Nanotechnology has the potential to revolutionize cancer diagnosis and therapy. Advances in protein engineering and materials science have contributed to novel nanoscale targeting approaches that may bring new hope to cancer patients. Several therapeutic nanocarriers have been approved for clinical use. However, to date, there are only a few clinically approved nanocarriers that incorporate molecules to selectively bind and target cancer cells. This review examines some of the approved formulations and discusses the challenges in translating basic research to the clinic. We detail the arsenal of nanocarriers and molecules available for selective tumour targeting, and emphasize the challenges in cancer treatment.

Nanocarriers as an emerging platform for cancer therapy

Peptides or proteins convert under some conditions from their soluble forms into highly ordered fibrillar aggregates. Such transitions can give rise to pathological conditions ranging from neurodegenerative disorders to systemic amyloidoses. In this review, we identify the diseases known to be associated with formation of fibrillar aggregates and the specific peptides and proteins involved in each case. We describe, in addition, that living organisms can take advantage of the inherent ability of proteins to form such structures to generate novel and diverse biological functions. We review recent advances toward the elucidation of the structures of amyloid fibrils and the mechanisms of their formation at a molecular level. Finally, we discuss the relative importance of the common main-chain and side-chain interactions in determining the propensities of proteins to aggregate and describe some of the evidence that the oligomeric fibril precursors are the primary origins of pathological behavior.

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Protein Misfolding, Functional Amyloid, and Human Disease

Each year, the American Cancer Society estimates the number of new cancer cases and deaths expected in the United States in the current year and compiles the most recent data on cancer incidence, mortality, and survival based on incidence data from the National Cancer Institute and mortality data from the National Center for Health Statistics. Incidence and death rates are age-standardized to the 2000 US standard million population. A total of 1,399,790 new cancer cases and 564,830 deaths from cancer are expected in the United States in 2006. When deaths are aggregated by age, cancer has surpassed heart disease as the leading cause of death for those younger than age 85 since 1999. Delay-adjusted cancer incidence rates stabilized in men from 1995 through 2002, but continued to increase by 0.3% per year from 1987 through 2002 in women. Between 2002 and 2003, the actual number of recorded cancer deaths decreased by 778 in men, but increased by 409 in women, resulting in a net decrease of 369, the first decrease in the total number of cancer deaths since national mortality record keeping was instituted in 1930. The death rate from all cancers combined has decreased by 1.5% per year since 1993 among men and by 0.8% per year since 1992 among women. The mortality rate has also continued to decrease for the three most common cancer sites in men (lung and bronchus, colon and rectum, and prostate) and for breast and colon and rectum cancers in women. Lung cancer mortality among women continues to increase slightly. In analyses by race and ethnicity, African American men and women have 40% and 18% higher death rates from all cancers combined than White men and women, respectively. Cancer incidence and death rates are lower in other racial and ethnic groups than in Whites and African Americans for all sites combined and for the four major cancer sites. However, these groups generally have higher rates for stomach, liver, and cervical cancers than Whites. Furthermore, minority populations are more likely to be diagnosed with advanced stage disease than are Whites. Progress in reducing the burden of suffering and death from cancer can be accelerated by applying existing cancer control knowledge across all segments of the population.

https://onlinelibrary.wiley.com/doi/pdf/10.3322/canjclin.56.2.106

Cancer statistics, 2006.

The manner in which a newly synthesized chain of amino acids transforms itself into a perfectly folded protein depends both on the intrinsic properties of the amino-acid sequence and on multiple contributing influences from the crowded cellular milieu. Folding and unfolding are crucial ways of regulating biological activity and targeting proteins to different cellular locations. Aggregation of misfolded proteins that escape the cellular quality-control mechanisms is a common feature of a wide range of highly debilitating and increasingly prevalent diseases.

