Additional Gene Therapy with rAAV-wt-p53 Enhanced the Efficacy of Cisplatin in Human Bladder Cancer Cells

p53 gene delivery via a recombinant Salmonella enterica Typhimurium leads to human bladder carcinoma cell death in vitro

Numerous studies have attempted to restore the function of the tumour suppressor p53 as an anticancer strategy through gene delivery. However, most studies employed non-bacterial vectors to deliver p53. Various facultative and obligate anaerobic bacteria have been proposed as vectors because of their intrinsic tumour targeting ability and antitumour activity. Salmonella enterica Typhimurium is the most studied bacterial vector in anticancer therapy. We used the previously designed χ11218 strain of S. enterica Typhimurium, displaying regulated delayed lysis, as a vector for delivering p53 to human bladder carcinoma cells, restoring wild-type p53 protein function. We cloned p53 into pYA4545 (containing a eukaryotic expression system) to generate the χ11218 pYA4545p53 strain. Cloning of p53 did not affect the growth or interfere with the invasive and replicative capacity of χ11218 bacteria in tumour cells. Human bladder carcinoma cells (expressing mutated p53) transfected with pYA4545p53 showed a significant increase in the expression of p53 protein. We demonstrated that p53 supplied by χ11218 significantly decreased the viability of human bladder cancer cells in a dose-dependent manner. This study demonstrates the applicability of the attenuated χ11218 strain as a vector for DNA plasmids expressing tumour suppressor genes.

Enhancement of transduction efficiency using Adeno-associated viral vectors by chemical pretreatment to mice bladder urothelium

Adeno-associated virus (AAV) vectors have been recognized as promising tools for gene delivery. The bladder is a seemingly ideal organ for virus transfer, with easy access through the urethra enabling organ-specific delivery. However, achieving adequate transduction efficiency in the urothelium has been a major challenge because of the barrier function of the glycosaminoglycan (GAG) layer. We investigated optimal pretreatments of the bladder urothelium to maximize transduction efficiency by AAV vectors in vivo. Murine bladders were pretreated with five different chemical agents followed by transurethral instillation with an AAV2 vector encoding a tdTOMATO reporter. After 7 days, transduction efficiency of the urothelium was evaluated. Bladder urothelia pretreated with HCl showed clear evidence of AAV infection and gene delivery. Mice treated with 0.1 N HCl for 4 min showed significantly higher survival rates (nearly 80 %) compared with mice receiving other pretreatment regimens. AAV vector transduction in the urothelium was observed in seven of 20 mice (35 %), and the mean transduction efficiency in these mice was 14.5 %. Thus, HCl pretreatment enhanced transduction efficiency of the mice bladder urothelium by an AAV vector in vivo. Pretreatment with 0.1 N HCl for 4 min was the optimal condition to maximize survival and transduction efficiency of the urothelium.

Adeno-associated virus (AAV) vectors in cancer gene therapy

Gene delivery vectors based on adeno-associated virus (AAV) have been utilized in a large number of gene therapy clinical trials, which have demonstrated their strong safety profile and increasingly their therapeutic efficacy for treating monogenic diseases. For cancer applications, AAV vectors have been harnessed for delivery of an extensive repertoire of transgenes to preclinical models and, more recently, clinical trials involving certain cancers. This review describes the applications of AAV vectors to cancer models and presents developments in vector engineering and payload design aimed at tailoring AAV vectors for transduction and treatment of cancer cells. We also discuss the current status of AAV clinical development in oncology and future directions for AAV in this field.

An Efficient Light-Inducible P53 Expression System for Inhibiting Proliferation of Bladder Cancer Cell

Optogenetic gene expression systems enable spatial-temporal modulation of gene transcription and cell behavior. Although applications in biomedicine are emerging, the utility of optogenetic gene switches remains elusive in cancer research due to the relative low gene activation efficiency. Here, we present an optimized CRISPR-Cas9-based light-inducible gene expression device that controls gene transcription in a dose-dependent manner. To prove the potential utility of this device, P53 was tested as a functional target in the bladder cancer cell models. It was illustrated that the light-induced P53 inhibited proliferation of 5637 and UMUC-3 cell effectively. The "light-on" gene expression system may demonstrate a novel therapeutic strategy for bladder cancer intervention.

