Ad Library Research Articles

Using Ad-Related Network Behavior to Distinguish Ad Libraries

Mobile app ads pose a far greater security threat to users than adverts on computer browsers. This is because app developers must embed a Software Development Kit (SDK), called an ad library or ad lib for short, provided by ad networks (i.e., ad companies) into their app program, and then merge and compile it into an Android PacKage (APK) execution file. The ad lib thus becomes a part of the entire app, and shares the whole permissions granted to the app. Unfortunately, this also resulted in many security issues, such as ad libs abusing the permissions to collect and leak private data, ad servers redirecting ad requests to download malicious JavaScript from unknown servers to execute it in the background of the mobile operating system without the user’s consent. The more well-known an embedded ad lib, the safer the app may be, and vice versa. Importantly, while decompiling an APK to inspect its source code may not identify the ad lib(s), executing the app on a simulator can reveal the network behavior of the embedded ad lib(s). Ad libs exhibit different behavior patterns when communicating with ad servers. This study uses a dynamic analysis method to inspect an executing app, and plots the ad lib behavior patterns related to the advertisement into a graph. It is then determined whether or not the ad lib is from a trusted ad network using comparisons of graph similarities.

An Engineered Virus Library as a Resource for the Spectrum-wide Exploration of Virus and Vector Diversity

Adenoviruses (Ads) are large human-pathogenic double-stranded DNA (dsDNA) viruses presenting an enormous natural diversity associated with a broad variety of diseases. However, only a small fraction of adenoviruses has been explored in basic virology and biomedical research, highlighting the need to develop robust and adaptable methodologies and resources. We developed a method for high-throughput direct cloning and engineering of adenoviral genomes from different sources utilizing advanced linear-linear homologous recombination (LLHR) and linear-circular homologous recombination (LCHR). We describe 34 cloned adenoviral genomes originating from clinical samples, which were characterized by next-generation sequencing (NGS). We anticipate that this recombineering strategy and the engineered adenovirus library will provide an approach to study basic and clinical virology. High-throughput screening (HTS) of the reporter-tagged Ad library in a panel of cell lines including osteosarcoma disease-specific cell lines revealed alternative virus types with enhanced transduction and oncolysis efficiencies. This highlights the usefulness of this resource.

On Ad Library Updates in Android Apps

On Ad Library Updates in Android Apps

Analyzing Ad Library Updates in Android Apps

Because more than 90 percent of mobile apps are free, advertising on them is a key revenue source for their developers. Advertisements are served on apps through embedded specialized code called ad libraries. Unlike with other types of libraries, app developers can't ignore new ad libraries or new versions of embedded ad libraries without risking revenue loss. However, updating ad libraries incurs costs, which can become problematic as these updates become more frequent. Researchers investigated the costs of updating ad libraries and explored the frequency of ad library updates in Android apps. An analysis of numerous versions of Android apps over 12 months showed that almost half underwent ad library updates (an ad library was added, removed, or updated). Moreover, in nearly 14 percent of the app updates with at least one ad library update, no changes to the app's API occurred. This suggests that maintaining the ad libraries entailed substantial additional effort for the developers.

Abstract 3541: Therapeutic effect of CD133-targeted oncolytic adenovirus in colon cancer

