Efficient generation of double heterologous promoter controlled oncolytic adenovirus vectors by a single homologous recombination step in Escherichia coli

A Comprehensive Exploration of Bioluminescence Systems, Mechanisms, and Advanced Assays for Versatile Applications

Bioluminescence has been a fascinating natural phenomenon of light emission from living creatures. It happens when the enzyme luciferase facilitates the oxidation of luciferin, resulting in the creation of an excited-state species that emits light. Although there are many bioluminescent systems, few have been identified. D-luciferin-dependent systems, coelenterazine-dependent systems, Cypridina luciferin-based systems, tetrapyrrole-based luciferins, bacterial bioluminescent systems, and fungal bioluminescent systems are natural bioluminescent systems. Since different bioluminescence systems, such as various combinations of luciferin-luciferase pair reactions, have different light emission wavelengths, they benefit industrial applications such as drug discovery, protein-protein interactions, in vivo imaging in small animals, and controlling neurons. Due to the expression of luciferase and easy permeation of luciferin into most cells and tissues, bioluminescence assays are applied nowadays with modern technologies in most cell and tissue types. It is a versatile technique in a variety of biomedical research. Furthermore, there are some investigated blue-sky research projects, such as bioluminescent plants and lamps. This review article is mainly based on the theory of diverse bioluminescence systems and their past, present, and future applications.

Personalizing Oncolytic Virotherapy for Glioblastoma: In Search of Biomarkers for Response

Simple Summary

Glioblastoma (GBM) is the most frequent and aggressive primary brain tumor. Despite multimodal treatment, the prognosis of GBM patients remains very poor. Oncolytic virotherapy is being evaluated as novel treatment for this patient group and clinical trials testing oncolytic viruses have shown impressive responses, albeit in a small subset of GBM patients. Obtaining insight into specific tumor- or patient-related characteristics of the responding patients, may in the future improve response rates. In this review we discuss factors related to oncolytic activity of the most widely applied oncolytic virus strains as well as potential biomarkers and future assays that may allow us to predict response to these agents. Such biomarkers and tools may in the future enable personalizing oncolytic virotherapy for GBM patients.

Abstract

Oncolytic virus (OV) treatment may offer a new treatment option for the aggressive brain tumor glioblastoma. Clinical trials testing oncolytic viruses in this patient group have shown promising results, with patients achieving impressive long-term clinical responses. However, the number of responders to each OV remains low. This is thought to arise from the large heterogeneity of these tumors, both in terms of molecular make-up and their immune-suppressive microenvironment, leading to variability in responses. An approach that may improve response rates is the personalized utilization of oncolytic viruses against Glioblastoma (GBM), based on specific tumor- or patient-related characteristics. In this review, we discuss potential biomarkers for response to different OVs as well as emerging ex vivo assays that in the future may enable selection of optimal OV for a specific patient and design of stratified clinical OV trials for GBM.

Development of novel vaccine vectors: Chimpanzee adenoviral vectors

Adenoviral vector has been employed as one of the most efficient means against infectious diseases and cancer. It can be genetically modified and armed with foreign antigens to elicit specific antibody responses and T cell responses in hosts as well as engineered to induce apoptosis in cancer cells. The chimpanzee adenovirus-based vector is one kind of novel vaccine carriers whose unique features and non-reactivity to pre-existing human adenovirus neutralizing antibodies makes it an outstanding candidate for vaccine research and development. Here, we review the different strategies for constructing chimpanzee adenoviral vectors and their applications in recent clinical trials and also discuss the oncolytic virotherapy and immunotherapy based on chimpanzee adenoviral vectors.

Enhanced antitumor efficacy of a novel oncolytic adenovirus combined with temozolomide in the treatment of melanoma in vivo

PURPOSE

The aim of this study was to investigate the effect of Ki67-ZD55-IL-24 with temozolomide (TMZ) against melanoma in mice.

METHODS

Seventy-eight mice with subcutaneous injection of A375 cells (2 × 10(6)) into the right flank were randomized to receive phosphate buffered saline (PBS), Ki67-ZD55, Ki67-ZD55-IL-24, TMZ, TMZ + Ki67-ZD55, and TMZ + Ki67-ZD55-IL-24. Six mice were killed in each group 10 days after intervention for detecting IL-24 mRNA and protein expression. The remaining mice were monitored to draw the body weight change curve and tumor growth curve, and killed 30 days after intervention. Tumors were excised and weighted. The morphology of tumor tissues was determined by hematoxylin and eosin (HE) staining, and the apoptosis index and rate of apoptotic cells were determined by TUNEL assay and AnnexinV-FITC/PI double staining, respectively.

