Enhanced antitumor efficacy of a novel fiber chimeric oncolytic adenovirus expressing p53 on hepatocellular carcinoma

Advancements in p53-Based Anti-Tumor Gene Therapy Research

The p53 gene is one of the genes most closely associated with human tumors and has become a popular target for tumor drug design. Currently, p53-based gene therapy techniques have been developed, but these therapies face challenges such as immaturity, high safety hazards, limited efficacy, and low patient acceptance. However, researchers are no less enthusiastic about the treatment because of its theoretical potential to treat cancer. In this paper, the advances in p53-based gene therapy and related nucleic acid delivery technologies were reviewed and prospected in order to support further development in this field.

Role of homologous recombination/recombineering on human adenovirus genome engineering: Not the only but the most competent solution

Adenoviruses typically cause mild illnesses, but severe diseases may occur primarily in immunodeficient individuals, particularly children. Recently, adenoviruses have garnered significant interest as a versatile tool in gene therapy, tumor treatment, and vaccine vector development. Over the past two decades, the advent of recombineering, a method based on homologous recombination, has notably enhanced the utility of adenoviral vectors in therapeutic applications. This review summarizes recent advancements in the use of human adenoviral vectors in medicine and discusses the pivotal role of recombineering in the development of these vectors. Additionally, it highlights the current achievements and potential future impact of therapeutic adenoviral vectors.

Complement Regulatory Protein CD46 Manifests a Unique Role in Promoting the Migration of Bladder Cancer Cells

CD46 is a membrane-bound complement regulatory protein (mCRP) possessing a regulatory role with the complement system. CD46 protects the host cells from damage by complement. Expression of CD46 is also highly maintained in many cancers, including bladder cancers, and thus functions as a receptor for many cancer therapeutic viruses. In this study we report a unique role of CD46 as a progression factor of cancer cells in bladder cancers. Resulting data from a DNA microarray using CD46-altered HT1376 bladder cancers demonstrated a pool of target genes, including complement C3 α chain (C3α), matrix Gla protein (MGP), AFAP-AS1, follicular dendritic cell secreted protein (FDCSP), MAM domain containing 2 (MAMDC2), gamma-aminobutyric acid A receptor pi (GABRP), transforming growth factor, beta-induced (TGFBI), a family of cytochrome P450 (CYP24A1), sialic acid binding Ig-like lectin 6 (SIGLEC6), metallothionein 1E (MT1E), and several members of cytokeratins. Subsequent studies using quantitative RT-PCR and Western blot analyses confirmed CD46-mediated regulation of C3α, MGP, and keratin 13 (KRT13). MGP and KRT13 are known to be involved in cell migration and cancer cell metastasis. A cell migration assay demonstrated that CD46 enhanced migratory potential of bladder cancer cells. Taken all together, this report demonstrated that CD46 is generally overexpressed in bladder cancers and plays a unique role in the promotion of cancer cell migration. Further detailed studies are needed to be performed to clarify the action mechanism of CD46 and its application to cancer therapeutics.

Modern approaches to treating cancer with oncolytic viruses

According to the World Health Organization, cancer is the second leading cause of death in the world. This serves as a powerful incentive to search for new effective cancer treatments. Development of new oncolytic viruses capable of selectively destroying cancer cells is one of the modern approaches to cancer treatment. The advantage of this method – the selective lysis of tumor cells with the help of viruses – leads to an increase in the antitumor immune response of the body, that in turn promotes the destruction of the primary tumor and its metastases. Significant progress in development of this method has been achieved in the last decade. In this review we analyze the literature data on families of oncolytic viruses that have demonstrated a positive therapeutic effect against malignant neoplasms in various localizations. We discuss the main mechanisms of the oncolytic action of viruses and assess their advantages over other methods of cancer therapy as well as the prospects for their use in clinical practice.