Abstract CD133 (Prominin-1), a member of the transmembrane glycoprotein family is a cell surface marker cancer stem cells (CSCs) in many malignancies. In colorectal cancer, CD133 expression was correlated with recurrence, metastases and chemotherapy resistance, as well as poor survival. It is thus reasonable to develop novel therapeutic strategies to target CD133 positive cancer cells in order to attack colon cancer stem cells. We have been developing therapeutic approaches based on the oncolytic adenovirus, and have recently established a method for isolating transductionally-targeted adenovirus by high-throughput screening. In this study, in order to development for new CSCs-targeted therapeutic strategies, we isolated the CD133-specific Oncolytic Adenovirus (OAd) and tested the oncolytic activity of CD133-targeted OAd. We established the 293 cells overexpressing CD133 (293-CD133), and the fiber-modified Ad library was screened by infecting this cell line. Random sequences in the initial library started to converge after first round and resulted in a single clone (TYMLSRN) after the 4th round. CD133-targeted OAd (AdML-TYML) showed strong binding to CD133-positive cells (293-CD133 and LoVo (CD133 (+) human colon carcinoma)), not to CD133-negative cells (parental 293 and LS174T (CD133 (-) human colon carcinoma)). In addition, the anti-CD133 antibody inhibited the binding of AdML-TYML to CD133. To assess the cytopathic effect of CD133-targeted OAd, human colon cancer cell lines (LoVo and LS174T) were infected and the cytocidal effect was assessed by crystal violet staining. AdML-TYML showed strong oncolysis selectively in LoVo cells, whereas there was no effect on LS174T cells. In order to assess the in vivo function of AdML-TYML, tumor formation assay was performed. AdML-TYML infection resulted in complete blockage of the tumor formation of CD133-positive LoVo cells. 100% of the mice inoculated with non-infected LoVo cells had developed tumors, while 0% of the mice inoculated with AdML-TYML infected LoVo cells had done so. Contrarily, there was no difference between non-infected cells (100%) and infected cells (75%) in CD133-negative LS174T cells. These results indicate that CD133-targeted OAd leads to a reduction in tumor formation of CD133-positive cell lines in vivo. We focused on the CD133 as a target molecule of CSCs in colon cancer and successfully identified potent CD133-targeting OAd using high-throughput screening system. The CD133-targeted OAd exhibited selective infectivity and oncolysis to CD133-positive cells and anti-tumorigenic activity against colon cancer cells. The same approach can be applied to other cancers whose CSC marker is CD133. The ability of CSCs-targeted Ad such as CD133-targeted OAd to infect and kill CSCs has important implications for the prevention of metastases and relapses in a variety of cancers. Citation Format: Mizuho Sato, Yoshiaki Miura, Masato Yamamoto. Therapeutic effect of CD133-targeted oncolytic adenovirus in colon cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3541. doi:10.1158/1538-7445.AM2015-3541

Abstract 724: Systemic injection of fiber-redesigned oncolytic adenovirus eliminates tumors in vivo

Abstract Adenovirus (Ad) has been used as a platform of oncolytic viral agents. Unlike loco-regional therapy, systemic application of cancer gene therapy mandates different level of selectivity of gene delivery. Lack of tumor selectivity at the stage of infection has hampered the in vivo efficacy of systemic therapy. The controlled vector distribution and cancer selective transduction would overcome the obstacles for systemic delivery and enable efficient systemic treatment of cancer. AdML-VTIN was identified as a mesothelin (MSLN) targeted Ad by screening of high-diversity (109-level) Ad fiber mutant library. This AB-loop-redesigned Ad yielded a potent and selective infectivity to MSLN-positive pancreatic cancer (Panc-1) in vitro. In the examination of in vivo selectivity and anti-tumor effect, the intra-tumor injection of AdML-VTIN showed significant anti-tumor effect against Panc-1 tumors, and about half of the tumor disappeared. Contrarily, the same virus showed no anti-tumor effect in MiaPaCa-2 (MSLN-negative). Viral DNA quantitation supported the selective viral replication only in Panc-1. We compared organ distribution after intravenous injection to the nude mice with subcutaneous Panc-1 xenograft among AdML-VTIN, AdML-5WT (wild type Ad5 fiber), and AdML-GERS (against PC-3, prostate cancer cell). The liver sequestration of both AB-loop redesigned Ads were more than one order of magnitude lower than that with AdML-5WT at 1hr and 48 hrs after injection. At day 7, the viral copy number of AdML-VTIN in the tumor was more than 3 orders of magnitude higher that those with AdML-5WT. Next, systemic therapeutic effect was examined with same condition of vector distribution. In only VTIN group, tumor volume was significantly decreased, and about one-third of the tumor was eliminated at 15 days after the injection even though viral amount was pretty low (109vp/mouse). In this study, systemic injection of the AB-loop redesigned oncolytic Ad with VTIN motif that was identified by Ad library screening showed remarkable anti-tumor effect in spite of low viral amount. This new oncolytic Ad enabling systemic therapy may embody efficient treatment for pancreatic cancers which are mostly found with spread or metastatic lesions. Citation Format: Yoshiaki Miura, Mizuho Sato, Julia Davydova, Masato Yamamoto. Systemic injection of fiber-redesigned oncolytic adenovirus eliminates tumors in vivo. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 724. doi:10.1158/1538-7445.AM2014-724