RESULTS

The Ki67-ZD55-IL-24-treated group generated much more reactive oxygen species than the untreated group. There was no significant difference in IL-24 expression between Ki67-ZD55-IL-24 and TMZ + Ki67-ZD55-IL-24 groups. Immunohistochemical analysis and Western blot revealed that both the Ki67-ZD55 and Ki67-ZD55-IL-24 could significantly reduce the expression of MGMT. Toxicity assessments demonstrated that mice in the three groups that received TMZ exhibited significant body weight loss following treatment. HE staining showed that TMZ + Ki67-ZD55-IL-24 group had much fewer karyokinesis in the tumors, compared with other groups. The apoptosis index of tumor tissues and the rate of apoptotic cells were significantly higher in TMZ + Ki67-ZD55-IL-24 group than in other groups (all P < 0.05).

CONCLUSIONS

These findings indicate this novel strategy holds promising potentials for treatment of malignant melanoma.

High-yield heterologous expression of wild type and mutant Ca(2+) ATPase: Characterization of Ca(2+) binding sites by charge transfer

High-yield heterologous SERCA1 (Ca(2+) ATPase) expression was obtained in COS-1 cells infected with recombinant adenovirus vector (rAdSERCA). Higher transcription and expression were obtained in the presence of a His(6) tag at the amino terminus, as compared with a His(6) tag at the carboxyl SERCA terminus, or no tag. The expressed protein was targeted extensively to intracellular membranes. Optimal yield of functional Ca(2+) ATPase corresponded to 10% of total protein, with phosphoenzyme levels, catalytic turnover and Ca(2+) transport identical with those of native SERCA1. This recombinant membrane-bound (detergent-free) enzyme was used for characterization of Ca(2+) binding at the two specific transmembrane sites (ATP-free) by measurements of net charge transfer upon Ca(2+) binding to the protein, yielding cooperative isotherms (K(1)=5.9+/-0.5x10(5) M(-1) and K(2)=5.7+/-0.3x10(6) M(-1)). Non-cooperative binding of only one Ca(2+), and loss of ATPase activation, were observed following E309 mutation at site II. On the other hand, as a consequence of the site II mutation, the affinity of site I for Ca(2+) was increased (K=4.4+/-0.2x10(6) M(-1)). This change was due to a pK(a) shift of site I acidic residues, and to contributions of oxygen functions from empty site II to Ca(2+) binding at site I. No charge movement was observed following E771Q mutation at site I, indicating no Ca(2+) binding to either site. Therefore, calcium occupancy of site I is required to trigger cooperative binding to site II and catalytic activation. In the presence of millimolar Mg(2+), the charge movement upon addition of Ca(2+) to WT ATPase was reduced by 50%, while it was reduced by 90% when Ca(2+) was added to the E309Q/A mutants, demonstrating that competitive Mg(2+) binding can occur at site I but not at site II.

Ligand-based targeted therapy for cancer tissue

BACKGROUND

Limited accessibility of drugs to the tumor tissues, the requirement of high doses, intolerable cytotoxicity, the development of multiple drug resistance and non-specific targeting are obstacles to the clinical use of cancer drugs and cancer therapy.

OBJECTIVE

Drug delivery through carrier systems to cancerous tissue is no longer simply wrapping up cancer drugs in a new formulation for different routes of delivery, rather the focus is on targeted cancer therapy.

METHODS

This review summarizes the exploitation of drug-loaded nanocarrier conjugates with various targeting moieties for the delivery and targeting of anticancer drugs and describes the current status of and challenges in the field of nanocarrier-aided drug delivery and drug targeting.

CONCLUSION

The discovery of targeting ligand to cancer cells and the development of ligand-targeted therapy will help us to improve therapeutic efficacy and reduce side effects. Unlike other forms of therapy, it will allow us to maintain quality of life for patients, while efficiently attacking the cancer tissue. It indicates that ligands have a pivotal role in cancer cell targeting.

A novel A33 promoter-based conditionally replicative adenovirus suppresses tumor growth and eradicates hepatic metastases in human colon cancer models

PURPOSE

A33 antigen is a membrane-bound protein expressed in intestinal epithelium that is overexpressed in 95% of primary and metastatic colorectal carcinomas but is absent in most epithelial tissues and tumor types. We hypothesized that A33 promoter might be useful in the design of a conditionally replicative adenovirus for the treatment of colorectal cancer (CRC).

