Combination of bladder cancer-specific oncolytic adenovirus gene therapy with cisplatin on bladder cancer in vitro

Oncolytic Viruses for the Treatment of Bladder Cancer: Advances, Challenges, and Prospects

Bladder cancer is one of the most prevalent cancers. Despite recent advancements in bladder cancer therapy, new strategies are still required for improving patient outcomes, particularly for those who experienced Bacille Calmette-Guerin failure and those with locally advanced or metastatic bladder cancer. Oncolytic viruses are either naturally occurring or purposefully engineered viruses that have the ability to selectively infect and lyse tumor cells while avoiding harming healthy cells. In light of this, oncolytic viruses serve as a novel and promising immunotherapeutic strategy for bladder cancer. A wide diversity of viruses, including adenoviruses, herpes simplex virus, coxsackievirus, Newcastle disease virus, vesicular stomatitis virus, alphavirus, and vaccinia virus, have been studied in many preclinical and clinical studies for their potential as oncolytic agents for bladder cancer. This review aims to provide an overview of the advances in oncolytic viruses for the treatment of bladder cancer and highlights the challenges and research directions for the future.

Teratogenic Toxicity Evaluation of Bladder Cancer-Specific Oncolytic Adenovirus on Mice

BACKGROUND

In our previous studies, we had demonstrated the efficiency and specificity of constructed bladder tissue-specific adenovirus Ad-PSCAE-UPII-E1A-AR (APU-EIA-AR) on bladder cancer. The virus biodistribution and body toxicity in nude mice have also been investigated. However, the safety of the bladder cancer-specific oncolytic adenovirus on fetal mice and F1 mice should be under intense investigation.

OBJECTIVE

In order to evaluate the teratogenic toxicity of bladder cancer-specific oncolytic adenovirus APU-EIA-AR on mice, in this study, we investigated the fetal mice weight, fetal body length and tail length, fetal skeleton development, as well as the F1 mice weight, growth curve, and major organ pathology. These teratogenic toxicity data of bladder tissue-specific adenovirus Ad-PSCAE- UPII-E1A-AR (AD) would provide safe information prior to embarking on clinical trials.

METHODS

On the sixth day of being fertilized, the pregnant mice began to be intramuscularly administrated with AD (1×10⁷VP, 1×10⁸VP, 1×10⁹VP) every other day for ten days. The pregnant mice were then divided into two groups. One group was euthanized on the seventeenth day; the fetal mice were taken out, and the bone structure of the infants was observed. The other group was observed until natural childbirth. The Filial Generation (F1) is fed for 30 days; the variations in the growth progress and development were assessed. The mice were then euthanized; The tissues from major organs were harvested and observed under the microscope.

RESULTS

In the process of teratogenic toxicity test, the Placenta weight, fetal mice weight, body length, and a tail length of mice fetal in adenovirus treated group did not reveal any alteration. Meanwhile, comparing with the PBS group, there is no obvious change in the skeleton of fetal mice treated with adenovirus. During the development process of F1 mice treated with adenovirus, the changes in mice weight show statistical significance. However, in the progress of the growth curve, this difference is not very obvious. Furthermore, the pathological section showed no obvious alteration in major organs.

CONCLUSION

Our study demonstrated that bladder cancer-specific adenovirus Ad-PSCAE-UPII- E1A-AR appears safe in pregnant mice without any discernable effects on fetal mice and F1 development. Hence, it is relatively safe for tumor gene therapy.

Pushing the Right Buttons: Improving Efficacy of Therapeutic DNA Vectors

Gene therapy represents a potent therapeutical application for regenerative medicine. So far, viral and nonviral approaches suffer from major drawbacks hindering efficient gene therapeutic applicability: the immunogenicity of viral systems on the one hand, and the low gene transfer efficiency of nonviral systems on the other hand. Therefore, there is a high demand for improvements of therapeutical systems at several levels. This review summarizes different DNA vector modifications to enhance biological efficacy and efficiency of therapeutical vectors, aiming for low toxicity, high specificity, and biological efficacy-the cornerstones for successful translation of gene therapy into the clinic. We aim to provide a step-by-step instruction to optimize their vectors to achieve the desired outcome of gene therapy. Our review provides the means to either construct a potent gene therapeutic vector de novo or to specifically address a bottleneck in the chain of events mandatory for therapeutic success. Although most of the introduced techniques can be translated into different areas, this review primarily addresses improvements for applications in transient gene therapy in the field of tissue engineering.