Protein folding and misfolding

Using the atomic structures of the large ribosomal subunit from Haloarcula marismortui and its complexes with two substrate analogs, we establish that the ribosome is a ribozyme and address the catalytic properties of its all-RNA active site. Both substrate analogs are contacted exclusively by conserved ribosomal RNA (rRNA) residues from domain V of 23S rRNA; there are no protein side-chain atoms closer than about 18 angstroms to the peptide bond being synthesized. The mechanism of peptide bond synthesis appears to resemble the reverse of the acylation step in serine proteases, with the base of A2486 (A2451 in Escherichia coli) playing the same general base role as histidine-57 in chymotrypsin. The unusual pK(a) (where K(a) is the acid dissociation constant) required for A2486 to perform this function may derive in part from its hydrogen bonding to G2482 (G2447 in E. coli), which also interacts with a buried phosphate that could stabilize unusual tautomers of these two bases. The polypeptide exit tunnel is largely formed by RNA but has significant contributions from proteins L4, L22, and L39e, and its exit is encircled by proteins L19, L22, L23, L24, L29, and L31e.

The Structural Basis of Ribosome Activity in Peptide Bond Synthesis

Dromedary immune response and specific Kv2.1 antibody generation using a specific immunization approach.

Significant progress has been made in immunological studies of scorpion toxins and several formats of antibodies directed against scorpion toxins have been reported. Some of these are commonly used in a specific treatment against envenoming; others are primarily used for immuno-biochemical characterizations. The preparation protocol of the antibody or its fragments can be substantially different from one laboratory to another, which complicates a direct comparison of the potency of the antivenom. The use of immune sera, the total immunoglobulin fraction or Fab and Fab'2 fragments as the therapeutic agent is widespread. A number of monoclonal antibodies have also been reported and used for engineering of Fv, ScFv or Fab fragments. Recently, a novel antibody format - known as nanobodies - derived from HCAbs of camelids and selected after phage display shows great potential to provide a more efficient therapy against scorpion envenoming. Subsequent bispecific derivatives have been designed and their pharmacokinetics have been studied. Distinct advantages and disadvantages have been attributed to these equine, murine or camelid antibodies and their derived fragments. Some fragments are easily amenable into next generation therapeutics after proper manufacturing and provide an ensured availability of the product to the medical community. Through examples, we will show how the comparison of the serotherapeutic effectiveness is compromised due to the absence of standardization, on the preparation of immunogens, production processes and / or nature of the products. We will report on recent advances in the field.

Immunological Aspects of Scorpion Toxins: Current Status and Perspectives

The invention relates to a recognition molecule, being capable of interacting with an active site or cleft of a target molecule, which recognition molecule comprises an exposed loop structure, which extends from a basic recognition unit. The loop structure is for example the CDR3 of a camelid species heavy chain antibody having a binding specificity fo the active site or cleft of a target molecule, or a derived version of such a CDR3. The basic recognition unit is for example formed by an antibody-type structure having binding affinity for the target molecule.

Antibody molecules which interact specifically with the active site or cleft of a target molecule

Several authors, including ourselves, have reported the existence of chromatosomes with DNA size larger than 166 bp in bird erythrocyte chromatin. It was tempting to correlate this increased DNA size with the presence of histone H5. In order to substantiate this hypothesis, we performed a micrococcal nuclease digestion kinetic on: chicken erythrocyte chromatin, either native, selectively depleted from H1, or from H1 and H5; and rat liver chromatin, either native or partially H1 depleted. The comparative analysis of the lengths of DNA in the chromatosome size region led to the following conclusions: - denaturing gels clearly reveal a first discrete pause at 178 nucleotides in H1 depleted chicken erythrocyte chromatin as well as in partially H1-depleted rat liver chromatin, before the material accumulates at the next intermediate 166 nucleotide chromatosome pause. - the generation of all discrete chromatosome bands is critically dependent on low ionic strength conditions and low Ca++ concentrations during the digestion, suggesting it may result from the protection of DNA cleavage sites by histone H5 or H1, C or N terminal domains.

Serge Muyldermans

Papers

Dromedary immune response and specific Kv2.1 antibody generation using a specific immunization approach.

Immunological Aspects of Scorpion Toxins: Current Status and Perspectives

Antibody molecules which interact specifically with the active site or cleft of a target molecule

Protection of discrete DNA fragments by the complex Hl-octamerhistones or H5-octamerhistonesafter micrococcal nuclease digestion

cDNA sequence coding for the constant region of the dromedary gamma 3 heavy chain antibody