In vitro evaluation of functional interaction of integrin alphavbeta3 and matrix metalloprotease-2

Multifunctional fluorescent mesoporous carbon nanoprobe for MMP-2-activated cancer cell imaging and targeted photothermal therapy

The integration of cancer imaging with therapy in a simple system is warranted for precise cancer therapy. In this study, carboxyl-functionalized mesoporous carbon nanospheres (MCN) which are efficient photothermal agents and excellent fluorescence quenchers, were used for cancer cell imaging and selective photothermal therapy (PTT) applications. Using MCN, a matrix metalloproteinase-2 (MMP-2)- responsive theranostic nanoprobe was generated by functionalizing an MMP-2-specific fluorescent-labeled PLGVR sequence on the surface of MCN. The nanoprobe not only can be used to detect MMP-2 with a low detection limit of 0.3 pg mL^-1, but also can achieve the sensitive intracellular MMP-2 imaging in living cells, validating the differentiation of cancer cells from healthy cells based on the recovered fluorescence intensity. More importantly, selective cancer PTT was achieved using MMP-2-triggered cancer cell imaging. Our in vitro studies showed that by regulating the power density and irradiation time, the nanoprobe can effectively kill cancer cells via PTT. Our strategy opens new avenues for precision medicine, especially phototherapy.

Ardisia crispa root hexane fraction suppressed angiogenesis in human umbilical vein endothelial cells (HUVECs) and in vivo zebrafish embryo model

Ardisia crispa Thunb. A. DC. (Primulaceae) has been used extensively as folk-lore medicine in South East Asia including China and Japan to treat various inflammatory related diseases. Ardisia crispa root hexane fraction (ACRH) has been thoroughly studied by our group and it has been shown to exhibit anti-inflammatory, anti-hyperalgesic, anti-arthritic, anti-ulcer, chemoprevention and suppression against inflammation-induced angiogenesis in various animal model. Nevertheless, its effect against human endothelial cells in vitro has not been reported yet. Hence, the aim of the study is to investigate the potential antiangiogenic property of ACRH in human umbilical vein endothelial cells (HUVECs) and zebrafish embryo model. ACRH was separated from the crude ethanolic extract of the plant's root in prior to experimental studies. MTT assay revealed that ACRH exerted a concentration-dependent antiproliferative effect on HUVEC with the IC₅₀ of 2.49 ± 0.04 μg/mL. At higher concentration (10 μg/mL), apoptosis was induced without affecting the cell cycle distribution. Angiogenic properties including migration, invasion and differentiation of HUVECs, evaluated via wound healing, trans-well invasion and tube formation assay respectively, were significantly suppressed by ACRH in a concentration-dependent manner. Noteworthily, significant antiangiogenic effects were observed even at the lowest concentration used (0.1 μg/mL). Expression of proMMP-2, vascular endothelial growth factor (VEGF)-C, VEGF-D, Angiopoietin-2, fibroblast growth factor (FGF)-1, FGF-2, Follistatin, and hepatocyte growth factor (HGF) were significantly reduced in various degrees by ACRH. The ISV formation in zebrafish embryo was significantly suppressed by ACRH at the concentration of 5 μg/mL. These findings revealed the potential of ACRH as antiangiogenic agent by suppressing multiple proangiogenic proteins. Thus, it can be further verified via the transcription of these proteins from their respective DNA, in elucidating their exact pathways.

Magnetic Semiconductor Gd-Doping CuS Nanoparticles as Activatable Nanoprobes for Bimodal Imaging and Targeted Photothermal Therapy of Gastric Tumors

Targeted delivery of enzyme-activatable probes into cancer cells to facilitate accurate imaging and on-demand photothermal therapy (PTT) of cancers with high spatiotemporal precision promises to advance cancer diagnosis and therapy. Here, we report a tumor-targeted and matrix metalloprotease-2 (MMP-2)-activatable nanoprobe (T-MAN) formed by covalent modification of Gd-doping CuS micellar nanoparticles with cRGD and an MMP-2-cleavable fluorescent substrate. T-MAN displays a high r₁ relaxivity (∼60.0 mM^-1 s^-1 per Gd³⁺ at 1 T) and a large near-infrared (NIR) fluorescence turn-on ratio (∼185-fold) in response to MMP-2, allowing high-spatial-resolution magnetic resonance imaging (MRI) and low-background fluorescence imaging of gastric tumors as well as lymph node (LN) metastasis in living mice. Moreover, T-MAN has a high photothermal conversion efficiency (PCE, ∼70.1%) under 808 nm laser irradiation, endowing it with the ability to efficiently generate heat to kill tumor cells. We demonstrate that T-MAN can accumulate preferentially in gastric tumors (∼23.4% ID%/g at 12 h) after intravenous injection into mice, creating opportunities for fluorescence/MR bimodal imaging-guided PTT of subcutaneous and metastatic gastric tumors. For the first time, accurate detection and laser irradiation-initiated photothermal ablation of orthotopic gastric tumors in intraoperative mice was also achieved. This study highlights the versatility of using a combination of dual biomarker recognition (i.e., α_vβ₃ and MMP-2) and dual modality imaging (i.e., MRI and NIR fluorescence) to design tumor-targeting and activatable nanoprobes with improved selectivity for cancer theranostics in vivo.