In Vivo Oncolytic Virotherapy in Murine Models of Hepatocellular Carcinoma: A Systematic Review

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related mortality worldwide. Current therapies often provide marginal survival benefits at the expense of undesirable side effects. Oncolytic viruses represent a novel strategy for the treatment of HCC due to their inherent ability to cause direct tumor cell lysis while sparing normal tissue and their capacity to stimulate potent immune responses directed against uninfected tumor cells and distant metastases. Oncolytic virotherapy (OVT) is a promising cancer treatment, but before it can become a standard option in practice, several challenges-systemic viral delivery optimization/enhancement, inter-tumoral virus dispersion, anti-cancer immunity cross-priming, and lack of artificial model systems-need to be addressed. Addressing these will require an in vivo model that accurately mimics the tumor microenvironment and allows the scientific community to design a more precise and accurate OVT. Due to their close physiologic resemblance to humans, murine cancer models are the likely preferred candidates. To provide an accurate assessment of the current state of in vivo OVT in HCC, we have reviewed a comprehensively searched body of work using murine in vivo HCC models for OVT.

Oncolytic Adenovirus: Prospects for Cancer Immunotherapy

Immunotherapy has moved to the forefront of modern oncologic treatment in the past few decades. Various forms of immunotherapy currently are emerging, including oncolytic viruses. In this therapy, viruses are engineered to selectively propagate in tumor cells and reduce toxicity for non-neoplastic tissues. Adenovirus is one of the most frequently employed oncolytic viruses because of its capacity in tumor cell lysis and immune response stimulation. Upregulation of immunostimulatory signals induced by oncolytic adenoviruses (OAds) might significantly remove local immune suppression and amplify antitumor immune responses. Existing genetic engineering technology allows us to design OAds with increasingly better tumor tropism, selectivity, and antitumor efficacy. Several promising strategies to modify the genome of OAds have been applied: capsid modifications, small deletions in the pivotal viral genes, insertion of tumor-specific promoters, and addition of immunostimulatory transgenes. OAds armed with tumor-associated antigen (TAA) transgenes as cancer vaccines provide additional therapeutic strategies to trigger tumor-specific immunity. Furthermore, the combination of OAds and immune checkpoint inhibitors (ICIs) increases clinical benefit as evidence shown in completed and ongoing clinical trials, especially in the combination of OAds with antiprogrammed death 1/programed death ligand 1 (PD-1/PD-L1) therapy. Despite remarkable antitumor potency, oncolytic adenovirus immunotherapy is confronted with tough challenges such as antiviral immune response and obstruction of tumor microenvironment (TME). In this review, we focus on genomic modification strategies of oncolytic adenoviruses and applications of OAds in cancer immunotherapy.

"Complimenting the Complement": Mechanistic Insights and Opportunities for Therapeutics in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver and a leading cause of death in the US and worldwide. HCC remains a global health problem and is highly aggressive with unfavorable prognosis. Even with surgical interventions and newer medical treatment regimens, patients with HCC have poor survival rates. These limited therapeutic strategies and mechanistic understandings of HCC immunopathogenesis urgently warrant non-palliative treatment measures. Irrespective of the multitude etiologies, the liver microenvironment in HCC is intricately associated with chronic necroinflammation, progressive fibrosis, and cirrhosis as precedent events along with dysregulated innate and adaptive immune responses. Central to these immunological networks is the complement cascade (CC), a fundamental defense system inherent to the liver which tightly regulates humoral and cellular responses to noxious stimuli. Importantly, the liver is the primary source for biosynthesis of >80% of complement components and expresses a variety of complement receptors. Recent studies implicate the complement system in liver inflammation, abnormal regenerative responses, fibrosis, carcinogenesis, and development of HCC. Although complement activation differentially promotes immunosuppressive, stimulant, and angiogenic microenvironments conducive to HCC development, it remains under-investigated. Here, we review derangement of specific complement proteins in HCC in the context of altered complement regulatory factors, immune-activating components, and their implications in disease pathogenesis. We also summarize how complement molecules regulate cancer stem cells (CSCs), interact with complement-coagulation cascades, and provide therapeutic opportunities for targeted intervention in HCC.

A novel oncolytic adenovirus inhibits hepatocellular carcinoma growth

OBJECTIVE

To evaluate the inhibitory role of a novel oncolytic adenovirus (OA), GP73-SphK1sR-Ad5, on the growth of hepatocellular carcinoma (HCC).