EXPERIMENTAL DESIGN

We cloned an A33 promoter fragment (A33Pr) that extends from -105 to +307 bp. Using luciferase activity as a reporter gene, we showed that A33Pr was active in CRC cell lines. We next constructed a conditionally replicative adenovirus named AV22EL where E1A was placed under the control of A33Pr. The tumor-specific oncolytic effect of AV22EL was investigated both in vitro and in vivo.

RESULTS

AV22EL induced specific in vitro lysis of human CRC cell lines that expressed A33 and have negligible lytic capacity on cells that lacked or had minimal A33 expression, including normal human colonic cells. In vivo, a marked reduction of tumor growth and increased long-term survival rates were observed in nude mice xenografted with s.c. CRC tumors. Combination with 5-fluorouracil induced an additive effect in vitro with no toxic effects in vivo. Remarkably, AV22EL completely eliminated established hepatic metastases in >90% of mice and restored hepatic function according to biochemical parameters. Its systemic administration induced E1A expression only in the hepatic metastasis but not in normal organs.

CONCLUSIONS

These data show that AV22EL is a stringently regulated and potent oncolytic agent for the treatment of CRC.

A simplified in vitro ligation approach to clone an E1B55k-deleted double-targeted conditionally-replicative adenovirus

BACKGROUND

Construction of conditionally-replicative Adenovirus (CRAd) is complex and time-consuming. While homologous recombination (HR) using a two-plasmid system in bacteria is commonly used to generate CRAds, alternative methods may be required when HR fails. Previously, in vitro ligation has been suggested to facilitate construction of E1/E3-deleted, replication-incompetent Ad vectors. However, in vitro ligation has only rarely been used to generate CRAds and may be a complex procedure for molecular biologists who are not experts in the field.

METHODS AND RESULTS

A modified in vitro ligation approach was developed to construct a double-targeted, E1B55k-deleted CRAd. The method allowed the incorporation of a tumor-specific promoter, e.g. the heat-shock protein 70 (hsp70) promoter, upstream of E1a, deletion of the E1B55k gene, and HR-free cloning of the recombined E1Delta55k gene into the Ad genome. The genetic structure of the CRAd was confirmed using restriction analysis and PCR. The replication rate of the hsp70E1Delta55k CRAd was 1.5-2% of Ad without E1Delta55k deletion.

CONCLUSION

A 3-step cloning approach can generate a double-targeted, E1B55k-deleted CRAd using a straight-forward, modified in vitro ligation procedure.

Improved glioblastoma treatment with Ad5/35 fiber chimeric conditionally replicating adenoviruses

Adenovirus type 5 (Ad5)-based vectors have been used in clinical trials for glioblastoma treatment, but the capacity of Ad5 to infect human glioma cells was questioned. Seeking to improve the adenovirus transduction, we tested four Ad5-based vectors differing only in their fiber gene on permanent and short-term cultures of glioblastoma cells. A wild-type fiber Ad5 vector (Ad5.Luc) was compared to an RGD integrin-binding motif-containing fiber adenovirus (AdlucRGD) and the two fiber chimeras Ad5/3 and Ad5/35, with vector binding redirected to the Ad3 or Ad35 receptor, respectively. Compared to Ad5, the transduction of the tested short-term glioblastoma cultures with the vector Ad5/35.Luc, AdlucRGD and Ad5/3.Luc was enhanced by approximately 72%, approximately 13% and approximately 2%, respectively. To limit adenovirus spread, we aimed to develop conditionally replicative Ad5/35 vectors by targeting the expression of the essential E1 and E4 genes; in addition, some vectors had the E1Delta24 deletion. We analyzed eleven promoters for their activity in glioblastoma cells and determined the specificity of eight replicative adenovirus vectors in vitro. We evaluated the most promising vectors with E1/E4 under the control of the GFAP/Ki67 or E2F-1/COX-2 promoters, and the native Ad5 or the chimeric Ad5/35 fiber for their antineoplastic activity in a subcutaneous and intracranial glioblastoma xenograft model. Animals treated with the Ad5/35-based vectors showed significantly smaller tumors and longer survival than those treated with the homologous Ad5 vectors; no significant toxicity was observed in the intracranial model. Our data suggest that Ad5/35-based vectors are promising tools for glioblastoma treatment.