Tu1874 Earlier Age of Presentation of Pancreatic Adenocarcinoma in Individuals With Chronic Pancreatitis

Systemic therapies for cancer, including pancreatic cancer, have provided only limited efficacy for patients to date. Adenovirus (Ad) has frequently been used as a backbone of oncolytic viral agents. However, unlike loco-regional therapy, systemic application of cancer gene therapy mandates different level of selectivity of gene delivery. So far, insufficient cancer selectivity at the stage of infection has greatly hampered efficacy of Ad-based therapy upon systemic administration. The controlled distribution and selective transduction of the vector would overcome the obstacles for systemic delivery and enable efficient systemic treatment of cancer. We have recently developed transductionally-targeted Ads by high-throughput screening of high-diversity (10^9-level) Ad-library. Mesothelin (MSLN) is highly overexpressed in pancreatic cancers. Ad with redesigned AB-loop targeted to MSLN (AdMLVTIN)was successfully isolated from the high throughput screening of Ad library by infectivity for MSLN-expressing 293 cells (293-MSLN). The in vitro binding of AdML-VTIN corresponded to MSLN-expression of each cell line, and the suppression of MSLN-expression with siRNA or antibody blocked the binding to MSLN-expressing cells, which indicates the vector is targeted to mesothelin. In MSLN-positive cells (Panc-1), this virus exhibited higher binding ability than that of Ad with 5/3 modified fiber which is known to exhibit highest infectivity in pancreatic cancer cells. The in vivo antitumor effect was compared in Panc-1 (MSLN-positive) and MiaPaCa-2 (MSLN-negative) subcutaneous xenografts. The injection of the MSLN-retargeted oncolytic Ad showed significant antitumor effect against Panc-1 tumors, and disappearance of tumors was observed in 4 out of 8 mice. Contrarily, the same virus showed no antitumor effect in MiaPaCa-2. Viral DNA amount in the tumors correlated to the anti-tumor effect. Upon systemic administration in the nude mice with Panc-1 subcutaneous xenografts, AdML-VTIN showed significantly lower liver sequestration compared to the wild-type Ad5, and the copy number of this retargeted virus was significantly (1000-fold) higher in the tumor. These data indicates that this vector enables efficient systemic delivery and treatment of MSLN-expressing pancreatic cancer xenografts. In this study, our MSLN-targeted Ad vector exhibited selective infectivity to MSLN-positive pancreatic cancer cells in vitro and in vivo. Moreover, this virus showed dramatically augmented delivery to the tumors and significantly reduced liver sequestration upon systemic administration. This new genetically modified Ad, which is transductionally retargeted to pancreatic cancer, may embody a next generation systemic therapy for this devastating disease.

Abstract 3308: Systemic administration of fiber redesigned infectivity-selective oncolytic adenovirus for pancreatic cancer.

