Selection of tumour specific promoters for adenoviral gene therapy of cholangiocarcinoma

Potentials of ribosomopathy gene as pharmaceutical targets for cancer treatment

Ribosomopathies encompass a spectrum of disorders arising from impaired ribosome biogenesis and reduced functionality. Mutation or dysexpression of the genes that disturb any finely regulated steps of ribosome biogenesis can result in different types of ribosomopathies in clinic, collectively known as ribosomopathy genes. Emerging data suggest that ribosomopathy patients exhibit a significantly heightened susceptibility to cancer. Abnormal ribosome biogenesis and dysregulation of some ribosomopathy genes have also been found to be intimately associated with cancer development. The correlation between ribosome biogenesis or ribosomopathy and the development of malignancies has been well established. This work aims to review the recent advances in the research of ribosomopathy genes among human cancers and meanwhile, to excavate the potential role of these genes, which have not or rarely been reported in cancer, in the disease development across cancers. We plan to establish a theoretical framework between the ribosomopathy gene and cancer development, to further facilitate the potential of these genes as diagnostic biomarker as well as pharmaceutical targets for cancer treatment.

Chemoresistance and resistance to targeted therapies in biliary tract cancer: What have we learned?

INTRODUCTION

Biliary tract cancer (BTC), including intra- and extrahepatic cholangiocarcinoma and gallbladder cancer, is a rare and highly difficult to manage human malignancy. Besides late diagnosis and associated unresectability, frequently observed unresponsiveness towards and recurrence following chemotherapy or targeted therapy essentially contribute to the dismal prognosis of BTC patients.

AREAS COVERED

The review provides an update on individual mechanisms involved resistance of BTC towards conventional chemotherapy as well as targeted therapies. We review the distinct mechanisms of pharmacoresistance (MPRs) which have been defined in BTC cells on a molecular basis and examine the specific consequences for the various approaches of chemo-, targeted or immunomodulatory therapies.

EXPERT OPINION

Based on currently available experimental and clinical data, the present knowledge about these MPRs in BTCs are summarized. While some possible tactics for overcoming these mechanisms of resistance have been investigated, a BTC-specific and efficient approach based on comprehensive in vitro and in vivo experimental systems is not yet available. Additionally, a reliable monitoring of therapy-relevant cellular changes needs to be established which allows for choosing the optimal drug (combination) before and/or during pharmacological therapy.

Signalling networks in cholangiocarcinoma: Molecular pathogenesis, targeted therapies and drug resistance

Cholangiocarcinoma (CCA) is a deadly disease. While surgery may attain cure in a minor fraction of cases, therapeutic options in either the adjuvant or advanced setting are limited. The possibility of advancing the efficacy of therapeutic approaches to CCA relies on understanding its molecular pathogenesis and developing rational therapies aimed at interfering with oncogenic signalling networks that drive and sustain cholangiocarcinogenesis. These efforts are complicated by the intricate biology of CCA, which integrates not only the driving force of tumour cell-intrinsic alterations at the genetic and epigenetic level but also pro-tumorigenic cues conveyed to CCA cells by different cell types present in the rich tumour stroma. Herein, we review our current understanding of the mechanistic bases underpinning the activation of major oncogenic pathways causative of CCA pathogenesis. We subsequently discuss how this knowledge is being exploited to implement rationale-based and genotype-matched therapeutic approaches that predictably will radically transform CCA clinical management in the next decade. We conclude by highlighting the mechanisms of therapeutic resistance in CCA and reviewing innovative approaches to combat resistance at the preclinical and clinical level.

High promoter activity of cytokeratin-19 gene in cholangiocarcinoma

Conditionally replicating adenoviral vectors constructed with tumor-specific promoters (TSPs) offers a viable tool for the treatment of cholangiocarcinoma. The aim of the present study was to investigate cholangiocarcinoma-specific TSPs that remain active in adenoviral constructs in gene therapy. The mRNA expressions of cyclooxygenase-2, cytokeratin-19 (CK19), mucin-1, midkine and telomerase reverse transcriptase were determined in human cholangiocarcinoma cell lines, primary human hepatocytes and cholangiocytes using reverse transcription-quantitative polymerase chain reaction. The candidate promoters constructed in adenoviral vectors were analyzed for their activities in cholangiocarcinoma cell lines, primary human hepatocytes and cholangiocytes using dual-luciferase reporter assays. The mRNA expression of CK19 was markedly higher in the QBC939 cell line, indicating specificity to cholangiocarcinoma. Moreover, the promoter activity of CK19 in the adenoviral vector in infected cholangiocarcinoma cells was found to be significantly stronger compared with that in infected primary human hepatocytes and cholangiocytes. CK19 may be implicated in the pathogenesis of cholangiocarcinoma, as demonstrated by the stronger activity of its promoter, as well as the higher expression of mRNA in tumor cells. Therefore, the use of the promoter sequence of the CK19 gene may represent a potential tool in cholangiocarcinoma-specific adenoviral gene therapy.