METHODS

GP73-SphK1sR-Ad5 was constructed by integrating Golgi protein 73 (GP73) promoter and sphingosine kinase 1 (SphK1)-short hairpin RNA (shRNA) into adenovirus serotype 5 (Ad5), and transfecting into HCC Huh7 cells and normal human liver HL-7702 cells. The expression of SphK1 and adenovirus early region 1 (E1A) was detected by quantitative real-time PCR (qRT-PCR) and western blot, respectively. Cell viability was detected by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay, and apoptotic rate was determined by flow cytometry. An Huh7 xenograft model was established in mice injected intratumorally with GP73-SphK1sR-Ad5. Twenty days after injection, the tumor volume and weight, and the survival time of the mice were recorded. The histopathological changes in tumor tissues were observed by hematoxylin-eosin (HE) staining and transmission electron microscopy (TEM).

RESULTS

Transfection of GP73-SphK1sR-Ad5 significantly upregulated E1A and downregulated SphK1 in Huh7 cells, but not in HL7702 cells. GP73-SphK1sR-Ad5 transfection significantly decreased the viability and increased the apoptotic rate of Huh7 cells, but had no effect on HL7702 cells. Intratumoral injection of GP73-SphK1sR-Ad5 into the Huh7 xenograft mouse model significantly decreased tumor volume and weight, and prolonged survival time. It also significantly decreased the tumor infiltration area and blood vessel density, and increased the percentages of cells with nucleus deformation and cells with condensed chromatin in tumor tissues.

CONCLUSIONS

GP73-SphK1sR-Ad5 serves as a novel OA and can inhibit HCC progression with high specificity and efficacy.

Fighting Cancer with Viruses: Oncolytic Virus Therapy in China

As part of oncolytic virotherapy to treat cancer, oncolytic viruses (OVs) can selectively infect tumor cells to promote oncolysis of cancer cells, local immunological reactions, and systemic antitumor immunity with minimal toxicity to normal tissues. The immunostimulatory properties of OVs provide enormous benefits for the treatment of cancer. A variety of OVs, including genetically engineered and natural viruses, have shown promise in preclinical models and clinical studies. In 2005, the China Food and Drug Administration approved its first OV drug, Oncorine (H101), for treatment of advanced head and neck cancer. To explore new treatment strategies, >200 recombinant or natural OVs are undergoing in-depth investigation in China, and >250 oncolytic virotherapy-related reports from the OV community in China have been published in the past 5 years. These studies investigated a variety of exogenous genes and combination therapeutic strategies to enhance the treatment effects of OVs. To date, five clinical trials covering four OV agents (Oncorine, OrienX010, KH901, and H103) are ongoing, and additional OV agents are awaiting approval for clinical trials in China. Overall, this research emphasizes that combination therapy, especially tumor immunotherapy coupled with effective system administration strategies, can promote the development of oncolytic virotherapies. This article focuses on studies that were carried out in China in order to give an overview of the past, present, and future of oncolytic virotherapy in China.

Efficacy of CD46-targeting chimeric Ad5/35 adenoviral gene therapy for colorectal cancers

CD46 is a complement inhibitor membrane cofactor which also acts as a receptor for various microbes, including species B adenoviruses (Ads). While most Ad gene therapy vectors are derived from species C and infect cells through coxsackie-adenovirus receptor (CAR), CAR expression is downregulated in many cancer cells, resulting inefficient Ad-based therapeutics. Despite a limited knowledge on the expression status of many cancer cells, an increasing number of cancer gene therapy studies include fiber-modified Ad vectors redirected to the more ubiquitously expressed CD46. Since our finding from tumor microarray indicate that CD46 was overexpressed in cancers of the prostate and colon, fiber chimeric Ad5/35 vectors that have infection tropism for CD46 were employed to demonstrate its efficacy in colorectal cancers (CRC). CD46-overexpressed cells showed a significantly higher response to Ad5/35-GFP and to Ad5/35-tk/GCV. While CRC cells express variable levels of CD46, CD46 expression was positively correlated with Ad5/35-mediated GFP fluorescence and accordingly its cell killing. Injection of Ad5/35-tk/GCV caused much greater tumor-suppression in mice bearing CD46-overexpressed cancer xenograft compared to mock group. Analysis of CRC samples revealed that patients with positive CD46 expression had a higher survival rate (p=0.031), carried tumors that were well-differentiated, but less invasive and metastatic, and with a low T stage (all p<0.05). Taken together, our study demonstrated that species B-based adenoviral gene therapy is a suitable approach for generally CD46-overexpressed CRC but would require careful consideration preceding CD46 analysis and categorizing CRC patients.

