PEGylation enhances the tumor selectivity of melanoma-targeted conjugates

The dual interaction of antimicrobial peptides on bacteria and cancer cells; mechanism of action and therapeutic strategies of nanostructures

Microbial infection and cancer are two leading causes of global mortality. Discovering and developing new therapeutics with better specificity having minimal side-effects and no drug resistance are of an immense need. In this regard, cationic antimicrobial peptides (AMP) with dual antimicrobial and anticancer activities are the ultimate choice. For better efficacy and improved stability, the AMPs available for treatment still required to be modified. There are several strategies in which AMPs can be enhanced through, for instance, nano-carrier application with high selectivity and specificity enables researchers to estimate the rate of drug delivery to a particular tissue. In this review we present the biology and modes of action of AMPs for both anticancer and antimicrobial activities as well as some modification strategies to improve the efficacy and selectivity of these AMPs.

Antimicrobial peptides with selective antitumor mechanisms: prospect for anticancer applications

In the last several decades, there have been significant advances in anticancer therapy. However, the development of resistance to cancer drugs and the lack of specificity related to actively dividing cells leading to toxic side effects have undermined these achievements. As a result, there is considerable interest in alternative drugs with novel antitumor mechanisms. In addition to the recent approach using immunotherapy, an effective but much cheaper therapeutic option of pharmaceutical drugs would still provide the best choice for cancer patients as the first line treatment. Ribosomally synthesized cationic antimicrobial peptides (AMPs) or host defense peptides (HDP) display broad-spectrum activity against bacteria based on electrostatic interactions with negatively charged lipids on the bacterial surface. Because of increased proportions of phosphatidylserine (negatively charged) on the surface of cancer cells compared to normal cells, cationic amphipathic peptides could be an effective source of anticancer agents that are both selective and refractory to current resistance mechanisms. We reviewed herein the prospect for AMP application to cancer treatment, with a focus on modes of action of cationic AMPs.

Synthesis and in Vitro and in Vivo Evaluation of MMP-12 Selective Optical Probes

In designing new tracers consisting of a small peptide conjugated to a reporter of comparable size, particular attention needs to be paid to the selection of the reporter group, which can dictate both the in vitro and the in vivo performances of the whole conjugate. In the case of fluorescent tracers, this is particularly true given the large numbers of available dye moieties differing in their structures and properties. Here, we have investigated the in vitro and in vivo properties of a novel series of MMP-12 selective probes composed of cyanine dyes varying in their structure, net charge, and hydrophilic character, tethered through a linker to a potent and specific MMP-12 phosphinic pseudopeptide inhibitor. The impact of linker length has been also explored. The crystallographic structure of one tracer in complex with MMP-12 has been obtained, providing the first crystal structure of a Cy5.5-derived probe and confirming that the binding of the targeting moiety is unaffected. MMP-12 remains the tracers' privileged target, as attested by their affinity selectivity profile evaluated in solution toward a panel of 12 metalloproteases. In vivo assessment of four selected probes has highlighted not only the impact of the dye structure but also that of the linker length on the probes' blood clearance rates and their biodistributions. These experiments have also provided valuable data on the stability of the dye moieties in vivo. This has permitted the identification of one probe, which combines favorable binding to MMP-12 in solution and on cells with optimized in vivo performance including blood clearance rate suitable for short-time imaging. Through this series of tracers, we have identified various critical factors modulating the tracers' in vivo behavior, which is both useful for the development and optimization of MMP-12 selective radiolabeled tracers and informative for the design of fluorescent probes in general.

Small Molecule Radiopharmaceuticals - A Review of Current Approaches

Radiopharmaceuticals are an integral component of nuclear medicine and are widely applied in diagnostics and therapy. Though widely applied, the development of an “ideal” radiopharmaceutical can be challenging. Issues such as specificity, selectivity, sensitivity, and feasible chemistry challenge the design and synthesis of radiopharmaceuticals. Over time, strategies to address the issues have evolved by making use of new technological advances in the fields of biology and chemistry. This review presents the application of few advances in design and synthesis of radiopharmaceuticals. The topics covered are bivalent ligand approach and lipidization as part of design modifications for enhanced selectivity and sensitivity and novel synthetic strategies for optimized chemistry and radiolabeling of radiopharmaceuticals.