Synergistic anticancer effect of rAd/P53 combined with 5-fluorouracil or iodized oil in the early therapeutic response of human colon cancer in vivo

Exogenous wild-type p53 (wt-p53) tumor suppression increases the sensitivity of tumor cells to radiotherapy and chemotherapy. An iodized oil emulsion was used as a p53 vector for intra-arterial gene delivery to treat hepatic tumors. Whether the chemotherapeutic agent or the iodized oil affects exogenous wt-p53 activity remains poorly understood. In the present study, the early therapeutic response of rAd/p53, combined with 5-fluorouracil (5-FU) or with iodized oil, was observed in a human colon cancer model. Allograft models in 82 nude mice with human colon carcinoma SW480 were divided randomly into four groups and administered with physiologic saline, rAd/p53, rAd/p53+5-FU, and rAd/p53+iodized oil by intratumoral injection. At 24, 48, 72, 120, and 168 h after treatment, p53 expression, the Ki-67 index (KI), and the degree of tumor necrosis were assessed. The p53 expression and tumor necrosis in the therapeutic groups were higher than those in the control group. p53 expression reached its peak at 120 h in the rAd/p53 group, at 72 h in the rAd/p53+5-FU group, and at 48 h in the rAd/p53+iodized oil group. The p53 expression in the rAd/P53+5-FU group and the iodized oil group was significantly higher than those in the rAd/P53 group at 24 and 48 h. The results revealed that tumor necrosis is positively correlated with p53 expression. The KI of the rAd/p53+5-FU group increased significantly at 24 h. 5-FU and iodized oil increase the anticancer effect of rAd/p53, and 5-FU combined with rAd/p53 has a synergistic anticancer effect.

Combination of a fusogenic glycoprotein, pro-drug activation and oncolytic HSV as an intravesical therapy for superficial bladder cancer

Background:

There are still no effective treatments for superficial bladder cancer (SBC)/non-muscle invasive bladder cancer. Following treatment, 20% of patients still develop metastatic disease. Superficial bladder cancer is often multifocal, has high recurrences after surgical resection and recurs after intravesical live Bacillus Calmette–Guérin. Oncovex^GALV/CD, an oncolytic herpes simplex virus-1, has shown enhanced local tumour control by combining oncolysis with the expression of a highly potent pro-drug activating gene and the fusogenic glycoprotein.

Methods:

In vitro fusion/prodrug/apoptotic cell-based assays. In vivo orthotopic bladder tumour model, visualised by computed microtomography.

Results:

Treatment of seven human bladder carcinoma cell lines with the virus resulted in tumour cell killing through oncolysis, pro-drug activation and glycoprotein fusion. Oncovex^GALV/CD and mitomycin C showed a synergistic effect, whereas the co-administration with cisplatin or gemcitabine showed an antagonistic effect in vitro. Transitional cell cancer (TCC) cells follow an apoptotic cell death pathway after infection with Oncovex^GALV/CD with or without 5-FC. In vivo results showed that intravesical treatment with Oncovex^GALV/CD + prodrug (5-FC) reduced the average tumour volume by over 95% compared with controls.

Discussion:

Our in vitro and in vivo results indicate that Oncovex^GALV/CD can improve local tumour control within the bladder, and potentially alter its natural history.

RNA interference suppressing PLCE1 gene expression decreases invasive power of human bladder cancer T24 cell line

Mutational activation of the ras proto-oncogenes is frequently found in cancers. The phospholipase C epsilon gene (PLCE1) encodes a novel ras-related protein (R-Ras) effector mediating the effects of R-Ras on the actin cytoskeleton and membrane protrusion, because R-Ras is coprecipitated with the PLCE1 protein and can increase its activity. The nature of downstream signaling pathways from Ras involved in bladder cancer remains poorly understood. We aimed to construct a small hairpin RNA (shRNA) expression plasmid against the PLCE1 gene and to observe the inhibition of human bladder carcinoma cell T24 migration by RNA interference suppressing the expression of PLCE1. Two PLCE1 plasmids (P1 and P2) were constructed and inserted into T24 cells. Reverse transcriptase-polymerase chain reaction and Western blot analyses were performed to investigate inhibition of PLCE1 expression after plasmid transfection. Invasive power of the T24 cell line was measured before and after transfection by a membrane invasion culture system (transwell chamber), gelatin enzymography, and immunocytochemistry of cells. The RT-PCR analysis of BCL2 mRNA levels among different groups of T24 cell line indicated that expression of BCL2 mRNA was lower in the two positive plasmid-transfected cell groups than in the blank control or HK-A groups. Silencing of PLCE1 might downregulate the level of MMP and BCL2 gene expression, decreasing the invasive power of bladder cancer T24 cells and thus inhibiting tumor development.