Doxorubicin-Loaded Micelle Targeting MUC1: A Potential Therapeutic for MUC1 Triple Negative Breast Cancer Treatment.

BACKGROUND: Triple negative breast cancer (TNBC) is an aggressive disease associated with poor prognosis and lack of validated targeted therapy. Thus chemotherapy is a main adjuvant treatment for TNBC patients, but it associates with severe toxicities. For a better treatment outcome, we developed an alternative therapeutic, doxorubicin (DOX)-loaded micelles targeting human mucin1 protein (MUC1) that is less toxic, more effective and targeted to TNBC. METHODS: From many candidate peptides, QNDRHPR-GGGSK (QND) and HSQLPQV-GGGSK (HSQ) were identified computationally, synthesized and purified using solid phase peptide synthesis and semipreparative HPLC. The peptides showed significant high binding to MUC1 expressing cells using a fluorescent microscope. The peptides were then conjugated on pegylated octadecyl lithocholate copolymer. DOX-encapsulated micelles were formed through self-assembly. MUC1-targeted micelles were characterized using dynamic light scattering (DLS) and Transmission Electron Microscopy (TEM). Drug entrapment efficiency was examined using a microplate reader. Cytotoxicity, binding, and uptake were also investigated. RESULTS: Two types of DOX-loaded micelles with different targeting peptides, QND or HSQ, were developed. DOX-loaded micelles were spherical in shape with average particle size around 300-320 nm. Drug entrapment efficiency of untargeted and targeted DOX micelles was about 71-93%. Targeted QND-DOX and HSQ-DOX micelles exhibited significantly higher cytotoxicity compared to free DOX and untargeted DOX micelles on BT549-Luc cells. In addition, significantly greater binding and uptake were observed for QND-DOX and HSQ-DOX micelles on BT549-Luc and T47D cells. CONCLUSION: Taken together, these results suggested that QND-DOX and HSQ-DOX micelles have a potential application in the treatment of TNBC-expressing MUC1.

Targeted therapy of colorectal neoplasia with rapamycin in peptide-labeled pegylated octadecyl lithocholate micelles.

Many powerful drugs have limited clinical utility because of poor water solubility and high systemic toxicity. Here, we formulated a targeted nanomedicine, rapamycin encapsulated in pegylated octadecyl lithocholate micelles labeled with a new ligand for colorectal neoplasia, LTTHYKL peptide. CPC;Apc mice that spontaneously develop colonic adenomas were treated with free rapamycin, plain rapamycin micelles, and peptide-labeled rapamycin micelles via intraperitoneal injection for 35days. Endoscopy was performed to monitor adenoma regression in vivo. We observed complete adenoma regression at the end of therapy. The mean regression rate for peptide-labeled rapamycin micelles was significantly greater than that for plain rapamycin micelles, P<0.01. On immunohistochemistry, we observed a significant reduction in phospho-S6 but not ß-catenin expression and reduced tumor cell proliferation, suggesting greater inhibition of downstream mTOR signaling. We observed significantly reduced renal toxicity for peptide-labeled rapamycin micelles compared to that of free drug, and no other toxicities were found on chemistries. Together, this unique targeted micelle represents a potential therapeutic for colorectal neoplasia with comparable therapeutic efficacy to rapamycin free drug and significantly less systemic toxicity.

Targeted imaging of esophageal neoplasia with a fluorescently labeled peptide: first-in-human results.

Esophageal adenocarcinoma is rising rapidly in incidence and usually develops from Barrett's esophagus, a precursor condition commonly found in patients with chronic acid reflux. Premalignant lesions are challenging to detect on conventional screening endoscopy because of their flat appearance. Molecular changes can be used to improve detection of early neoplasia. We have developed a peptide that binds specifically to high-grade dysplasia and adenocarcinoma. We first applied the peptide ex vivo to esophageal specimens from 17 patients to validate specific binding. Next, we performed confocal endomicroscopy in vivo in 25 human subjects after topical peptide administration and found 3.8-fold greater fluorescence intensity for esophageal neoplasia compared with Barrett's esophagus and squamous epithelium with 75% sensitivity and 97% specificity. No toxicity was attributed to the peptide in either animal or patient studies. Therefore, our first-in-human results show that this targeted imaging agent is safe and may be useful for guiding tissue biopsy and for early detection of esophageal neoplasia and potentially other cancers of epithelial origin, such as bladder, colon, lung, pancreas, and stomach.

Progress in molecular imaging in endoscopy and endomicroscopy for cancer imaging.

