Nonviral
Gene Therapy and its Delivery Systems Pp.1-17
Antibody
Engineering for Targeted Therapy of Cancer: Recombinant Fv-Immunotoxins Pp.19-46
Revital Niv, Cyril
J. Cohen, Galit Denkberg, Dina Segal and Yoram Reiter
Genetically
Modified Viruses: Vaccines by Design Pp. 47-76
John R.
Stephenson
Small
Heat Shock Proteins (sHSPs) As Potential Drug Targets Pp. 77-111
M. James C.
Crabbe and Henry W. Hepburne-Scott
[Back to top] Nonviral Gene Therapy and its Delivery
Systems
Haiching
Ma and Scott L. Diamond
Nonviral gene therapy has significant clinical potential,
yet its therapeutic utility has been hindered by low transfection efficiency
due to a combination of extracellular and intracellular barriers. Recent developments
in formulation and delivery methodology have allowed a number of advances
toward high efficiency gene delivery to various cell types and organs. In
particular, the extracellular and intracellular pharmacokinetics of plasmid DNA
trafficking are better understood in a number of cell systems. Using cationic
lipid or polymers (often with receptor targeting), more than 105 plasmids can be delivered to a single cell. Endosomolytic agents
promote endosome disruption, and include: weak bases, proton-sponge polymers,
fusogenic peptides, viral particles, and photosensitizing compounds. Both
classical and nonclassical nuclear localization signal (NLS) peptides have also
been tested for enhancement of the probability of nuclear import events, a
major rate-limiting step in DNA delivery to nondividing cells. For example, the
M9 sequence from heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) protein,
a non-classical NLS, has been found to increase gene expression level by more
than 10 to 150-fold in a variety of cell types. This review will concentrate on
the current understandings of the basic mechanisms of nonviral gene
delivery and new approaches in the field.
[Back to top] Antibody Engineering for
Targeted Therapy of Cancer: Recombinant Fv-Immunotoxins
Revital
Niv, Cyril J. Cohen, Galit Denkberg, Dina Segal and Yoram Reiter
Recombinant
Fv-immunotoxins are a new class of biologic anticancer agents composed of a
recombinant antibody fragment linked to a very potent bacterial toxin. These
potent molecules are designed to specifically bind and kill cancer cells that
express a specific target antigen on their cell surface. Recombinant
Fv-immunotoxins are an excellent example for the concept of rational drug
design. They combine the progress in understanding cancer biology, -the recent
knowledge on the mechanisms of malignant transformation and the special
properties of cancer cells, -with the enormous developments in recombinant DNA
technology and antibody engineering.
Recombinant Fv
immunotoxins were developed for solid tumors and hematological malignancies and
have been characterized intensively for their biological activity in vitro and
in vivo in animal models. The excellent in vitro and in vivo activities
of recombinant Fv-immunotoxins have lead to their pre-clinical development and
to the initiation of clinical trial protocols.
Recent trials have
demonstrated potent clinical efficacy in patients with malignant diseases that
are refractory to traditional modalities of cancer treatment.
It is thus suggested that this strategy can be developed into a separate modality of cancer treatment with the basic rationale of specifically targeting cancer cells on the basis of their unique surface markers combined with potent effective biological toxic agents that directly kill the cancer cell. Efforts are now being made to improve the current molecules and to develop new agents with better clinical efficacy. In this review, we will describe the rationale in designing Fv-immunotoxins and will review current progress made in using thes agents for cancer treatment.
[Back to top] Genetically Modified Viruses:
Vaccines by Design
John
R. Stephenson
.
Vaccination has been one of the most successful and cost-effective health interventions ever employed. One disease (smallpox) has been eradicated, another (poliomyelitis) should disappear early in the new millennium and a third (measles) should follow shortly after. Conventional vaccines usually depend on one of three development processes, attenuation of virulent organisms (by passage in cell culture and/or experimental animals), killing of virulent organisms (by chemical inactivation) or the purification of immunogenic molecules (either proteins or carbohydrates) from whole organisms.
These traditional processes, although serendipitous and poorly understood, have produced effective pharmaceutical products which give excellent protection against diseases such as smallpox, rabies, measles, yellow fever, tetanus and diphtheria. In spite of these successes however, the application of these protocols have failed to produce safe and efficacious vaccines against other infectious diseases which kill or maim tens of millions of people every year. The most important of these are malaria, AIDS, herpes, dengue fever and some forms of viral hepatitis.
Consequently, fundamentally new technologies are required to tackle these important infections. One of the most promising has been the development of genetically modified viruses. This process normally involves taking a proven safe and efficacious vaccine virus, such as vaccinia or adenovirus, and modifying its genome to include genes coding for immunogenic proteins from other viruses such as HIV or measles. This review will describe the generation of such novel vaccine vectors and compare their advantages and shortcomings. In addition the literature describing their use as experimental vaccines will also be reviewed.
[Back to top] Small Heat Shock Proteins (sHSPs) As
Potential Drug Targets
M.
James C. Crabbe and Henry W. Hepburne-Scott
Small heat shock
proteins (sHSPs) belong to a family of 12- to 43-kDa proteins that are
ubiquitous and are largely conserved in amino acid sequence among all
organisms.
The principal
heat-shock proteins that have chaperone activity (that is, they protect newly
made proteins from misfolding) belong to five conserved classes: HSP100, HSP90,
HSP70, HSP60 and the small heat-shock proteins (sHSPs). The sHSPs (which
include alpha crystallin) can form large multimeric structures and have a wide
range of cellular functions, including endowing cells with thermotolerance in
vivo and being able to act as molecular chaperones in vitro; sHSPs do this by
forming stable complexes with folding or unfolding- intermediates of their
protein substrates, probably the molten globule.
This paper
includes: a brief survey of the chaperone family, the small heat shock protein
superfamily, transcription of sHSPs, sequence comparisons and structural models
of small heat shock proteins structural elements as potential drug targets,
sHSPs as chaperone-like proteins, alpha crystallin chaperone-like activity,
conformational diseases the role of alpha crystallin small heat shock protein
superfamily proteins, post-translational modification and useful
pharmacological agents.
Functionality of
small heat shock proteins targets and diseases where pharmacologically active
agents are of importance, alpha crystallin- small heat shock proteins and prion
diseases: specific targets for diagnostic tests and drug development, details
of some specific small heat shock proteins as drug targets, structural and
functional implications for treatment.