A novel fiber chimeric conditionally replicative adenovirus-Ad5/F35 for tumor therapy

Significant progress has been made in the diagnosis and treatment of cancer; however, significant challenges remain. Conditionally replicating adenoviruses (CRAds), which not only kill cancer cells, but also serve as vectors to express therapeutic genes, are a novel and effective method to treat cancer. However, most adenoviruses are Ad5, which infect cells through the coxsackie and adenovirus receptor (CAR). The transduction efficacy of Ad5 is restricted because of the absent or low expression of CAR on several cancer cells. Ad serotype 35 has a different tropism pattern to Ad5. Ad35 attaches to cells via a non-CAR receptor, CD46, which is expressed widely on most tumor cells. Thus, chimeric adenoviral vectors consisting of the knob and shaft of Ad35 combined with Ad5 have been constructed. The chimeric fiber adenoviral vectors can transduce CAR-positive and CAR-negative cell lines. In this review, we explore the application of the novel fiber chimeric conditionally replicative adenovirus-Ad5/F35 in tumor therapy in terms of safety, mechanism, transduction efficacy, and antitumor effect.

Cytotoxicity of replication-competent adenoviruses powered by an exogenous regulatory region is not linearly correlated with the viral infectivity/gene expression or with the E1A-activating ability but is associated with the p53 genotypes

Background

Replication-competent adenoviruses (Ad) produced cytotoxic effects on infected tumors and have been examined for the clinical applicability. A biomarkers to predict the cytotoxicity is valuable in a clinical setting.

Methods

We constructed type 5 Ad (Ad5) of which the expression of E1A gene was activated by a 5′ regulatory sequences of survivin, midkine or cyclooxygenase-2, which were highly expressed in human tumors. We also produced the same replication-competent Ad of which the fiber-knob region was replaced by that of Ad35 (AdF35). The cytotoxicity was examined by a colorimetric assay with human tumor cell lines, 4 kinds of pancreatic, 9 esophageal carcinoma and 5 mesothelioma. Ad infectivity and Ad-mediated gene expression were examined with replication-incompetent Ad5 and AdF35 which expressed the green fluorescence protein gene. Expression of cellular receptors for Ad5 and AdF35 was also examined with flow cytometry. A transcriptional activity of the regulatory sequences was investigated with a luciferase assay in the tumor cells. We then investigated a possible correlation between Ad-mediated cytotoxicity and the infectivity/gene expression, the transcriptional activity or the p53 genotype.

Results

We found that the cytotoxicity was greater with AdF35 than with Ad5 vectors, but was not correlated with the Ad infectivity/gene expression irrespective of the fiber-knob region or the E1A-activating transcriptional activity. In contrast, replication-competent Ad produced greater cytotoxicity in p53 mutated than in wild-type esophageal carcinoma cells, suggesting a possible association between the cytotoxicity and the p53 genotype.

Conclusions

Sensitivity to Ad-mediated cytotoxic activity was linked with the p53 genotype but was not lineally correlated with the infectivity/gene expression or the E1A expression.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3621-x) contains supplementary material, which is available to authorized users.

Gene Variations of Sixth Complement Component Affecting Tacrolimus Metabolism in Patients with Liver Transplantation for Hepatocellular Carcinoma

BACKGROUND

Orthotopic liver transplantation (OLT) improves the prognosis of patients with hepatocellular carcinoma (HCC). Moreover, the complement system is a powerful immune effector that can affect liver function and process of liver cirrhosis. However, studies correlating the complement system with tacrolimus metabolism after OLT are scarce. In this study, the role of single nucleotide polymorphisms (SNPs) associated with the sixth complement component (C6) in tacrolimus metabolism was investigated during the early stages of liver transplantation.

