A real-time RT-PCR assay for the quantitative determination of adenoviral gene expression in tumor cells

Characterization of the 55-residue protein encoded by the 9S E1A mRNA of species C adenovirus

Early region 1A (E1A) of human adenovirus (HAdV) has been the focus of over 30 years of investigation and is required for the oncogenic capacity of HAdV in rodents. Alternative splicing of the E1A transcript generates mRNAs encoding multiple E1A proteins. The 55-residue (55R) E1A protein, which is encoded by the 9S mRNA, is particularly interesting due to the unique properties it displays relative to all other E1A isoforms. 55R E1A does not contain any of the conserved regions (CRs) present in the other E1A isoforms. The C-terminal region of the 55R E1A protein contains a unique sequence compared to all other E1A isoforms, which results from a frameshift generated by alternative splicing. The 55R E1A protein is thought to be produced preferentially at the late stages of infection. Here we report the first study to directly investigate the function of the species C HAdV 55R E1A protein during infection. Polyclonal rabbit antibodies (Abs) have been generated that are capable of immunoprecipitating HAdV-2 55R E1A. These Abs can also detect HAdV-2 55R E1A by immunoblotting and indirect immunofluorescence assay. These studies indicate that 55R E1A is expressed late and is localized to the cytoplasm and to the nucleus. 55R E1A was able to activate the expression of viral genes during infection and could also promote productive replication of species C HAdV. 55R E1A was also found to interact with the S8 component of the proteasome, and knockdown of S8 was detrimental to viral replication dependent on 55R E1A.

Potentiation of tumor radiotherapy by a radiation-inducible oncolytic and oncoapoptotic adenovirus in cervical cancer xenografts

The p53 tumor suppressor pathway is impaired in more than 90% of cervical cancers and cancer-derived cell lines as a result of infection by human papillomavirus (HPV). The HPV E6 oncoprotein forms complexes with p53 and promotes its degradation via ubiquitin-dependent mechanism. In our study, we attempted to improve the clinical outcomes of this combined therapy by modifying the p53-targeted adenovirus to become radiation-responsive. The antitumor adenovirus was constructed by inserting a radiation-responsive expression cassette composed of the promoter of early growth response-1 (Egr-1) and the proapoptotic protein TRAIL. We showed that the addition of adenovirus containing Egr-1/TRAIL significantly increased cell death and apoptosis caused by radiotherapy. In mice bearing xenograft tumors, intratumoral administration of the Egr-1/TRAIL adenovirus followed by radiation significantly reduced tumor growth and enhanced tumor survival. Our Egr-1/TRAIL adenoviral gene product may offer a novel "one-two punch" tumor therapy for cervical cancers not only by potentiating radiation treatment but also by preserving p53 defect-specific tumor killing of the oncolytic adenovirus.

Methods to detect infectious human enteric viruses in environmental water samples

Currently, a wide range of analytical methods is available for virus detection in environmental water samples. Molecular methods such as polymerase chain reaction (PCR) and quantitative real time PCR (qPCR) have the highest sensitivity and specificity to investigate virus contamination in water, so they are the most commonly used in environmental virology. Despite great sensitivity of PCR, the main limitation is the lack of the correlation between the detected viral genome and viral infectivity, which limits conclusions regarding the significance for public health. To provide information about the infectivity of the detected viruses, cultivation on animal cell culture is the gold standard. However, cell culture infectivity assays are laborious, time consuming and costly. Also, not all viruses are able to produce cytopathic effect and viruses such as human noroviruses have no available cell line for propagation. In this brief review, we present a summary and critical evaluation of different approaches that have been recently proposed to overcome limitations of the traditional cell culture assay and PCR assay such as integrated cell culture-PCR, detection of genome integrity, detection of capsid integrity, and measurement of oxidative damages on viral capsid protein. Techniques for rapid detection of infectious viruses such as fluorescence microscopy and automated flow cytometry have also been suggested to assess virus infectivity in water samples.