Abstract Adenovirus (Ad) has frequently been used as a backbone of oncolytic viral agents, while lack of selectivity to cancer cells at the stage of infection has greatly hampered in vivo efficacy. Unlike loco-regional therapy, systemic application of cancer gene therapy mandates different level of selectivity of gene delivery. The controlled distribution and selective transduction of the vector would overcome the obstacles for systemic delivery and enable efficient systemic treatment of cancer. We have recently developed transductionally-targeted Ads by high-throughput screening of high-diversity (10ˆ9-level) Ad-library. Mesothelin (MSLN) is highly over-expressed in pancreatic cancers. Ad with redesigned AB-loop targeting MSLN, AdML-VTIN, was successfully isolated from the high throughput screening of Ad library by infectivity for MSLN-expressing 293 cells (293-MSLN). The in vitro binding of AdML-VTIN corresponded to the level of MSLN-expression and the suppression of MSLN with siRNA or antibody significantly reduced the binding to MSLN-expressing cells, which indicates that mesothelin is a receptor moiety for the isolated targeting ligand. The binding ability of this virus in Panc-1 (MSLN-positive) was higher than that of Ad with 5/3 modified fiber which is known to exhibit highest infectivity in pancreatic cancer cells. The in vivo antitumor effect was compared in Panc-1 and MiaPaCa-2 (MSLN-negative) subcutaneous xenografts. The injection of the MSLN-retargeted oncolytic Ad showed significant antitumor effect against Panc-1 tumors, and about half of the tumor disappeared. Contrarily, the same virus showed no antitumor effect in MiaPaCa-2. Viral DNA quantitation also supported the selective viral replication in Panc-1. Upon systemic administration in the nude mice with Panc-1 subcutaneous xenografts, the sequestration of AdML-VTIN to the liver was significantly lower than that of wild-type Ad5, and the copy number of this retargeted virus was significantly (1000 fold) higher in the tumor. These data indicates the systemic delivery of this vector is efficient for MSLN-expression pancreatic cancer xenografts. In this study, our MSLN-targeted Ad vector exhibited significant infectivity to MSLN-positive pancreatic cancer cells in vitro and in vivo. Moreover, this virus showed significantly reduced liver sequestration as well as dramatically augmented delivery to the tumors upon systemic administration. This new genetically modified Ad transductionally retargeted to pancreatic cancer may embody a next generation targeting for this devastating disease in clinical settings. Citation Format: Yoshiaki Miura, Joohee Han, Julia Davydova, Masato Yamamoto. Systemic administration of fiber redesigned infectivity-selective oncolytic adenovirus for pancreatic cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3308. doi:10.1158/1538-7445.AM2013-3308 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Infectivity-selective Oncolytic Adenovirus Developed by High-throughput Screening of Adenovirus-formatted Library

Adenovirus (Ad) is a potent gene-delivery vehicle and has frequently been used for designing oncolytic viruses. However, lack of selectivity on infection has hampered the achievement of sufficient in vivo efficiency. Here, we developed a novel oncolytic virus system, infectivity-selective oncolytic adenovirus (ISOAd), via direct high-throughput screening of a high-diversity targeting-ligand library in adenoviral format. Through our newly designed rescue virus system, the high-diversity Ad library carrying the random seven amino acid sequences ligand-library in the AB-loop of its fiber-knob region (5 × 10(9) diversity) was successfully generated. During the screening of this library with the cells expressing the target molecule (mesothelin, MSLN), the AB-loop sequence of the virus clones converged to one dominant sequence and a novel MSLN-targeting sequence was isolated. The virus with the isolated motif showed selective infectivity to MSLN-positive cells in vitro. In vivo, it exhibited a selective and potent antitumor effect resulted from the viral replication in MSLN-positive xenografts. The ISOAd is a novel class of oncolytic Ad, which has selectivity at the step of transduction. The selectivity at the stage of infection can open new perspectives in oncolytic Ad therapy for various diseases.