A novel bladder cancer - specific oncolytic adenovirus by CD46 and its effect combined with cisplatin against cancer cells of CAR negative expression

BACKGROUND

Conditionally replicative oncolytic adenoviruses (CRAds) display significant anti-tumor effects. However, the traditional adenovirus of serotype 5 (Ad5) entering cancer cells via coxsackie virus and adenovirus receptor (CAR) can't be utilized for bladder cancer with low expression of CAR, which limits the application of Ad5.

METHODS

We utilized Ad5/F11p containing the chimeric fiber gene encoding the Ad5 fiber tail domain and Ad11p fiber shaft and knob domains to construct bladder cancer-specific chimeric type viruses Ad5/F11p-PSCAE-UPII-E1A, which can infect bladder cancer cells mediated by CD46 molecule. We carried out series of experiments in vitro to research anti-tumor effect of Ad5/F11p-PSCAE-UPII-E1A and the interaction in combination with cisplatin.

RESULTS

The results demonstrated Ad5/F11p-PSCAE-UPII-E1A could infect bladder cancer cells (T24, EJ and 5637) in a CAR-independent way, and exert anti-tumor effect by blocking the cancer cells in G1 phase and inducing apoptosis. Ad5/F11p-PSCAE-UPII-E1A plus cisplatin enhanced the anti-proliferative effect and increased the number of apoptotic cells compared with viruses or cisplatin alone. Ad5/F11p-PSCAE-UPII-E1A plus cisplatin could upregulate the proteins expression of p53, Bax, and cleaved caspase-3, and downregulated Bcl-2 protein expression in T24, EJ and 5637 cells.

CONCLUSION

We constructed a bladder cancer-specific oncolytic adenovirus and provided new combination treatment strategies for bladder cancer.

Progresses towards safe and efficient gene therapy vectors

The emergence of genetic engineering at the beginning of the 1970′s opened the era of biomedical technologies, which aims to improve human health using genetic manipulation techniques in a clinical context. Gene therapy represents an innovating and appealing strategy for treatment of human diseases, which utilizes vehicles or vectors for delivering therapeutic genes into the patients' body. However, a few past unsuccessful events that negatively marked the beginning of gene therapy resulted in the need for further studies regarding the design and biology of gene therapy vectors, so that this innovating treatment approach can successfully move from bench to bedside. In this paper, we review the major gene delivery vectors and recent improvements made in their design meant to overcome the issues that commonly arise with the use of gene therapy vectors. At the end of the manuscript, we summarized the main advantages and disadvantages of common gene therapy vectors and we discuss possible future directions for potential therapeutic vectors.

xCT expression modulates cisplatin resistance in Tca8113 tongue carcinoma cells

Tongue squamous cell carcinoma (TSCC), which is a subtype of head and neck cancer, is the most common type of oral cancer. Due to its high recurrence rate and chemoresistance, the average survival rate for patients with TSCC remains unsatisfactory. At present, cisplatin (CDDP) is utilized as the first-line treatment for numerous solid neoplasms, including TSCC. CDDP resistance develops in the majority of patients; however, the mechanism of such resistance remains unknown. Therefore, the present study aimed to clarify the mechanism of CDDP resistance and attempted to reduce chemoresistance. The results indicated that CDDP significantly increased expression of xCT, which is the light chain and functional subunit of the glutamate/cysteine transporter system x_c^-, and a subsequent increase in glutathione (GSH) levels was observed. The present study demonstrated that the upregulation of xCT expression and intercellular GSH levels contributed to CDDP resistance in TSCC cells. Furthermore, xCT suppression, induced by small interfering RNA or pharmacological inhibitors, sensitized TSCC cells to CDDP treatment. In conclusion, the present study revealed that CDDP-induced xCT expression promotes CDDP chemoresistance, and xCT inhibition sensitizes TSCC cells to CDDP treatment. These results provide a novel insight into the molecular mechanisms involved in TSCC cell chemoresistance.