Imaging is an essential tool for effective cancer management. Endoscopes are important medical instruments for performing in vivo imaging in hollow organs. Early detection of cancer can be achieved with surveillance using endoscopy, and has been shown to reduce mortality and to improve outcomes. Recently, great advancements have been made in endoscopic instruments, including new developments in optical designs, light sources, optical fibers, miniature scanners, and multimodal systems, allowing for improved resolution, greater tissue penetration, and multispectral imaging. In addition, progress has been made in the development of highly-specific optical probes, allowing for improved specificity for molecular targets. Integration of these new endoscopic instruments with molecular probes provides a unique opportunity for significantly improving patient outcomes and has potential to further improve early detection, image guided therapy, targeted therapy, and personalized medicine. This work summarizes current and evolving endoscopic technologies, and provides an overview of various promising optical molecular probes.

Targeted vertical cross-sectional imaging with handheld near-infrared dual axes confocal fluorescence endomicroscope.

We demonstrate vertical cross-sectional (XZ-plane) images of near-infrared (NIR) fluorescence with a handheld dual axes confocal endomicroscope that reveals specific binding of a Cy5.5-labeled peptide to pre-malignant colonic mucosa. This view is perpendicular to the tissue surface, and is similar to that used by pathologists. The scan head is 10 mm in outer diameter (OD), and integrates a one dimensional (1-D) microelectromechanical systems (MEMS) X-axis scanner and a bulky lead zirconate titanate (PZT) based Z-axis actuator. The microscope images in a raster-scanning pattern with a ±6 degrees (mechanical) scan angle at ~3 kHz in the X-axis (fast) and up to 10 Hz (0-400 µm) in the Z-axis (slow). Vertical cross-sectional fluorescence images are collected with a transverse and axial resolution of 4 and 5 µm, respectively, over a field-of-view of 800 µm (width) × 400 µm (depth). NIR vertical cross-sectional fluorescence images of fresh mouse colonic mucosa demonstrate histology-like imaging performance with this miniature instrument.

Noncovalent PEGylation by polyanion complexation as a means to stabilize keratinocyte growth factor-2 (KGF-2).

Repifermin, a truncated form of fibroblast growth factor-10 (FGF-10) also known as keratinocyte growth factor-2 (KGF-2), is a heparin-binding protein with potent regenerative properties. The protein unfolds and aggregates at relatively low temperature (~37 °C). Electrostatic interactions between polyanions and several FGFs have been reported to enhance the thermal stability of these proteins. Polyethylene glycol (PEG) was grafted to the polyanions pentosan polysulfate (PPS) and dextran sulfate (DS) as an alternative means to stabilize and noncovalently PEGylate KGF-2. Physical characteristics of KGF-2:polyanion-PEG complexes were examined using a variety of methods including circular dichroism (CD), intrinsic tryptophan fluorescence, differential scanning calorimetry, and dynamic light scattering. When compared to KGF-2 alone, subtle changes in CD spectra and fluorescence emission maxima were found when KGF-2 was formulated with the synthetic PEG-polyanions. Highly PEGylated polyanions (DS-PEG5) did not bind KGF-2 as well as conjugates with fewer PEG chains. The molecular weight of PEG did not have a noticeable effect on KGF-2 binding to the various PEG-polyanion conjugates. At optimal molar ratios, PPS-PEG and DS-PEG conjugates were able to stabilize KGF-2 by increasing the melting temperature by approximately 9-17 °C. Thus, polyanion-PEG conjugates improved the stability of KGF-2 and also offered a new electrostatic PEGylation scheme that may be extrapolated to other heparin-binding proteins.

Calcium condensed LABL-TAT complexes effectively target gene delivery to ICAM-1 expressing cells.

Targeted gene delivery using nonviral vectors is a highly touted scheme to reduce the potential for toxic or immunological side effects by reducing dose. In previous reports, TAT polyplexes with DNA have shown relatively poor gene delivery. The transfection efficiency has been enhanced by condensing TAT/DNA complexes to a small particle size using calcium. To explore the targetability of these condensed TAT complexes, LABL peptide targeting intercellular cell-adhesion molecule-1 (ICAM-1) was conjugated to TAT peptide using a polyethylene glycol (PEG) spacer. PEGylation reduced the transfection efficiency of TAT, but TAT complexes targeting ICAM-1 expressing cells regained much of the lost transfection efficiency. Targeted block peptides properly formulated with calcium offer promise for gene delivery to ICAM-1 expressing cells at sites of injury or inflammation.

Fluorinated copolymer nanoparticles for multimodal imaging applications.

Nanomaterials have emerged as valuable tools in biomedical imaging techniques. Here, the synthesis and characterization of a novel fluorinated nanoparticle with potential applications as an MRI contrast agent is reported. Particles were synthesized using a free radical polymerization technique. Secondary ion mass spectrometry analysis showed that the particles' surface contained fluorinated groups and nitrogen-containing groups. Solid-state NMR spectroscopy suggested the presence of two distinct fluorine resonances, which conforms to the structure of the fluorinated monomer. Ongoing studies aim to evaluate the performance of the nanoparticles as MRI contrast agents both in vitro and in vivo.