Sa1799 CEA Induces Colorectal Cancer Progression by Disrupting TGF- Signaling

A number of cancers, including pancreatic cancer, are resistant to adenovirus (Ad) infection. Genetically coded viral capsid modification has achieved higher infectivity but not much specificity. Direct selection of targeted vector from Ad library is a promising approach to overcome this issue, whereas it has not come to reality due to low diversity of library thus far. We have established a novel Ad vector generating system enabling a huge-size (>1010) Ad library and developed the oncolytic vurus stytem, Infectivity Selective Oncolytic Adenovirus (ISOAd). We hypothesize that ISOAd with redesigned AB-loop isolated by the screening of the new library system would result in a new class of oncolytic Ad with selective infectivity for the therapy of pancreatic cancer. Ad AB-loop library was screened with mesothelinexpressing 293 cells (293-MSLN) to target mesothelin (MSLN) which is highly over-expressed in pancreatic cancer, and the clones converged to one dominant clone. The binding of Ad with selected clone was analyzed with 293, Panc-1, MiaPaCa-2, A549 and 293-MSLN. The binding was significantly higher in 293-MSLN than any other cells including the Panc-1 and corresponded to the level of MSLN-expression by FACS analysis. The anti-MSLN siRNA and antibody against MSLN significantly reduced the binding to MSLN expressing cells. The binding ability of the virus with this motif in Panc-1 was higher than that of Ad with 5/3 modified fiber which is known to exhibit remarkably enhanced infectivity pancreatic cancer cells. The anti-tumor effect was analyzed In Vivo using Panc-1 (as a MSLN positive) and MiaPaCa-2 (as a MSLN negative) subcutaneous xenografts. The injection of the MSLNretargeted oncolytic adenovirus showed significant anti-tumor effect against Panc-1 tumors, and almost complete regression was observed in Panc-1 tumors. Contrarily, it didn't demonstrate anti-tumor effect as same as control group against MiaPaCa-2 tumors. The hexon immunostaining and the intratumoral viral copy number also indicated that the selective replication of retargeted adnovirus in MSLN positive pancreatic cancer, but not in MSLN negative cancer. In this study, we established MSLN retargetted ISOAd from the high throughput screening of Ad library by infectivity. The selected clone exhibited significant infectivity to MSLN positive pancreatic cancer cells In Vitro and In Vivo. This new genetically modified oncolytic adenovirus with selective infectivity to pancreatic cancer embodies a next generation targeted therapeutics for this devastating disease.

Abstract 5655: Infectivity selective oncolytic adenovirus for pancreatic cancer by redesigning the AB-loop via adenovirus library screening

Abstract A number of cancers, including pancreatic cancer, are resistant to adenovirus (Ad) infection. Genetically coded viral capsid modification has achieved increased infectivity but not much target specificity. Direct selection of targeted vector from Ad library is a promising approach to overcome this issue. We have established a novel Ad vector generating system enabling a huge-size Ad library. We hypothesize that Ad with redesigned AB-loop isolated by the screening of the new library system would result in a new class of oncolytic adenovirus with selective infectivity for the therapy of pancreatic cancer. Ad AB-loop library was screened with mesothelin-expressing 293 cells (293-MSLN) to target mesothelin (MSLN) which is highly over-expressed in pancreatic cancer, and the clones converged to one dominant clone. The binding of Ad with selected clone was analyzed with 293, Panc-1, MiaPaCa-2, A549 and 293-MSLN. The binding was significantly higher in 293-MSLN than any other cells and corresponded to the order of MSLN-expression by FACS analysis. The anti-MSLN siRNA and antibody significantly reduced the binding to MSLN expressing cells. The binding ability of the virus with this motif in Panc-1 was higher than that of Ad with 5/3 modified fiber which is known to exhibit remarkably enhanced infectivity pancreatic cancer cells. The anti-tumor effect was analyzed in vivo using Panc-1 as a MSLN-positive and MiaPaCa-2 as a MSLN-negative subcutaneous tumors. The injection of the selected clone showed significant anti-tumor effect against Panc-1 tumors, and almost complete regression of some Panc-1 tumors was observed, while it didn't demonstrate anti-tumor effect against MiaPaCa-2 tumors. The hexon immunostaining and the intratumoral viral copy number also indicated that the selected clone replicated in MSLN-positive pancreatic cancer, but not in MSLN-negative cancer. In this study, we selected MSLN targeting Ad vector from the high throughput screening of Ad library by infectivity. The selected clone exhibited significant infectivity to MSLN-positive pancreatic cancer cells in vitro and in vivo. This new genetically modified oncolytic Ad with selective infectivity to pancreatic cancer may embody next generation targeted therapeutics for this devastating disease. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5655. doi:1538-7445.AM2012-5655