Dual targeting of integrin αvβ3 and matrix metalloproteinase-2 for optical imaging of tumors and chemotherapeutic delivery

Activatable cell-penetrating peptides (ACPP) provide a general strategy for molecular targeting by exploiting the extracellular protease activities associated with disease. Previous work used a matrix metalloproteinase (MMP-2 and 9)-cleavable sequence in the ACPP to target contrast agents for tumor imaging and fluorescence-guided surgery. To improve specificity and sensitivity for MMP-2, an integrin α(v)β(3)-binding domain, cyclic-RGD, was covalently linked to the ACPP. This co-targeting strategy relies on the interaction of MMP-2 with integrin α(v)β(3), which are known to associate via the hemopexin domain of MMP-2. In U87MG glioblastoma cells in culture, dual targeting greatly improved ACPP uptake compared with either MMP or integrin α(v)β(3) targeting alone. In vivo, dual-targeted ACPP treatment resulted in tumor contrast of 7.8 ± 1.6, a 10-fold higher tumor fluorescence compared with the negative control peptide, and increased probe penetration into the core of MDA-MB-231 tumors. This platform also significantly improved efficacy of the chemotherapeutic monomethylauristatin E (MMAE) in both MDA-MB-231 orthotopic human and syngeneic Py230 murine breast tumors. Treatment with cyclic-RGD-PLGC(Me)AG-MMAE-ACPP resulted in complete tumor regression in one quarter of MDA-MB-231 tumor-bearing mice, compared with no survival in the control groups. This rational mechanism for amplified delivery of imaging and potent chemotherapeutic agents avoids the use of antibodies and may be of considerable generality.

In-house preparation of hydrogels for batch affinity purification of glutathione S-transferase tagged recombinant proteins

Background

Many branches of biomedical research find use for pure recombinant proteins for direct application or to study other molecules and pathways. Glutathione affinity purification is commonly used to isolate and purify glutathione S-transferase (GST)-tagged fusion proteins from total cellular proteins in lysates. Although GST affinity materials are commercially available as glutathione immobilized on beaded agarose resins, few simple options for in-house production of those systems exist. Herein, we describe a novel method for the purification of GST-tagged recombinant proteins.

Results

Glutathione was conjugated to low molecular weight poly(ethylene glycol) diacrylate (PEGDA) via thiol-ene “click” chemistry. With our in-house prepared PEGDA:glutathione (PEGDA:GSH) homogenates, we were able to purify a glutathione S-transferase (GST) green fluorescent protein (GFP) fusion protein (GST-GFP) from the soluble fraction of E. coli lysate. Further, microspheres were formed from the PEGDA:GSH hydrogels and improved protein binding to a level comparable to purchased GSH-agarose beads.

Conclusions

GSH containing polymers might find use as in-house methods of protein purification. They exhibited similar ability to purify GST tagged proteins as purchased GSH agarose beads.

Effects of molecular weight and loading on matrix metalloproteinase-2 mediated release from poly(ethylene glycol) diacrylate hydrogels

Herein, we report on continued efforts to understand an implantable poly(ethylene glycol) diacrylate (PEGDA) hydrogel drug delivery system that responds to extracellular enzymes, in particular matrix metalloproteinase-2 (MMP-2) to provide controlled drug delivery. By attaching peptide as pendant groups on the hydrogel backbone, drug release occurs at an accelerated rate in the presence of active protease. We investigated MMP-2 entry and optimized parameters of the drug delivery system. Mesh size for different PEGDA molecular weight macromers was measured with PEGDA 3,400 hydrogels having a mesh size smaller than the dimensions of MMP-2 and PEGDA 10,000 and PEGDA 20,000 hydrogels having mesh sizes larger than MMP-2. Purified MMP-2 increased release of peptide fragment compared to buffer at several loading concentrations. Cell-stimulated release was demonstrated using U-87 MG cells embedded in collagen. GM6001, an MMP inhibitor, diminished release and altered the identity of the released peptide fragment. The increase in ratio of release from PEGDA 10,000 and PEGDA 20,000 hydrogels compared to PEGDA 3,400 hydrogels suggests MMP-2 enters the hydrogel. PEGDA molecular weight of 10,000 and 15 % (w/V) were the optimal conditions for release and handling. The use of protease-triggered drug delivery has great advantage particularly with the control of protease penetration as a parameter for controlling rate of release.

Improving matrix metalloproteinase-2 specific response of a hydrogel system using electrophoresis

Matrix metalloproteinases (MMPs) overexpression plays a critical role in cancer invasion and metastasis. We utilized this key feature of tumor microenvironment to develop a disease-stimuli triggered drug delivery system. Poly(acrylic acid) hydrogels were synthesized by UV polymerization and pendant MMP-2 sensitive peptides (Gly-Pro-Leu-Gly-Val-Arg-Gly-Lys) conjugated throughout using EDC/sulfo-NHS chemistry. There were significantly more peptides released in the presence of MMP-2 compared with the control groups. The released peptide fragments were analyzed by HPLC and MALDI-MS and confirmed to be the expected fragments. In order to avoid nonspecific release of nonconjugated (i.e. unreacted) peptides, a novel method of electrophoretic washing was developed disrupting the strong electrostatic interactions between the peptides and the pendant groups of the hydrogel. After electrophoresis, the nonspecific peptide release in the absence of MMP-2 was minimized. This newly developed purification system significantly improved the control of release to be in response of the magnitude of the stimuli, i.e. MMP. Specifically, peptides were released proportionally to the concentration of MMP-2 present. Now that many of the design parameters have been examined, anticancer drugs will be conjugated to the MMP sensitive peptide linkers with the goal of implantation in a tumor void releasing anticancer reagent in response to elevated level of MMPs.