Redirecting extracellular proteases to molecularly guide radiosensitizing drugs to tumors.

Patients with advanced cancers are treated with combined radiotherapy and chemotherapy, however curability is poor and treatment side effects severe. Drugs sensitizing tumors to radiotherapy have been developed to improve cell kill, but tumor specificity remains challenging. To achieve tumor selectivity of small molecule radiosensitizers, we tested as a strategy active tumor targeting using peptide-based drug conjugates.

APTO-253 Is a New Addition to the Repertoire of Drugs that Can Exploit DNA BRCA1/2 Deficiency.

APTO-253 is a small molecule with antiproliferative activity against cell lines derived from a wide range of human malignancies. We sought to determine the mechanisms of action and basis for resistance to APTO-253 so as to identify synthetic lethal interactions that can guide combination studies. The cellular pharmacology of APTO-253 was analyzed in Raji lymphoma cells and a subline selected for resistance (Raji/253R).

Laminin targeting of a peripheral nerve-highlighting peptide enables degenerated nerve visualization.

Target-blind activity-based screening of molecular libraries is often used to develop first-generation compounds, but subsequent target identification is rate-limiting to developing improved agents with higher specific affinity and lower off-target binding. A fluorescently labeled nerve-binding peptide, NP41, selected by phage display, highlights peripheral nerves in vivo. Nerve highlighting has the potential to improve surgical outcomes by facilitating intraoperative nerve identification, reducing accidental nerve transection, and facilitating repair of damaged nerves.

A far-red fluorescent protein evolved from a cyanobacterial phycobiliprotein.

Far-red fluorescent proteins (FPs) are desirable for in vivo imaging because with these molecules less light is scattered, absorbed, or re-emitted by endogenous biomolecules compared with cyan, green, yellow, and orange FPs. We developed a new class of FP from an allophycocyanin α-subunit (APCα). Native APC requires a lyase to incorporate phycocyanobilin.

PKMζ, but not PKCλ, is rapidly synthesized and degraded at the neuronal synapse.

Synthesizing, localizing, and stabilizing new protein copies at synapses are crucial factors in maintaining the synaptic changes required for storing long-term memories. PKMζ recently emerged as a molecule putatively responsible for maintaining encoded memories over time because its presence correlates with late LTP and because its inhibition disrupts LTP in vitro and long-term memory storage in vivo. Here we investigated PKMζ stability in rat neurons to better understand its role during information encoding and storage.

Altered backbone and side-chain interactions result in route heterogeneity during the folding of interleukin-1β (IL-1β).

Deletion of the β-bulge trigger-loop results in both a switch in the preferred folding route, from the functional loop packing folding route to barrel closure, as well as conversion of the agonist activity of IL-1β into antagonist activity. Conversely, circular permutations of IL-1β conserve the functional folding route as well as the agonist activity. These two extremes in the folding-functional interplay beg the question of whether mutations in IL-1β would result in changes in the populations of heterogeneous folding routes and the signaling activity.

Fluorescent peptides highlight peripheral nerves during surgery in mice.

Nerve preservation is an important goal during surgery because accidental transection or injury leads to significant morbidity, including numbness, pain, weakness or paralysis. Nerves are usually identified by their appearance and relationship to nearby structures or detected by local electrical stimulation (electromyography), but thin or buried nerves are sometimes overlooked. Here, we use phage display to select a peptide that binds preferentially to nerves.

Parallel in vivo and in vitro selection using phage display identifies protease-dependent tumor-targeting peptides.

We recently developed activatable cell-penetrating peptides (ACPPs) that target contrast agents to in vivo sites of matrix metalloproteinase activity, such as tumors. Here we use parallel in vivo and in vitro selection with phage display to identify novel tumor-homing ACPPs with no bias for primary sequence or target protease. Specifically, phage displaying a library of ACPPs were either injected into tumor-bearing mice, followed by isolation of cleaved phage from dissected tumor, or isolated based on selective cleavage by extracts of tumor versus normal tissue.

In vivo characterization of activatable cell penetrating peptides for targeting protease activity in cancer.

Activatable cell penetrating peptides (ACPPs) are novel in vivo targeting agents comprised of a polycationic cell penetrating peptide (CPP) connected via a cleavable linker to a neutralizing polyanion (). Adsorption and uptake into cells are inhibited until the linker is proteolyzed. An ACPP cleavable by matrix metalloproteinase-2 (MMP-2) in vitro was the first one demonstrated to work in a tumor model in vivo, but only HT-1080 xenografts and resected human squamous cell carcinomas were tested.

Autofluorescent proteins with excitation in the optical window for intravital imaging in mammals.

Fluorescent proteins have become valuable tools for biomedical research as protein tags, reporters of gene expression, biosensor components, and cell lineage tracers. However, applications of fluorescent proteins for deep tissue imaging in whole mammals have been constrained by the opacity of tissues to excitation light below 600 nm, because of absorbance by hemoglobin. Fluorescent proteins that excite efficiently in the "optical window" above 600 nm are therefore highly desirable.

Temperature, media, and point of induction affect the N-terminal processing of interleukin-1beta.

The expression of recombinant proteins in bacterial hosts may alter the biophysical properties of the protein of interest as a result of differences in post-translational processing from that observed when produced in the native cell. For example, recombinant human interleukin-1beta (IL-1beta) is produced as three isoforms when expressed in the Escherichia coli strain BL-21(DE3). These isoforms are produced by the non-homogeneous processing of the N-terminal methionine residue by the endogenous bacterial aminopeptidase and differ in the first residue (1-met, 1-ala, and 1-pro).

New biarsenical ligands and tetracysteine motifs for protein labeling in vitro and in vivo: synthesis and biological applications.

We recently introduced a method (Griffin, B. A.; Adams, S.