Gene therapy targeting hepatocellular carcinoma by a dual-regulated oncolytic adenovirus harboring the focal adhesion kinase shRNA

Cancer targeting gene-viro-therapy (CTGVT) approach has become a hotspot and a trend in the field of cancer biotherapy and oncolytic adenovirus is an ideal vector to carry the targeting genes. In this study, we used human telomerase reverse transcriptase (hTERT) promoter to control the adenovirus early region 1a (E1A) and the human α-fetoprotein (AFP) promoter integrated with hypoxia response element (HRE) to control the adenovirus early region 1b (E1B). Then the novel double-regulated adenovirus Ad-hTERT-HREAF (named SG505) was engineered. The short-hairpin RNA against focal adhesion kinase (FAK) was inserted into SG505 and thus forming Ad-hTERT-HREAF-shRNA (called SG505‑siFAK). Then various oncolytic adenoviruses were examined to verify whether they could suppress liver cancer cells selectively and efficiently both in vitro and in vivo. Both replicative and replication-defective adenoviruses carrying FAK-shRNA significantly inhibited the expression of FAK in Hep3B and SMMC-7721 cell lines and efficiently suppressed the growth of liver cancer cell lines with minor effect to normal cells. Furthermore, the recombined oncolytic adenoviruses, SG505-siFAK, SG505-EGFP and SG505 were able to selectively propagate in AFP-positive liver cancer cells in vitro and the SG505-siFAK efficiently suppressed the expression of FAK. SG505-siFAK showed the most potent tumor inhibition capability among the three recombined adenovirus with IC50 levels of 0.092±0.009 and 0.424±0.414 pfu/cell in the Hep3B and HepG2 cell line, respectively. Animal experiment further confirmed that SG505-siFAK achieved the most significant tumor inhibition of Hep3B liver cancer xenografted growth by intratumoral injection comparing to the intravenous injection among the three recombined viruses. Immunohistochemical results indicated that FAK expression was downregulated significantly in the tumors treated with SG505-siFAK. The dual-regulated oncolytic adenovirus SG505-siFAK was proven to inhibit the growth of liver cancer cells selectively and efficiently, therefore SG505-siFAK could be a potential agent for future clinical trials of hepatocellular carcinoma.

RGD-modifided oncolytic adenovirus exhibited potent cytotoxic effect on CAR-negative bladder cancer-initiating cells

Cancer-initiating cell (CIC) is critical in cancer development, maintenance and recurrence. The reverse expression pattern of coxsackie and adenovirus receptor (CAR) and α_ν integrin in bladder cancer decreases the infection efficiency of adenovirus. We constructed Arg-Gly-Asp (RGD)-modified oncolytic adenovirus, carrying EGFP or TNF-related apoptosis-inducing ligand (TRAIL) gene (Onco^Ad.RGD-hTERT-EGFP/TRAIL), and applied them to CAR-negative bladder cancer T24 cells and cancer-initiating T24 sphere cells. Onco^Ad.RGD-hTERT-EGFP had enhanced infection ability and cytotoxic effect on T24 cells and T24 sphere cells, but little cytoxicity on normal urothelial SV-HUC-1 cells compared with the unmodified virus Onco^Ad.hTERT-EGFP. Notably, Onco^Ad.RGD-hTERT-TRAIL induced apoptosis in T24 cells and T24 sphere cells. Furthermore, it completely inhibited xenograft initiation established by the oncolytic adenovirus-pretreated T24 sphere cells, and significantly suppressed tumor growth by intratumoral injection. These results provided a promising therapeutic strategy for CAR-negative bladder cancer through targeting CICs.