Enhanced therapeutic efficacy by simultaneously targeting two genetic defects in tumors

Targeting tumor-specific gene abnormalities has become an attractive approach in developing therapeutics to treat cancer. Overexpression of Bcl2 and mutations of p53 represent two of the most common molecular defects in tumors. In the nucleus, p53 induces cell cycle arrest, while it interacts with Bcl2 outside of the nucleus to regulate signal pathways involved in apoptosis. To potentiate antitumor activity, we tested a "double target" approach to antitumor therapy by combining H101, a recombinant oncolytic adenovirus that targets the inactive p53 in tumors, with a small interfering RNA (siBCL2) that targets Bcl2. In cell culture, the combined treatment significantly enhanced apoptosis and cytotoxicity as compared with treatment with either H101 or siBCL2 alone. In animals carrying tumor xenographs, combined H101 and siBCL2 treatment significantly inhibited tumor growth and prolonged survival. At the end of the study, all animals in the combined therapy group survived and two of the five animals showed complete eradication of their tumors. Interestingly, siBCL2 treatment increased H101 viral replication in both treated cells and tumor tissues. Simultaneously targeting two tumor-specific gene abnormalities using an oncolytic adenovirus and siRNA potentiates total antitumor activity.

Lovastatin enhances the replication of the oncolytic adenovirus dl1520 and its antineoplastic activity against anaplastic thyroid carcinoma cells

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive solid tumors and shows morphological features of a highly malignant, undifferentiated neoplasm. Patients with ATC have a poor prognosis with a mean survival time of 2-6 months; surgery, radiotherapy, and chemotherapy do not improve survival. Gene therapy approaches and oncolytic viruses have been tested for the treatment of ATC. To enhance the antineoplastic effects of the oncolytic adenovirus dl1520 (Onyx-015), we treated ATC cells with lovastatin (3-hydroxy-methylglutaryl-CoA reductase inhibitor), a drug used for the treatment of hypercholesterolemia, which has previously been reported to exert growth-inhibitory and apoptotic activity on ATC cells. Lovastatin treatment significantly increased the effects of dl1520 against ATC cells. The replication of dl1520 in ATC cells was enhanced by lovastatin treatment, and a significant increase of the expression of the early gene E1A 13 S and the late gene Penton was observed in lovastatin-treated cells. Furthermore, lovastatin treatment significantly enhanced the effects of dl1520 against ATC tumor xenografts. Lovastatin treatment could be exploited to increase the efficacy of oncolytic adenoviruses, and further studies are warranted to confirm the feasibility of the approach in ATC patients.

Paclitaxel and vincristine potentiate adenoviral oncolysis that is associated with cell cycle and apoptosis modulation, whereas they differentially affect the viral life cycle in non-small-cell lung cancer cells

Chemotherapy, including microtubule (MT)-interacting agents, can enhance the tumor-eradicating activity of replication-competent adenoviruses. The purpose of this study was to obtain more insight into the mechanism underlying this enhancement that may be exploited for the development of improved therapy. Two MT-interacting agents with opposite activity, paclitaxel (PTX) that stabilizes and vincristine (VCR) that destabilizes MTs, were found to synergistically enhance adenoviral oncolysis in non-small-cell lung cancer (NSCLC) cells. To explore the possibility that these drugs affect the viral life cycle by modulating adenoviral gene expression, we used a quantitative reverse transcription-polymerase chain reaction assay and found that PTX, but not VCR, increased the expression of E1A13S, ADP and Penton genes, which correlated with an increase in viral particle assembly and release. Next, the effect of combined treatment on cell-cycle progression was studied. Both drugs suppressed adenovirus-induced S-phase arrest and instead caused G2/M arrest, which was accompanied by an increase in apoptotic cells. Taken together, the enhancement of oncolysis by MT-interacting drugs appears not to require specific MT transport or scaffold functions. Our findings suggest that MT-interacting drug-induced cellular signals that modulate cell-cycle arrest and apoptosis are primarily on the basis of their oncolysis-enhancing activity.