Development of replication-competent adenovirus for bladder cancer by controlling adenovirus E1a and E4 gene expression with the survivin promoter

Tumor‐targeted fluorescence labeling systems for cancer diagnosis and treatment

Conventional imaging techniques are available for clinical identification of tumor sites. However, detecting metastatic tumor cells that are spreading from primary tumor sites using conventional imaging techniques remains difficult. In contrast, fluorescence‐based labeling systems are useful tools for detecting tumor cells at the single‐cell level in cancer research. The ability to detect fluorescent‐labeled tumor cells enables investigations of the biodistribution of tumor cells for the diagnosis and treatment of cancer. For example, the presence of fluorescent tumor cells in the peripheral blood of cancer patients is a predictive biomarker for early diagnosis of distant metastasis. The elimination of fluorescent tumor cells without damaging normal tissues is ideal for minimally invasive treatment of cancer. To capture fluorescent tumor cells within normal tissues, however, tumor‐specific activated target molecules are needed. This review focuses on recent advances in tumor‐targeted fluorescence labeling systems, in which indirect reporter labeling using tumor‐specific promoters is applied to fluorescence labeling of tumor cells for the diagnosis and treatment of cancer. Telomerase promoter‐dependent fluorescence labeling using replication‐competent viral vectors produces fluorescent proteins that can be used to detect and eliminate telomerase‐positive tumor cells. Tissue‐specific promoter‐dependent fluorescence labeling enables identification of specific tumor cells. Vimentin promoter‐dependent fluorescence labeling is a useful tool for identifying tumor cells that undergo epithelial–mesenchymal transition (EMT). The evaluation of tumor cells undergoing EMT is important for accurately assessing metastatic potential. Thus, tumor‐targeted fluorescence labeling systems represent novel platforms that enable the capture of tumor cells for the diagnosis and treatment of cancer.

Fiber-modified adenovirus-mediated suicide gene therapy can efficiently eliminate bladder cancer cells in vitro and in vivo

Adenovirus-mediated gene therapy is a promising strategy for bladder cancer treatment. However, the loss of the coxsackie and adenovirus receptor (CAR) in bladder cancer cells decreases the infection efficiency of the therapeutic adenovirus. In this study, we constructed an Arg-Gly-Asp (RGD)-modified adenovirus, RGDAd-UPII-TK, that carries a suicide gene called HSV-TK that is driven by a human UPII promoter. Then, we tested the bladder cancer specificity of the UPII promotor and the expression of the HSV-TK protein. Additionally, we observed a potent cytotoxic effects of RGDAd-UPII-TK and ganciclovir (GCV) on bladder cancer as demonstrated by reduced cell survival and morphology changes in vitro. Furthermore, we confirmed that RGDAd-UPII-TK in combination with a GCV injection could significantly reduce the established T24 tumor growth and increase apoptosis in vivo. Altogether, our results indicated that the recombinant adenovirus RGDAd-UPII-TK could target bladder cancer through valid gene therapy.

A classical PKA inhibitor increases the oncolytic effect of M1 virus via activation of exchange protein directly activated by cAMP 1

Oncolytic virotherapy is an emerging and promising treatment modality that uses replicating viruses as selective antitumor agents. Here, we report that a classical protein kinase A (PKA) inhibitor, H89, synergizes with oncolytic virus M1 in various cancer cells through activation of Epac1 (exchange protein directly activated by cAMP 1). H89 substantially increases viral replication in refractory cancer cells, leading to unresolvable Endoplasmic Reticulum stress, and cell apoptosis. Microarray analysis indicates that H89 blunts antiviral response in refractory cancer cells through retarding the nuclear translocation of NF-κB. Importantly, in vivo studies show significant antitumor effects during M1/H89 combination treatment. Overall, this study reveals a previously unappreciated role for H89 and demonstrates that activation of the Epac1 activity can improve the responsiveness of biotherapeutic agents for cancer.

Adenovirus-mediated downregulation of the ubiquitin ligase RNF8 sensitizes bladder cancer to radiotherapy

The ubiquitin ligase RNF8 promotes the DNA damage response (DDR). We observed that the expression of RNF8 was increased in bladder cancer cells and that this change in RNF8 expression could be reversed by adenovirus-mediated shRNA treatment. Moreover, we found that RNF8 knockdown sensitized bladder cancer cells to radiotherapy, as demonstrated by reduced cell survival. Additionally, the absence of RNF8 induced a high rate of apoptosis and impaired double-strand break repair signaling after radiotherapy. Furthermore, experiments on nude mice showed that combining shRNF8 treatment with radiotherapy suppressed implanted bladder tumor growth and enhanced apoptotic cell death in vivo. Altogether, our results indicated that RNF8 might be a novel target for bladder cancer treatment.

Cell-Surface Integrins and CAR Are Both Essential for Adenovirus Type 5 Transduction of Canine Cells of Lymphocytic Origin

Adenoviruses are the most widely used vectors in cancer gene therapy. Adenoviruses vectors are well characterized and are easily manipulated. Adenovirus serotype 5 (Ad5) is the most commonly used human serotype. Ad5 internalization into host cells is a combined effect of binding of Ad5 fiber knob with the coxsackie virus and adenovirus receptor (CAR) and binding of RGD motifs in viral penton to cell surface integrins (αvβ3, αvβ5). Ad5’s wide range of host-cell transduction and lack of integration into the host genome have made it an excellent choice for cancer therapeutics. However, Ad5 has limited ability to transduce cells of hematopoietic origin. It has been previously reported that low or no expression of CAR is a potential obstacle to Ad5 infection in hematopoietic origin cells. In addition, we have previously reported that low levels of cell surface integrins (αvβ3, αvβ5) may inhibit Ad5 infection in canine lymphoma cell lines. In the current report we have examined the ability of an Ad5 vector to infect human (HEK293) and canine non-cancerous (NCF and PBMC), canine non-hematopoietic origin cancer (CMT28, CML7, and CML10), and canine hematopoietic origin cancer (DH82, 17–71, OSW, MPT-1, and BR) cells. In addition, we have quantified CAR, αvβ3 and αvβ5 integrin transcript expression in these cells by using quantitative reverse transcriptase PCR (q-RT-PCR). Low levels of integrins were present in MPT1, 17–71, OSW, and PBMC cells in comparison to CMT28, DH82, and BR cells. CAR mRNA levels were comparatively higher in MPT1, 17–71, OSW, and PBMC cells. This report confirms and expands the finding that low or absent expression of cell surface integrins may be the primary reason for the inability of Ad5-based vectors to transduce cells of lymphocytic origin and some myeloid cells but this is not true for all hematopoietic origin cells. For efficient use of Ad5-based therapeutic vectors in cancers of lymphocytic origin, it is important to address the defects in cell surface integrins.

Trial Watch-Oncolytic viruses and cancer therapy

Oncolytic virotherapy relies on the administration of non-pathogenic viral strains that selectively infect and kill malignant cells while favoring the elicitation of a therapeutically relevant tumor-targeting immune response. During the past few years, great efforts have been dedicated to the development of oncolytic viruses with improved specificity and potency. Such an intense wave of investigation has culminated this year in the regulatory approval by the US Food and Drug Administration (FDA) of a genetically engineered oncolytic viral strain for use in melanoma patients. Here, we summarize recent preclinical and clinical advances in oncolytic virotherapy.

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.