METHODS

The study enrolled 135 adult patients treated with OLT for HCC between August 2011 and October 2013. Ten SNPs in C6 gene and rs776746 in cytochrome P450 3A5 (CYP3A5) gene were investigated. The tacrolimus levels were monitored daily during 4 weeks after transplantation.

RESULTS

Both donor and recipient CYP3A5 rs776746 allele A were correlated with decreased concentration/dose (C/D) ratios. Recipient C6 rs9200 allele G and donor C6 rs10052999 homozygotes were correlated with lower C/D ratios. Recipient CYP3A5 rs776746 allele A (yielded median tacrolimus C/D ratios of 225.90 at week 1 and 123.61 at week 2), C6 rs9200 allele G (exhibited median tacrolimus C/D ratios of 211.31 at week 1, 110.23 at week 2, and 99.88 at week 3), and donor CYP3A5 rs776746 allele A (exhibited median C/D ratios of 210.82 at week 1, 111.06 at week 2, 77.49 at week 3, and 85.60 at week 4) and C6 rs10052999 homozygote (exhibited median C/D ratios of 167.59 at week 2, 157.99 at week 3, and 155.36 at week 4) were associated with rapid tacrolimus metabolism. With increasing number of these alleles, patients were found to have lower tacrolimus C/D ratios at various time points during the 4 weeks after transplantation. In multiple linear regression analysis, recipient C6 rs9200 group (AA vs. GG/GA) was found to be related to tacrolimus metabolism at weeks 1, 2, and 3 (P = 0.005, P = 0.045, and P = 0.033, respectively), whereas donor C6 rs10052999 group (CC/TT vs. TC) was demonstrated to be correlated with tacrolimus metabolism only at week 4 (P = 0.001).

CONCLUSIONS

Recipient C6 gene rs9200 polymorphism and donor C6 gene rs10052999 polymorphism are new genetic loci that affect tacrolimus metabolism in patients with HCC after OLT.

Oncolytic virotherapy for urological cancers

Oncolytic virotherapy is a cancer treatment in which replication-competent viruses are used that specifically infect, replicate in and lyse malignant tumour cells, while minimizing harm to normal cells. Anecdotal evidence of the effectiveness of this strategy has existed since the late nineteenth century, but advances and innovations in biotechnological methods in the 1980s and 1990s led to a renewed interest in this type of therapy. Multiple clinical trials investigating the use of agents constructed from a wide range of viruses have since been performed, and several of these enrolled patients with urological malignancies. Data from these clinical trials and from preclinical studies revealed a number of challenges to the effectiveness of oncolytic virotherapy that have prompted the development of further sophisticated strategies. Urological cancers have a range of distinctive features, such as specific genetic mutations and cell surface markers, which enable improving both effectiveness and safety of oncolytic virus treatments. The strategies employed in creating advanced oncolytic agents include alteration of the virus tropism, regulating transcription and translation of viral genes, combination with chemotherapy, radiotherapy or gene therapy, arming viruses with factors that stimulate the immune response against tumour cells and delivery technologies to ensure that the viral agent reaches its target tissue.

Selective effects of a fiber chimeric conditionally replicative adenovirus armed with hep27 gene on renal cancer cell

ASBTARCT Adenoviruses mediated cancer gene therapies are widely investigated and show a promising effect on cancer treatment. However, efficient gene transfer varies among different cancer cell lines based on the expression of coxsakie adenovirus receptor (CAR). Hep27, a member of dehydrogenase/reductase (SDR) family, can bind to Mdm2, resulting in the attenuation of Mdm2-mediated p53 degradation. Here we constructed a fiber chimeric adenovirus carrying hep27 gene (F5/35-ZD55-Hep27), in which the fiber protein of 5-serotype adenovirus (Ad5) was substituted by that of 35-serotype adenovirus (Ad35), aiming to facilitate the infection for renal cancer cells and develop the role of hep27 in cancer therapy. We evaluated the CAR and CD46 (a membrane cofactor protein for Ad35) expression in four kinds of renal cancer cells and assessed the relationship between receptors and infection efficiency. 5/35 fiber-modified adenovirus had a much promising infectivity compared with Ad5-based vector in renal cancer cells. F5/35-ZD55-Hep27 had enhanced antitumor activity against human renal cancer cells compared to the other groups. Further, hep27 mediated p53 and cleaved-PARP upregulation and mdm2 downregulation was involved and caused increased apoptosis. Moreover, F5/35-ZD55-Hep27 significantly suppressed tumor growth in subcutaneous renal cancer cell xenograft models. Our data demonstrated that 5/35 fiber-modified adenovirus F5/35-ZD55-Hep27 transferred into renal cancers efficiently and increased p53 to induce cancer cell apoptosis. Thus 5/35 fiber-modified adenoviral vector F5/35-ZD55-Hep27 might a promising vector and antitumor reagent for renal cancer gene therapy.