Evaluation of twenty-one human adenovirus types and one infectivity-enhanced adenovirus for the treatment of malignant melanoma

Advanced melanoma is associated with poor prognosis warranting the development of new therapeutics, such as oncolytic adenoviruses for immunovirotherapy. Since this approach critically depends on efficient transduction of targeted tumor cells, we screened a panel of 22 different adenovirus types for their internalization efficiency in melanoma cells. We demonstrated that the virions of Ad35, Ad38, and Ad3 have significantly higher internalization efficiency in melanoma cells than Ad5, so far the only adenovirus type used in clinical trials for melanoma. Therefore, we developed a conditionally replication-competent Ad5-based vector with the Ad35 fiber shaft and knob domains (Ad5/35) and compared its therapeutic efficacy with the homologous vector carrying the native Ad5 fiber. To further enhance virotherapy, we combined the oncolytic adenovirus vectors with intratumoral expression of measles virus fusogenic membrane glycoproteins H and F (MV-H/F) and dacarbazine chemotherapy. In a human melanoma xenograft model, established from a short-term culture of primary melanoma cells, we demonstrated that the Ad5/35-based therapy had a significantly greater anti-neoplastic effect than the homologous Ad5-based therapy. Furthermore, the combination of virotherapy, intratumoral expression of MV-H/F, and chemotherapy was clearly superior to single- or double-agent therapy. In conclusion, Ad35-based vectors are promising for the treatment of melanoma.

Comparison of herpes simplex virus- and conditionally replicative adenovirus-based vectors for glioblastoma treatment

In this study we compared side-by-side the anti-neoplastic activity of the oncolytic herpes simplex virus-1 (HSV-1) vector G47Delta with that of a conditionally replicative adenoviral vector for the treatment of glioblastoma. We analyzed the transduction efficiency of permanent glioblastoma cell lines and short-term cultures of glioblastoma cells with HSV.Luc and four adenovirus type 5 (Ad5)-based vectors that differed only in their fiber gene (Ad5.Luc, AdlucRGD, and the fiber chimeric vectors Ad5/3.Luc and Ad5/35.Luc). In the tested short-term cultures of glioblastoma cells the vectors Ad5/35.Luc and HSV.Luc had an equal transduction efficiency which was approximately 70% higher than that of Ad5.Luc. In a subcutaneous xenograft glioblastoma model in nude mice we observed a significantly higher local tumor control with the G47Delta vector compared to the conditionally replicative Ad5/35 adenovirus. We confirmed in glioblastoma that the intratumoral expression of measles virus fusogenic membrane glycoproteins (FMG) encoded by replication-defective Ad5/35 or HSV-1 amplicon vectors synergistically enhances chemotherapy with temozolomide. The anti-neoplastic effect was superior when the replication-defective FMG encoding vectors were trans-complemented for replication with the respective oncolytic vector. This approach was necessary due to packaging constraints of adenovirus. At day 100, of 6 treated animals 1 was alive that received the Ad5/35- and 3 that received the HSV-1-based triple therapy. In an intracranial glioblastoma xenograft model we demonstrated the applicability of this strategy. Due to the higher oncolytic efficacy and packaging capacity of the HSV-1 vectors compared to adenovirus, these vectors are promising for the treatment of glioblastoma.

Evaluation of twenty human adenoviral types and one infectivity-enhanced adenovirus for the therapy of soft tissue sarcoma

The clinical course of sarcoma warrants the development of new therapeutic options, such as gene therapy. However, the lack of coxsackievirus-adenovirus receptor (CAR) on sarcoma cells limits the efficacy of adenovirus type 5 (Ad5)-based gene therapy. In this study we evaluated 20 different adenoviral types and 1 Ad5 vector with RGD-containing fiber for their internalization efficiency in sarcoma cells. We demonstrated that adenovirus types 35, 3, 7, 11, 9, and 22 and Ad5lucRGD virions (ranked in descending order) have significantly higher internalization efficiency in the tested sarcoma cells when compared with Ad5. On the basis of these results we developed a conditionally replication-competent adenoviral vector, Ad5Delta24.Ki.COX, and compared its oncolytic efficacy with that of Ad5/35Delta24.Ki.COX, an Ad5-based vector with the Ad35 fiber shaft and knob domains. Because both vectors differed only in the fiber, we were able to assess whether the adenoviral type with the most efficient internalization resulted also in enhanced treatment efficacy. We evaluated the antineoplastic activity of the oncolytic adenoviral vectors alone or in combination with the expression of measles virus fusogenic membrane glycoproteins and/or ifosfamide. The findings of our xenograft model were as follows: animals that received Ad5/35-based therapy had significantly smaller tumors than animals treated with the homologous Ad5-based vectors. In addition, we demonstrated that the combination of virotherapy, intratumoral expression of fusogenic membrane glycoproteins, and ifosfamide was clearly superior compared with treatment with individual components alone or as combinations of two components. In conclusion, Ad35-based vectors are promising for the treatment of sarcoma.