Chemoresistance and chemosensitization in cholangiocarcinoma

One of the main difficulties in the management of patients with advanced cholangiocarcinoma (CCA) is their poor response to available chemotherapy. This is the result of powerful mechanisms of chemoresistance (MOC) of quite diverse nature that usually act synergistically. The problem is often worsened by altered MOC gene expression in response to pharmacological treatment. Since CCA includes a heterogeneous group of cancers their genetic signature coding for MOC genes is also diverse; however, several shared traits have been defined. Some of these characteristics are shared with other types of liver cancer, namely hepatocellular carcinoma and hepatoblastoma. An important goal in modern oncologic pharmacology is to develop novel strategies to overcome CCA chemoresistance either by increasing drug specificity, such as in targeted therapies aimed to inhibit receptors with tyrosine kinase activity, or to increase the amounts of active agents inside CCA cells by enhancing drug uptake or reducing efflux through export pumps. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

A Multiantigenic DNA Vaccine That Induces Broad Hepatitis C Virus-Specific T-Cell Responses in Mice

There are 3 to 4 million new hepatitis C virus (HCV) infections annually around the world, but no vaccine is available. Robust T-cell mediated responses are necessary for effective clearance of the virus, and DNA vaccines result in a cell-mediated bias. Adjuvants are often required for effective vaccination, but during natural lytic viral infections damage-associated molecular patterns (DAMPs) are released, which act as natural adjuvants. Hence, a vaccine that induces cell necrosis and releases DAMPs will result in cell-mediated immunity (CMI), similar to that resulting from natural lytic viral infection. We have generated a DNA vaccine with the ability to elicit strong CMI against the HCV nonstructural (NS) proteins (3, 4A, 4B, and 5B) by encoding a cytolytic protein, perforin (PRF), and the antigens on a single plasmid. We examined the efficacy of the vaccines in C57BL/6 mice, as determined by gamma interferon enzyme-linked immunosorbent spot assay, cell proliferation studies, and intracellular cytokine production. Initially, we showed that encoding the NS4A protein in a vaccine which encoded only NS3 reduced the immunogenicity of NS3, whereas including PRF increased NS3 immunogenicity. In contrast, the inclusion of NS4A increased the immunogenicity of the NS3, NS4B, andNS5B proteins, when encoded in a DNA vaccine that also encoded PRF. Finally, vaccines that also encoded PRF elicited similar levels of CMI against each protein after vaccination with DNA encoding NS3, NS4A, NS4B, and NS5B compared to mice vaccinated with DNA encoding only NS3 or NS4B/5B. Thus, we have developed a promising "multiantigen" vaccine that elicits robust CMI.

IMPORTANCE

Since their development, vaccines have reduced the global burden of disease. One strategy for vaccine development is to use commercially viable DNA technology, which has the potential to generate robust immune responses. Hepatitis C virus causes chronic liver infection and is a leading cause of liver cancer. To date, no vaccine is currently available, and treatment is costly and often results in side effects, limiting the number of patients who are treated. Despite recent advances in treatment, prevention remains the key to efficient control and elimination of this virus. Here, we describe a novel DNA vaccine against hepatitis C virus that is capable of inducing robust cell-mediated immune responses in mice and is a promising vaccine candidate for humans.

Gene therapy in The Netherlands: highlights from the Low Countries

Gene therapy is an active research area in The Netherlands and Dutch scientists involved in fundamental and clinical gene therapy research significantly contribute to the progresses made in this field. This ranges from the establishment of the 293, 911 and PER.C6 cell lines, which are used worldwide for the production of replication‐defective adenoviral vectors, to the development of targeted viral vectors and T lymphocytes as well as of non‐viral vectors. Several milestones have been achieved in Dutch clinical gene therapy trials, including the first treatment worldwide of patients with adenosine deaminase deficiency with genetically corrected hematopoietic stem cells in collaboration with French and British scientists. Until now, about 230 patients with various diseases have been treated with viral and non‐viral gene therapy in this country. Ongoing and upcoming Dutch clinical trials focus on the translation of new developments in gene therapy research, including the restoration of genetic defects other than SCID, and the use of oncolytic adenoviruses and targeted T cells for the treatment of cancer. The growing commercial interest in Dutch clinical gene therapy is reflected by the involvement of two Dutch companies in ongoing trials as well as the participation of Dutch clinical centres in large phase III international multicenter immuno‐gene therapy trials on prostate cancer sponsored by an American company. Translational gene therapy research in The Netherlands is boosted at a governmental level by the Dutch Ministry of Health via a dedicated funding programme. This paper presents an overview on milestones in Dutch basic gene therapy research as well as on past, present and future clinical gene therapy trials in The Netherlands. Copyright © 2007 John Wiley & Sons, Ltd.