Long-term toxicity study of rAd5-hTERTC27 in SD rats and Cynomolgus monkeys by intravenous injection

rAd5-hTERTC27, a replication-defective adenovirus vector carrying hTERTC27, has been proposed for possible use against hepatocellular carcinoma (HCC). In this study, we investigated the long-term toxicity of rAd5-hTERTC27 in SD rats and Cynomolgus monkeys. rAd5-hTERTC27 was administered intravenously once a week for 13 weeks followed by a one-month recovery period. As of 4 months, all animals displayed overall good health. Anti-adenoviral antibodies emerged in a dose-independent manner. The levels of complement components, C3 and C4, in the rAd5-hTERTC27 middle-dose and high-dose groups and C4 in the rAd5-EGFP group increased significantly after the 2nd treatment in monkeys. Slight-mild pathological changes of the liver occurred only in the rAd5-hTERTC27 high-dose group (2/16) in rats and not in any other group in either rats or monkeys. With the increase of the dose, the incidence of lymphocyte depletion in the spleen of rats and reactive hyperplasia of the splenic corpuscle in monkeys increased. However, the changes in the liver and spleen were reversible. Given the above data, intravenous administration of rAd5-hTERTC27 (up to 4×10(10)VP/kg in rats and 0.9×10(10)VP/kg in monkeys) appears to be well-tolerated, providing support for its potentially safe use in clinical trials for the treatment of HCC.

Sigma 1 Receptor antagonist potentiates the anti-cancer effect of p53 by regulating ER stress, ROS production, Bax levels, and caspase-3 activation

Over the last years, many improvements have been made in the treatment of breast cancer; however, novel and less toxic therapies are still needed, especially for relapsing and chemo-resistant patients. Here, we analyzed the therapeutic potential of p53 and Rimcazole, a Sigma 1 Receptor antagonist. Rimcazole and p53 are being evaluated in preclinical and clinical trials, respectively. While p53 is a promising antitumor therapeutic agent, antagonists of Sigma 1 Receptor also inhibit tumor cell survival and induce apoptosis. Our current study demonstrates for the first time the synergistic effect of p53 in combination with the Sigma 1 Receptor antagonist Rimcazole. Furthermore, we show that shRNA knockdown of Sigma 1 Receptor in combination with p53, lead to a similar synergistic effect, and that this synergistic effect, in breast cancer growth suppression occurs independent of p53 status. Furthermore, this combination treatment induced ER stress, p38 MAPK activation, ROS production, and proteins involved in apoptosis (caspases-3, Bax) in breast cancer cells. Combining these therapeutic anti-cancer molecules provides an innovative approach for potentially treating human breast cancer.

Clinical utility of recombinant adenoviral human p53 gene therapy: current perspectives

Gene therapy has promised to be a highly effective antitumor treatment by introducing a tumor suppressor gene or the abrogation of an oncogene. Among the potential therapeutic transgenes, the tumor suppressor gene p53 serves as an attractive target. Restoration of wild-type p53 function in tumors can be achieved by introduction of an intact complementary deoxyribonucleic acid copy of the p53 gene using a suitable viral vector, in most cases an adenoviral vector (Adp53). Preclinical in vitro and in vivo studies have shown that Adp53 triggers a dramatic tumor regression response in various cancers. These viruses are engineered to lack certain early proteins and are thus replication defective, including Gendicine, SCH-58500, and Advexin. Several types of tumor-specific p53-expressing conditionally replicating adenovirus vectors (known as replication-competent CRAdp53 vectors) have been developed, such as ONYX 015, AdDelta24-p53, SG600-p53, OBP-702, and H101. Various clinical trials have been conducted to investigate the safety and efficiency of these adenoviral vectors. In this review we will talk about the biological mechanisms, clinical utility, and therapeutic potentials of the replication-deficient Adp53-based and replication-competent CRAdp53-based gene therapy.

