputs must be integrated to tightly control iron homeostasis during the inflammatory response. In order to understand the pathways of iron trafficking and how they are regulated, this article presents a brief overview of iron homeostasis. A major focus is on the regulation of the peptide hormone hepcidin during the inflammatory response and how its function contributes to the process of iron withdrawal. The review also summarizes new and emerging information about other iron metabolic regulators and effectors that contribute to the inflammatory response. Potential benefits of treatment to ameliorate the hypoferremic condition promoted by inflammation are also considered.

Integrin alphavbeta5 is a primary receptor for adenovirus in CAR-negative cells

Background

Viruses bind to specific cellular receptors in order to infect their hosts. The specific receptors a virus uses are important factors in determining host range, cellular tropism, and pathogenesis. For adenovirus, the existing model of entry requires two receptor interactions. First, the viral fiber protein binds Coxsackie and Adenovirus Receptor (CAR), its primary cellular receptor, which docks the virus to the cell surface. Next, viral penton base engages cellular integrins, coreceptors thought to be required exclusively for internalization and not contributing to binding. However, a number of studies reporting data which conflicts with this simple model have been published. These observations have led us to question the proposed two-step model for adenovirus infection.

Results

In this study we report that cells which express little to no CAR can be efficiently transduced by adenovirus. Using competition experiments between whole virus and soluble viral fiber protein or integrin blocking peptides, we show virus binding is not dependent on fiber binding to cells but rather on penton base binding cellular integrins. Further, we find that binding to low CAR expressing cells is inhibited specifically by a blocking antibody to integrin αvβ5, demonstrating that in these cells integrin αvβ5 and not CAR is required for adenovirus attachment. The binding mediated by integrin αvβ5 is extremely high affinity, in the picomolar range.

Conclusions

Our data further challenges the model of adenovirus infection in which binding to primary receptor CAR is required in order for subsequent interactions between adenovirus and integrins to initiate viral entry. In low CAR cells, binding occurs through integrin αvβ5, a receptor previously thought to be used exclusively in internalization. We show for the first time that integrin αvβ5 can be used as an alternate binding receptor.

Oncolytic Viruses for Cancer Therapy: Overcoming the Obstacles

Targeted therapy of cancer using oncolytic viruses has generated much interest over the past few years in the light of the limited efficacy and side effects of standard cancer therapeutics for advanced disease. In 2006, the world witnessed the first government-approved oncolytic virus for the treatment of head and neck cancer. It has been known for many years that viruses have the ability to replicate in and lyse cancer cells. Although encouraging results have been demonstrated in vitro and in animal models, most oncolytic viruses have failed to impress in the clinical setting. The explanation is multifactorial, determined by the complex interactions between the tumor and its microenvironment, the virus, and the host immune response. This review focuses on discussion of the obstacles that oncolytic virotherapy faces and recent advances made to overcome them, with particular reference to adenoviruses.