Anti-tumor activity of a miR-199-dependent oncolytic adenovirus

The down-regulation of miR-199 occurs in nearly all primary hepatocellular carcinomas (HCCs) and HCC cell lines in comparison with normal liver. We exploited this miR-199 differential expression to develop a conditionally replication-competent oncolytic adenovirus, Ad-199T, and achieve tumor-specific viral expression and replication. To this aim, we introduced four copies of miR-199 target sites within the 3’ UTR of E1A gene, essential for viral replication. As consequence, E1A expression from Ad-199T virus was tightly regulated both at RNA and protein levels in HCC derived cell lines, and replication controlled by the level of miR-199 expression. Various approaches were used to asses in vivo properties of Ad-199T. Ad-199T replication was inhibited in normal, miR-199 positive, liver parenchyma, thus resulting in reduced hepatotoxicity. Conversely, the intrahepatic delivery of Ad-199T in newborn mice led to virus replication and fast removal of implanted HepG2 liver cancer cells. The ability of Ad-199T to control tumor growth was also shown in a subcutaneous xenograft model in nude mice and in HCCs arising in immune-competent mice. In summary, we developed a novel oncolytic adenovirus, Ad-199T, which could demonstrate a therapeutic potential against liver cancer without causing significant hepatotoxicity.

Preclinical safety evaluation of rAd5-hTERTC27 by intravenous injection

The safety of rAd5-hTERTC27, a replication defective adenovirus vector carrying hTERTC27 for possible use against hepatocellular carcinoma (HCC) was assessed. In single-dose evaluations, intravenous dose levels of up to 2×10(11)VP/kg in rats and 9×10(10)VP/kg in monkeys were well tolerated with no abnormal changes in general signs, body weight and food consumption, and no significant differences in biochemical parameters, urinalysis, ECG, and systemic necropsy observations between the rAd5 groups and solvent control group except that slight hematological change was observed. No hemolytic effect using rabbit blood, local perivasculitis following intravenous injection in rabbits or systemic anaphylaxis in guinea pigs following intravenous dosing was seen. No effects on the central nervous system of mice occurred following intravenous dosing with the exception of an increase in sleep duration at the dose of 1.2×10(11)VP/kg (p<0.05) but not at lower doses of 2×10(10) and 6×10(10)VP/kg in the hypnotic synergism test. These results demonstrate that administration of rAd5-hTERTC27 was well tolerated in an initial set of safety studies as part of an evaluation to allow human trials for the treatment of HCC.

Chimeric 5/35 adenovirus-mediated Dickkopf-1 overexpression suppressed tumorigenicity of CD44⁺ gastric cancer cells via attenuating Wnt signaling

BACKGROUND

Gastric cancer stem cells (CSCs), which require activation of Wnt signaling to maintain their self-renewal and tumorigenicity, are proposed to be critical targets for effective therapy of gastric carcinomas. Gene therapies that are delivered by adenovirus of serotype 5 (Ad5) or chimeric 5/35(Ad5/35) adenovirus have shown promise for treating various cancers. Here we aimed to develop a gene therapy strategy that targeted gastric CSCs (CD44⁺ cells).

METHODS

CD44⁺ cells were isolated by fluorescence activated cell sorting from both primary gastric cancer cells and cell lines. Expression of adenovirus receptors was examined in CD44⁺ and CD44⁻ cells. A potent Wnt antagonist Dickkopf-1 (DKK1) was delivered into CD44⁺ cells using Ad5/35 (Ad5/35-DKK1). The therapeutic outcomes were evaluated.

RESULTS

Expression of Coxsakievirus adenovirus receptor for Ad5 was significantly reduced, while abundance of CD46, the receptor for Ad5/35, was slightly higher in CD44⁺ cells. Accordingly, CD44⁺ cells were sensitive to Ad5/35 infection, but not to Ad5. Ad5/35-DKK1 introduced DKK1 into CD44⁺ cells and deactivated endogenous Wnt/β-catenin signaling efficiently. Overexpression of DKK1 inhibited survival, anchorage-independent colony formation, and invasion of CD44⁺ cells, which were restored by a GSK-3 specific inhibitor BIO-acetoxime. More importantly, introduction of DKK1 abrogated the tumorigenicity of CD44⁺ cells in vivo. However, Ad5/35-DKK1 only showed minimal cytotoxicity to normal tissue-derived cells, L-02 and GES-1.

CONCLUSIONS

We developed, for the first time, a novel Ad5/35-DKK1-based approach to abrogate Wnt signaling in CSCs and demonstrated that gastric CSC-targeting gene therapy was effective in preclinical experiments.

βKlotho suppresses tumor growth in hepatocellular carcinoma by regulating Akt/GSK-3β/cyclin D1 signaling pathway

βKlotho is a regulator in multiple metabolic processes, while its role in cancer remains unclear. We found the expression of βKlotho was down-regulated in human hepatocellular carcinoma tissues compared with that in paired adjacent non-tumourous liver tissues. Hepatoma cells also showed decreased expression of βKlotho compared with normal hepatocyte cells. Reintroduction of βKlotho into hepatoma cells inhibited their proliferation. The anti-proliferative effect of βKlotho might be linked with G1 to S phase arrest, which was mediated by Akt/GSK-3β/cyclin D1 signaling, since forced expression βKlotho reduced the phosphorylation level of Akt and GSK-3β and induced down-regulation of cyclin D1. Furthermore, βKlotho overexpression could inhibit tumorgenesis, while constitutively activated Akt could override the suppressive effects of βKlotho in vivo. These data suggest βKlotho suppresses tumor growth in hepatocellular carcinoma.

A novel Ad5/11 chimeric oncolytic adenovirus for improved glioma therapy

Effective therapies are needed for malignant glioma patients because of the poor prognosis. Gene therapy combined with virotherapy could be the strategy of choice. In this study, we constructed a modified conditionally replicating adenoviral vector CRAd5/11-Sp-eGFP. The novel vector has the following features: i) the transduction efficiency of CRAd5 was increased using a chimeric fiber 5/11 consisting of an Ad5 tail and an Ad11 shaft and knob; ii) the tumor-specific replication of the vector was improved by utilizing the human survivin promoter to control E1 expression and a poly-A signal inserted right after the inverted terminal repeat (ITR) to stop the non-specific transcriptional activity of the ITR; iii) an expression cassette was inserted into the region between the fiber and E4 region for expressing eGFP. In vitro assays demonstrated that the novel vector could efficiently replicate and kill human glioma cells. Furthermore, CRAd5/11‑Sp-eGFP exhibited significantly increased antitumor effects compared with the control adenoviruses in a xenograft model of glioma. Our results indicate that CRAd5/11-Sp-eGFP represents a promising candidate drug in the treatment of malignant gliomas.

Transcriptional regulators in hepatocarcinogenesis--key integrators of malignant transformation

Hepatocellular carcinoma (HCC) is one of the most frequent human malignancies with poor prognosis and increasing incidence in the Western world. Only for a minority of HCC patients, surgical treatment options offer potential cure and therapeutic success of pharmacological approaches is limited. Highly specific approaches (e.g., kinase inhibitors) did not significantly improve the situation so far, possibly due to functional compensation, genetic heterogeneity of HCC, and development of resistance under selective pressure. In contrast, transcriptional regulators (especially transcription factors and co-factors) may integrate and process input signals of different (oncogenic) pathways and therefore represent cellular bottlenecks that regulate tumor cell biology. In this review, we want to summarize the current knowledge about central transcriptional regulators in human hepatocarcinogenesis and their potential as therapeutic target structures. Genomic and transcriptomic data of primary human HCC revealed that many of these factors showed up in subgroups of HCCs with a more aggressive phenotype, suggesting that aberrant activity of transcriptional regulators collect input information to promote tumor initiation and progression. Therefore, expression and dysfunction of transcription factors and co-factors may gain relevance for diagnostics and therapy of HCC.